Merge branch 'develop' into claude/todo-191-plan-508110

Conflicts: none textual. Follow-up fixes for develop's changes: - docs/mkdocs/docs/api/ordered_map/index.md: develop's new paragraph (#5609) was written for api/ordered_map.md; fixed its relative ordered_json.md link for the page's new location, plus two pre-existing links from an earlier merge (ordered_json.md, features/object_order.md) - tools/api_checker/api_surface.json: regenerated with libclang 18.1.1 on Linux (swap() noexcept now includes json_base_class_t; new integral-key contains/count/find/value overloads) Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-01 04:00:31 +00:00 · 2026-09-30 20:36:12 +02:00 · 2026-09-28 22:22:46 +02:00 · 2026-09-28 18:42:34 +02:00 · 2026-09-27 21:37:14 +02:00 · 2026-09-27 18:09:03 +02:00
136 changed files with 73393 additions and 2616 deletions
@@ -0,0 +1,81 @@
+name: "Check API documentation"
+
+on:
+  pull_request:
+
+permissions:
+  contents: read
+
+jobs:
+  check_api_docs:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Harden Runner
+        uses: step-security/harden-runner@bf7454d06d71f1098171f2acdf0cd4708d7b5920 # v2.20.0
+        with:
+          egress-policy: audit
+
+      - name: Checkout pull request
+        uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
+
+      - name: Install clang
+        # Used only as a subprocess for `clang++ -E -v` system-include-path discovery in
+        # extract_api.py; it does not need to version-match the pinned libclang pip wheel
+        # below, which does the actual AST parsing. Do not "fix" this to be version-matched.
+        run: sudo apt-get update && sudo apt-get install -y clang
+
+      - name: Install Python dependencies
+        run: pip install -r tools/api_checker/requirements.txt
+
+      - name: Extract API and regenerate the committed surface file
+        run: |
+          python3 tools/api_checker/extract_api.py \
+            --header include/nlohmann/json.hpp \
+            --include include \
+            --output /tmp/api_snapshot.json \
+            --surface-output tools/api_checker/api_surface.json
+
+      - name: "Check API documentation (Phase 1: advisory)"
+        # Surfaces missing/broken @sa links without failing the job while the backlog from the
+        # initial AST-based rollout is burned down. See tools/api_checker/POLICY.md and the PR
+        # that introduced this workflow for the two-phase rollout plan.
+        continue-on-error: true
+        run: |
+          python3 tools/api_checker/check_docs.py \
+            --snapshot /tmp/api_snapshot.json
+
+      - name: Check macro documentation (advisory only)
+        # Cross-checks docs/mkdocs/docs/api/macros/ pages against #define sites. Only checks the
+        # documented-macro-still-exists direction; never blocks CI. See POLICY.md.
+        run: python3 tools/api_checker/check_macros.py
+
+      - name: Check for uncommitted API surface changes
+        id: diff
+        run: |
+          mkdir -p ${{ github.workspace }}/patch
+          git diff --patch --no-color -- tools/api_checker/api_surface.json > ${{ github.workspace }}/patch/api_surface.patch
+          if [ -s ${{ github.workspace }}/patch/api_surface.patch ]; then
+            echo "tools/api_checker/api_surface.json is out of date. Diff:"
+            cat ${{ github.workspace }}/patch/api_surface.patch
+            echo "has_diff=true" >> "$GITHUB_OUTPUT"
+          else
+            echo "has_diff=false" >> "$GITHUB_OUTPUT"
+          fi
+
+      # Uploaded so contributors can fix their PR with `git apply api_surface.patch`
+      # instead of installing libclang locally.
+      - name: Upload patch
+        if: steps.diff.outputs.has_diff == 'true'
+        uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
+        with:
+          name: api-surface-patch
+          path: patch/api_surface.patch
+
+      - name: Fail if API surface file is not up to date
+        # Unlike the doc-backlog check above, this is purely mechanical regeneration with no
+        # backlog to phase in -- blocking from the start, matching check_amalgamation.yml's
+        # precedent. Contributors who add/remove/rename public API must regenerate and commit
+        # tools/api_checker/api_surface.json as part of their PR.
+        if: steps.diff.outputs.has_diff == 'true'
+        run: exit 1
@@ -3,6 +3,7 @@
 *.gcno
 *.gcda
 .DS_Store
+__pycache__/

 /.idea
 /cmake-build-*
@@ -43,5 +44,9 @@ venv

 nlohmann_json.spdx

+# api_checker: ephemeral, location/doc-status-sensitive working file (not the committed
+# release-tracking artifact -- see tools/api_checker/api_surface.json for that)
+/tools/api_checker/api_snapshot.json
+
 # Bazel-related
 MODULE.bazel.lock
@@ -106,7 +106,7 @@ Thanks everyone!

 :books: If you want to **learn more** about how to use the library, check out the rest of the [**README**](#examples), have a look at [**code examples**](https://github.com/nlohmann/json/tree/develop/docs/mkdocs/docs/examples), or browse through the [**help pages**](https://json.nlohmann.me).

-:construction: If you want to understand the **API** better, check out the [**API Reference**](https://json.nlohmann.me/api/basic_json/) or have a look at the [quick reference](#quick-reference) below.
+:construction: If you want to understand the **API** better, check out the [**API Reference**](https://json.nlohmann.me/api/basic_json/) or have a look at the [quick reference](#quick-reference) below. The public API surface is derived mechanically and checked for documentation coverage by the tooling in [`tools/api_checker/`](tools/api_checker/), whose [POLICY.md](tools/api_checker/POLICY.md) defines what counts as public API and what stability is guaranteed.

 :bug: If you found a **bug**, please check the [**FAQ**](https://json.nlohmann.me/home/faq/) if it is a known issue or the result of a design decision. Please also have a look at the [**issue list**](https://github.com/nlohmann/json/issues) before you [**create a new issue**](https://github.com/nlohmann/json/issues/new/choose). Please provide as much information as possible to help us understand and reproduce your issue.

@@ -1395,7 +1395,7 @@ THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR I
 - 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 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">

@@ -420,7 +420,9 @@ basic_json(basic_json&& other) noexcept;
 1. Since version 1.0.0.
 2. Since version 1.0.0.
 3. Since version 2.1.0.
-4. Since version 3.2.0.
+4. Since version 3.2.0. Also initializes the position reported by
+   [`start_pos()`](start_pos.md)/[`end_pos()`](end_pos.md) from `val` when
+   [`JSON_DIAGNOSTIC_POSITIONS`](../macros/json_diagnostic_positions.md) is enabled, since version 3.12.0.
 5. Since version 1.0.0.
 6. Since version 1.0.0.
 7. Since version 1.0.0. Fixed in version 3.13.0 to also check the iterator range for binary values; before, a range
@@ -0,0 +1,38 @@
+# <small>nlohmann::basic_json::</small>bjdata_version_t
+
+```cpp
+enum class bjdata_version_t
+{
+    draft2,
+    draft3,
+};
+```
+
+This enumeration is used in the [`to_bjdata`](to_bjdata.md) function to choose which draft version of
+the BJData specification to encode ND-array extensions for:
+
+draft2
+:   encode using the BJData Draft 2 ND-array format
+
+draft3
+:   encode using the BJData Draft 3 ND-array format
+
+## Examples
+
+??? example
+
+    The example shows how `bjdata_version_t` selects the BJData draft used by `to_bjdata`.
+
+    ```cpp
+    --8<-- "examples/bjdata_version_t.cpp"
+    ```
+
+    Output:
+
+    ```
+    --8<-- "examples/bjdata_version_t.output"
+    ```
+
+## Version history
+
+- Added in version 3.12.0.
@@ -0,0 +1,32 @@
+# <small>nlohmann::basic_json::</small>initializer_list_t
+
+```cpp
+using initializer_list_t = std::initializer_list<detail::json_ref<basic_json>>;
+```
+
+The type used for the initializer-list [constructor](basic_json.md) (overload 5) and for functions
+such as [`operator=`](operator=.md) that accept a braced-init-list of JSON values. Each element wraps a
+`basic_json` value or something convertible to one, deferring the decision of whether the list should be
+parsed as a JSON array or a JSON object to the constructor itself.
+
+See the [constructor](basic_json.md) documentation for how `initializer_list_t` values are interpreted.
+
+## Examples
+
+??? example
+
+    The example shows how an `initializer_list_t` is used to construct a JSON value.
+
+    ```cpp
+    --8<-- "examples/initializer_list_t.cpp"
+    ```
+
+    Output:
+
+    ```
+    --8<-- "examples/initializer_list_t.output"
+    ```
+
+## Version history
+
+- Since version 1.0.0.
@@ -0,0 +1,31 @@
+# <small>nlohmann::basic_json::</small>json_sax_t
+
+```cpp
+using json_sax_t = json_sax<basic_json>;
+```
+
+The [`json_sax`](../json_sax/index.md) interface bound to this `basic_json` specialization, i.e. with
+`BasicJsonType` fixed to `basic_json`. Used as the SAX interface type by [`sax_parse`](sax_parse.md) and
+other SAX-based parsing functions.
+
+See [`nlohmann::json_sax`](../json_sax/index.md) for more information.
+
+## Examples
+
+??? example
+
+    The example shows the type `json_sax_t`.
+
+    ```cpp
+    --8<-- "examples/json_sax_t.cpp"
+    ```
+
+    Output:
+
+    ```
+    --8<-- "examples/json_sax_t.output"
+    ```
+
+## Version history
+
+- Added in version 3.2.0.
@@ -23,10 +23,9 @@ type to use.
 ## Template parameters

 `NumberFloatType`
-:   the type to store floating-point numbers. The parser converts `#!cpp float`, `#!cpp double`, and a
-    `#!cpp long double` that is IEEE 754 binary64 itself and other `#!cpp long double` formats with
-    `#!cpp std::from_chars` or `#!cpp std::strtold`, and serialization falls back to `#!cpp std::snprintf`, so the
-    type must be `#!cpp float`, `#!cpp double`, or `#!cpp long double`. 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).
@@ -51,3 +51,5 @@ Linear.
 ## Version history

