Commit Graph
5300 Commits
Author SHA1 Message Date
Niels Lohmann 92bf5fbfb1 Merge branch 'json-view/19-edit-set' into json-view/21-images
Signed-off-by: Niels Lohmann <mail@nlohmann.me>

# Conflicts:
#	include/nlohmann/detail/view/document_data.hpp
#	single_include/nlohmann/json_view.hpp
2026-10-08 16:37:29 +02:00
Niels Lohmann 9962b3cf43 Merge branch 'json-view/16-view-simd' into json-view/19-edit-set
Signed-off-by: Niels Lohmann <mail@nlohmann.me>

# Conflicts:
#	include/nlohmann/detail/view/document_data.hpp
#	single_include/nlohmann/json_view.hpp
2026-10-08 16:33:54 +02:00
Niels Lohmann 4f1c34e44d Merge branch 'json-view/13-view-dump' into json-view/16-view-simd
Signed-off-by: Niels Lohmann <mail@nlohmann.me>

# Conflicts:
#	include/nlohmann/detail/view/document_data.hpp
#	single_include/nlohmann/json_view.hpp
2026-10-08 16:29:14 +02:00
Niels Lohmann 5db2fa633c Merge branch 'json-view/11-view-access' into json-view/13-view-dump
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-08 16:27:26 +02:00
Niels Lohmann acde46421b Merge branch 'json-view/08-view-builder' into json-view/11-view-access
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-08 16:27:24 +02:00
Niels Lohmann 30417e9e74 Exclude libstdc++'s string_view comparison from the sign-change check
basic_string_view::_S_compare stores the difference of two lengths in a
signed difference_type on purpose, which -fsanitize=integer reports for
every comparison with a shorter view (test-json_view_cpp17).

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-08 16:27:15 +02:00
Niels Lohmann 63396cbe00 Merge branch 'json-view/23-zmij' into json-view/08-view-builder
Signed-off-by: Niels Lohmann <mail@nlohmann.me>

# Conflicts:
#	Makefile
#	meson.build
2026-10-08 16:26:33 +02:00
Niels Lohmann d9a0844723 Fix document_data for old Clang (3.4-3.6)
Drop the empty braced NSDMIs of the std::string members: old Clang
rejects the defaulted constructor when it is used by a member
initializer before the end of the class definition.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-08 16:25:45 +02:00
Niels Lohmann 22b82b487b Merge branch 'json-view/02b-float-parser' into json-view/23-zmij
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-08 16:25:42 +02:00
Niels Lohmann 9c7eb12918 Fix GCC module build and MSVC C4127 in the json_view SIMD code
GCC ignores the target attribute in modules, so the SSSE3 dispatch is
disabled for the module interface (the check stays portable, SSE2 is kept).
Make the 8-vs-16 byte unrolling condition in scan_string_run a
preprocessor/template split to avoid a constant condition (C4127).

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-08 16:23:21 +02:00
Niels Lohmann 818ec541d9 Fix MSVC errors in image test and add image_check doc anchor
Move the raw string literal out of the CHECK macro (MSVC preprocessor),
cast 64-bit header fields to std::size_t (C4244 on 32-bit), and give the
image_check section in load.md a real anchor for the mkdocs strict build.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-08 16:22:58 +02:00
Niels Lohmann 2105149798 Fix old clang and MSVC C4127 in editable json documents
Value-initialize the const std::less in find_parent (clang 3.4/3.6 do not
implement DR 253), and test the Editable template argument through a
function to avoid MSVC C4127.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-08 16:22:47 +02:00
Niels Lohmann a7de414ce8 Avoid raw string with escapes inside CHECK macro (MSVC C2017)
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-08 16:19:11 +02:00
Niels Lohmann 43c75bef51 Merge branch 'develop' into json-view/02b-float-parser
Signed-off-by: Niels Lohmann <mail@nlohmann.me>

# Conflicts:
#	tests/src/unit-class_lexer.cpp
2026-10-08 16:19:06 +02:00
Niels Lohmann 3d7f554927 Use the with_*_t aliases in tests, examples, and docs (#5787)
* Use the with_*_t aliases in tests, examples, and docs

Replace spelled-out basic_json<...> instantiations that only change one
or two template parameters with nlohmann::json::with_*_t (or
ordered_json::with_*_t when the object type is ordered_map). Types that
change all three number types chain with_integers_t and with_float_t.

The raw basic_json<...> spelling stays where the template parameter
list itself is the subject: the alias tests in unit-udt.cpp, explicit
instantiations, and the ordered_json/compile-time docs.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Fix unit-large_json for clang and JSON_DIAGNOSTICS

Two test problems from #5781 broke CI on develop: CAPTURE(depth); trips
clang's -Wextra-semi-stmt, and the type_error.321 messages did not
account for the diagnostics path prefix.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Use static_cast in unit-hash for clang-tidy

#5772 added functional casts that clang-tidy reports as C-style casts
(google-readability-casting). Also append a char instead of a
one-character string in unit-large_json.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Declare the expected message prefix const in unit-large_json

Without JSON_DIAGNOSTICS the prefix was never modified, which
clang-tidy reports (misc-const-correctness).

