Add benchmarks for parsing from a FILE* and for many values from a stream

ParseFILE/* parses the nativejson-benchmark files from a FILE*, and ParseStreamValues/* reads 10,000 small values from one std::istringstream with operator>> (NDJSON objects and plain numbers), which measures the per-value cost of stream input. Signed-off-by: Niels Lohmann <mail@nlohmann.me>
Lock a FILE once per parse instead of once per character
2026-10-14 18:27:13 +00:00 · 2026-10-14 17:34:01 +02:00 · 2026-10-14 17:34:00 +02:00 · 2026-10-14 17:26:38 +02:00 · 2026-10-14 17:13:58 +02:00
81 changed files with 3371 additions and 4919 deletions
@@ -28,7 +28,7 @@ jobs:

    steps:
      - name: Harden Runner
-        uses: step-security/harden-runner@351661ca32ac09a36dc5ee2d536e3128f2a3c8ed # v2.22.0
+        uses: step-security/harden-runner@e14015d583714f6e62063499dc959a02595150a1 # v2.21.1
        with:
          egress-policy: audit

@@ -22,7 +22,7 @@ jobs:
    runs-on: ubuntu-latest
    steps:
      - name: Harden Runner
-        uses: step-security/harden-runner@351661ca32ac09a36dc5ee2d536e3128f2a3c8ed # v2.22.0
+        uses: step-security/harden-runner@e14015d583714f6e62063499dc959a02595150a1 # v2.21.1
        with:
          egress-policy: audit

@@ -46,7 +46,7 @@ jobs:

    steps:
      - name: Harden Runner
-        uses: step-security/harden-runner@351661ca32ac09a36dc5ee2d536e3128f2a3c8ed # v2.22.0
+        uses: step-security/harden-runner@e14015d583714f6e62063499dc959a02595150a1 # v2.21.1
        with:
          egress-policy: audit

@@ -20,7 +20,7 @@ jobs:
    timeout-minutes: 30
    steps:
      - name: Harden Runner
-        uses: step-security/harden-runner@351661ca32ac09a36dc5ee2d536e3128f2a3c8ed # v2.22.0
+        uses: step-security/harden-runner@e14015d583714f6e62063499dc959a02595150a1 # v2.21.1
        with:
          egress-policy: audit

@@ -13,7 +13,7 @@ jobs:
    runs-on: ubuntu-22.04
    steps:
    - name: Harden Runner
-      uses: step-security/harden-runner@351661ca32ac09a36dc5ee2d536e3128f2a3c8ed # v2.22.0
+      uses: step-security/harden-runner@e14015d583714f6e62063499dc959a02595150a1 # v2.21.1
      with:
        egress-policy: audit

@@ -27,7 +27,7 @@ jobs:

    steps:
    - name: Harden Runner
-      uses: step-security/harden-runner@351661ca32ac09a36dc5ee2d536e3128f2a3c8ed # v2.22.0
+      uses: step-security/harden-runner@e14015d583714f6e62063499dc959a02595150a1 # v2.21.1
      with:
        egress-policy: audit

@@ -20,7 +20,7 @@ jobs:
      pull-requests: write
    steps:
      - name: Harden Runner
-        uses: step-security/harden-runner@351661ca32ac09a36dc5ee2d536e3128f2a3c8ed # v2.22.0
+        uses: step-security/harden-runner@e14015d583714f6e62063499dc959a02595150a1 # v2.21.1
        with:
          egress-policy: audit

@@ -21,7 +21,7 @@ jobs:
    runs-on: ubuntu-latest
    steps:
      - name: Harden Runner
-        uses: step-security/harden-runner@351661ca32ac09a36dc5ee2d536e3128f2a3c8ed # v2.22.0
+        uses: step-security/harden-runner@e14015d583714f6e62063499dc959a02595150a1 # v2.21.1
        with:
          egress-policy: audit

@@ -31,7 +31,7 @@ jobs:
      security-events: write
    steps:
      - name: Harden Runner
-        uses: step-security/harden-runner@351661ca32ac09a36dc5ee2d536e3128f2a3c8ed # v2.22.0
+        uses: step-security/harden-runner@e14015d583714f6e62063499dc959a02595150a1 # v2.21.1
        with:
          egress-policy: audit

@@ -23,7 +23,7 @@ jobs:

    steps:
      - name: Harden Runner
-        uses: step-security/harden-runner@351661ca32ac09a36dc5ee2d536e3128f2a3c8ed # v2.22.0
+        uses: step-security/harden-runner@e14015d583714f6e62063499dc959a02595150a1 # v2.21.1
        with:
          egress-policy: audit

@@ -37,7 +37,7 @@ jobs:
    runs-on: ubuntu-latest
    steps:
      - name: Harden Runner
-        uses: step-security/harden-runner@351661ca32ac09a36dc5ee2d536e3128f2a3c8ed # v2.22.0
+        uses: step-security/harden-runner@e14015d583714f6e62063499dc959a02595150a1 # v2.21.1
        with:
          egress-policy: audit

@@ -40,7 +40,7 @@ jobs:

    steps:
      - name: Harden Runner
-        uses: step-security/harden-runner@351661ca32ac09a36dc5ee2d536e3128f2a3c8ed # v2.22.0
+        uses: step-security/harden-runner@e14015d583714f6e62063499dc959a02595150a1 # v2.21.1
        with:
          egress-policy: audit

@@ -36,7 +36,7 @@ jobs:
    runs-on: ubuntu-latest
    steps:
      - name: Harden Runner
-        uses: step-security/harden-runner@351661ca32ac09a36dc5ee2d536e3128f2a3c8ed # v2.22.0
+        uses: step-security/harden-runner@e14015d583714f6e62063499dc959a02595150a1 # v2.21.1
        with:
          egress-policy: audit

@@ -16,7 +16,7 @@ jobs:

    steps:
      - name: Harden Runner
-        uses: step-security/harden-runner@351661ca32ac09a36dc5ee2d536e3128f2a3c8ed # v2.22.0
+        uses: step-security/harden-runner@e14015d583714f6e62063499dc959a02595150a1 # v2.21.1
        with:
          egress-policy: audit

@@ -80,7 +80,7 @@ jobs:
    runs-on: ubuntu-latest
    steps:
      - name: Harden Runner
-        uses: step-security/harden-runner@351661ca32ac09a36dc5ee2d536e3128f2a3c8ed # v2.22.0
+        uses: step-security/harden-runner@e14015d583714f6e62063499dc959a02595150a1 # v2.21.1
        with:
          egress-policy: audit

@@ -112,7 +112,7 @@ jobs:
        target: [ci_test_single_header, ci_cppcheck, ci_cpplint, ci_reproducible_tests, ci_non_git_tests, ci_offline_testdata, ci_reuse_compliance, ci_test_valgrind]
    steps:
      - name: Harden Runner
-        uses: step-security/harden-runner@351661ca32ac09a36dc5ee2d536e3128f2a3c8ed # v2.22.0
+        uses: step-security/harden-runner@e14015d583714f6e62063499dc959a02595150a1 # v2.21.1
        with:
          egress-policy: audit

@@ -178,7 +178,7 @@ jobs:
    runs-on: ubuntu-latest
    steps:
      - name: Harden Runner
-        uses: step-security/harden-runner@351661ca32ac09a36dc5ee2d536e3128f2a3c8ed # v2.22.0
+        uses: step-security/harden-runner@e14015d583714f6e62063499dc959a02595150a1 # v2.21.1
        with:
          egress-policy: audit

@@ -433,7 +433,7 @@ jobs:
    runs-on: ubuntu-latest
    steps:
      - name: Harden Runner
-        uses: step-security/harden-runner@351661ca32ac09a36dc5ee2d536e3128f2a3c8ed # v2.22.0
+        uses: step-security/harden-runner@e14015d583714f6e62063499dc959a02595150a1 # v2.21.1
        with:
          egress-policy: audit

@@ -456,7 +456,7 @@ jobs:
        target: [ci_test_examples, ci_test_build_documentation, ci_test_documentation_mermaid]
    steps:
      - name: Harden Runner
-        uses: step-security/harden-runner@351661ca32ac09a36dc5ee2d536e3128f2a3c8ed # v2.22.0
+        uses: step-security/harden-runner@e14015d583714f6e62063499dc959a02595150a1 # v2.21.1
        with:
          egress-policy: audit

@@ -25,7 +25,6 @@ cc_library(
        "include/nlohmann/detail/conversions/from_json.hpp",
        "include/nlohmann/detail/conversions/to_chars.hpp",
        "include/nlohmann/detail/conversions/to_json.hpp",
-        "include/nlohmann/detail/conversions/zmij.hpp",
        "include/nlohmann/detail/exceptions.hpp",
        "include/nlohmann/detail/hash.hpp",
        "include/nlohmann/detail/input/binary_reader.hpp",
@@ -116,7 +116,7 @@ There is also a [**docset**](https://github.com/Kapeli/Dash-User-Contributions/t
 - **Constructors**: [basic_json](https://json.nlohmann.me/api/basic_json/basic_json), [array](https://json.nlohmann.me/api/basic_json/array), [binary](https://json.nlohmann.me/api/basic_json/binary), [object](https://json.nlohmann.me/api/basic_json/object)
 - **Object inspection**: [type](https://json.nlohmann.me/api/basic_json/type), [operator value_t](https://json.nlohmann.me/api/basic_json/operator_value_t), [type_name](https://json.nlohmann.me/api/basic_json/type_name), [is_primitive](https://json.nlohmann.me/api/basic_json/is_primitive), [is_structured](https://json.nlohmann.me/api/basic_json/is_structured), [is_null](https://json.nlohmann.me/api/basic_json/is_null), [is_boolean](https://json.nlohmann.me/api/basic_json/is_boolean), [is_number](https://json.nlohmann.me/api/basic_json/is_number), [is_number_integer](https://json.nlohmann.me/api/basic_json/is_number_integer), [is_number_unsigned](https://json.nlohmann.me/api/basic_json/is_number_unsigned), [is_number_float](https://json.nlohmann.me/api/basic_json/is_number_float), [is_object](https://json.nlohmann.me/api/basic_json/is_object), [is_array](https://json.nlohmann.me/api/basic_json/is_array), [is_string](https://json.nlohmann.me/api/basic_json/is_string), [is_binary](https://json.nlohmann.me/api/basic_json/is_binary), [is_discarded](https://json.nlohmann.me/api/basic_json/is_discarded)
 - **Value access**: [get](https://json.nlohmann.me/api/basic_json/get), [get_to](https://json.nlohmann.me/api/basic_json/get_to), [get_ptr](https://json.nlohmann.me/api/basic_json/get_ptr), [get_ref](https://json.nlohmann.me/api/basic_json/get_ref), [operator ValueType](https://json.nlohmann.me/api/basic_json/operator_ValueType), [get_binary](https://json.nlohmann.me/api/basic_json/get_binary)
- **Element access**: [at](https://json.nlohmann.me/api/basic_json/at), [operator[]](https://json.nlohmann.me/api/basic_json/operator%5B%5D/), [value](https://json.nlohmann.me/api/basic_json/value), [front](https://json.nlohmann.me/api/basic_json/front), [back](https://json.nlohmann.me/api/basic_json/back)
+- **Element access**: [at](https://json.nlohmann.me/api/basic_json/at), [operator[]](https://json.nlohmann.me/api/basic_json/operator[]), [value](https://json.nlohmann.me/api/basic_json/value), [front](https://json.nlohmann.me/api/basic_json/front), [back](https://json.nlohmann.me/api/basic_json/back)
 - **Lookup**: [find](https://json.nlohmann.me/api/basic_json/find), [count](https://json.nlohmann.me/api/basic_json/count), [contains](https://json.nlohmann.me/api/basic_json/contains)
 - **Iterators**: [begin](https://json.nlohmann.me/api/basic_json/begin), [cbegin](https://json.nlohmann.me/api/basic_json/cbegin), [end](https://json.nlohmann.me/api/basic_json/end), [cend](https://json.nlohmann.me/api/basic_json/cend), [rbegin](https://json.nlohmann.me/api/basic_json/rbegin), [rend](https://json.nlohmann.me/api/basic_json/rend), [crbegin](https://json.nlohmann.me/api/basic_json/crbegin), [crend](https://json.nlohmann.me/api/basic_json/crend), [items](https://json.nlohmann.me/api/basic_json/items)
 - **Capacity**: [empty](https://json.nlohmann.me/api/basic_json/empty), [size](https://json.nlohmann.me/api/basic_json/size), [max_size](https://json.nlohmann.me/api/basic_json/max_size)
@@ -125,7 +125,7 @@ There is also a [**docset**](https://github.com/Kapeli/Dash-User-Contributions/t
 - **Serialization / Dumping**: [dump](https://json.nlohmann.me/api/basic_json/dump)
 - **Deserialization / Parsing**: [parse](https://json.nlohmann.me/api/basic_json/parse), [accept](https://json.nlohmann.me/api/basic_json/accept), [sax_parse](https://json.nlohmann.me/api/basic_json/sax_parse)
 - **JSON Pointer functions**: [flatten](https://json.nlohmann.me/api/basic_json/flatten), [unflatten](https://json.nlohmann.me/api/basic_json/unflatten)
- **JSON Patch functions**: [patch](https://json.nlohmann.me/api/basic_json/patch), [patch_inplace](https://json.nlohmann.me/api/basic_json/patch_inplace), [diff](https://json.nlohmann.me/api/basic_json/diff), [merge_patch](https://json.nlohmann.me/api/basic_json/merge_patch), [merge_diff](https://json.nlohmann.me/api/basic_json/merge_diff)
+- **JSON Patch functions**: [patch](https://json.nlohmann.me/api/basic_json/patch), [patch_inplace](https://json.nlohmann.me/api/basic_json/patch_inplace), [diff](https://json.nlohmann.me/api/basic_json/diff), [merge_patch](https://json.nlohmann.me/api/basic_json/merge_patch)
 - **Static functions**: [meta](https://json.nlohmann.me/api/basic_json/meta), [get_allocator](https://json.nlohmann.me/api/basic_json/get_allocator)
 - **Binary formats**: [from_bjdata](https://json.nlohmann.me/api/basic_json/from_bjdata), [from_bon8](https://json.nlohmann.me/api/basic_json/from_bon8), [from_bson](https://json.nlohmann.me/api/basic_json/from_bson), [from_cbor](https://json.nlohmann.me/api/basic_json/from_cbor), [from_msgpack](https://json.nlohmann.me/api/basic_json/from_msgpack), [from_ubjson](https://json.nlohmann.me/api/basic_json/from_ubjson), [to_bjdata](https://json.nlohmann.me/api/basic_json/to_bjdata), [to_bon8](https://json.nlohmann.me/api/basic_json/to_bon8), [to_bson](https://json.nlohmann.me/api/basic_json/to_bson), [to_cbor](https://json.nlohmann.me/api/basic_json/to_cbor), [to_msgpack](https://json.nlohmann.me/api/basic_json/to_msgpack), [to_ubjson](https://json.nlohmann.me/api/basic_json/to_ubjson)
 - **Non-member functions**: [operator<<](https://json.nlohmann.me/api/operator_ltlt/), [operator>>](https://json.nlohmann.me/api/operator_gtgt/), [to_string](https://json.nlohmann.me/api/basic_json/to_string)
@@ -360,7 +360,7 @@ std::cout << cpp_string << " == " << cpp_string2 << " == " << j_string.get<std::
 std::cout << j_string << " == " << serialized_string << std::endl;
 ```

-[`.dump()`](https://json.nlohmann.me/api/basic_json/dump/) returns the serialized JSON text, so a string value is enclosed in quotes and special characters are escaped. Use [`get<std::string>()`](https://json.nlohmann.me/api/basic_json/get/) to retrieve the originally stored string value.
+[`.dump()`](https://json.nlohmann.me/api/basic_json/dump/) returns the originally stored string value.

 Note the library only supports UTF-8. When you store strings with different encodings in the library, calling [`dump()`](https://json.nlohmann.me/api/basic_json/dump/) may throw an exception unless `json::error_handler_t::replace`, `json::error_handler_t::ignore`, or `json::error_handler_t::keep` are used as error handlers.

@@ -687,15 +687,15 @@ json j_result = j_original.patch(j_patch);
 // calculate a JSON patch from two JSON values
 json::diff(j_result, j_original);
 // [
-//   { "op": "replace", "path": "/baz", "value": ["one", "two", "three"] },
-//   { "op": "remove", "path": "/hello" },
+//   { "op":" replace", "path": "/baz", "value": ["one", "two", "three"] },
+//   { "op": "remove","path": "/hello" },
 //   { "op": "add", "path": "/foo", "value": "bar" }
 // ]
 ```

 ### JSON Merge Patch

-The library supports **JSON Merge Patch** ([RFC 7396](https://tools.ietf.org/html/rfc7396)) as a patch format. Instead of using JSON Pointer (see above) to specify values to be manipulated, it describes the changes using a syntax that closely mimics the document being modified.
+The library supports **JSON Merge Patch** ([RFC 7386](https://tools.ietf.org/html/rfc7386)) as a patch format. Instead of using JSON Pointer (see above) to specify values to be manipulated, it describes the changes using a syntax that closely mimics the document being modified.

 ```cpp
 // a JSON value
@@ -725,20 +725,6 @@ j_document.merge_patch(j_patch);
 // }
 ```

-Conversely, [`merge_diff`](https://json.nlohmann.me/api/basic_json/merge_diff/) creates a merge patch from two JSON values:
-
-```cpp
-// create a merge patch that turns j_original into j_document
-json j_original = R"({"a": "b", "c": {"d": "e", "f": "g"}})"_json;
-json::merge_diff(j_original, j_document);
-// {
-//  "a": "z",
-//  "c": {
-//    "f": null
-//  }
-// }
-```
-
 ### Implicit conversions

 Supported types can be implicitly converted to JSON values.
@@ -1280,9 +1266,13 @@ The package configuration file, `nlohmann_jsonConfig.cmake`, can be used either
 To embed the library directly into an existing CMake project, place the entire source tree in a subdirectory and call `add_subdirectory()` in your `CMakeLists.txt` file:

 ```cmake
+# Typically you don't care so much for a third party library's tests to be
+# run from your own project's code.
+set(JSON_BuildTests OFF CACHE INTERNAL "")
+
 # If you only include this third party in PRIVATE source files, you do not
 # need to install it when your main project gets installed.
-set(JSON_Install OFF CACHE INTERNAL "")
+# set(JSON_Install OFF CACHE INTERNAL "")

 # Don't use include(nlohmann_json/CMakeLists.txt) since that carries with it
 # unintended consequences that will break the build.  It's generally
@@ -1297,8 +1287,8 @@ target_link_libraries(foo PRIVATE nlohmann_json::nlohmann_json)

 ##### Embedded (FetchContent)

-Since CMake v3.14,
-[FetchContent](https://cmake.org/cmake/help/v3.14/module/FetchContent.html) can
+Since CMake v3.11,
+[FetchContent](https://cmake.org/cmake/help/v3.11/module/FetchContent.html) can
 be used to automatically download a release as a dependency at configure time.

 Example:
@@ -1363,9 +1353,7 @@ Use your favorite [**package manager**](https://json.nlohmann.me/integration/pac
 - <img src="https://raw.githubusercontent.com/nlohmann/json/refs/heads/develop/docs/mkdocs/docs/images/package_managers/swift.svg" height="20">&nbsp;[**Swift Package Manager**](https://json.nlohmann.me/integration/package_managers/#swift-package-manager) `nlohmann/json`
 - <img src="https://raw.githubusercontent.com/nlohmann/json/refs/heads/develop/docs/mkdocs/docs/images/package_managers/nuget.svg" height="20">&nbsp;[**Nuget**](https://json.nlohmann.me/integration/package_managers/#nuget) `nlohmann.json`
 - <img src="https://raw.githubusercontent.com/nlohmann/json/refs/heads/develop/docs/mkdocs/docs/images/package_managers/conda.svg" height="20">&nbsp;[**Conda**](https://json.nlohmann.me/integration/package_managers/#conda) `nlohmann_json`
- [**MSYS2**](https://json.nlohmann.me/integration/package_managers/#msys2) `mingw-w64-nlohmann-json`
 - <img src="https://raw.githubusercontent.com/nlohmann/json/refs/heads/develop/docs/mkdocs/docs/images/package_managers/macports.svg" height="20">&nbsp;[**MacPorts**](https://json.nlohmann.me/integration/package_managers/#macports) `nlohmann-json`
- [**build2**](https://json.nlohmann.me/integration/package_managers/#build2) `nlohmann-json`
 - <img src="https://raw.githubusercontent.com/nlohmann/json/refs/heads/develop/docs/mkdocs/docs/images/package_managers/CPM.png" height="20">&nbsp;[**cpm.cmake**](https://json.nlohmann.me/integration/package_managers/#cpmcmake) `gh:nlohmann/json`
 - <img src="https://raw.githubusercontent.com/nlohmann/json/refs/heads/develop/docs/mkdocs/docs/images/package_managers/xmake.svg" height="20">&nbsp;[**xmake**](https://json.nlohmann.me/integration/package_managers/#xmake) `nlohmann_json`

@@ -1397,10 +1385,9 @@ THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR I

 - The class contains the UTF-8 Decoder from Bjoern Hoehrmann which is licensed under the [MIT License](https://opensource.org/licenses/MIT) (see above). Copyright &copy; 2008-2009 [Björn Hoehrmann](https://bjoern.hoehrmann.de/) <bjoern@hoehrmann.de>
 - The class contains a slightly modified version of the Grisu2 algorithm from Florian Loitsch which is licensed under the [MIT License](https://opensource.org/licenses/MIT) (see above). Copyright &copy; 2009 [Florian Loitsch](https://florian.loitsch.com/)
- The class contains a port of the shortest double-to-decimal conversion of [Żmij](https://github.com/vitaut/zmij) by Victor Zverovich, including the conversion of the digits to text by Xiang JunBo and the SIMD instruction sequence of Dougall Johnson, which is licensed under the [MIT License](https://opensource.org/licenses/MIT) (see above). Copyright &copy; 2025 [Victor Zverovich](https://github.com/vitaut)
 - The class contains a copy of [Hedley](https://nemequ.github.io/hedley/) from Evan Nemerson which is licensed as [CC0-1.0](https://creativecommons.org/publicdomain/zero/1.0/).
 - The class contains parts of [Google Abseil](https://github.com/abseil/abseil-cpp) which is licensed under the [Apache 2.0 License](https://opensource.org/licenses/Apache-2.0).
- The class contains an adapted version of the Eisel-Lemire algorithm, its table of powers of five, and its digit comparison for long numbers from [fast_float](https://github.com/fastfloat/fast_float) by Daniel Lemire and contributors, which is available under the [MIT License](https://opensource.org/licenses/MIT) (used here), the Apache 2.0 License, and the Boost Software License. Copyright &copy; 2021 The fast_float authors
+- The class contains an adapted version of the Eisel-Lemire algorithm and its table of powers of five from [fast_float](https://github.com/fastfloat/fast_float) by Daniel Lemire and contributors, which is available under the [MIT License](https://opensource.org/licenses/MIT) (used here), the Apache 2.0 License, and the Boost Software License. Copyright &copy; 2021 The fast_float authors

 <img align="right" src="https://git.fsfe.org/reuse/reuse-ci/raw/branch/master/reuse-horizontal.png" alt="REUSE Software">

@@ -485,13 +485,6 @@ add_custom_target(ci_clang_analyze
 # Check code with Cppcheck.
 ###############################################################################

-# default_defines.hpp expands the Hedley macros to the compiler's feature-test operators, which Cppcheck does not know.
-# Since Cppcheck 2.20, it rejects their invocations in #if conditions instead of evaluating them as 0.
-file(WRITE ${CMAKE_BINARY_DIR}/cppcheck_feature_tests.hpp "")
-foreach(OPERATOR __has_attribute __has_builtin __has_cpp_attribute __has_declspec_attribute __has_extension __has_feature __has_include __has_warning)
-    file(APPEND ${CMAKE_BINARY_DIR}/cppcheck_feature_tests.hpp "#define ${OPERATOR}(x) 0\n")
-endforeach()
-
 add_custom_target(ci_cppcheck
    COMMAND mkdir -p cppcheck
    COMMAND clang -dM -E -x c++ -std=c++11 ${CMAKE_SOURCE_DIR}/include/nlohmann/thirdparty/hedley/hedley.hpp > default_defines.hpp 2> /dev/null
@@ -500,7 +493,7 @@ add_custom_target(ci_cppcheck
    COMMAND venv_cppcheck/bin/cppcheck --enable=warning --check-level=exhaustive --inline-suppr --inconclusive --force
            --std=c++11 ${PROJECT_SOURCE_DIR}/include/nlohmann/json.hpp -I ${CMAKE_SOURCE_DIR}/include
            --error-exitcode=1 --relative-paths=${PROJECT_SOURCE_DIR} -j ${N} --include=default_defines.hpp
-            --include=${CMAKE_BINARY_DIR}/cppcheck_feature_tests.hpp --cppcheck-build-dir=cppcheck
+            --cppcheck-build-dir=cppcheck
            -UJSON_CATCH_USER -UJSON_TRY_USER -UJSON_ASSERT -UJSON_INTERNAL_CATCH -UJSON_THROW
            -DJSON_HAS_CPP_11 -UJSON_HAS_CPP_14 -UJSON_HAS_CPP_17 -UJSON_HAS_CPP_20 -UJSON_HAS_THREE_WAY_COMPARISON
    COMMENT "Check code with Cppcheck"
@@ -1 +1 @@
-cppcheck==1.5.2
+cppcheck==1.5.1
@@ -132,6 +132,10 @@ outside of a string, invalid) byte; see the [FAQ entry](../../home/faq.md#nul-by
 - [operator>>](../operator_gtgt.md) - deserialize from stream
 - [`JSON_STRICT_NUL_HANDLING`](../macros/json_strict_nul_handling.md) - opt in to rejecting a NUL byte in the input
  instead of treating it as end of input
+- [`JSON_DISABLE_STREAM_BULK_SCAN`](../macros/json_disable_stream_bulk_scan.md) - read a `std::istream` one character
+  at a time
+- [`JSON_DISABLE_UNLOCKED_FILE_IO`](../macros/json_disable_unlocked_file_io.md) - read a `FILE*` with the locking stdio
+  functions

 ## Version history

@@ -143,6 +147,10 @@ outside of a string, invalid) byte; see the [FAQ entry](../../home/faq.md#nul-by
 - Extended overload (2) to accept heterogeneous iterator+sentinel pairs (C++20 ranges support) in version 3.13.0.
 - `JSON_STRICT_NUL_HANDLING` added in version 3.13.0 to optionally reject a NUL byte in the input instead of treating
  it as end of input; planned to become the default in version 4.0.0.
+- Parsing from an `std::istream` scans the characters in its stream buffer in bulk in version 3.13.0
+  ([`JSON_DISABLE_STREAM_BULK_SCAN`](../macros/json_disable_stream_bulk_scan.md)).
+- Parsing from a `FILE*` locks the file once instead of once per character in version 3.13.0
+  ([`JSON_DISABLE_UNLOCKED_FILE_IO`](../macros/json_disable_unlocked_file_io.md)).

 !!! warning "Deprecation"

@@ -62,9 +62,6 @@ Linear.

 ## Notes

-Floating-point numbers are written with the fewest digits that read back as the same value (for `#!cpp double`; see
-[number handling](../../features/types/number_handling.md#number-serialization)).
-
 Binary values are serialized as an object containing two keys:

 - "bytes": an array of bytes as integers
@@ -100,5 +97,3 @@ Binary values are serialized as an object containing two keys:
 - Error handlers added in version 3.4.0.
 - Serialization of binary values added in version 3.8.0.
 - Error handler `keep` added in version 3.13.0.
- Doubles are written with the shortest digits (Żmij instead of Grisu2) since version 3.13.0; about 0.1% of doubles are
-  written differently, most of them with fewer digits.
@@ -85,7 +85,7 @@ The class satisfies the following concept requirements:
 - [EqualityComparable](https://en.cppreference.com/w/cpp/named_req/EqualityComparable): JSON values can be compared with
  `==`, see [`operator==`](operator_eq.md).
 - [LessThanComparable](https://en.cppreference.com/w/cpp/named_req/LessThanComparable): JSON values can be compared with
-  `<`, see [`operator<`](operator_lt.md).
+  `<`, see [`operator<`](operator_le.md).
 - [Swappable](https://en.cppreference.com/w/cpp/named_req/Swappable): Any JSON lvalue or rvalue of can be swapped with
  any lvalue or rvalue of other compatible types, using unqualified function `swap`.
 - [NullablePointer](https://en.cppreference.com/w/cpp/named_req/NullablePointer): JSON values can be compared against
@@ -11,7 +11,7 @@ added members with their new values, and removed members with the value `#!json
 member by member; any other value that differs, including an array, is replaced as a whole.

 For two JSON values `source` and `target`, where `target` contains no object member whose value is `#!json null`, the
-following code always yields `#!cpp true` (for [`ordered_json`](../ordered_json.md), see the notes below):
+following code always yields `#!cpp true`:
 ```cpp
 basic_json patched = source;
 patched.merge_patch(merge_diff(source, target));
@@ -23,10 +23,9 @@ type to use.
 ## Template parameters

 `NumberFloatType`
-:   the type to store floating-point numbers. The type must be `#!cpp float`, `#!cpp double`, or
-    `#!cpp long double`. The parser converts `#!cpp float`, `#!cpp double`, and a `#!cpp long double` that is IEEE 754
-    binary64 itself. It converts other `#!cpp long double` formats with `#!cpp std::from_chars` where available, or
-    with `#!cpp std::strtold` otherwise. Serialization falls back to `#!cpp std::snprintf`. The
+:   the type to store floating-point numbers. Parsing and serialization are implemented in terms of
+    `#!cpp std::strtof`/`#!cpp std::strtod`/`#!cpp std::strtold` and `#!cpp std::snprintf`, so the type must be
+    `#!cpp float`, `#!cpp double`, or `#!cpp long double`. The
    [binary formats](../../features/binary_formats/index.md) additionally require `#!cpp float` or `#!cpp double`,
    because they have no encoding for `#!cpp long double`. See
    [Template Parameter Requirements](../../features/types/template_parameters.md#numberfloattype).
@@ -52,10 +51,9 @@ With the default values for `NumberFloatType` (`double`), the default value for
 > interoperability can be achieved by implementations that expect no more precision or range than these provide, in the
 > sense that implementations will approximate JSON numbers within the expected precision.

-This implementation does exactly follow this approach, as it uses double precision floating-point numbers. Note that
-numbers smaller than `-1.79769313486232e+308` or greater than `1.79769313486232e+308` are rejected during parsing with
-[`out_of_range.406`](../../home/exceptions.md#jsonexceptionout_of_range406). Non-finite values (NaN and infinity) can
-only be stored by assigning them directly and are serialized to `null`.
+This implementation does exactly follow this approach, as it uses double precision floating-point numbers. Note values
+smaller than `-1.79769313486232e+308` and values greater than `1.79769313486232e+308` will be stored as NaN internally
+and be serialized to `null`.

 During deserialization (from JSON text or any of the binary formats), a finite number that does not fit into
 `number_float_t` is rejected with [`out_of_range.406`](../../home/exceptions.md#jsonexceptionout_of_range406), for
@@ -20,8 +20,7 @@ bool operator==(ScalarType rhs) const noexcept(/* see below */); // (2)
 1. Compares two JSON values for equality according to the following rules:
    - Two JSON values are equal if (1) neither value is discarded, and (2) they are of the same type and their stored
      values are the same according to their respective `operator==`.
-    - Integer and floating-point numbers are compared by their exact values, without converting the integer to
-      floating-point. For instance, `9007199254740993` and `9007199254740992.0` are not equal.
+    - Integer and floating-point numbers are automatically converted before comparison.

 2. Compares a JSON value and a scalar or a scalar and a JSON value for equality by converting the
   scalar to a JSON value and comparing both JSON values according to 1.
@@ -15,8 +15,7 @@ bool operator<(ScalarType lhs, const const_reference rhs) noexcept(/* see below
  following rules:
    - If either operand is discarded, the comparison yields `#!cpp false`.
    - If both operands have the same type, the values are compared using their respective `operator<`.
-    - Integer and floating-point numbers are compared by their exact values, without converting the integer to
-      floating-point. For instance, `9007199254740992.0` is less than `9007199254740993`.
+    - Integer and floating-point numbers are automatically converted before comparison.
    - In case `lhs` and `rhs` have different types, the values are ignored and the order of the types
      is considered, which is:
        1. null
@@ -12,8 +12,10 @@ std::partial_ordering operator<=>(const ScalarType rhs) const noexcept(/* see be
    - Two JSON values compare with a result of `std::partial_ordering::unordered` if either value is discarded.
    - If both JSON values are of the same type, the result is produced by 3-way comparing their stored values using
      their respective `operator<=>`.
-    - Integer and floating-point numbers are 3-way compared by their exact values, without converting the integer to
-      floating-point. For instance, `9007199254740993` compares greater than `9007199254740992.0`.
+    - Integer and floating-point numbers are converted to their common type and then 3-way compared using their
+      respective `operator<=>`.
+      For instance, comparing an integer and a floating-point value will 3-way compare the first value converted to
+      floating-point with the second value.
    - Otherwise, yields a result by comparing the type (see [`value_t`](value_t.md)).
  
 2. 3-way compares a JSON value and a scalar or a scalar and a JSON value by converting the scalar to a JSON value and
@@ -112,6 +112,16 @@ By default, a `'\0'` (NUL) byte anywhere in the input is treated as end of input
 outside of a string, invalid) byte; see the [FAQ entry](../../home/faq.md#nul-bytes-in-the-input) for details and the
 [`JSON_STRICT_NUL_HANDLING`](../macros/json_strict_nul_handling.md) macro to opt into rejecting it instead.

+!!! tip "Performance"
+
+    Contiguous inputs (strings, string views, vectors, arrays, pointer ranges) are the fastest to parse. A
+    `#!cpp std::istream` comes close: the parser scans the characters its stream buffer holds in bulk, without reading
+    ahead, so the stream is left exactly where it would be after reading one character at a time. A `#!cpp FILE*` is
+    read one character at a time, but the file is locked only once, so other threads that use the same `FILE` object
+    wait until parsing is done. See [input sources and performance](../../features/parsing/index.md#input-sources-and-performance),
+    [`JSON_DISABLE_STREAM_BULK_SCAN`](../macros/json_disable_stream_bulk_scan.md), and
+    [`JSON_DISABLE_UNLOCKED_FILE_IO`](../macros/json_disable_unlocked_file_io.md).
+
 ## Examples

 ??? example "Example: (1) parse from a character array"
@@ -247,6 +257,10 @@ outside of a string, invalid) byte; see the [FAQ entry](../../home/faq.md#nul-by
 - [operator>>](../operator_gtgt.md) - deserialize from stream
 - [`JSON_STRICT_NUL_HANDLING`](../macros/json_strict_nul_handling.md) - opt in to rejecting a NUL byte in the input
  instead of treating it as end of input
+- [`JSON_DISABLE_STREAM_BULK_SCAN`](../macros/json_disable_stream_bulk_scan.md) - read a `std::istream` one character
+  at a time
+- [`JSON_DISABLE_UNLOCKED_FILE_IO`](../macros/json_disable_unlocked_file_io.md) - read a `FILE*` with the locking stdio
+  functions

 ## Version history

@@ -261,6 +275,11 @@ outside of a string, invalid) byte; see the [FAQ entry](../../home/faq.md#nul-by
  it as end of input; planned to become the default in version 4.0.0.
 - Extended empty-input detection to also cover an `std::istream` without a stream buffer, and fixed a crash
  (`std::terminate`) when parsing from an `std::istream` with `eofbit` in its exception mask, in version 3.13.0.
+- Parsing from an `std::istream` scans the characters in its stream buffer in bulk in version 3.13.0
+  ([`JSON_DISABLE_STREAM_BULK_SCAN`](../macros/json_disable_stream_bulk_scan.md) restores reading one character at a
+  time).
+- Parsing from a `FILE*` locks the file once instead of once per character in version 3.13.0
+  ([`JSON_DISABLE_UNLOCKED_FILE_IO`](../macros/json_disable_unlocked_file_io.md) restores `std::fgetc`).

 !!! warning "Deprecation"

@@ -45,7 +45,7 @@ Strong guarantee: if an exception is thrown, there are no changes in the JSON va
  pointer inside the patch cannot be resolved, e.g., `-` in a "remove" operation or `1a` for an array; example:
  `"unresolved reference token '-'"`.
 - Throws [`out_of_range.405`](../../home/exceptions.md#jsonexceptionout_of_range405) if JSON pointer has no parent
-  ("remove", "move")
+  ("add", "remove", "move")
 - Throws [`out_of_range.411`](../../home/exceptions.md#jsonexceptionout_of_range411) if an "add" operation's target
  location has a parent that is neither an object nor an array.
 - Throws [`out_of_range.413`](../../home/exceptions.md#jsonexceptionout_of_range413) if a "remove" operation's target
@@ -41,7 +41,7 @@ No guarantees, value may be corrupted by an unsuccessful patch operation.
  pointer inside the patch cannot be resolved, e.g., `-` in a "remove" operation or `1a` for an array; example:
  `"unresolved reference token '-'"`.
 - Throws [`out_of_range.405`](../../home/exceptions.md#jsonexceptionout_of_range405) if JSON pointer has no parent
-  ("remove", "move")
+  ("add", "remove", "move")
 - Throws [`out_of_range.411`](../../home/exceptions.md#jsonexceptionout_of_range411) if an "add" operation's target
  location has a parent that is neither an object nor an array.
 - Throws [`out_of_range.413`](../../home/exceptions.md#jsonexceptionout_of_range413) if a "remove" operation's target
@@ -116,6 +116,10 @@ consumer `sax` has a super-linear complexity.

 A UTF-8 byte order mark is silently ignored.

+When reading from a `#!c FILE*`, the file is locked while it is parsed. The lock is recursive, so the SAX handler may
+use the same file with stdio functions, but it must not wait for another thread that uses the same `FILE` object; see
+[`JSON_DISABLE_UNLOCKED_FILE_IO`](../macros/json_disable_unlocked_file_io.md).
+
 ## Examples

 ??? example
@@ -137,6 +141,10 @@ A UTF-8 byte order mark is silently ignored.

 - [parse](parse.md) - deserialize from a compatible input
 - [accept](accept.md) - check if the input is valid JSON
+- [`JSON_DISABLE_STREAM_BULK_SCAN`](../macros/json_disable_stream_bulk_scan.md) - read a `std::istream` one character
+  at a time
+- [`JSON_DISABLE_UNLOCKED_FILE_IO`](../macros/json_disable_unlocked_file_io.md) - read a `FILE*` with the locking stdio
+  functions

 ## Version history

@@ -148,6 +156,10 @@ A UTF-8 byte order mark is silently ignored.
 - Extended overload (2) to accept heterogeneous iterator+sentinel pairs (C++20 ranges support) in version 3.13.0.
 - `JSON_PRECISE_STREAM_POSITION` added in version 3.13.0 to optionally leave a `#!cpp std::istream` positioned right
  after the parsed value when `strict` is `#!cpp false`.
+- Parsing from an `std::istream` scans the characters in its stream buffer in bulk in version 3.13.0
+  ([`JSON_DISABLE_STREAM_BULK_SCAN`](../macros/json_disable_stream_bulk_scan.md)).
+- Parsing from a `FILE*` locks the file once instead of once per character in version 3.13.0
+  ([`JSON_DISABLE_UNLOCKED_FILE_IO`](../macros/json_disable_unlocked_file_io.md)).