 - Added in version 1.0.0.
+- The `noexcept` specification was extended to also depend on
+  [`json_base_class_t`](json_base_class_t.md)'s move-assignment in version 3.11.3.
@@ -85,3 +85,8 @@ Linear in the size of the JSON value.
 - Since version 1.0.0.
 - Macros `JSON_EXPLICIT`/[`JSON_USE_IMPLICIT_CONVERSIONS`](../macros/json_use_implicit_conversions.md) added
  in version 3.9.0.
+- The exclusion of `std::any` from this conversion became conditional on
+  [`JSON_HAS_STATIC_RTTI`](../macros/json_has_static_rtti.md) in version 3.11.3.
+- `std::optional<T>` excluded from this conversion in version 3.13.0; use
+  [`get<std::optional<T>>()`](get.md)/[`get_to()`](get_to.md) instead (see
+  [Converting values](../../features/conversions.md)).
@@ -0,0 +1,32 @@
+# <small>nlohmann::byte_container_with_subtype::</small>container_type
+
+```cpp
+using container_type = BinaryType;
+```
+
+The type of the underlying binary container, forwarded from the `BinaryType` template parameter that
+`byte_container_with_subtype` is instantiated with. `byte_container_with_subtype` publicly inherits from
+`container_type`.
+
+See [`basic_json::binary_t`](../basic_json/binary_t.md) for the type typically used to instantiate
+`BinaryType`.
+
+## Examples
+
+??? example
+
+    The example shows the type `container_type`.
+
+    ```cpp
+    --8<-- "examples/byte_container_with_subtype__container_type.cpp"
+    ```
+
+    Output:
+
+    ```
+    --8<-- "examples/byte_container_with_subtype__container_type.output"
+    ```
+
+## Version history
+
+- Since version 3.8.0.
@@ -0,0 +1,45 @@
+# <small>nlohmann::byte_container_with_subtype::</small>operator==
+
+```cpp
+bool operator==(const byte_container_with_subtype& rhs) const;
+```
+
+Compares two `byte_container_with_subtype` values for equality by comparing the underlying binary
+container, the subtype, and whether a subtype is set.
+
+## Parameters
+
+`rhs` (in)
+:   value to compare `*this` against
+
+## Return value
+
+whether `*this` and `rhs` are equal
+
+## Exception safety
+
+No-throw guarantee: this function never throws exceptions.
+
+## Complexity
+
+Linear in the size of the underlying binary container.
+
+## Examples
+
+??? example
+
+    The example demonstrates comparing `byte_container_with_subtype` values.
+
+    ```cpp
+    --8<-- "examples/byte_container_with_subtype__operator_eq.cpp"
+    ```
+
+    Output:
+
+    ```
+    --8<-- "examples/byte_container_with_subtype__operator_eq.output"
+    ```
+
+## Version history
+
+- Since version 3.8.0.
@@ -0,0 +1,45 @@
+# <small>nlohmann::byte_container_with_subtype::</small>operator!=
+
+```cpp
+bool operator!=(const byte_container_with_subtype& rhs) const;
+```
+
+Compares two `byte_container_with_subtype` values for inequality. Implemented as the negation of
+[`operator==`](operator_eq.md).
+
+## Parameters
+
+`rhs` (in)
+:   value to compare `*this` against
+
+## Return value
+
+whether `*this` and `rhs` are not equal
+
+## Exception safety
+
+No-throw guarantee: this function never throws exceptions.
+
+## Complexity
+
+Linear in the size of the underlying binary container.
+
+## Examples
+
+??? example
+
+    The example demonstrates comparing `byte_container_with_subtype` values.
+
+    ```cpp
+    --8<-- "examples/byte_container_with_subtype__operator_ne.cpp"
+    ```
+
+    Output:
+
+    ```
+    --8<-- "examples/byte_container_with_subtype__operator_ne.output"
+    ```
+
+## Version history
+
+- Since version 3.8.0.
@@ -0,0 +1,28 @@
+# <small>nlohmann::byte_container_with_subtype::</small>subtype_type
+
+```cpp
+using subtype_type = std::uint64_t;
+```
+
+The type used to store the optional binary subtype tag. See [`subtype`](subtype.md) and
+[`set_subtype`](set_subtype.md).
+
+## Examples
+
+??? example
+
+    The example shows the type `subtype_type`.
+
+    ```cpp
+    --8<-- "examples/byte_container_with_subtype__subtype_type.cpp"
+    ```
+
+    Output:
+
+    ```
+    --8<-- "examples/byte_container_with_subtype__subtype_type.output"
+    ```
+
+## Version history
+
+- Since version 3.8.0.
@@ -0,0 +1,30 @@
+# <small>nlohmann::json_sax::</small>binary_t
+
+```cpp
+using binary_t = typename BasicJsonType::binary_t;
+```
+
+The type used by the [`binary`](binary.md) callback for JSON binary values, forwarded from the
+`BasicJsonType` template parameter.
+
+See [`basic_json::binary_t`](../basic_json/binary_t.md) for more information.
+
+## Examples
+
+??? example
+
+    The example shows the type `binary_t` and its relation to `basic_json::binary_t`.
+
+    ```cpp
+    --8<-- "examples/json_sax__binary_t.cpp"
+    ```
+
+    Output:
+
+    ```
+    --8<-- "examples/json_sax__binary_t.output"
+    ```
+
+## Version history
+
+- Added in version 3.8.0.
@@ -0,0 +1,33 @@
+# <small>nlohmann::json_sax::</small>json_sax
+
+```cpp
+// (1)
+json_sax() = default;
+
+// (2)
+json_sax(const json_sax&) = default;
+
+// (3)
+json_sax(json_sax&&) noexcept = default;
+```
+
+1. Default constructor.
+2. Copy constructor.
+3. Move constructor.
+
+`json_sax` is a pure abstract base class with no data members of its own, so all three constructors are
+defaulted and only exist to make derived SAX consumers explicitly copyable/movable.
+
+## Exception safety
+
+No-throw guarantee: none of these constructors throw exceptions.
+
+## Complexity
+
+Constant.
+
+<!-- NOLINT Examples -->
+
+## Version history
+
+- Added in version 3.2.0.
@@ -0,0 +1,30 @@
+# <small>nlohmann::json_sax::</small>number_float_t
+
+```cpp
+using number_float_t = typename BasicJsonType::number_float_t;
+```
+
+The type used by the [`number_float`](number_float.md) callback for JSON floating-point numbers,
+forwarded from the `BasicJsonType` template parameter.
+
+See [`basic_json::number_float_t`](../basic_json/number_float_t.md) for more information.
+
+## Examples
+
+??? example
+
+    The example shows the type `number_float_t` and its relation to `basic_json::number_float_t`.
+
+    ```cpp
+    --8<-- "examples/json_sax__number_float_t.cpp"
+    ```
+
+    Output:
+
+    ```
+    --8<-- "examples/json_sax__number_float_t.output"
+    ```
+
+## Version history
+
+- Added in version 3.2.0.
@@ -0,0 +1,30 @@
+# <small>nlohmann::json_sax::</small>number_integer_t
+
+```cpp
+using number_integer_t = typename BasicJsonType::number_integer_t;
+```
+
+The type used by the [`number_integer`](number_integer.md) callback for JSON integer numbers, forwarded
+from the `BasicJsonType` template parameter.
+
+See [`basic_json::number_integer_t`](../basic_json/number_integer_t.md) for more information.
+
+## Examples
+
+??? example
+
+    The example shows the type `number_integer_t` and its relation to `basic_json::number_integer_t`.
+
+    ```cpp
+    --8<-- "examples/json_sax__number_integer_t.cpp"
+    ```
+
+    Output:
+
+    ```
+    --8<-- "examples/json_sax__number_integer_t.output"
+    ```
+
+## Version history
+
+- Added in version 3.2.0.
@@ -0,0 +1,30 @@
+# <small>nlohmann::json_sax::</small>number_unsigned_t
+
+```cpp
+using number_unsigned_t = typename BasicJsonType::number_unsigned_t;
+```
+
+The type used by the [`number_unsigned`](number_unsigned.md) callback for JSON unsigned integer numbers,
+forwarded from the `BasicJsonType` template parameter.
+
+See [`basic_json::number_unsigned_t`](../basic_json/number_unsigned_t.md) for more information.
+
+## Examples
+
+??? example
+
+    The example shows the type `number_unsigned_t` and its relation to `basic_json::number_unsigned_t`.
+
+    ```cpp
+    --8<-- "examples/json_sax__number_unsigned_t.cpp"
+    ```
+
+    Output:
+
+    ```
+    --8<-- "examples/json_sax__number_unsigned_t.output"
+    ```
+
+## Version history
+
+- Added in version 3.2.0.
@@ -0,0 +1,29 @@
+# <small>nlohmann::json_sax::</small>operator=
+
+```cpp
+// (1)
+json_sax& operator=(const json_sax&) = default;
+
+// (2)
+json_sax& operator=(json_sax&&) noexcept = default;
+```
+
+1. Copy assignment operator.
+2. Move assignment operator.
+
+`json_sax` is a pure abstract base class with no data members of its own, so both assignment operators
+are defaulted and only exist to make derived SAX consumers explicitly copy-/move-assignable.
+
+## Exception safety
+
+No-throw guarantee: neither operator throws exceptions.
+
+## Complexity
+
+Constant.
+
+<!-- NOLINT Examples -->
+
+## Version history
+
+- Added in version 3.2.0.
@@ -0,0 +1,30 @@
+# <small>nlohmann::json_sax::</small>string_t
+
+```cpp
+using string_t = typename BasicJsonType::string_t;
+```
+
+The type used by the [`string`](string.md) and [`key`](key.md) callbacks for JSON strings and object
+keys, forwarded from the `BasicJsonType` template parameter.
+
+See [`basic_json::string_t`](../basic_json/string_t.md) for more information.
+
+## Examples
+
+??? example
+
+    The example shows the type `string_t` and its relation to `basic_json::string_t`.
+
+    ```cpp
+    --8<-- "examples/json_sax__string_t.cpp"
+    ```
+
+    Output:
+
+    ```
+    --8<-- "examples/json_sax__string_t.output"
+    ```
+
+## Version history
+
+- Added in version 3.2.0.
@@ -0,0 +1,22 @@
+# <small>nlohmann::json_sax::</small>~json_sax
+
+```cpp
+virtual ~json_sax() = default;
+```
+
+Destructor. Virtual to allow proper destruction of derived SAX consumer classes through a
+pointer/reference to `json_sax`.
+
+## Exception safety
+
+No-throw guarantee: this destructor never throws exceptions.
+
+## Complexity
+
+Constant.
+
+<!-- NOLINT Examples -->
+
+## Version history
+
+- Added in version 3.2.0.
@@ -8,16 +8,16 @@ This type preserves the insertion order of object keys.

 ## Iterator invalidation

-The type is based on [`ordered_map`](ordered_map.md) which in turn uses a `std::vector` to store object elements.
+The type is based on [`ordered_map`](ordered_map/index.md) which in turn uses a `std::vector` to store object elements.
 Therefore, adding object elements can yield a reallocation in which case all iterators (including the
 [`end()`](basic_json/end.md) iterator) and all references to the elements are invalidated. Also, any iterator or
 reference after the insertion point will point to the same index, which is now a different value.

 ## Complexity

-[`ordered_map`](ordered_map.md) has no lookup index: every key-based object operation is a linear scan, so building or
+[`ordered_map`](ordered_map/index.md) has no lookup index: every key-based object operation is a linear scan, so building or
 parsing an object of `n` keys costs O(n²) rather than O(n log n). See
-[`ordered_map` complexity](ordered_map.md#complexity) for the per-operation table and for measured numbers.
+[`ordered_map` complexity](ordered_map/index.md#complexity) for the per-operation table and for measured numbers.

 ## Examples

@@ -37,7 +37,7 @@ parsing an object of `n` keys costs O(n²) rather than O(n log n). See

 ## See also

- [ordered_map](ordered_map.md)
+- [ordered_map](ordered_map/index.md)
 - [Object Order](../features/object_order.md)

 ## Version history
@@ -0,0 +1,28 @@
+# <small>nlohmann::ordered_map::</small>Container
+
+```cpp
+using Container = std::vector<std::pair<const Key, T>, Allocator>;
+```
+
+The base container type that `ordered_map` publicly inherits from. Elements are stored in insertion
+order as `#!cpp std::pair<const Key, T>` entries in a `std::vector`.
+
+## Examples
+
+??? example
+
+    The example shows the type `Container`.
+
+    ```cpp
+    --8<-- "examples/ordered_map__Container.cpp"
+    ```
+
+    Output:
+
+    ```
+    --8<-- "examples/ordered_map__Container.output"
+    ```
+
+## Version history
+
+- Added in version 3.9.0 to implement [`nlohmann::ordered_json`](../ordered_json.md).
@@ -0,0 +1,61 @@
+# <small>nlohmann::ordered_map::</small>at
+
+```cpp
+// (1)
+T& at(const key_type& key);
+const T& at(const key_type& key) const;
+
+// (2)
+template<class KeyType>
+T& at(KeyType&& key);
+template<class KeyType>
+const T& at(KeyType&& key) const;
+```
+
+1. Returns a reference to the value mapped to `key`.
+2. Same as (1), but for any `KeyType` comparable to `key_type` via [`key_compare`](key_compare.md)
+   (heterogeneous lookup, e.g. looking up by a `#!cpp const char*` without constructing a temporary
+   `key_type`). Only participates in overload resolution if `KeyType` is usable as a key type.
+
+## Template parameters
+
+`KeyType`
+:   a type comparable to `key_type` via [`key_compare`](key_compare.md)
+
+## Parameters
+
+`key` (in)
+:   key of the element to find
+
+## Return value
+
+reference to the mapped value of the element with key equal to `key`
+
+## Exceptions
+
+Throws `std::out_of_range` if no element with key `key` exists.
+
+## Complexity
+
+Linear in the number of elements.
+
+## Examples
+
+??? example
+
+    The example shows how `at` is used.
+
+    ```cpp
+    --8<-- "examples/ordered_map__at.cpp"
+    ```
+
+    Output:
+
+    ```
+    --8<-- "examples/ordered_map__at.output"
+    ```
+
+## Version history
+
+- Added in version 3.9.1 to implement [`nlohmann::ordered_json`](../ordered_json.md).
+- Overload (2) added in version 3.11.0.
@@ -0,0 +1,53 @@
+# <small>nlohmann::ordered_map::</small>count
+
+```cpp
+// (1)
+size_type count(const key_type& key) const;
+
+// (2)
+template<class KeyType>
+size_type count(KeyType&& key) const;
+```
+
+1. Returns the number of elements with key equal to `key` (0 or 1, since keys are unique).
+2. Same as (1), but for any `KeyType` comparable to `key_type` via [`key_compare`](key_compare.md)
+   (heterogeneous lookup). Only participates in overload resolution if `KeyType` is usable as a key type.
+
+## Template parameters
+
+`KeyType`
+:   a type comparable to `key_type` via [`key_compare`](key_compare.md)
+
+## Parameters
+
+`key` (in)
+:   key of the elements to count
+
+## Return value
+
+number of elements with key equal to `key` (0 or 1)
+
+## Complexity
+
+Linear in the number of elements.
+
+## Examples
+
+??? example
+
+    The example shows how `count` is used.
+
+    ```cpp
+    --8<-- "examples/ordered_map__count.cpp"
+    ```
+
+    Output:
+
+    ```
+    --8<-- "examples/ordered_map__count.output"
+    ```
+
+## Version history
+
+- Added in version 3.9.1 to implement [`nlohmann::ordered_json`](../ordered_json.md).
+- Overload (2) added in version 3.11.0.
@@ -0,0 +1,58 @@
+# <small>nlohmann::ordered_map::</small>emplace
+
+```cpp
+// (1)
+std::pair<iterator, bool> emplace(const key_type& key, T&& t);
+
+// (2)
+template<class KeyType>
+std::pair<iterator, bool> emplace(KeyType&& key, T&& t);
+```
+
+1. Inserts `#!cpp {key, t}` if no element with an equal key already exists (per [`key_compare`](key_compare.md)),
+   appending it at the end to preserve insertion order. If an equal key already exists, does nothing.
+2. Same as (1), but for any `KeyType` comparable to `key_type` via [`key_compare`](key_compare.md)
+   (heterogeneous lookup). Only participates in overload resolution if `KeyType` is usable as a key type.
+
+## Template parameters
+
+`KeyType`
+:   a type comparable to `key_type` via [`key_compare`](key_compare.md)
+
+## Parameters
+
+`key` (in)
+:   key of the element to insert
+
+`t` (in)
+:   value of the element to insert
+
+## Return value
+
+pair of an iterator to the (possibly newly inserted) element, and a `bool` that is `true` if insertion
+took place and `false` if an element with an equal key already existed
+
+## Complexity
+
+Linear in the number of elements.
+
+## Examples
+
+??? example
+
+    The example shows how `emplace` is used.
+
+    ```cpp
+    --8<-- "examples/ordered_map__emplace.cpp"
+    ```
+
+    Output:
+
+    ```
+    --8<-- "examples/ordered_map__emplace.output"
+    ```
+
+## Version history
+
+- Added in version 3.9.0 to implement [`nlohmann::ordered_json`](../ordered_json.md).
+- Overload (2) added in version 3.11.0.
@@ -0,0 +1,75 @@
+# <small>nlohmann::ordered_map::</small>erase
+
+```cpp
+// (1)
+size_type erase(const key_type& key);
+
+// (2)
+template<class KeyType>
+size_type erase(KeyType&& key);
+
+// (3)
+iterator erase(iterator pos);
+
+// (4)
+iterator erase(iterator first, iterator last);
+```
+
+1. Removes the element with key equal to `key`, if any, preserving the relative order of the remaining
+   elements.
+2. Same as (1), but for any `KeyType` comparable to `key_type` via [`key_compare`](key_compare.md)
+   (heterogeneous lookup). Only participates in overload resolution if `KeyType` is usable as a key type.
+3. Removes the element at `pos`.
+4. Removes the elements in range `[first, last)`.
+
+## Template parameters
+
+`KeyType`
+:   a type comparable to `key_type` via [`key_compare`](key_compare.md)
+
+## Parameters
+
+`key` (in)
+:   key of the element to remove
+
+`pos` (in)
+:   iterator to the element to remove
+
+`first` (in)
+:   iterator to the first element to remove
+
+`last` (in)
+:   iterator one past the last element to remove
+
+## Return value
+
+1. number of elements removed (0 or 1)
+2. number of elements removed (0 or 1)
+3. iterator following the removed element
+4. iterator following the last removed element
+
+## Complexity
+
+Linear in the number of elements (elements after the removed one(s) are shifted to keep storage
+contiguous).
+
+## Examples
+
+??? example
+
+    The example shows how `erase` is used.
+
+    ```cpp
+    --8<-- "examples/ordered_map__erase.cpp"
+    ```
+
+    Output:
+
+    ```
+    --8<-- "examples/ordered_map__erase.output"
+    ```
+
+## Version history
+
+- Added in version 3.9.0 to implement [`nlohmann::ordered_json`](../ordered_json.md).
+- Overload (2) added in version 3.11.0.
@@ -0,0 +1,56 @@
+# <small>nlohmann::ordered_map::</small>find
+
+```cpp
+// (1)
+iterator find(const key_type& key);
+const_iterator find(const key_type& key) const;
+
+// (2)
+template<class KeyType>
+iterator find(KeyType&& key);
+template<class KeyType>
+const_iterator find(KeyType&& key) const;
+```
+
+1. Returns an iterator to the element with key equal to `key`, or `end()` if no such element exists.
+2. Same as (1), but for any `KeyType` comparable to `key_type` via [`key_compare`](key_compare.md)
+   (heterogeneous lookup). Only participates in overload resolution if `KeyType` is usable as a key type.
+
+## Template parameters
+
+`KeyType`
+:   a type comparable to `key_type` via [`key_compare`](key_compare.md)
+
+## Parameters
+
+`key` (in)
+:   key of the element to find
+
+## Return value
+
+iterator to the element with key equal to `key`, or `end()` if not found
+
+## Complexity
+
+Linear in the number of elements.
+
+## Examples
+
+??? example
+
+    The example shows how `find` is used.
+
+    ```cpp
+    --8<-- "examples/ordered_map__find.cpp"
+    ```
+
+    Output:
+
+    ```
+    --8<-- "examples/ordered_map__find.output"
+    ```
+
+## Version history
+
+- Added in version 3.9.1 to implement [`nlohmann::ordered_json`](../ordered_json.md).
+- Overload (2) added in version 3.11.0.
@@ -6,7 +6,7 @@ template<class Key, class T, class IgnoredLess = std::less<Key>,
 struct ordered_map : std::vector<std::pair<const Key, T>, Allocator>;
 ```

-A minimal map-like container that preserves insertion order for use within [`nlohmann::ordered_json`](ordered_json.md)
+A minimal map-like container that preserves insertion order for use within [`nlohmann::ordered_json`](../ordered_json.md)
 (`nlohmann::basic_json<ordered_map>`).

 ## Template parameters
@@ -30,19 +30,19 @@ case all iterators (including the `end()` iterator) and all references to the el

 When the storage grows, the keys are copied and the mapped values are moved to the new storage. A plain `std::vector`
 would copy the whole elements instead, because their `#!cpp const` keys make them not nothrow move constructible; for
-[`ordered_json`](ordered_json.md), this would be a deep copy of every nested value. The values are only copied if
+[`ordered_json`](../ordered_json.md), this would be a deep copy of every nested value. The values are only copied if
 `T` is not default constructible or not nothrow move assignable.

 ## Member types

 - **key_type** - key type (`Key`)
 - **mapped_type** - mapped type (`T`)
- **Container** - base container type (`#!cpp std::vector<std::pair<const Key, T>, Allocator>`)
+- [**Container**](Container.md) - base container type (`#!cpp std::vector<std::pair<const Key, T>, Allocator>`)
 - **iterator**
 - **const_iterator**
 - **size_type**
 - **value_type**
- **key_compare** - key comparison function
+- [**key_compare**](key_compare.md) - key comparison function
 ```cpp
 std::equal_to<Key>  // until C++14