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

---------

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-08 16:11:16 +02:00
Suyog Verma a269794db7 Use MSVC intrinsics for full multiplication (#5782)
* Use MSVC intrinsics for full multiplication

Signed-off-by: Suyog Verma <suyogverma0057@gmail.com>

* Fix formatting in unit-class_lexer

Signed-off-by: Suyog Verma <suyogverma0057@gmail.com>

* Address review feedback

Signed-off-by: Suyog Verma <suyogverma0057@gmail.com>

---------

Signed-off-by: Suyog Verma <suyogverma0057@gmail.com>
2026-10-08 08:49:32 +02:00
Niels LohmannandDylan Baker ed8ba0201f Install CMake package config files with Meson, and add Meson options (#5587)
* Install CMake package config files with Meson, and add Meson options

Squashed onto develop from:
- Install CMake package config files with Meson
- meson: Indent code inside an if block
- meson: set a minimum Meson version
- meson: use `override_dependency()` to set dependencies
- meson: use `install_subdir` for headers
- meson: set the C++ standard to C++11
- meson: handle single header and multiheader the same way CMake does
- meson: add support for the GlobalUDLs option
- meson: add support for the ImplictConversions option
- Add meson information to FILES.md
- Complete the Meson options and match CMake's compile definitions
- Add the JSON_* definitions to the CMake pkg-config file
- Document the Meson options and check them in CI
- Fix the Meson CMake target for includedir or datadir outside the prefix
- Avoid //include in Meson-generated CMake target for prefix /
- Add DisableTupleReferenceConversion to Meson and the CMake pkg-config file
- Check in CI that Meson and pkg-config offer the CMake options
- Remove accidentally committed Python bytecode

Co-authored-by: Dylan Baker <dylan@pnwbakers.com>
Signed-off-by: Dylan Baker <dylan@pnwbakers.com>
Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Add the StrictBinaryUTF8 and DeleteDeprecatedFunctions Meson options

JSON_StrictBinaryUTF8 (#5741) and JSON_DeleteDeprecatedFunctions (#5755)
arrived with develop but were missing from the Meson build and the
pkg-config file, so check_build_options failed. Both Meson options
default to false and add JSON_STRICT_BINARY_UTF8=1 and
JSON_DELETE_DEPRECATED_FUNCTIONS=1 to the dependency, the pkg-config
file, and the generated CMake target; CMake's pkg-config file now
carries both definitions too. The ci_meson_install job sets and checks
them in its non-default install.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

---------

Signed-off-by: Dylan Baker <dylan@pnwbakers.com>
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
Co-authored-by: Dylan Baker <dylan@pnwbakers.com>
2026-10-07 22:20:05 +02:00
Niels Lohmann c7138cc9b4 Merge branch 'json-view/19-edit-set' into json-view/21-images
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-07 20:26:55 +02:00
Niels Lohmann 0a4c6d1a8f Merge branch 'json-view/16-view-simd' into json-view/19-edit-set
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-07 20:26:52 +02:00
Niels Lohmann ad715372bf Merge branch 'json-view/13-view-dump' into json-view/16-view-simd
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-07 20:26:50 +02:00
Niels Lohmann c39680779c Merge branch 'json-view/11-view-access' into json-view/13-view-dump
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-07 20:26:47 +02:00
Niels Lohmann dfdd69d234 Merge branch 'json-view/08-view-builder' into json-view/11-view-access
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-07 20:26:44 +02:00
Niels Lohmann 33b7b30d06 Merge branch 'json-view/23-zmij' into json-view/08-view-builder
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-07 20:26:42 +02:00
Niels Lohmann cb3c0177ed Merge branch 'json-view/02b-float-parser' into json-view/23-zmij
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-07 20:26:39 +02:00
Niels Lohmann 39d34f30ba Merge branch 'develop' into json-view/02b-float-parser
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-07 20:26:13 +02:00
Niels Lohmann 88ddacb84b Fix CI warnings in own float parser
- pow5_table.hpp: pow5_128_largest_power was unused in this branch's
  own code (GCC -Werror=unused-const-variable); tie it to the table
  size with a static_assert instead of removing it, since a later
  branch in the stack (json-view/23-zmij) uses it.
- number_parse.hpp: rename the local variable `copy` to `buffer` to
  satisfy cpplint's build/include_what_you_use check.
- unit-class_lexer.cpp: extend the NOLINT list on the seeded mt19937
  with bugprone-random-generator-seed, and parenthesize
  `8 * sizeof(Bits) - 1` for clang-tidy.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-07 20:26:12 +02:00
Niels LohmannandAfonso Januário a5f5d3059b Make std::hash<basic_json> consistent with operator== for numbers (#5772)
* Make std::hash<basic_json> consistent with operator== for numbers

operator== converts between number_integer, number_unsigned, and
number_float before comparing, so json(0), json(0U), and json(0.0)
all compare equal. hash() folded the specific value_t into the
result for each of the three numeric cases, giving each a distinct
hash and breaking the standard Hash requirement that a == b implies
hash(a) == hash(b). A std::unordered_set could therefore hold all
three as separate elements even though they compare equal.