 !!! warning "Deprecation"

@@ -16,6 +16,10 @@ header. See also the [macro overview page](../../features/macros.md).

 ## Parsing

+- [**JSON_DISABLE_STREAM_BULK_SCAN**](json_disable_stream_bulk_scan.md) - read a `std::istream` one character at a time
+  instead of scanning its stream buffer in bulk
+- [**JSON_DISABLE_UNLOCKED_FILE_IO**](json_disable_unlocked_file_io.md) - read a `FILE*` with `std::fgetc` instead of
+  locking it once and using the unlocked stdio functions
 - [**JSON_PRECISE_STREAM_POSITION**](json_precise_stream_position.md) - opt in to leaving an input stream positioned
  right after a parsed number
 - [**JSON_STRICT_BINARY_UTF8**](json_strict_binary_utf8.md) - opt in to checking strings for valid UTF-8 in the CBOR,
@@ -0,0 +1,145 @@
+# JSON_DISABLE_STREAM_BULK_SCAN
+
+```cpp
+#define JSON_DISABLE_STREAM_BULK_SCAN /* value */
+```
+
+When defined to `1`, parsing from a `#!cpp std::istream` reads the input one character at a time through the stream
+buffer, as in version 3.12.0 and earlier, instead of scanning the characters that the stream buffer already holds in
+bulk.
+
+The macro is an escape hatch for stream buffers that do not follow the usual contract of `std::basic_streambuf` (see
+the requirements on the stream buffer in the notes below). It does not change any result: values, exceptions, and the
+position of the stream after parsing are the same either way. Only the speed differs.
+
+## Default definition
+
+The default value is `0`: streams are scanned in bulk.
+
+```cpp
+#define JSON_DISABLE_STREAM_BULK_SCAN 0
+```
+
+## Notes
+
+!!! note "How streams are scanned"
+
+    A `std::streambuf` keeps the part of the input it has read but not yet handed out in its *get area*, the range
+    from `gptr()` to `egptr()`. A `std::filebuf`, for instance, reads the file in blocks of a few kilobytes into its get
+    area, and a `std::stringbuf` exposes its whole string as one get area.
+
+    When parsing from a `std::istream`, the parser scans this get area directly, with the same fast paths that it uses
+    for a `std::string`: runs of ordinary string characters, numbers, and indentation are recognized several bytes at a
+    time instead of being requested from the stream buffer one character at a time. When the parser reaches the end of
+    the get area, it asks the stream buffer for the next character as before, which makes the stream buffer refill its
+    get area.
+
+    The parser only reads characters that it would also have read one at a time, and it advances the stream buffer
+    exactly over the characters it consumes. Nothing is read ahead, buffered elsewhere, or put back. Therefore, the
+    stream is left exactly where it was left before:
+
+    - [`operator>>`](../operator_gtgt.md) and [`sax_parse`](../basic_json/sax_parse.md) with `strict = false` can still
+      read several values from one stream, and the stream can still be used with other `std::istream` functions after a
+      value has been read.
+    - With [`JSON_PRECISE_STREAM_POSITION`](json_precise_stream_position.md), the stream is still positioned right after
+      a parsed number.
+    - Exception messages, including the line, the column, and the last read token, are unchanged.
+
+!!! note "Performance"
+
+    Parsing from a `std::ifstream` or `std::istringstream` is typically 1.5 to 2 times as fast as before, and reading
+    many small values from one stream with `operator>>` 1.4 to 4 times as fast. Parsing from a stream is then within
+    about 10 to 20 % of first reading the whole file into a `std::string` and parsing that.
+
+    A stream buffer without a get area (one that only overrides `underflow()` and `uflow()` and hands out every
+    character from there) offers nothing to scan in bulk, so it is read one character at a time as before.
+
+!!! note "Requirements on the stream buffer"
+
+    The bulk scan relies on the following behavior, which every stream buffer of the standard library and every stream
+    buffer that keeps its input in its get area has:
+
+    - When `sgetc()` returns a character while `gptr() < egptr()`, that character is `*gptr()`; when `sbumpc()` returns
+      one, it was at `gptr()` before the call.
+    - Characters in the get area are not changed while they are in the get area.
+    - `underflow()` or `uflow()` either sets up a get area that holds the returned character at `gptr()` (or at
+      `gptr() - 1` after `uflow()`), or leaves the get area empty.
+
+    A stream buffer that returns characters from `uflow()` while leaving unrelated characters in its get area, or that
+    changes the characters in its get area in place, does not meet these requirements. Define the macro to `1` for
+    such stream buffers.
+
+!!! warning "Define consistently"
+
+    The macro selects between two definitions of the library's internal stream input adapter. It must therefore be
+    defined identically for **every** translation unit that includes the library; mixing translation units that define
+    it with ones that do not is an ODR violation. Prefer setting it as a compile definition on the target rather than
+    with `#!cpp #define` in individual source files.
+
+!!! note "Other inputs"
+
+    Strings, string views, vectors, arrays, and pointer or iterator ranges over contiguous memory are scanned in bulk
+    anyway. Reading from a `#!cpp FILE*` is not affected by this macro; see
+    [`JSON_DISABLE_UNLOCKED_FILE_IO`](json_disable_unlocked_file_io.md) for that input.
+
+## Examples
+
+??? example "Example: reading values from a stream (default)"
+
+    The stream is scanned in bulk, and the values are read one after the other:
+
+    ```cpp
+    #include <iostream>
+    #include <sstream>
+    #include <nlohmann/json.hpp>
+
+    using json = nlohmann::json;
+
+    int main()
+    {
+        std::istringstream input(R"({"id": 1} {"id": 2} 42 rest)");
+        json j1, j2, j3;
+        input >> j1 >> j2 >> j3;  // {"id":1}, {"id":2}, 42
+
+        std::string word;
+        input >> word;            // "rest"
+    }
+    ```
+
+??? example "Example: reading one character at a time (macro defined to 1)"
+
+    With the macro, the same program reads the stream one character at a time, with the same results:
+
+    ```cpp
+    #define JSON_DISABLE_STREAM_BULK_SCAN 1
+    #include <iostream>
+    #include <sstream>
+    #include <nlohmann/json.hpp>
+
+    using json = nlohmann::json;
+
+    int main()
+    {
+        std::istringstream input(R"({"id": 1} {"id": 2} 42 rest)");
+        json j1, j2, j3;
+        input >> j1 >> j2 >> j3;  // {"id":1}, {"id":2}, 42
+
+        std::string word;
+        input >> word;            // "rest"
+    }
+    ```
+
+## See also
+
+- [**parse**](../basic_json/parse.md) - deserialize from a compatible input
+- [**operator>>**](../operator_gtgt.md) - deserialize from stream
+- [**sax_parse**](../basic_json/sax_parse.md) - generate SAX events
+- [**JSON_PRECISE_STREAM_POSITION**](json_precise_stream_position.md) - leave an input stream positioned right after a
+  parsed number
+- [**JSON_DISABLE_UNLOCKED_FILE_IO**](json_disable_unlocked_file_io.md) - read a `FILE*` with the locking stdio
+  functions
+- [Parsing: input sources and performance](../../features/parsing/index.md#input-sources-and-performance)
+
+## Version history
+
+- Added in version 3.13.0.
@@ -0,0 +1,113 @@
+# JSON_DISABLE_UNLOCKED_FILE_IO
+
+```cpp
+#define JSON_DISABLE_UNLOCKED_FILE_IO /* value */
+```
+
+When defined to `1`, parsing from a `#!cpp FILE*` reads every character with `std::fgetc`, as in version 3.12.0 and
+earlier, instead of locking the file once and reading it with the unlocked stdio functions.
+
+It does not change any result: values, exceptions, and the position of the file after parsing are the same either way.
+Only the speed and the locking of the file differ (see the notes on locking below).
+
+## Default definition
+
+The default value is `0`: the file is locked once and read with the unlocked stdio functions where they are available.
+
+```cpp
+#define JSON_DISABLE_UNLOCKED_FILE_IO 0
+```
+
+## Notes
+
+!!! note "Background"
+
+    The C standard library makes every `std::fgetc` call thread-safe by locking and unlocking the `FILE` object. When
+    parsing from a `FILE*`, the parser reads one character at a time, so this happens for every character of the input.
+
+    Instead, the parser locks the file once when parsing starts and unlocks it when parsing ends - also when an
+    exception is thrown - and reads the characters in between without locking:
+
+    | C library                                                  | functions                                          |
+    |------------------------------------------------------------|----------------------------------------------------|
+    | glibc (Linux), Apple (macOS, iOS), Android, FreeBSD, NetBSD, OpenBSD, DragonFly BSD | `flockfile`, `getc_unlocked`, `funlockfile` (POSIX) |
+    | Microsoft (MSVC, clang-cl)                                 | `_lock_file`, `_fgetc_nolock`, `_unlock_file`       |
+    | others (e.g., musl, MinGW, newlib)                         | `std::fgetc`, as before                             |
+
+    This makes parsing from a `FILE*` 3 to 4 times as fast with the Apple C library and 1.1 to 1.3 times as fast with
+    glibc, whose locking is cheaper. The binary formats ([`from_cbor`](../basic_json/from_cbor.md),
+    [`from_msgpack`](../basic_json/from_msgpack.md), ...) read from a `FILE*` the same way.
+
+!!! note "Locking"
+
+    While a value is parsed from a `FILE*`, the parsing thread holds the file's lock. The lock is recursive, so the
+    parsing thread itself - for instance, a [SAX](../json_sax/index.md) handler or a
+    [parser callback](../basic_json/parser_callback_t.md) - can keep using the file with stdio functions such as
+    `std::ftell`. Other threads that use the same `FILE` object wait until the parser is done. Before, they could
+    interleave their reads with the parser's, which made the parsed input unpredictable anyway.
+
+    A program in which a SAX handler or parser callback waits for **another** thread that uses the **same** `FILE`
+    object would deadlock. Define the macro to `1` for such programs.
+
+!!! warning "Define consistently"
+
+    The macro selects between two definitions of the library's internal `FILE*` input adapter. It must therefore be
+    defined identically for **every** translation unit that includes the library; mixing translation units that define
+    it with ones that do not is an ODR violation (and can leave a file locked). Prefer setting it as a compile
+    definition on the target rather than with `#!cpp #define` in individual source files.
+
+!!! note "Other inputs"
+
+    Reading from a `#!cpp std::istream` is not affected by this macro; see
+    [`JSON_DISABLE_STREAM_BULK_SCAN`](json_disable_stream_bulk_scan.md) for that input.
+
+## Examples
+
+??? example "Example: parsing from a `FILE*` (default)"
+
+    The file is locked once while it is parsed:
+
+    ```cpp
+    #include <cstdio>
+    #include <nlohmann/json.hpp>
+
+    using json = nlohmann::json;
+
+    int main()
+    {
+        std::FILE* f = std::fopen("example.json", "rb");
+        json j = json::parse(f);  // f is locked until parse() returns
+        std::fclose(f);
+    }
+    ```
+
+??? example "Example: locking for every character (macro defined to 1)"
+
+    With the macro, every character is read with `std::fgetc`, with the same result:
+
+    ```cpp
+    #define JSON_DISABLE_UNLOCKED_FILE_IO 1
+    #include <cstdio>
+    #include <nlohmann/json.hpp>
+
+    using json = nlohmann::json;
+
+    int main()
+    {
+        std::FILE* f = std::fopen("example.json", "rb");
+        json j = json::parse(f);  // std::fgetc for every character
+        std::fclose(f);
+    }
+    ```
+
+## See also
+
+- [**parse**](../basic_json/parse.md) - deserialize from a compatible input
+- [**sax_parse**](../basic_json/sax_parse.md) - generate SAX events
+- [**JSON_DISABLE_STREAM_BULK_SCAN**](json_disable_stream_bulk_scan.md) - read a `std::istream` one character at a
+  time
+- [Parsing: input sources and performance](../../features/parsing/index.md#input-sources-and-performance)
+
+## Version history
+
+- Added in version 3.13.0.
@@ -72,6 +72,12 @@ The default value is `0` (disabled — existing behavior is preserved).
    distinct symbol names. Translation units compiled with and without it can therefore be linked into the same program
    without One Definition Rule (ODR) violations, but they cannot exchange instances of library types.

+!!! note "Bulk scanning"
+
+    The parser scans the characters in the stream buffer in bulk (see
+    [`JSON_DISABLE_STREAM_BULK_SCAN`](json_disable_stream_bulk_scan.md)), but it never reads ahead. The stream is left
+    at the same position with and without bulk scanning, in both modes of this macro.
+
 !!! tip "Workaround without the macro"

    Separate the values in the stream with whitespace. The character consumed after a number is then the separator,
@@ -18,8 +18,7 @@ When enabled, comparisons involving at least one discarded JSON value yield resu
 | `>=`         | `#!cpp true`  |
 | `>`          | `#!cpp false` |

-Otherwise, comparisons involving at least one discarded JSON value yield `#!cpp false`, except for `!=`, which is the
-negation of `==` and yields `#!cpp true`.
+Otherwise, comparisons involving at least one discarded JSON value always yield `#!cpp false`.

 ## Default definition

@@ -12,8 +12,9 @@ non-ASCII characters (e.g. CJK or emoji) this can validate several times faster.
 This is an **opt-in external dependency**. The library itself remains header-only and its behavior is unchanged: the
 same input is accepted or rejected either way, and every parse error is reported at the same position with the same
 message (simdutf is only used to fast-path *valid* runs; anything it flags falls back to the scalar path so the exact
-diagnostic is preserved). Streaming inputs (files, `std::istream`, wide strings, user-defined adapters) always use the
-scalar path.
+diagnostic is preserved). A `std::istream` uses simdutf for the characters its stream buffer holds (see
+[`JSON_DISABLE_STREAM_BULK_SCAN`](json_disable_stream_bulk_scan.md)); other streaming inputs (`FILE*`, wide strings,
+user-defined adapters) always use the scalar path.

 When `JSON_USE_SIMDUTF` is defined you must make the `simdutf.h` header available on the include path and link the
 simdutf library. When it is not defined, no simdutf header is included and there is no dependency.
@@ -121,6 +121,7 @@ being read.
 - [`JSON_STRICT_NUL_HANDLING`](macros/json_strict_nul_handling.md) - opt in to rejecting a NUL byte in the input
  instead of treating it as end of input
 - [`JSON_PRECISE_STREAM_POSITION`](macros/json_precise_stream_position.md) - opt in to leaving the stream positioned right after a number
+- [`JSON_DISABLE_STREAM_BULK_SCAN`](macros/json_disable_stream_bulk_scan.md) - read the stream one character at a time

 ## Version history

@@ -133,3 +134,6 @@ being read.
  crash (`std::terminate`) when `i` has `eofbit` in its exception mask, in version 3.13.0.
 - Changed to the strong exception safety guarantee in version 3.13.0: `j` is no longer left with a partially parsed
  value if parsing throws.
+- Scans the characters in the stream buffer of `i` in bulk in version 3.13.0; the position of `i` after the call is
+  unchanged ([`JSON_DISABLE_STREAM_BULK_SCAN`](macros/json_disable_stream_bulk_scan.md) restores reading one character
+  at a time).
@@ -54,9 +54,10 @@ flowchart LR
  user code. The destructor does not recurse, so destroying a deeply nested value does not exhaust the stack.
 - **Bounded recursion.** The JSON parser and the binary readers keep their state in explicit stacks instead of
  recursing per nesting level. Operations that walk a value, such as [`dump`](../api/basic_json/dump.md), copying,
-  comparison, hashing, [`merge_patch`](../api/basic_json/merge_patch.md), [`diff`](../api/basic_json/diff.md),
-  [`flatten`](../api/basic_json/flatten.md), and the binary writers, recurse only up to a fixed depth and continue with
-  an explicit stack below it. Applications that process untrusted input can limit its nesting depth with a
+  comparison, hashing, and [`merge_patch`](../api/basic_json/merge_patch.md), recurse only up to a fixed depth and
+  continue with an explicit stack below it. Some operations, such as [`diff`](../api/basic_json/diff.md),
+  [`flatten`](../api/basic_json/flatten.md), and the binary writers, still recurse once per nesting level; work on them
+  is in progress. Applications that process untrusted input can limit its nesting depth with a
  [parser callback](../features/parsing/parser_callbacks.md).
 - **Invariants are checked.** The class invariant (for instance, that the pointer for the stored type is never null) is
  checked with runtime assertions throughout the test suite.
@@ -267,10 +267,9 @@ unsigned 8-bit integer. If no subtype is given, the generic binary subtype 0x00

 ### CBOR

-[CBOR](binary_formats/cbor.md) supports binary values and subtypes. Any binary value will be serialized as a byte
-string; a subtype is serialized as a tag preceding it. When parsing, tags are only read back as subtypes with
-`cbor_tag_handler_t::store` (see [`from_cbor`](../api/basic_json/from_cbor.md)). The library will choose the smallest
-representation using the length of the byte array.
+[CBOR](binary_formats/cbor.md) supports binary values, but no subtypes. Subtypes will be serialized as tags. Any binary
+value will be serialized as byte strings. The library will choose the smallest representation using the length of the
+byte array.

 ??? example "Example: serialize a binary value to CBOR"

@@ -133,6 +133,14 @@ When defined, default parse and serialize functions for enums are excluded and h

 See [full documentation of `JSON_DISABLE_ENUM_SERIALIZATION`](../api/macros/json_disable_enum_serialization.md).

+## `JSON_DISABLE_STREAM_BULK_SCAN`
+
+When defined to `1`, parsing from a `#!cpp std::istream` reads one character at a time instead of scanning the
+characters that the stream buffer holds in bulk. Results are the same either way; the macro is an escape hatch for
+stream buffers that do not follow the usual `std::streambuf` contract. The default value is `0`.
+
+See [full documentation of `JSON_DISABLE_STREAM_BULK_SCAN`](../api/macros/json_disable_stream_bulk_scan.md).
+
 ## `JSON_DISABLE_TUPLE_REFERENCE_CONVERSION`

 When defined to `1`, a JSON value can no longer be created from a one-element `std::tuple` holding a reference to a JSON
@@ -141,6 +149,14 @@ is planned to become the default in version 4.0.0.

 See [full documentation of `JSON_DISABLE_TUPLE_REFERENCE_CONVERSION`](../api/macros/json_disable_tuple_reference_conversion.md).

+## `JSON_DISABLE_UNLOCKED_FILE_IO`
+
+When defined to `1`, parsing from a `#!cpp FILE*` reads every character with `std::fgetc`, which locks the file each
+time, instead of locking the file once and reading it with the unlocked stdio functions. Results are the same either
+way. The default value is `0`.
+
+See [full documentation of `JSON_DISABLE_UNLOCKED_FILE_IO`](../api/macros/json_disable_unlocked_file_io.md).
+
 ## `JSON_NO_AUTOMATIC_UDLS`

 When defined, `<nlohmann/json.hpp>` does not include `<nlohmann/json_literals.hpp>` with the user-defined string literals
@@ -243,9 +259,9 @@ See [full documentation of `JSON_USE_GLOBAL_UDLS`](../api/macros/json_use_global

 ## `JSON_USE_LEGACY_DISCARDED_VALUE_COMPARISON`

-When defined to `1`, the library restores the legacy behavior in which comparing a discarded value with `<=` or `>=`
-yields `#!cpp true` instead of `#!cpp false`. This behavior is
-[deprecated](../integration/migration_guide.md#miscellaneous-functions) and switched off (`0`) by default.
+When defined to `1`, the library restores the legacy behavior in which a discarded value compared equal to itself. This
+behavior is [deprecated](../integration/migration_guide.md#miscellaneous-functions) and switched off (`0`) by
+default.

 See [full documentation of `JSON_USE_LEGACY_DISCARDED_VALUE_COMPARISON`](../api/macros/json_use_legacy_discarded_value_comparison.md).

@@ -1,6 +1,6 @@
 # JSON Merge Patch

-The library supports JSON Merge Patch ([RFC 7396](https://tools.ietf.org/html/rfc7396)) as a patch format.
+The library supports JSON Merge Patch ([RFC 7386](https://tools.ietf.org/html/rfc7386)) as a patch format.
 The merge patch format is primarily intended for use with the HTTP PATCH method as a means of describing a set of
 modifications to a target resource's content. This function applies a merge patch to the current JSON value.

@@ -66,7 +66,7 @@ config.update(user_settings, true);
 // {"log":{"file":"app.log","level":"debug"},"retries":3}
 ```

-[JSON Merge Patch](merge_patch.md) ([RFC 7396](https://tools.ietf.org/html/rfc7396)) also merges objects recursively,
+[JSON Merge Patch](merge_patch.md) ([RFC 7386](https://tools.ietf.org/html/rfc7386)) also merges objects recursively,
 but it is a different tool: a `#!json null` in the patch means "remove this key". It is meant for applying merge patch
 documents (e.g., received via HTTP PATCH). To merge configuration-like objects, use `#!cpp update(..., true)`. To apply
 a sequence of well-defined edit operations, see [JSON Patch](json_patch.md).
@@ -90,6 +90,6 @@ a.erase(1);             // [1,3,4]  (erase by index)
 - [`push_back`](../api/basic_json/push_back.md) / [`emplace_back`](../api/basic_json/emplace_back.md) - append to an array
 - [`emplace`](../api/basic_json/emplace.md) - insert into an object if the key is absent
 - [`update`](../api/basic_json/update.md) - merge objects (shallow, or recursive with `merge_objects`)
- [`merge_patch`](../api/basic_json/merge_patch.md) - apply an RFC 7396 merge patch
+- [`merge_patch`](../api/basic_json/merge_patch.md) - apply an RFC 7386 merge patch
 - [`erase`](../api/basic_json/erase.md) / [`clear`](../api/basic_json/clear.md) - remove elements
 - [JSON Patch and Diff](json_patch.md) and [JSON Merge Patch](merge_patch.md) - structured modifications
@@ -55,6 +55,30 @@ whitespace, because `operator>>` consumes the character that terminates a number
 [`JSON_PRECISE_STREAM_POSITION`](../../api/macros/json_precise_stream_position.md) is defined to `1` — see the
 [`operator>>` notes](../../api/operator_gtgt.md#notes) for details and examples.

+## Input sources and performance
+
+All inputs produce the same values and the same exceptions, but they are read in different ways, which makes some of
+them faster than others:
+
+| input                                                                                      | how it is read                                                                     |
+|--------------------------------------------------------------------------------------------|------------------------------------------------------------------------------------|
+| strings, string views, string literals, contiguous containers, pointer or iterator ranges over contiguous memory | the whole input is scanned in bulk: runs of string characters, numbers, and indentation are recognized several bytes at a time |
+| `#!cpp std::istream` (`#!cpp std::ifstream`, `#!cpp std::istringstream`, ...)            | the characters the stream buffer holds are scanned in bulk like a string; the stream buffer is asked for more when they are used up |
+| `#!cpp FILE*`                                                                              | one character at a time, with the file locked once for the whole parse              |
+| other iterator ranges (e.g., `#!cpp std::list<char>`, `#!cpp std::istreambuf_iterator<char>`), wide strings | one character at a time                                                             |
+
+Parsing a file from a `#!cpp std::ifstream` is therefore only about 10 to 20 % slower than reading the whole file into a
+`#!cpp std::string` first and parsing that, and it needs no memory for a copy of the file. The stream is never read
+ahead: after parsing, it is positioned exactly as if every character had been read one at a time, so
+[`operator>>`](../../api/operator_gtgt.md) can still read several values from one stream (see also
+[JSON Lines](json_lines.md)).
+
+Two macros switch these optimizations off without changing any result:
+[`JSON_DISABLE_STREAM_BULK_SCAN`](../../api/macros/json_disable_stream_bulk_scan.md) for stream buffers that do not
+follow the usual `std::streambuf` contract, and
+[`JSON_DISABLE_UNLOCKED_FILE_IO`](../../api/macros/json_disable_unlocked_file_io.md) for programs in which another
+thread must use the same `#!cpp FILE` object while it is parsed.
+
 ## SAX vs. DOM parsing

 The library offers two parsing models:
@@ -50,13 +50,19 @@ stack, however deeply it is nested.

 Once a value has been parsed, operations that walk it recursively -- serializing it with
 [`dump`](../../api/basic_json/dump.md), hashing it, copying it, comparing two values with `#!cpp ==`, `#!cpp <`, or (in
-C++20) `#!cpp <=>`, merging with [`update`](../../api/basic_json/update.md), applying a
-[`merge_patch`](../../api/basic_json/merge_patch.md), creating a patch with [`diff`](../../api/basic_json/diff.md) or
-[`merge_diff`](../../api/basic_json/merge_diff.md), [`flatten`](../../api/basic_json/flatten.md), and the binary
-writers (`to_cbor`, `to_msgpack`, ...) -- descend at most 128 levels on the call stack and continue
+C++20) `#!cpp <=>`, merging with [`update`](../../api/basic_json/update.md), and applying a
+[`merge_patch`](../../api/basic_json/merge_patch.md) -- descend at most 128 levels on the call stack and continue
 below that with an explicit stack instead, so none of them can exhaust the stack either, however deeply the value is
 nested. Destroying a value (its destructor) never recurses at all, regardless of nesting depth, for the same reason.

+!!! note "Not every operation is bounded yet"
+
+    [`diff`](../../api/basic_json/diff.md), [`flatten`](../../api/basic_json/flatten.md), and the binary writers
+    (`to_cbor`, `to_msgpack`, ...) still recurse once per nesting level; this is called out as work in progress in the
+    [assurance case](../../community/assurance_case.md#secure-design). A value deep enough to matter for these
+    operations would typically first have to survive parsing without hitting a self-imposed depth limit, as described
+    above.
+
 ## Input size

 The library does not limit the overall size of a JSON text; a value nested or wide enough will use memory
@@ -52,7 +52,7 @@ with `\uXXXX` sequences, so that the output contains only ASCII characters:
 ```cpp
 json j = "苹果";
 j.dump();               // "苹果"
-j.dump(-1, ' ', true);  // "\u82f9\u679c"
+j.dump(-1, ' ', true);  // "苹果"
 ```

 ## Handling invalid UTF-8
@@ -281,7 +281,7 @@ As this range is a subrange of the exactly supported range [`INT64_MIN`, `INT64_

 > This specification allows implementations to set limits on the range and precision of numbers accepted. Since software that implements IEEE 754-2008 binary64 (double precision) numbers is generally available and widely used, good interoperability can be achieved by implementations that expect no more precision or range than these provide, in the sense that implementations will approximate JSON numbers within the expected precision.

-This implementation does exactly follow this approach, as it uses double precision floating-point numbers. Note that numbers smaller than `#!c -1.79769313486232e+308` or greater than `#!c 1.79769313486232e+308` are rejected during parsing with [`out_of_range.406`](../../home/exceptions.md#jsonexceptionout_of_range406). Non-finite values (NaN and infinity) can only be stored by assigning them directly and are serialized to `#!json null`.
+This implementation does exactly follow this approach, as it uses double precision floating-point numbers. Note values smaller than `#!c -1.79769313486232e+308` and values greater than `#!c 1.79769313486232e+308` will be stored as NaN internally and be serialized to `#!json null`.

 ### Storage

@@ -82,13 +82,12 @@ flowchart TD

    - Numbers with a decimal digit or scientific notation are always stored as `#!c double`.
    - The number types can be changed, see [Template number types](#template-number-types). 
-    - The library converts integers and floating-point numbers itself, independent of the locale. Floating-point
-      numbers are correctly rounded (to nearest, ties to even). Only a `#!c long double` that is not IEEE 754 binary64
-      (e.g., the 80-bit x87 format) is converted with `#!cpp std::from_chars` where available, or else with
-      [`std::strtold`](https://en.cppreference.com/w/cpp/string/byte/strtof). For that call, the library temporarily
-      replaces the `.` with the decimal point of the current locale (which may be longer than one byte, e.g., in
-      `fa_IR.UTF-8`), so the result does not depend on the locale either. Changing the locale in another thread during
-      parsing is undefined behavior of the C library, though. Before version 3.13.0, the conversion was realized by
+    - Integers are converted by the library's own digit parser. Floating-point numbers are converted with
+      [`std::from_chars`](https://en.cppreference.com/w/cpp/utility/from_chars) if the library is compiled with C++17
+      and the standard library supports it, then with an exact fast path for `#!c double` values with few significant
+      digits, and otherwise with the locale-aware
+      [`std::strtod`](https://en.cppreference.com/w/cpp/string/byte/strtof) (`std::strtof`/`std::strtold` for the
+      other floating-point types). Before version 3.13.0, the conversion was realized by
      [`std::strtoull`](https://en.cppreference.com/w/cpp/string/byte/strtoul),
      [`std::strtoll`](https://en.cppreference.com/w/cpp/string/byte/strtol), and `std::strtod`, respectively.

@@ -101,10 +100,10 @@ flowchart TD
 ### Number limits

 - Any 64-bit signed or unsigned integer can be stored without loss of precision.
- Numbers exceeding the limits of `#!c double` (i.e., numbers whose rounded value is not satisfying
+- Numbers exceeding the limits of `#!c double` (i.e., numbers that after conversion via
+[`std::strtod`](https://en.cppreference.com/w/cpp/string/byte/strtof) are not satisfying
 [`std::isfinite`](https://en.cppreference.com/w/cpp/numeric/math/isfinite) such as `#!c 1E400`) will throw exception
-[`json.exception.out_of_range.406`](../../home/exceptions.md#jsonexceptionout_of_range406) during parsing. Numbers too
-small for `#!c double` (such as `#!c 1E-400`) become zero, with the sign of the number.
+[`json.exception.out_of_range.406`](../../home/exceptions.md#jsonexceptionout_of_range406) during parsing.
 - Floating-point numbers are rounded to the next number representable as `double`. For instance
 `#!c 3.141592653589793238462643383279` is stored as [`0x400921fb54442d18`](https://float.exposed/0x400921fb54442d18).
 This is the same behavior as the code `#!c double x = 3.141592653589793238462643383279;`.
@@ -134,10 +133,9 @@ That is, `-0` is stored as a signed integer, but the serialization does not repr
 ### Number serialization

 - Integer numbers are serialized as is; that is, no scientific notation is used.
- Floating-point numbers are serialized with the fewest digits that read back as the same value (the closest such
-  digits if there are several), in the layout of the `#!c %g` printf modifier: `#!c 1.5`, `#!c 100.0`, `#!c 1e+100`.
-  Doubles are converted with the algorithm of [Żmij](https://github.com/vitaut/zmij), floats with Grisu2, which
-  can write more digits than necessary.
+- Floating-point numbers are serialized as specified by the `#!c %g` printf modifier with 
+  [`std::numeric_limits<double>::max_digits10`](https://en.cppreference.com/w/cpp/types/numeric_limits/max_digits10)
+  significant digits. The rationale is to use the shortest representation while still allowing round-tripping.

 !!! hint "Notes regarding precision of floating-point numbers"

@@ -30,9 +30,9 @@ Requirements are split into two groups:
    diagnosed with dedicated error messages, and violating most of them results in a compiler error somewhere inside
    the library. Four violations are not caught at compile time at all:

-    - A [`StringType`](#stringtype) whose `data()` is not null-terminated compiles and silently misparses numbers
-      stored as a `#!cpp long double` that is not IEEE 754 binary64 (e.g., the 80-bit x87 format), because the lexer
-      hands the buffer to `#!cpp std::strtold`.
+    - A [`StringType`](#stringtype) whose `data()` is not null-terminated compiles and can silently misparse
+      floating-point numbers, because the lexer may hand the buffer to `#!cpp std::strtod`, which reads up to the
+      terminating null character.
    - A stateful [`AllocatorType`](#allocatortype) compiles and silently ignores its state: allocation, deallocation,
      and [`get_allocator()`](../../api/basic_json/get_allocator.md) each use a different default-constructed instance.
    - The two [cross-specialization conversions](#cross-specialization-conversions) below. These abort on an assertion
@@ -353,21 +353,16 @@ using array_t = ArrayType<basic_json, AllocatorType<basic_json>>;
 ### Always required

 - A member type `value_type` that is one byte wide and `char`-compatible. The library stores and processes UTF-8
-  encoded `char` data and passes `data()` to functions that take a `#!cpp const char*`, such as `#!cpp std::strtold`
-  (only used to parse a `#!cpp long double` that is not IEEE 754 binary64, see
-  [`NumberFloatType`](#numberfloattype)).
+  encoded `char` data and passes `data()` to functions that take a `#!cpp const char*`, such as `#!cpp std::strtod`.
  `#!cpp std::wstring`, `#!cpp std::u16string`, and `#!cpp std::u32string` are **not** valid choices; see the FAQ on
  [wide string handling](../../home/faq.md#wide-string-handling).
 - Constructors: default, copy, move, from `#!cpp const char*` (which must not be `#!cpp explicit`), from
  `#!cpp (const char*, size_type)`, and from `#!cpp (size_type, char)`; and copy or move assignment.
 - Member functions `size()`, `clear()`, `resize(n, c)`, `data()`, `push_back(char)`, and `operator[]`
  (const and non-const, returning references). `c_str()` and `back()` are **not** required.
- `data()` must return a pointer to a contiguous, **null-terminated** buffer. `#!cpp float`, `#!cpp double`, and a
-  `#!cpp long double` that is IEEE 754 binary64 are converted by the library itself and do not depend on this. For any
-  other `NumberFloatType` (a `#!cpp long double` of another format), the parser falls back to `#!cpp std::strtold` when
-  `#!cpp std::from_chars` is not available or declines the token, and `std::strtold` reads up to the null character. A type whose `data()`
-  is not null-terminated does not fail to compile; with such a `NumberFloatType` it can silently misparse
-  floating-point numbers.
+- `data()` must return a pointer to a contiguous, **null-terminated** buffer -- the parser may hand it to
+  `#!cpp std::strtod`, which reads up to the null character. A type whose `data()` is not null-terminated does not
+  fail to compile; it can silently misparse floating-point numbers.
 - `append(const char*, size_type)`, used by [`dump`](../../api/basic_json/dump.md), and `append(const StringType&)`,
  used by the CBOR reader for indefinite-length strings. The library's internal string concatenation additionally has
  to append a `#!cpp char` and a `#!cpp const char*`; for each it selects between `append(arg)`, `#!cpp operator+=`,
@@ -546,18 +541,16 @@ therefore silently changes parse results rather than raising an error. See

 `NumberFloatType` must be one of `#!cpp float`, `#!cpp double`, or `#!cpp long double`:

- The [parser](../parsing/index.md) converts number literals to `#!cpp float`, `#!cpp double`, and a
-  `#!cpp long double` that is IEEE 754 binary64 itself; other `#!cpp long double` formats are converted with
-  `#!cpp std::from_chars` where available, or with `#!cpp std::strtold`. The library provides overloads for exactly
-  these three types.
+- The [parser](../parsing/index.md) converts number literals with `#!cpp std::from_chars` or, as a fallback, with
+  `#!cpp std::strtof`, `#!cpp std::strtod`, or `#!cpp std::strtold`; the library provides overloads for exactly these
+  three types.
 - [`dump`](../../api/basic_json/dump.md) falls back to `#!cpp std::snprintf` with the `%g` and `%Lg` conversion
  specifiers, for which the library likewise provides only `#!cpp double` and `#!cpp long double` overloads
  (`#!cpp float` is promoted to `#!cpp double`).

-If `#!cpp std::numeric_limits<NumberFloatType>` describes an IEEE 754 binary64 number, `dump` uses the algorithm of
-Żmij, which produces the shortest representation that round-trips. For IEEE 754 binary32 numbers, it uses Grisu2,
-which produces a short representation that round-trips. Otherwise the `snprintf` fallback with `max_digits10` digits is
-used.
+If `#!cpp std::numeric_limits<NumberFloatType>` describes an IEEE 754 binary32 or binary64 number, `dump` uses the
+Grisu2 algorithm, which produces the shortest representation that round-trips. Otherwise the `snprintf` fallback with
+`max_digits10` digits is used.

 ### Required for the binary formats

@@ -569,7 +562,7 @@ binary32 or binary64 field and have no encoding for `#!cpp long double`.

 | Type                     | Support                                                                                                               |
 |--------------------------|-----------------------------------------------------------------------------------------------------------------------|
-| `#!cpp double` (default) | full; shortest round-trip output through Żmij                                                                         |
+| `#!cpp double` (default) | full; short round-trip output through Grisu2                                                                          |
 | `#!cpp float`            | full; short round-trip output through Grisu2                                                                          |
 | `#!cpp long double`      | `dump` and `parse` only; the binary format writers do not compile, as they only handle IEEE 754 binary32 and binary64 |
 | any other type           | not usable                                                                                                            |
@@ -889,9 +889,7 @@ contains other characters (e.g., `1a`), or `-` where it cannot be used.

 ### json.exception.out_of_range.405

-The JSON Patch operations 'remove' and 'move' cannot be applied to the root element of the JSON value. The exception is
-also thrown when the parent or a reference token of an empty JSON Pointer is requested, for instance by
-[`back`](../api/json_pointer/back.md) or [`pop_back`](../api/json_pointer/pop_back.md).
+The JSON Patch operations 'remove' and 'add' cannot be applied to the root element of the JSON value.

 !!! failure "Example message"

@@ -916,23 +914,15 @@ double-precision number when `number_float_t` is `#!cpp float`.

 ### json.exception.out_of_range.407

-An unsigned integer number greater than 9223372036854775807 cannot be represented in the binary format. This exception
-is only thrown by [`to_bon8`](../api/basic_json/to_bon8.md), as [BON8](../features/binary_formats/bon8.md) has no
-unsigned 64-bit integer type.
+This exception previously indicated that the UBJSON and BSON binary formats did not support integer numbers greater than
+9223372036854775807 due to limitations in the implemented mapping. However, these limitations have since been resolved,
+and this exception no longer occurs.

-!!! note "Former occurrences"
-
-    The UBJSON and BSON writers used to throw this exception as well:
+!!! success "Exception cannot occur any more"

    - Since version 3.9.0, integer numbers beyond int64 are serialized as high-precision UBJSON numbers.
    - Since version 3.12.0, integer numbers beyond int64 are serialized as uint64 BSON numbers.

-!!! failure "Example message"
-
-    ```
-    integer number 18446744073709551615 cannot be represented by BON8 as it does not fit int64
-    ```
-
 ### json.exception.out_of_range.408

 The size of an array or object in a [binary format](../features/binary_formats/index.md) exceeds the maximal capacity:
@@ -66,9 +66,7 @@ Without the macro (default behavior), `json j{obj}` creates `[{"key":"value"}]`.

    Can you add an option to ignore trailing commas?

-Yes, trailing commas in arrays and objects can be allowed by setting parameter `ignore_trailing_commas` of
-[`parse`](../api/basic_json/parse.md) to `#!cpp true`; see [trailing commas](../features/trailing_commas.md). They are
-rejected by default, and the library never adds them when serializing.
+This library does not support any feature that would jeopardize interoperability.


 ### Parse errors reading non-ASCII characters
@@ -232,11 +230,11 @@ Yes, you can. Please define the symbol [`JSON_DIAGNOSTICS`](../api/macros/json_d
    - It seems that precision is lost when serializing a double.
    - Can I change the precision for floating-point serialization?

-The library serializes floating-point numbers with the shortest representation that parses back to the same value, using at most `std::numeric_limits<number_float_t>::max_digits10` (17 for IEEE `double`s) significant digits. This guarantees that value -> string -> value round-trips. The reverse direction, string -> value -> string, is only guaranteed for numbers with at most `std::numeric_limits<number_float_t>::digits10` (15 for IEEE `double`s) significant digits; a number with more digits may not be representable exactly and is then serialized as the closest `double`.
+The library uses `std::numeric_limits<number_float_t>::digits10` (15 for IEEE `double`s) digits for serialization. This value is sufficient to guarantee roundtripping. If one uses more than this number of digits of precision, then string -> value -> string is not guaranteed to round-trip.

-!!! quote "[cppreference.com](https://en.cppreference.com/w/cpp/types/numeric_limits/max_digits10)"
+!!! quote "[cppreference.com](https://en.cppreference.com/w/cpp/types/numeric_limits/digits10)"

-    The value of `std::numeric_limits<T>::max_digits10` is the number of base-10 digits that are necessary to uniquely represent all distinct values of the type T, such as necessary for serialization/deserialization to text.
+    The value of `std::numeric_limits<T>::digits10` is the number of base-10 digits that can be represented by the type T without change, that is, any number with this many significant decimal digits can be converted to a value of type T and back to decimal form, without change due to rounding or overflow. 

 !!! tip

@@ -18,8 +18,6 @@ The class contains the UTF-8 Decoder from Bjoern Hoehrmann which is licensed und

 The class contains a slightly modified version of the Grisu2 algorithm from Florian Loitsch which is licensed under the [MIT License](https://opensource.org/licenses/MIT) (see above). Copyright &copy; 2009 [Florian Loitsch](https://florian.loitsch.com/)

-The class contains a port of the shortest double-to-decimal conversion of [Żmij](https://github.com/vitaut/zmij) by Victor Zverovich, including the conversion of the digits to text by Xiang JunBo and the SIMD instruction sequence of Dougall Johnson, which is licensed under the [MIT License](https://opensource.org/licenses/MIT) (see above). Copyright &copy; 2025 [Victor Zverovich](https://github.com/vitaut)
-
 The class contains a copy of [Hedley](https://nemequ.github.io/hedley/) from Evan Nemerson which is licensed as [CC0-1.0](https://creativecommons.org/publicdomain/zero/1.0/).

-The class contains an adapted version of the Eisel-Lemire algorithm, its table of powers of five, and its digit comparison for long numbers from [fast_float](https://github.com/fastfloat/fast_float) by Daniel Lemire and contributors, which is available under the [MIT License](https://opensource.org/licenses/MIT) (used here), the Apache 2.0 License, and the Boost Software License. Copyright &copy; 2021 The fast_float authors
+The class contains an adapted version of the Eisel-Lemire algorithm and its table of powers of five from [fast_float](https://github.com/fastfloat/fast_float) by Daniel Lemire and contributors, which is available under the [MIT License](https://opensource.org/licenses/MIT) (used here), the Apache 2.0 License, and the Boost Software License. Copyright &copy; 2021 The fast_float authors
@@ -90,13 +90,13 @@ to the following.

 ### FetchContent

-Since CMake v3.14, [FetchContent](https://cmake.org/cmake/help/v3.14/module/FetchContent.html) can be used to
+Since CMake v3.11, [FetchContent](https://cmake.org/cmake/help/v3.11/module/FetchContent.html) can be used to
 automatically download a release as a dependency at configure time.

 !!! example

    ```cmake title="CMakeLists.txt"
-    cmake_minimum_required(VERSION 3.14)
+    cmake_minimum_required(VERSION 3.11)
    project(ExampleProject LANGUAGES CXX)

    include(FetchContent)
@@ -14,8 +14,7 @@ that cost, ordered by how much they typically save.

 Header files that only need to *name* the `json` type — for function declarations, members held by pointer or
 reference, or friend declarations — can include `<nlohmann/json_fwd.hpp>` instead of `<nlohmann/json.hpp>`. It only
-forward-declares `basic_json`, `json_pointer`, `adl_serializer`, and `ordered_map`, and defines the aliases `json` and
-`ordered_json`. The translation units that
+forward-declares `basic_json`, `json`, `ordered_json`, `json_pointer`, and `adl_serializer`. The translation units that
 actually use the values then include `<nlohmann/json.hpp>`.

