Commit Graph
950 Commits
Author SHA1 Message Date
Niels Lohmann 414b4e6d27 Merge develop into fix/bjdata-count-size-max
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-11-02 18:27:15 +01:00
Niels Lohmann b18b6fc7e6 Build the parser's syntax error prefix with one concat() (#6013)
Since #6004 made the "while parsing" part unconditional, the three appends
at the start of exception_message() are one fixed string around the
context. Review follow-up to #6004.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-11-02 18:27:08 +01:00
Niels Lohmann 6d5581c4e8 CBOR/MessagePack readers: leave one-element arrays to the general path (#6008)
enter_cbor_array and enter_msgpack_array called the out-of-line scalar
run for every non-empty array. When the array's element is an object or
an array, as on every level of [[...]] or the single ring of a GeoJSON
polygon, the call reads nothing; it made 1,000 arrays nested in each
other cost 4 % more instructions (GCC 13) and up to 8 % more time (Apple
clang) than without the run. #5975 had fixed that with an inline
pre-check, which was later dropped after measuring canada only.

The run is now entered only for arrays of two or more elements: the same
comparison as before, so no other row changes. Arrays of one scalar,
which the run read faster, now take the general path; they are rare in
documents (one in citm_catalog, none in twitter or canada). The new
benchmark FromBinaryShape/singles measures them, next to
FromBinaryShape/nested.

Instructions per repetition, new/old, GCC 13 callgrind: nested arrays
0.973 (CBOR) and 0.971 (MessagePack), arrays of one scalar 1.037 and
1.021, every other row within 0.15 %.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-11-02 18:25:44 +01:00
Niels LohmannandClaude 590b622d48 parse(): propagate std::bad_alloc instead of crashing on a half-constructed member (#5991)
* Create the DOM parser's member value before placing it (#5985)

json_sax_dom_parser::set_member() constructed the new value in place over
the null member. basic_json(value_t) sets the type before the json_value
allocates, so a std::bad_alloc left a member typed object/array with a
null pointer, and the destructor crashed instead of propagating the
exception. Construct the value first and move it over the member (the
move constructor is noexcept).

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

* Fix CI for the parse() bad_alloc sweep test (#5985)

- sweep_allocator: provide max_size(), construct() and destroy(), which
  GCC 4.8's std::map calls on the allocator directly.
- Declare the non-throwing test lambdas noexcept (-Werror=noexcept on
  recent GCC).
- Give the sax_parse lambda an explicit return type; Clang 3.4 crashes on
  the deduced one in C++11 mode.
- Skip the parser callback sweep with iterator debugging (MSVC debug
  builds, clang-cl), where containers allocate debug proxies inside
  noexcept move constructors and terminate instead of throwing, as in the
  other allocator tests.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01N5NasAgbDGG28MqXjQvLqp
Signed-off-by: Claude <noreply@anthropic.com>

* Construct a scalar member in place; only a throwing value goes through a temporary

Creating the value first and moving it over the member is needed only when
creating it can throw (a string, a binary value or a container). A scalar
or null is again constructed in place, without the extra move and destroy
per member (and, with JSON_DIAGNOSTICS, without the extra set_parents()).

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

* Spell the nothrow trait without && and fix the construct_member comments

The dispatch in set_member tests std::is_nothrow_constructible, not
whether the value is a scalar. Say so in the comments, and drop the &&
from the trait argument (equivalent for a forwarding reference) so that
astyle no longer inserts spaces around the template brackets.

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

* Say "for example" in the construct_member comments

The overloads are selected by std::is_nothrow_constructible, not by the
kind of value: a custom type that cannot throw takes the first one.

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

---------

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
Signed-off-by: Claude <noreply@anthropic.com>
Co-authored-by: Claude <noreply@anthropic.com>
2026-11-02 18:25:30 +01:00
Niels Lohmann da6d21ae24 MessagePack reader: reject an array/map 32 length equal to SIZE_MAX
On a platform with a 32-bit std::size_t, an array 32 or map 32 length of
0xFFFFFFFF equals unknown_size(), so start_array()/start_object() were
told the size was unknown and skipped the max_size() check. Route both
through the CBOR length check, renamed get_container_size(), which
already rejects that value.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-11-02 18:25:06 +01:00
Niels Lohmann 100f676b3e Restore the two commits of #6005 that the stack merge dropped (fixes the build of develop) (#6012)
* basic_json, iterators, serializer: remove checks that invariants make dead

Branch coverage of the test suite and of 24k mutated inputs showed
these conditions as never taken; each is implied by the code around it:

- copy_object_level(): `src_it != src_object.cend()`; dst was built from
  exactly src_object.size() unique keys and src_it advances at most once
  per member
- the general comparison operators (equal_general, less_general,
  three_way_general): the five same-type scalar cases, which the inline
  fast path of every operator handles before calling them (now an
  assert); and the NaN half of compares_unordered() in the mixed-type
  branch, reached only after all six number pairs returned, where only
  a discarded operand is unordered
- serializer, ensure_ascii: the reset of `bytes` under error_handler_t::keep
  and the surrogate-pair escape in the UTF8_ACCEPT case; every
  well-formed multi-byte character is escaped by write_u_escapes() before
  decode() sees it, so decode() only ever accepts DEL here, a single byte
  of which nothing was buffered (now asserts)
- iter_impl(pointer): the if/else chain assigned value-initialized
  iterators to the value-initialized m_it

No change in behaviour: a build that aborts on each removed side passes
the test suite, the fuzz corpora and 23.2M dumps of all 1-, 2- and
boundary 4-byte strings in both ensure_ascii modes.

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

* iter_impl: keep the type-dependent initialization in the constructor

The check is not needed for correctness (m_it is value-initialized), but
without it GCC 13 generates slower iteration loops: a recursive walk over
a parsed document takes 0.5-2.7 % longer (callgrind: +1.9 % instructions
on twitter.json, +0.95 % on canada.json). Clang generates identical code
either way. See the measurements in #6005.