hash() now treats all three numeric variants the same way: it
converts the value to number_float_t and combines it with a single
shared type tag, so any two numbers operator== considers equal hash
identically regardless of which internal type actually holds them.

Updated the accompanying test to check this consistency directly
(including via an actual unordered_set) instead of asserting that 0,
0U, and 0.0 hash differently, since that assumption was the bug.
Also corrected the function's own doc comment and the std::hash API
docs, which described the old behavior as intended.

Fixes #5400

Signed-off-by: Afonso Januário <afonso-januario@hotmail.com>
Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Remove now-unused number_integer_t/number_unsigned_t typedefs in hash()

Merging the three numeric branches into one that only reads
number_float_t left these two aliases unused, which several CI
configurations treat as a build error under -Wunused-local-typedefs.

Signed-off-by: Afonso Januário <afonso-januario@hotmail.com>
Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Mark the unordered_set in the hash regression test const

clang-tidy's misc-const-correctness check flagged it: the set is
never mutated after construction, only read via size().

Signed-off-by: Afonso Januário <afonso-januario@hotmail.com>
Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Normalize -0.0 in number hashes and test range ends

operator== compares numbers exactly since #5459, so equal numbers
share one value and convert to the same number_float_t. Update the
comment accordingly, map -0.0 to 0.0 before hashing (std::hash need
not do that), and test -0.0 and the ends of the integer ranges. Show
hash(0.0) in the docs example and note the change in the version
history.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Clarify hash documentation after review

- Say "may hash differently" for null, false, and numbers, since a
  collision across types is possible.
- Name the storage types (signed integer, unsigned integer,
  floating-point number) instead of example literals.
- Explain that the hash survives converting an integer to
  number_float_t but not the lossy conversion back, and that unequal
  numbers may share a hash.
- State that the example hash values are illustrative only and vary by
  platform, compiler, compiler version, and library version.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

---------

Signed-off-by: Afonso Januário <afonso-januario@hotmail.com>
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
Co-authored-by: Afonso Januário <afonso-januario@hotmail.com>
2026-10-07 19:18:51 +02:00
43fe8928e1 Stop binary writers overflowing the stack on deep values (#5781)
* Stop binary writers overflowing the stack on deep values

to_cbor, to_msgpack, and to_ubjson recurse once per nesting level.
The parser is iterative, so a value the library accepts can crash on
the way back out.

Keep the existing recursive path for the first 128 levels and finish
anything deeper on a heap stack. Output is unchanged. BSON is left
alone because its extra size walk is a separate change.

Rebased onto the value-type output sink. The heap frames now initialize
every member, which is what -Weffc++ was rejecting.

See #5392.

Signed-off-by: ayush-singh-0601 <singhayush062006@gmail.com>
(cherry picked from commit cf65ac438f)
Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Redesign the iterative binary writers around a shared recursion depth limit

Address the open review on the non-recursive CBOR/MessagePack/UBJSON/BJData
writers (#5518):

- Delete the CBOR array/object prefix helpers; both the recursive and
  iterative paths call write_cbor_head(), which already existed on develop.
- MessagePack: share one write_msgpack_array_prefix()/write_msgpack_object_prefix()
  helper per container kind between the recursive and iterative paths, both
  going through to_msgpack_length() so an over-long container throws
  out_of_range.412 identically either way.
- Reuse detail::recursion_depth_limit() instead of a separate constant, the
  same bound serializer::dump() and write_bson_document() already use.
- Redesign the frames after bson_frame/dump_frame: only a container with
  elements is ever pushed, its header is written at the point it is pushed,
  and the iterator is set in the frame's constructor instead of a
  default-then-assign two-step with a since-removed "started" flag. The
  UBJSON frame keeps only the value pointer, the per-element prefix_required
  flag, and the iterator; write_closer and is_object are no longer stored,
  since the former is always !use_count (use_count is constant for the whole
  document) and the latter follows from value->is_object().
- Factor the BJData ND-array shape check into is_bjdata_ndarray(), used by
  both the recursive object case and the iterative pushing logic.
- Give the frame classes the GCC -Weffc++ treatment already used for
  diff_frame: a noexcept converting constructor plus the five special members
  defaulted with no explicit noexcept.
- Fix two @ref self-references in write_cbor/write_msgpack/write_ubjson's own
  doc comments to point at the public to_cbor/to_msgpack/to_ubjson/to_bjdata
  API instead.
- The iterative object-key write for CBOR/MessagePack now runs the same
  strict-mode check_utf8() against the parent object as diagnostics context
  that the recursive path already ran, so the two paths raise identical
  diagnostics across the switch-over.
- Rewrite the tests: round trips instead of a bare size check, byte-exact
  comparisons against the recursive output at depths around the bound, a
  deep object and a BJData ND-array past the bound, a deep discarded value
  (type_error.321), and the OSS-Fuzz 566583014 CBOR/MessagePack regression.