 ```cpp title="person.hpp"
@@ -297,7 +297,9 @@ nav:
          - 'JSON_DELETE_DEPRECATED_FUNCTIONS': api/macros/json_delete_deprecated_functions.md
          - 'JSON_DIAGNOSTIC_POSITIONS': api/macros/json_diagnostic_positions.md
          - 'JSON_DISABLE_ENUM_SERIALIZATION': api/macros/json_disable_enum_serialization.md
+          - 'JSON_DISABLE_STREAM_BULK_SCAN': api/macros/json_disable_stream_bulk_scan.md
          - 'JSON_DISABLE_TUPLE_REFERENCE_CONVERSION': api/macros/json_disable_tuple_reference_conversion.md
+          - 'JSON_DISABLE_UNLOCKED_FILE_IO': api/macros/json_disable_unlocked_file_io.md
          - 'JSON_HAS_CPP_11, JSON_HAS_CPP_14, JSON_HAS_CPP_17, JSON_HAS_CPP_20, JSON_HAS_CPP_23, JSON_HAS_CPP_26': api/macros/json_has_cpp_11.md
          - 'JSON_HAS_EXPERIMENTAL_FILESYSTEM, JSON_HAS_FILESYSTEM': api/macros/json_has_filesystem.md
          - 'JSON_HAS_RANGE_VIEW_CONVERSION': api/macros/json_has_range_view_conversion.md
@@ -453,12 +455,8 @@ plugins:
      # package badges (the fetch fails, then reading the missing cache entry
      # raises FileNotFoundError). Readers' browsers are served normally, so
      # leave these badges as external references instead of self-hosting them.
-      # The same goes for img.shields.io, whose version badges time out from
-      # time to time (strict mode turns the failed download into an error) and
-      # would go stale between builds if they were self-hosted anyway.
      assets_exclude:
        - repology.org/*
-        - img.shields.io/*
  - llmstxt:
      markdown_description: >
        JSON for Modern C++ is a C++11 header-only library implementing a JSON
@@ -7,6 +7,6 @@ mkdocs-material-extensions==1.3.1                   # extensions
 mkdocs-minify-plugin==0.8.0                         # plugin "minify"
 mkdocs-redirects==1.2.3                             # plugin "redirects"
 mkdocs-htmlproofer-plugin==1.6.0                    # plugin "htmlproofer"
-mkdocs-llmstxt==0.5.1                               # plugin "llmstxt"
+mkdocs-llmstxt==0.5.0                               # plugin "llmstxt"

 PyYAML==6.0.3                                       # linter
@@ -6,7 +6,7 @@
    "": {
      "name": "check-mermaid",
      "dependencies": {
-        "jsdom": "30.1.2",
+        "jsdom": "30.1.1",
        "mermaid": "11.17.2"
      }
    },
@@ -24,14 +24,14 @@
      }
    },
    "node_modules/@asamuzakjp/css-color": {
-      "version": "7.1.3",
-      "resolved": "https://registry.npmjs.org/@asamuzakjp/css-color/-/css-color-7.1.3.tgz",
-      "integrity": "sha512-1t1U8Cm3RBl9vh3RAZhjkPaduzLSvQJRToRrxpGR/eDRW99mOREleuu+mWfiFa795bUzjwht7NgphCKTs2ianQ==",
+      "version": "7.1.2",
+      "resolved": "https://registry.npmjs.org/@asamuzakjp/css-color/-/css-color-7.1.2.tgz",
+      "integrity": "sha512-99DHAnXDB5z6EEK+9GMpVI7Mw4oxj97dY5bpOzMnjADQWxI8rN6TvTduuFLUhUMlS7/CfVZ06tcZsus6cltnNw==",
      "license": "MIT",
      "dependencies": {
-        "@csstools/css-calc": "^3.4.2",
-        "@csstools/css-color-parser": "^4.2.5",
-        "@csstools/css-parser-algorithms": "^4.0.2",
+        "@csstools/css-calc": "^3.4.1",
+        "@csstools/css-color-parser": "^4.2.4",
+        "@csstools/css-parser-algorithms": "^4.0.1",
        "@csstools/css-tokenizer": "^4.0.2",
        "lru-cache": "^11.5.3"
      },
@@ -40,9 +40,9 @@
      }
    },
    "node_modules/@asamuzakjp/dom-selector": {
-      "version": "9.2.4",
-      "resolved": "https://registry.npmjs.org/@asamuzakjp/dom-selector/-/dom-selector-9.2.4.tgz",
-      "integrity": "sha512-YnVzxDxLaqL0t7Q4wfcgHZjg55Wm6y5EaO7Bhu3q9J7wq/8iw3PhsnWiOQhYekx4VexnbkgWpTT6n+QIV7kczw==",
+      "version": "9.2.2",
+      "resolved": "https://registry.npmjs.org/@asamuzakjp/dom-selector/-/dom-selector-9.2.2.tgz",
+      "integrity": "sha512-lSWTBMjAcmu2xn5yEDU7jh6QDV+C8GEKtdJ4pIQhXh26RkKQ7S3FuQlt+zZkUbTdJ4d3XyV1kPI/G0zWXxqaqw==",
      "license": "MIT",
      "dependencies": {
        "bidi-js": "^1.1.0",
@@ -98,9 +98,9 @@
      }
    },
    "node_modules/@csstools/css-calc": {
-      "version": "3.4.3",
-      "resolved": "https://registry.npmjs.org/@csstools/css-calc/-/css-calc-3.4.3.tgz",
-      "integrity": "sha512-iex20d8CHVkyvg6B7UKV7uHnI2Bqo9g+EFfT9E0y+GvTvhZ/DwONJ+9aKb1dlqm0ZiGsL5RXjp0fCoJYnkeDjA==",
+      "version": "3.4.1",
+      "resolved": "https://registry.npmjs.org/@csstools/css-calc/-/css-calc-3.4.1.tgz",
+      "integrity": "sha512-EtC7SoN1j6J4E4DCwg5QgbO5TGxgxIA1RXqe+W+qUM+BUcezx9wT+/tiQ/WO2yCX4i5X+Cuf9ciJ22aP4UEwWw==",
      "funding": [
        {
          "type": "github",
@@ -116,14 +116,14 @@
        "node": ">=20.19.0"
      },
      "peerDependencies": {
-        "@csstools/css-parser-algorithms": "^4.0.2",
+        "@csstools/css-parser-algorithms": "^4.0.1",
        "@csstools/css-tokenizer": "^4.0.2"
      }
    },
    "node_modules/@csstools/css-color-parser": {
-      "version": "4.2.6",
-      "resolved": "https://registry.npmjs.org/@csstools/css-color-parser/-/css-color-parser-4.2.6.tgz",
-      "integrity": "sha512-iiPQ3iRWwnJkeEn6RIu6SJPr7hYrLz6XZ9s/QZl+2/LI5KQVjpl2fdmDSZKuD4xP6GMmMPgHFFXg6k1Wkz0Trg==",
+      "version": "4.2.4",
+      "resolved": "https://registry.npmjs.org/@csstools/css-color-parser/-/css-color-parser-4.2.4.tgz",
+      "integrity": "sha512-DyefytAZ735mX4Dq/WcDAXFtXhaEFvme0ZS9tVEBAc2whxUthXr0R0L2rmEPm59SrMBkGrFzQviBXMs/UtnABQ==",
      "funding": [
        {
          "type": "github",
@@ -137,20 +137,20 @@
      "license": "MIT",
      "dependencies": {
        "@csstools/color-helpers": "^6.1.2",
-        "@csstools/css-calc": "^3.4.3"
+        "@csstools/css-calc": "^3.4.1"
      },
      "engines": {
        "node": ">=20.19.0"
      },
      "peerDependencies": {
-        "@csstools/css-parser-algorithms": "^4.0.2",
+        "@csstools/css-parser-algorithms": "^4.0.1",
        "@csstools/css-tokenizer": "^4.0.2"
      }
    },
    "node_modules/@csstools/css-parser-algorithms": {
-      "version": "4.0.2",
-      "resolved": "https://registry.npmjs.org/@csstools/css-parser-algorithms/-/css-parser-algorithms-4.0.2.tgz",
-      "integrity": "sha512-40cSKyMvK+tq4qz6Awrlye2WGuOKt3FwPgtGg6KTfbHOWNw+Rk1rzbAtZnZ6IBhsY491HLRnDXwoyBAijmmILA==",
+      "version": "4.0.1",
+      "resolved": "https://registry.npmjs.org/@csstools/css-parser-algorithms/-/css-parser-algorithms-4.0.1.tgz",
+      "integrity": "sha512-ShL8BqPfbKJrJiKFH0xBbN0i7Nrh9HXYRuF+pzyj93R/BL2YAsUxJeqANErzqM+0JGl7vjHp+3OIgd/DL69YIA==",
      "funding": [
        {
          "type": "github",
@@ -170,9 +170,9 @@
      }
    },
    "node_modules/@csstools/css-syntax-patches-for-csstree": {
-      "version": "1.1.15",
-      "resolved": "https://registry.npmjs.org/@csstools/css-syntax-patches-for-csstree/-/css-syntax-patches-for-csstree-1.1.15.tgz",
-      "integrity": "sha512-J0u7HkVl2nzSlhsiTOp4AmwcUQ3D+mGEEKfBy/7To5/y7F2OHwyLrXfrhR0SMgr4p5Lo+eaMVSeai24zUcBIxA==",
+      "version": "1.1.14",
+      "resolved": "https://registry.npmjs.org/@csstools/css-syntax-patches-for-csstree/-/css-syntax-patches-for-csstree-1.1.14.tgz",
+      "integrity": "sha512-HpbVXyrofRXpHpgkNIjU/3EWR4WJvOkO3emNK/L6X/mTJU7bGUI3AkkpoTNXznQLp0KRjLHELTGeKI5dIkI9JQ==",
      "funding": [
        {
          "type": "github",
@@ -1071,16 +1071,30 @@
      }
    },
    "node_modules/data-urls": {
-      "version": "8.0.0",
-      "resolved": "https://registry.npmjs.org/data-urls/-/data-urls-8.0.0.tgz",
-      "integrity": "sha512-JQUCCK+/CAGbGGx618PlFZMXH81Jtj7t73CHv9dd/zVWvxgGT2zLFRjnKb+Ng46GIwcy+f7f88qd4duqllK+WQ==",
+      "version": "7.0.0",
+      "resolved": "https://registry.npmjs.org/data-urls/-/data-urls-7.0.0.tgz",
+      "integrity": "sha512-23XHcCF+coGYevirZceTVD7NdJOqVn+49IHyxgszm+JIiHLoB2TkmPtsYkNWT1pvRSGkc35L6NHs0yHkN2SumA==",
      "license": "MIT",
      "dependencies": {
        "whatwg-mimetype": "^5.0.0",
-        "whatwg-url": "^17.1.2"
+        "whatwg-url": "^16.0.0"
      },
      "engines": {
-        "node": "^22.14.0 || >=24.0.0"
+        "node": "^20.19.0 || ^22.12.0 || >=24.0.0"
+      }
+    },
+    "node_modules/data-urls/node_modules/whatwg-url": {
+      "version": "16.0.1",
+      "resolved": "https://registry.npmjs.org/whatwg-url/-/whatwg-url-16.0.1.tgz",
+      "integrity": "sha512-1to4zXBxmXHV3IiSSEInrreIlu02vUOvrhxJJH5vcxYTBDAx51cqZiKdyTxlecdKNSjj8EcxGBxNf6Vg+945gw==",
+      "license": "MIT",
+      "dependencies": {
+        "@exodus/bytes": "^1.11.0",
+        "tr46": "^6.0.0",
+        "webidl-conversions": "^8.0.1"
+      },
+      "engines": {
+        "node": "^20.19.0 || ^22.12.0 || >=24.0.0"
      }
    },
    "node_modules/dayjs": {
@@ -1202,30 +1216,30 @@
      "license": "MIT"
    },
    "node_modules/jsdom": {
-      "version": "30.1.2",
-      "resolved": "https://registry.npmjs.org/jsdom/-/jsdom-30.1.2.tgz",
-      "integrity": "sha512-0FFE/jE1rppmVfUrJUgxqXjcwolZYIGtAgj1pTussMhNZxIxi7W/PvfWaMNroGi2B36X1IKHbexpZ9DhkoOPiQ==",
+      "version": "30.1.1",
+      "resolved": "https://registry.npmjs.org/jsdom/-/jsdom-30.1.1.tgz",
+      "integrity": "sha512-FahmoPK5vbPc+jxV1iErMHmAZypCZ942NHF4+qqaWAuvaKKTBZxawnmAtrbGWLU7MtlxfqIP0qw6aSI+aWGtLg==",
      "license": "MIT",
      "dependencies": {
-        "@asamuzakjp/css-color": "^7.1.3",
-        "@asamuzakjp/dom-selector": "^9.2.4",
+        "@asamuzakjp/css-color": "^7.0.0",
+        "@asamuzakjp/dom-selector": "^9.2.1",
        "@bramus/specificity": "^2.4.2",
-        "@csstools/css-syntax-patches-for-csstree": "^1.1.15",
-        "@exodus/bytes": "^1.16.0",
+        "@csstools/css-syntax-patches-for-csstree": "^1.1.13",
+        "@exodus/bytes": "^1.15.1",
        "css-tree": "^3.2.1",
-        "data-urls": "^8.0.0",
+        "data-urls": "^7.0.0",
        "decimal.js": "^10.6.0",
        "html-encoding-sniffer": "^7.0.0",
        "is-potential-custom-element-name": "^1.0.1",
-        "lru-cache": "^11.5.3",
+        "lru-cache": "^11.5.2",
        "parse5": "^8.0.1",
        "saxes": "^6.0.0",
        "tough-cookie": "^6.0.2",
-        "undici": "^8.11.2",
+        "undici": "^8.10.2",
        "w3c-xmlserializer": "^6.0.0",
        "webidl-conversions": "^8.0.1",
        "whatwg-mimetype": "^5.0.0",
-        "whatwg-url": "^17.2.0",
+        "whatwg-url": "^17.1.1",
        "xml-name-validator": "^5.0.0"
      },
      "engines": {
@@ -1500,15 +1514,15 @@
      }
    },
    "node_modules/tr46": {
-      "version": "7.0.0",
-      "resolved": "https://registry.npmjs.org/tr46/-/tr46-7.0.0.tgz",
-      "integrity": "sha512-BcDSDW+SIGWVOns1Zm6Yg91q9AEj7eaID0QDY9oIqJD1A8dscNwMcl9Sms2DeuWCNov1X0/oXanHGYQBSLwZsg==",
+      "version": "6.0.0",
+      "resolved": "https://registry.npmjs.org/tr46/-/tr46-6.0.0.tgz",
+      "integrity": "sha512-bLVMLPtstlZ4iMQHpFHTR7GAGj2jxi8Dg0s2h2MafAE4uSWF98FC/3MomU51iQAMf8/qDUbKWf5GxuvvVcXEhw==",
      "license": "MIT",
      "dependencies": {
        "punycode": "^2.3.1"
      },
      "engines": {
-        "node": "^22.14.0 || >=24.0.0"
+        "node": ">=20"
      }
    },
    "node_modules/ts-dedent": {
@@ -1573,13 +1587,13 @@
      }
    },
    "node_modules/whatwg-url": {
-      "version": "17.2.0",
-      "resolved": "https://registry.npmjs.org/whatwg-url/-/whatwg-url-17.2.0.tgz",
-      "integrity": "sha512-IhLIHNcBrzIixC5XXsbr4DxdjajyA5vQ5RwGZMtrUp+GbtE5Nrsge9QKau7jXrC0aTXLYGV0xiW7Tb4YS2aomw==",
+      "version": "17.1.2",
+      "resolved": "https://registry.npmjs.org/whatwg-url/-/whatwg-url-17.1.2.tgz",
+      "integrity": "sha512-TEZA+Zqxin7Jjsm2cjRohCmen5awh+hT6Zi3VZdqZlNRk7zvOI/9WpBFg/DWlA56bWnzwm6DuB8NS0EsxQH9uQ==",
      "license": "MIT",
      "dependencies": {
-        "@exodus/bytes": "^1.16.0",
-        "tr46": "^7.0.0",
+        "@exodus/bytes": "^1.15.1",
+        "tr46": "^6.0.0",
        "webidl-conversions": "^8.0.1"
      },
      "engines": {
@@ -4,7 +4,7 @@
  "description": "Validate the Mermaid diagrams of the documentation (see check_mermaid.mjs)",
  "type": "module",
  "dependencies": {
-    "jsdom": "30.1.2",
+    "jsdom": "30.1.1",
    "mermaid": "11.17.2"
  }
 }
@@ -9,12 +9,11 @@
 #pragma once

 #include <cstdint> // uint64_t
-#include <cstring> // memcpy
-#if defined(_MSC_VER) && (defined(_M_X64) || defined(_M_ARM64)) && (!defined(__SIZEOF_INT128__) || (!defined(__GNUC__) && !defined(__clang__)))
-    #include <intrin0.h> // __umulh, _umul128, _BitScanForward64, _BitScanReverse64
+#if !defined(__SIZEOF_INT128__) && defined(_MSC_VER) && (defined(_M_X64) || defined(_M_ARM64))
+    #include <intrin0.h> // __umulh, _umul128
 #endif

-#include <nlohmann/detail/macro_scope.hpp> // JSON_HEDLEY_ALWAYS_INLINE, NLOHMANN_JSON_NAMESPACE_BEGIN
+#include <nlohmann/detail/abi_macros.hpp>

 // Portable bit-level helpers for the number and string scanners. They use
 // compiler builtins or platform-specific intrinsics where available and plain
@@ -29,10 +28,6 @@ inline int count_leading_zeros(std::uint64_t x) noexcept
 {
 #if defined(__GNUC__) || defined(__clang__)
    return __builtin_clzll(x);
-#elif defined(_MSC_VER) && (defined(_M_X64) || defined(_M_ARM64))
-    unsigned long index = 0; // NOLINT(runtime/int): the type _BitScan*64 takes
-    _BitScanReverse64(&index, x);
-    return 63 - static_cast<int>(index);
 #else
    int n = 0;
    for (int shift = 32; shift != 0; shift >>= 1)
@@ -52,10 +47,6 @@ inline int count_trailing_zeros(std::uint64_t x) noexcept
 {
 #if defined(__GNUC__) || defined(__clang__)
    return __builtin_ctzll(x);
-#elif defined(_MSC_VER) && (defined(_M_X64) || defined(_M_ARM64))
-    unsigned long index = 0; // NOLINT(runtime/int): the type _BitScan*64 takes
-    _BitScanForward64(&index, x);
-    return static_cast<int>(index);
 #else
    int n = 0;
    for (int shift = 32; shift != 0; shift >>= 1)
@@ -103,27 +94,15 @@ inline uint128_parts full_multiplication(std::uint64_t a, std::uint64_t b) noexc
 #endif
 }

-/// eight bytes as a little-endian word (a single load on little-endian
-/// targets; always inlined, as GCC otherwise calls it in the number loops)
-JSON_HEDLEY_ALWAYS_INLINE std::uint64_t read_eight_bytes(const unsigned char* b) noexcept
+/// eight bytes as a little-endian word (compilers fold this into one load on
+/// little-endian targets)
+inline std::uint64_t read_eight_bytes(const char* p) noexcept
 {
-#if defined(_MSC_VER) || defined(__x86_64__) || defined(__i386__) || (defined(__BYTE_ORDER__) && defined(__ORDER_LITTLE_ENDIAN__) && __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__)
-    // the byte order already matches (all MSVC targets are little-endian)
-    std::uint64_t result = 0;
-    std::memcpy(&result, b, sizeof(result));
-    return result;
-#else
+    const auto* b = reinterpret_cast<const unsigned char*>(p); // NOLINT(cppcoreguidelines-pro-type-reinterpret-cast)
    return static_cast<std::uint64_t>(b[0]) | (static_cast<std::uint64_t>(b[1]) << 8u)
           | (static_cast<std::uint64_t>(b[2]) << 16u) | (static_cast<std::uint64_t>(b[3]) << 24u)
           | (static_cast<std::uint64_t>(b[4]) << 32u) | (static_cast<std::uint64_t>(b[5]) << 40u)
           | (static_cast<std::uint64_t>(b[6]) << 48u) | (static_cast<std::uint64_t>(b[7]) << 56u);
-#endif
-}
-
-/// eight bytes as a little-endian word
-JSON_HEDLEY_ALWAYS_INLINE std::uint64_t read_eight_bytes(const char* p) noexcept
-{
-    return read_eight_bytes(reinterpret_cast<const unsigned char*>(p)); // NOLINT(cppcoreguidelines-pro-type-reinterpret-cast)
 }

 }  // namespace detail
@@ -4,7 +4,6 @@
 // |_____|_____|_____|_|___|  https://github.com/nlohmann/json
 //
 // SPDX-FileCopyrightText: 2009 Florian Loitsch <https://florian.loitsch.com/>
-// SPDX-FileCopyrightText: 2025 Victor Zverovich <https://github.com/vitaut/zmij>
 // SPDX-FileCopyrightText: 2013-2026 Niels Lohmann <https://nlohmann.me>
 // SPDX-License-Identifier: MIT

@@ -12,32 +11,11 @@

 #include <array> // array
 #include <cmath>   // signbit, isfinite
-#include <cstddef> // size_t
 #include <cstdint> // intN_t, uintN_t
 #include <cstring> // memcpy, memmove
 #include <limits> // numeric_limits
 #include <type_traits> // conditional

-#ifdef _MSC_VER
-    #include <cstdlib> // _byteswap_uint64
-#endif
-
-// SSE2 (every x86-64 CPU) and NEON (every 64-bit Arm CPU) convert the 16
-// digits of a double at once
-#if defined(__x86_64__) || (defined(_M_X64) && !defined(_M_ARM64EC))
-    #include <emmintrin.h>
-    #define JSON_DTOA_SSE2 1
-    #define JSON_DTOA_NEON 0
-#elif (defined(__aarch64__) || defined(_M_ARM64)) && !defined(_M_ARM64EC) && !defined(__ARM_BIG_ENDIAN)
-    #include <arm_neon.h>
-    #define JSON_DTOA_SSE2 0
-    #define JSON_DTOA_NEON 1
-#else
-    #define JSON_DTOA_SSE2 0
-    #define JSON_DTOA_NEON 0
-#endif
-
-#include <nlohmann/detail/conversions/zmij.hpp>
 #include <nlohmann/detail/macro_scope.hpp>

 NLOHMANN_JSON_NAMESPACE_BEGIN
@@ -1069,381 +1047,6 @@ inline char* format_buffer(char* buf, int len, int decimal_exponent,
    return append_exponent(buf, n - 1);
 }

-/// eight decimal digits (a value below 10^8) as bytes 0..9, the first digit
-/// in the most significant byte: three steps that divide all lanes at once
-/// by a multiplication (the conversion of Xiang JunBo, as in Zmij)
-inline std::uint64_t eight_digit_bytes(std::uint64_t abcdefgh) noexcept
-{
-    const std::uint64_t abcd_efgh = abcdefgh + (((std::uint64_t{1} << 32u) - 10000u) * ((abcdefgh * (((std::uint64_t{1} << 40u) / 10000u) + 1u)) >> 40u));
-    const std::uint64_t ab_cd_ef_gh = abcd_efgh + (((std::uint64_t{1} << 16u) - 100u) * (((abcd_efgh * (((std::uint64_t{1} << 19u) / 100u) + 1u)) >> 19u) & 0x7F0000007Fu));
-    return ab_cd_ef_gh + (((std::uint64_t{1} << 8u) - 10u) * (((ab_cd_ef_gh * (((std::uint64_t{1} << 10u) / 10u) + 1u)) >> 10u) & 0x000F000F000F000Fu));
-}
-
-/// store the bytes of v, the most significant one first (one byte swap and
-/// one store where the byte order is known: compilers do not reliably merge
-/// the byte stores once this is inlined)
-inline void store_msb_first(char* p, std::uint64_t v) noexcept
-{
-#if defined(__BYTE_ORDER__) && defined(__ORDER_LITTLE_ENDIAN__) && __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
-    v = __builtin_bswap64(v);
-    std::memcpy(p, &v, sizeof(v));
-#elif defined(__BYTE_ORDER__) && defined(__ORDER_BIG_ENDIAN__) && __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
-    std::memcpy(p, &v, sizeof(v));
-#elif defined(_MSC_VER) // (little-endian on all its targets)
-    v = _byteswap_uint64(v);
-    std::memcpy(p, &v, sizeof(v));
-#else
-    for (unsigned i = 0; i < 8; ++i)
-    {
-        p[i] = static_cast<char>(v >> (56u - (8u * i)));
-    }
-#endif
-}
-
-/*!
-@brief digits * 10^exp for a double, in the layout of format_buffer()
-
-The layout is that of format_buffer() with min_exp -4 and max_exp 15 (the
-digits10 of double). The digits are converted eight at a time and placed
-with fixed-size moves instead of per-digit loops and moves of the buffer.
-
-@param[in] digits  the digits (not 0, at most 17 digits; trailing zeros allowed)
-@param[in] exp     the decimal exponent of the last digit
-@return a pointer past the text; up to 41 bytes at @a first are written
-        (some beyond the returned end)
-*/
-JSON_HEDLEY_NON_NULL(1)
-JSON_HEDLEY_RETURNS_NON_NULL
-inline char* write_decimal(char* first, std::uint64_t digits, int exp) noexcept
-{
-    JSON_ASSERT(digits != 0 && digits < 100000000000000000u);
-    const std::uint64_t upper = digits / 100000000u;
-    const std::uint64_t b0 = upper / 100000000u; // (one digit: it is its own byte)
-    const std::uint64_t b1 = eight_digit_bytes(upper % 100000000u);
-    const std::uint64_t b2 = eight_digit_bytes(digits % 100000000u);
-    // leading and trailing zero digits: zero bytes, counted without division
-    int leading = 16;
-    int zeros = 16;
-    if (b0 != 0)
-    {
-        leading = count_leading_zeros(b0) / 8;
-    }
-    else if (b1 != 0)
-    {
-        leading = 8 + (count_leading_zeros(b1) / 8);
-    }
-    else
-    {
-        leading += count_leading_zeros(b2) / 8;
-    }
-    if (b2 != 0)
-    {
-        zeros = count_trailing_zeros(b2) / 8;
-    }
-    else if (b1 != 0)
-    {
-        zeros = 8 + (count_trailing_zeros(b1) / 8);
-    }
-    // (else: 16, b0 is the one digit that is not 0)
-    // the digits as text at text + leading, then '0's, so that fixed-size
-    // moves need not check how many digits there are
-    std::array<char, 64> text; // NOLINT(cppcoreguidelines-pro-type-member-init,hicpp-member-init): written before read
-    store_msb_first(text.data(), b0 + 0x3030303030303030u);
-    store_msb_first(text.data() + 8, b1 + 0x3030303030303030u);
-    store_msb_first(text.data() + 16, b2 + 0x3030303030303030u);
-    std::memset(text.data() + 24, '0', 40);
-    const int k = 24 - leading - zeros; // significant digits
-    const int n = k + exp + zeros;      // position of the decimal point after the first digit
-    const char* const s0 = text.data() + leading;
-
-    if (-4 < n && n <= 15)
-    {
-        // "0.[000]digits" (n <= 0) is the digits after 1 - n leading '0's
-        // with the point after the first; "digits[000].0" (n >= k) and
-        // "dig.its" put the point after n characters
-        const int pad = n <= 0 ? 1 - n : 0;
-        const char* const s = s0 - pad;
-        const int len = k + pad;
-        const int point = n + pad;
-        std::memcpy(first, s, 16);
-        std::memcpy(first + point + 1, s + point, 24);
-        first[point] = '.';
-        return first + (point >= len ? point + 2 : len + 1);
-    }
-
-    // d.igitse+XX, with at least two exponent digits (as append_exponent())
-    std::memcpy(first, s0, 16);
-    std::memcpy(first + 2, s0 + 1, 16);
-    first[1] = '.';
-    char* const end = first + (k == 1 ? 1 : k + 1);
-    const int e = n - 1;
-    const auto ea = e < 0 ? 0u - static_cast<unsigned>(e) : static_cast<unsigned>(e); // (unsigned: no signed overflow to assume)
-    const bool three = ea >= 100;
-    end[0] = 'e';
-    end[1] = e < 0 ? '-' : '+';
-    end[2] = static_cast<char>('0' + (three ? ea / 100 : (ea / 10) % 10));
-    end[3] = static_cast<char>('0' + (three ? (ea / 10) % 10 : ea % 10));
-    end[4] = static_cast<char>('0' + (ea % 10));
-    return end + (three ? 5 : 4);
-}
-
-/*!
-@brief the shortest decimal of a positive double (Zmij), as write_decimal()
-writes it
-
-For a normal double, the shorter candidate has 15 or 16 digits: they are
-converted at once (two halves of eight digits) and followed by the digit
-after them, if there is one, without the multiplication and division by 10
-that counting the digits of one number would take. The fixed layouts move
-the digits after the point by one byte.
-
-@return a pointer past the text; up to 41 bytes at @a first are written
-        (some beyond the returned end)
-*/
-JSON_HEDLEY_NON_NULL(1)
-JSON_HEDLEY_RETURNS_NON_NULL
-inline char* write_shortest(char* first, const zmij::shortest_decimal d) noexcept
-{
-    const std::uint64_t sig = d.integral;
-    if (JSON_HEDLEY_UNLIKELY(sig < 100000000000000u || sig >= 10000000000000000u))
-    {
-        // (subnormals)
-        return d.has_digit ? write_decimal(first, (sig * 10) + d.digit, d.exponent) : write_decimal(first, sig, d.exponent + 1);
-    }
-    const bool sixteen = sig >= 1000000000000000u; // (else 15 digits)
-    const int last = d.has_digit ? d.digit : 0;
-    const std::uint64_t upper = sig / 100000000u;
-#if JSON_DTOA_SSE2
-    // NOLINTBEGIN(portability-simd-intrinsics)
-    // the two halves in the 64-bit lanes, each as abcd * 2^32 + efgh, then as
-    // bytes (as eight_digit_bytes(), one lane each)
-    const __m128i x = _mm_set_epi64x(static_cast<long long>(sig - (upper * 100000000u)), static_cast<long long>(upper)); // NOLINT(runtime/int)
-    const __m128i abcd = _mm_srli_epi64(_mm_mul_epu32(x, _mm_set1_epi64x(109951163)), 40); // 2^40 / 10000 + 1
-    const __m128i abcd_efgh = _mm_add_epi64(x, _mm_mul_epu32(abcd, _mm_set1_epi64x(4294957296))); // 2^32 - 10000
-    // 32-bit lanes in the order of the text: abcd, efgh of both halves
-    const __m128i fours = _mm_shuffle_epi32(abcd_efgh, _MM_SHUFFLE(2, 3, 0, 1));
-    const __m128i ab = _mm_srli_epi16(_mm_mulhi_epu16(fours, _mm_set1_epi32(5243)), 3);
-    const __m128i ab_cd = _mm_or_si128(_mm_slli_epi32(_mm_sub_epi16(fours, _mm_mullo_epi16(ab, _mm_set1_epi32(100))), 16), ab);
-    // 16-bit lanes ab (< 100) -> bytes a, b: 256 * ab - 2559 * (ab / 10)
-    const __m128i bytes = _mm_sub_epi16(_mm_slli_epi16(ab_cd, 8), _mm_mullo_epi16(_mm_set1_epi16(2559), _mm_mulhi_epu16(ab_cd, _mm_set1_epi16(6554))));
-    // the last digit that is not 0 (sig is not 0)
-    const auto nonzero = static_cast<std::uint64_t>(_mm_movemask_epi8(_mm_cmpgt_epi8(bytes, _mm_setzero_si128())));
-    const int digits = 63 - count_leading_zeros(nonzero) + (sixteen ? 1 : 0); // without trailing zeros
-    const __m128i chars = _mm_add_epi8(bytes, _mm_set1_epi8('0'));
-    // the 16 characters from the first digit
-    const __m128i s = sixteen ? chars : _mm_or_si128(_mm_srli_si128(chars, 1), _mm_slli_si128(_mm_cvtsi32_si128('0' + last), 15));
-    const char s16 = static_cast<char>(sixteen ? '0' + last : '0'); // the 17th
-    const auto store_16 = [&s](char* p) noexcept
-    {
-        std::memcpy(p, &s, 16);
-    };
-    const char first_digit = static_cast<char>(_mm_cvtsi128_si32(s));
-    // NOLINTEND(portability-simd-intrinsics)
-#elif JSON_DTOA_NEON
-    // as with SSE2: the halves in 32-bit lanes, then abcd, efgh of both
-    const uint32x2_t halves = vcreate_u32(upper | ((sig - (upper * 100000000u)) << 32u));
-    const uint32x2_t abcd = vmovn_u64(vshrq_n_u64(vmull_n_u32(halves, static_cast<std::uint32_t>(((std::uint64_t{1} << 40u) / 10000u) + 1u)), 40));
-    const uint32x2_t efgh = vmls_n_u32(halves, abcd, 10000u);
-    const uint32x4_t fours = vcombine_u32(vzip1_u32(abcd, efgh), vzip2_u32(abcd, efgh));
-    const uint32x4_t ab = vshrq_n_u32(vmulq_n_u32(fours, 5243u), 19);
-    const uint16x8_t ab_cd = vreinterpretq_u16_u32(vorrq_u32(ab, vshlq_n_u32(vmlsq_n_u32(fours, ab, 100u), 16)));
-    const uint16x8_t tens = vshrq_n_u16(vmulq_n_u16(ab_cd, 103u), 10);
-    const uint8x16_t bytes = vreinterpretq_u8_u16(vorrq_u16(tens, vshlq_n_u16(vmlsq_n_u16(ab_cd, tens, 10u), 8)));
-    // the last digit that is not 0 (sig is not 0): a nibble per byte
-    const std::uint64_t nonzero = vget_lane_u64(vreinterpret_u64_u8(vshrn_n_u16(vreinterpretq_u16_u8(vtstq_u8(bytes, bytes)), 4)), 0);
-    const int digits = ((63 - count_leading_zeros(nonzero)) / 4) + (sixteen ? 1 : 0); // without trailing zeros
-    const uint8x16_t chars = vaddq_u8(bytes, vdupq_n_u8('0'));
-    // the 16 characters from the first digit
-    const uint8x16_t s = sixteen ? chars : vextq_u8(chars, vdupq_n_u8(static_cast<std::uint8_t>('0' + last)), 1);
-    const char s16 = static_cast<char>(sixteen ? '0' + last : '0'); // the 17th
-    const auto store_16 = [&s](char* p) noexcept
-    {
-        vst1q_u8(reinterpret_cast<std::uint8_t*>(p), s); // NOLINT(cppcoreguidelines-pro-type-reinterpret-cast)
-    };
-    const auto first_digit = static_cast<char>(vgetq_lane_u8(s, 0));
-#else
-    const std::uint64_t hi = eight_digit_bytes(upper);
-    const std::uint64_t lo = eight_digit_bytes(sig - (upper * 100000000u));
-    // trailing zero digits: zero bytes (sig is not 0)
-    const int zeros = lo != 0 ? count_trailing_zeros(lo) / 8 : 8 + (count_trailing_zeros(hi) / 8);
-    const int digits = 15 - zeros + (sixteen ? 1 : 0); // without trailing zeros
-    // the 16 characters from the first digit
-    const std::uint64_t s_hi = (sixteen ? hi : (hi << 8u) | (lo >> 56u)) + 0x3030303030303030u;
-    const std::uint64_t s_lo = (sixteen ? lo : (lo << 8u) | static_cast<std::uint64_t>(last)) + 0x3030303030303030u;
-    const char s16 = static_cast<char>(sixteen ? '0' + last : '0'); // the 17th
-    const auto store_16 = [s_hi, s_lo](char* p) noexcept
-    {
-        store_msb_first(p, s_hi);
-        store_msb_first(p + 8, s_lo);
-    };
-    const auto first_digit = static_cast<char>(s_hi >> 56u);
-#endif
-    const int len = d.has_digit ? 16 + (sixteen ? 1 : 0) : digits; // significant digits
-    const int n = 16 + (sixteen ? 1 : 0) + d.exponent;           // digits before the point
-
-    if (JSON_HEDLEY_LIKELY(n >= 1 && n <= 15))
-    {
-        // "dig.its" and "digits[000].0": the digits after the point move by
-        // one byte ('0's follow the digits)
-#if JSON_DTOA_SSE2
-        // NOLINTBEGIN(portability-simd-intrinsics)
-        // (in the register: reading the digits back from memory right after
-        // storing them waits until the stores are done)
-        const __m128i at = _mm_set1_epi8(static_cast<char>(n));
-        const __m128i index = _mm_setr_epi8(0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15);
-        const __m128i before = _mm_cmpgt_epi8(at, index);
-        const __m128i after = _mm_cmpgt_epi8(index, at);
-        const __m128i text = _mm_or_si128(_mm_or_si128(_mm_and_si128(s, before), _mm_and_si128(_mm_slli_si128(s, 1), after)),
-                                          _mm_andnot_si128(_mm_or_si128(before, after), _mm_set1_epi8('.')));
-        std::memcpy(first, &text, 16);
-        first[16] = static_cast<char>(_mm_extract_epi16(s, 7) >> 8);
-        first[17] = s16;
-        // NOLINTEND(portability-simd-intrinsics)
-#elif JSON_DTOA_NEON
-        const uint8x16_t index = vcombine_u8(vcreate_u8(0x0706050403020100u), vcreate_u8(0x0F0E0D0C0B0A0908u));
-        const uint8x16_t at = vdupq_n_u8(static_cast<std::uint8_t>(n));
-        const uint8x16_t after_point = vbslq_u8(vcgtq_u8(index, at), vextq_u8(vdupq_n_u8(0), s, 15), vdupq_n_u8('.'));
-        vst1q_u8(reinterpret_cast<std::uint8_t*>(first), vbslq_u8(vcltq_u8(index, at), s, after_point)); // NOLINT(cppcoreguidelines-pro-type-reinterpret-cast)
-        first[16] = static_cast<char>(vgetq_lane_u8(s, 15));
-        first[17] = s16;
-#else
-        store_16(first);
-        first[16] = s16;
-        std::uint64_t after_point[2]; // NOLINT(cppcoreguidelines-avoid-c-arrays,hicpp-avoid-c-arrays,modernize-avoid-c-arrays,cppcoreguidelines-pro-type-member-init,hicpp-member-init): written before read
-        std::memcpy(after_point, first + n, 16);
-        std::memcpy(first + n + 1, after_point, 16);
-        first[n] = '.';
-#endif
-        return first + (n >= len ? n + 2 : len + 1);
-    }
-    if (n <= 0 && n > -4)
-    {
-        // "0.[000]digits"
-        std::memset(first, '0', 8);
-        first[1] = '.';
-        store_16(first + 2 - n);
-        first[18 - n] = s16;
-        return first + 2 - n + len;
-    }
-    // d.igitse+XX, with at least two exponent digits (as append_exponent())
-    store_16(first + 1);
-    first[17] = s16;
-    first[0] = first_digit;
-    first[1] = '.';
-    char* const end = first + (len == 1 ? 1 : len + 1);
-    const int e = n - 1;
-    const auto ea = e < 0 ? 0u - static_cast<unsigned>(e) : static_cast<unsigned>(e); // (unsigned: no signed overflow to assume)
-    const bool three = ea >= 100;
-    end[0] = 'e';
-    end[1] = e < 0 ? '-' : '+';
-    end[2] = static_cast<char>('0' + (three ? ea / 100 : (ea / 10) % 10));
-    end[3] = static_cast<char>('0' + (three ? (ea / 10) % 10 : ea % 10));
-    end[4] = static_cast<char>('0' + (ea % 10));
-    return end + (three ? 5 : 4);
-}
-
-/*!
-@brief whether FloatType is an IEEE 754 binary64 type (a double, or a long double
-that has the same format, as with MSVC and on Apple's Arm CPUs)
-
-These are the types the conversion of Zmij (see zmij.hpp) is used for; all
-others (binary32, or a format the library does not know) use Grisu2.
-*/
-template<typename FloatType>
-constexpr bool has_binary64_format() noexcept
-{
-    return std::numeric_limits<FloatType>::is_iec559
-           && std::numeric_limits<FloatType>::digits == 53
-           && std::numeric_limits<FloatType>::max_exponent == 1024
-           && sizeof(FloatType) == sizeof(std::uint64_t);
-}
-
-template<typename FloatType>
-struct is_binary64 : std::integral_constant<bool, has_binary64_format<FloatType>()> {};
-
-/// a positive finite float (other than binary64): Grisu2 and format_buffer()
-template<typename FloatType>
-JSON_HEDLEY_NON_NULL(1, 2)
-JSON_HEDLEY_RETURNS_NON_NULL
-char* write_positive_grisu2(char* first, const char* last, FloatType value)
-{
-    JSON_ASSERT(last - first >= std::numeric_limits<FloatType>::max_digits10);
-    static_cast<void>(last); // (only used in the assertion)
-
-    // Compute v = buffer * 10^decimal_exponent.
-    // The decimal digits are stored in the buffer, which needs to be interpreted
-    // as an unsigned decimal integer.
-    // len is the length of the buffer, i.e., the number of decimal digits.
-    int len = 0;
-    int decimal_exponent = 0;
-    grisu2(first, len, decimal_exponent, value);
-
-    JSON_ASSERT(len <= std::numeric_limits<FloatType>::max_digits10);
-
-    // Format the buffer like printf("%.*g", prec, value)
-    constexpr int kMinExp = -4;
-    // Use digits10 here to increase compatibility with version 2.
-    constexpr int kMaxExp = std::numeric_limits<FloatType>::digits10;
-
-    JSON_ASSERT(last - first >= kMaxExp + 2);
-    JSON_ASSERT(last - first >= 2 + (-kMinExp - 1) + std::numeric_limits<FloatType>::max_digits10);
-    JSON_ASSERT(last - first >= std::numeric_limits<FloatType>::max_digits10 + 6);
-
-    return format_buffer(first, len, decimal_exponent, kMinExp, kMaxExp);
-}
-
-/// a positive finite binary64 number: the shortest digits (Zmij), laid out by
-/// write_shortest() (through a local buffer if [first, last) is shorter than
-/// the 41 bytes it may write)
-template<typename FloatType>
-JSON_HEDLEY_NON_NULL(1, 2)
-JSON_HEDLEY_RETURNS_NON_NULL
-char* write_positive_zmij(char* first, const char* last, FloatType value)
-{
-    static_assert(is_binary64<FloatType>::value,
-                  "internal error: the conversion of Zmij needs IEEE 754 binary64 numbers");
-    std::uint64_t bits = 0;
-    std::memcpy(&bits, &value, sizeof(bits));
-    const zmij::shortest_decimal d = zmij::to_shortest(bits);
-    if (JSON_HEDLEY_LIKELY(last - first >= 41))
-    {
-        return write_shortest(first, d);
-    }
-    std::array<char, 64> buf; // NOLINT(cppcoreguidelines-pro-type-member-init,hicpp-member-init): written before read
-    const auto len = static_cast<std::size_t>(write_shortest(buf.data(), d) - buf.data());
-    JSON_ASSERT(last - first >= static_cast<std::ptrdiff_t>(len));
-    std::memcpy(first, buf.data(), len);
-    return first + len;
-}
-
-/// a positive finite binary64 number: Zmij (as a long double has the format of
-/// a double here, its bits are those of the double of the same value)
-template<typename FloatType>
-JSON_HEDLEY_NON_NULL(1, 2)
-JSON_HEDLEY_RETURNS_NON_NULL
-char* write_positive(char* first, const char* last, FloatType value, std::true_type /*is_binary64*/)
-{
-    return write_positive_zmij(first, last, value);
-}
-
-/// a positive finite float of any other format: Grisu2
-template<typename FloatType>
-JSON_HEDLEY_NON_NULL(1, 2)
-JSON_HEDLEY_RETURNS_NON_NULL
-char* write_positive(char* first, const char* last, FloatType value, std::false_type /*is_binary64*/)
-{
-    return write_positive_grisu2(first, last, value);
-}
-
-/// a positive finite float: Zmij for binary64 numbers, Grisu2 otherwise
-template<typename FloatType>
-JSON_HEDLEY_NON_NULL(1, 2)
-JSON_HEDLEY_RETURNS_NON_NULL
-char* write_positive(char* first, const char* last, FloatType value)
-{
-    return write_positive(first, last, value, is_binary64<FloatType> {});
-}
-
 }  // namespace dtoa_impl