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

---------

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-11-02 18:23:44 +01:00
Niels Lohmann 3354436ec4 json_view: remove checks that invariants make dead (#6006)
Branch coverage of the test suite and of 24k mutated inputs showed
these conditions as never taken; each is implied by the code around it:

- view_serializer::write_codepoint<EnsureAscii>(): the only caller
  passes the byte a run of plain output stopped at (a quote, a
  backslash or a control character), so the function is now
  write_escaped(), which writes that byte's escape sequence
- load_image(): `owned_image.empty() || image != owned_image.data()`;
  both callers hand in a fresh document_data, and for load(vector&&)
  the image is owned_image itself
- set_moved(): reserve_moved(); all three callers reserved first or
  have the moved flag set (the documented precondition)
- view_side::string() and json_side::string() in equal(): only used
  after both sides were found to be strings, so they read the string
  directly (and are noexcept)
- number<false>(): the '1'..'9' test after a sign-less dispatch, which
  only happens for a digit
- value_range(): the pre-loop `is_new || off >= size` test, which the
  loop's first pass repeats on the same node

No change in behaviour: a build that aborts on each removed side passes
the test suite and the fuzz corpora.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-11-02 17:54:40 +01:00
Niels Lohmann 5c4f585ac2 Lexer, parser, stream adapter, SAX: remove checks that invariants make dead (#6004)
Branch coverage of the test suite and of 24k mutated inputs showed
these conditions as never taken; each is implied by the code around it:

- lexer: `next_unget` in get_codepoint_bulk() and scan_literal_bulk().
  unget() is only called at the end of scan_number(), in scan_comment()
  and in skip_bom(); every token scan starts with a plain get() in
  skip_whitespace() that consumes a pending unget, and nothing between
  that get() and the bulk helpers ungets (now asserts, as in
  get_after_string_run())
- lexer: `number_type == value_integer` in convert_integer(): both
  callers exclude value_float and the type has three values
- parser: `!context.empty()` in exception_message(): all callers pass a
  literal
- input_stream_adapter: `refill` in get_character_slow(): the function
  is only called after get_character() found the get area exhausted,
  and the variable recomputed that comparison
- json_sax_dom_callback_parser: `ref_stack.back()` in key() (the null
  case returned a few lines earlier, and the callback in between cannot
  reach ref_stack), `is_structured()` in end_object() (non-null entries
  are only pushed for objects and arrays), `!key_stack.empty()` in
  current_key() (a kept object pushed its key before any value)

No change in behaviour: a build that aborts on each removed side passes
the test suite, the fuzz corpora and 40k random documents through every
input adapter in four macro configurations.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-11-02 17:54:39 +01:00
Niels LohmannandClaude Opus 5.5 1d69ef9ab4 Raise line coverage to 99.9 %: fix the measurement, remove unreachable code, add tests (#5997)
* CI: measure line coverage without lcov's unexecuted-block adjustment

Drop geninfo_unexecuted_blocks=1 from the lcov capture of ci_test_coverage:
it reset every line of an inlined or templated function to 0 as soon as one
copy had an unexecuted block, which understated the line coverage by about
three points.

Add -fvar-tracking-assignments to both coverage builds. At -O0, GCC inlines
always_inline functions before it places the coverage counters, so the call
sites of such helpers (put_literal() and others) got no line record and
showed as 0 in an -O3 translation unit that never reaches them. With the
flag, the call sites carry counts in every translation unit. The generated
code is identical.

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

* Remove unreachable code found by the coverage analysis

Remove code that no input can reach, and mark the lines that cannot be
covered with LCOV_EXCL_LINE:

- BJData writer: the dry_run parameter of the ND-array element writers was
  always true; replace them by range checks.
- BON8 writer: call throw_integer_out_of_range() directly instead of
  write_bon8_value() for values that always throw.
- binary_writer: integer_bits() is only called for integers of up to 64 bits.
- serializer, view serializer, lexer: replace guards that the callers make
  unreachable by assertions or by the simpler code (surrogate pairs under
  ensure_ascii, next_unget, '-' at the end of the buffer).
- json_view: drop unreachable branches in scalar(), set(), check_utf8_scan(),
  append_input_impl() and unescape().
- Mark exception-cleanup braces, 2 GiB limits, big-endian and 32-bit code, and
  fall-through case labels with LCOV_EXCL_LINE.

No behavior changes for any input that reaches these functions.

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

* Tests: cover the remaining lines of the library headers

Add tests for the lines of include/nlohmann that were not covered: the
binary readers and writers, the lexer and locale paths, the json_view
modules, the custom number, key and array types, json_pointer, json_patch,
diff and the iterators.

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

* Fix test failures in the coverage tests

- unit-custom-object-key-type: remove the unused make_strict_key(strict_key)
  overload, the unused range constructor and default constructor, and guard
  data() with JSON_DIAGNOSTICS (unused-function/-member-function errors with
  GCC and clang -Weverything).
- unit-json_view_compare: move the two new sections to the new
  unit-json_view_compare_values.cpp, as the object file got too large for the
  MinGW assembler again, and use a std::map with std::greater instead of
  std::unordered_map, which does not accept the incomplete basic_json
  (clang 3.9, icpc).
- unit-json_view_dump: rename the variables that hid outer ones (MSVC C4456).
- unit-stream-bulk-scan: restore the real size of the oversized get area
  before the adapter is destroyed (JSON_PRECISE_STREAM_POSITION reads the
  character at the read position), and skip the test where the streambuf
  cannot hold a get area larger than an int (MSVC).
- unit-regression1: with JSON_NO_THREAD_LOCAL, copies are built member by
  member and keep correct timestamps, so check the corresponding outcome.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01N5NasAgbDGG28MqXjQvLqp
Signed-off-by: Claude <noreply@anthropic.com>

* Return std::size_t from the hash helper in the ordered_json test

MSVC (Win32) rejected the implicit conversion of the unsigned long long
product to the 32-bit std::size_t (C4244 as an error). Also note when
JSON_NO_THREAD_LOCAL is set in the regression test.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01N5NasAgbDGG28MqXjQvLqp
Signed-off-by: Claude <noreply@anthropic.com>

---------

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
Signed-off-by: Claude <noreply@anthropic.com>
Co-authored-by: Claude <noreply@anthropic.com>
2026-11-02 17:54:38 +01:00
Niels Lohmann ff0bdfdef3 Keep the byte range in exceptions about the root value (#5990)
* Keep the byte range in exceptions about the root value (#5987)

With JSON_DIAGNOSTICS and JSON_DIAGNOSTIC_POSITIONS both set, exception::diagnostics()
and the json_view diagnostics() returned early for a value without a path (the
root), dropping "(bytes a-b)". Build the "(path) " prefix only when there are
tokens and always append the byte range.