@@ -51,15 +51,16 @@ std::equal_to<>     // since C++14

 ## Member functions

- (constructor)
- (destructor)
- **emplace**
- **operator\[\]**
- **at**
- **erase**
- **count**
- **find**
- **insert**
+- [(constructor)](ordered_map.md)
+- [(destructor)](~ordered_map.md)
+- [**operator=**](operator=.md)
+- [**emplace**](emplace.md)
+- [**operator\[\]**](operator[].md)
+- [**at**](at.md)
+- [**erase**](erase.md)
+- [**count**](count.md)
+- [**find**](find.md)
+- [**insert**](insert.md)

 ## Exception safety

@@ -89,7 +90,7 @@ This differs from `#!cpp std::map`, where the same operations are O(log n).
 !!! warning "Quadratic cost of building large objects"

    Because every insertion scans all elements inserted so far, building an object of `n` distinct keys costs
-    **O(n²)** in total. This applies to filling an [`ordered_json`](ordered_json.md) object key by key as well as to
+    **O(n²)** in total. This applies to filling an [`ordered_json`](../ordered_json.md) object key by key as well as to
    parsing one, since the parser inserts each key as it is read.

    The cost is negligible for the object sizes typically found in configuration files or API payloads, but it grows
@@ -106,7 +107,7 @@ This differs from `#!cpp std::map`, where the same operations are O(log n).
    If key order matters for objects of that size, consider a container with a lookup index, such as
    [`tsl::ordered_map`](https://github.com/Tessil/ordered-map)
    ([integration](https://github.com/nlohmann/json/issues/546#issuecomment-304447518)), as the object type -- see
-    [object order](../features/object_order.md).
+    [object order](../../features/object_order.md).

 ## Examples

@@ -126,10 +127,10 @@ This differs from `#!cpp std::map`, where the same operations are O(log n).

 ## See also

- [ordered_json](ordered_json.md)
+- [ordered_json](../ordered_json.md)