 /*!
@@ -1461,6 +1064,7 @@ JSON_HEDLEY_NON_NULL(1, 2)
 JSON_HEDLEY_RETURNS_NON_NULL
 char* to_chars(char* first, const char* last, FloatType value)
 {
+    static_cast<void>(last); // maybe unused - fix warning
    JSON_ASSERT(std::isfinite(value));

    // Use signbit(value) instead of (value < 0) since signbit works for -0.
@@ -1486,7 +1090,28 @@ char* to_chars(char* first, const char* last, FloatType value)
    JSON_HEDLEY_DIAGNOSTIC_POP
 #endif

-    return dtoa_impl::write_positive(first, last, value);
+    JSON_ASSERT(last - first >= std::numeric_limits<FloatType>::max_digits10);
+
+    // Compute v = buffer * 10^decimal_exponent.
+    // The decimal digits are stored in the buffer, which needs to be interpreted
+    // as an unsigned decimal integer.
+    // len is the length of the buffer, i.e., the number of decimal digits.
+    int len = 0;
+    int decimal_exponent = 0;
+    dtoa_impl::grisu2(first, len, decimal_exponent, value);
+
+    JSON_ASSERT(len <= std::numeric_limits<FloatType>::max_digits10);
+
+    // Format the buffer like printf("%.*g", prec, value)
+    constexpr int kMinExp = -4;
+    // Use digits10 here to increase compatibility with version 2.
+    constexpr int kMaxExp = std::numeric_limits<FloatType>::digits10;
+
+    JSON_ASSERT(last - first >= kMaxExp + 2);
+    JSON_ASSERT(last - first >= 2 + (-kMinExp - 1) + std::numeric_limits<FloatType>::max_digits10);
+    JSON_ASSERT(last - first >= std::numeric_limits<FloatType>::max_digits10 + 6);
+
+    return dtoa_impl::format_buffer(first, len, decimal_exponent, kMinExp, kMaxExp);
 }

 }  // namespace detail
@@ -1,219 +0,0 @@
-//     __ _____ _____ _____
-//  __|  |   __|     |   | |  JSON for Modern C++
-// |  |  |__   |  |  | | | |  version 3.12.0
-// |_____|_____|_____|_|___|  https://github.com/nlohmann/json
-//
-// SPDX-FileCopyrightText: 2025 Victor Zverovich <https://github.com/vitaut/zmij>
-// SPDX-FileCopyrightText: 2013-2026 Niels Lohmann <https://nlohmann.me>
-// SPDX-License-Identifier: MIT
-
-#pragma once
-
-#include <array> // array
-#include <cstddef> // size_t
-#include <cstdint> // uint32_t, uint64_t
-
-#include <nlohmann/detail/abi_macros.hpp>
-#include <nlohmann/detail/bit_ops.hpp>
-#include <nlohmann/detail/input/pow5_table.hpp>
-#include <nlohmann/detail/macro_scope.hpp>
-
-NLOHMANN_JSON_NAMESPACE_BEGIN
-namespace detail
-{
-
-/*!
-@brief the shortest decimal representation of a double
-
-A C++11 port of the conversion of Zmij by Victor Zverovich
-(https://github.com/vitaut/zmij, MIT license): the shortest decimal in the
-rounding interval of a double, the closest one if there are several. Zmij
-credits Xiang JunBo (producing the shorter candidate without a division) and
-Dougall Johnson (the compressed powers of ten). The powers of ten are taken
-from the table for number parsing (pow5_table.hpp) where it holds them, and
-computed from the compressed tables of Zmij beyond it.
-*/
-namespace zmij
-{
-
-/// the compressed powers of ten of Zmij
-inline const std::array<std::uint64_t, 28>& pow10_minor() noexcept
-{
-    static const std::array<std::uint64_t, 28> table =
-    {
-        {
-            0x8000000000000000u, 0xa000000000000000u, 0xc800000000000000u, 0xfa00000000000000u, 0x9c40000000000000u,
-            0xc350000000000000u, 0xf424000000000000u, 0x9896800000000000u, 0xbebc200000000000u, 0xee6b280000000000u,
-            0x9502f90000000000u, 0xba43b74000000000u, 0xe8d4a51000000000u, 0x9184e72a00000000u, 0xb5e620f480000000u,
-            0xe35fa931a0000000u, 0x8e1bc9bf04000000u, 0xb1a2bc2ec5000000u, 0xde0b6b3a76400000u, 0x8ac7230489e80000u,
-            0xad78ebc5ac620000u, 0xd8d726b7177a8000u, 0x878678326eac9000u, 0xa968163f0a57b400u, 0xd3c21bcecceda100u,
-            0x84595161401484a0u, 0xa56fa5b99019a5c8u, 0xcecb8f27f4200f3au
-        }
-    };
-    return table;
-}
-
-/// (high, low) pairs
-inline const std::array<std::uint64_t, 50>& pow10_major() noexcept
-{
-    static const std::array<std::uint64_t, 50> table =
-    {
-        {
-            0xaddcb9e83c6b1793u, 0xdf4abe242a1bbf3eu, 0xaf8e5410288e1b6fu, 0x07ecf0ae5ee44ddau, 0xb1442798f49ffb4au, 0x99cd11cfdf41779du,
-            0xb2fe3f0b8599ef07u, 0x861fa7e6dcb4aa15u, 0xb4bca50b065abe63u, 0x0fed077a756b53aau, 0xb67f6455292cbf08u, 0x1a3bc84c17b1d543u,
-            0xb84687c269ef3bfbu, 0x3d5d514f40eea742u, 0xba121a4650e4ddebu, 0x92f34d62616ce413u, 0xbbe226efb628afeau, 0x890489f70a55368cu,
-            0xbdb6b8e905cb600fu, 0x5400e987bbc1c921u, 0xbf8fdb78849a5f96u, 0xde98520472bdd034u, 0xc16d9a0095928a27u, 0x75b7053c0f178294u,
-            0xc350000000000000u, 0x0000000000000000u, 0xc5371912364ce305u, 0x6c28000000000000u, 0xc722f0ef9d80aad6u, 0x424d3ad2b7b97ef6u,
-            0xc913936dd571c84cu, 0x03bc3a19cd1e38eau, 0xcb090c8001ab551cu, 0x5cadf5bfd3072cc6u, 0xcd036837130890a1u, 0x36dba887c37a8c10u,
-            0xcf02b2c21207ef2eu, 0x94f967e45e03f4bcu, 0xd106f86e69d785c7u, 0xe13336d701beba52u, 0xd31045a8341ca07cu, 0x1ede48111209a051u,
-            0xd51ea6fa85785631u, 0x552a74227f3ea566u, 0xd732290fbacaf133u, 0xa97c177947ad4096u, 0xd94ad8b1c7380874u, 0x18375281ae7822bdu,
-            0xdb68c2ca82ed2a05u, 0xa67398db9f6820e1u
-        }
-    };
-    return table;
-}
-
-/// one bit per power: whether the computed value is one unit too large
-inline const std::array<std::uint32_t, 21>& pow10_fixups() noexcept
-{
-    static const std::array<std::uint32_t, 21> table =
-    {
-        {
-            0x8d8fc810u, 0x06100293u, 0x19000000u, 0x00100000u, 0x00000908u, 0x00000000u, 0x04e00300u, 0x3807e0b2u, 0x3d83d793u, 0x0006f5ccu,
-            0x00000000u, 0xffff0000u, 0x8076337du, 0x4ff45ba0u, 0x09405033u, 0x034376d9u, 0x09000000u, 0x4e100501u, 0x076d14dcu, 0xf964f45eu,
-            0x0000003du
-        }
-    };
-    return table;
-}
-
-/// the 128-bit significand of 10^k, rounded down, for k in [-307, 341]
-/// (compute_pow10 of Zmij)
-inline uint128_parts compute_pow10(int k) noexcept
-{
-    const auto i = static_cast<unsigned>(k + 307);
-    const std::uint64_t m = pow10_minor()[(i + 24) % 28];
-    const std::size_t j = 2 * static_cast<std::size_t>((i + 24) / 28);
-    const std::uint64_t h_hi = pow10_major()[j];
-    const std::uint64_t h_lo = pow10_major()[j + 1];
-    const std::uint64_t h1 = full_multiplication(h_lo, m).high;
-    const std::uint64_t c0 = h_lo * m;
-    const std::uint64_t c1 = h1 + (h_hi * m);
-    const std::uint64_t c2 = (c1 < h1 ? 1u : 0u) + full_multiplication(h_hi, m).high;
-    uint128_parts r{};
-    if ((c2 >> 63u) != 0)
-    {
-        r.high = c2;
-        r.low = c1;
-    }
-    else
-    {
-        r.high = (c2 << 1u) | (c1 >> 63u);
-        r.low = (c1 << 1u) | (c0 >> 63u);
-    }
-    r.low -= (pow10_fixups()[i >> 5u] >> (i & 31u)) & 1u;
-    return r;
-}
-
-/// The 128-bit significand of 10^k, rounded down, for k in [-342, 341].
-/// Up to 10^308, the table for number parsing holds the same significands
-/// (those of 5^k), except for k in [-27, -1], where it holds them one unit
-/// larger (as the Eisel-Lemire algorithm needs them).
-inline uint128_parts pow10(int k) noexcept
-{
-    if (k > pow5_128_largest_power)
-    {
-        return compute_pow10(k); // (only for the smallest doubles)
-    }
-    const auto i = 2 * static_cast<std::size_t>(k - pow5_128_smallest_power);
-    uint128_parts r{pow5_128()[i + 1], pow5_128()[i]};
-    const std::uint64_t adjust = static_cast<unsigned>(k + 27) < 27u ? 1u : 0u;
-    r.high -= r.low < adjust ? 1u : 0u;
-    r.low -= adjust;
-    return r;
-}
-
-/// (x_hi * 2^64 + x_lo) * y >> 64, as 128 bits
-inline uint128_parts umul192_hi128(std::uint64_t x_hi, std::uint64_t x_lo, std::uint64_t y) noexcept
-{
-    const uint128_parts p = full_multiplication(x_hi, y);
-    uint128_parts r{};
-    r.low = p.low + full_multiplication(x_lo, y).high;
-    r.high = p.high + (r.low < p.low ? 1u : 0u);
-    return r;
-}
-
-/// (x * y + c) >> 64
-inline std::uint64_t umul128_add_hi64(std::uint64_t x, std::uint64_t y, std::uint64_t c) noexcept
-{
-    const uint128_parts p = full_multiplication(x, y);
-    return p.high + (p.low + c < p.low ? 1u : 0u);
-}
-
-/// the result of Zmij: the shorter candidate and, if that is outside the
-/// rounding interval, the digit after it (16 bytes: returned in registers)
-struct shortest_decimal
-{
-    std::uint64_t integral;  ///< the shorter candidate (15 or 16 digits for normal doubles)
-    int exponent;            ///< the decimal exponent of the digit after it
-    unsigned char digit;     ///< the digit after it (if has_digit)
-    bool has_digit;          ///< whether the shortest decimal is integral * 10 + digit
-};
-
-/// The shortest decimal in the rounding interval of a positive finite double
-/// given by its bits, the closest one if there are several (to_decimal of
-/// Zmij, which keeps the last digit apart: the 15 or 16 digits before it can be
-/// converted without a multiplication by 10 first). Always inlined: GCC
-/// otherwise calls it, and its result goes through memory.
-JSON_HEDLEY_ALWAYS_INLINE shortest_decimal to_shortest(std::uint64_t bits) noexcept
-{
-    constexpr int extra_shift = 9;
-    const auto raw_exp = static_cast<int>((bits >> 52u) & 0x7FFu);
-    std::uint64_t bin_sig = bits & ((std::uint64_t{1} << 52u) - 1);
-    // a power of two has a narrower interval below (except the smallest normal)
-    const bool regular = bin_sig != 0 || raw_exp <= 1;
-    const int bin_exp = (raw_exp == 0 ? 1 : raw_exp) - 1075;
-    if (raw_exp != 0)
-    {
-        bin_sig |= std::uint64_t{1} << 52u;
-    }
-    // floor(log10(2^bin_exp)), or floor(log10(3/4 * 2^bin_exp)) for the irregular case
-    const int dec_exp = ((bin_exp * 315653) - (regular ? 0 : 131072)) >> 20;
-    // scaled by 10^(-dec_exp - 1): the integral part is the shorter candidate
-    const int shift = bin_exp + ((-(dec_exp + 1) * 217707) >> 16) + 1 + extra_shift;
-    const uint128_parts p10 = pow10(-dec_exp - 1);
-    const uint128_parts p = umul192_hi128(p10.high, p10.low, bin_sig << static_cast<unsigned>(shift));
-    std::uint64_t integral = p.high >> static_cast<unsigned>(extra_shift);
-    const std::uint64_t fractional = (p.high << static_cast<unsigned>(64 - extra_shift)) | (p.low >> static_cast<unsigned>(extra_shift));
-    std::uint64_t digit = 0;
-    bool round_up = false;
-    bool round_down = false;
-    if (JSON_HEDLEY_LIKELY(regular))
-    {
-        const std::uint64_t half_ulp = (p10.high >> static_cast<unsigned>(extra_shift + 1 - shift)) + (1 - (bin_sig & 1u));
-        round_up = fractional + half_ulp < fractional;
-        round_down = half_ulp > fractional;
-        // the last digit of the longer candidate, rounded to nearest
-        digit = umul128_add_hi64(fractional, 10, (std::uint64_t{1} << 63u) + 6);
-        if (fractional == (std::uint64_t{1} << 62u))
-        {
-            digit = 2; // 2.5 rounds to 2
-        }
-    }
-    else
-    {
-        const std::uint64_t half_ulp = p10.high >> static_cast<unsigned>(extra_shift + 1 - shift);
-        round_up = half_ulp > ~std::uint64_t{0} - fractional;
-        round_down = (half_ulp >> 1u) > fractional;
-        digit = umul128_add_hi64(fractional, 10, (std::uint64_t{1} << 63u) - 1);
-        const std::uint64_t lowest = umul128_add_hi64(fractional - (half_ulp >> 1u), 10, ~std::uint64_t{0});
-        digit = digit < lowest ? lowest : digit;
-    }
-    integral += round_up ? 1u : 0u;
-    // if the shorter candidate is outside the rounding interval: one digit more
-    return shortest_decimal{integral, dec_exp, static_cast<unsigned char>(digit), !round_up && !round_down};
-}
-
-}  // namespace zmij
-}  // namespace detail
-NLOHMANN_JSON_NAMESPACE_END
@@ -14,10 +14,12 @@
 #include <cstdint> // uint32_t
 #include <cstring> // strlen
 #include <iterator> // begin, end, iterator_traits, random_access_iterator_tag, distance, next, reverse_iterator
+#include <limits> // numeric_limits
 #include <streambuf> // streambuf
 #include <string> // string, char_traits
 #include <type_traits> // enable_if, is_base_of, is_pointer, is_integral, remove_pointer
 #include <utility> // pair, declval
+#include <vector> // vector

 #ifndef JSON_NO_IO
    #include <cstdio>   // FILE *
@@ -30,6 +32,24 @@
 #include <nlohmann/detail/meta/type_traits.hpp>
 #include <nlohmann/detail/string_utils.hpp>

+#ifndef JSON_NO_IO
+    // Which unlocked stdio functions file_input_adapter uses (see
+    // JSON_DISABLE_UNLOCKED_FILE_IO): 1 = POSIX flockfile/getc_unlocked,
+    // 2 = Microsoft CRT _lock_file/_fgetc_nolock, 0 = none (std::fgetc, which
+    // locks the file for every character). Only C libraries known to declare
+    // the functions are listed; the macros are tested after <cstdio>, which
+    // defines __GLIBC__.
+    #if JSON_DISABLE_UNLOCKED_FILE_IO
+        #define JSON_UNLOCKED_FILE_IO 0
+    #elif defined(_MSC_VER)
+        #define JSON_UNLOCKED_FILE_IO 2
+    #elif defined(__GLIBC__) || defined(__APPLE__) || defined(__ANDROID__) || defined(__FreeBSD__) || defined(__NetBSD__) || defined(__OpenBSD__) || defined(__DragonFly__)
+        #define JSON_UNLOCKED_FILE_IO 1
+    #else
+        #define JSON_UNLOCKED_FILE_IO 0
+    #endif
+#endif  // JSON_NO_IO
+
 NLOHMANN_JSON_NAMESPACE_BEGIN
 namespace detail
 {
@@ -56,18 +76,38 @@ class file_input_adapter
        : m_file(f)
    {
        JSON_ASSERT(m_file != nullptr);
+        lock();
    }

    // make class move-only
    file_input_adapter(const file_input_adapter&) = delete;
-    file_input_adapter(file_input_adapter&&) noexcept = default;
+    file_input_adapter(file_input_adapter&& rhs) noexcept
+        : m_file(rhs.m_file)
+    {
+        // the lock is owned by the thread, not the adapter: hand it over
+        rhs.m_file = nullptr;
+    }
    file_input_adapter& operator=(const file_input_adapter&) = delete;
    file_input_adapter& operator=(file_input_adapter&&) = delete;
-    ~file_input_adapter() = default;
+    ~file_input_adapter()
+    {
+        if (m_file != nullptr)
+        {
+            unlock();
+        }
+    }

    std::char_traits<char>::int_type get_character() noexcept
    {
+        // the file is locked for the lifetime of the adapter, so the
+        // per-character lock of std::fgetc can be skipped
+#if JSON_UNLOCKED_FILE_IO == 1
+        return getc_unlocked(m_file);
+#elif JSON_UNLOCKED_FILE_IO == 2
+        return _fgetc_nolock(m_file);
+#else
        return std::fgetc(m_file);
+#endif
    }

    // returns the number of characters successfully read
@@ -78,6 +118,27 @@ class file_input_adapter
    }

  private:
+    // Lock the file once for the whole parse instead of once per character.
+    // The lock is recursive, so fread() and the user's own stdio calls on the
+    // same thread keep working.
+    void lock() noexcept
+    {
+#if JSON_UNLOCKED_FILE_IO == 1
+        flockfile(m_file);
+#elif JSON_UNLOCKED_FILE_IO == 2
+        _lock_file(m_file);
+#endif
+    }
+
+    void unlock() noexcept
+    {
+#if JSON_UNLOCKED_FILE_IO == 1
+        funlockfile(m_file);
+#elif JSON_UNLOCKED_FILE_IO == 2
+        _unlock_file(m_file);
+#endif
+    }
+
    /// the file pointer to read from
    std::FILE* m_file;
 };
@@ -127,15 +188,26 @@ class input_stream_adapter
    input_stream_adapter& operator=(input_stream_adapter&) = delete;
    input_stream_adapter& operator=(input_stream_adapter&&) = delete;

-#if JSON_PRECISE_STREAM_POSITION
    input_stream_adapter(input_stream_adapter&& rhs) noexcept
-        : is(rhs.is), sb(rhs.sb), lookahead(rhs.lookahead)
+        : is(rhs.is), sb(rhs.sb)
+#if JSON_PRECISE_STREAM_POSITION
+        , lookahead(rhs.lookahead)
+#endif
+#if !JSON_DISABLE_STREAM_BULK_SCAN
+        , token_carry(std::move(rhs.token_carry))
+        , token_segment(rhs.token_segment)
+        , current_in_get_area(rhs.current_in_get_area)
+        , tracking_token(rhs.tracking_token)
+#endif
    {
        rhs.is = nullptr;
        rhs.sb = nullptr;
+#if JSON_PRECISE_STREAM_POSITION
        rhs.lookahead = false;
+#endif
    }

+#if JSON_PRECISE_STREAM_POSITION
    // Whether the character last returned by get_character() can be given back
    // to the input with release_lookahead().
    static constexpr bool supports_lookahead = true;
@@ -155,17 +227,41 @@ class input_stream_adapter
            sb->sbumpc();
        }

+#if !JSON_DISABLE_STREAM_BULK_SCAN
+        // sgetc() refills the get area if it is exhausted
+        const bool refill = streambuf_access::get_ptr(sb) == streambuf_access::get_end(sb);
+        if (JSON_HEDLEY_UNLIKELY(refill))
+        {
+            save_token_segment();
+        }
+#endif
+
        auto res = sb->sgetc();
        // set eof manually, as we don't use the istream interface.
        if (JSON_HEDLEY_UNLIKELY(res == std::char_traits<char>::eof()))
        {
            // there is nothing to step over next time
            lookahead = false;
+#if !JSON_DISABLE_STREAM_BULK_SCAN
+            current_in_get_area = false;
+#endif
            is->clear(is->rdstate() | std::ios::eofbit);
        }
        else
        {
            lookahead = true;
+#if !JSON_DISABLE_STREAM_BULK_SCAN
+            if (JSON_HEDLEY_UNLIKELY(refill))
+            {
+                // the peeked character is at gptr(), unless the streambuf has
+                // no get area
+                after_refill(res, streambuf_access::get_ptr(sb) != streambuf_access::get_end(sb));
+            }
+            else
+            {
+                current_in_get_area = true;
+            }
+#endif
        }
        return res;
    }
@@ -179,13 +275,6 @@ class input_stream_adapter
        lookahead = false;
    }
 #else
-    input_stream_adapter(input_stream_adapter&& rhs) noexcept
-        : is(rhs.is), sb(rhs.sb)
-    {
-        rhs.is = nullptr;
-        rhs.sb = nullptr;
-    }
-
    // std::istream/std::streambuf use std::char_traits<char>::to_int_type, to
    // ensure that std::char_traits<char>::eof() and the character 0xFF do not
    // end up as the same value, e.g., 0xFFFFFFFF.
@@ -194,12 +283,37 @@ class input_stream_adapter
    // stays consumed after parsing; see JSON_PRECISE_STREAM_POSITION.
    std::char_traits<char>::int_type get_character()
    {
+#if !JSON_DISABLE_STREAM_BULK_SCAN
+        // sbumpc() refills the get area if it is exhausted
+        const bool refill = streambuf_access::get_ptr(sb) == streambuf_access::get_end(sb);
+        if (JSON_HEDLEY_UNLIKELY(refill))
+        {
+            save_token_segment();
+        }
+#endif
+
        auto res = sb->sbumpc();
        // set eof manually, as we don't use the istream interface.
        if (JSON_HEDLEY_UNLIKELY(res == std::char_traits<char>::eof()))
        {
+#if !JSON_DISABLE_STREAM_BULK_SCAN
+            current_in_get_area = false;
+#endif
            is->clear(is->rdstate() | std::ios::eofbit);
        }
+#if !JSON_DISABLE_STREAM_BULK_SCAN
+        else if (JSON_HEDLEY_UNLIKELY(refill))
+        {
+            // the consumed character is at gptr() - 1, unless the streambuf
+            // has no get area and returned it from uflow()
+            const char* const next = streambuf_access::get_ptr(sb);
+            after_refill(res, next != nullptr && next != streambuf_access::get_begin(sb));
+        }
+        else
+        {
+            current_in_get_area = true;
+        }
+#endif
        return res;
    }
 #endif
@@ -218,7 +332,165 @@ class input_stream_adapter
        return res;
    }

+#if !JSON_DISABLE_STREAM_BULK_SCAN
+    // The lexer may scan the characters in the get area of the streambuf
+    // directly (SWAR fast paths). The get area is only a window into the
+    // input: it ends wherever the streambuf's buffer ends, and is refilled by
+    // the next get_character(). The lexer therefore keeps counting the
+    // position itself and treats the end of the window as "unknown", not as
+    // the end of the input.
+    static constexpr bool supports_bulk_scan = true;
+    static constexpr bool bulk_window = true;
+
+    // Pointer to the next unread character; only valid when
+    // bulk_remaining() > 0. The character before it is the one last returned
+    // by get_character().
+    const char* bulk_data() const
+    {
+        return current_end();
+    }
+
+    // Number of unread characters in the get area.
+    std::size_t bulk_remaining() const
+    {
+        if (!current_in_get_area)
+        {
+            return 0;
+        }
+        return static_cast<std::size_t>(streambuf_access::get_end(sb) - current_end());
+    }
+
+    // Consume @a n characters previously inspected via bulk_data(); the last
+    // of them becomes the character last returned by get_character().
+    void bulk_skip(std::size_t n)
+    {
+        JSON_ASSERT(n <= bulk_remaining());
+        // gbump() takes an int, but a get area (e.g., of a std::stringbuf) can
+        // be larger
+        constexpr auto max_bump = static_cast<std::size_t>((std::numeric_limits<int>::max)());
+        for (; n > max_bump; n -= max_bump)
+        {
+            streambuf_access::bump(sb, static_cast<int>(max_bump));
+        }
+        streambuf_access::bump(sb, static_cast<int>(n));
+    }
+
+    // The adapter keeps the current token for the lexer's error messages: the
+    // part in the get area is only remembered as a pointer, and copied out
+    // when the get area is about to be refilled.
+    static constexpr bool supports_token_tracking = true;
+
+    // Start a token with the characters read from now on. Until this is
+    // called, nothing is tracked (the binary readers never call it).
+    void begin_token() noexcept
+    {
+        tracking_token = true;
+        token_carry.clear();
+        token_segment = current_end();
+    }
+
+    // Start a new token with the character @a c last returned by
+    // get_character().
+    void mark_token_start(std::char_traits<char>::int_type c)
+    {
+        tracking_token = true;
+        token_carry.clear();
+        if (current_in_get_area)
+        {
+            token_segment = current_end() - 1;
+        }
+        else
+        {
+            token_segment = nullptr;
+            token_carry.push_back(std::char_traits<char>::to_char_type(c));
+        }
+    }
+
+    // Copy the characters read since mark_token_start() to @a out, without the
+    // last one if @a drop_last.
+    void copy_token(std::vector<char>& out, bool drop_last) const
+    {
+        out = token_carry;
+        if (token_segment != nullptr)
+        {
+            out.insert(out.end(), token_segment, current_end());
+        }
+        if (drop_last && !out.empty())
+        {
+            out.pop_back();
+        }
+    }
+#endif
+
  private:
+#if !JSON_DISABLE_STREAM_BULK_SCAN
+    // Reads the protected get-area pointers of any std::streambuf. Naming the
+    // members through a derived class makes forming the member pointers
+    // accessible; calling them on another streambuf object is then ordinary
+    // member access through a pointer to member.
+    struct streambuf_access : std::streambuf
+    {
+        static const char* get_ptr(std::streambuf* s)
+        {
+            return (s->*(&streambuf_access::gptr))();
+        }
+        static const char* get_end(std::streambuf* s)
+        {
+            return (s->*(&streambuf_access::egptr))();
+        }
+        static const char* get_begin(std::streambuf* s)
+        {
+            return (s->*(&streambuf_access::eback))();
+        }
+        static void bump(std::streambuf* s, int n)
+        {
+            (s->*(&streambuf_access::gbump))(n);
+        }
+    };
+
+    // one past the character last returned by get_character(), if that is in
+    // the get area
+    const char* current_end() const
+    {
+#if JSON_PRECISE_STREAM_POSITION
+        // the character is peeked at gptr() and not stepped over yet, unless
+        // it was given back with release_lookahead()
+        return streambuf_access::get_ptr(sb) + (lookahead ? 1 : 0);
+#else
+        return streambuf_access::get_ptr(sb);
+#endif
+    }
+
+    // the get area is about to be replaced: copy the token's part in it
+    void save_token_segment()
+    {
+        if (token_segment != nullptr)
+        {
+            token_carry.insert(token_carry.end(), token_segment, streambuf_access::get_end(sb));
+            token_segment = nullptr;
+        }
+    }
+
+    // character @a c was just read into a new get area (@a in_get_area) or
+    // returned without one
+    void after_refill(std::char_traits<char>::int_type c, bool in_get_area)
+    {
+        current_in_get_area = in_get_area;
+        if (!tracking_token)
+        {
+            return;
+        }
+        if (in_get_area)
+        {
+            token_segment = current_end() - 1;
+        }
+        else
+        {
+            token_carry.push_back(std::char_traits<char>::to_char_type(c));
+        }
+    }
+#endif
+
 #if JSON_PRECISE_STREAM_POSITION
    // Step over the character last returned by get_character(). The character
    // has already been peeked successfully, so for every streambuf with a get
@@ -240,6 +512,16 @@ class input_stream_adapter
    /// whether get_character() peeked a character that is not consumed yet
    bool lookahead = false;
 #endif
+#if !JSON_DISABLE_STREAM_BULK_SCAN
+    /// the part of the current token that was in earlier get areas
+    std::vector<char> token_carry{}; // NOLINT(readability-redundant-member-init)
+    /// start of the current token's part in the get area, or nullptr
+    const char* token_segment = nullptr;
+    /// whether the character last returned by get_character() is in the get area
+    bool current_in_get_area = false;
+    /// whether a token is tracked at all; the binary readers never start one
+    bool tracking_token = false;
+#endif
 };
 #endif  // JSON_NO_IO

@@ -166,6 +166,43 @@ constexpr bool input_adapter_supports_bulk_scan(std::false_type /*detected*/)
    return false;
 }