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

* Guard the null value of a value-initialized iterator; drop the unneeded found flag

With the root's byte range, diagnostics() reaches get_byte_positions() also
with JSON_DIAGNOSTICS when there is no value, as for a value-initialized
iterator (invalid_iterator.212). get_byte_positions() now returns no range
for a null value, the same change as #6003, so either can be merged first.

In the view, a value that value_path() does not find leaves no tokens, so the
found flag added nothing to the tokens.empty() test.

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

---------

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-11-02 17:50:40 +01:00
Niels LohmannandClaude Opus 5.5 bfe69c73c2 json_view: get<T>() of a boolean throws for the exact number types, as basic_json does (#5992)
* json_view: get<T>() of a boolean throws for number_integer_t, number_unsigned_t and number_float_t like basic_json (#5988)

basic_json::get<T>() of a boolean throws type_error.302 for exactly
number_integer_t, number_unsigned_t and number_float_t (dedicated from_json()
overloads) and gives 0/1 for every other arithmetic type. The view returned
0/1 for all of them, contradicting its documentation. The view now throws
the same exception (same message, with path/bytes decoration) for these three
types. basic_json is unchanged; its behavior is documented and pinned by a test.

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

* tests: skip throwing json_view bool get<T>() combinations without exceptions (#5988)

check_boolean_get_parity() called get<T>() for number_integer_t,
number_unsigned_t and number_float_t in its JSON_NOEXCEPTION branch, but a
boolean throws type_error.302 for exactly these types, so JSON_THROW aborted
test-json_view_cpp11/cpp17 in ci_test_noexceptions. Skip these combinations
there; the throwing checks stay in the exceptions-enabled build.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01N5NasAgbDGG28MqXjQvLqp
Signed-off-by: Claude <noreply@anthropic.com>

* Expect the byte range of the root in the json_view boolean get<T>() test

With JSON_DIAGNOSTIC_POSITIONS, the type_error.302 message starts with
"(bytes 0-4)"; build the expected text with json_view_test::message(),
as the other tests of the root value do.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01N5NasAgbDGG28MqXjQvLqp
Signed-off-by: Claude <noreply@anthropic.com>

---------

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
Signed-off-by: Claude <noreply@anthropic.com>
Co-authored-by: Claude <noreply@anthropic.com>
2026-11-02 17:48:43 +01:00
Niels LohmannandClaude Opus 5.5 bdc737db6d json_view: dump() without StringType::capacity() (#5999)
* json_view: dump() without StringType::capacity() (#5994)

output_buffer::grow() compared the output size with m_out.capacity(),
which the StringType requirements do not include, so dump() did not
compile with the tests' alt_string. Keep what was last reserved in the
buffer itself and use it as a lower bound of the capacity instead.

Add json_view tests with alt_string (read-only and editable documents,
dump with several growth steps, save/load), and document reserve(n) and
resize(n) as the StringType requirements of basic_json_view::dump.

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

* Use a raw string literal in the alt-string json_view test

clang-tidy (modernize-raw-string-literal) rejects the escaped literal.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01N5NasAgbDGG28MqXjQvLqp
Signed-off-by: Claude <noreply@anthropic.com>

---------

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
Signed-off-by: Claude <noreply@anthropic.com>
Co-authored-by: Claude <noreply@anthropic.com>
2026-11-02 17:48:16 +01:00
Niels LohmannandClaude Opus 5.5 03d408aafa JSON_DIAGNOSTIC_POSITIONS: comparing a value-initialized iterator throws instead of crashing (#6003)
* JSON_DIAGNOSTIC_POSITIONS: comparing a value-initialized iterator throws instead of crashing

With JSON_DIAGNOSTIC_POSITIONS, comparing a value-initialized iterator
(which has no container) with another iterator built the
invalid_iterator.212 message from the byte positions of the iterator's
value, which is a null pointer: UBSan reports "member call on null
pointer" in exception::get_byte_positions(), then the process crashes.
Every other configuration throws invalid_iterator.212.

get_byte_positions() now returns no positions for a null value, as the
JSON_DIAGNOSTICS path already does.

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

* Declare the value-initialized iterator in the test const

clang-tidy (misc-const-correctness) flags it, as it is only compared.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01N5NasAgbDGG28MqXjQvLqp
Signed-off-by: Claude <noreply@anthropic.com>

---------

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
Signed-off-by: Claude <noreply@anthropic.com>
Co-authored-by: Claude <noreply@anthropic.com>
2026-11-02 17:47:48 +01:00
Niels LohmannandClaude Opus 5.5 76dbe8f9c9 Fix the red CI on develop: Visual Studio 2017 build of the BSON writer, Valgrind timeouts (#6009)
* CI: give the Valgrind tests a timeout of one hour

Under Valgrind, test-json_view_builder_cpp11 and test-ordered_json_cpp11
took 1435 s and 1390 s on develop (ddc34f5), close to ctest's default
timeout of 1500 s. On the next run (b2674a4) the whole job was about 10 %
slower and both timed out, failing ci_test_valgrind on develop and on
every PR based on it.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01N5NasAgbDGG28MqXjQvLqp
Signed-off-by: Claude <noreply@anthropic.com>

* BSON writer: drop the SFINAE guard that Visual Studio 2017 cannot deduce

write_bson_document_single_pass() was a member template enabled by
is_detected<sink_written_t, SinkType>. MSVC 19.16 (Visual Studio 2017)
fails to deduce it through the class-scope alias template (C2672, C2783)
when it compiles to_bson() and to_bon8(), so every Visual Studio 2017
job on AppVeyor fails since #5979.