BSON is unaffected by this change; it already walks its documents
iteratively and is covered separately by #5553.

Co-authored-by: ayush-singh-0601 <179524189+ayush-singh-0601@users.noreply.github.com>
Signed-off-by: Niels Lohmann <mail@nlohmann.me>

---------

Signed-off-by: ayush-singh-0601 <singhayush062006@gmail.com>
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
Co-authored-by: ayush-singh-0601 <singhayush062006@gmail.com>
Co-authored-by: ayush-singh-0601 <179524189+ayush-singh-0601@users.noreply.github.com>
2026-10-07 19:18:20 +02:00
Niels Lohmann 3c465beb61 Add tests for error_handler_t::keep in dump() (#4555)
Squashed onto develop from:
- Add error_handler_t::keep to copy invalid UTF-8 bytes unchanged
- Mention error_handler_t::keep in the README

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-07 19:17:57 +02:00
Niels LohmannandMihnea Magheru e752688b52 Add a natvis fallback visualizer for detail::json_default_base (#5588)
* Add a natvis fallback visualizer for detail::json_default_base

Squashed onto develop from:
- Add a type in the natvis template for detail::json_default_base
- Document the json_default_base natvis fallback and regenerate natvis
- Match json_default_base in both its current and 3.12.0 namespace

Co-authored-by: Mihnea Magheru <sakuntalle@yahoo.com>
Signed-off-by: Mihnea Magheru <sakuntalle@yahoo.com>
Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Take the natvis template from the PR in the amalgamation check

The check ran generate_natvis.py from a develop checkout, which loads
nlohmann_json.natvis.j2 from its own directory. A PR that changes the
template was therefore checked against develop's template and always
failed. Copy the PR's template next to the develop script before
running it.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

---------

Signed-off-by: Mihnea Magheru <sakuntalle@yahoo.com>
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
Co-authored-by: Mihnea Magheru <sakuntalle@yahoo.com>
2026-10-07 19:17:41 +02:00
Niels Lohmann 069ace74af Round-trip BJData ND-array annotations exactly (single precision, key order) (#5707)
Squashed onto develop from:
- Round-trip BJData ND-array annotations exactly (single precision, key order)

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-07 19:17:18 +02:00
Niels Lohmann 73ceb71c95 Add images of json_documents: save() and load()
An image is a document stored so that loading it needs no
parsing: save() writes the node index, the text and the decoded
strings; the static load() reads an image written by save().

load() takes a pointer and size, a borrowed vector, or an owned
rvalue vector; the nodes are copied so they are aligned and can
be edited, while the text and decoded strings stay in the image.

image_check controls how much load() trusts the input: full
checks structure, bounds, strings and numbers, the parser's own
guarantees; bounds checks structure and bounds only; none skips
all checks, for images from a trusted source.

Layout is little-endian only ("NJVI" header, nodes, text, decoded
strings), following the idea of zero-copy formats such as
FlatBuffers and YaFF; the check follows FlatBuffers' Verifier.

New errors: parse_error.116 for a malformed image or a failed
check, type_error.320 for a discarded document or a big-endian
target.

A dedicated fuzzer and 6,000 seeded corruptions, checked under
ASan/UBSan, found and fixed two gaps: unchecked reserved header
fields, and unbounded null/boolean offsets that could make
dump() throw std::length_error.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-07 16:42:51 +02:00
Niels Lohmann c6ee5a64be Add editable json_documents: set, push_back, insert, and erase
basic_json_document gets a second template parameter, Editable
(false by default), plus the aliases json_editable_document,
json_editable_view, ordered_json_editable_document and
ordered_json_editable_view.

Editable documents can change values and structure without
rewriting the source text: set()/push_back() on values, keys,
array indices and JSON pointers; insert() before an array
element; erase() of an object key, array index or JSON pointer.

New values and element sequences go into edit storage that the
document owns and never moves, so views keep referring to their
value across edits and a parsed node never moves. Read-only
documents walk the plain node array and are unaffected.

Strings are checked for UTF-8 on entry, so dump() of an editable
document never throws type_error.316. Binary values cannot be
stored (type_error.319).