+// Detect whether an input adapter keeps the current token itself and can
+// hand it out on demand (see input_stream_adapter::supports_token_tracking),
+// so the lexer need not copy every scanned character into token_string.
+template<typename InputAdapterType>
+using detect_supports_token_tracking = decltype(InputAdapterType::supports_token_tracking);
+
+template<typename InputAdapterType>
+constexpr bool input_adapter_supports_token_tracking(std::true_type /*detected*/)
+{
+    return InputAdapterType::supports_token_tracking;
+}
+
+template<typename InputAdapterType>
+constexpr bool input_adapter_supports_token_tracking(std::false_type /*detected*/)
+{
+    return false;
+}
+
+// Detect whether the contiguous block of a bulk-scan adapter is only a window
+// into the input (see input_stream_adapter::bulk_window): its end is not the
+// end of the input, so a token that touches it must be finished character by
+// character.
+template<typename InputAdapterType>
+using detect_bulk_window = decltype(InputAdapterType::bulk_window);
+
+template<typename InputAdapterType>
+constexpr bool input_adapter_bulk_window(std::true_type /*detected*/)
+{
+    return InputAdapterType::bulk_window;
+}
+
+template<typename InputAdapterType>
+constexpr bool input_adapter_bulk_window(std::false_type /*detected*/)
+{
+    return false;
+}
+
 /*!
@brief lexical analysis

@@ -184,9 +221,20 @@ class lexer : public lexer_base<BasicJsonType>
    /// whether the last read token can be reconstructed from the input adapter
    /// on demand (in error paths) instead of being copied on every scanned
    /// character; see input_adapter_supports_seek
-    static constexpr bool lazy_token_string =
+    static constexpr bool seekable =
        input_adapter_supports_seek<InputAdapterType>(is_detected<detect_supports_seek, InputAdapterType> {});

+    /// whether the adapter keeps the token itself (mark_token_start() /
+    /// copy_token()); see input_adapter_supports_token_tracking
+    static constexpr bool adapter_token =
+        !seekable && input_adapter_supports_token_tracking<InputAdapterType>(is_detected<detect_supports_token_tracking, InputAdapterType> {});
+
+    /// whether the last read token is obtained from the input adapter on
+    /// demand (in error paths) instead of being copied on every scanned
+    /// character: seekable adapters reconstruct it from the consumed input,
+    /// token-tracking adapters keep it themselves
+    static constexpr bool lazy_token_string = seekable || adapter_token;
+
    /// whether the read position is derived from the input adapter on demand
    /// instead of being counted on every scanned character. Seekable adapters
    /// know how much input they consumed and can revisit it, so
@@ -194,7 +242,7 @@ class lexer : public lexer_base<BasicJsonType>
    /// and line and column are recomputed from the consumed input only when
    /// get_position() is called (errors). Counting per character kept two
    /// increments and a newline check in the hot path of every get().
-    static constexpr bool lazy_position = lazy_token_string;
+    static constexpr bool lazy_position = seekable;

    /// whether a simulated unget can be passed on to the input adapter, which
    /// then leaves the character in the input; see
@@ -203,14 +251,17 @@ class lexer : public lexer_base<BasicJsonType>
        input_adapter_supports_lookahead<InputAdapterType>(is_detected<detect_supports_lookahead, InputAdapterType> {});

    /// whether string scanning may bulk-consume runs of ordinary characters
-    /// directly from a contiguous input buffer (SWAR fast path). This requires
-    /// the token to be reconstructible lazily (lazy_token_string), so bypassing
-    /// the per-character capture in get() cannot lose error diagnostics. It
-    /// also implies lazy_position, so the bulk paths need not advance the
-    /// position counters.
+    /// directly from a contiguous input buffer (SWAR fast path). Without
+    /// lazy_token_string / lazy_position, the bulk paths copy the consumed
+    /// characters into token_string and advance the position counters
+    /// themselves (see bulk_consume).
    static constexpr bool bulk_scan =
-        lazy_token_string
-        && input_adapter_supports_bulk_scan<InputAdapterType>(is_detected<detect_supports_bulk_scan, InputAdapterType> {});
+        input_adapter_supports_bulk_scan<InputAdapterType>(is_detected<detect_supports_bulk_scan, InputAdapterType> {});
+
+    /// whether the contiguous block is only a window into the input, so that
+    /// its end does not end a token; see input_adapter_bulk_window
+    static constexpr bool bulk_window =
+        input_adapter_bulk_window<InputAdapterType>(is_detected<detect_bulk_window, InputAdapterType> {});

  public:
    using token_type = typename lexer_base<BasicJsonType>::token_type;
@@ -219,7 +270,11 @@ class lexer : public lexer_base<BasicJsonType>
        : ia(std::move(adapter))
        , ignore_comments(ignore_comments_)
        , discard_number_values(discard_number_values_)
-    {}
+    {
+        // the token string of an error before the first token is everything
+        // read so far
+        begin_token(std::integral_constant<bool, adapter_token> {});
+    }

    // deleted because of pointer members
    lexer(const lexer&) = delete;
@@ -233,41 +288,6 @@ class lexer : public lexer_base<BasicJsonType>
    // scan functions
    /////////////////////

-    /// contiguous input: try to decode the 4 hex digits following `\\u`
-    /// directly from the input buffer via hex_codepoint(), instead of 4 calls
-    /// to get(). On success, advances the adapter exactly as those 4 get()
-    /// calls would (bulk_scan implies lazy_position, so there are no position
-    /// counters to advance) and leaves @a current holding the last of
-    /// the 4 digits, just as the last such get() would; the codepoint is
-    /// written to @a out. Makes no state change and returns false for a
-    /// pending unget, fewer than 4 remaining bytes, or any of the 4 bytes not
-    /// being a hex digit, so the caller falls back unchanged to the
-    /// per-character loop, which then reports the same diagnostic (stopping
-    /// at the first invalid digit) as before this optimization.
-    bool get_codepoint_bulk(std::true_type /*bulk*/, int& out)
-    {
-        if (next_unget || ia.bulk_remaining() < 4)
-        {
-            return false;
-        }
-        const char_type* const raw = ia.bulk_data();
-        const int codepoint = hex_codepoint(reinterpret_cast<const unsigned char*>(raw));
-        if (codepoint < 0)
-        {
-            return false;
-        }
-        ia.bulk_skip(4);
-        current = char_traits<char_type>::to_int_type(raw[3]);
-        out = codepoint;
-        return true;
-    }
-
-    /// streaming input: no bulk fast path
-    bool get_codepoint_bulk(std::false_type /*bulk*/, int& /*out*/) const noexcept
-    {
-        return false;
-    }
-
    /*!
    @brief get codepoint from 4 hex characters following `\\u`

@@ -287,14 +307,6 @@ class lexer : public lexer_base<BasicJsonType>
    {
        // this function only makes sense after reading `\u`
        JSON_ASSERT(current == 'u');
-
-        // contiguous input: decode all 4 hex digits directly from the buffer
-        int fast_codepoint = 0;
-        if (get_codepoint_bulk(std::integral_constant<bool, bulk_scan> {}, fast_codepoint))
-        {
-            return fast_codepoint;
-        }
-
        int codepoint = 0;

        const auto factors = { 12u, 8u, 4u, 0u };
@@ -385,7 +397,36 @@ class lexer : public lexer_base<BasicJsonType>
            return;
        }
        token_buffer.append(reinterpret_cast<const typename string_t::value_type*>(data), pos);
-        ia.bulk_skip(pos);
+        bulk_consume(reinterpret_cast<const char*>(data), pos);
+    }
+
+    /// consume @a n characters at @a data (the adapter's bulk_data()) and do
+    /// the bookkeeping get() would have done for them; the characters are
+    /// never newlines
+    void bulk_consume(const char* data, std::size_t n)
+    {
+        bulk_track_position(n, std::integral_constant<bool, lazy_position> {});
+        bulk_track_token(data, n, std::integral_constant<bool, lazy_token_string> {});
+        ia.bulk_skip(n);
+    }
+
+    /// seekable adapter: the position is derived from the adapter
+    void bulk_track_position(std::size_t /*n*/, std::true_type /*lazy*/) const noexcept {}
+
+    /// streaming adapter: count the characters
+    void bulk_track_position(std::size_t n, std::false_type /*lazy*/) noexcept
+    {
+        position.chars_read_total += n;
+        position.chars_read_current_line += n;
+    }
+
+    /// the token is obtained from the adapter
+    void bulk_track_token(const char* /*data*/, std::size_t /*n*/, std::true_type /*lazy*/) const noexcept {}
+
+    /// streaming adapter: capture the characters
+    void bulk_track_token(const char* data, std::size_t n, std::false_type /*lazy*/)
+    {
+        token_string.insert(token_string.end(), data, data + n);
    }

    /// streaming input: no bulk fast path
@@ -1095,11 +1136,9 @@ class lexer : public lexer_base<BasicJsonType>
            token_type::parse_error otherwise

    @note The scanner is independent of the current locale: token_buffer
-          always holds `.`. The conversion of float and double does not use
-          the locale either. Only the std::strtold fallback of
-          convert_number() for long double formats other than binary64
-          depends on it, and it looks up the decimal point right before
-          converting (see detail::convert_float_locale_aware()).
+          always holds `.`. Only the std::strtod fallback of convert_number()
+          depends on the locale, and it looks up the decimal point right
+          before converting (see detail::convert_float_locale_aware()).
    */
    token_type scan_number()  // lgtm [cpp/use-of-goto] `goto` is used in this function to implement the number-parsing state machine described above. By design, any finite input will eventually reach the "done" state or return token_type::parse_error. In each intermediate state, 1 byte of the input is appended to the token_buffer vector, and only the already initialized variables token_buffer, number_type, and error_message are manipulated.
    {
@@ -1112,7 +1151,7 @@ class lexer : public lexer_base<BasicJsonType>

        // offset just past the last mantissa byte in token_buffer (i.e. the
        // index of 'e'/'E', or the whole token when there is no exponent).
-        // convert_number() uses it to split the token; npos means
+        // convert_number() uses it to count significant digits; npos means
        // "not seen an exponent yet" and is resolved at scan_number_done
        std::size_t mantissa_end = std::string::npos;

@@ -1442,8 +1481,8 @@ scan_number_done:
    @param[in] mantissa_end  offset just past the last mantissa byte in
                             token_buffer (the index of 'e'/'E', or
                             token_buffer.size() when there is no exponent);
-                             with decimal_point_position, it locates the parts
-                             of a float token without scanning it again
+                             used to skip Clinger's fast path when it cannot
+                             possibly succeed - see detail::mantissa_fits_clinger()
    */
    token_type convert_number(token_type number_type, std::size_t mantissa_end)
    {
@@ -1497,11 +1536,10 @@ scan_number_done:
        }

        // this code is reached if we parse a floating-point number or if an
-        // integer conversion above overflowed. float and double (and long
-        // double where it is binary64) are converted by the library itself,
-        // correctly rounded and independent of the locale; other long double
-        // formats use std::from_chars when available, otherwise the
-        // locale-aware strtold.
+        // integer conversion above overflowed. Prefer std::from_chars
+        // (Eisel-Lemire, locale-independent, correctly rounded) when available;
+        // otherwise the exact Clinger fast path (double only); otherwise the
+        // locale-aware strtof/strtod/strtold.
        if (convert_float_fast(num_begin, num_end, decimal_point_position, mantissa_end, value_float))
        {
            return token_type::value_float;
@@ -1603,6 +1641,10 @@ scan_number_done:
            }
        }
        const std::size_t len = i;
+        if (number_may_continue(len == avail, std::integral_constant<bool, bulk_window> {}))
+        {
+            return token_type::uninitialized;
+        }

        // reset() records where this token starts (for diagnostics), so it has
        // to run before the input position advances below
@@ -1620,7 +1662,8 @@ scan_number_done:
            const token_type integer_result = convert_integer(number_type, data, data + len);
            if (JSON_HEDLEY_LIKELY(integer_result != token_type::uninitialized))
            {
-                ia.bulk_skip(len - 1);
+                bulk_consume(data + 1, len - 1);
+                read_number_terminator(std::integral_constant<bool, bulk_window> {});
                return integer_result;
            }
            // The value does not fit an integer, so this token converts as a
@@ -1636,11 +1679,37 @@ scan_number_done:
        token_buffer.append(reinterpret_cast<const typename string_t::value_type*>(data), len);
        decimal_point_position = dot_index;

-        ia.bulk_skip(len - 1);
+        bulk_consume(data + 1, len - 1);
+        read_number_terminator(std::integral_constant<bool, bulk_window> {});

        return convert_number(number_type, mantissa_end);
    }

+    /// window adapter: a number that reaches the end of the window may continue
+    /// after it, so scan_number() has to read it character by character
+    static constexpr bool number_may_continue(bool at_end, std::true_type /*window*/) noexcept
+    {
+        return at_end;
+    }
+
+    /// the end of the block is the end of the input, which ends the number
+    static constexpr bool number_may_continue(bool /*at_end*/, std::false_type /*window*/) noexcept
+    {
+        return false;
+    }
+
+    /// window adapter: read the character after a bulk-scanned number and unget
+    /// it, as scan_number() does. The adapter is a stream that is handed back to
+    /// the user, who must find the same input consumed either way.
+    void read_number_terminator(std::true_type /*window*/)
+    {
+        get();
+        unget();
+    }
+
+    /// the input is not handed back, so the terminator can stay unread
+    void read_number_terminator(std::false_type /*window*/) const noexcept {}
+
    /// contiguous input: try the number fast path, else the byte-path scanner
    token_type scan_number_dispatch(std::true_type /*bulk*/)
    {
@@ -1696,11 +1765,30 @@ scan_number_done:
    /// seekable adapter: remember where the current token starts so it can be
    /// reconstructed from the input on error; current has already been
    /// consumed, hence the -1
-    void note_token_start(std::true_type /*lazy*/) noexcept
+    void note_token_start(std::true_type /*lazy*/)
+    {
+        note_token_start_lazy(std::integral_constant<bool, adapter_token> {});
+    }
+
+    void note_token_start_lazy(std::false_type /*adapter_token*/) noexcept
    {
        token_string_start = ia.get_consumed_count() - 1;
    }

+    /// token-tracking adapter: start tracking the token at the first character
+    void begin_token(std::true_type /*adapter_token*/) noexcept
+    {
+        ia.begin_token();
+    }
+
+    void begin_token(std::false_type /*adapter_token*/) const noexcept {}
+
+    /// token-tracking adapter: the token starts with the current character
+    void note_token_start_lazy(std::true_type /*adapter_token*/)
+    {
+        ia.mark_token_start(current);
+    }
+
    /// streaming adapter: start copying the token eagerly, beginning with the
    /// already-read first character
    void note_token_start(std::false_type /*lazy*/) noexcept
@@ -2021,6 +2109,20 @@ scan_number_done:
  public:
    /// seekable adapter: rebuild the last read token from the input on demand
    const std::vector<char_type>& collect_token_chars(std::vector<char_type>& out, std::true_type /*lazy*/) const
+    {
+        return collect_token_chars_lazy(out, std::integral_constant<bool, adapter_token> {});
+    }
+
+    /// token-tracking adapter: the adapter hands out everything read since
+    /// mark_token_start(), except a pending unget (see below)
+    const std::vector<char_type>& collect_token_chars_lazy(std::vector<char_type>& out, std::true_type /*adapter_token*/) const
+    {
+        const bool pending_real_unget = next_unget && current != char_traits<char_type>::eof();
+        ia.copy_token(out, pending_real_unget);
+        return out;
+    }
+
+    const std::vector<char_type>& collect_token_chars_lazy(std::vector<char_type>& out, std::false_type /*adapter_token*/) const
    {
        // a pending unget of a real (non-EOF) character means that character
        // was consumed from the input but is not part of the token; EOF is
@@ -2142,9 +2244,8 @@ scan_number_done:
    Pretty-printed JSON indents every line with a run of spaces, which the loop
    in skip_whitespace() would otherwise read one character at a time. The
    spaces are skipped 8 bytes at a time; the last 7 bytes of the input and any
-    other whitespace are left to that loop. Skipping bypasses get(), which is
-    fine because bulk_scan implies lazy_position: the position is derived from
-    the adapter, not counted per character.
+    other whitespace are left to that loop. Skipping bypasses get();
+    bulk_consume() does its bookkeeping.
    */
    void skip_indentation(std::true_type /*bulk*/)
    {
@@ -2167,7 +2268,7 @@ scan_number_done:
                break;
            }
        }
-        ia.bulk_skip(pos);
+        bulk_consume(data, pos);
    }

    /// streaming input: no bulk fast path
@@ -22,10 +22,6 @@ namespace detail
 constexpr std::int64_t pow5_128_smallest_power = -342;
 constexpr std::int64_t pow5_128_largest_power = 308;

-// every entry of pow5_128() holds two 64-bit halves of 5^q, one per covered power of 5
-static_assert((pow5_128_largest_power - pow5_128_smallest_power + 1) * 2 == 1302,
-              "pow5_128_smallest_power/pow5_128_largest_power must match the size of the pow5_128() table");
-
 /*!
@brief 128-bit approximations of 5^q for q in [-342, 308]

@@ -8,12 +8,10 @@

 #pragma once

-#include <array> // array
 #include <cstddef> // size_t
-#include <cstdint> // uint64_t, uint8_t
+#include <cstdint> // uint64_t
 #include <cstring> // memcpy

-#include <nlohmann/detail/bit_ops.hpp>
 #include <nlohmann/detail/macro_scope.hpp>

 // Optional SIMD backend for bulk UTF-8 validation. This is an opt-in external
@@ -71,12 +69,18 @@ inline std::size_t find_string_special(const unsigned char* data, std::size_t n)
    std::size_t i = 0;
    for (; i + 8 <= n; i += 8)
    {
-        const std::uint64_t special = swar_string_special(read_eight_bytes(data + i));
-        if (special != 0)
+        std::uint64_t word = 0;
+        std::memcpy(&word, data + i, sizeof(word));
+        if (swar_string_special(word) != 0)
        {
-            // the lowest flagged byte is the first special one: the borrows of
-            // the subtractions can only flag bytes above a true hit
-            return i + (static_cast<std::size_t>(count_trailing_zeros(special)) / 8);
+            // a special byte is in this word; locate it (endian-agnostic)
+            for (std::size_t j = 0; j < 8; ++j)
+            {
+                if (is_string_special(data[i + j]))
+                {
+                    return i + j;
+                }
+            }
        }
    }
    for (; i < n; ++i)
@@ -110,7 +114,8 @@ inline std::size_t find_ascii_copyable_run(const unsigned char* data, std::size_
    std::size_t i = 0;
    for (; i + 8 <= n; i += 8)
    {
-        const std::uint64_t v = read_eight_bytes(data + i);
+        std::uint64_t v = 0;
+        std::memcpy(&v, data + i, sizeof(v));
        const std::uint64_t q = v ^ 0x2222222222222222ull; // '"'  (0x22)
        const std::uint64_t b = v ^ 0x5C5C5C5C5C5C5C5Cull; // '\\' (0x5C)
        const std::uint64_t d = v ^ 0x7F7F7F7F7F7F7F7Full; // DEL  (0x7F)
@@ -121,9 +126,7 @@ inline std::size_t find_ascii_copyable_run(const unsigned char* data, std::size_
                                   | (v & high);               // >= 0x80
        if (stop != 0)
        {
-            // the lowest flagged byte is the first one to stop at (see
-            // find_string_special())
-            return i + (static_cast<std::size_t>(count_trailing_zeros(stop)) / 8);
+            break;
        }
    }
    for (; i < n; ++i)
@@ -250,18 +253,12 @@ inline std::size_t scalar_string_bulk_run(const unsigned char* data, std::size_t
        {
            break; // end of buffer, or a quote/escape/control byte
        }
-        // a run of multi-byte sequences (e.g. CJK text) is validated sequence
-        // by sequence without searching for the next special byte in between
-        do
+        const std::size_t seq = validate_one_utf8(data + pos, n - pos);
+        if (seq == 0)
        {
-            const std::size_t seq = validate_one_utf8(data + pos, n - pos);
-            if (seq == 0)
-            {
-                return pos; // ill-formed or truncated: let the byte path diagnose it
-            }
-            pos += seq;
+            break; // ill-formed or truncated: let the byte path diagnose it
        }
-        while (pos < n && data[pos] >= 0x80u);
+        pos += seq;
    }
    return pos;
 }
@@ -276,7 +273,8 @@ inline std::size_t find_string_delimiter(const unsigned char* data, std::size_t
    std::size_t i = 0;
    for (; i + 8 <= n; i += 8)
    {
-        const std::uint64_t v = read_eight_bytes(data + i);
+        std::uint64_t v = 0;
+        std::memcpy(&v, data + i, sizeof(v));
        const std::uint64_t q = v ^ 0x2222222222222222ull;
        const std::uint64_t b = v ^ 0x5C5C5C5C5C5C5C5Cull;
        const std::uint64_t hit = ((q - ones) & ~q & high)
@@ -284,8 +282,14 @@ inline std::size_t find_string_delimiter(const unsigned char* data, std::size_t
                                  | ((v - 0x2020202020202020ull) & ~v & high);
        if (hit != 0)
        {
-            // the lowest flagged byte is the first delimiter (see find_string_special())
-            return i + (static_cast<std::size_t>(count_trailing_zeros(hit)) / 8);
+            for (std::size_t j = 0; j < 8; ++j)
+            {
+                const unsigned char c = data[i + j];
+                if (c == '\"' || c == '\\' || c < 0x20u)
+                {
+                    return i + j;
+                }
+            }
        }
    }
    for (; i < n; ++i)
@@ -316,50 +320,5 @@ inline std::size_t string_bulk_run(const unsigned char* data, std::size_t n) noe
    return scalar_string_bulk_run(data, n);
 }

-// Decode the 4 hex digits at [data, data+4) - the digits following a `\u`
-// escape - into a codepoint 0x0000..0xFFFF via one table lookup per byte
-// (after yyjson's read_hex_u16), or return -1 if any of the 4 bytes is not a
-// hex digit ('0'..'9', 'A'..'F', 'a'..'f'). The caller must already have
-// checked that 4 bytes are available; used by lexer::get_codepoint()'s
-// contiguous fast path. On -1 it falls back to the byte-at-a-time loop, which
-// stops at the first invalid digit, so the reported error and position are
-// unaffected by this fast path.
-inline int hex_codepoint(const unsigned char* data) noexcept
-{
-    static const std::array<std::uint8_t, 256> hex_digit_table = // NOLINT(cppcoreguidelines-avoid-non-const-global-variables)
-    {
-        {
-            0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, // 00..0F
-            0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, // 10..1F
-            0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, // 20..2F
-            0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, // 30..3F ('0'..'9')
-            0xFF, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, // 40..4F ('A'..'F')
-            0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, // 50..5F
-            0xFF, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, // 60..6F ('a'..'f')
-            0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, // 70..7F
-            0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, // 80..8F
-            0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, // 90..9F
-            0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, // A0..AF
-            0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, // B0..BF
-            0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, // C0..CF
-            0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, // D0..DF
-            0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, // E0..EF
-            0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF  // F0..FF
-        }
-    };
-
-    const std::uint8_t d0 = hex_digit_table[data[0]];
-    const std::uint8_t d1 = hex_digit_table[data[1]];
-    const std::uint8_t d2 = hex_digit_table[data[2]];
-    const std::uint8_t d3 = hex_digit_table[data[3]];
-    // every valid digit is <= 0xF; the combined OR only exceeds it if at
-    // least one of the four bytes was not a hex digit (looked up as 0xFF)
-    if ((d0 | d1 | d2 | d3) > 0x0F)
-    {
-        return -1;
-    }
-    return (d0 << 12) | (d1 << 8) | (d2 << 4) | d3;
-}
-
 }  // namespace detail
 NLOHMANN_JSON_NAMESPACE_END
@@ -895,3 +895,11 @@
 #ifndef JSON_DISABLE_TUPLE_REFERENCE_CONVERSION
    #define JSON_DISABLE_TUPLE_REFERENCE_CONVERSION 0
 #endif
+
+#ifndef JSON_DISABLE_STREAM_BULK_SCAN
+    #define JSON_DISABLE_STREAM_BULK_SCAN 0
+#endif
+
+#ifndef JSON_DISABLE_UNLOCKED_FILE_IO
+    #define JSON_DISABLE_UNLOCKED_FILE_IO 0
+#endif
@@ -21,8 +21,9 @@
 #undef JSON_NO_UNIQUE_ADDRESS
 #undef JSON_DISABLE_ENUM_SERIALIZATION
 #undef JSON_DISABLE_TUPLE_REFERENCE_CONVERSION
-#undef JSON_DTOA_SSE2
-#undef JSON_DTOA_NEON
+#undef JSON_DISABLE_STREAM_BULK_SCAN
+#undef JSON_DISABLE_UNLOCKED_FILE_IO
+#undef JSON_UNLOCKED_FILE_IO

 #ifndef JSON_TEST_KEEP_MACROS
    #undef JSON_CATCH
@@ -1366,9 +1366,8 @@ class serializer
    /*!
    @brief dump an integer

-    Dump a given integer, appending it to @ref write_buffer (directly: copying
-    the digits from another buffer right after writing them waits until the
-    stores are done).
+    Dump a given integer, appending it to @ref write_buffer. Works internally with
+    @a number_buffer.

    @param[in] x  integer number (signed or unsigned) to dump
    @tparam NumberType either @a number_integer_t or @a number_unsigned_t
@@ -1403,57 +1402,33 @@ class serializer
            return;
        }

-        // use a pointer to fill the buffer (room for as much as number_buffer holds)
-        if (JSON_HEDLEY_UNLIKELY(write_buffer_pos + number_buffer.size() > write_buffer.size()))
-        {
-            flush();
-        }
-        auto* buffer_ptr = write_buffer.data() + write_buffer_pos;
+        // use a pointer to fill the buffer
+        auto buffer_ptr = number_buffer.begin(); // NOLINT(llvm-qualified-auto,readability-qualified-auto)

        number_unsigned_t abs_value;

-        // one byte for the minus sign
-        unsigned int n_chars = 0;
+        unsigned int n_chars{};

        if (is_negative_number(x))
        {
            *buffer_ptr = '-';
            abs_value = remove_sign(static_cast<number_integer_t>(x));
-            n_chars = 1;
+
+            // account one more byte for the minus sign
+            n_chars = 1 + count_digits(abs_value);
        }
        else
        {
            abs_value = static_cast<number_unsigned_t>(x);
+            n_chars = count_digits(abs_value);
        }

-        // up to 16 digits: eight at a time (as the digits of floats), written
-        // without leading zeros
-        if (abs_value < 10000000000000000u)
-        {
-            const std::uint64_t value = abs_value;
-            const std::uint64_t upper = value / 100000000u;
-            const std::uint64_t first = dtoa_impl::eight_digit_bytes(upper != 0 ? upper : value);
-            const auto leading = static_cast<unsigned>(count_leading_zeros(first) / 8); // (first is not 0)
-            char* const p = buffer_ptr + n_chars;
-            dtoa_impl::store_msb_first(p, (first << (8 * leading)) + 0x3030303030303030u);
-            n_chars += 8 - leading;
-            if (upper != 0)
-            {
-                dtoa_impl::store_msb_first(p + 8 - leading, dtoa_impl::eight_digit_bytes(value - (upper * 100000000u)) + 0x3030303030303030u);
-                n_chars += 8;
-            }
-            write_buffer_pos += n_chars;
-            return;
-        }
-
-        n_chars += count_digits(abs_value);
-
        // spare 1 byte for '\0'
        JSON_ASSERT(n_chars < number_buffer.size() - 1);

        // jump to the end to generate the string from backward,
        // so we later avoid reversing the result
-        buffer_ptr += n_chars;
+        buffer_ptr += static_cast<typename decltype(number_buffer)::difference_type>(n_chars);

        // Fast int2ascii implementation inspired by "Fastware" talk by Andrei Alexandrescu
        // See: https://www.youtube.com/watch?v=o4-CwDo2zpg
@@ -1476,13 +1451,14 @@ class serializer
            *(--buffer_ptr) = static_cast<char>('0' + abs_value);
        }

-        write_buffer_pos += n_chars;
+        put_buffer(number_buffer, n_chars);
    }

    /*!
    @brief dump a floating-point number

-    Dump a given floating-point number, appending it to @ref write_buffer.
+    Dump a given floating-point number, appending it to @ref write_buffer. Works internally
+    with @a number_buffer.

    @param[in] x  floating-point number to dump
    */
@@ -1509,15 +1485,10 @@ class serializer

    void dump_float(number_float_t x, std::true_type /*is_ieee_single_or_double*/)
    {
-        // directly into the write buffer: copying the text from number_buffer
-        // right after to_chars() wrote it waits until its stores are done
-        if (JSON_HEDLEY_UNLIKELY(write_buffer_pos + number_buffer.size() > write_buffer.size()))
-        {
-            flush();
-        }
-        auto* begin = write_buffer.data() + write_buffer_pos;
+        auto* begin = number_buffer.data();
        auto* end = ::nlohmann::detail::to_chars(begin, begin + number_buffer.size(), x);
-        write_buffer_pos += static_cast<std::size_t>(end - begin);
+
+        put_buffer(number_buffer, static_cast<std::size_t>(end - begin));
    }

    JSON_HEDLEY_NON_NULL(1)
@@ -285,6 +285,10 @@ if (JSON_TestSimdutf)
    endif()
 endif()

+# test-file_input checks from a second thread that parsing from a FILE* releases the file's lock
+find_package(Threads REQUIRED)
+json_test_set_test_options("test-file_input;test-file_input_unlocked_io_disabled" LINK_LIBRARIES Threads::Threads)
+
 # *DO* use json_test_set_test_options() above this line

 json_test_should_build_32bit_test(json_32bit_test json_32bit_test_only "${JSON_32bitTest}")
@@ -369,6 +373,33 @@ json_test_add_test_for(src/unit-diagnostic-positions.cpp
    MAIN test_main CXX_STANDARDS ${test_cxx_standards} ${test_force}
 )

+# test reading from a std::istream again without scanning the get area in bulk
+json_test_set_test_options(test-stream-bulk-scan_disabled
+    COMPILE_DEFINITIONS JSON_DISABLE_STREAM_BULK_SCAN=1
+)
+json_test_add_test_for(src/unit-stream-bulk-scan.cpp
+    NAME test-stream-bulk-scan_disabled
+    MAIN test_main CXX_STANDARDS ${test_cxx_standards} ${test_force}
+)
+
+# test reading from a std::istream again with JSON_PRECISE_STREAM_POSITION
+json_test_set_test_options(test-stream-bulk-scan_precise
+    COMPILE_DEFINITIONS JSON_PRECISE_STREAM_POSITION=1
+)
+json_test_add_test_for(src/unit-stream-bulk-scan.cpp
+    NAME test-stream-bulk-scan_precise
+    MAIN test_main CXX_STANDARDS ${test_cxx_standards} ${test_force}
+)
+
+# test reading from a FILE* again with the locking stdio functions
+json_test_set_test_options(test-file_input_unlocked_io_disabled
+    COMPILE_DEFINITIONS JSON_DISABLE_UNLOCKED_FILE_IO=1
+)
+json_test_add_test_for(src/unit-file_input.cpp
+    NAME test-file_input_unlocked_io_disabled
+    MAIN test_main CXX_STANDARDS ${test_cxx_standards} ${test_force}
+)
+
 endif()

 # *DO NOT* use json_test_set_test_options() below this line
@@ -6,9 +6,8 @@ if((CMAKE_CXX_COMPILER_ID MATCHES GNU) OR (CMAKE_CXX_COMPILER_ID MATCHES Clang))
    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -flto -DNDEBUG -O3")
 endif()

-# configure Google Benchmark; a fixed release with a checksum, so that builds are reproducible. Update it like any
-# other dependency; comparisons stay fair because both sides are built with the same version (see README.md)
-set(JSON_GOOGLE_BENCHMARK_VERSION 1.10.0)
+# configure Google Benchmark; a fixed release, so that results stay comparable
+set(JSON_GOOGLE_BENCHMARK_VERSION 1.9.5)
 include(FetchContent)

 # only the library is needed; -Werror would break the pinned release as soon as
@@ -19,7 +18,7 @@ set(BENCHMARK_ENABLE_WERROR OFF CACHE BOOL "" FORCE)

 FetchContent_Declare(benchmark
    URL https://github.com/google/benchmark/archive/refs/tags/v${JSON_GOOGLE_BENCHMARK_VERSION}.tar.gz
-    URL_HASH SHA256=acc5c7c0fbed855c4aaa2d7c3c36fb82b0c15c28f4e151e3f679c2fc0aa404af
+    URL_HASH SHA256=9631341c82bac4a288bef951f8b26b41f69021794184ece969f8473977eaa340
    DOWNLOAD_EXTRACT_TIMESTAMP TRUE
 )
 FetchContent_MakeAvailable(benchmark)
@@ -27,11 +27,8 @@ The input files are those of [nativejson-benchmark](https://github.com/miloyip/n
 - Network access on the first configure: CMake downloads Google Benchmark and the
  [test data](https://github.com/nlohmann/json_test_data) into the build directory. To reuse a download of the test
  data, pass `-DJSON_TestDataDirectory=<build directory>/test_files`.
- Google Benchmark is fetched as a fixed release with a checksum, so that every build uses the same
-  code and a download cannot change under you. It is updated like any other dependency when a new release comes out:
-  change `JSON_GOOGLE_BENCHMARK_VERSION` and the archive's `URL_HASH` in `CMakeLists.txt` together. Results are kept
-  comparable by building both sides of a comparison with the same version, not by keeping that version forever (see
-  [Comparing two versions](#comparing-two-versions)).
+- Google Benchmark is pinned to a release (1.9.5), so that results from different days stay comparable. To update it,
+  change `JSON_GOOGLE_BENCHMARK_VERSION` and the archive's `URL_HASH` in `CMakeLists.txt` together.
 - The benchmarks include `single_include/nlohmann/json.hpp`, so run `make amalgamate` after changing anything in
  `include/`.

@@ -113,18 +110,13 @@ Python, unpinned versions work as well. In its output:
 - `OVERALL_GEOMEAN` summarizes all benchmarks;
 - `-a` shows only the aggregates, not every repetition.

-Both builds use the same Google Benchmark, the one `CMakeLists.txt` names, so only the header differs. For the same
-reason, do not compare against result files from an earlier checkout: a different Google Benchmark, compiler or
-machine state can shift the numbers as much as the change under test. Rerun the baseline instead.
-
 The header you compare with must support everything the benchmarks use. The current benchmarks build against 3.12.0.
 Only benchmarks present in both result files are compared, so for older releases, either filter the benchmarks or
 build that release's own `tests/benchmarks` against its own header.