The guard is not needed: as a non-template member of the class template,
the function is only instantiated when called, and its only caller is
the write_bson_document() overload for sinks that have written(), which
already calls oa.written() and oa.rewind() itself.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01N5NasAgbDGG28MqXjQvLqp
Signed-off-by: Claude <noreply@anthropic.com>

---------

Signed-off-by: Claude <noreply@anthropic.com>
Co-authored-by: Claude <noreply@anthropic.com>
2026-11-02 17:47:21 +01:00
Niels Lohmann db73a6044f UBJSON/BJData reader: reject a container count equal to SIZE_MAX
The reader marks a container whose count is not known by npos, which
is SIZE_MAX. A count of exactly that value was stored unchanged and
then read as "no count", so the BJData input

    [ # M ff ff ff ff ff ff ff ff i 01 ]

parsed as [1] instead of throwing out_of_range.408 as a count of
2^64-2 does. Where size_t is 32 bits, the same holds for 'm' and 'L'
counts of 2^32-1, in UBJSON too.

The counts of 'm', 'M' and the signed types now go through
store_ubjson_count(), which rejects npos with "integer value overflow"
(the message a count beyond size_t already gets), as the CBOR reader
does in get_cbor_container_size(). An ND-array dimension of 2^64-1 gets
the same message now, where it was "excessive ndarray size caused
overflow" (the product check) on 64-bit platforms.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-11-02 07:01:16 +01:00
Niels Lohmann b2674a4a2f BSON reader: check array element names in place in strict mode (#5984) 2026-11-01 21:03:35 +01:00
Niels Lohmann ddc34f546a json_view: exceptions name the path and the bytes of the value (#5974)
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-11-01 17:25:26 +01:00
Niels Lohmann f022e3c59c Binary readers and writers: faster UTF-8 checks of strings (#5982)
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-11-01 17:23:27 +01:00
Niels Lohmann 9742edc294 BSON writer: write to_bson(j) in one pass, with sizes written afterwards (#5979)
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-11-01 17:23:12 +01:00
Niels Lohmann 517444b504 accept() checks strings without copying them (#5978)
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-11-01 17:22:58 +01:00
Niels Lohmann fb515ddc34 UBJSON/BJData readers: read optimized arrays of numbers in one loop (#5981)
* UBJSON/BJData readers: read optimized arrays of numbers in one loop

An array with a type marker for a fixed-size number ($U, $i, $I, $l, $L,
$d, $D, and BJData's $u, $m, $M), including the data of a BJData ndarray,
gives its elements no markers. When the input is contiguous, read the
elements that are in the input in one loop - load, byte swap for the
format's byte order, emit - instead of one trip through
parse_ubjson_internal and get_ubjson_value per element. Elements the
input ends before, other types, and non-contiguous inputs are read as
before.

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

* UBJSON/BJData tests: assign the parsed value instead of casting it to void

GCC reports -Werror=unused-result for static_cast<void>(json::from_ubjson(...))
and json::from_bjdata(...): a cast to void does not silence warn_unused_result
on GCC. Assign to a json, as the other tests do.

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

---------

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-11-01 17:22:33 +01:00
Niels Lohmann edf8d17601 MessagePack reader: read runs of scalar array elements in one loop (#5980)
* MessagePack reader: read runs of scalar array elements in one loop

As for CBOR: when an array opens and the input is contiguous, read the
integers, floats, booleans, and nils that follow in a tight loop instead
of going through parse_msgpack_internal and parse_msgpack_value for every
element. The loop stops at any other kind of value and when fewer than 9
bytes are left; those values are read by the general path as before.
Non-contiguous inputs are not affected.

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

* MessagePack reader: enter the scalar run only when a scalar follows

As for CBOR: enter_msgpack_array tests the first byte and the remaining length
inline and calls the out-of-line run only for a scalar, so arrays of maps or
strings no longer pay for a call that reads nothing; the run's loop condition
moves to the end (do-while).

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

* MessagePack reader: mark the initial accepted in the scalar run as a false-positive dead store

ci_infer reports DEAD_STORE for 'bool accepted = true;' in the MessagePack
scalar run, as in the CBOR one, because every case assigns accepted before it
is read.

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

* MessagePack tests: assign the parsed value instead of casting it to void

GCC (ci_test_gcc) reports -Werror=unused-result for
static_cast<void>(json::from_msgpack(...)): a cast to void does not silence
warn_unused_result on GCC. Assign to a json, as the other tests in the file do.

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

* MessagePack reader: drop the scalar pre-check before the run

enter_msgpack_array now calls the run directly, and parse_msgpack_scalar_run
tests the remaining count and length at the top of a while loop instead of
relying on msgpack_scalar_follows(); its own switch already leaves on any
value that is not a scalar.

Instructions per repetition, new/old: SAX canada 0.946 (clang) and 0.973
(GCC 13), DOM read canada 0.991 / 0.992; no row more than 0.3 % higher.

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

* MessagePack reader: say why the initial accepted in the scalar run stays

As for CBOR: Infer's DEAD_STORE report is right, not a false positive. The
initializer is kept for clang-tidy's cppcoreguidelines-init-variables.

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

* MessagePack reader: give the scalar run the bulk tag instead of a wrapper

As for CBOR: parse_msgpack_scalar_run takes the bulk-scan tag itself and is
the function kept out of line, so parse_msgpack_array_start goes.

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

* MessagePack reader: start the scalar run's accepted at false

As for CBOR: Infer ignores dead stores of 0, so the suppression goes.

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

* MessagePack reader: let the scalar run find its array itself

As for CBOR: parse_msgpack_scalar_run reads container_stack.back() in its
bulk version, so the caller no longer evaluates it for input that is not
contiguous.

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

---------

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-11-01 17:22:32 +01:00
Niels Lohmann aecbef3949 Binary readers: swap the bytes of floats with a single byteswap (#5976)
* Binary readers: swap the bytes of floats with a single byteswap

byte_swap reversed float and double values byte by byte. GCC does not
merge that loop into one bswap, and C++23's std::byteswap accepts only
integers. Overloads for float and double now copy the bits into a
uint32_t/uint64_t, call detail::byteswap, and copy them back. This
applies to every binary reader that uses get_number.

In the CBOR reader, the single- and double-precision float cases call a
non-inlined helper. Without it, GCC stopped inlining the stream
adapter's get_character() into parse_cbor_internal, which made reading
from a std::istream about 0.5 % slower.