A seeded differential test applies random edits to an editable
document and to the equivalent ordered_json and compares both
after every step.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-07 16:42:38 +02:00
Niels Lohmann 8daec2b596 Scan json_view strings with SIMD and index large objects
Speed up json_view's parser with SIMD scanning and a hash table
for large objects.

Long runs of string bytes are scanned 16 bytes at a time with NEON
(AArch64, GCC and Clang) and SSE2 (x86-64), both baseline
instruction sets. Keys keep 16 table checks before the vector
loop, because their lengths repeat from record to record; string
values get 8, because their lengths vary more. Non-ASCII text is
validated 16 bytes at a time with simdjson's "lookup4" check
(Keiser and Lemire, 2021), with NEON on AArch64 and, on x86-64,
with SSSE3. SSSE3 is not part of baseline x86-64, so the check is
compiled for SSSE3 with a function attribute and used only where
CPUID reports it, which all x86-64 CPUs since about 2011 do; the
answer is cached in a statically initialized atomic, so there is
no guard of a local static and no global constructor. The same
input is accepted either way. JSON_VIEW_NO_SIMD selects the
portable code.

On x86-64, string runs are now checked vector-first: one SSE2
compare from the first byte finds the end of most keys and short
values, instead of a branch per byte for the first 8-16 bytes.
AArch64 keeps the byte-wise steps, where a NEON mask costs more and
the branches predict well. Entering an object or array no longer
stalls: open() stores the parent's frame field by field instead of
building it on the stack and reading it back with wider loads,
which waited for the narrower stores to retire.

Objects with 128 members or more get an open-addressing hash table
built when the object closes, so operator[], at(), find(),
contains(), count(), value(), and JSON pointers take constant time
on average in such objects; of duplicate keys, the first is kept,
as for the linear search. The idea comes from Boost.JSON.

simdjson is credited in simd.hpp's SPDX block, the README, and
license.md.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-07 16:42:32 +02:00
Niels Lohmann da1ca7f9d7 Add dump() and comparisons to json_view
Add basic_json_view::dump() and the comparison operators, and read
floats from the parser's digit layout instead of rescanning the
token.

dump(indent, indent_char, ensure_ascii, number_format) writes a
value the way ordered_json::parse(text).dump() writes it for the
same arguments: members in document order, all of them should a
key occur more than once; strings escaped by the same rules, using
the library's scanning kernels; floats written with the library's
to_chars conversion, so the output equals basic_json's byte for
byte; integers copied from the source, where they are already
canonical, except -0, which parse() reads as 0. There is no
error_handler argument, because the view only holds valid UTF-8.
number_format::source copies numbers exactly as they appear in the
source (e.g. "1.50", "1E2", "-0"), which basic_json cannot provide.
operator<< takes the indentation from the stream width, as for
basic_json. The writer walks iteratively, so nesting depth is
limited by memory only.

operator== and operator!= compare two views, or a view and a
basic_json value in either order, by the rules basic_json's
operator== uses: numbers compare by value across their types,
objects compare by their members with duplicate keys resolved as
parse() resolves them, member order matters only where the object
type keeps one, and discarded views compare as discarded basic_json
values do, including under JSON_USE_LEGACY_DISCARDED_VALUE_COMPARISON.
Nothing is materialized except single scalars.

While parsing, the view now records where the integer digits, the
fraction digits, and the exponent of a float token are, so floats
and doubles with at most 19 digits are read from that layout with
the library's decimal_to_float() instead of rescanning the token.
Both round correctly, so the values are those of parse(). get<double>(),
materialize(), dump(), and the comparisons all use it.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-07 16:42:29 +02:00
Niels Lohmann 77acd4563c Add element access, iteration, values, and JSON pointers to json_view
Give basic_json_view the read-only access functions of basic_json:
operator[] and at() with keys and indices, front()/back(), find(),
contains(), count(), begin()/end() and cbegin()/cend(), items()
with structured bindings from C++17 on, and type_name().

Exceptions have the ids and messages of the const functions of
basic_json. Where basic_json has undefined behavior the view
answers safely: operator[] with a missing key or an out-of-range
index returns a discarded view, and front()/back() of an empty
container throw invalid_iterator.214. Objects are iterated in
document order, and all members are visited; duplicate-key lookups
find the first member (as yyjson and simdjson do), while parse(),
materialize(), and the map conversions keep the last value, as
parse() does. Keys of up to 16 bytes are compared with two
overlapping loads.

Add value conversions: get<T>()/get_to() for arithmetic types,
bool, nullptr_t, strings (std::basic_string copied,
string_view_t without a copy), BasicJsonType, views, std::vector,
and maps with string keys; get_string() for the string without a
copy; number_token() for the number exactly as written in the
source; value() with keys and JSON pointers; and operator[]/at()/
contains() with JSON pointers. Everything else, including types
with from_json(), goes through materialize() of that subtree.
get<T>() of arithmetic types is inlined down to the conversion, so
reading an integer needs no call.

detail::json_pointer_access exposes a pointer's reference tokens
to code outside basic_json.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-07 16:42:26 +02:00
Niels Lohmann 759dd2e1b1 Add json_document and json_view: node index, parser, and document
Add json_document and json_view, a read-only, zero-copy index of a
JSON text, as the first public slice of the zero-copy view (#5295).