 ## Version history

- Added in version 3.9.0 to implement [`nlohmann::ordered_json`](ordered_json.md).
+- Added in version 3.9.0 to implement [`nlohmann::ordered_json`](../ordered_json.md).
 - Added **key_compare** member in version 3.11.0.
 - Changed in version 3.13.0: growing the storage moves the mapped values instead of copying them.
@@ -0,0 +1,63 @@
+# <small>nlohmann::ordered_map::</small>insert
+
+```cpp
+// (1)
+std::pair<iterator, bool> insert(value_type&& value);
+std::pair<iterator, bool> insert(const value_type& value);
+
+// (2)
+template<typename InputIt>
+void insert(InputIt first, InputIt last);
+```
+
+1. Inserts `value` if no element with an equal key already exists (per [`key_compare`](key_compare.md)),
+   appending it at the end to preserve insertion order. If an equal key already exists, does nothing.
+2. Inserts the elements from range `[first, last)`, in iteration order, applying the same equal-key rule
+   as (1) to each element.
+
+## Template parameters
+
+`InputIt`
+:   an input iterator type
+
+## Parameters
+
+`value` (in)
+:   value to insert
+
+`first` (in)
+:   iterator to the first element to insert
+
+`last` (in)
+:   iterator one past the last element to insert
+
+## Return value
+
+1. pair of an iterator to the (possibly newly inserted) element, and a `bool` that is `true` if insertion
+   took place and `false` if an element with an equal key already existed
+2. (none)
+
+## Complexity
+
+1. Linear in the number of elements.
+2. Linear in the distance between `first` and `last`, times linear in the number of elements.
+
+## Examples
+
+??? example
+
+    The example shows how `insert` is used.
+
+    ```cpp
+    --8<-- "examples/ordered_map__insert.cpp"
+    ```
+
+    Output:
+
+    ```
+    --8<-- "examples/ordered_map__insert.output"
+    ```
+
+## Version history
+
+- Added in version 3.9.1 to implement [`nlohmann::ordered_json`](../ordered_json.md).
@@ -0,0 +1,34 @@
+# <small>nlohmann::ordered_map::</small>key_compare
+
+```cpp
+using key_compare = std::equal_to<Key>;  // until C++14
+
+using key_compare = std::equal_to<>;     // since C++14
+```
+
+The comparator used to determine key equality when looking up elements. Unlike `std::map`, `ordered_map`
+uses linear search with `key_compare` rather than an ordering relation, since element order reflects
+insertion order rather than key order.
+
+Since C++14, the transparent `#!cpp std::equal_to<>` is used, which enables heterogeneous lookup (e.g.
+looking up by a `#!cpp const char*` key without constructing a temporary `Key`).
+
+## Examples
+
+??? example
+
+    The example shows how `key_compare` is used.
+
+    ```cpp
+    --8<-- "examples/ordered_map__key_compare.cpp"
+    ```
+
+    Output:
+
+    ```
+    --8<-- "examples/ordered_map__key_compare.output"
+    ```
+
+## Version history
+
+- Added in version 3.11.0.
@@ -0,0 +1,32 @@
+# <small>nlohmann::ordered_map::</small>operator=
+
+```cpp
+// (1)
+ordered_map& operator=(const ordered_map& other);
+
+// (2)
+ordered_map& operator=(ordered_map&& other) noexcept(std::is_nothrow_move_assignable<Container>::value);
+```
+
+1. Copy assignment operator.
+2. Move assignment operator.
+
+## Parameters
+
+`other` (in)
+:   value to assign from
+
+## Return value
+
+`*this`
+
+## Complexity
+
+1. Linear in the size of `other`.
+2. Constant.
+
+<!-- NOLINT Examples -->
+
+## Version history
+
+- Added in version 3.9.0 to implement [`nlohmann::ordered_json`](../ordered_json.md).
@@ -0,0 +1,62 @@
+# <small>nlohmann::ordered_map::</small>operator[]
+
+```cpp
+// (1)
+T& operator[](const key_type& key);
+const T& operator[](const key_type& key) const;
+
+// (2)
+template<class KeyType>
+T& operator[](KeyType&& key);
+template<class KeyType>
+const T& operator[](KeyType&& key) const;
+```
+
+1. Returns a reference to the value mapped to `key`, inserting a default-constructed `T` (non-`const`
+   overload only) if no such element exists yet.
+2. Same as (1), but for any `KeyType` comparable to `key_type` via [`key_compare`](key_compare.md)
+   (heterogeneous lookup). Only participates in overload resolution if `KeyType` is usable as a key type.
+
+## Template parameters
+
+`KeyType`
+:   a type comparable to `key_type` via [`key_compare`](key_compare.md)
+
+## Parameters
+
+`key` (in)
+:   key of the element to find or insert
+
+## Return value
+
+reference to the mapped value of the element with key equal to `key`
+
+## Exceptions
+
+The `const` overloads throw `std::out_of_range` if no element with key `key` exists (they delegate to
+[`at`](at.md)).
+
+## Complexity
+
+Linear in the number of elements.
+
+## Examples
+
+??? example
+
+    The example shows how `operator[]` is used.
+
+    ```cpp
+    --8<-- "examples/ordered_map__operator_idx.cpp"
+    ```
+
+    Output:
+
+    ```
+    --8<-- "examples/ordered_map__operator_idx.output"
+    ```
+
+## Version history
+
+- Added in version 3.9.0 to implement [`nlohmann::ordered_json`](../ordered_json.md).
+- Overload (2) added in version 3.11.0.
@@ -0,0 +1,66 @@
+# <small>nlohmann::ordered_map::</small>ordered_map
+
+```cpp
+// (1)
+ordered_map() noexcept(noexcept(Container()));
+
+// (2)
+explicit ordered_map(const Allocator& alloc) noexcept(noexcept(Container(alloc)));
+
+// (3)
+template <class It>
+ordered_map(It first, It last, const Allocator& alloc = Allocator());
+
+// (4)
+ordered_map(std::initializer_list<value_type> init, const Allocator& alloc = Allocator());
+
+// (5)
+ordered_map(const ordered_map&) = default;
+
+// (6)
+ordered_map(ordered_map&&) noexcept(std::is_nothrow_move_constructible<Container>::value) = default;
+```
+
+1. Default constructor. Creates an empty `ordered_map`.
+2. Creates an empty `ordered_map` using the given allocator.
+3. Creates an `ordered_map` from the elements in range `[first, last)`, inserted in iteration order.
+4. Creates an `ordered_map` from an initializer list of key/value pairs, inserted in list order.
+5. Copy constructor.
+6. Move constructor.
+
+These constructors are declared explicitly (rather than inherited via `#!cpp using Container::Container`)
+because older compilers (GCC <= 5.5, Xcode <= 9.4) do not handle the inherited constructors correctly.
+
+## Template parameters
+
+`It`
+:   an input iterator type
+
+## Parameters
+
+`alloc` (in)
+:   allocator to use for the underlying container
+
+`first` (in)
+:   iterator to the first element to insert
+
+`last` (in)
+:   iterator one past the last element to insert
+
+`init` (in)
+:   initializer list of key/value pairs to insert
+
+## Complexity
+
+1. Constant.
+2. Constant.
+3. Linear in the distance between `first` and `last`.
+4. Linear in the size of `init`.
+5. Linear in the size of `other`.
+6. Constant.
+
+<!-- NOLINT Examples -->
+
+## Version history
+
+- Added in version 3.9.0 to implement [`nlohmann::ordered_json`](../ordered_json.md).
@@ -0,0 +1,17 @@
+# <small>nlohmann::ordered_map::</small>~ordered_map
+
+```cpp
+~ordered_map() = default;
+```
+
+Destroys the `ordered_map` and frees all allocated memory.
+
+## Complexity
+
+Linear in the number of elements.
+
+<!-- NOLINT Examples -->
+
+## Version history
+
+- Added in version 3.9.0 to implement [`nlohmann::ordered_json`](../ordered_json.md).
@@ -0,0 +1,21 @@
+#include <iostream>
+#include <nlohmann/json.hpp>
+
+using json = nlohmann::json;
+
+int main()
+{
+    // an empty binary value is encoded differently by the two drafts:
+    // draft2 omits the optimized type marker for an empty byte array,
+    // while draft3 always writes it
+    json j = json::binary({});
+
+    // encode using BJData draft2 (the default)
+    auto v_draft2 = json::to_bjdata(j, true, true, json::bjdata_version_t::draft2);
+
+    // encode using BJData draft3
+    auto v_draft3 = json::to_bjdata(j, true, true, json::bjdata_version_t::draft3);
+
+    std::cout << "draft2 size: " << v_draft2.size() << '\n'
+              << "draft3 size: " << v_draft3.size() << std::endl;
+}
@@ -0,0 +1,2 @@
+draft2 size: 4
+draft3 size: 6
@@ -0,0 +1,11 @@
+#include <iostream>
+#include <nlohmann/json.hpp>
+
+using byte_container_with_subtype = nlohmann::byte_container_with_subtype<std::vector<std::uint8_t>>;
+
+int main()
+{
+    std::cout << std::boolalpha
+              << std::is_same<byte_container_with_subtype::container_type, std::vector<std::uint8_t>>::value
+              << std::endl;
+}
@@ -0,0 +1 @@
+true
@@ -0,0 +1,15 @@
+#include <iostream>
+#include <nlohmann/json.hpp>
+
+using byte_container_with_subtype = nlohmann::byte_container_with_subtype<std::vector<std::uint8_t>>;
+
+int main()
+{
+    byte_container_with_subtype c1({0xca, 0xfe});
+    byte_container_with_subtype c2({0xca, 0xfe});
+    byte_container_with_subtype c3({0xca, 0xfe}, 42);
+
+    std::cout << std::boolalpha
+              << "c1 == c2: " << (c1 == c2) << '\n'
+              << "c1 == c3: " << (c1 == c3) << std::endl;
+}
@@ -0,0 +1,2 @@
+c1 == c2: true
+c1 == c3: false
@@ -0,0 +1,15 @@
+#include <iostream>
+#include <nlohmann/json.hpp>
+
+using byte_container_with_subtype = nlohmann::byte_container_with_subtype<std::vector<std::uint8_t>>;
+
+int main()
+{
+    byte_container_with_subtype c1({0xca, 0xfe});
+    byte_container_with_subtype c2({0xca, 0xfe});
+    byte_container_with_subtype c3({0xca, 0xfe}, 42);
+
+    std::cout << std::boolalpha
+              << "c1 != c2: " << (c1 != c2) << '\n'
+              << "c1 != c3: " << (c1 != c3) << std::endl;
+}
@@ -0,0 +1,2 @@
+c1 != c2: false
+c1 != c3: true
@@ -0,0 +1,10 @@
+#include <iostream>
+#include <nlohmann/json.hpp>
+
+using byte_container_with_subtype = nlohmann::byte_container_with_subtype<std::vector<std::uint8_t>>;
+
+int main()
+{
+    std::cout << std::boolalpha
+              << std::is_same<byte_container_with_subtype::subtype_type, std::uint64_t>::value << std::endl;
+}
@@ -0,0 +1 @@
+true
@@ -0,0 +1,13 @@
+#include <iostream>
+#include <nlohmann/json.hpp>
+
+using json = nlohmann::json;
+
+int main()
+{
+    // an initializer_list_t is what a braced-init-list of JSON values is deduced as
+    json::initializer_list_t init = {"a", 1, 2.0, false};
+
+    json j(init);
+    std::cout << j.dump() << std::endl;
+}
@@ -0,0 +1 @@
+["a",1,2.0,false]
@@ -0,0 +1,10 @@
+#include <iostream>
+#include <nlohmann/json.hpp>
+
+using json = nlohmann::json;
+
+int main()
+{
+    std::cout << std::boolalpha
+              << std::is_same<json::json_sax_t::binary_t, json::binary_t>::value << std::endl;
+}
@@ -0,0 +1 @@
+true
@@ -0,0 +1,10 @@
+#include <iostream>
+#include <nlohmann/json.hpp>
+
+using json = nlohmann::json;
+
+int main()
+{
+    std::cout << std::boolalpha
+              << std::is_same<json::json_sax_t::number_float_t, json::number_float_t>::value << std::endl;
+}
@@ -0,0 +1 @@
+true
@@ -0,0 +1,10 @@
+#include <iostream>
+#include <nlohmann/json.hpp>
+
+using json = nlohmann::json;
+
+int main()
+{
+    std::cout << std::boolalpha
+              << std::is_same<json::json_sax_t::number_integer_t, json::number_integer_t>::value << std::endl;
+}
@@ -0,0 +1 @@
+true
@@ -0,0 +1,10 @@
+#include <iostream>
+#include <nlohmann/json.hpp>
+
+using json = nlohmann::json;
+
+int main()
+{
+    std::cout << std::boolalpha
+              << std::is_same<json::json_sax_t::number_unsigned_t, json::number_unsigned_t>::value << std::endl;
+}
@@ -0,0 +1 @@
+true
@@ -0,0 +1,10 @@
+#include <iostream>
+#include <nlohmann/json.hpp>
+
+using json = nlohmann::json;
+
+int main()
+{
+    std::cout << std::boolalpha
+              << std::is_same<json::json_sax_t::string_t, json::string_t>::value << std::endl;
+}
@@ -0,0 +1 @@
+true
@@ -0,0 +1,10 @@
+#include <iostream>
+#include <nlohmann/json.hpp>
+
+using json = nlohmann::json;
+
+int main()
+{
+    std::cout << std::boolalpha
+              << std::is_same<json::json_sax_t, nlohmann::json_sax<json>>::value << std::endl;
+}
@@ -0,0 +1 @@
+true
@@ -0,0 +1,12 @@
+#include <iostream>
+#include <nlohmann/json.hpp>
+
+int main()
+{
+    using Map = nlohmann::ordered_map<std::string, int>;
+
+    std::cout << std::boolalpha
+              << "Container is std::vector<std::pair<const Key, T>>: "
+              << std::is_same<Map::Container, std::vector<std::pair<const std::string, int>>>::value
+              << std::endl;
+}
@@ -0,0 +1 @@
+Container is std::vector<std::pair<const Key, T>>: true
@@ -0,0 +1,26 @@
+#include <iostream>
+#include <nlohmann/json.hpp>
+
+int main()
+{
+    nlohmann::ordered_map<std::string, int> m;
+    m["one"] = 1;
+    m["two"] = 2;
+
+    // access an existing element
+    std::cout << "m.at(\"one\") = " << m.at("one") << std::endl;
+
+    // modify through the reference returned by at()
+    m.at("two") = 22;
+    std::cout << "m.at(\"two\") = " << m.at("two") << std::endl;
+
+    // accessing a missing key throws
+    try
+    {
+        m.at("three");
+    }
+    catch (const std::out_of_range& e)
+    {
+        std::cout << "exception: " << e.what() << std::endl;
+    }
+}
@@ -0,0 +1,3 @@
+m.at("one") = 1
+m.at("two") = 22
+exception: key not found
@@ -0,0 +1,12 @@
+#include <iostream>
+#include <nlohmann/json.hpp>
+
+int main()
+{
+    nlohmann::ordered_map<std::string, int> m;
+    m["one"] = 1;
+
+    std::cout << std::boolalpha
+              << "m.count(\"one\") = " << m.count("one") << '\n'
+              << "m.count(\"two\") = " << m.count("two") << std::endl;
+}
@@ -0,0 +1,2 @@
+m.count("one") = 1
+m.count("two") = 0
@@ -0,0 +1,15 @@
+#include <iostream>
+#include <nlohmann/json.hpp>
+
+int main()
+{
+    nlohmann::ordered_map<std::string, std::string> m;
+
+    // emplace a new element
+    auto res1 = m.emplace("one", "eins");
+    std::cout << std::boolalpha << "inserted: " << res1.second << ", value: " << res1.first->second << std::endl;
+
+    // emplace with an already-existing key: no-op, returns the existing element
+    auto res2 = m.emplace("one", "uno");
+    std::cout << std::boolalpha << "inserted: " << res2.second << ", value: " << res2.first->second << std::endl;
+}
@@ -0,0 +1,2 @@
+inserted: true, value: eins
+inserted: false, value: eins
@@ -0,0 +1,24 @@
+#include <iostream>
+#include <nlohmann/json.hpp>
+
+int main()
+{
+    nlohmann::ordered_map<std::string, int> m;
+    m["one"] = 1;
+    m["two"] = 2;
+    m["three"] = 3;
+
+    // erase by key
+    std::size_t removed = m.erase("two");
+    std::cout << "removed by key: " << removed << std::endl;
+
+    // erase by iterator
+    m.erase(m.begin());
+
+    std::cout << "remaining: ";
+    for (const auto& element : m)
+    {
+        std::cout << element.first << ' ';
+    }
+    std::cout << std::endl;
+}
@@ -0,0 +1,2 @@
+removed by key: 1
+remaining: three 
@@ -0,0 +1,19 @@
+#include <iostream>
+#include <nlohmann/json.hpp>
+
+int main()
+{
+    nlohmann::ordered_map<std::string, int> m;
+    m["one"] = 1;
+
+    auto it = m.find("one");
+    if (it != m.end())
+    {
+        std::cout << "found: " << it->first << " = " << it->second << std::endl;
+    }
+
+    if (m.find("two") == m.end())
+    {
+        std::cout << "\"two\" not found" << std::endl;
+    }
+}
@@ -0,0 +1,2 @@
+found: one = 1
+"two" not found
@@ -0,0 +1,21 @@
+#include <iostream>
+#include <nlohmann/json.hpp>
+
+int main()
+{
+    nlohmann::ordered_map<std::string, int> m;
+
+    // insert a single value
+    auto res = m.insert({"one", 1});
+    std::cout << std::boolalpha << "inserted: " << res.second << std::endl;
+
+    // insert a range from another container
+    std::vector<std::pair<const std::string, int>> more = {{"two", 2}, {"three", 3}};
+    m.insert(more.begin(), more.end());
+
+    for (const auto& element : m)
+    {
+        std::cout << element.first << ':' << element.second << ' ';
+    }
+    std::cout << std::endl;
+}
@@ -0,0 +1,2 @@
+inserted: true
+one:1 two:2 three:3 
@@ -0,0 +1,12 @@
+#include <iostream>
+#include <nlohmann/json.hpp>
+
+int main()
+{
+    using Map = nlohmann::ordered_map<std::string, int>;
+    Map::key_compare compare{};
+
+    std::cout << std::boolalpha
+              << "compare(\"a\", \"a\") = " << compare("a", "a") << '\n'
+              << "compare(\"a\", \"b\") = " << compare("a", "b") << std::endl;
+}
@@ -0,0 +1,2 @@
+compare("a", "a") = true
+compare("a", "b") = false
@@ -0,0 +1,14 @@
+#include <iostream>
+#include <nlohmann/json.hpp>
+
+int main()
+{
+    nlohmann::ordered_map<std::string, int> m;
+
+    // operator[] inserts a default-constructed value if the key doesn't exist yet
+    m["one"] = 1;
+    std::cout << "m[\"one\"] = " << m["one"] << std::endl;
+
+    // accessing again just returns the existing value
+    std::cout << "m[\"one\"] = " << m["one"] << std::endl;
+}
@@ -0,0 +1,2 @@
+m["one"] = 1
+m["one"] = 1
@@ -51,16 +51,16 @@ If you do want to preserve the **insertion order**, you can use the type [`nlohm
    --8<-- "examples/ordered_json.output"
    ```

-Alternatively, [`nlohmann::fifo_map`](https://github.com/nlohmann/fifo_map) also preserves the insertion order and, unlike [`ordered_map`](../api/ordered_map.md), keeps a lookup index, so it does not have the quadratic cost described below. It is used through a small adapter ([integration](https://github.com/nlohmann/json/issues/485#issuecomment-333652309)).
+Alternatively, [`nlohmann::fifo_map`](https://github.com/nlohmann/fifo_map) also preserves the insertion order and, unlike [`ordered_map`](../api/ordered_map/index.md), keeps a lookup index, so it does not have the quadratic cost described below. It is used through a small adapter ([integration](https://github.com/nlohmann/json/issues/485#issuecomment-333652309)).

 If the order does not matter and you only want faster lookup, `boost::unordered_flat_map`, `absl::flat_hash_map`, `absl::node_hash_map`, and several other hash maps work through an adapter that restores the template argument order `basic_json` expects; see [Template Parameter Requirements](types/template_parameters.md#objecttype). Note these are *unordered*, not insertion-ordered.

 [`tsl::ordered_map`](https://github.com/Tessil/ordered-map) cannot be used: its iterators expose the mapped value as `const`, while `basic_json` needs to modify it in place.

-The [`ordered_map`](../api/ordered_map.md) behind `nlohmann::ordered_json` is deliberately minimal and has no lookup
+The [`ordered_map`](../api/ordered_map/index.md) behind `nlohmann::ordered_json` is deliberately minimal and has no lookup
 index, so every key access is a linear scan and building an object of `n` keys costs O(n²). This is unnoticeable at
 typical object sizes but becomes significant for objects with many thousands of keys; see
-[`ordered_map` complexity](../api/ordered_map.md#complexity). The alternatives above keep a lookup index and do not
+[`ordered_map` complexity](../api/ordered_map/index.md#complexity). The alternatives above keep a lookup index and do not
 have this cost.

 ### Notes on parsing
@@ -71,11 +71,10 @@ otherwise, it uses unsigned integer storage.

    - 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 with
-      [`std::strtold`](https://en.cppreference.com/w/cpp/string/byte/strtof), which gets the decimal point of the
-      current locale, also one longer than one byte (e.g., in `fa_IR.UTF-8`).
+    - As of version 3.9.1, the conversion is 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`](https://en.cppreference.com/w/cpp/string/byte/strtof), respectively.