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

* CBOR reader: inline get_cbor_float() and always inline get() instead

The never-inlined get_cbor_float() costs a call for every float read
from input without bulk access: reading canada.json from CBOR through a
FILE* became 5.6 % slower on Apple clang in the benchmark suite. The
helper existed only because GCC 13 stopped inlining the stream adapter's
get_character() into parse_cbor_internal. Always inlining
binary_reader::get() fixes that as well.

callgrind, all binary formats on buffer, std::istringstream and FILE*
input (canada and citm_catalog): GCC 13 0.986-1.003, GCC 16 0.994-1.006,
Clang 23 identical. Apple clang suite: FromBinaryFile/cbor/canada 0.939,
geomean of the 53 binary reader rows 0.998.

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

---------

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-11-01 17:22:32 +01:00
Niels Lohmann 6c3ab966d3 CBOR reader: read runs of scalar array elements in one loop (#5975)
* CBOR reader: read runs of scalar array elements in one loop

When a definite-length CBOR array opens and the input is contiguous, read
the integers, floats, booleans, and nulls that follow in a tight loop
instead of going through parse_cbor_internal's container logic and
parse_cbor_value's dispatch for every element. The loop stops at any other
kind of value and when fewer than 9 bytes are left; those values are read
by the general path exactly as before. Non-contiguous inputs are not
affected (tag dispatch on the bulk-scan capability).

Also pass a member empty string as the number source to number_float
instead of constructing a std::string for every float.

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

* CBOR reader: address review of the scalar-run reader

- parse_cbor_scalar_run: set the size explicitly in every case that
  reads a value, instead of relying on a default that every other case
  overwrites.
- Remove cbor_scalar_follows(): parse_cbor_scalar_run already returns on
  the same conditions, and without the pre-check SAX canada needs another
  8.5 % fewer instructions with GCC 13 (0.915 against the previous
  version), with no row more than 0.5 % worse (Mac and GCC).
- Restore the comment on why parse_cbor_internal copies the container
  frame.

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

* CBOR reader: enter the scalar run only when a scalar follows

An array of containers or strings called the out-of-line run start once per
array only to leave it at once; on nested data (arrays of objects) that call
made reading slower than before the run reader. enter_cbor_array now tests the
first byte and the remaining length inline and calls the run only for a
scalar, so the run's loop condition moves to the end (do-while).

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

* CBOR reader: mark the initial accepted in the scalar run as a false-positive dead store

ci_infer reports DEAD_STORE for 'bool accepted = true;' in
parse_cbor_scalar_run because every case assigns accepted before it is read.

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

* CBOR reader: drop the scalar pre-check before the run

enter_cbor_array calls the run directly again, and parse_cbor_scalar_run
tests the remaining count and length at the top of a while loop; its own
switch already leaves on any value that is not a scalar. The MessagePack
reader is built the same way.

Instructions per repetition, new/old: clang SAX canada 0.983, read canada
0.993; GCC 13 read canada 0.997, the other rows at most 1.004.

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

* CBOR reader: say why the initial accepted in the scalar run stays

Infer's DEAD_STORE report is right, not a false positive: every case that
reaches the read assigns accepted. The initializer is kept for clang-tidy's
cppcoreguidelines-init-variables.

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

* CBOR reader: give the scalar run the bulk tag instead of a wrapper

parse_cbor_scalar_run takes the bulk-scan tag itself and is the function that
is kept out of line, so the one-line parse_cbor_array_start wrapper goes, as
the UBJSON typed run already does.

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

* CBOR reader: start the scalar run's accepted at false

Infer ignores dead stores of 0 (--liveness-ignored-constant defaults to "0"),
and false is 0 to it, so the suppression and its comment go.

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

* CBOR reader: let the scalar run find its array itself

parse_cbor_scalar_run reads container_stack.back() in its bulk version, so
the caller no longer evaluates it for input that is not contiguous.

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

---------

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-11-01 17:22:31 +01:00
Niels Lohmann 162eda2574 json_view: skip the digits of a fraction 16 bytes at a time (SSE2) (#5971)
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-11-01 17:21:19 +01:00
Niels Lohmann 1a018577cc json_view: accept() checks the text without writing an index (#5970)
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-11-01 17:21:06 +01:00
Niels Lohmann 76001c6b4c BSON reader: find C-string terminators 8 bytes at a time, skip array element names (#5968)
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-11-01 17:20:54 +01:00
Niels Lohmann 3fd3e0fdaa json_view: dump and read canada.json-style floats faster (batched float decisions) (#5908)
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-11-01 17:20:29 +01:00
Niels Lohmann 9c349b1d7c Write integers of 17 to 20 digits eight digits at a time in dump() (#5964)
#5634 made dump() write integers below 10^16 eight digits at a time; larger
ones still took the two-digits-per-division loop and count_digits(). Random
64-bit integers almost all have 17 to 20 digits (99.9 % of signed_ints.json
and unsigned_ints.json), so Dump/signed_ints and Dump/unsigned_ints gained
only 1.4x over 3.12.0, against 2.3x for small integers.

A 64-bit magnitude is now written as its first one to four digits and two
groups of eight. Wider magnitudes (__int128 and class types, #5805) keep the
loop: number types of at most 64 bits are selected by type, so no comparison
is reported as always true; for others the value is compared. The sign
handling of #1447/#5815 (remove_sign() into number_magnitude_t) is unchanged.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-31 13:54:45 +01:00
Niels Lohmann 4fe670b5f4 json_view: decode chains of unicode escapes in a loop (#5969)
After the first \uXXXX escape of a string, slow_string() now decodes the
escapes that follow it directly, while the next six bytes are \u and four hex
digits that are not a surrogate, instead of going round its main loop for each
of them (that is how Python's json.dumps writes non-ASCII text by default).
A surrogate, a bad digit, or fewer than six bytes leave the position at the
backslash: the main loop handles them as before and reports the same error at
the same position.

twitterescaped.json (simdjson-data, 549 KB, 33,036 escapes), json_document::parse(),
A/B in one binary, 6 code layouts, time after / before:

- Apple M1 Max, Apple clang 21: 0.897
- x86-64 Haswell, GCC 16.2: 0.907
- x86-64 Haswell, Clang 23: 0.910

The other files of the benchmark set (twitter, citm_catalog, canada, gsoc-2018,
apache_builds, instruments, tree-pretty, github_events, random, update-center,
semanticscholar-corpus, twitter_timeline) stay within the noise of each machine.