 ## Getting stable numbers

- Build and run both versions on the same machine with the same compiler and Google Benchmark, one right after the
-  other.
+- Build and run both versions on the same machine, one right after the other.
 - Keep the machine otherwise idle: no builds, no browser, and a laptop plugged in.
 - On Linux, set the CPU frequency governor to `performance`, e.g. `sudo cpupower frequency-set --governor performance`.
  Google Benchmark prints a warning when frequency scaling is enabled. Pinning the process to a core
@@ -8,7 +8,9 @@

 #include <benchmark/benchmark.h>
 #include <nlohmann/json.hpp>
+#include <cstdio>
 #include <fstream>
+#include <sstream>
 #include <numeric>
 #include <vector>
 #include <test_data.hpp>
@@ -48,6 +50,65 @@ BENCHMARK_CAPTURE(ParseFile, signed_ints,       TEST_DATA_DIRECTORY "/regression
 BENCHMARK_CAPTURE(ParseFile, unsigned_ints,     TEST_DATA_DIRECTORY "/regression/unsigned_ints.json");
 BENCHMARK_CAPTURE(ParseFile, small_signed_ints, TEST_DATA_DIRECTORY "/regression/small_signed_ints.json");

+//////////////////////////////////////////////////////////////////////////////
+// parse JSON from a FILE*
+//////////////////////////////////////////////////////////////////////////////
+
+static void ParseFILE(benchmark::State& state, const char* filename)
+{
+    while (state.KeepRunning())
+    {
+        state.PauseTiming();
+        std::FILE* f = std::fopen(filename, "rb");
+        auto* j = new json();
+        state.ResumeTiming();
+
+        *j = json::parse(f);
+
+        state.PauseTiming();
+        std::fclose(f);
+        delete j;
+        state.ResumeTiming();
+    }
+
+    std::ifstream file(filename, std::ios::binary | std::ios::ate);
+    state.SetBytesProcessed(state.iterations() * file.tellg());
+}
+BENCHMARK_CAPTURE(ParseFILE, canada,       TEST_DATA_DIRECTORY "/nativejson-benchmark/canada.json");
+BENCHMARK_CAPTURE(ParseFILE, citm_catalog, TEST_DATA_DIRECTORY "/nativejson-benchmark/citm_catalog.json");
+BENCHMARK_CAPTURE(ParseFILE, twitter,      TEST_DATA_DIRECTORY "/nativejson-benchmark/twitter.json");
+
+//////////////////////////////////////////////////////////////////////////////
+// read many small values from one stream (NDJSON)
+//////////////////////////////////////////////////////////////////////////////
+
+static void ParseStreamValues(benchmark::State& state, bool numbers)
+{
+    std::string input;
+    for (int i = 0; i < 10000; ++i)
+    {
+        input += numbers ? std::to_string(i * 7919) + " "
+                 : R"({"id":)" + std::to_string(i) + R"(,"name":"user)" + std::to_string(i) + R"(","active":true,"score":)" + std::to_string(i * 0.25) + "}\n";
+    }
+
+    for (auto _ : state)
+    {
+        std::istringstream is(input);
+        json j;
+        std::size_t count = 0;
+        while (!(is >> std::ws).eof())
+        {
+            is >> j;
+            ++count;
+        }
+        benchmark::DoNotOptimize(count);
+    }
+
+    state.SetBytesProcessed(static_cast<int64_t>(state.iterations() * input.size()));
+}
+BENCHMARK_CAPTURE(ParseStreamValues, ndjson,  false);
+BENCHMARK_CAPTURE(ParseStreamValues, numbers, true);
+
 //////////////////////////////////////////////////////////////////////////////
 // parse JSON from string
 //////////////////////////////////////////////////////////////////////////////
@@ -1,599 +0,0 @@
-//     __ _____ _____ _____
-//  __|  |   __|     |   | |  JSON for Modern C++ (supporting code)
-// |  |  |__   |  |  | | | |  version 3.12.0
-// |_____|_____|_____|_|___|  https://github.com/nlohmann/json
-//
-// SPDX-FileCopyrightText: 2013-2026 Niels Lohmann <https://nlohmann.me>
-// SPDX-License-Identifier: MIT
-
-#pragma once
-
-#include <array> // array
-#include <cstdint> // uint32_t, uint64_t
-
-// Number tokens that are hard to round correctly, with the IEEE-754 binary64
-// and binary32 bits of their correctly rounded values (ties to even; infinity
-// for an overflow, a signed zero for an underflow).
-//
-// For doubles and floats around 0, the smallest normal number, 1, 2^24, 2^53,
-// 0.1, and the largest finite number, and for random ones, the exact midpoint
-// m to the next number gives: m, m with one unit more and less in the last
-// digit, m with "01" and "0...01" appended, m with trailing zeros, and m cut
-// after 17 to 30 digits (rounded down and up, so that the rounding is decided
-// after the 19th digit), in fixed and exponent notation, 30% of them negative.
-// Tokens longer than 80 characters are left out, except for four of 700 digits
-// and more. Zeros, underflow, overflow, huge exponents, and integers beyond 64
-// bits complete the set. Of the 508 tokens, 134 (as double) and 150 (as
-// float) need the exact comparison with the midpoint (detail::digit_comparison()).
-//
-// The expected bits were computed with exact rational arithmetic in Python
-// (fractions.Fraction) and cross-checked with Python's float(); strtod_l and
-// strtof_l of Apple's libc and of glibc agree. Generated by
-// compact_hard_cases.py 5 (with hard_cases.py), see the pull request that
-// added this file.
-
-namespace float_hard_cases
-{
-
-struct hard_case
-{
-    const char* token;
-    std::uint64_t bits64;
-    std::uint32_t bits32;
-};
-
-inline const std::array<hard_case, 508>& cases()
-{
-    static const std::array<hard_case, 508> table =
-    {
-        {
-            {"-2.4703282292062327e-324", 0x8000000000000000u, 0x80000000u},
-            {"24703282292062328e-340", 0x0000000000000001u, 0x00000000u},
-            {"247032822920623272e-341", 0x0000000000000000u, 0x00000000u},
-            {"-0.2470328229206232721e-323", 0x8000000000000001u, 0x80000000u},
-            {"-0.24703282292062327208e-323", 0x8000000000000000u, 0x80000000u},
-            {"-2.4703282292062327209e-324", 0x8000000000000001u, 0x80000000u},
-            {"2.47032822920623272088e-324", 0x0000000000000000u, 0x00000000u},
-            {"247032822920623272089e-344", 0x0000000000000001u, 0x00000000u},
-            {"-247032822920623272088284396434e-353", 0x8000000000000000u, 0x80000000u},
-            {"0.247032822920623272088284396435e-323", 0x0000000000000001u, 0x00000000u},
-            {"-74109846876186981e-340", 0x8000000000000001u, 0x80000000u},
-            {"0.74109846876186982e-323", 0x0000000000000002u, 0x00000000u},
-            {"-0.7410984687618698162e-323", 0x8000000000000001u, 0x80000000u},
-            {"-7.410984687618698163e-324", 0x8000000000000002u, 0x80000000u},
-            {"7.4109846876186981626e-324", 0x0000000000000001u, 0x00000000u},
-            {"-74109846876186981627e-343", 0x8000000000000002u, 0x80000000u},
-            {"-741098468761869816264e-344", 0x8000000000000001u, 0x80000000u},
-            {"0.741098468761869816265e-323", 0x0000000000000002u, 0x00000000u},
-            {"0.741098468761869816264853189302e-323", 0x0000000000000001u, 0x00000000u},
-            {"-7.41098468761869816264853189303e-324", 0x8000000000000002u, 0x80000000u},
-            {"0.22250738585072006e-307", 0x000FFFFFFFFFFFFEu, 0x00000000u},
-            {"2.2250738585072007e-308", 0x000FFFFFFFFFFFFFu, 0x00000000u},
-            {"2.225073858507200641e-308", 0x000FFFFFFFFFFFFEu, 0x00000000u},
-            {"-2225073858507200642e-326", 0x800FFFFFFFFFFFFFu, 0x80000000u},
-            {"22250738585072006419e-327", 0x000FFFFFFFFFFFFEu, 0x00000000u},
-            {"0.2225073858507200642e-307", 0x000FFFFFFFFFFFFFu, 0x00000000u},
-            {"0.222507385850720064199e-307", 0x000FFFFFFFFFFFFEu, 0x00000000u},
-            {"2.225073858507200642e-308", 0x000FFFFFFFFFFFFFu, 0x00000000u},
-            {"-2.22507385850720064199176395546e-308", 0x800FFFFFFFFFFFFEu, 0x80000000u},
-            {"222507385850720064199176395547e-337", 0x000FFFFFFFFFFFFFu, 0x00000000u},
-            {"-2.2250738585072011e-308", 0x800FFFFFFFFFFFFFu, 0x80000000u},
-            {"-22250738585072012e-324", 0x8010000000000000u, 0x80000000u},
-            {"-2225073858507201136e-326", 0x800FFFFFFFFFFFFFu, 0x80000000u},
-            {"0.2225073858507201137e-307", 0x0010000000000000u, 0x00000000u},
-            {"0.2225073858507201136e-307", 0x000FFFFFFFFFFFFFu, 0x00000000u},
-            {"-2.2250738585072011361e-308", 0x8010000000000000u, 0x80000000u},
-            {"2.22507385850720113605e-308", 0x000FFFFFFFFFFFFFu, 0x00000000u},
-            {"222507385850720113606e-328", 0x0010000000000000u, 0x00000000u},
-            {"22250738585072011360574097967e-336", 0x000FFFFFFFFFFFFFu, 0x00000000u},
-            {"0.222507385850720113605740979671e-307", 0x0010000000000000u, 0x00000000u},
-            {"22250738585072016e-324", 0x0010000000000000u, 0x00000000u},
-            {"0.22250738585072017e-307", 0x0010000000000001u, 0x00000000u},
-            {"0.222507385850720163e-307", 0x0010000000000000u, 0x00000000u},
-            {"2.225073858507201631e-308", 0x0010000000000001u, 0x00000000u},
-            {"-2.2250738585072016301e-308", 0x8010000000000000u, 0x80000000u},
-            {"22250738585072016302e-327", 0x0010000000000001u, 0x00000000u},
-            {"-222507385850720163012e-328", 0x8010000000000000u, 0x80000000u},
-            {"0.222507385850720163013e-307", 0x0010000000000001u, 0x00000000u},
-            {"0.222507385850720163012305563795e-307", 0x0010000000000000u, 0x00000000u},
-            {"-2.22507385850720163012305563796e-308", 0x8010000000000001u, 0x80000000u},
-            {"0.17976931348623156E+309", 0x7FEFFFFFFFFFFFFEu, 0x7F800000u},
-            {"1.7976931348623157e308", 0x7FEFFFFFFFFFFFFFu, 0x7F800000u},
-            {"1.797693134862315608e308", 0x7FEFFFFFFFFFFFFEu, 0x7F800000u},
-            {"-1797693134862315609e290", 0xFFEFFFFFFFFFFFFFu, 0xFF800000u},
-            {"-17976931348623156083e289", 0xFFEFFFFFFFFFFFFEu, 0xFF800000u},
-            {"-0.17976931348623156084E+309", 0xFFEFFFFFFFFFFFFFu, 0xFF800000u},
-            {"0.179769313486231560835E+309", 0x7FEFFFFFFFFFFFFEu, 0x7F800000u},
-            {"-1.79769313486231560836e308", 0xFFEFFFFFFFFFFFFFu, 0xFF800000u},
-            {"1.79769313486231560835325876058e308", 0x7FEFFFFFFFFFFFFEu, 0x7F800000u},
-            {"179769313486231560835325876059e279", 0x7FEFFFFFFFFFFFFFu, 0x7F800000u},
-            {"1.7976931348623158e308", 0x7FEFFFFFFFFFFFFFu, 0x7F800000u},
-            {"17976931348623159e292", 0x7FF0000000000000u, 0x7F800000u},
-            {"1797693134862315807e290", 0x7FEFFFFFFFFFFFFFu, 0x7F800000u},
-            {"0.1797693134862315808E+309", 0x7FF0000000000000u, 0x7F800000u},
-            {"0.17976931348623158079E+309", 0x7FEFFFFFFFFFFFFFu, 0x7F800000u},
-            {"-1.797693134862315808e308", 0xFFF0000000000000u, 0xFF800000u},
-            {"1.79769313486231580793e308", 0x7FEFFFFFFFFFFFFFu, 0x7F800000u},
-            {"179769313486231580794e288", 0x7FF0000000000000u, 0x7F800000u},
-            {"179769313486231580793728971405e279", 0x7FEFFFFFFFFFFFFFu, 0x7F800000u},
-            {"-0.179769313486231580793728971406E+309", 0xFFF0000000000000u, 0xFF800000u},
-            {"100000000000000011102230246251565404236316680908203125e-53", 0x3FF0000000000000u, 0x3F800000u},
-            {"-1.00000000000000011102230246251565404236316680908203126", 0xBFF0000000000001u, 0xBF800000u},
-            {"1.00000000000000011102230246251565404236316680908203124e0", 0x3FF0000000000000u, 0x3F800000u},
-            {"10000000000000001110223024625156540423631668090820312501e-55", 0x3FF0000000000001u, 0x3F800000u},
-            {"1.00000000000000011102230246251565404236316680908203125000000000000000000001", 0x3FF0000000000001u, 0x3F800000u},
-            {"10000000000000001e-16", 0x3FF0000000000000u, 0x3F800000u},
-            {"1.0000000000000002", 0x3FF0000000000001u, 0x3F800000u},
-            {"1.000000000000000111", 0x3FF0000000000000u, 0x3F800000u},
-            {"1.000000000000000112e0", 0x3FF0000000000001u, 0x3F800000u},
-            {"1.000000000000000111e0", 0x3FF0000000000000u, 0x3F800000u},
-            {"-10000000000000001111e-19", 0xBFF0000000000001u, 0xBF800000u},
-            {"-100000000000000011102e-20", 0xBFF0000000000000u, 0xBF800000u},
-            {"-1.00000000000000011103", 0xBFF0000000000001u, 0xBF800000u},
-            {"1.00000000000000011102230246251", 0x3FF0000000000000u, 0x3F800000u},
-            {"1.00000000000000011102230246252e0", 0x3FF0000000000001u, 0x3F800000u},
-            {"-0.999999999999999944488848768742172978818416595458984375", 0xBFF0000000000000u, 0xBF800000u},
-            {"-9.99999999999999944488848768742172978818416595458984376e-1", 0xBFF0000000000000u, 0xBF800000u},
-            {"999999999999999944488848768742172978818416595458984374e-54", 0x3FEFFFFFFFFFFFFFu, 0x3F800000u},
-            {"0.99999999999999994448884876874217297881841659545898437501", 0x3FF0000000000000u, 0x3F800000u},
-            {"9.99999999999999944488848768742172978818416595458984375000000000000000000001e-1", 0x3FF0000000000000u, 0x3F800000u},
-            {"-0.99999999999999994", 0xBFEFFFFFFFFFFFFFu, 0xBF800000u},
-            {"9.9999999999999995e-1", 0x3FF0000000000000u, 0x3F800000u},
-            {"9.999999999999999444e-1", 0x3FEFFFFFFFFFFFFFu, 0x3F800000u},
-            {"9999999999999999445e-19", 0x3FF0000000000000u, 0x3F800000u},
-            {"99999999999999994448e-20", 0x3FEFFFFFFFFFFFFFu, 0x3F800000u},
-            {"-0.99999999999999994449", 0xBFF0000000000000u, 0xBF800000u},
-            {"0.999999999999999944488", 0x3FEFFFFFFFFFFFFFu, 0x3F800000u},
-            {"-9.99999999999999944489e-1", 0xBFF0000000000000u, 0xBF800000u},
-            {"9.99999999999999944488848768742e-1", 0x3FEFFFFFFFFFFFFFu, 0x3F800000u},
-            {"999999999999999944488848768743e-30", 0x3FF0000000000000u, 0x3F800000u},
-            {"-9.007199254740993e15", 0xC340000000000000u, 0xDA000000u},
-            {"9007199254740994e0", 0x4340000000000001u, 0x5A000000u},
-            {"9007199254740992", 0x4340000000000000u, 0x5A000000u},
-            {"9.00719925474099301e15", 0x4340000000000001u, 0x5A000000u},
-            {"9007199254740993000000000000000000001e-21", 0x4340000000000001u, 0x5A000000u},
-            {"-9007199254740993.000000000000000000000000000000", 0xC340000000000000u, 0xDA000000u},
-            {"90071992547409915e-1", 0x4340000000000000u, 0x5A000000u},
-            {"-9007199254740991.6", 0xC340000000000000u, 0xDA000000u},
-            {"9.0071992547409914e15", 0x433FFFFFFFFFFFFFu, 0x5A000000u},
-            {"-9007199254740991501e-3", 0xC340000000000000u, 0xDA000000u},
-            {"9007199254740991.5000000000000000000001", 0x4340000000000000u, 0x5A000000u},
-            {"9.0071992547409915000000000000000000000000000000e15", 0x4340000000000000u, 0x5A000000u},
-            {"0.100000000000000012490009027033011079765856266021728515625", 0x3FB999999999999Au, 0x3DCCCCCDu},
-            {"1.00000000000000012490009027033011079765856266021728515626e-1", 0x3FB999999999999Bu, 0x3DCCCCCDu},
-            {"100000000000000012490009027033011079765856266021728515624e-57", 0x3FB999999999999Au, 0x3DCCCCCDu},
-            {"0.10000000000000001249000902703301107976585626602172851562501", 0x3FB999999999999Bu, 0x3DCCCCCDu},
-            {"0.10000000000000001", 0x3FB999999999999Au, 0x3DCCCCCDu},
-            {"1.0000000000000002e-1", 0x3FB999999999999Bu, 0x3DCCCCCDu},
-            {"-1.000000000000000124e-1", 0xBFB999999999999Au, 0xBDCCCCCDu},
-            {"1000000000000000125e-19", 0x3FB999999999999Bu, 0x3DCCCCCDu},
-            {"-10000000000000001249e-20", 0xBFB999999999999Au, 0xBDCCCCCDu},
-            {"0.1000000000000000125", 0x3FB999999999999Bu, 0x3DCCCCCDu},
-            {"0.10000000000000001249", 0x3FB999999999999Au, 0x3DCCCCCDu},
-            {"1.00000000000000012491e-1", 0x3FB999999999999Bu, 0x3DCCCCCDu},
-            {"1.00000000000000012490009027033e-1", 0x3FB999999999999Au, 0x3DCCCCCDu},
-            {"100000000000000012490009027034e-30", 0x3FB999999999999Bu, 0x3DCCCCCDu},
-            {"2.45134755833537796875e14", 0x42EBDE5C4164D83Au, 0x575EF2E2u},
-            {"-245134755833537796876e-6", 0xC2EBDE5C4164D83Au, 0xD75EF2E2u},
-            {"-245134755833537.796874", 0xC2EBDE5C4164D839u, 0xD75EF2E2u},
-            {"2.4513475583353779687501e14", 0x42EBDE5C4164D83Au, 0x575EF2E2u},
-            {"245134755833537796875000000000000000000001e-27", 0x42EBDE5C4164D83Au, 0x575EF2E2u},
-            {"245134755833537.796875000000000000000000000000000000", 0x42EBDE5C4164D83Au, 0x575EF2E2u},
-            {"2.4513475583353779e14", 0x42EBDE5C4164D839u, 0x575EF2E2u},
-            {"2451347558335378e-1", 0x42EBDE5C4164D83Au, 0x575EF2E2u},
-            {"2451347558335377968e-4", 0x42EBDE5C4164D839u, 0x575EF2E2u},
-            {"245134755833537.7969", 0x42EBDE5C4164D83Au, 0x575EF2E2u},
-            {"245134755833537.79687", 0x42EBDE5C4164D839u, 0x575EF2E2u},
-            {"2.4513475583353779688e14", 0x42EBDE5C4164D83Au, 0x575EF2E2u},
-            {"181510327827821147441864013671875e-23", 0x41DB0C11CB91CE38u, 0x4ED8608Eu},
-            {"-1815103278.27821147441864013671876", 0xC1DB0C11CB91CE38u, 0xCED8608Eu},
-            {"1.81510327827821147441864013671874e9", 0x41DB0C11CB91CE37u, 0x4ED8608Eu},
-            {"18151032782782114744186401367187501e-25", 0x41DB0C11CB91CE38u, 0x4ED8608Eu},
-            {"1815103278.27821147441864013671875000000000000000000001", 0x41DB0C11CB91CE38u, 0x4ED8608Eu},
-            {"-1.81510327827821147441864013671875000000000000000000000000000000e9", 0xC1DB0C11CB91CE38u, 0xCED8608Eu},
-            {"18151032782782114e-7", 0x41DB0C11CB91CE37u, 0x4ED8608Eu},
-            {"1815103278.2782115", 0x41DB0C11CB91CE38u, 0x4ED8608Eu},
-            {"1815103278.278211474", 0x41DB0C11CB91CE37u, 0x4ED8608Eu},
-            {"-1.815103278278211475e9", 0xC1DB0C11CB91CE38u, 0xCED8608Eu},
-            {"1.8151032782782114744e9", 0x41DB0C11CB91CE37u, 0x4ED8608Eu},
-            {"-18151032782782114745e-10", 0xC1DB0C11CB91CE38u, 0xCED8608Eu},
-            {"181510327827821147441e-11", 0x41DB0C11CB91CE37u, 0x4ED8608Eu},
-            {"1815103278.27821147442", 0x41DB0C11CB91CE38u, 0x4ED8608Eu},
-            {"1815103278.27821147441864013671", 0x41DB0C11CB91CE37u, 0x4ED8608Eu},
-            {"1.81510327827821147441864013672e9", 0x41DB0C11CB91CE38u, 0x4ED8608Eu},
-            {"3809325632181785344", 0x43CA6EB8BD69FE2Au, 0x5E5375C6u},
-            {"3.809325632181785345e18", 0x43CA6EB8BD69FE2Au, 0x5E5375C6u},
-            {"3809325632181785343e0", 0x43CA6EB8BD69FE29u, 0x5E5375C6u},
-            {"3809325632181785344.01", 0x43CA6EB8BD69FE2Au, 0x5E5375C6u},
-            {"3.809325632181785344000000000000000000001e18", 0x43CA6EB8BD69FE2Au, 0x5E5375C6u},
-            {"3809325632181785344000000000000000000000000000000e-30", 0x43CA6EB8BD69FE2Au, 0x5E5375C6u},
-            {"3809325632181785300", 0x43CA6EB8BD69FE29u, 0x5E5375C6u},
-            {"3.8093256321817854e18", 0x43CA6EB8BD69FE2Au, 0x5E5375C6u},
-            {"4.046966549916366943359375e12", 0x428D7210076CE2F0u, 0x546B9080u},
-            {"4046966549916366943359376e-12", 0x428D7210076CE2F0u, 0x546B9080u},
-            {"4046966549916.366943359374", 0x428D7210076CE2EFu, 0x546B9080u},
-            {"4.04696654991636694335937501e12", 0x428D7210076CE2F0u, 0x546B9080u},
-            {"4046966549916366943359375000000000000000000001e-33", 0x428D7210076CE2F0u, 0x546B9080u},
-            {"-4046966549916.366943359375000000000000000000000000000000", 0xC28D7210076CE2F0u, 0xD46B9080u},
-            {"4.0469665499163669e12", 0x428D7210076CE2EFu, 0x546B9080u},
-            {"4046966549916367e-3", 0x428D7210076CE2F0u, 0x546B9080u},
-            {"4046966549916366943e-6", 0x428D7210076CE2EFu, 0x546B9080u},
-            {"4046966549916.366944", 0x428D7210076CE2F0u, 0x546B9080u},
-            {"4046966549916.3669433", 0x428D7210076CE2EFu, 0x546B9080u},
-            {"4.0469665499163669434e12", 0x428D7210076CE2F0u, 0x546B9080u},
-            {"-4.04696654991636694335e12", 0xC28D7210076CE2EFu, 0xD46B9080u},
-            {"404696654991636694336e-8", 0x428D7210076CE2F0u, 0x546B9080u},
-            {"28093802557000874e154", 0x63529C3B77330BDBu, 0x7F800000u},
-            {"0.28093802557000875E+171", 0x63529C3B77330BDCu, 0x7F800000u},
-            {"0.2809380255700087447E+171", 0x63529C3B77330BDBu, 0x7F800000u},
-            {"2.809380255700087448e170", 0x63529C3B77330BDCu, 0x7F800000u},
-            {"2.8093802557000874472e170", 0x63529C3B77330BDBu, 0x7F800000u},
-            {"28093802557000874473e151", 0x63529C3B77330BDCu, 0x7F800000u},
-            {"280938025570008744728e150", 0x63529C3B77330BDBu, 0x7F800000u},
-            {"-0.280938025570008744729E+171", 0xE3529C3B77330BDCu, 0xFF800000u},
-            {"-0.280938025570008744728403667979E+171", 0xE3529C3B77330BDBu, 0xFF800000u},
-            {"2.8093802557000874472840366798e170", 0x63529C3B77330BDCu, 0x7F800000u},
-            {"0.39523280297734525e-154", 0x1FE0F51BF17FD374u, 0x00000000u},
-            {"-3.9523280297734526e-155", 0x9FE0F51BF17FD375u, 0x80000000u},
-            {"3.952328029773452547e-155", 0x1FE0F51BF17FD374u, 0x00000000u},
-            {"3952328029773452548e-173", 0x1FE0F51BF17FD375u, 0x00000000u},
-            {"-39523280297734525478e-174", 0x9FE0F51BF17FD374u, 0x80000000u},
-            {"0.39523280297734525479e-154", 0x1FE0F51BF17FD375u, 0x00000000u},
-            {"-0.395232802977345254787e-154", 0x9FE0F51BF17FD374u, 0x80000000u},
-            {"-3.95232802977345254788e-155", 0x9FE0F51BF17FD375u, 0x80000000u},
-            {"-3.95232802977345254787245825501e-155", 0x9FE0F51BF17FD374u, 0x80000000u},
-            {"395232802977345254787245825502e-184", 0x1FE0F51BF17FD375u, 0x00000000u},
-            {"-1.0790205420931879e-276", 0x86A3209CA6233255u, 0x80000000u},
-            {"-1079020542093188e-291", 0x86A3209CA6233256u, 0x80000000u},
-            {"-1079020542093187947e-294", 0x86A3209CA6233255u, 0x80000000u},
-            {"0.1079020542093187948e-275", 0x06A3209CA6233256u, 0x00000000u},
-            {"0.1079020542093187947e-275", 0x06A3209CA6233255u, 0x00000000u},
-            {"1.0790205420931879471e-276", 0x06A3209CA6233256u, 0x00000000u},
-            {"1.07902054209318794701e-276", 0x06A3209CA6233255u, 0x00000000u},
-            {"-107902054209318794702e-296", 0x86A3209CA6233256u, 0x80000000u},
-            {"107902054209318794701153285302e-305", 0x06A3209CA6233255u, 0x00000000u},
-            {"-0.107902054209318794701153285303e-275", 0x86A3209CA6233256u, 0x80000000u},
-            {"58530471071351308e-228", 0x1413B446E6A16A3Bu, 0x00000000u},
-            {"-0.58530471071351309e-211", 0x9413B446E6A16A3Cu, 0x80000000u},
-            {"0.5853047107135130893e-211", 0x1413B446E6A16A3Bu, 0x00000000u},
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-            {"-6.5650615096092224121e-1", 0xBFE5021930000000u, 0xBF2810C9u},
-            {"656506150960922241211e-21", 0x3FE5021930000000u, 0x3F2810CAu},
-            {"18014627239033005156980393746124491372029297053813934326171875e-77", 0x3CA9F63970000000u, 0x254FB1CCu},
-            {"0.00000000000000018014627239033005156980393746124491372029297053813934326171876", 0x3CA9F63970000000u, 0x254FB1CCu},
-            {"-1.8014627239033005156980393746124491372029297053813934326171874e-16", 0xBCA9F63970000000u, 0xA54FB1CBu},
-            {"1801462723903300515698039374612449137202929705381393432617187501e-79", 0x3CA9F63970000000u, 0x254FB1CCu},
-            {"18014627239033005e-32", 0x3CA9F63970000000u, 0x254FB1CBu},
-            {"0.00000000000000018014627239033006", 0x3CA9F63970000000u, 0x254FB1CCu},
-            {"0.0000000000000001801462723903300515", 0x3CA9F63970000000u, 0x254FB1CBu},
-            {"-1.801462723903300516e-16", 0xBCA9F63970000000u, 0xA54FB1CCu},
-            {"-1.8014627239033005156e-16", 0xBCA9F63970000000u, 0xA54FB1CBu},
-            {"18014627239033005157e-35", 0x3CA9F63970000000u, 0x254FB1CCu},
-            {"180146272390330051569e-36", 0x3CA9F63970000000u, 0x254FB1CBu},
-            {"-0.00000000000000018014627239033005157", 0xBCA9F63970000000u, 0xA54FB1CCu},
-            {"0.000000000000000180146272390330051569803937461", 0x3CA9F63970000000u, 0x254FB1CBu},
-            {"1.80146272390330051569803937462e-16", 0x3CA9F63970000000u, 0x254FB1CCu},
-            {"0.05534819327294826507568359375", 0x3FAC569930000000u, 0x3D62B4CAu},
-            {"-5.534819327294826507568359376e-2", 0xBFAC569930000000u, 0xBD62B4CAu},
-            {"5534819327294826507568359374e-29", 0x3FAC569930000000u, 0x3D62B4C9u},
-            {"-0.0553481932729482650756835937501", 0xBFAC569930000000u, 0xBD62B4CAu},
-            {"5.534819327294826507568359375000000000000000000001e-2", 0x3FAC569930000000u, 0x3D62B4CAu},
-            {"5534819327294826507568359375000000000000000000000000000000e-59", 0x3FAC569930000000u, 0x3D62B4CAu},
-            {"0.055348193272948265", 0x3FAC569930000000u, 0x3D62B4C9u},
-            {"5.5348193272948266e-2", 0x3FAC569930000000u, 0x3D62B4CAu},
-            {"5.534819327294826507e-2", 0x3FAC569930000000u, 0x3D62B4C9u},
-            {"5534819327294826508e-20", 0x3FAC569930000000u, 0x3D62B4CAu},
-            {"55348193272948265075e-21", 0x3FAC569930000000u, 0x3D62B4C9u},
-            {"-0.055348193272948265076", 0xBFAC569930000000u, 0xBD62B4CAu},
-            {"0.0553481932729482650756", 0x3FAC569930000000u, 0x3D62B4C9u},
-            {"-5.53481932729482650757e-2", 0xBFAC569930000000u, 0xBD62B4CAu},
-            {"5.179692133247783258005389047985340416e36", 0x478F2C9450000000u, 0x7C7964A2u},
-            {"5179692133247783258005389047985340417e0", 0x478F2C9450000000u, 0x7C7964A3u},
-            {"5179692133247783258005389047985340415", 0x478F2C9450000000u, 0x7C7964A2u},
-            {"-5.17969213324778325800538904798534041601e36", 0xC78F2C9450000000u, 0xFC7964A3u},
-            {"-5179692133247783258005389047985340416000000000000000000001e-21", 0xC78F2C9450000000u, 0xFC7964A3u},
-            {"-5179692133247783258005389047985340416.000000000000000000000000000000", 0xC78F2C9450000000u, 0xFC7964A2u},
-            {"5.1796921332477832e36", 0x478F2C9450000000u, 0x7C7964A2u},
-            {"51796921332477833e20", 0x478F2C9450000000u, 0x7C7964A3u},
-            {"-5179692133247783258e18", 0xC78F2C9450000000u, 0xFC7964A2u},
-            {"5179692133247783259000000000000000000", 0x478F2C9450000000u, 0x7C7964A3u},
-            {"5179692133247783258000000000000000000", 0x478F2C9450000000u, 0x7C7964A2u},
-            {"5.1796921332477832581e36", 0x478F2C9450000000u, 0x7C7964A3u},
-            {"-5.179692133247783258e36", 0xC78F2C9450000000u, 0xFC7964A2u},
-            {"-517969213324778325801e16", 0xC78F2C9450000000u, 0xFC7964A3u},
-            {"517969213324778325800538904798e7", 0x478F2C9450000000u, 0x7C7964A2u},
-            {"5179692133247783258005389047990000000", 0x478F2C9450000000u, 0x7C7964A3u},
-            {
-                "0.22250738585072011360574097967091319759348195463516456480234261097248222220210769455165295239081350"
-                "8791414915891303962110687008643869459464552765720740782062174337998814106326732925355228688137214901"
-                "2981122451451889849057222307285255133155755015914397476397983411801999323962548289017107081850690630"
-                "6666559949382757725720157630626906633326475653000092458883164330377797918696120494973903778297049050"
-                "5108060994073026293712895895000358379996720725430436028407889577179615094551674824347103070260914462"
-                "1572289880258182545180325707018860872113128079512233426288368622321503775666622503982534335974568884"
-                "4239002654981983854879482922068947216898310996983658468140228542433306603398508864458040010349339704"
-                "2756718644338377048603786162277173854562306587467901408672332763671875e-307", 0x0010000000000000u, 0x00000000u
-            },
-            {
-                "2.22507385850720113605740979670913197593481954635164564802342610972482222202107694551652952390813508"
-                "7914149158913039621106870086438694594645527657207407820621743379988141063267329253552286881372149012"
-                "9811224514518898490572223072852551331557550159143974763979834118019993239625482890171070818506906306"
-                "6665599493827577257201576306269066333264756530000924588831643303777979186961204949739037782970490505"
-                "1080609940730262937128958950003583799967207254304360284078895771796150945516748243471030702609144621"
-                "5722898802581825451803257070188608721131280795122334262883686223215037756666225039825343359745688844"
-                "2390026549819838548794829220689472168983109969836584681402285424333066033985088644580400103493397042"
-                "756718644338377048603786162277173854562306587467901408672332763671875000000000000000000001e-308", 0x0010000000000000u, 0x00000000u
-            },
-            {
-                "0.11754942807573642917278829910357665133228589927589904276829631184250030649651730385585324256680905"
-                "8189392089843750000000000000000000000000000000000000000000000000000000000000000000000000000000000000"
-                "0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000"
-                "0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000"
-                "0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000"
-                "0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000"
-                "0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000"
-                "00000000000000000000000000000000000000000000000000000000000000000e-37", 0x380FFFFFE0000000u, 0x00800000u
-            },
-            {
-                "1175494280757364291727882991035766513322858992758990427682963118425003064965173038558532425668090581"
-                "8939208984375000000000000000000000000000000000000000000000000000000000000000000000000000000000000000"
-                "0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000"
-                "0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000"
-                "0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000"
-                "0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000"
-                "0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000"
-                "00000000000001e-751", 0x380FFFFFE0000000u, 0x00800000u
-            },
-            {"0", 0x0000000000000000u, 0x00000000u},
-            {"-0", 0x8000000000000000u, 0x80000000u},
-            {"0.0", 0x0000000000000000u, 0x00000000u},
-            {"-0.0", 0x8000000000000000u, 0x80000000u},
-            {"0e999999999999999999999", 0x0000000000000000u, 0x00000000u},
-            {"-0.000e-99999", 0x8000000000000000u, 0x80000000u},
-            {"1e-400", 0x0000000000000000u, 0x00000000u},
-            {"-1e-400", 0x8000000000000000u, 0x80000000u},
-            {"1e400", 0x7FF0000000000000u, 0x7F800000u},
-            {"-1e400", 0xFFF0000000000000u, 0xFF800000u},
-            {"1e-50", 0x358DEE7A4AD4B81Fu, 0x00000000u},
-            {"-1e-50", 0xB58DEE7A4AD4B81Fu, 0x80000000u},
-            {"1e39", 0x48078287F49C4A1Du, 0x7F800000u},
-            {"-1e39", 0xC8078287F49C4A1Du, 0xFF800000u},
-            {"1e99999999999999999999999999", 0x7FF0000000000000u, 0x7F800000u},
-            {"1e-99999999999999999999999999", 0x0000000000000000u, 0x00000000u},
-            {"1e0000000000000000000000000000000000000000308", 0x7FE1CCF385EBC8A0u, 0x7F800000u},
-            {"123456789012345678901234567890e-30", 0x3FBF9ADD3746F65Fu, 0x3DFCD6EAu},
-            {"18446744073709551615", 0x43F0000000000000u, 0x5F800000u},
-            {"18446744073709551616", 0x43F0000000000000u, 0x5F800000u},
-            {"-9223372036854775808", 0xC3E0000000000000u, 0xDF000000u},
-            {"-9223372036854775809", 0xC3E0000000000000u, 0xDF000000u},
-        }
-    };
-    return table;
-}
-
-} // namespace float_hard_cases
@@ -38,7 +38,7 @@ TEST_CASE("Binary Formats")
        const auto ubjson_2_size = json::to_ubjson(j, true).size();
        const auto ubjson_3_size = json::to_ubjson(j, true, true).size();

-        CHECK(json_size == 2090234);
+        CHECK(json_size == 2090303);
        CHECK(bjdata_1_size == 1112030);
        CHECK(bjdata_2_size == 1224148);
        CHECK(bjdata_3_size == 1224148);
@@ -51,16 +51,16 @@ TEST_CASE("Binary Formats")
        CHECK(ubjson_3_size == 1169069);

        CHECK((100.0 * double(json_size) / double(json_size)) == Approx(100.0));
-        CHECK((100.0 * double(bjdata_1_size) / double(json_size)) == Approx(53.201));
-        CHECK((100.0 * double(bjdata_2_size) / double(json_size)) == Approx(58.565));
-        CHECK((100.0 * double(bjdata_3_size) / double(json_size)) == Approx(58.565));
-        CHECK((100.0 * double(bon8_size) / double(json_size)) == Approx(50.511));
-        CHECK((100.0 * double(bson_size) / double(json_size)) == Approx(85.853));
-        CHECK((100.0 * double(cbor_size) / double(json_size)) == Approx(50.499));
-        CHECK((100.0 * double(msgpack_size) / double(json_size)) == Approx(50.528));
-        CHECK((100.0 * double(ubjson_1_size) / double(json_size)) == Approx(53.201));
-        CHECK((100.0 * double(ubjson_2_size) / double(json_size)) == Approx(58.565));
-        CHECK((100.0 * double(ubjson_3_size) / double(json_size)) == Approx(55.930));
+        CHECK((100.0 * double(bjdata_1_size) / double(json_size)) == Approx(53.199));
+        CHECK((100.0 * double(bjdata_2_size) / double(json_size)) == Approx(58.563));
+        CHECK((100.0 * double(bjdata_3_size) / double(json_size)) == Approx(58.563));
+        CHECK((100.0 * double(bon8_size) / double(json_size)) == Approx(50.509));
+        CHECK((100.0 * double(bson_size) / double(json_size)) == Approx(85.849));
+        CHECK((100.0 * double(cbor_size) / double(json_size)) == Approx(50.497));
+        CHECK((100.0 * double(msgpack_size) / double(json_size)) == Approx(50.526));
+        CHECK((100.0 * double(ubjson_1_size) / double(json_size)) == Approx(53.199));
+        CHECK((100.0 * double(ubjson_2_size) / double(json_size)) == Approx(58.563));
+        CHECK((100.0 * double(ubjson_3_size) / double(json_size)) == Approx(55.928));
    }

    SECTION("twitter.json")
@@ -13,20 +13,16 @@
 using nlohmann::json;

 #include <array> // array
+#include <cfloat> // FLT_EVAL_METHOD
 #include <cstdint> // uint32_t, uint64_t
-#include <cstdio> // snprintf
 #include <cstdlib> // strtod
 #include <cstring> // memcpy
 #include <limits> // numeric_limits
-#include <map> // map
-#include <random> // mt19937
 #include <sstream> // stringstream
 #include <string> // string
 #include <utility> // pair
 #include <vector> // vector

-#include "float_hard_cases.hpp"
-
 namespace
 {
 // shortcut to scan a string literal
@@ -262,7 +258,7 @@ TEST_CASE("lexer number fast path")
            "123456789012345678901234567890",  // huge -> float
            "0.30000000000000004", "2.2250738585072014e-308", "1e308",
            // high-precision / wide-exponent values that exercise the
-            // Eisel-Lemire path beyond the Clinger subset
+            // std::from_chars (Eisel-Lemire) path beyond the Clinger subset
            "1.7976931348623157e308", "1.2345678901234567e-250",
            "9007199254740993", "5e-324", "1e-320"
        };
@@ -284,18 +280,20 @@ TEST_CASE("lexer number fast path")
        }
    }

-    SECTION("significant digits around Clinger's fast path")
+    SECTION("significant-digit gate for the Clinger fast path")
    {
-        // Clinger's fast path needs a significand of at most 2^53, which
-        // tokens with 17 or more significant digits exceed. The conversion
-        // splits the token at the positions the scanners recorded, so leading
-        // zeros must not count as digits - "0.1234567890123456" has 16
-        // significant digits, not 17 - and both scanners must agree.
+        // Clinger's fast path needs a significand below 2^53, so it cannot
+        // succeed once the mantissa has 17 or more significant digits (the
+        // significand would be at least 10^16). The lexer skips the attempt
+        // there. That is only allowed to save work: every value must still come
+        // out bit-exactly, and both scanners must agree. In particular the gate
+        // must not fire for tokens whose leading zeros merely look like extra
+        // digits - "0.1234567890123456" has 16 significant digits, not 17.
        const std::vector<std::string> numbers =
        {
            "1234567890123456",                  // 16 significant digits
-            "12345678901234567",                 // 17
-            "123456789012345678",                // 18
+            "12345678901234567",                 // 17 -> attempt skipped
+            "123456789012345678",                // 18 -> attempt skipped
            "0.1234567890123456",                // 16: the leading "0" is not significant
            "0.12345678901234567",               // 17
            "0.00000000000000001",               // 1, in a long token
@@ -666,323 +664,46 @@ TEST_CASE("lexer string fast path")
    }
 }

-TEST_CASE("lexer escape fast path")
+TEST_CASE("parse_float_fast declines what it cannot convert exactly")
 {
-    // json::accept() never throws, so this section stays covered without
-    // exceptions; it pins which of the cases below are valid/invalid and
-    // checks the contiguous and streaming paths agree on that classification.
-    SECTION("accept() parity")
+    // The lexer only hands well-formed numbers to parse_float_fast, so the
+    // malformed ones below can only be passed to it directly. Declining is
+    // always safe: the caller then falls back to a slower, exact conversion.
+    const auto fast = [](const std::string & s, double & out)
    {
-        const std::vector<std::pair<std::string, bool>> cases =
-        {
-            {"\\u0041", true}, {"\\u00e4", true}, {"\\u00E4", true},
-            {"\\uD83D\\uDE00", true},
-            {"\\u12", false}, {"\\u12G4", false}, {"\\uXYZW", false},
-            {"\\uD800", false}, {"\\uD800A", false}, {"\\uD800\\u0041", false},
-            {"\\uDC00", false}, {"\\u", false}
-        };
-
-        for (const auto& c : cases)
-        {
-            for (const std::size_t offset :
-                    {
-                        std::size_t{0}, std::size_t{9}
-                    })
-            {
-                const std::string doc = "[\"" + std::string(offset, 'a') + c.first + "\"]";
-                CAPTURE(doc)
-                CHECK(json::accept(doc) == c.second);
-                std::stringstream ss(doc);
-                CHECK(json::accept(ss) == c.second);
-            }
-        }
-    }
-
-#if !defined(JSON_NOEXCEPTION)
-    // the full outcome of parsing @a doc: the parsed value, or the exact
-    // error message, so a mismatch in either is caught
-    const auto outcome = [](const std::string & doc, bool streaming) -> std::string
-    {
-        try
-        {
-            if (streaming)
-            {
-                std::stringstream ss(doc);
-                const json j = json::parse(ss);
-                return j.dump();
-            }
-            const json j = json::parse(doc);
-            return j.dump();
-        }
-        catch (const json::exception& e)
-        {
-            return {e.what()};
-        }
+        return nlohmann::detail::parse_float_fast(s.data(), s.data() + s.size(), out);
    };
+    double out = 0;