 !!! example "Examples"

@@ -86,10 +85,10 @@ otherwise, it uses unsigned integer storage.
 ### 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;`.
@@ -26,9 +26,8 @@ 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 silently misparses numbers,
+      because the lexer hands the buffer to `#!cpp std::strtoull`/`#!cpp std::strtoll`/`#!cpp std::strtod`.
    - 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
@@ -38,7 +37,7 @@ Requirements are split into two groups:

 | Template parameter                                                | Default                           | Notable substitutes                                                   |
 |-------------------------------------------------------------------|-----------------------------------|-----------------------------------------------------------------------|
-| [`ObjectType`](#objecttype)                                       | `std::map`                        | [`nlohmann::ordered_map`](../../api/ordered_map.md), Abseil hash maps |
+| [`ObjectType`](#objecttype)                                       | `std::map`                        | [`nlohmann::ordered_map`](../../api/ordered_map/index.md), Abseil hash maps |
 | [`ArrayType`](#arraytype)                                         | `std::vector`                     | `#!cpp std::deque`                                                    |
 | [`StringType`](#stringtype)                                       | `std::string`                     | `std::string`-like types over `char`                                  |
 | [`BooleanType`](#booleantype)                                     | `bool`                            | none worth using                                                      |
@@ -231,7 +230,7 @@ The library does not sort or de-duplicate keys itself; the behavior described in
 | Container                                                                        | Notes                                                                         |
 |----------------------------------------------------------------------------------|-------------------------------------------------------------------------------|
 | `#!cpp std::map` (default)                                                       |                                                                               |
-| [`nlohmann::ordered_map`](../../api/ordered_map.md)                              | used by [`ordered_json`](../../api/ordered_json.md); keeps insertion order    |
+| [`nlohmann::ordered_map`](../../api/ordered_map/index.md)                              | used by [`ordered_json`](../../api/ordered_json.md); keeps insertion order    |
 | [`nlohmann::fifo_map`](https://github.com/nlohmann/fifo_map)                     | keeps insertion order; adapter puts `fifo_map_compare` in the comparator slot |
 | `boost::container::map`, `boost::container::flat_map`                            | no adapter needed                                                             |
 | `#!cpp std::unordered_map`                                                       | through the adapter above; not with libstdc++ 9, see the note                 |
@@ -536,10 +535,8 @@ 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::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`).
@@ -50,7 +50,7 @@ The public headers are in [`include/nlohmann`](https://github.com/nlohmann/json/
 - [`adl_serializer.hpp`](https://github.com/nlohmann/json/blob/develop/include/nlohmann/adl_serializer.hpp), [`byte_container_with_subtype.hpp`](https://github.com/nlohmann/json/blob/develop/include/nlohmann/byte_container_with_subtype.hpp), and [`ordered_map.hpp`](https://github.com/nlohmann/json/blob/develop/include/nlohmann/ordered_map.hpp) define
  [`adl_serializer`](../api/adl_serializer/index.md),
  [`byte_container_with_subtype`](../api/byte_container_with_subtype/index.md), and
-  [`ordered_map`](../api/ordered_map.md).
+  [`ordered_map`](../api/ordered_map/index.md).

 Everything else lives in [`detail/`](https://github.com/nlohmann/json/tree/develop/include/nlohmann/detail) and namespace `nlohmann::detail`, which is not part of the public API. Paths
 below are relative to `include/nlohmann`.
@@ -97,7 +97,7 @@ is generated from these files with `make amalgamate` and must not be edited by h
 The library provides two specializations:

 - [`json`](../api/json.md) uses all default template arguments.
- [`ordered_json`](../api/ordered_json.md) uses [`ordered_map`](../api/ordered_map.md) as `ObjectType` to keep the
+- [`ordered_json`](../api/ordered_json.md) uses [`ordered_map`](../api/ordered_map/index.md) as `ObjectType` to keep the
  insertion order of object keys.

 The requirements on the template arguments are listed in
@@ -20,4 +20,4 @@ The class contains a slightly modified version of the Grisu2 algorithm from Flor

 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
@@ -2,7 +2,8 @@

 This page summarizes the notable changes of every release and links to the relevant documentation.
 The **complete release notes** — including all changes, the download files, and their checksums — are
-published on the [GitHub releases page](https://github.com/nlohmann/json/releases).
+published on the [GitHub releases page](https://github.com/nlohmann/json/releases). For a raw,
+signature-level diff of the public API between releases, see [API Changes](api_changes.md).

 ## v3.12.0 (2025-04-11)

@@ -52,6 +52,7 @@ nav:
      - "FAQ": home/faq.md
      - home/exceptions.md
      - home/releases.md
+      - home/api_changes.md
      - home/design_goals.md
      - home/architecture.md
      - home/customers.md
@@ -119,6 +120,7 @@ nav:
          - 'begin': api/basic_json/begin.md
          - 'binary': api/basic_json/binary.md
          - 'binary_t': api/basic_json/binary_t.md
+          - 'bjdata_version_t': api/basic_json/bjdata_version_t.md
          - 'boolean_t': api/basic_json/boolean_t.md
          - 'cbegin': api/basic_json/cbegin.md
          - 'cbor_tag_handler_t': api/basic_json/cbor_tag_handler_t.md
@@ -157,6 +159,7 @@ nav:
          - 'get_to': api/basic_json/get_to.md
          - 'std::formatter&lt;basic_json&gt;': api/basic_json/std_formatter.md
          - 'std::hash&lt;basic_json&gt;': api/basic_json/std_hash.md
+          - 'initializer_list_t': api/basic_json/initializer_list_t.md
          - 'input_format_t': api/basic_json/input_format_t.md
          - 'insert': api/basic_json/insert.md
          - 'invalid_iterator': api/basic_json/invalid_iterator.md
@@ -175,6 +178,7 @@ nav:
          - 'is_structured': api/basic_json/is_structured.md
          - 'items': api/basic_json/items.md
          - 'json_base_class_t': api/basic_json/json_base_class_t.md
+          - 'json_sax_t': api/basic_json/json_sax_t.md
          - 'json_serializer': api/basic_json/json_serializer.md
          - 'max_size': api/basic_json/max_size.md
          - 'meta': api/basic_json/meta.md
@@ -232,9 +236,13 @@ nav:
          - 'Overview': api/byte_container_with_subtype/index.md
          - '(constructor)': api/byte_container_with_subtype/byte_container_with_subtype.md
          - 'clear_subtype': api/byte_container_with_subtype/clear_subtype.md
+          - 'container_type': api/byte_container_with_subtype/container_type.md
          - 'has_subtype': api/byte_container_with_subtype/has_subtype.md
+          - 'operator==': api/byte_container_with_subtype/operator_eq.md
+          - 'operator!=': api/byte_container_with_subtype/operator_ne.md
          - 'set_subtype': api/byte_container_with_subtype/set_subtype.md
          - 'subtype': api/byte_container_with_subtype/subtype.md
+          - 'subtype_type': api/byte_container_with_subtype/subtype_type.md
      - adl_serializer:
          - 'Overview': api/adl_serializer/index.md
          - 'from_json': api/adl_serializer/from_json.md
@@ -260,25 +268,46 @@ nav:
          - 'to_string': api/json_pointer/to_string.md
      - json_sax:
          - 'Overview': api/json_sax/index.md
+          - '(Constructor)': api/json_sax/json_sax.md
+          - '(Destructor)': api/json_sax/~json_sax.md
+          - 'operator=': api/json_sax/operator=.md
          - 'binary': api/json_sax/binary.md
+          - 'binary_t': api/json_sax/binary_t.md
          - 'boolean': api/json_sax/boolean.md
          - 'end_array': api/json_sax/end_array.md
          - 'end_object': api/json_sax/end_object.md
          - 'key': api/json_sax/key.md
          - 'null': api/json_sax/null.md
          - 'number_float': api/json_sax/number_float.md
+          - 'number_float_t': api/json_sax/number_float_t.md
          - 'number_integer': api/json_sax/number_integer.md
+          - 'number_integer_t': api/json_sax/number_integer_t.md
          - 'number_unsigned': api/json_sax/number_unsigned.md
+          - 'number_unsigned_t': api/json_sax/number_unsigned_t.md
          - 'parse_error': api/json_sax/parse_error.md
          - 'start_array': api/json_sax/start_array.md
          - 'start_object': api/json_sax/start_object.md
          - 'string': api/json_sax/string.md
+          - 'string_t': api/json_sax/string_t.md
      - 'operator<<(basic_json), operator<<(json_pointer)': api/operator_ltlt.md
      - 'operator>>(basic_json)': api/operator_gtgt.md
      - 'operator""_json': api/operator_literal_json.md
      - 'operator""_json_pointer': api/operator_literal_json_pointer.md
      - 'ordered_json': api/ordered_json.md
-      - 'ordered_map': api/ordered_map.md
+      - ordered_map:
+          - 'Overview': api/ordered_map/index.md
+          - '(Constructor)': api/ordered_map/ordered_map.md
+          - '(Destructor)': api/ordered_map/~ordered_map.md
+          - 'operator=': api/ordered_map/operator=.md
+          - 'at': api/ordered_map/at.md
+          - 'Container': api/ordered_map/Container.md
+          - 'count': api/ordered_map/count.md
+          - 'emplace': api/ordered_map/emplace.md
+          - 'erase': api/ordered_map/erase.md
+          - 'find': api/ordered_map/find.md
+          - 'insert': api/ordered_map/insert.md
+          - 'key_compare': api/ordered_map/key_compare.md
+          - 'operator[]': api/ordered_map/operator[].md
      - macros:
          - 'Overview': api/macros/index.md
          - 'JSON_ASSERT': api/macros/json_assert.md
@@ -22,7 +22,9 @@ template<typename BinaryType>
 class byte_container_with_subtype : public BinaryType
 {
  public:
+    /// @sa https://json.nlohmann.me/api/byte_container_with_subtype/container_type/
    using container_type = BinaryType;
+    /// @sa https://json.nlohmann.me/api/byte_container_with_subtype/subtype_type/
    using subtype_type = std::uint64_t;

    /// @sa https://json.nlohmann.me/api/byte_container_with_subtype/byte_container_with_subtype/
@@ -54,12 +56,14 @@ class byte_container_with_subtype : public BinaryType
        , m_has_subtype(true)
    {}

+    /// @sa https://json.nlohmann.me/api/byte_container_with_subtype/operator_eq/
    bool operator==(const byte_container_with_subtype& rhs) const
    {
        return std::tie(static_cast<const BinaryType&>(*this), m_subtype, m_has_subtype) ==
               std::tie(static_cast<const BinaryType&>(rhs), rhs.m_subtype, rhs.m_has_subtype);
    }

+    /// @sa https://json.nlohmann.me/api/byte_container_with_subtype/operator_ne/
    bool operator!=(const byte_container_with_subtype& rhs) const
    {
        return !(rhs == *this);
@@ -39,25 +39,6 @@ inline int count_leading_zeros(std::uint64_t x) noexcept
 #endif
 }

-/// number of trailing zero bits of x (x != 0)
-inline int count_trailing_zeros(std::uint64_t x) noexcept
-{
-#if defined(__GNUC__) || defined(__clang__)
-    return __builtin_ctzll(x);
-#else
-    int n = 0;
-    for (int shift = 32; shift != 0; shift >>= 1)
-    {
-        if ((x << (64 - shift)) == 0)
-        {
-            n += shift;
-            x >>= shift;
-        }
-    }
-    return n;
-#endif
-}
-
 /// the 128-bit product of two 64-bit numbers
 struct uint128_parts
 {
@@ -87,19 +68,14 @@ inline uint128_parts full_multiplication(std::uint64_t a, std::uint64_t b) noexc

 /// 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 unsigned char* b) noexcept
+inline std::uint64_t read_eight_bytes(const char* p) noexcept
 {
+    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);
 }

-/// eight bytes as a little-endian word
-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
 NLOHMANN_JSON_NAMESPACE_END
@@ -33,15 +33,21 @@ input.
 template<typename BasicJsonType>
 struct json_sax
 {
+    /// @sa https://json.nlohmann.me/api/json_sax/number_integer_t/
    using number_integer_t = typename BasicJsonType::number_integer_t;
+    /// @sa https://json.nlohmann.me/api/json_sax/number_unsigned_t/
    using number_unsigned_t = typename BasicJsonType::number_unsigned_t;
+    /// @sa https://json.nlohmann.me/api/json_sax/number_float_t/
    using number_float_t = typename BasicJsonType::number_float_t;
+    /// @sa https://json.nlohmann.me/api/json_sax/string_t/
    using string_t = typename BasicJsonType::string_t;
+    /// @sa https://json.nlohmann.me/api/json_sax/binary_t/
    using binary_t = typename BasicJsonType::binary_t;

    /*!
    @brief a null value was read
    @return whether parsing should proceed
+    @sa https://json.nlohmann.me/api/json_sax/null/
    */
    virtual bool null() = 0;

@@ -49,6 +55,7 @@ struct json_sax
    @brief a boolean value was read
    @param[in] val  boolean value
    @return whether parsing should proceed
+    @sa https://json.nlohmann.me/api/json_sax/boolean/
    */
    virtual bool boolean(bool val) = 0;

@@ -56,6 +63,7 @@ struct json_sax
    @brief an integer number was read
    @param[in] val  integer value
    @return whether parsing should proceed
+    @sa https://json.nlohmann.me/api/json_sax/number_integer/
    */
    virtual bool number_integer(number_integer_t val) = 0;

@@ -63,6 +71,7 @@ struct json_sax
    @brief an unsigned integer number was read
    @param[in] val  unsigned integer value
    @return whether parsing should proceed
+    @sa https://json.nlohmann.me/api/json_sax/number_unsigned/
    */
    virtual bool number_unsigned(number_unsigned_t val) = 0;

@@ -71,6 +80,7 @@ struct json_sax
    @param[in] val  floating-point value
    @param[in] s    raw token value
    @return whether parsing should proceed
+    @sa https://json.nlohmann.me/api/json_sax/number_float/
    */
    virtual bool number_float(number_float_t val, const string_t& s) = 0;

@@ -79,6 +89,7 @@ struct json_sax
    @param[in] val  string value
    @return whether parsing should proceed
    @note It is safe to move the passed string value.
+    @sa https://json.nlohmann.me/api/json_sax/string/
    */
    virtual bool string(string_t& val) = 0;

@@ -87,6 +98,7 @@ struct json_sax
    @param[in] val  binary value
    @return whether parsing should proceed
    @note It is safe to move the passed binary value.
+    @sa https://json.nlohmann.me/api/json_sax/binary/
    */
    virtual bool binary(binary_t& val) = 0;

@@ -95,6 +107,7 @@ struct json_sax
    @param[in] elements  number of object elements or -1 if unknown
    @return whether parsing should proceed
    @note binary formats may report the number of elements
+    @sa https://json.nlohmann.me/api/json_sax/start_object/
    */
    virtual bool start_object(std::size_t elements) = 0;

@@ -103,12 +116,14 @@ struct json_sax
    @param[in] val  object key
    @return whether parsing should proceed
    @note It is safe to move the passed string.
+    @sa https://json.nlohmann.me/api/json_sax/key/
    */
    virtual bool key(string_t& val) = 0;

    /*!
    @brief the end of an object was read
    @return whether parsing should proceed
+    @sa https://json.nlohmann.me/api/json_sax/end_object/
    */
    virtual bool end_object() = 0;

@@ -117,12 +132,14 @@ struct json_sax
    @param[in] elements  number of array elements or -1 if unknown
    @return whether parsing should proceed
    @note binary formats may report the number of elements
+    @sa https://json.nlohmann.me/api/json_sax/start_array/
    */
    virtual bool start_array(std::size_t elements) = 0;