New test: chains of every length from 1 to 40 of escapes that give one, two,
and three bytes of UTF-8, followed by the end of the string, text, escapes,
surrogates, bad digits, and cut in every place, in keys and in values, against
json::parse().

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-31 13:54:02 +01:00
Niels Lohmann ea03d601af json_view: comparison without temporaries and a faster image float check (#5890)
* Compare json_view values without a vector per container and a basic_json per number

operator== of views (view/view, view/json, and editable documents) built two
vectors of members for every object it entered, sorted them with stable_sort
for every object, and converted each number to a basic_json value. It now:

- keeps the members of all open objects in one vector (reserved with
  geometric growth, so that nested objects do not reallocate), and orders
  them by insertion sort for up to 16 members, or not at all when the keys
  ascend already;
- compares numbers of one type directly, and builds a basic_json only for
  numbers of different types;
- compares short texts (keys, numbers, most strings) with two overlapping
  loads (bytes_equal(), in node.hpp);
- first walks both documents in lockstep, in the order of their text, which
  finds most pairs of equal values without the work of the comparison. The
  walk only enters an object if the comparison would visit its members in the
  same order (the object type keeps the order, the keys ascend, or all values
  are scalars), so a difference is never found later than before, and it
  records the containers it found different, so that the comparison does not
  walk them again;
- rejects values of different types and arrays of different sizes before any
  of this, and, for an object type that keeps the order, objects whose first
  (up to four) members have different keys, which ends a comparison that
  differs near the start without preparing the members.

Results are unchanged: numbers compare by value across types, duplicate keys
resolve as parse() resolves them, and objects compare in document order for
ordered_json and by key otherwise.

Instructions of one comparison of a document with an equal copy, macOS arm64
(develop -> now), json_document / ordered_json_document / editable:

  twitter    16.1M -> 7.0M   17.7M -> 1.5M    16.6M -> 7.3M
  citm       45.0M -> 3.4M   47.0M -> 3.2M    45.7M -> 4.3M
  canada    111.4M -> 13.7M  111.4M -> 13.7M  113.3M -> 15.0M
  jeopardy   26.2M -> 3.7M   27.3M -> 3.7M    26.6M -> 12.1M

and of a view with a basic_json value:

  twitter    11.4M -> 5.9M   11.2M -> 7.3M    11.6M -> 5.9M
  citm       33.9M -> 9.7M   32.6M -> 9.1M    34.6M -> 9.8M
  canada     92.9M -> 32.1M  92.9M -> 32.1M   93.9M -> 32.8M

and Linux instruction counts (GCC 13 / Clang 18) of the same comparisons:

  document with an equal copy   json_document     ordered_json_document   editable
    twitter                     -49 % / -52 %     -89 % / -89 %           -48 % / -50 %
    citm                        -90 % / -89 %     -91 % / -90 %           -88 % / -87 %
    jeopardy (4,000 questions)  -85 % / -85 %     -86 % / -86 %           -46 % / -49 %
  view with a basic_json value
    twitter                     -41 % / -45 %     -28 % / -35 %           -45 % / -44 %
    citm                        -63 % / -65 %     -63 % / -66 %           -65 % / -64 %
    jeopardy                    -39 % / -43 %     -14 % / -24 %           -44 % / -43 %

A sweep that places one difference at about 2,100 positions of eight
documents (a token at an even spacing, the first and last tokens, the first,
middle and last member of the root removed, one appended, the document
wrapped) in five kinds of comparison (view/view of read-only and of editable
documents, view/json, json_document, editable/view) finds the same results as
before and no placement slower on the Mac (Clang); on Linux no placement is
slower than 3 % (Clang and GCC).

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

* Check the float tokens of a json_document image without a sort and a scan of every character

load(image_check::full) checked every float token of an image by sorting
the token ranges, scanning the token character by character, and comparing
the digit layout with the node's. Now:

- the ranges are sorted only if they are not sorted already (save() writes
  them in the order of the nodes, so they are);
- a token of the shape [-]digits.digits whose digit counts are the ones the
  node records (nearly all of them) is accepted by checking its digits eight
  at a time, without the general scan;
- the general scan skips runs of digits eight at a time.

Damaged tokens are still rejected as before: the check accepts exactly the
tokens that the general scan accepts.

Instructions of load(image_check::full) (develop -> now):

  macOS arm64        canada 44.6M -> 30.9M (-31 %), jeopardy 11.3M -> 10.7M,
                     citm 10.4M -> 10.0M, twitter 5.06M -> 4.94M
  Linux GCC 13       canada -50 %, jeopardy -43 %, twitter -31 %, citm -28 %
  Linux Clang 18     canada -42 %, jeopardy -48 %, twitter -35 %, citm -32 %

image_check::bounds is unchanged (within 0.4 %).

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

* Rename names that Flawfinder takes for the file function open()

The comparison cursors' open() is now enter(), and a test's open and
close strings are head and tail.

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

* Fix the compiler and lint failures of the json_view comparison

- all_digits(): the lambda declares its constant itself; MSVC does not
  let a lambda without captures read a constexpr local of the function
- equal(): the frame's "in document order" index is a namespace-scope
  constant (document_order); the local constexpr npos in the default
  member initializers of the local struct crashed GCC 9 and MinGW GCC
  and was not found by MSVC
- keys_differ_early() keeps the first keys in std::arrays (cpplint:
  variable-length arrays; clang-tidy: C arrays), and the basic_json
  side's first_keys() is not noexcept (key() may throw)
- the numbers of one type are compared in an if chain instead of a
  nested conditional operator
- the dump test avoids C arrays and temporary string concatenations

View comparison instructions are unchanged (Apple clang, twitter, citm,
canada: -0.1 % to +0.1 %).

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

* Keep the byte comparison helpers in compare.hpp

Address review comments: bytes_equal() and bytes_less() move from node.hpp
to compare.hpp, their only user; key_less() no longer splits the comment of
resolve_indices() from its function; and the loop counters of bytes_equal()
and all_digits() are scoped to their loops.