-    SECTION("contiguous vs streaming parity")
-    {
-        const std::vector<std::string> escapes =
-        {
-            "\\u0041",             // "A"
-            "\\u00e4",             // "ä" (lowercase hex)
-            "\\u00E4",             // "ä" (uppercase hex)
-            "\\uD83D\\uDE00",      // valid surrogate pair (an emoji)
-            "\\u12",               // truncated: only 2 hex digits before the closing quote
-            "\\u12G4",             // invalid hex digit at the 3rd position
-            "\\uXYZW",             // all 4 bytes invalid
-            "\\uD800",             // lone high surrogate, string ends right after
-            "\\uD800A",            // high surrogate not followed by another \u escape
-            "\\uD800\\u0041",      // high surrogate followed by \u, but not a low surrogate
-            "\\uDC00",             // lone low surrogate
-            "\\u",                 // '\u' with nothing after (closing quote right away)
-        };
-
-        // once at the start of the string and once past the first 8-byte SWAR
-        // word of the outer string_bulk_run, so the escape is reached both
-        // right after the opening quote and mid-run
-        for (const auto& escape : escapes)
-        {
-            for (const std::size_t offset :
-                    {
-                        std::size_t{0}, std::size_t{9}
-                    })
-            {
-                const std::string doc = "[\"" + std::string(offset, 'a') + escape + "\"]";
-                CAPTURE(doc)
-                CHECK(outcome(doc, false) == outcome(doc, true));
-            }
-
-            // the escape is the last thing before end of input: no closing
-            // quote at all
-            const std::string truncated_doc = "[\"" + escape;
-            CAPTURE(truncated_doc)
-            CHECK(outcome(truncated_doc, false) == outcome(truncated_doc, true));
-        }
-    }
-
-    SECTION("truncated \\u escape at every distance from the end of input")
-    {
-        // ia.bulk_remaining() must correctly report fewer than 4 bytes for
-        // every possible count of trailing hex-looking bytes (0, 1, 2, or 3)
-        // before end of input, so the fast path declines and the byte path
-        // alone reports the "must be followed by 4 hex digits" error, at the
-        // same position, in every case
-        for (const std::string& tail :
-                {
-                    std::string{}, std::string("1"), std::string("12"), std::string("123")
-                })
-        {
-            const std::string doc = "[\"\\u" + tail;
-            CAPTURE(doc)
-            CHECK(outcome(doc, false) == outcome(doc, true));
-            CHECK(outcome(doc, false).find("must be followed by 4 hex digits") != std::string::npos);
-        }
-    }
-
-    SECTION("invalid hex digit at every position of the 4")
-    {
-        // the fast path must decline for *any* invalid byte among the 4, not
-        // just the first, and the byte path must then stop at exactly that
-        // position - same as it always has
-        for (std::size_t bad_pos = 0; bad_pos < 4; ++bad_pos)
-        {
-            std::string digits = "1234";
-            digits[bad_pos] = 'g'; // not a hex digit
-            const std::string doc = "[\"\\u" + digits + "\"]";
-            CAPTURE(doc)
-            CHECK(outcome(doc, false) == outcome(doc, true));
-            CHECK(outcome(doc, false).find("must be followed by 4 hex digits") != std::string::npos);
-        }
-    }
-
-    SECTION("random escapes")
-    {
-        // A seeded PRNG builds the 4 bytes following `\u` from a mix of hex
-        // digits and non-hex bytes, at varying distances from the start of
-        // the string, to compare the two scanners on many more shapes than
-        // are practical to enumerate by hand.
-        std::mt19937 gen(7654321); // NOLINT(cert-msc32-c,cert-msc51-cpp,bugprone-random-generator-seed)
-        const std::string hex_alphabet = "0123456789AaBbCcDdEeFf";
-        std::uniform_int_distribution<std::size_t> pick_hex(0, hex_alphabet.size() - 1);
-        std::uniform_int_distribution<int> pick_byte(1, 255); // never NUL
-        std::uniform_int_distribution<int> pick_is_hex(0, 4); // 4-in-5 chance of a hex digit
-        std::uniform_int_distribution<std::size_t> pick_offset(0, 12);
-
-        std::vector<std::string> mismatches;
-        for (int iter = 0; iter < 3000; ++iter)
-        {
-            std::string digits;
-            for (int i = 0; i < 4; ++i)
-            {
-                if (pick_is_hex(gen) != 0)
-                {
-                    digits += hex_alphabet[pick_hex(gen)];
-                }
-                else
-                {
-                    char c = static_cast<char>(pick_byte(gen));
-                    if (c == '"' || c == '\\')
-                    {
-                        // keep the string well-formed apart from the escape
-                        // itself, so any mismatch is attributable to the \u
-                        // handling and not to an unrelated quote/escape
-                        c = 'z';
-                    }
-                    digits += c;
-                }
-            }
-            const std::string doc = "[\"" + std::string(pick_offset(gen), 'a') + "\\u" + digits + "\"]";
-            if (outcome(doc, false) != outcome(doc, true))
-            {
-                mismatches.push_back(doc);
-            }
-        }
-        CAPTURE(mismatches)
-        CHECK(mismatches.empty());
-    }
+#if defined(FLT_EVAL_METHOD) && FLT_EVAL_METHOD != 0
+    // without true double precision, the fast path declines everything
+    CHECK_FALSE(fast("1.5", out));
+#else
+    CHECK(fast("1.5", out));
+    CHECK(out == 1.5);
+    CHECK(fast("+2.5e1", out));
+    CHECK(out == 25.0);
+    CHECK(fast("-25E-1", out));
+    CHECK(out == -2.5);
+    CHECK(fast("1e", out));
+    CHECK(out == 1.0);
 #endif
-}

-namespace
-{
-// the index of the decimal point (or npos) and of the end of the mantissa of a
-// number token, which the lexer records while scanning it
-std::pair<std::size_t, std::size_t> float_token_layout(const std::string& s)
-{
-    std::size_t dot = std::string::npos;
-    std::size_t mantissa_end = s.size();
-    for (std::size_t i = 0; i < s.size(); ++i)
-    {
-        if (s[i] == '.')
-        {
-            dot = i;
-        }
-        else if (s[i] == 'e' || s[i] == 'E')
-        {
-            mantissa_end = i;
-            break;
-        }
-    }
-    return {dot, mantissa_end};
-}
+    // not a number
+    CHECK_FALSE(fast("", out));
+    CHECK_FALSE(fast("-", out));
+    CHECK_FALSE(fast(".", out));
+    CHECK_FALSE(fast("1.2.3", out));
+    CHECK_FALSE(fast("1x", out));
+    CHECK_FALSE(fast("1e+", out));
+    CHECK_FALSE(fast("1e1x", out));

-template<typename FloatType>
-FloatType parse_native(const std::string& s)
-{
-    const auto layout = float_token_layout(s);
-    return nlohmann::detail::parse_float_native<FloatType>(s.data(), s.data() + s.size(), layout.first, layout.second);
-}
-
-std::uint64_t bits_of(double d)
-{
-    std::uint64_t b = 0;
-    std::memcpy(&b, &d, sizeof(b));
-    return b;
-}
-
-std::uint32_t bits_of(float f)
-{
-    std::uint32_t b = 0;
-    std::memcpy(&b, &f, sizeof(b));
-    return b;
-}
-
-std::uint64_t native_bits64(const std::string& s)
-{
-    return bits_of(parse_native<double>(s));
-}
-
-std::uint32_t native_bits32(const std::string& s)
-{
-    return bits_of(parse_native<float>(s));
-}
-} // namespace
-
-TEST_CASE("parse_float_native rounds correctly")
-{
-    SECTION("double")
-    {
-        CHECK(native_bits64("1.5") == 0x3FF8000000000000u);
-        CHECK(native_bits64("0.1") == 0x3FB999999999999Au);
-        CHECK(native_bits64("-0.0") == 0x8000000000000000u);
-        CHECK(native_bits64("0e999999999999999999999") == 0u);
-        // 2^53 + 1 is exactly between two doubles: ties to even, unless more digits follow
-        CHECK(native_bits64("9007199254740993") == 0x4340000000000000u);
-        CHECK(native_bits64("9007199254740993.0000000000000000001") == 0x4340000000000001u);
-        CHECK(native_bits64("9007199254740992.9999999999999999999") == 0x4340000000000000u);
-        // 1 + 2^-53 exactly (a tie), and one unit in the 55th digit around it
-        CHECK(native_bits64("1.00000000000000011102230246251565404236316680908203125") == 0x3FF0000000000000u);
-        CHECK(native_bits64("1.00000000000000011102230246251565404236316680908203126") == 0x3FF0000000000001u);
-        CHECK(native_bits64("1.00000000000000011102230246251565404236316680908203124") == 0x3FF0000000000000u);
-        // subnormal and overflow boundaries
-        CHECK(native_bits64("2.4703282292062327e-324") == 0u);
-        CHECK(native_bits64("2.4703282292062328e-324") == 1u);
-        CHECK(native_bits64("2.2250738585072011e-308") == 0x000FFFFFFFFFFFFFu);
-        CHECK(native_bits64("2.2250738585072012e-308") == 0x0010000000000000u);
-        CHECK(native_bits64("1.7976931348623157e308") == 0x7FEFFFFFFFFFFFFFu);
-        CHECK(native_bits64("1.7976931348623159e308") == 0x7FF0000000000000u);
-        CHECK(native_bits64("-1e400") == 0xFFF0000000000000u);
-        CHECK(native_bits64("-1e-400") == 0x8000000000000000u);
-        // exponents and zeros far beyond the range cancel out
-        CHECK(native_bits64("0." + std::string(1000, '0') + "1e1001") == 0x3FF0000000000000u);
-        CHECK(native_bits64("1" + std::string(1000, '0') + "e-1000") == 0x3FF0000000000000u);
-        CHECK(native_bits64("1e-99999999999999999999999") == 0u);
-        CHECK(native_bits64("1E+99999999999999999999999") == 0x7FF0000000000000u);
-        // more digits than any midpoint has (769): only whether a nonzero digit follows matters
-        const std::string tie = "1.00000000000000011102230246251565404236316680908203125";
-        CHECK(native_bits64(tie + std::string(800, '0')) == 0x3FF0000000000000u);
-        CHECK(native_bits64(tie + std::string(800, '0') + "1") == 0x3FF0000000000001u);
-    }
-
-    SECTION("float")
-    {
-        CHECK(native_bits32("1.5") == 0x3FC00000u);
-        CHECK(native_bits32("0.1") == 0x3DCCCCCDu);
-        CHECK(native_bits32("-0.0") == 0x80000000u);
-        // 2^24 + 1 is exactly between two floats
-        CHECK(native_bits32("16777217") == 0x4B800000u);
-        CHECK(native_bits32("16777217.000000000000000000001") == 0x4B800001u);
-        CHECK(native_bits32("16777218.999999999999999999999") == 0x4B800001u);
-        CHECK(native_bits32("16777219") == 0x4B800002u);
-        // subnormal and overflow boundaries
-        CHECK(native_bits32("3.4028235677973366e38") == 0x7F7FFFFFu);
-        CHECK(native_bits32("3.4028235677973367e38") == 0x7F800000u);
-        CHECK(native_bits32("7.006492321624085e-46") == 0u);
-        CHECK(native_bits32("7.006492321624086e-46") == 1u);
-        CHECK(native_bits32("1.1754942e-38") == 0x007FFFFFu);
-        CHECK(native_bits32("-1.17549435e-38") == 0x80800000u);
-        CHECK(native_bits32("1e39") == 0x7F800000u);
-        CHECK(native_bits32("-1e-50") == 0x80000000u);
-        // not rounded through double: its double would round to another float
-        CHECK(native_bits32("1.00000005960464477539062500000000001") == 0x3F800001u);
-        CHECK(native_bits32("9007199254740993") == 0x5A000000u);
-    }
-
-    SECTION("the conversion shared with other parsers")
-    {
-        // convert_float() gives the lexer's results, for every type
-        const std::vector<std::string> tokens =
-        {
-            "0", "-0.0", "1.5", "0.1", "1e-400", "-2.5E+3", "123456789012345678901234567890",
-            "9007199254740993.0000000000000000001", "4.9406564584124654e-324"
-        };
-        using float_json = nlohmann::basic_json<std::map, std::vector, std::string, bool, std::int64_t, std::uint64_t, float>;
-        using long_double_json = nlohmann::basic_json<std::map, std::vector, std::string, bool, std::int64_t, std::uint64_t, long double>;
-        for (const auto& t : tokens)
-        {
-            CAPTURE(t)
-            const auto layout = float_token_layout(t);
-            const char* const first = t.data();
-            const char* const last = first + t.size();
-            const auto d = nlohmann::detail::convert_float<double>(first, last, layout.first, layout.second);
-            const auto f = nlohmann::detail::convert_float<float>(first, last, layout.first, layout.second);
-            const auto ld = nlohmann::detail::convert_float<long double>(first, last, layout.first, layout.second);
-            CHECK(bits_of(d) == bits_of(json::parse(t).get<double>()));
-            CHECK(bits_of(f) == bits_of(float_json::parse(t).get<float>()));
-            CHECK(ld == long_double_json::parse(t).get<long double>());
-        }
-    }
+    // numbers that are not represented exactly on the fast path
+    CHECK_FALSE(fast("12345678901234567890", out));
+    CHECK_FALSE(fast("1e10000", out));
+    CHECK_FALSE(fast("9007199254740993", out));
+    CHECK_FALSE(fast("1e23", out));
+    CHECK_FALSE(fast("1e-23", out));
 }

 namespace
@@ -1086,6 +807,40 @@ std::size_t big_bit_length(const big_uint& a)
    }
    return n;
 }
+
+std::uint64_t bits_of(double d)
+{
+    std::uint64_t b = 0;
+    std::memcpy(&b, &d, sizeof(b));
+    return b;
+}
+
+bool eisel_lemire(const std::string& s, double& out)
+{
+    return nlohmann::detail::parse_float_eisel_lemire(s.data(), s.data() + s.size(), out);
+}
+
+// significant digits of a token, without trailing zeros
+std::size_t significant_digits(const std::string& s)
+{
+    std::string digits;
+    for (const char c : s)
+    {
+        if (c == 'e' || c == 'E')
+        {
+            break;
+        }
+        if (c >= '0' && c <= '9' && !(digits.empty() && c == '0'))
+        {
+            digits += c;
+        }
+    }
+    while (!digits.empty() && digits.back() == '0')
+    {
+        digits.pop_back();
+    }
+    return digits.size();
+}
 } // namespace

 TEST_CASE("Eisel-Lemire float conversion")
@@ -1517,33 +1272,26 @@ TEST_CASE("Eisel-Lemire float conversion")
        for (const auto& c : known)
        {
            CAPTURE(c.first)
-            CHECK(native_bits64(c.first) == c.second);
+            double out = 0;
+            if (eisel_lemire(c.first, out))
+            {
+                CHECK(bits_of(out) == c.second);
+            }
+            else
+            {
+                // only tokens with more than 19 significant digits are left to
+                // strtod: those whose value lies too close to a tie
+                CHECK(significant_digits(c.first) > 19);
+            }
        }
    }

-    SECTION("binary32")
-    {
-        using binary32 = nlohmann::detail::ieee_binary_format<24>;
-        CHECK(nlohmann::detail::eisel_lemire<binary32>(0, 1) == 0x3F800000u);
-        CHECK(nlohmann::detail::eisel_lemire<binary32>(-1, 1) == 0x3DCCCCCDu);
-        CHECK(nlohmann::detail::eisel_lemire<binary32>(-1, 15) == 0x3FC00000u);
-        CHECK(nlohmann::detail::eisel_lemire<binary32>(0, 16777217) == 0x4B800000u); // tie, to even
-        CHECK(nlohmann::detail::eisel_lemire<binary32>(0, 16777219) == 0x4B800002u); // tie, to even
-        CHECK(nlohmann::detail::eisel_lemire<binary32>(-45, 1) == 0x00000001u);
-        CHECK(nlohmann::detail::eisel_lemire<binary32>(-46, 7) == 0x00000000u);
-        CHECK(nlohmann::detail::eisel_lemire<binary32>(-46, 8) == 0x00000001u);
-        CHECK(nlohmann::detail::eisel_lemire<binary32>(-65, 9999999999999999999u) == 0x00000000u);
-        CHECK(nlohmann::detail::eisel_lemire<binary32>(20, 3402823466385288598u) == 0x7F7FFFFFu);
-        CHECK(nlohmann::detail::eisel_lemire<binary32>(20, 3402823669209384635u) == 0x7F800000u);
-        CHECK(nlohmann::detail::eisel_lemire<binary32>(39, 1) == 0x7F800000u);
-        CHECK(nlohmann::detail::eisel_lemire<binary32>(-5, 0) == 0x00000000u);
-    }
-
    SECTION("round trip")
    {
-        // every double written by to_chars and read back, and its 17-digit
-        // form with trailing digits that make the token longer than 19 digits
+        // every double written by to_chars and read back, also with trailing
+        // digits that make the token longer than 19 digits
        std::uint64_t state = 5295;
+        std::size_t declined = 0;
        for (int i = 0; i < 200000; ++i)
        {
            state ^= state << 13u;
@@ -1565,51 +1313,30 @@ TEST_CASE("Eisel-Lemire float conversion")
            const char* end = nlohmann::detail::to_chars(buffer.data(), buffer.data() + buffer.size(), d);
            const std::string token(buffer.data(), static_cast<std::size_t>(end - buffer.data()));
            CAPTURE(token)
-            CHECK(native_bits64(token) == b);
+            double out = 0;
+            REQUIRE(eisel_lemire(token, out));
+            CHECK(bits_of(out) == b);

-            // insert digits before the exponent of the 17-digit form: that
-            // form lies strictly inside the rounding interval of the double
-            // (the shortest one may lie on its boundary), and the digits move
-            // it by far less than the distance to the boundary, so the value
-            // must not change
-            std::array<char, 64> digits17{};
-            static_cast<void>(std::snprintf(digits17.data(), digits17.size(), "%.17g", d)); // NOLINT(cppcoreguidelines-pro-type-vararg,hicpp-vararg)
-            std::string longer = digits17.data();
+            // insert digits before the exponent: the value moves by far less
+            // than the distance to the rounding boundary, so it must not change
+            std::string longer = token;
            const std::size_t e = longer.find('e');
            const std::size_t dot = longer.find('.');
            const std::string extra = dot == std::string::npos ? ".000000000000000000001" : "000000000000000000001";
            longer.insert(e == std::string::npos ? longer.size() : e, extra);
            CAPTURE(longer)
-            CHECK(native_bits64(longer) == b);
-        }
-    }
-
-    SECTION("round trip, binary32")
-    {
-        std::uint32_t state = 5295;
-        for (int i = 0; i < 100000; ++i)
-        {
-            state ^= state << 13u;
-            state ^= state >> 17u;
-            state ^= state << 5u;
-            std::uint32_t b = state;
-            if ((b & 0x7F800000u) == 0x7F800000u)
+            if (eisel_lemire(longer, out))
            {
-                continue; // infinity or NaN
+                CHECK(bits_of(out) == b);
            }
-            if (i % 4 == 0)
+            else
            {
-                b &= 0x807FFFFFu; // subnormals
+                // w and w + 1 round differently: only when the value is very
+                // close to a rounding boundary
+                ++declined;
            }
-            float f = 0;
-            std::memcpy(&f, &b, sizeof(f));
-
-            std::array<char, 64> buffer{};
-            const char* end = nlohmann::detail::to_chars(buffer.data(), buffer.data() + buffer.size(), f);
-            const std::string token(buffer.data(), static_cast<std::size_t>(end - buffer.data()));
-            CAPTURE(token)
-            CHECK(native_bits32(token) == b);
        }
+        CHECK(declined < 1000); // 107 of the 200,000
    }

    SECTION("used by the lexer")
@@ -1623,184 +1350,3 @@ TEST_CASE("Eisel-Lemire float conversion")
                             "[json.exception.out_of_range.406] number overflow parsing '1.7976931348623159e308'", json::out_of_range&);
    }
 }
-
-namespace
-{
-using float_json = nlohmann::basic_json<std::map, std::vector, std::string, bool, std::int64_t, std::uint64_t, float>;
-
-// the bits of the float that parse() gives for a token, via both scanners;
-// the value must be the same for both
-template<typename Json, typename Bits>
-void check_parse(const std::string& token, Bits expected, Bits infinity)
-{
-    std::stringstream stream(token);
-    if ((expected & ~(Bits{1} << ((8 * sizeof(Bits)) - 1))) == infinity)
-    {
-        Json _;
-        CHECK_THROWS_WITH_AS(_ = Json::parse(token), ("[json.exception.out_of_range.406] number overflow parsing '" + token + "'").c_str(), typename Json::out_of_range&);
-        CHECK_THROWS_WITH_AS(_ = Json::parse(stream), ("[json.exception.out_of_range.406] number overflow parsing '" + token + "'").c_str(), typename Json::out_of_range&);
-        return;
-    }
-    const Json contiguous = Json::parse(token);
-    const Json streamed = Json::parse(stream);
-    if (contiguous.is_number_float()) // not an integer that fits
-    {
-        CHECK(bits_of(contiguous.template get<typename Json::number_float_t>()) == expected);
-        CHECK(bits_of(streamed.template get<typename Json::number_float_t>()) == expected);
-    }
-    else
-    {
-        CHECK(streamed.is_number_integer());
-    }
-}
-} // namespace
-
-TEST_CASE("float conversion of hard cases")
-{
-    // see float_hard_cases.hpp
-    for (const auto& c : float_hard_cases::cases())
-    {
-        const std::string token = c.token;
-        CAPTURE(token)
-        CHECK(native_bits64(token) == c.bits64);
-        CHECK(native_bits32(token) == c.bits32);
-        check_parse<json>(token, c.bits64, std::uint64_t{0x7FF0000000000000u});
-        check_parse<float_json>(token, c.bits32, std::uint32_t{0x7F800000u});
-    }
-}
-
-TEST_CASE("float overflow and underflow in the parser")
-{
-    SECTION("double")
-    {
-        check_parse<json>("1.7976931348623157e308", std::uint64_t{0x7FEFFFFFFFFFFFFFu}, std::uint64_t{0x7FF0000000000000u});
-        check_parse<json>("1.7976931348623159e308", std::uint64_t{0x7FF0000000000000u}, std::uint64_t{0x7FF0000000000000u});
-        check_parse<json>("-1e309", std::uint64_t{0xFFF0000000000000u}, std::uint64_t{0x7FF0000000000000u});
-        check_parse<json>("1" + std::string(400, '0'), std::uint64_t{0x7FF0000000000000u}, std::uint64_t{0x7FF0000000000000u});
-        check_parse<json>("1e99999999999999999999", std::uint64_t{0x7FF0000000000000u}, std::uint64_t{0x7FF0000000000000u});
-        // an underflow gives a zero with the sign of the token
-        check_parse<json>("1e-400", std::uint64_t{0}, std::uint64_t{0x7FF0000000000000u});
-        check_parse<json>("-1e-400", std::uint64_t{0x8000000000000000u}, std::uint64_t{0x7FF0000000000000u});
-        check_parse<json>("-2.4703282292062327e-324", std::uint64_t{0x8000000000000000u}, std::uint64_t{0x7FF0000000000000u});
-        check_parse<json>("0." + std::string(400, '0') + "1", std::uint64_t{0}, std::uint64_t{0x7FF0000000000000u});
-    }
-
-    SECTION("float")
-    {
-        check_parse<float_json>("3.4028234e38", std::uint32_t{0x7F7FFFFFu}, std::uint32_t{0x7F800000u});
-        check_parse<float_json>("3.4028236e38", std::uint32_t{0x7F800000u}, std::uint32_t{0x7F800000u});
-        check_parse<float_json>("-1e39", std::uint32_t{0xFF800000u}, std::uint32_t{0x7F800000u});
-        check_parse<float_json>("1e-46", std::uint32_t{0}, std::uint32_t{0x7F800000u});
-        check_parse<float_json>("-1e-46", std::uint32_t{0x80000000u}, std::uint32_t{0x7F800000u});
-        check_parse<float_json>("-7.006492321624085e-46", std::uint32_t{0x80000000u}, std::uint32_t{0x7F800000u});
-        check_parse<float_json>("-7.006492321624086e-46", std::uint32_t{0x80000001u}, std::uint32_t{0x7F800000u});
-    }
-}
-
-TEST_CASE("string scanning kernels")
-{
-    // the word-at-a-time kernels must stop exactly where a byte-by-byte scan
-    // stops, for any content, length, and alignment
-    const auto reference_special = [](const unsigned char* data, std::size_t n)
-    {
-        std::size_t i = 0;
-        while (i < n && !nlohmann::detail::is_string_special(data[i]))
-        {
-            ++i;
-        }
-        return i;
-    };
-    const auto reference_copyable = [](const unsigned char* data, std::size_t n)
-    {
-        std::size_t i = 0;
-        while (i < n && nlohmann::detail::is_ascii_copyable(data[i]))
-        {
-            ++i;
-        }
-        return i;
-    };
-    const auto reference_bulk_run = [](const unsigned char* data, std::size_t n)
-    {
-        std::size_t i = 0;
-        while (i < n)
-        {
-            if (data[i] < 0x80u)
-            {
-                if (nlohmann::detail::is_string_special(data[i]))
-                {
-                    break;
-                }
-                ++i;
-                continue;
-            }
-            const std::size_t seq = nlohmann::detail::validate_one_utf8(data + i, n - i);
-            if (seq == 0)
-            {
-                break;
-            }
-            i += seq;
-        }
-        return i;
-    };
-
-    // pieces: ordinary ASCII, stops, DEL, well-formed sequences of every
-    // length, and ill-formed or truncated ones
-    const std::vector<std::string> pieces =
-    {
-        "a", "Z", " ", "~", "0123456789", "\"", "\\", std::string(1, '\0'), "\n", "\x1F", "\x7F",
-        "\xC3\xA4", "\xE2\x82\xAC", "\xE6\x97\xA5\xE6\x9C\xAC", "\xF0\x9F\x98\x80", "\xED\x9F\xBF",
-        "\x80", "\xC0\x80", "\xC3", "\xE2\x82", "\xED\xA0\x80", "\xF4\x90\x80\x80", "\xFF",
-    };
-    std::uint64_t state = 5295;
-    const auto next = [&state]()
-    {
-        state ^= state << 13u;
-        state ^= state >> 7u;
-        state ^= state << 17u;
-        return state;
-    };
-    // the upper half as a 32-bit value: converts to std::size_t implicitly on
-    // every platform (a cast of std::uint64_t is useless where both are the
-    // same type, and required where std::size_t is 32 bits wide)
-    const auto next_small = [&next]()
-    {
-        return static_cast<std::uint32_t>(next() >> 32u);
-    };
-    for (int round = 0; round < 100000; ++round)
-    {
-        // mostly ordinary text, so that runs span several words
-        std::string text(next_small() % 8u, '.');
-        const std::size_t count = next_small() % 12u;
-        for (std::size_t k = 0; k < count; ++k)
-        {
-            const std::size_t p = (next() % 4 == 0) ? next_small() % pieces.size() : 0;
-            text += pieces[p];
-            text += std::string(next_small() % 10u, 'x');
-        }
-        const auto* data = reinterpret_cast<const unsigned char*>(text.data()); // NOLINT(cppcoreguidelines-pro-type-reinterpret-cast)
-        for (std::size_t offset = 0; offset < 3 && offset <= text.size(); ++offset)
-        {
-            const std::size_t n = text.size() - offset;
-            CAPTURE(text)
-            CAPTURE(offset)
-            CHECK(nlohmann::detail::find_string_special(data + offset, n) == reference_special(data + offset, n));
-            CHECK(nlohmann::detail::find_ascii_copyable_run(data + offset, n) == reference_copyable(data + offset, n));
-            CHECK(nlohmann::detail::scalar_string_bulk_run(data + offset, n) == reference_bulk_run(data + offset, n));
-        }
-    }
-
-    // the trailing-zero count, whichever implementation the compiler gets
-    for (int k = 0; k < 64; ++k)
-    {
-        const std::uint64_t bit = std::uint64_t{1} << k;
-        CHECK(nlohmann::detail::count_trailing_zeros(bit) == k);
-        CHECK(nlohmann::detail::count_trailing_zeros(bit | (bit << 1u) | 0x8000000000000000u) == k);
-    }
-
-    // eight bytes as a little-endian word, at any alignment
-    const std::array<unsigned char, 16> bytes = {{0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F, 0xFF}};
-    CHECK(nlohmann::detail::read_eight_bytes(bytes.data()) == 0x0807060504030201u);
-    CHECK(nlohmann::detail::read_eight_bytes(bytes.data() + 1) == 0x0908070605040302u);
-    CHECK(nlohmann::detail::read_eight_bytes(bytes.data() + 8) == 0xFF0F0E0D0C0B0A09u);
-    CHECK(nlohmann::detail::read_eight_bytes(reinterpret_cast<const char*>(bytes.data()) + 3) == 0x0B0A090807060504u);
-}
@@ -0,0 +1,236 @@
+//     __ _____ _____ _____
+//  __|  |   __|     |   | |  JSON for Modern C++ (supporting code)
+// |  |  |__   |  |  | | | |  version 3.12.0
+// |_____|_____|_____|_|___|  https://github.com/nlohmann/json
+//
+// SPDX-FileCopyrightText: 2013-2026 Niels Lohmann <https://nlohmann.me>
+// SPDX-License-Identifier: MIT
+
+#include "doctest_compatibility.h"
+
+#include <nlohmann/json.hpp>
+using nlohmann::json;
+
+#include <array>
+#include <cstdint>
+#include <cstdio>
+#include <fstream>
+#include <memory>
+#include <random>
+#include <string>
+#include <thread>
+#include <vector>
+
+// Parsing from a FILE* locks the file once and reads it with the unlocked
+// stdio functions (see JSON_DISABLE_UNLOCKED_FILE_IO). These tests pin that
+// this is not observable: the results are the same, the file is unlocked
+// again when parsing ends - also with an exception - and the same thread can
+// keep using the file while it is locked, e.g., from a SAX callback.
+
+namespace
+{
+// a file name of its own for every run: the test runs for several C++
+// standards and configurations at the same time, in the same directory
+std::string temp_file_name()
+{
+    std::random_device rd;
+    return "unit-file_input-" + std::to_string(rd()) + ".tmp";
+}
+
+using file_ptr = std::unique_ptr<std::FILE, int (*)(std::FILE*)>;
+
+// write @a content to the file @a name and open it for reading
+file_ptr open_with(const char* name, const std::string& content)
+{
+    {
+        std::ofstream file(name, std::ios::binary);
+        file << content;
+    }
+    return {std::fopen(name, "rb"), &std::fclose};
+}
+
+// The stdio lock is recursive, so whether parsing released it can only be
+// seen from another thread: ftrylockfile() fails there while this thread
+// holds the lock. ftrylockfile() is POSIX; elsewhere, the check is skipped.
+#if defined(__GLIBC__) || defined(__APPLE__) || defined(__FreeBSD__) || defined(__NetBSD__) || defined(__OpenBSD__)
+void check_unlocked(std::FILE* f)
+{
+    int result = -1;
+    std::thread other([f, &result]
+    {
+        result = ftrylockfile(f);
+        if (result == 0)
+        {
+            funlockfile(f);
+        }
+    });
+    other.join();
+    CHECK(result == 0);
+}
+#else
+void check_unlocked(std::FILE* /*f*/) {}
+#endif
+
+// SAX consumer that also reads the position of the file it is parsing, which
+// takes the file's lock again on the same thread
+class position_reading_sax : public nlohmann::json_sax<json>
+{
+  public:
+    explicit position_reading_sax(std::FILE* f) : m_file(f) {}
+    position_reading_sax(const position_reading_sax&) = delete;
+    position_reading_sax(position_reading_sax&&) = delete;
+    position_reading_sax& operator=(const position_reading_sax&) = delete;
+    position_reading_sax& operator=(position_reading_sax&&) = delete;
+    ~position_reading_sax() override = default;
+
+    bool null() override
+    {
+        return record();
+    }
+    bool boolean(bool /*val*/) override
+    {
+        return record();
+    }
+    bool number_integer(number_integer_t /*val*/) override
+    {
+        return record();
+    }
+    bool number_unsigned(number_unsigned_t /*val*/) override
+    {
+        return record();
+    }
+    bool number_float(number_float_t /*val*/, const string_t& /*s*/) override
+    {
+        return record();
+    }
+    bool string(string_t& /*val*/) override
+    {
+        return record();
+    }
+    bool binary(binary_t& /*val*/) override
+    {
+        return record();
+    }
+    bool start_object(std::size_t /*elements*/) override
+    {
+        return record();
+    }
+    bool key(string_t& /*val*/) override
+    {
+        return record();
+    }
+    bool end_object() override
+    {
+        return record();
+    }
+    bool start_array(std::size_t /*elements*/) override
+    {
+        return record();
+    }
+    bool end_array() override
+    {
+        return record();
+    }
+    bool parse_error(std::size_t /*position*/, const std::string& /*last_token*/, const nlohmann::detail::exception& /*ex*/) override
+    {
+        return false;
+    }
+
+    const std::vector<long>& positions() const
+    {
+        return m_positions;
+    }
+
+  private:
+    bool record()
+    {
+        m_positions.push_back(std::ftell(m_file));
+        return true;
+    }
+
+    std::FILE* m_file;
+    std::vector<long> m_positions{}; // NOLINT(readability-redundant-member-init)
+};
+}  // namespace
+
+TEST_CASE("parsing from a FILE*")
+{
+    const std::string temp_name = temp_file_name();
+    const char* const name = temp_name.c_str();
+    const std::string input = "{\"a\": [1, -2.5, \"three\", true, null], \"b\": {\"c\": \"caf\xc3\xa9\"}}";
+
+    SECTION("values are the same as when parsing from a string")
+    {
+        const file_ptr f = open_with(name, input);
+        REQUIRE(f != nullptr);
+        CHECK(json::parse(f.get()) == json::parse(input));
+        // the whole input was consumed
+        std::array<char, 8> rest{};
+        CHECK(std::fgets(rest.data(), static_cast<int>(rest.size()), f.get()) == nullptr);
+        check_unlocked(f.get());
+    }
+
+    SECTION("the file is unlocked after a parse error")
+    {
+        const file_ptr f = open_with(name, "[1, 2, x]");
+        REQUIRE(f != nullptr);
+        json _;
+        CHECK_THROWS_WITH_AS(_ = json::parse(f.get()),
+                             "[json.exception.parse_error.101] parse error at line 1, column 8: syntax error while parsing value - invalid literal; last read: '2, x'",
+                             json::parse_error&);
+        check_unlocked(f.get());
+
+        // the file is still usable: the rest of the input is there
+        std::array<char, 8> rest{};
+        CHECK(std::fgets(rest.data(), static_cast<int>(rest.size()), f.get()) != nullptr);
+        CHECK(std::string(rest.data()) == "]");
+    }
+
+    SECTION("the file can be parsed again and read with stdio afterwards")
+    {
+        const file_ptr f = open_with(name, "[1] [2] tail");
+        REQUIRE(f != nullptr);
+
+        // sax_parse with strict == false stops after the first value; an array
+        // ends with its closing bracket, so the space after it is not read
+        json j;
+        nlohmann::detail::json_sax_dom_parser<json, nlohmann::detail::string_input_adapter_type> sax1(j);
+        CHECK(json::sax_parse(f.get(), &sax1, json::input_format_t::json, false));
+        CHECK(j == json({1}));
+        check_unlocked(f.get());
+
+        json k;
+        nlohmann::detail::json_sax_dom_parser<json, nlohmann::detail::string_input_adapter_type> sax2(k);
+        CHECK(json::sax_parse(f.get(), &sax2, json::input_format_t::json, false));
+        CHECK(k == json({2}));
+        check_unlocked(f.get());
+
+        std::array<char, 8> rest{};
+        CHECK(std::fgets(rest.data(), static_cast<int>(rest.size()), f.get()) != nullptr);
+        CHECK(std::string(rest.data()) == " tail");
+    }
+
+    SECTION("the same thread can use the file while it is parsed")
+    {
+        const file_ptr f = open_with(name, "[10, 20, 30]");
+        REQUIRE(f != nullptr);
+        position_reading_sax sax(f.get());
+        CHECK(json::sax_parse(f.get(), &sax));
+        // start_array, three numbers, end_array
+        CHECK(sax.positions().size() == 5);
+        CHECK(sax.positions().front() == 1);
+        check_unlocked(f.get());
+    }
+
+    SECTION("binary formats read from a FILE*")
+    {
+        const json j = {{"string", std::string(300, 'x')}, {"array", {1, 2, 3}}, {"number", 1.5}};
+        const std::vector<std::uint8_t> cbor = json::to_cbor(j);
+        const file_ptr f = open_with(name, std::string(cbor.begin(), cbor.end()));
+        REQUIRE(f != nullptr);
+        CHECK(json::from_cbor(f.get()) == j);
+        check_unlocked(f.get());
+    }
+
+    static_cast<void>(std::remove(name));
+}
@@ -260,11 +260,10 @@ struct LocaleSwitchingSax final: public nlohmann::json_sax<json>

 TEST_CASE("locale changes between lexer construction and number conversion (#5198)")
 {
-    // float and double are converted without the locale. A long double that
-    // is not binary64 can take the strtold fallback, which honors the locale
-    // that is current at conversion time. The numbers are chosen so that it
-    // does: too many significant digits for Clinger's fast path, an underflow
-    // that std::from_chars rejects, and a plain value.
+    // The numbers are chosen so that the conversion also takes the strtod
+    // fallback, which honors the locale that is current at conversion time:
+    // too many significant digits for Clinger's fast path, an underflow that
+    // std::from_chars rejects, and a plain value.
    const std::vector<std::string> numbers = {"3.14159265358979323846", "1.5e-400", "12.34", "-0.000123456789012345678"};
    std::string text = "[";
    for (const auto& n : numbers)
@@ -328,8 +327,7 @@ TEST_CASE("locale changes between lexer construction and number conversion (#519
            }
        }