A parse produces a flat array of 16-byte nodes in document order,
one per value and one per object key. Strings stay in the source
text; escaped strings are decoded into an arena. Integers are
converted while their digits are in the cache; floats keep only
their digit layout and are converted on read. Containers store the
size of their subtree, so a reader can step over one in constant
time. A document makes a handful of allocations, however many
values it has.

The parser accepts exactly what json::parse accepts, with every
combination of ignore_comments and ignore_trailing_commas, with and
without a trailing NUL, and under JSON_STRICT_NUL_HANDLING. It is
portable C++11 and does not depend on byte order.

basic_json_document adds parse, parse_copy, accept, read (reuses a
document's memory), root, is_discarded, source, owns_source,
node_count, memory_usage, and shrink_to_fit. basic_json_view adds
type, the is_* queries, operator bool, size, empty, materialize,
and source_offset. A parse error throws the same exception
basic_json::parse would throw for the same input, message and
position included.

detail::abi_config keeps JSON_STRICT_NUL_HANDLING and
JSON_USE_LEGACY_DISCARDED_VALUE_COMPARISON readable after json.hpp
undefines them, in the ABI namespace so they always match the
basic_json in use.

A NUL byte that ends a // comment is the end of the input, as in
parse() since #5696.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-07 16:42:22 +02:00
Niels Lohmann bfa4886f0f Write doubles with the shortest digits (Żmij), digits in registers
Write doubles with the conversion of Zmij by Victor Zverovich (MIT),
ported to C++11 (detail/conversions/zmij.hpp). It finds the
shortest decimal that reads back as the same double, and the
closest one if there are several. Grisu2, used until now, is fast
but not always shortest: it sometimes writes a 17th digit where 16
suffice, or a last digit that is not the closest. The layout is
unchanged (1.5, 100.0, 1e+100, -0.0); float keeps Grisu2.

Digits are converted eight at a time with the BCD conversion of
Xiang JunBo, as in Zmij, and written with one byte swap per eight
digits and fixed-size moves instead of per-digit loops. Leading and
trailing zeros are counted from those bytes. to_chars() uses a
local buffer when the caller's is shorter than the 41 bytes this
may write. The powers of ten come from the number-parsing table,
adjusted where it holds values rounded up, and extended with Zmij's
compressed tables beyond 10^308.

write_shortest() converts its 16 digits in one vector register
(SSE2 on x86-64, NEON on 64-bit Arm, both baseline) and inserts the
decimal point inside the register, avoiding a store-forwarding
stall that cost about 25% of the time to write a double. dump()
writes floats and integers straight into the serializer's write
buffer instead of copying them from a member buffer, and small
integers eight digits at a time. read_eight_bytes() and
parse_eight_digits() are marked always-inline, which GCC had been
calling out of line in the number-parsing loops.

Of one million random doubles, about 0.14% are now written with
different digits, always to a value that still reads back as the
same double.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-07 16:41:47 +02:00
Niels Lohmann 68d61b6aef Speed up the lexer: own float parser, string scan, and \u table
Give the library its own correctly rounded float converter for
binary32 and binary64 (IEEE 754), and speed up the lexer's string
and escape scanning.

The converter splits a number token into sign, significand, and
decimal exponent, then tries Clinger's fast path, then a templated
Eisel-Lemire step, and falls back to an exact big-integer digit
comparison for tokens with more than 19 significant digits whose two
candidate values round differently. This replaces std::from_chars
and strtod/strtof for both formats, so parsed values no longer
depend on the C/C++ library or the current locale. The strtold
fallback kept for other long double formats (x87, binary128) now
also copies a multi-byte decimal point correctly, fixing #5660.
eisel_lemire() and decimal_to_float() are always inlined so callers
keep the whole conversion in their hot loop.

The string-scanning kernels in string_scan.hpp find a stop byte with
the trailing-zero count of the SWAR mask instead of a byte loop, and
scalar_string_bulk_run() validates a run of multi-byte UTF-8
sequences one after another instead of re-searching after each one.

get_codepoint() decodes a contiguous \uXXXX escape with one table
lookup per byte instead of four range-checked get() calls; the
streaming path and all error positions are unchanged.