    /*!
    @brief the end of an array was read
    @return whether parsing should proceed
+    @sa https://json.nlohmann.me/api/json_sax/end_array/
    */
    virtual bool end_array() = 0;

@@ -132,16 +149,23 @@ struct json_sax
    @param[in] last_token  the last read token
    @param[in] ex          an exception object describing the error
    @return whether parsing should proceed (must return false)
+    @sa https://json.nlohmann.me/api/json_sax/parse_error/
    */
    virtual bool parse_error(std::size_t position,
                             const std::string& last_token,
                             const detail::exception& ex) = 0;

+    /// @sa https://json.nlohmann.me/api/json_sax/json_sax/
    json_sax() = default;
+    /// @sa https://json.nlohmann.me/api/json_sax/json_sax/
    json_sax(const json_sax&) = default;
+    /// @sa https://json.nlohmann.me/api/json_sax/json_sax/
    json_sax(json_sax&&) noexcept = default;
+    /// @sa https://json.nlohmann.me/api/json_sax/operator=/
    json_sax& operator=(const json_sax&) = default;
+    /// @sa https://json.nlohmann.me/api/json_sax/operator=/
    json_sax& operator=(json_sax&&) noexcept = default;
+    /// @sa https://json.nlohmann.me/api/json_sax/~json_sax/
    virtual ~json_sax() = default;
 };

@@ -1059,11 +1059,9 @@ 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.
    {
@@ -1076,7 +1074,7 @@ 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;

@@ -1406,8 +1404,8 @@ 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)
    {
@@ -1476,11 +1474,10 @@ 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;
@@ -12,7 +12,6 @@
 #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
@@ -70,12 +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)
@@ -109,7 +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)
@@ -120,9 +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)
@@ -249,18 +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;
 }
@@ -275,7 +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)
@@ -283,8 +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)
@@ -57,6 +57,7 @@ class json_pointer

  public:
    // for backwards compatibility accept BasicJsonType
+    /// @sa https://json.nlohmann.me/api/json_pointer/string_t/
    using string_t = typename string_t_helper<RefStringType>::type;

    /// @brief create JSON pointer
@@ -204,22 +204,31 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
    using serializer = ::nlohmann::detail::serializer<basic_json>;

  public:
+    /// @brief the type of the JSON value
+    /// @sa https://json.nlohmann.me/api/basic_json/value_t/
    using value_t = detail::value_t;
    /// JSON Pointer, see @ref nlohmann::json_pointer
    using json_pointer = ::nlohmann::json_pointer<StringType>;
    template<typename T, typename SFINAE>
    using json_serializer = JSONSerializer<T, SFINAE>;
    /// how to treat decoding errors
+    /// @sa https://json.nlohmann.me/api/basic_json/error_handler_t/
    using error_handler_t = detail::error_handler_t;
    /// how to treat CBOR tags
+    /// @sa https://json.nlohmann.me/api/basic_json/cbor_tag_handler_t/
    using cbor_tag_handler_t = detail::cbor_tag_handler_t;
    /// how to encode BJData
+    /// @sa https://json.nlohmann.me/api/basic_json/bjdata_version_t/
    using bjdata_version_t = detail::bjdata_version_t;
    /// helper type for initializer lists of basic_json values
+    /// @sa https://json.nlohmann.me/api/basic_json/initializer_list_t/
    using initializer_list_t = std::initializer_list<detail::json_ref<basic_json>>;

+    /// @brief the type of the SAX interface used to parse and serialize the JSON value
+    /// @sa https://json.nlohmann.me/api/basic_json/input_format_t/
    using input_format_t = detail::input_format_t;
    /// SAX interface type, see @ref nlohmann::json_sax
+    /// @sa https://json.nlohmann.me/api/basic_json/json_sax_t/
    using json_sax_t = json_sax<basic_json>;

    ////////////////
@@ -361,15 +370,19 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
    /// the template arguments passed to class @ref basic_json.
    /// @{

+#if defined(JSON_HAS_CPP_14)
    /// @brief default object key comparator type
    /// The actual object key comparator type (@ref object_comparator_t) may be
    /// different.
    /// @sa https://json.nlohmann.me/api/basic_json/default_object_comparator_t/
-#if defined(JSON_HAS_CPP_14)
    // use of transparent comparator avoids unnecessary repeated construction of temporaries
    // in functions involving lookup by key with types other than object_t::key_type (aka. StringType)
    using default_object_comparator_t = std::less<>;
 #else
+    /// @brief default object key comparator type
+    /// The actual object key comparator type (@ref object_comparator_t) may be
+    /// different.
+    /// @sa https://json.nlohmann.me/api/basic_json/default_object_comparator_t/
    using default_object_comparator_t = std::less<StringType>;
 #endif

@@ -1914,6 +1927,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
    // other constructors and destructor //
    ///////////////////////////////////////

+    /// @sa https://json.nlohmann.me/api/basic_json/basic_json/
    template<typename JsonRef,
             detail::enable_if_t<detail::conjunction<detail::is_json_ref<JsonRef>,
                                 std::is_same<typename JsonRef::value_type, basic_json>>::value, int> = 0 >
@@ -2497,6 +2511,8 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
    @throw what @ref json_serializer<ValueType> `from_json()` method throws if conversion is required

    @since version 2.1.0
+
+    @sa https://json.nlohmann.me/api/basic_json/get/
    */
    template < typename ValueTypeCV, typename ValueType = detail::uncvref_t<ValueTypeCV>>
 #if defined(JSON_HAS_CPP_14)
@@ -2540,6 +2556,8 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
    @sa see @ref get_ptr() for explicit pointer-member access

    @since version 1.0.0
+
+    @sa https://json.nlohmann.me/api/basic_json/get/
    */
    template<typename PointerType, typename std::enable_if<
                 std::is_pointer<PointerType>::value, int>::type = 0>
@@ -2566,6 +2584,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec

    // specialization to allow calling get_to with a basic_json value
    // see https://github.com/nlohmann/json/issues/2175
+    /// @sa https://json.nlohmann.me/api/basic_json/get_to/
    template<typename ValueType,
             detail::enable_if_t <
                 detail::is_basic_json<ValueType>::value,
@@ -2576,6 +2595,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        return v;
    }

+    /// @sa https://json.nlohmann.me/api/basic_json/get_to/
    template <
        typename T, std::size_t N,
        typename Array = T (&)[N], // NOLINT(cppcoreguidelines-avoid-c-arrays,hicpp-avoid-c-arrays,modernize-avoid-c-arrays)
@@ -2640,6 +2660,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec

    @since version 1.0.0
    */
+    /// @sa https://json.nlohmann.me/api/basic_json/operator_ValueType/
    template < typename ValueType, typename std::enable_if <
                   detail::conjunction <
                       detail::negation<std::is_pointer<ValueType>>,
@@ -2919,12 +2940,14 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec

    // these two functions resolve a (const) char * ambiguity affecting Clang and MSVC
    // (they seemingly cannot be constrained to resolve the ambiguity)
+    /// @sa https://json.nlohmann.me/api/basic_json/operator[]/
    template<typename T>
    reference operator[](T* key)
    {
        return operator[](typename object_t::key_type(key));
    }

+    /// @sa https://json.nlohmann.me/api/basic_json/operator[]/
    template<typename T>
    const_reference operator[](T* key) const
    {
@@ -3138,6 +3161,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        JSON_THROW(type_error::create(306, detail::concat("cannot use value() with ", type_name()), this));
    }

+    /// @sa https://json.nlohmann.me/api/basic_json/value/
    template < class ValueType, class BasicJsonType, detail::enable_if_t <
                   detail::is_basic_json<BasicJsonType>::value
                   && detail::is_getable<basic_json_t, ValueType>::value
@@ -3148,6 +3172,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        return value(ptr.convert(), default_value);
    }

+    /// @sa https://json.nlohmann.me/api/basic_json/value/
    template < class ValueType, class BasicJsonType, class ReturnType = typename value_return_type<ValueType>::type,
               detail::enable_if_t <
                   detail::is_basic_json<BasicJsonType>::value
@@ -3537,6 +3562,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        return ptr.contains(this);
    }

+    /// @sa https://json.nlohmann.me/api/basic_json/contains/
    template<typename BasicJsonType, detail::enable_if_t<detail::is_basic_json<BasicJsonType>::value, int> = 0>
    JSON_HEDLEY_WARN_UNUSED_RESULT
    JSON_HEDLEY_DEPRECATED_FOR(3.11.0, basic_json::json_pointer or nlohmann::json_pointer<basic_json::string_t>) // NOLINT(readability/alt_tokens)
@@ -4976,6 +5002,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        return result;
    }

+    /// @sa https://json.nlohmann.me/api/basic_json/parse/
    JSON_HEDLEY_WARN_UNUSED_RESULT
    JSON_HEDLEY_DEPRECATED_FOR(3.8.0, parse(ptr, ptr + len))
    static basic_json parse(detail::span_input_adapter&& i,
@@ -5012,6 +5039,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        return parser(detail::input_adapter(std::move(first), std::move(last)), nullptr, false, ignore_comments, ignore_trailing_commas, true).accept(true);
    }

+    /// @sa https://json.nlohmann.me/api/basic_json/accept/
    JSON_HEDLEY_WARN_UNUSED_RESULT
    JSON_HEDLEY_DEPRECATED_FOR(3.8.0, accept(ptr, ptr + len))
    static bool accept(detail::span_input_adapter&& i,
@@ -5398,6 +5426,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        return result;
    }

+    /// @sa https://json.nlohmann.me/api/basic_json/from_cbor/
    template<typename T>
    JSON_HEDLEY_WARN_UNUSED_RESULT
    JSON_HEDLEY_DEPRECATED_FOR(3.8.0, from_cbor(ptr, ptr + len))
@@ -5409,6 +5438,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        return from_cbor(ptr, ptr + len, strict, allow_exceptions, tag_handler);
    }

+    /// @sa https://json.nlohmann.me/api/basic_json/from_cbor/
    JSON_HEDLEY_WARN_UNUSED_RESULT
    JSON_HEDLEY_DEPRECATED_FOR(3.8.0, from_cbor(ptr, ptr + len))
    static basic_json from_cbor(detail::span_input_adapter&& i,
@@ -5464,6 +5494,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        return result;
    }

+    /// @sa https://json.nlohmann.me/api/basic_json/from_msgpack/
    template<typename T>
    JSON_HEDLEY_WARN_UNUSED_RESULT
    JSON_HEDLEY_DEPRECATED_FOR(3.8.0, from_msgpack(ptr, ptr + len))
@@ -5474,6 +5505,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        return from_msgpack(ptr, ptr + len, strict, allow_exceptions);
    }

+    /// @sa https://json.nlohmann.me/api/basic_json/from_msgpack/
    JSON_HEDLEY_WARN_UNUSED_RESULT
    JSON_HEDLEY_DEPRECATED_FOR(3.8.0, from_msgpack(ptr, ptr + len))
    static basic_json from_msgpack(detail::span_input_adapter&& i,
@@ -5528,6 +5560,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        return result;
    }

+    /// @sa https://json.nlohmann.me/api/basic_json/from_ubjson/
    template<typename T>
    JSON_HEDLEY_WARN_UNUSED_RESULT
    JSON_HEDLEY_DEPRECATED_FOR(3.8.0, from_ubjson(ptr, ptr + len))
@@ -5538,6 +5571,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        return from_ubjson(ptr, ptr + len, strict, allow_exceptions);
    }

+    /// @sa https://json.nlohmann.me/api/basic_json/from_ubjson/
    JSON_HEDLEY_WARN_UNUSED_RESULT
    JSON_HEDLEY_DEPRECATED_FOR(3.8.0, from_ubjson(ptr, ptr + len))
    static basic_json from_ubjson(detail::span_input_adapter&& i,
@@ -5666,6 +5700,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        return result;
    }

+    /// @sa https://json.nlohmann.me/api/basic_json/from_bson/
    template<typename T>
    JSON_HEDLEY_WARN_UNUSED_RESULT
    JSON_HEDLEY_DEPRECATED_FOR(3.8.0, from_bson(ptr, ptr + len))
@@ -5676,6 +5711,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        return from_bson(ptr, ptr + len, strict, allow_exceptions);
    }

+    /// @sa https://json.nlohmann.me/api/basic_json/from_bson/
    JSON_HEDLEY_WARN_UNUSED_RESULT
    JSON_HEDLEY_DEPRECATED_FOR(3.8.0, from_bson(ptr, ptr + len))
    static basic_json from_bson(detail::span_input_adapter&& i,
@@ -5708,6 +5744,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        return ptr.get_unchecked(this);
    }

+    /// @sa https://json.nlohmann.me/api/basic_json/operator%5B%5D/
    template<typename BasicJsonType, detail::enable_if_t<detail::is_basic_json<BasicJsonType>::value, int> = 0>
    JSON_HEDLEY_DEPRECATED_FOR(3.11.0, basic_json::json_pointer or nlohmann::json_pointer<basic_json::string_t>) // NOLINT(readability/alt_tokens)
    reference operator[](const ::nlohmann::json_pointer<BasicJsonType>& ptr)
@@ -5722,6 +5759,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        return ptr.get_unchecked(this);
    }

+    /// @sa https://json.nlohmann.me/api/basic_json/operator%5B%5D/
    template<typename BasicJsonType, detail::enable_if_t<detail::is_basic_json<BasicJsonType>::value, int> = 0>
    JSON_HEDLEY_DEPRECATED_FOR(3.11.0, basic_json::json_pointer or nlohmann::json_pointer<basic_json::string_t>) // NOLINT(readability/alt_tokens)
    const_reference operator[](const ::nlohmann::json_pointer<BasicJsonType>& ptr) const
@@ -5736,6 +5774,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        return ptr.get_checked(this);
    }

+    /// @sa https://json.nlohmann.me/api/basic_json/at/
    template<typename BasicJsonType, detail::enable_if_t<detail::is_basic_json<BasicJsonType>::value, int> = 0>
    JSON_HEDLEY_DEPRECATED_FOR(3.11.0, basic_json::json_pointer or nlohmann::json_pointer<basic_json::string_t>) // NOLINT(readability/alt_tokens)
    reference at(const ::nlohmann::json_pointer<BasicJsonType>& ptr)
@@ -5750,6 +5789,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
        return ptr.get_checked(this);
    }