-        // a long double goes through std::strtold unless it is binary64 or
-        // std::from_chars supports it
+        // a long double goes through std::strtold unless std::from_chars supports it
        {
            bool switched = false;
            const auto cb = [&](int /*depth*/, long_double_json::parse_event_t event, long_double_json& /*parsed*/) noexcept
@@ -355,15 +353,8 @@ TEST_CASE("locale with a multi-byte decimal point")
 {
    // Some locales use a decimal point that is not a single character, e.g.
    // U+066B ARABIC DECIMAL SEPARATOR (two bytes in UTF-8). It cannot be
-    // substituted in place for '.', so the strtold fallback (only for long
-    // double formats other than binary64) converts a copy of the token with
-    // the whole decimal point instead (#5660). The values must be those of the
-    // "C" locale.
-    using long_double_json = nlohmann::basic_json<std::map, std::vector, std::string, bool, std::int64_t, std::uint64_t, long double>;
-    const char* const long_double_numbers = "[3.14159265358979323846, 1.5e-400, -0.000123456789012345678]";
-    REQUIRE(std::setlocale(LC_NUMERIC, "C") != nullptr);
-    const long_double_json expected_long_double = long_double_json::parse(long_double_numbers);
-
+    // substituted in place for '.', so the strtod fallback stops early. The
+    // conversion must still terminate rather than retry forever.
    const std::array<const char*, 6> names = {{"ar_EG.UTF-8", "ar_SA.UTF-8", "fa_IR.UTF-8", "ps_AF.UTF-8", "ar_EG", "fa_IR"}};
    bool tested = false;
    for (const char* name : names)
@@ -381,20 +372,12 @@ TEST_CASE("locale with a multi-byte decimal point")
        tested = true;

        // too many significant digits for Clinger's fast path, and an underflow
-        // that std::from_chars rejects: double does not depend on the locale
+        // that std::from_chars rejects: both reach the strtod fallback
        json j;
        CHECK_NOTHROW(j = json::parse("[3.14159265358979323846, 1.5e-400, -0.000123456789012345678]"));
        CHECK(j.is_array());
-        CHECK(j[0] == 3.14159265358979323846);
-        CHECK(j[1] == 0.0);
-        CHECK(j[2] == -0.000123456789012345678);
        CHECK(json::accept("3.14159265358979323846"));

-        // a long double that reaches the strtold fallback is not truncated
-        long_double_json ld;
-        CHECK_NOTHROW(ld = long_double_json::parse(long_double_numbers));
-        CHECK(ld == expected_long_double);
-
        // a value the locale-independent paths convert is not affected
        CHECK(json::parse("12.5") == 12.5);
    }
@@ -20,6 +20,7 @@
 #include <nlohmann/json.hpp>
 using nlohmann::json;

+#include <algorithm>
 #include <cstddef>
 #include <sstream>
 #include <streambuf>
@@ -72,6 +73,40 @@ class no_putback_streambuf : public std::streambuf
    std::size_t m_pos = 0;
 };

+// A streambuf that serves its input in get areas of a fixed size, so that the
+// end of a number falls on every possible offset of a get area. The lexer scans
+// the get area directly; the stream position must not depend on its size.
+class chunked_streambuf : public std::streambuf
+{
+  public:
+    chunked_streambuf(std::string s, std::size_t chunk_size)
+        : m_data(std::move(s)), m_chunk_size(chunk_size)
+    {}
+
+  protected:
+    int_type underflow() override
+    {
+        if (gptr() < egptr())
+        {
+            return traits_type::to_int_type(*gptr());
+        }
+        m_pos += static_cast<std::size_t>(egptr() - eback());
+        if (m_pos >= m_data.size())
+        {
+            setg(nullptr, nullptr, nullptr);
+            return traits_type::eof();
+        }
+        char* const begin = &m_data[m_pos];
+        setg(begin, begin, begin + (std::min)(m_chunk_size, m_data.size() - m_pos));
+        return traits_type::to_int_type(*gptr());
+    }
+
+  private:
+    std::string m_data;
+    std::size_t m_pos = 0;
+    std::size_t m_chunk_size;
+};
+
 // read the characters that are left in a stream
 std::string remaining(std::istream& is)
 {
@@ -263,4 +298,26 @@ TEST_CASE("JSON_PRECISE_STREAM_POSITION")
        json _;
        CHECK_THROWS_WITH_AS(_ = json::parse(is), "[json.exception.parse_error.101] parse error: attempting to parse an empty input; check that your input string or stream contains the expected JSON", json::parse_error&);
    }
+
+    SECTION("the position does not depend on the get area of the streambuf")
+    {
+        const std::vector<std::size_t> chunk_sizes = {1, 2, 3, 4, 5, 7, 8, 13, 4096};
+        for (const std::size_t chunk_size : chunk_sizes)
+        {
+            CAPTURE(chunk_size)
+            chunked_streambuf buf("12345678901234567890true\"a long string value\"-1.25e+3,[1,2]42", chunk_size);
+            std::istream input(&buf);
+            json j;
+
+            input >> j;
+            CHECK(j == 12345678901234567890u);
+            input >> j;
+            CHECK(j == true);
+            input >> j;
+            CHECK(j == "a long string value");
+            input >> j;
+            CHECK(j == -1250.0);
+            CHECK(remaining(input) == ",[1,2]42");
+        }
+    }
 }
@@ -0,0 +1,417 @@
+//     __ _____ _____ _____
+//  __|  |   __|     |   | |  JSON for Modern C++ (supporting code)
+// |  |  |__   |  |  | | | |  version 3.12.0
+// |_____|_____|_____|_|___|  https://github.com/nlohmann/json
+//
+// SPDX-FileCopyrightText: 2013-2026 Niels Lohmann <https://nlohmann.me>
+// SPDX-License-Identifier: MIT
+
+#include "doctest_compatibility.h"
+
+// the library undefines its configuration macros at the end of the header
+#if defined(JSON_DISABLE_STREAM_BULK_SCAN) && JSON_DISABLE_STREAM_BULK_SCAN
+    #define TEST_STREAM_BULK_SCAN 0
+#else
+    #define TEST_STREAM_BULK_SCAN 1
+#endif
+
+#include <nlohmann/json.hpp>
+using nlohmann::json;
+
+#include <algorithm>
+#include <cstddef>
+#include <cstdint>
+#include <cstdio>
+#include <fstream>
+#include <istream>
+#include <random>
+#include <sstream>
+#include <streambuf>
+#include <string>
+#include <utility>
+#include <vector>
+
+// The lexer scans the characters in the get area of a std::istream's
+// streambuf directly instead of reading them one at a time. These tests pin
+// that this is not observable: for any get area size - including a streambuf
+// without a get area, which still takes the character-at-a-time path - the
+// parsed values, the exception messages (including the "last read" token),
+// the stream state, and the characters left in the stream are the same. See
+// unit-stream-bulk-scan-disabled.cpp for JSON_DISABLE_STREAM_BULK_SCAN.
+
+namespace
+{
+// A streambuf that serves its input in get areas of a fixed size, so that
+// tokens, numbers, UTF-8 sequences, and indentation cross the end of the get
+// area at every possible offset. With a size of 0, it keeps no get area at all
+// and serves every character from underflow()/uflow().
+class chunked_streambuf : public std::streambuf
+{
+  public:
+    chunked_streambuf(std::string s, std::size_t chunk_size)
+        : m_data(std::move(s)), m_chunk_size(chunk_size)
+    {}
+
+  protected:
+    int_type underflow() override
+    {
+        if (m_chunk_size == 0)
+        {
+            return m_pos < m_data.size() ? traits_type::to_int_type(m_data[m_pos]) : traits_type::eof();
+        }
+        if (gptr() < egptr())
+        {
+            return traits_type::to_int_type(*gptr());
+        }
+        // the previous get area has been consumed
+        m_pos += static_cast<std::size_t>(egptr() - eback());
+        if (m_pos >= m_data.size())
+        {
+            setg(nullptr, nullptr, nullptr);
+            return traits_type::eof();
+        }
+        char* const begin = &m_data[m_pos];
+        setg(begin, begin, begin + (std::min)(m_chunk_size, m_data.size() - m_pos));
+        return traits_type::to_int_type(*gptr());
+    }
+
+    int_type uflow() override
+    {
+        if (m_chunk_size == 0)
+        {
+            return m_pos < m_data.size() ? traits_type::to_int_type(m_data[m_pos++]) : traits_type::eof();
+        }
+        return std::streambuf::uflow();
+    }
+
+  private:
+    std::string m_data;
+    std::size_t m_pos = 0;
+    std::size_t m_chunk_size;
+};
+
+// how a test reads from the stream
+enum class read_mode
+{
+    extract,         // up to four times operator>>, as for concatenated values
+    parse,           // json::parse(stream)
+    parse_lenient,   // json::parse(stream) with comments
+};
+
+// Read @a input from a chunked_streambuf and describe everything observable:
+// the values or the exception, the stream state after each value, and the
+// characters left in the stream.
+std::string observe(const std::string& input, std::size_t chunk_size, read_mode mode)
+{
+    chunked_streambuf buf(input, chunk_size);
+    std::istream is(&buf);
+    std::string result;
+    for (int i = 0; i < 4; ++i)
+    {
+        json j;
+        try
+        {
+            if (mode == read_mode::extract)
+            {
+                is >> j;
+            }
+            else
+            {
+                j = json::parse(is, nullptr, true, mode == read_mode::parse_lenient);
+            }
+            result += "value " + j.dump() + "; state " + std::to_string(static_cast<unsigned int>(is.rdstate())) + "\n";
+        }
+        catch (const json::exception& e)
+        {
+            result += std::string("exception ") + e.what() + "\n";
+            break;
+        }
+        if (mode != read_mode::extract)
+        {
+            break;
+        }
+        is.clear();
+    }
+
+    is.clear();
+    result += "remaining ";
+    char c = 0;
+    while (is.get(c))
+    {
+        result += c;
+    }
+    return result;
+}
+
+// get area sizes that put every boundary everywhere in short inputs, plus one
+// that holds most inputs completely
+std::vector<std::size_t> chunk_sizes()
+{
+    return {1, 2, 3, 4, 5, 7, 8, 9, 13, 16, 64, 4096};
+}
+
+// valid and invalid inputs covering every token type and every bulk path:
+// strings (plain runs, escapes, UTF-8), numbers (all grammar parts, too large
+// for an integer), and indentation
+std::vector<std::string> corpus()
+{
+    return
+    {
+        // numbers, terminated in every way
+        "0", "-0", "123", "-123", "1.5", "-1.5e+10", "2E-3", "123456789012345678901234567890",
+        "18446744073709551615", "18446744073709551616", "-9223372036854775809",
+        "123 456", "123,456", "123]", "1true", "42\nfoo", "1.25e3}", "7\t8\r9",
+        // malformed numbers
+        "1.", "-", "1e", "1e+", "01", "-a", "1.x", "1ee5",
+        // strings
+        R"("")", R"("abc")", R"("a long string with a run of ordinary characters to scan in bulk")",
+        R"("escapes \" \\ \/ \b \f \n \r \t é 😀")",
+        "\"UTF-8: \xc3\xa9 \xe2\x82\xac \xf0\x9f\x98\x80 done\"",
+        // malformed strings
+        R"("unterminated)", "\"control\x01character\"", "\"ill-formed \xc3\x28 UTF-8\"", R"("bad \x escape")",
+        R"("\ud800 lone surrogate")",
+        // literals
+        "true", "false", "null", "tru", "nul", "falsey",
+        // structures
+        "[]", "{}", "[1,2,3]", R"({"a":1,"b":[true,false,null],"c":{"d":"e"}})", "[1,]", R"({"a" 1})", "[[[[[]]]]]",
+        // pretty-printed
+        "{\n    \"key\": [\n        1,\n        -2.5,\n        \"three\"\n    ]\n}",
+        "[\n                                \"deep\"\n                                ]",
+        "{\n    \"a\": 1,\n    \"b\": 2x\n}",
+        // concatenated values and whitespace
+        "1 2 3", R"("a""b")", "[1][2]", "{}{}", " \n\t 42 \n\t ", "",
+        // comments (only accepted by parse_lenient)
+        "/* comment */ 1", "// comment\n[1, /* c */ 2]",
+        // byte order mark
+        "\xef\xbb\xbf[1]",
+    };
+}
+}  // namespace
+
+TEST_CASE("parsing from a std::istream scans the get area in bulk")
+{
+    SECTION("results do not depend on the get area")
+    {
+        const std::vector<read_mode> read_modes = {read_mode::extract, read_mode::parse, read_mode::parse_lenient};
+        for (const auto& input : corpus())
+        {
+            for (const read_mode mode : read_modes)
+            {
+                // no get area: the character-at-a-time path
+                const std::string expected = observe(input, 0, mode);
+                for (const std::size_t chunk_size : chunk_sizes())
+                {
+                    CAPTURE(input)
+                    CAPTURE(chunk_size)
+                    CAPTURE(static_cast<int>(mode))
+                    CHECK(observe(input, chunk_size, mode) == expected);
+                }
+            }
+        }
+    }
+
+    SECTION("values are the same as when parsing from a string")
+    {
+        const std::string input = R"({"name": "nlohmann::json", "numbers": [1, -2, 3.5, 4e10, 18446744073709551615],)"
+                                  "\n    \"text\": \"caf\xc3\xa9 \\u00e9 \\\"quoted\\\"\", \"nested\": [[{}], [[]]], \"flags\": [true, false, null]}";
+        const json expected = json::parse(input);
+        for (const std::size_t chunk_size : chunk_sizes())
+        {
+            CAPTURE(chunk_size)
+            chunked_streambuf buf(input, chunk_size);
+            std::istream is(&buf);
+            CHECK(json::parse(is) == expected);
+        }
+
+        std::istringstream ss(input);
+        CHECK(json::parse(ss) == expected);
+    }
+
+    SECTION("a token that spans several get areas is reported completely")
+    {
+        // the error is found after the string has crossed many get areas; the
+        // token string holds everything since the start of the last token
+        const std::string input = R"(["this string is longer than every get area", tru])";
+        for (const std::size_t chunk_size : chunk_sizes())
+        {
+            CAPTURE(chunk_size)
+            chunked_streambuf buf(input, chunk_size);
+            std::istream is(&buf);
+            json j;
+            CHECK_THROWS_WITH_AS(is >> j,
+                                 "[json.exception.parse_error.101] parse error at line 1, column 50: syntax error while parsing value - invalid literal; last read: '\"this string is longer than every get area\", tru]'",
+                                 json::parse_error&);
+        }
+
+        const std::string unterminated = R"("this string is longer than every get area)";
+        for (const std::size_t chunk_size : chunk_sizes())
+        {
+            CAPTURE(chunk_size)
+            chunked_streambuf buf(unterminated, chunk_size);
+            std::istream is(&buf);
+            json j;
+            CHECK_THROWS_WITH_AS(is >> j,
+                                 "[json.exception.parse_error.101] parse error at line 1, column 43: syntax error while parsing value - invalid string: missing closing quote; last read: '\"this string is longer than every get area'",
+                                 json::parse_error&);
+        }
+    }
+
+    SECTION("an error before the first token reports everything read")
+    {
+        chunked_streambuf buf("  \n  x", 2);
+        std::istream is(&buf);
+        json j;
+        CHECK_THROWS_WITH_AS(is >> j,
+                             "[json.exception.parse_error.101] parse error at line 2, column 3: syntax error while parsing value - invalid literal; last read: '  <U+000A>  x'",
+                             json::parse_error&);
+    }
+
+    SECTION("lines and columns are counted across get areas")
+    {
+        const std::string input = "[\n    1,\n    \"two\",\n    3.0,\n    x\n]";
+        for (const std::size_t chunk_size : chunk_sizes())
+        {
+            CAPTURE(chunk_size)
+            chunked_streambuf buf(input, chunk_size);
+            std::istream is(&buf);
+            json j;
+            CHECK_THROWS_WITH_AS(is >> j,
+                                 "[json.exception.parse_error.101] parse error at line 5, column 5: syntax error while parsing value - invalid literal; last read: '3.0,<U+000A>    x'",
+                                 json::parse_error&);
+        }
+    }
+
+    SECTION("many values from one stream")
+    {
+        std::string input;
+        for (int i = 0; i < 200; ++i)
+        {
+            input += R"({"id":)" + std::to_string(i) + R"(,"name":"user)" + std::to_string(i) + R"(","score":)" + std::to_string(i) + ".5}\n";
+            input += std::to_string(i * 7919) + "\n";
+        }
+
+        for (const std::size_t chunk_size : chunk_sizes())
+        {
+            CAPTURE(chunk_size)
+            chunked_streambuf buf(input, chunk_size);
+            std::istream is(&buf);
+            json j;
+            int count = 0;
+            while (!(is >> std::ws).eof())
+            {
+                is >> j;
+                if (count % 2 == 0)
+                {
+                    CHECK(j["id"] == count / 2);
+                }
+                else
+                {
+                    CHECK(j == (count / 2) * 7919);
+                }
+                ++count;
+            }
+            CHECK(count == 400);
+        }
+    }
+
+    SECTION("the stream can be used after parsing")
+    {
+        for (const std::size_t chunk_size : chunk_sizes())
+        {
+            CAPTURE(chunk_size)
+            chunked_streambuf buf(R"({"a": "some text"} trailing words 42)", chunk_size);
+            std::istream is(&buf);
+            json j;
+            is >> j;
+            CHECK(j == json({{"a", "some text"}}));
+
+            std::string word;
+            int number = 0;
+            is >> word;
+            CHECK(word == "trailing");
+            is >> word >> number;
+            CHECK(word == "words");
+            CHECK(number == 42);
+        }
+    }
+
+    SECTION("std::stringstream and std::ifstream")
+    {
+        const std::string input = R"([1, 2.5, "three", {"four": [true, null]}] 5)";
+
+        std::stringstream ss(input);
+        json j1;
+        json j2;
+        ss >> j1 >> j2;
+        CHECK(j1 == json::parse(R"([1, 2.5, "three", {"four": [true, null]}])"));
+        CHECK(j2 == 5);
+        CHECK(ss.eof());
+
+        // a file name of its own for every run: the test runs for several C++
+        // standards and configurations at the same time, in the same directory
+        std::random_device rd;
+        const std::string temp_name = "unit-stream-bulk-scan-" + std::to_string(rd()) + ".tmp";
+        const char* const filename = temp_name.c_str();
+        {
+            std::ofstream file(filename);
+            file << input;
+        }
+        {
+            std::ifstream file(filename);
+            json k1;
+            json k2;
+            file >> k1 >> k2;
+            CHECK(k1 == j1);
+            CHECK(k2 == j2);
+        }
+        static_cast<void>(std::remove(filename));
+    }
+
+    SECTION("binary formats read from a stream")
+    {
+        const json j = {{"string", std::string(300, 'x')}, {"array", {1, 2, 3}}, {"number", 1.5}};
+        const std::vector<std::uint8_t> cbor = json::to_cbor(j);
+        const std::string bytes(cbor.begin(), cbor.end());
+        for (const std::size_t chunk_size : chunk_sizes())
+        {
+            CAPTURE(chunk_size)
+            chunked_streambuf buf(bytes, chunk_size);
+            std::istream is(&buf);
+            CHECK(json::from_cbor(is) == j);
+        }
+    }
+
+#if TEST_STREAM_BULK_SCAN
+    SECTION("the adapter keeps no token unless the lexer starts one")
+    {
+        // the binary readers read through the same adapter, but never start a
+        // token; refilling the get area must then not collect the input
+        chunked_streambuf buf(std::string(1000, 'x'), 7);
+        std::istream is(&buf);
+        nlohmann::detail::input_stream_adapter ia(is);
+        for (int i = 0; i < 1000; ++i)
+        {
+            CHECK(ia.get_character() == 'x');
+        }
+
+        std::vector<char> token;
+        ia.copy_token(token, false);
+        CHECK(token.empty());
+    }
+#endif
+
+    SECTION("SAX parsing from a stream")
+    {
+        const std::string input = R"({"a": [1, "two", 3.5]} rest)";
+        for (const std::size_t chunk_size : chunk_sizes())
+        {
+            CAPTURE(chunk_size)
+            chunked_streambuf buf(input, chunk_size);
+            std::istream is(&buf);
+            json j;
+            nlohmann::detail::json_sax_dom_parser<json, nlohmann::detail::string_input_adapter_type> sax(j);
+            CHECK(json::sax_parse(is, &sax, json::input_format_t::json, false));
+            CHECK(j == json::parse(R"({"a": [1, "two", 3.5]})"));
+        }
+    }
+}
@@ -15,24 +15,6 @@
 #include <nlohmann/json.hpp>
 using nlohmann::detail::dtoa_impl::reinterpret_bits;

-#include <algorithm>
-#include <array>
-#include <cmath>
-#include <cstdint>
-#include <cstdio>
-#include <cstdlib>
-#include <iomanip>
-#include <limits>
-#include <locale>
-#include <random>
-#include <sstream>
-#include <string>
-#include <utility>
-#include <vector>
-#if defined(JSON_HAS_CPP_17)
-    #include <charconv>
-#endif
-
 namespace
 {
 float make_float(uint32_t sign_bit, uint32_t biased_exponent, uint32_t significand)
@@ -468,7 +450,7 @@ TEST_CASE("formatting")
        check_double(  1.2345e+18,   "1.2345e+18"             ); //  1.2345e+18                1.2345e+18                1.2345e18
        check_double(  1.2345e+19,   "1.2345e+19"             ); //  1.2345e+19                1.2345e+19                1.2345e19
        check_double(  1.2345e+20,   "1.2345e+20"             ); //  1.2345e+20                1.2345e+20                1.2345e20
-        check_double(  1.2345e+21,   "1.2345e+21"             ); //  1.2345e+21                1.2344999999999999e+21    1.2345e21
+        check_double(  1.2345e+21,   "1.2344999999999999e+21" ); //  1.2345e+21                1.2344999999999999e+21    1.2345e21
        check_double(  1.2345e+22,   "1.2345e+22"             ); //  1.2345e+22                1.2345e+22                1.2345e22
    }

@@ -532,327 +514,3 @@ TEST_CASE("formatting")
        check_integer(1000000000000000000LL, "1000000000000000000");
    }
 }
-
-namespace
-{
-// a small unsigned big integer (32-bit limbs, least significant first), to
-// recompute the powers of ten of the shortest double conversion
-using big = std::vector<std::uint32_t>;
-
-void big_mul_small(big& x, std::uint32_t m)
-{
-    std::uint64_t carry = 0;
-    for (auto& limb : x)
-    {
-        const std::uint64_t v = (static_cast<std::uint64_t>(limb) * m) + carry;
-        limb = static_cast<std::uint32_t>(v);
-        carry = v >> 32u;
-    }
-    if (carry != 0)
-    {
-        x.push_back(static_cast<std::uint32_t>(carry));
-    }
-}
-
-void big_div_small(big& x, std::uint32_t d)
-{
-    std::uint64_t rest = 0;
-    for (std::size_t i = x.size(); i-- > 0;)
-    {
-        const std::uint64_t v = (rest << 32u) | x[i];
-        x[i] = static_cast<std::uint32_t>(v / d);
-        rest = v % d;
-    }
-    while (!x.empty() && x.back() == 0)
-    {
-        x.pop_back();
-    }
-}
-
-std::size_t big_bit_length(const big& x)
-{
-    std::size_t n = 32 * x.size();
-    for (std::uint32_t top = x.back(); (top & 0x80000000u) == 0; top <<= 1u)
-    {
-        --n;
-    }
-    return n;
-}
-
-bool big_bit(const big& x, std::size_t i)
-{
-    return ((x[i / 32] >> (i % 32)) & 1u) != 0;
-}
-
-/// the 128 most significant bits of x (floor), shifted left if x has fewer bits
-std::pair<std::uint64_t, std::uint64_t> big_top128(const big& x)
-{
-    const std::size_t n = big_bit_length(x);
-    std::uint64_t high = 0;
-    std::uint64_t low = 0;
-    for (std::size_t k = 0; k < 128; ++k)
-    {
-        const bool bit = k < n && big_bit(x, n - 1 - k);
-        if (k < 64)
-        {
-            high = (high << 1u) | (bit ? 1u : 0u);
-        }
-        else
-        {
-            low = (low << 1u) | (bit ? 1u : 0u);
-        }
-    }
-    return {high, low};
-}
-
-/// the digits (without trailing zeros) and the decimal exponent of a
-/// representation "[-]d[.ddd][e[+-]x]"
-std::pair<std::string, int> digits_and_exponent(const std::string& s)
-{
-    std::string digits;
-    int point = -1;
-    int exponent = 0;
-    for (std::size_t i = 0; i < s.size(); ++i)
-    {
-        const char c = s[i];
-        if (c >= '0' && c <= '9')
-        {
-            digits += c;
-        }
-        else if (c == '.')
-        {
-            point = static_cast<int>(digits.size());
-        }
-        else if (c == 'e' || c == 'E')
-        {
-            exponent = std::stoi(s.substr(i + 1));
-            break;
-        }
-    }
-    int e = exponent + (point < 0 ? static_cast<int>(digits.size()) : point) - static_cast<int>(digits.size());
-    const std::size_t first = digits.find_first_not_of('0');
-    digits = first == std::string::npos ? "0" : digits.substr(first);
-    while (digits.size() > 1 && digits.back() == '0')
-    {
-        digits.pop_back();
-        ++e;
-    }
-    return {digits, e};
-}
-
-/// the correctly rounded double of a decimal text
-/// (not std::strtod: the C runtimes of some platforms, e.g. MinGW's, round
-/// some 16 and 17 digit inputs wrongly)
-double parse_double(const std::string& text)
-{
-    const nlohmann::json j = nlohmann::json::parse(text, nullptr, false);
-    // (a discarded value: out of range, as strtod's HUGE_VAL)
-    return j.is_discarded() ? std::numeric_limits<double>::infinity() : j.get<double>();
-}
-
-/// whether the decimal digits * 10^e reads back as v
-bool reads_back(const std::string& digits, int e, double v)
-{
-    const std::string text = digits + "e" + std::to_string(e);
-    // (compared bit for bit: v is positive and finite, and -Wfloat-equal)
-    return reinterpret_bits<std::uint64_t>(parse_double(text)) == reinterpret_bits<std::uint64_t>(v);
-}
-
-/// Check the representation of a positive finite double: it reads back as
-/// the same value, and no representation with fewer digits does.
-void check_shortest(double v)
-{
-    std::array<char, 33> buf{};
-    char* end = nlohmann::detail::to_chars(buf.data(), buf.data() + 32, v);
-    const std::string text(buf.data(), end);
-    CAPTURE(text)
-    CHECK(parse_double(text) == v);
-    // the layout is that of format_buffer() for the digits of Zmij
-    const auto sd = nlohmann::detail::zmij::to_shortest(reinterpret_bits<std::uint64_t>(v));
-    const std::uint64_t significand = sd.has_digit ? (sd.integral * 10) + sd.digit : sd.integral;
-    int exponent = sd.has_digit ? sd.exponent : sd.exponent + 1;
-    std::string significand_digits = std::to_string(significand);
-    while (significand_digits.size() > 1 && significand_digits.back() == '0')
-    {
-        significand_digits.pop_back();
-        ++exponent;
-    }
-    std::array<char, 64> reference{};
-    std::copy(significand_digits.begin(), significand_digits.end(), reference.begin());
-    const char* const reference_end = nlohmann::detail::dtoa_impl::format_buffer(reference.data(), static_cast<int>(significand_digits.size()), exponent, -4, 15);
-    CHECK(text == std::string(reference.data(), static_cast<std::size_t>(reference_end - reference.data())));
-    // and write_positive() is what to_chars() calls
-    std::array<char, 64> positive{};
-    const char* const positive_end = nlohmann::detail::dtoa_impl::write_positive(positive.data(), positive.data() + positive.size(), v);
-    CHECK(text == std::string(positive.data(), static_cast<std::size_t>(positive_end - positive.data())));
-    const auto de = digits_and_exponent(text);
-    const std::string& digits = de.first;
-    if (digits.size() > 1)
-    {
-        // the decimals of one digit fewer next to the value
-        // (a stream rather than snprintf("%.*e"), whose output GCC cannot bound)
-        std::ostringstream shorter;
-        shorter.imbue(std::locale::classic());
-        shorter << std::scientific << std::setprecision(static_cast<int>(digits.size()) - 2) << v;
-        const auto near = digits_and_exponent(shorter.str());
-        // as an integer with digits.size() - 1 digits
-        std::string m = near.first;
-        int e = near.second;
-        while (m.size() < digits.size() - 1)
-        {
-            m += '0';
-            --e;
-        }
-        const std::uint64_t mid = std::stoull(m);
-        for (const std::uint64_t candidate :
-                {
-                    mid - 1, mid, mid + 1
-                })
-        {
-            CAPTURE(candidate)
-            CHECK(!reads_back(std::to_string(candidate), e, v));
-        }
-    }
-    // (icpc with libstdc++ 11 defines __cpp_lib_to_chars, but has no floating-point std::to_chars)
-#if defined(JSON_HAS_CPP_17) && defined(__cpp_lib_to_chars) && !defined(__INTEL_COMPILER)
-    // the closest of the shortest representations, as std::to_chars finds it
-    std::array<char, 64> std_text{};
-    const auto r = std::to_chars(std_text.data(), std_text.data() + std_text.size(), v, std::chars_format::scientific);
-    CHECK(digits_and_exponent(std::string(std_text.data(), r.ptr)) == de);
-#endif
-}
-} // namespace
-
-TEST_CASE("shortest digits of doubles")
-{
-    SECTION("powers of ten")
-    {
-        // the 128-bit significands of 10^k, rounded down, recomputed
-        for (int k = -342; k <= 341; ++k)
-        {
-            CAPTURE(k)
-            big x{1};
-            if (k >= 0)
-            {
-                for (int i = 0; i < k; ++i)
-                {
-                    big_mul_small(x, 10);
-                }
-            }
-            else
-            {
-                // floor(2^b / 10^-k) for a b that leaves more than 128 bits
-                const int b = 128 + 64 + (4 * -k);
-                x.assign(static_cast<std::size_t>(b / 32) + 1, 0);
-                x.back() = 1u << (b % 32);
-                for (int i = 0; i < -k; ++i)
-                {
-                    big_div_small(x, 10);
-                }
-            }
-            const auto expected = big_top128(x);
-            const auto actual = nlohmann::detail::zmij::pow10(k);
-            CHECK(actual.high == expected.first);
-            CHECK(actual.low == expected.second);
-        }
-    }
-
-    SECTION("boundary values")
-    {
-        for (const double v :
-                {
-                    std::numeric_limits<double>::min(), std::numeric_limits<double>::max(), std::numeric_limits<double>::denorm_min(),
-                    std::nextafter(std::numeric_limits<double>::min(), 0.0), 1.0, 2.0, 0.1, 0.3, 1e21, 1e22, 1e23, 5e-324, 9007199254740993.0,
-                    1.2345e+21, 2.2250738585072014e-308, 1.7976931348623157e308, 4.9406564584124654e-324, 123456789012345680.0
-                })
-        {
-            check_shortest(v);
-        }
-        // all powers of two (their rounding interval is narrower below)
-        for (int e = -1074; e <= 1023; ++e)
-        {
-            check_shortest(std::ldexp(1.0, e));
-        }
-        // powers of ten and their neighbors
-        for (int e = -323; e <= 308; ++e)
-        {
-            const double p = std::strtod(("1e" + std::to_string(e)).c_str(), nullptr);
-            check_shortest(p);
-            check_shortest(std::nextafter(p, 0.0));
-            check_shortest(std::nextafter(p, std::numeric_limits<double>::infinity()));
-        }
-    }
-
-    SECTION("random doubles")
-    {
-        std::mt19937_64 rng(5295); // NOLINT(cert-msc32-c,cert-msc51-cpp,bugprone-random-generator-seed): reproducible
-        for (int i = 0; i < 100000; ++i)
-        {
-            const std::uint64_t bits = rng() & 0x7FFFFFFFFFFFFFFFu;
-            const auto v = reinterpret_bits<double>(bits);
-            if (std::isfinite(v) && bits != 0)
-            {
-                check_shortest(v);
-            }
-        }
-    }
-}
-
-TEST_CASE("choice of the conversion")
-{
-    using nlohmann::detail::dtoa_impl::is_binary64;
-
-    SECTION("by the format of the type")
-    {
-        // Zmij needs binary64 numbers; everything else uses Grisu2
-        static_assert(!is_binary64<float>::value, "float is not binary64");
-        static_assert(is_binary64<double>::value == (std::numeric_limits<double>::is_iec559 && std::numeric_limits<double>::digits == 53),
-                      "double is binary64 where it is IEEE 754 with 53 digits");
-        static_assert(!is_binary64<int>::value, "integers are not binary64");
-        static_assert(is_binary64<long double>::value == (std::numeric_limits<long double>::is_iec559 && std::numeric_limits<long double>::digits == 53 && sizeof(long double) == 8),
-                      "long double is binary64 where it has the format of a double");
-        CHECK(!is_binary64<float>::value);
-        CHECK(is_binary64<double>::value);
-    }
-
-    SECTION("float: Grisu2, double: Zmij")
-    {
-        // 5.3165205877497296e+16 is one of the doubles for which Grisu2 does not find the shortest digits
-        constexpr double value = 5.3165205877497296e+16;
-        std::array<char, 64> buf{};
-        const char* const last = buf.data() + buf.size();
-
-        char* end = nlohmann::detail::dtoa_impl::write_positive(buf.data(), last, value);
-        CHECK(std::string(buf.data(), end) == "5.31652058774973e+16");
-        end = nlohmann::detail::dtoa_impl::write_positive_grisu2(buf.data(), last, value);
-        CHECK(std::string(buf.data(), end) == "5.3165205877497296e+16");
-
-        constexpr float f = 1.1754944e-38f;
-        end = nlohmann::detail::dtoa_impl::write_positive(buf.data(), last, f);
-        const std::string dispatched(buf.data(), end);
-        end = nlohmann::detail::dtoa_impl::write_positive_grisu2(buf.data(), last, f);
-        CHECK(dispatched == std::string(buf.data(), end));
-    }
-
-    SECTION("long double with the format of a double: Zmij")
-    {
-        // (on platforms where long double is wider, Grisu2 does not apply either: the snprintf fallback does)
-        // (constant on a given platform)
-        DOCTEST_MSVC_SUPPRESS_WARNING_PUSH
-        DOCTEST_MSVC_SUPPRESS_WARNING(4127)
-        if (std::numeric_limits<long double>::digits == 53 && std::numeric_limits<long double>::is_iec559)
-        {
-            using long_double_json = nlohmann::json::with_float_t<long double>;
-            for (const double d :
-                    {
-                        5.3165205877497296e+16, 1.0, 0.1, 123456.789, 2.2250738585072014e-308, 1.7976931348623157e+308, -5.3165205877497296e+16
-                    })
-            {
-                CAPTURE(d)
-                CHECK(long_double_json(static_cast<long double>(d)).dump() == nlohmann::json(d).dump());
-            }
-            CHECK(long_double_json(5.3165205877497296e+16L).dump() == "5.31652058774973e+16");
-        }
-        DOCTEST_MSVC_SUPPRESS_WARNING_POP
-    }
-}
Author	SHA1	Message	Date
Niels Lohmann	f13fbd2577	Add benchmarks for parsing from a FILE* and for many values from a stream ParseFILE/* parses the nativejson-benchmark files from a FILE, and ParseStreamValues/ reads 10,000 small values from one std::istringstream with operator>> (NDJSON objects and plain numbers), which measures the per-value cost of stream input. Signed-off-by: Niels Lohmann <mail@nlohmann.me>	2026-10-14 17:34:01 +02:00
Niels Lohmann	c391abccb1	Lock a FILE once per parse instead of once per character Parsing from a FILE* reads one character at a time with std::fgetc, which locks and unlocks the FILE object for every character. file_input_adapter now locks the file once when it is created and unlocks it when it is destroyed - also when parsing throws - and reads with the unlocked stdio functions in between: flockfile/getc_unlocked/funlockfile with glibc, Apple, Android, and the BSDs, and _lock_file/_fgetc_nolock/_unlock_file with the Microsoft C runtime. Other C libraries keep std::fgetc. The lock is recursive, so fread() in the binary readers and stdio calls of a SAX handler or parser callback on the same thread keep working. On an Apple M1 Max, parsing from a FILE* is 2.9 to 4.0 times as fast (twitter.json 14.3 -> 4.1 ms, citm_catalog.json 35.4 -> 8.8 ms); with glibc, whose locking is cheaper, 1.1 to 1.3 times. The values and the position of the file after parsing are unchanged. Other threads that use the same FILE object now wait until parsing is done instead of interleaving their reads with the parser's. JSON_DISABLE_UNLOCKED_FILE_IO restores std::fgetc, for programs in which a SAX handler waits for another thread that uses the same FILE. The new tests check from a second thread that the lock is released after success and after a parse error, and run again with the macro. Signed-off-by: Niels Lohmann <mail@nlohmann.me>	2026-10-14 17:34:00 +02:00
Niels Lohmann	d5631dccbd	Scan the get area of an input stream in bulk Parsing from a std::istream read one character at a time through the streambuf, so none of the parser's fast paths applied: it was 1.8 to 2.5 times slower than reading the file into a string and parsing that. input_stream_adapter now exposes the streambuf's get area (gptr() to egptr()) to the lexer as a window. The protected get-area members are reached through member pointers formed in a class derived from std::streambuf, which is ordinary, standard-conforming member access. The lexer scans the window with the same bulk paths as a string, and asks the streambuf for the next character as before when the window is used up. Nothing is read ahead, copied, or put back, so the stream is left exactly where it was left before, with and without JSON_PRECISE_STREAM_POSITION, and a streambuf without a get area is still read one character at a time. The adapter also keeps the current token for error messages as a pointer into the get area, and copies it out only before the get area is refilled, instead of the lexer copying every character. On an Apple M1 Max (Apple Clang, -O3), parsing from an std::ifstream is 1.6 to 2.1 times as fast (twitter.json 4.08 -> 2.30 ms, citm_catalog.json 8.75 -> 4.08 ms), and reading 100,000 small values with operator>> 1.4 (objects) to 4.0 (integers) times as fast. With GCC 13 and libstdc++ on x86-64 Linux, std::ifstream is 1.5 to 2.2 times as fast. Parsing from a stream is now within 11 to 18 % of reading the file into a string first. JSON_DISABLE_STREAM_BULK_SCAN restores reading one character at a time, for streambufs that do not follow the usual get-area contract. The new tests compare every observable result (values, exception messages, stream state, remaining characters) for get areas of 1 to 4096 bytes against a streambuf without a get area, and run again with the macro and with JSON_PRECISE_STREAM_POSITION. Signed-off-by: Niels Lohmann <mail@nlohmann.me>	2026-10-14 17:26:38 +02:00
Niels Lohmann	80d00eda50	Let the lexer's bulk fast paths run on a window of the input The SWAR string scan, the bulk number scan, and the indentation skip were only enabled for adapters that support seeking (contiguous random-access input), because they rely on the lazy token and position tracking that reconstructs both from the consumed input on demand. This decouples the bulk paths from seeking, so that an adapter can expose a contiguous block that is only a window into its input (bulk_window): - bulk_consume() does the bookkeeping that get() would have done for the skipped characters when token and position are tracked eagerly. - A number that reaches the end of a window is finished character by character, because it may continue after the window. - After a bulk-scanned number, a window adapter reads the terminating character and ungets it, as scan_number() does, so that the input handed back to the user is consumed exactly as before. - An adapter can keep the current token itself (supports_token_tracking, begin_token(), mark_token_start(), copy_token()) so the lexer need not copy every character for its error messages. No adapter declares any of this yet, so the behavior is unchanged. Signed-off-by: Niels Lohmann <mail@nlohmann.me>	2026-10-14 17:13:58 +02:00