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

* Dispatch on the compile-time conditions of the json_view comparison

MSVC (/W4 /WX) reported C4127 (conditional expression is constant) for
the template parameter EA and the object type's ordering in an if
condition; both are now tag-dispatched.

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

* Remove a nested duplicate guard from the json_view image test

clang-tidy reported the inner #if !defined(JSON_NOEXCEPTION) as
redundant (the test case is in the same #if) and a find() != npos, which
gets the NOLINT the other tests use.

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

* Mark Infer's null dereference in materialize() as a false positive

Infer (ci_infer, also red on develop since #5882) reports a null
dereference in json_sax_dom_parser::null() called from materialize(). The
member pointer the parser stores a value of an object in is set by the
key() before it, so it is not null there.

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

* Move the json_view comparison tests into their own file

With the tests this branch adds, the object file of unit-json_view_dump.cpp
got too large for the MinGW x64 assembler ("file too big"). The test case
"json_view comparison" is now unit-json_view_compare.cpp, unchanged and
also built with C++17.

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

* Build the DOM parser with Visual Studio 2015 again

Since #5882, the three VS 2015 jobs of AppVeyor fail on develop:
- the detection of keys that can be indexed instantiated std::hash for
  every string type, which VS 2015 rejects with a static_assert for a type
  it does not hash (alt_string): std::hash is now looked at only for
  objects in a vector
- the frame stack copied its frames with std::copy to a raw pointer, which
  VS 2015 reports as unsafe (C4996, an error with /WX): a loop now

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

* json_view: no per-object allocations in ordered_json comparisons

For an object type that keeps the order of its members (ordered_json),
resolve_indices() allocated a vector per compared object, and
resolve_members() two. They now use one working vector owned by equal(),
whose capacity is reused, and resolve_indices() needs none when the keys
are unique. resolve_members() sorts small objects by insertion, as the
other paths do.

Instructions per comparison (callgrind, GCC 13 and clang 18, x86-64):
twitter, ordered_json view == ordered_json: 0.939 / 0.941; 20000 small
objects with a duplicate key: 0.741-0.768; all other rows (json,
citm_catalog, canada, view == view) within 0.988-1.003.

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

---------

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-30 15:19:42 +01:00
Niels Lohmann 0b91f9ddd8 json_view: check_utf8 skips well-formed runs with the parser's string scan (#5926)
* json_view: check_utf8 skips well-formed runs with the parser's string scan

Strings of 32 bytes or more that are written into an editable document
are validated with scan_string_run(), which skips well-formed UTF-8 16
bytes at a time; the byte-wise check runs only from where the scan found
ill-formed UTF-8, to report the same type_error.316. Shorter strings
keep the byte-wise check (inlined with a constant start, so that this
path is the code it was), where the vector scan costs more than it
saves.

set()/push_back() of strings of 32 bytes or more take 0.29-0.76 of the
time (x86-64 GCC, averaged over code layouts) and 0.25-0.80 (AArch64
clang); shorter strings take 1.5-4 % fewer instructions; the json_view
rows of bench_edit execute at most 0.04 % more instructions.

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

* tests: avoid sign conversion in json_view_edit UTF-8 check

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

* json_view: use while in check_utf8_bytewise

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

---------

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-30 15:17:55 +01:00
Niels Lohmann 0115bb47b3 Name the source and license of adapted code in the file comments (#5965)
The files with code adapted from fast_float, Zmij and simdjson carried the
authors' SPDX copyright lines, but their file comments did not say what
was taken or under which license: number_parse.hpp, to_chars.hpp,
simd_scan.hpp and view/simd.hpp now do, as zmij.hpp and the yyjson-based
view files already did. README and the license page now also name
fast_float's eight-digit parsing and the lexer's use of simdjson's UTF-8
check. Comments only.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-30 15:17:24 +01:00
Niels Lohmann 54f6b3ef06 json_view: source positions in materialize() with JSON_DIAGNOSTIC_POSITIONS (#5945)
* json_view: source positions in materialize() with JSON_DIAGNOSTIC_POSITIONS

With JSON_DIAGNOSTIC_POSITIONS, materialize() now gives every value the
start_pos()/end_pos() that basic_json::parse() would give it, so exceptions
about materialized values name the same bytes (#5864).

- json_sax_dom_parser takes the lexer type as a defaulted template
  parameter; materialize() passes position_source, which reports the
  positions it derives from the index. diagnostic_positions treats npos as
  "no position" and keeps ranges all-or-nothing.
- Strings with escapes keep the offset of their opening quote plus one in
  `next` (only with the macro); materialize() scans from there to the closing
  quote. The end of an array or object is found by scanning from the end of
  its last element over whitespace, comments and a trailing comma.
- In editable documents, values written by edits, arrays and objects whose
  elements changed, and containers whose last element has no position get
  none. Images keep the flag is_new, and load() checks that `next` of a
  string is within the text.

Nothing changes on the parse path without the macro. The view's own
exceptions still carry no byte range, so the tests that compare them with
those of materialized values skip it under the macro, as they skip the path
under JSON_DIAGNOSTICS.

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

* Indent comment in unit-json_view_from_json.cpp

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

* Address review: clearer position code and docs

- position_source gets clear(); set_scalar() returns early for new values,
  switches on node_kind, and uses no local copies; the one position_source
  per materialize() call is documented
- no npos + 1 for containers without a position; a comment on why the end
  of a container is reported as its closing bracket
- less duplication under #if in materialize() and the builder
- diagnostic_positions sets npos explicitly
- docs: positions of basic_json values after changes, positions in images
  depend on how the document was parsed, when next is set, and the cost of
  positions while parsing

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

* Share the comment scanners of the view builder with materialize()

skip_line_comment() and find_block_comment_end() in scan.hpp are used by
the builder's comment() and by position_source::container_end(), which
had its own copy.