+    /// @sa https://json.nlohmann.me/api/basic_json/at/
    template<typename BasicJsonType, detail::enable_if_t<detail::is_basic_json<BasicJsonType>::value, int> = 0>
    JSON_HEDLEY_DEPRECATED_FOR(3.11.0, basic_json::json_pointer or nlohmann::json_pointer<basic_json::string_t>) // NOLINT(readability/alt_tokens)
    const_reference at(const ::nlohmann::json_pointer<BasicJsonType>& ptr) const
@@ -32,30 +32,41 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
 {
    using key_type = Key;
    using mapped_type = T;
+    /// @sa https://json.nlohmann.me/api/ordered_map/Container/
    using Container = std::vector<std::pair<const Key, T>, Allocator>;
    using iterator = typename Container::iterator;
    using const_iterator = typename Container::const_iterator;
    using size_type = typename Container::size_type;
    using value_type = typename Container::value_type;
 #ifdef JSON_HAS_CPP_14
+    /// @sa https://json.nlohmann.me/api/ordered_map/key_compare/
    using key_compare = std::equal_to<>;
 #else
+    /// @sa https://json.nlohmann.me/api/ordered_map/key_compare/
    using key_compare = std::equal_to<Key>;
 #endif

    // Explicit constructors instead of `using Container::Container`
    // otherwise older compilers choke on it (GCC <= 5.5, xcode <= 9.4)
+    /// @sa https://json.nlohmann.me/api/ordered_map/ordered_map/
    ordered_map() noexcept(noexcept(Container())) : Container{} {}
+    /// @sa https://json.nlohmann.me/api/ordered_map/ordered_map/
    explicit ordered_map(const Allocator& alloc) noexcept(noexcept(Container(alloc))) : Container{alloc} {}
+    /// @sa https://json.nlohmann.me/api/ordered_map/ordered_map/
    template <class It>
    ordered_map(It first, It last, const Allocator& alloc = Allocator())
        : Container{first, last, alloc} {}
+    /// @sa https://json.nlohmann.me/api/ordered_map/ordered_map/
    ordered_map(std::initializer_list<value_type> init, const Allocator& alloc = Allocator() )
        : Container{init, alloc} {}
+    /// @sa https://json.nlohmann.me/api/ordered_map/ordered_map/
    ordered_map(const ordered_map&) = default;
+    /// @sa https://json.nlohmann.me/api/ordered_map/ordered_map/
    ordered_map(ordered_map&&) noexcept(std::is_nothrow_move_constructible<Container>::value) = default;
+    /// @sa https://json.nlohmann.me/api/ordered_map/~ordered_map/
    ~ordered_map() = default;

+    /// @sa https://json.nlohmann.me/api/ordered_map/operator=/
    ordered_map& operator=(const ordered_map& other)
    {
        if (this != &other)
@@ -66,12 +77,14 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
        return *this;
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/operator=/
    ordered_map& operator=(ordered_map&& other) noexcept(std::is_nothrow_move_assignable<Container>::value)
    {
        Container::operator=(std::move(static_cast<Container&>(other)));
        return *this;
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/emplace/
    std::pair<iterator, bool> emplace(const key_type& key, T&& t)
    {
        for (auto it = this->begin(); it != this->end(); ++it)
@@ -85,6 +98,7 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
        return {std::prev(this->end()), true};
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/emplace/
    template<class KeyType, detail::enable_if_t<
                 detail::is_usable_as_key_type<key_compare, key_type, KeyType>::value, int> = 0>
    std::pair<iterator, bool> emplace(KeyType && key, T && t)
@@ -100,11 +114,13 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
        return {std::prev(this->end()), true};
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/operator[]/
    T& operator[](const key_type& key)
    {
        return emplace(key, T{}).first->second;
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/operator[]/
    template<class KeyType, detail::enable_if_t<
                 detail::is_usable_as_key_type<key_compare, key_type, KeyType>::value, int> = 0>
    T & operator[](KeyType && key)
@@ -112,11 +128,13 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
        return emplace(std::forward<KeyType>(key), T{}).first->second;
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/operator[]/
    const T& operator[](const key_type& key) const
    {
        return at(key);
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/operator[]/
    template<class KeyType, detail::enable_if_t<
                 detail::is_usable_as_key_type<key_compare, key_type, KeyType>::value, int> = 0>
    const T & operator[](KeyType && key) const
@@ -124,6 +142,7 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
        return at(std::forward<KeyType>(key));
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/at/
    T& at(const key_type& key)
    {
        for (auto it = this->begin(); it != this->end(); ++it)
@@ -137,6 +156,7 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
        JSON_THROW(std::out_of_range("key not found"));
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/at/
    template<class KeyType, detail::enable_if_t<
                 detail::is_usable_as_key_type<key_compare, key_type, KeyType>::value, int> = 0>
    T & at(KeyType && key) // NOLINT(cppcoreguidelines-missing-std-forward)
@@ -152,6 +172,7 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
        JSON_THROW(std::out_of_range("key not found"));
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/at/
    const T& at(const key_type& key) const
    {
        for (auto it = this->begin(); it != this->end(); ++it)
@@ -165,6 +186,7 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
        JSON_THROW(std::out_of_range("key not found"));
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/at/
    template<class KeyType, detail::enable_if_t<
                 detail::is_usable_as_key_type<key_compare, key_type, KeyType>::value, int> = 0>
    const T & at(KeyType && key) const // NOLINT(cppcoreguidelines-missing-std-forward)
@@ -180,6 +202,7 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
        JSON_THROW(std::out_of_range("key not found"));
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/erase/
    size_type erase(const key_type& key)
    {
        for (auto it = this->begin(); it != this->end(); ++it)
@@ -199,6 +222,7 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
        return 0;
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/erase/
    template<class KeyType, detail::enable_if_t<
                 detail::is_usable_as_key_type<key_compare, key_type, KeyType>::value, int> = 0>
    size_type erase(KeyType && key) // NOLINT(cppcoreguidelines-missing-std-forward)
@@ -220,11 +244,13 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
        return 0;
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/erase/
    iterator erase(iterator pos)
    {
        return erase(pos, std::next(pos));
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/erase/
    iterator erase(iterator first, iterator last)
    {
        if (first == last)
@@ -278,6 +304,7 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
        return Container::begin() + offset;
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/count/
    size_type count(const key_type& key) const
    {
        for (auto it = this->begin(); it != this->end(); ++it)
@@ -290,6 +317,7 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
        return 0;
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/count/
    template<class KeyType, detail::enable_if_t<
                 detail::is_usable_as_key_type<key_compare, key_type, KeyType>::value, int> = 0>
    size_type count(KeyType && key) const // NOLINT(cppcoreguidelines-missing-std-forward)
@@ -304,6 +332,7 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
        return 0;
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/find/
    iterator find(const key_type& key)
    {
        for (auto it = this->begin(); it != this->end(); ++it)
@@ -316,6 +345,7 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
        return Container::end();
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/find/
    template<class KeyType, detail::enable_if_t<
                 detail::is_usable_as_key_type<key_compare, key_type, KeyType>::value, int> = 0>
    iterator find(KeyType && key) // NOLINT(cppcoreguidelines-missing-std-forward)
@@ -330,6 +360,7 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
        return Container::end();
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/find/
    const_iterator find(const key_type& key) const
    {
        for (auto it = this->begin(); it != this->end(); ++it)
@@ -342,6 +373,7 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
        return Container::end();
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/find/
    template<class KeyType, detail::enable_if_t<
                 detail::is_usable_as_key_type<key_compare, key_type, KeyType>::value, int> = 0>
    const_iterator find(KeyType && key) const // NOLINT(cppcoreguidelines-missing-std-forward)
@@ -356,11 +388,13 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
        return Container::end();
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/insert/
    std::pair<iterator, bool> insert( value_type&& value )
    {
        return emplace(value.first, std::move(value.second));
    }

+    /// @sa https://json.nlohmann.me/api/ordered_map/insert/
    std::pair<iterator, bool> insert( const value_type& value )
    {
        for (auto it = this->begin(); it != this->end(); ++it)
@@ -378,6 +412,7 @@ template <class Key, class T, class IgnoredLess = std::less<Key>,
    using require_input_iter = typename std::enable_if<std::is_convertible<typename std::iterator_traits<InputIt>::iterator_category,
        std::input_iterator_tag>::value>::type;

+    /// @sa https://json.nlohmann.me/api/ordered_map/insert/
    template<typename InputIt, typename = require_input_iter<InputIt>>
    void insert(InputIt first, InputIt last)
    {
@@ -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},
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-            {"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
@@ -13,18 +13,15 @@
 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 <map> // map
 #include <sstream> // stringstream
 #include <string> // string
 #include <utility> // pair
 #include <vector> // vector

-#include "float_hard_cases.hpp"
-
 namespace
 {
 // shortcut to scan a string literal
@@ -260,7 +257,7 @@ 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"
        };
@@ -282,18 +279,20 @@ 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
@@ -664,145 +663,46 @@ TEST_CASE("lexer string fast path")
    }
 }

-namespace
+TEST_CASE("parse_float_fast declines what it cannot convert exactly")
 {
-// 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)
+    // 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)
    {
-        if (s[i] == '.')
-        {
-            dot = i;
-        }
-        else if (s[i] == 'e' || s[i] == 'E')
-        {
-            mantissa_end = i;
-            break;
-        }
-    }
-    return {dot, mantissa_end};
-}
+        return nlohmann::detail::parse_float_fast(s.data(), s.data() + s.size(), out);
+    };
+    double out = 0;

-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);
-}
+#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

-std::uint64_t bits_of(double d)
-{
-    std::uint64_t b = 0;
-    std::memcpy(&b, &d, sizeof(b));
-    return b;
-}
+    // 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));