Adds 508 generated hard float-parsing cases with expected binary32
and binary64 bits, and kernel-comparison tests for the string scans
and the escape table against byte-by-byte references.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-07 16:41:43 +02:00
Niels Lohmann 367336c83d Fix CI on develop after #5585 (#5779)
* Fix CI on develop after #5585

- test-diagnostics-optimized: -O3 makes GCC's -Winline and
  -Wsuggest-attribute=pure/const warnings fire with the ci_test_gcc flag
  set; turn them off for this test.
- test-diagnostics-optimized: suppress Clang's -Wexit-time-destructors for
  the static table in to_json.
- Infer: raise pulse-max-disjuncts from 20 to 40. With the default,
  Pulse loses the stored type in basic_json::replace_value() and reports
  false null dereferences of get_ptr() results in unit-pointer_access.cpp.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Ignore Infer's false USE_AFTER_DELETE in ordered_map::erase

Infer's std::string model keeps the buffer of a moved-from string, so the
destroy-and-reconstruct loop in erase(first, last) looks like it destroys a
buffer twice.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Mark throw_on_discarded()'s parameters as used without exceptions

With JSON_NOEXCEPTION, JSON_THROW expands to std::abort(), so Clang's
-Wunused-parameter breaks test-disabled_exceptions (since #5761).

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Skip the span_input_adapter sax_parse checks with deleted deprecated functions

The #5676 regression test (#5740) calls the deprecated
sax_parse(span_input_adapter&&, ...), which JSON_DELETE_DEPRECATED_FUNCTIONS
deletes, so ci_test_delete_deprecated_functions failed to build.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Fall back to the first entry in test-diagnostics-optimized's to_json

clang-tidy (clang-analyzer-security.ArrayBound) flagged it->second for a
value not in the table. Use the same fallback as
NLOHMANN_JSON_SERIALIZE_ENUM; the test still fails with -Werror=array-bounds
on the headers from before #5585.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Fix clang-tidy findings in tests from #5762 and #5774

- unit-regression2.cpp (#5762): const/auto for the destroy() test values;
  NOLINT the intended copy in check_destroy_edge_case().
- unit-serialization.cpp (#5774): build the expected strings with += instead
  of chained operator+ (performance-inefficient-string-concatenation).

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

---------

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-07 16:37:19 +02:00
Niels Lohmann 30e542e52a Declare the namespace-scope constants in to_chars.hpp inline (#5776)
MSVC warns with C5260 that kAlpha and kGamma have internal linkage when
the header is used as a header unit or through a module. JSON_INLINE_VARIABLE
makes them inline variables from C++17 on.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-07 09:03:18 +02:00
Niels Lohmann 24dd7c63f0 Re-amalgamate after #5740 (#5777)
#5740 changed include/nlohmann/json.hpp without regenerating
single_include/nlohmann/json.hpp.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-07 09:03:17 +02:00
Niels Lohmann e6f32bd28a Stricter fuzzer checks and boundary-value tests for buffers (#5774)
* Check in the fuzzers that parsing without exceptions agrees

Each fuzzer driver now also parses its input with allow_exceptions =
false. That call must never throw a parse_error, must return a discarded
value where parsing with exceptions fails, and must return the same value
where it succeeds. Values are compared by their dump(), because NaN is
not equal to itself.

A plain !is_discarded() assertion, as suggested in #3642, would never
fail: the drivers parse with exceptions, so a result can never be
discarded.

tests/fuzzing.md describes the checks and notes that OSS-Fuzz and
CIFuzz already run LeakSanitizer, because their default address
sanitizer includes it.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Use JSON_HAS_RANGE_VIEW_CONVERSION in the range view regression tests

#5728 combined the JSON_HAS_RANGES and MinGW conditions into
JSON_HAS_RANGE_VIEW_CONVERSION, but three test guards still spelled
them out.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Test the serializer's buffers at their boundaries

The dump() indent overflow survived full line coverage because the tests
grew its buffer by only one step. This adds tests that land exactly on,
and one past, the limits of the other two serializer buffers:

- write_buffer (1024 bytes): strings of 1023, 1024 and 1025 bytes at the
  top level, and of 1022 and 1023 bytes inside an array, so that both
  guards in put_string() are hit at their boundary. Each is checked for
  dump() and for stream output.
- string_buffer (512 bytes, flushed when fewer than 13 bytes remain):
  runs of two-byte escapes, and a surrogate pair written with 14 bytes of
  room, right after a flush, and one escape later.
- The 8-byte bulk scan from the serializer side: 0 to 17 plain bytes
  followed by a quote, a control character, or a non-ASCII character.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Test the chunked string and binary reads of all binary formats

The binary readers read strings and binary values in chunks of 4096
bytes. Only CBOR tested lengths around that size. MessagePack, UBJSON,
BJData and BSON now round-trip lengths 0, 1, 4095, 4096, 4097, 8192 and
100000 from vector and pointer input, and must report a truncated
payload as a parse error.