-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
@@ -906,6 +806,40 @@ 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")
@@ -1303,33 +1237,26 @@ 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;
@@ -1351,51 +1278,30 @@ 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")
@@ -1409,177 +1315,3 @@ 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);
-    }
-}
@@ -257,11 +257,10 @@ 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)
@@ -325,8 +324,7 @@ 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
@@ -352,15 +350,8 @@ 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)
@@ -378,20 +369,12 @@ 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);
    }
@@ -0,0 +1,127 @@
+# Public API Policy
+
+This document defines what counts as the **public API** of nlohmann/json for the purposes of the
+`tools/api_checker/` tooling, what stability is (and is not) guaranteed, and how API changes are
+classified as breaking or feature additions. It exists so that "public API" is a checkable, mechanical
+property of the source, not a matter of convention or memory — see
+[Discussion #3691](https://github.com/nlohmann/json/discussions/3691) for the original motivation.
+
+## What counts as public API
+
+The public API surface is derived from C++ semantics (class templates, access specifiers, namespace
+scoping) by `extract_api.py`, not from the presence of documentation. It consists of:
+
+1. **Public members of six class templates**: `basic_json`, `adl_serializer`,
+   `byte_container_with_subtype`, `json_pointer`, `json_sax`, `ordered_map`. Specifically, the *primary
+   template definition* (`CLASS_TEMPLATE` cursor with `is_definition() == True`) — never an implicit
+   instantiation, which silently drops SFINAE-guarded overloads. Two tiers apply:
+   - **Callable tier** (methods, constructors, destructors, conversion operators, function templates):
+     every public callable requires its own `@sa` documentation link, without exception.
+   - **Type tier** (public type aliases): requires `@sa`, except for a fixed exemption list of
+     STL-container named-requirement aliases that mirror standard-library conventions rather than being
+     independently documented: `value_type`, `reference`, `const_reference`, `pointer`, `const_pointer`,
+     `iterator`, `const_iterator`, `reverse_iterator`, `const_reverse_iterator`, `difference_type`,
+     `size_type`, `allocator_type`, `key_type`, `mapped_type`. This list is defined once, in
+     `extract_api.py`'s `stl_exempt` set, and referenced here rather than duplicated.
+2. **Free functions and operators in `nlohmann::`**, including `nlohmann::literals::json_literals`
+   (the `operator""_json` / `operator""_json_pointer` user-defined literals). Comparison and stream
+   operators on `basic_json` and `json_pointer`, `operator/`, `swap`.
+3. **The six alias-exposed exception types**: `basic_json::exception`, `parse_error`,
+   `invalid_iterator`, `type_error`, `out_of_range`, `other_error`. These are public `TYPE_ALIAS_DECL`s
+   in `basic_json` (e.g. `using exception = detail::exception;`) whose underlying class is physically
+   defined in `nlohmann::detail::exceptions.hpp`. `extract_api.py` follows the alias to find the `@sa` on
+   the underlying `detail::` class definition, since that's where the existing documentation convention
+   places it. Each exception class is documented as *one page* — its individual members (`what()`, `id`)
+   are not separately tracked, matching the existing one-page-per-class convention.
+4. **Macros**, governed separately by `docs/mkdocs/docs/api/macros/` (the curated list of ~30 pages is
+   authoritative) and cross-checked, advisory-only, by `check_macros.py`. See "Known limitations" below
+   for why macros can't be checked the same way as everything else.
+
+## What's excluded
+
+- **Everything in `nlohmann::detail::`**, with the one narrow exception above (exception-type aliases).
+  **No stability is guaranteed for any symbol in the `detail::` namespace — clients must not rely on it**,
+  regardless of whether a given `detail::` symbol happens to be reachable from user code today. This is
+  an explicit, deliberate policy, not an oversight.
+- **Private and protected members**, even of the six tracked classes. `extract_api.py` walks non-public
+  members only to check they don't carry a stray `@sa` (a documentation leak) — never to add them to the
+  public surface.
+- **The ABI inline-namespace segment** (`json_abi_v3_12_0`, `json_abi_diag_v3_12_0`, etc. — see
+  [docs/mkdocs/docs/features/namespace.md](../../docs/mkdocs/docs/features/namespace.md)). This is a
+  version-tag identity concern for `diff_api.py` (it must not make every release look like the entire API
+  was removed and re-added), not a scoping or visibility concern — the symbols inside it are public or
+  not independent of the tag.
+
+## Breaking vs. feature classification
+
+`diff_api.py` compares the `public_api` surface of two snapshots using an overload-disambiguating
+identity — `(scope, identity_name, kind, signature)`, where `signature` is the declaration's own
+source text (return type, name, parameter list, trailing qualifiers; comments and constructors'
+member-initializer-lists stripped). This is the third identity scheme this tooling has used; the
+first two were each found broken by testing against real release tags, not by inspection — see
+`extract_api.py`'s `identity_key()` docstring for the full history (a naive params-only key silently
+collided on overloads differing only by constness/SFINAE; libclang's USR fixed that but encoded the
+*enclosing class template's own arity*, so a single backward-compatible template-parameter addition
+made ~228 of 330 `basic_json` entries look "changed" between two real releases with zero actual
+breaking changes among them).
+
+- An identity present only in the **new** snapshot → **feature** (addition).
+- An identity present only in the **old** snapshot → **breaking** (removal).
+- The same `(scope, name)` with one identity removed and a different one added → reported as a
+  **changed overload**, classified breaking by default. No automatic overload-compatibility reasoning
+  is attempted — whether a signature change is source-compatible is a judgment call for a human
+  reviewer, not a sound problem for a CI tool to solve unsupervised.
+
+## Stable per-release API history
+
+`tools/api_checker/history/<tag>.json` holds one immutable, committed API-surface record per
+released `v3.*` tag (captured via `snapshot_release.py`; see `tools/api_checker/README.md` and
+`tools/api_checker/history/README.md`). `diff_api.py` reads from here automatically when a ref
+matches a stored file, instead of live-extracting via `git archive` every time.
+
+Every surface file (the live `api_surface.json` and every `history/*.json` record) carries a
+`format_version` integer. **Bump it whenever a change to the schema, or to the identity-computing
+algorithm (`get_signature_text()`/`get_identity_name()`/`identity_key()` in `extract_api.py`), could
+alter the `signature` or `identity_name` text for otherwise-unchanged source.** `diff_api.py` refuses
+by default to compare two surfaces with different `format_version` values — this is a direct,
+mechanical safeguard against the exact class of bug that motivated the current identity scheme (see
+above): a silent algorithm change corrupting every historical comparison with no way to detect it.
+An explicit `--allow-format-mismatch` flag exists for a deliberate, informed comparison anyway.
+
+Practical implication for anyone changing `extract_api.py`'s identity logic: bump
+`SURFACE_FORMAT_VERSION`, and treat every already-committed `history/*.json` file as needing a
+`--force` regeneration (reviewed, not blind) before it can be meaningfully compared against surfaces
+produced by the new algorithm version.
+
+## Stability guarantees
+
+This tooling makes the project's existing commitments *mechanically checkable* — it does not introduce a
+new promise:
+
+- `ChangeLog.md` states the project "adheres to [Semantic Versioning](http://semver.org/)."
+- [docs/mkdocs/docs/home/releases.md](../../docs/mkdocs/docs/home/releases.md) marks every 3.x release "All
+  changes are backward-compatible" (except 3.0.0 itself, a major bump with a migration guide).
+- `tests/abi/` provides a complementary, narrower guarantee: ABI/link compatibility *within one ABI tag*.
+  That is a binary-compatibility concern; this tooling's concern is source/API-level — a symbol can be
+  ABI-stable and still be a source-breaking change (e.g. a removed overload), or vice versa.
+
+## Known limitations
+
+- **Macros have no C++ access-specifier concept**, so the public/private test that works for classes
+  doesn't transfer. Only a minority of documented macro `#define`s have an attached `@sa`-style comment
+  (the `#ifndef X / #define X value #endif` idiom has no natural comment-attachment point), and internal
+  helper macros live in the same files as public configuration macros, so no path-based exclusion works
+  either. `check_macros.py` therefore only checks one direction: that every documented macro still has a
+  matching `#define` somewhere under `include/nlohmann/` (catches stale/renamed doc pages). It does
+  **not** attempt to detect undocumented macros — no reliable signal exists for that direction with the
+  current codebase conventions, and this tool doesn't pretend otherwise.
+- **`diff_api.py` does not track exception specifications or template-parameter-only changes.** A
+  function whose `noexcept` status changes, or whose template parameter list changes without altering
+  its externally-visible identity, will not be flagged.
+- **Known API-hygiene gap, surfaced by this tooling rather than fixed**:
+  `basic_json::insert_iterator` (a `public` member per C++ access rules) is a helper used internally by
+  `insert()`; its own source comment calls it "Helper for insertion of an iterator." It has no
+  documentation page and is deliberately left undocumented rather than either speculatively documented or
+  silently exempted — this is exactly the class of undocumented-and-probably-shouldn't-be-public symbol
+  this tooling exists to surface, per the motivating discussion. A future PR may reclassify it as private
+  as a (breaking, ABI-relevant) cleanup; that is out of scope here.
--- a/Show More
+++ b/Show More
Author	SHA1	Message	Date
Niels Lohmann	9196e92520	Merge branch 'develop' into claude/todo-191-plan-508110 Conflicts: none textual. Follow-up fixes for develop's changes: - docs/mkdocs/docs/api/ordered_map/index.md: develop's new paragraph (#5609) was written for api/ordered_map.md; fixed its relative ordered_json.md link for the page's new location, plus two pre-existing links from an earlier merge (ordered_json.md, features/object_order.md) - tools/api_checker/api_surface.json: regenerated with libclang 18.1.1 on Linux (swap() noexcept now includes json_base_class_t; new integral-key contains/count/find/value overloads) Signed-off-by: Niels Lohmann <mail@nlohmann.me>	2026-09-30 20:36:12 +02:00
Niels Lohmann	7d22d865dd	Merge branch 'develop' into claude/todo-191-plan-508110 Signed-off-by: Niels Lohmann <mail@nlohmann.me>	2026-09-28 22:22:46 +02:00
Niels Lohmann	4c73319d3b	Use one-line module docstrings in the API checker scripts Codacy runs two docstring checkers with opposite rules for module docstrings: with the summary on the first line it reported D213, with the summary on the second line it reports D212. A one-line docstring satisfies both. Keep the summary as the docstring and move the details into a comment below it; nothing reads the module docstrings. Signed-off-by: Niels Lohmann <mail@nlohmann.me>	2026-09-28 18:42:34 +02:00
Niels Lohmann	da5097abcd	Restore the CI spelling of json_pointer's operator string_t in the API surface The develop merge regenerated api_surface.json on macOS, whose libclang spells the name of the deprecated conversion operator as "operator nlohmann::json_pointer::string_t_helper<...>::type". CI's pinned libclang 18.1.1 on Linux spells it "operator typename string_t_helper<...>::type", so check_api_docs reported the file as out of date. This restores CI's spelling, which is byte-identical to the file CI regenerated. Signed-off-by: Niels Lohmann <mail@nlohmann.me>	2026-09-27 21:37:14 +02:00
Niels Lohmann	2319f6e6f9	Address Codacy findings in the API checker scripts Put multi-line docstring summaries on their own line, as a single sentence followed by a blank line (pydocstyle D205, D209, D213, D415). Annotate the subprocess import and calls with nosec: they only run fixed argument lists, never through a shell (Bandit B404, B603, B607). Do the same for the three broad except clauses in extract_api.py, which deliberately fall through to the next libclang candidate or skip an unresolvable alias (Bandit B110, B112). Signed-off-by: Niels Lohmann <mail@nlohmann.me>	2026-09-27 18:09:03 +02:00
Niels Lohmann	9a0d1c0c47	Merge branch 'develop' into claude/todo-191-plan-508110 Resolve the conflict in docs/mkdocs/docs/home/architecture.md by taking develop's rewritten page and pointing its ordered_map links at the moved api/ordered_map/index.md. Also update the ordered_map.md links develop added in ordered_json.md, object_order.md, and template_parameters.md. Regenerate api_surface.json for the new BON8 functions and the changed comparison operator. Restrict the documented_non_public leak check to @sa URLs into json.nlohmann.me: develop now uses @sa to link GitHub issues from private members such as copy_structured, which is not a documentation leak. Signed-off-by: Niels Lohmann <mail@nlohmann.me>	2026-09-27 18:07:00 +02:00
Niels Lohmann	1bbb5d400a	Regenerate api_surface.json after merging develop develop added JSON_HEDLEY_WARN_UNUSED_RESULT to a number of basic_json members (#5520) and reworked operator<<'s output adapter, so the committed API surface no longer matched what extract_api.py produces and the "Check for uncommitted API surface changes" step failed. This is the patch the workflow itself uploads for that purpose; the changes are limited to recorded signatures plus the way libclang spells json_pointer's conversion operator. Signed-off-by: Niels Lohmann <mail@nlohmann.me>	2026-09-15 10:06:55 +02:00
Niels Lohmann	08d18d5a82	Merge remote-tracking branch 'origin/develop' into HEAD	2026-09-14 21:26:29 +02:00
Niels LohmannandClaude Sonnet 5	a27065bd12	Regenerate api_surface.json after merging develop develop gained iterator+sentinel support for accept()/parse()/sax_parse()/ from_cbor()/from_msgpack()/from_ubjson()/from_bjdata()/from_bson() (#5205) since this branch was created, which check_api_docs.yml's drift check caught immediately: GitHub's pull_request trigger checks out the PR-vs-base merge commit, not the PR branch in isolation, so CI was comparing the committed api_surface.json (generated before that upstream change existed) against a fresh extraction of a json.hpp that already had it. This superseded an earlier, incorrect diagnosis of the same symptom (a JSON_HAS_RANGES cross-environment pin) -- that fix remains in place since it's still a real, independent determinism improvement for three other JSON_HAS_RANGES-gated locations in type_traits.hpp, but it wasn't the actual cause of this particular mismatch: these new overloads turned out to be unconditional (SFINAE-gated via can_compare_ne, not preprocessor-gated), so no environment-detection difference was involved here at all. Signed-off-by: Niels Lohmann <mail@nlohmann.me> Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com> Signed-off-by: Niels Lohmann <mail@nlohmann.me>	2026-07-11 23:45:46 +02:00
Niels Lohmann	3940f4b730	Merge remote-tracking branch 'origin/develop' into claude/todo-191-plan-508110	2026-07-11 23:43:30 +02:00
Niels LohmannandClaude Sonnet 5	0663907b68	Fix cross-environment API-surface drift and lint findings from CI extract_api.py's own extraction wasn't deterministic across machines, which CI's drift check caught immediately: JSON_HAS_RANGES auto-detects via the standard library's __cpp_lib_ranges feature-test macro, which isn't reliably gated to C++20 mode by every stdlib -- undefined under -std=c++17 with macOS's libc++, but defined under the identical flag with the Ubuntu stdlib CI uses, so parse()/accept()/from_*() extracted different signatures purely depending on which machine ran the extraction. Pinned to -DJSON_HAS_RANGES=0: the deterministic and safe choice, since pinning to 1 was tried first and found to fail to parse on a stdlib without full <ranges> support even when the macro claims otherwise. Also found and fixed a second, independent source of the same class of drift: get_identity_name() used cursor.spelling verbatim for CONVERSION_FUNCTION cursors, which libclang renders as its own internally-canonicalized form of the return type rather than what's literally written. Confirmed for json_pointer::operator string_t() spelling differently on two machines pinned to the identical libclang==18.1.1 wheel, with the JSON_HAS_RANGES fix above ruled out as the cause. Now derived from the cursor's own raw source text instead, immune to libclang's dependent-type resolution differences and incidentally more readable than the libclang-internal forms it replaces. Bumped SURFACE_FORMAT_VERSION to 3 and regenerated all 27 history snapshots and the committed api_surface.json; both fixes are documented in tools/api_checker/history/README.md's format-history log. Also fixes diff_api.py's format_version guard, which only compared the two loaded surfaces against each other and never against SURFACE_FORMAT_VERSION (what this build actually understands) -- two surfaces on the same, newer-than-expected format_version would have silently passed the guard. Remaining fixes are the concretely actionable findings from Codacy's review of the new tools/api_checker/ files: unused imports/variables, a stray f-string with no placeholders. Left the docstring-formatting nitpicks (pydocstyle D2xx/D4xx) and generic subprocess-usage notices alone -- the former has no established convention elsewhere in this codebase's Python tooling to conform to, and the latter are inherent to a dev tool that shells out to git/clang with developer-controlled arguments, not user input. Signed-off-by: Niels Lohmann <mail@nlohmann.me> Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com> Signed-off-by: Niels Lohmann <mail@nlohmann.me>	2026-07-11 18:59:19 +02:00
Niels LohmannandClaude Sonnet 5	f23b3c63a2	Add AST-based public API checker and fix documentation gaps it found (#3691 ) Adds tools/api_checker/: extract_api.py derives the public API surface directly from the libclang AST (independent of documentation status), check_docs.py flags public entries missing @sa links (and @sa on non-public ones), diff_api.py does an overload-aware breaking/feature diff between two refs, check_macros.py cross- checks documented macros against #define sites, and snapshot_release.py backfills immutable per-release surface snapshots into tools/api_checker/history/ (v3.1.0 through v3.12.0) so diff_api.py can compare releases without live extraction. POLICY.md documents what counts as public API and what stability is guaranteed. Running this tooling against the current tree found and fixed a real documentation backlog: ~25 new API doc pages (ordered_map's methods, json_sax's ctor/dtor/ operator=, byte_container_with_subtype's comparison operators, several orphaned type aliases), each with a compiled and output-verified example, plus missing @sa comments and stale/incorrect Version History entries on several existing pages (found by diffing consecutive release pairs and checking whether the resulting change was actually reflected in the target page's history section). Also adds docs/home/api_changes.md, a per-release, per-function reference of public API changes (v3.1.0 through v3.12.0) generated from the history/ snapshots, complementing (not replacing) the existing release notes. Along the way, found and fixed several extractor bugs by testing against real release tags rather than trusting the algorithm in isolation -- most notably an identity-key scheme based on libclang's USR that encoded the enclosing class template's own arity, and a since-renamed ABI inline-namespace pattern (json_v3_11_0 vs. today's json_abi_v3_11_2) that neither of two earlier regex attempts stripped correctly. Both are documented in extract_api.py's docstrings and tools/api_checker/history/README.md so the failure mode doesn't recur silently. .github/workflows/check_api_docs.yml runs extract_api.py + check_docs.py in CI, advisory-only for now (documented backlog may not be at zero for entities this PR didn't touch), plus a blocking drift check on the committed tools/api_checker/api_surface.json. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com> Signed-off-by: Niels Lohmann <mail@nlohmann.me>	2026-07-11 18:59:00 +02:00
				`@@ -0,0 +1 @@`
				`Container is std::vector<std::pair<const Key, T>>: true`