UBJSON reads binary values as arrays of numbers, so it is tested with
strings only. BJData binary values reach the chunked read only in
Draft 3. BON8 decodes strings byte by byte and does not use this path.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

---------

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-07 08:50:12 +02:00
Niels Lohmann e4e7d657ef Document the API stability guarantee in the roadmap (#5775)
* Document what is not covered by the API stability guarantee

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Move the API stability guarantee to the roadmap

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Note that exceptions to the API stability rules are documented in the release notes

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

---------

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-07 08:49:51 +02:00
Niels Lohmann ef570827e3 Point the README's fuzzing badge to the current OSS-Fuzz tracker (#5773)
OSS-Fuzz moved its issues from bugs.chromium.org to issues.oss-fuzz.com.
The old link now redirects to the new tracker but drops the project
filter, so it showed every project's issues.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-07 07:39:44 +02:00
Niels Lohmann 1c754cfe31 Copy a pair-shaped array value under JSON_BRACE_INIT_COPY_SEMANTICS (#5701)
With JSON_BRACE_INIT_COPY_SEMANTICS enabled, single-element brace
initialization from a JSON value decided whether to copy the value or
build an object by inspecting the value's runtime shape: a two-element
array whose first element is a string, such as ["key", 42], was turned
into an object instead of being copied. This made the behavior depend
on the element's content, and it did not distinguish an existing value
of this shape from a nested braced pair written in the source, such as
the inner {"key", "value"} of {{"key", "value"}}.

json_ref now records whether it was constructed from a braced list
(true only for the std::initializer_list<json_ref> constructor used
for nested braced lists) or from a value. The initializer-list
constructor uses this to copy or move a single non-braced-list element
before deciding whether the list describes an object, so a JSON value
is always copied regardless of its shape, while a braced pair written
in the source still creates an object.

Fixes #5662.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-07 07:39:05 +02:00
Niels LohmannandJoseph.Demarest ff6f3d7d4a Reject nested indefinite-length CBOR string chunks (#5766)
* fix(cbor): reject nested indefinite string chunks

Signed-off-by: Joseph.Demarest <joseph@demarest.dev>
Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Address review comments on nested indefinite-length CBOR strings

Rename is_chunk to inside_indefinite, update the stale test section
names, and use lowercase comments like the surrounding code.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

---------

Signed-off-by: Joseph.Demarest <joseph@demarest.dev>
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
Co-authored-by: Joseph.Demarest <joseph@demarest.dev>
2026-10-07 07:38:52 +02:00
Mohd Quamar TyagiandNiels Lohmann 675e519966 Allow SAX parsing of tagged CBOR (#5740)
* Allow SAX parsing of tagged CBOR

Signed-off-by: Tyagiquamar <mohdquamartyagi@gmail.com>

* Consolidate sax_parse overloads with default tag_handler parameter

Signed-off-by: Tyagiquamar <mohdquamartyagi@gmail.com>

* Add version history entry for tag_handler in sax_parse documentation

---------

Signed-off-by: Tyagiquamar <mohdquamartyagi@gmail.com>
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
Co-authored-by: Niels Lohmann <mail@nlohmann.me>
2026-10-07 07:38:24 +02:00
Niels Lohmann 21a69230bd Create a value before giving it its type (#5585)
* Create a value before giving it its type

Squashed onto develop from:
- Create a value before giving it its type
- Skip the failed-allocation test when exceptions are disabled
- Keep the created pointer rather than an uninitialized json_value
- Skip the vector<bool> failed-allocation check for VS 2015 with iterator debugging
- Test the remaining to_json overloads with a failing allocation
- Skip the to_json allocation-failure section on VS 2015 Debug
- Fix false GCC -Warray-bounds error with JSON_DIAGNOSTICS at -O3 (#5744)

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Store the new value with a helper in all to_json constructors

Every external_constructor<>::construct now creates the new value first and
hands it to basic_json::replace_value(), which destroys the old value, stores
the new one before setting its type (as elsewhere in this PR), sets the
parents, and checks the invariant.

The std::vector<bool> and std::valarray overloads use array_t's range
constructor, which the other array overloads already rely on. Range views
keep their loop, as begin() and end() of a view may have different types.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

---------

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-06 22:59:34 +02:00
Niels Lohmannandelix3r 0c2329d0e2 Reduce test suite runtime and run the Unicode tests everywhere (#5605)
Squashed onto develop from:
- Cut Unicode ill-formed byte sweeps to one representative prefix
- Pin unrelated bytes in the remaining ill-formed UTF-8 sweeps
- Speed up unit-unicode1
- Run the cheap binary format size tests unconditionally
- Compile unit-msgpack.cpp only once
- Check the JSON Pointer roundtrip for every code point again
- Cover every byte class in the ill-formed UTF-8 sweeps
- Merge the Unicode tests into unit-unicode.cpp
- Stop excluding the Unicode tests in CI

Signed-off-by: elix3r <157088510+22elix3r@users.noreply.github.com>
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
Co-authored-by: elix3r <157088510+22elix3r@users.noreply.github.com>
2026-10-06 22:53:03 +02:00