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

* Address review: if/else for container positions, clearer next field

- the opening bracket of a container sets positions with an if/else instead
  of a ternary, and the frame takes its start from positions
- the closing bracket of a container is found in nested if/else; the parent's
  last_end is taken from positions, so it is npos whenever no range is set
- architecture.md: the next field reads "or 0 if it was not; all other
  values: 0" instead of "else 0; otherwise 0"

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

* Fix GCC unused-result and clang-tidy raw-string findings in unit-json_view_positions.cpp

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

---------

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-28 20:24:49 +01:00
Niels Lohmann 091c10d4a5 Fix self-aliasing in json_pointer::operator/= and patch_inplace (#5936)
* Fix self-aliasing in json_pointer::operator/= and patch_inplace

json_pointer::operator/=(const json_pointer&) passed iterators into its
own token vector to insert() when a pointer was appended to itself
(p /= p), which is undefined behavior; libstdc++ produced "/a/b//" for
"/a/b". The pointer now appends a copy in that case.

basic_json::patch_inplace iterated the patch while changing *this, so
j.patch_inplace(j) read freed memory. It now applies a copy of the
patch when the patch is the value itself. A patch stored inside the
value remains undefined behavior and is documented as such; copying the
patch unconditionally would double the time of a large patch.

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

* Fix JSON_DIAGNOSTICS test crash and clang-tidy hit in patch_inplace self-aliasing

The spare-capacity test reallocated non-empty elements through get_ref(), which leaves stale parent pointers under JSON_DIAGNOSTICS; reserve while the array is empty instead. Suppress performance-unnecessary-copy-initialization for the copy that is needed because *this is modified.

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

* Detect a patch stored inside the patched value with JSON_DIAGNOSTICS

patch_inplace applied a copy only when the patch was the value itself. With JSON_DIAGNOSTICS the parent pointers make it cheap to also detect a patch nested inside the value, so that case is handled the same way. Without diagnostics it stays documented undefined behavior.

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

* Silence misc-const-correctness for patch_aliases_this

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

* Fix clang-tidy findings in the operator/= self-append test

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

---------

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-28 20:23:55 +01:00
Niels Lohmann 78a0687147 Strong exception guarantee for operator[](json_pointer) (#5940)
* Keep the value unchanged when operator[] with a JSON pointer throws

The non-const operator[](json_pointer) is documented with strong exception
safety, but get_unchecked created intermediate values while walking the
pointer and kept them when a later reference token failed, e.g.
json j; j["/a/99999999999999999999999"_json_pointer] threw 404 and left
{"a":[]}; padding an existing array or appending with "-" behaved alike,
and so did std::length_error/std::bad_alloc from a huge index.

get_unchecked now only walks existing values up to the last reference
token. The last token's key insertion or array growth is strongly
exception safe by itself. Any other change goes through
get_unchecked_create, which records the one change it makes to an existing
value (null converted, key inserted, array grown) in a RAII guard and
reverts it if a later step throws; everything else it creates lies below
that change. The guard needs no try/catch, so JSON_NOEXCEPTION builds are
unaffected. Successful calls create the same values as before.

Docs: state the guarantee in the exceptions list and version history of
operator[], fix the complexity of the pointer overloads of operator[] and
at, and warn that padding arrays up to an untrusted index allocates memory
proportional to the index (operator[].md, untrusted_input.md).

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

* Make the strongly exception-safe pointer operator[] faster than before

The previous commit made get_unchecked strongly exception safe but slower
with GCC 16 when it creates values (up to +6 % instructions for appending
with "-"). This restructures it so that no benchmark row is slower than
before the strong guarantee, with GCC 16, Clang 22 and Apple Clang.

- get_unchecked walks existing values in one loop that inserts nothing.
  The last reference token is resolved in that walk: "-" appends with
  emplace_back(), an index grows the array with operator[], and a missing
  key is inserted with emplace_hint() at the position the walk's
  lower_bound() found, so the key is searched once.
- With std::less<string_t> or std::less<> as comparator, the walk checks
  the key at the lower bound for equality instead of equivalence, which is
  the same for these comparators and cheaper.
- get_unchecked_create (not inlined) handles all other changes. Its guard
  swaps a null value with a fresh null value instead of copying it and
  reverts the change in a non-inlined function, so a successful call pays
  one compare for it. As every null value converted afterwards is a fresh
  one, it is converted in place instead of assigning a new array or object.
- Keys are added to new objects with emplace(), which also replaces the
  basic_json::operator[] call for ordered_json.

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

* Fix rollback of pointer operator[] for unusual object and string types

Follow-up to the strong exception guarantee of the non-const
operator[](json_pointer):

- get_unchecked_create assumed that emplace() always inserts the key that
  the walk did not find. For object types whose lookup and emplace()
  disagree (e.g. a copied fifo_map), nothing was inserted, the rollback
  erased the existing member, and the walk continued with a value of the
  wrong type (assertion, type_error.305, or a crash). It now checks the
  result of emplace(), arms the rollback only if a key was inserted, and
  otherwise continues the walk with the member found, as basic_json's
  operator[] does: such pointers throw out_of_range.404 and leave the value
  unchanged, as before the strong guarantee.
- The rollback erased the inserted key by key, which converts string_t to
  object_t::key_type and may allocate inside a noexcept function
  (std::terminate on bad_alloc with custom key types). It now erases by the
  iterator emplace() returned, and shrinks a grown array with erase() at
  the end instead of resize(). The documentation states the remaining
  requirement for custom template parameters.
- Creating values no longer calls string_t::begin(), so the non-const
  operator[](json_pointer) compiles with string types that lack it (as the
  alternative string type of the tests).
- Correct the @throw lists of get_unchecked and get_unchecked_create.

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

* Address review comments on operator[](json_pointer) rollback

- undo() shrinks the array with resize() instead of erase()
- comments say what "will be" done in get_unchecked_create
- tests: avoid a clang-tidy performance-unnecessary-copy-initialization
  hit (unit-alt-string) and the word "access" in section names, which
  Flawfinder flags as race/access

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

* Let the pointer rollback guard call undo() unconditionally

The check in the destructor and JSON_HEDLEY_NEVER_INLINE on undo() made no
measurable difference: instruction counts of j[ptr] are identical with
GCC 13 -O3 and within 0.4 % with clang, timings are within noise.

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

---------

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-27 17:15:55 +01:00
Niels Lohmann 21ec9bd801 json_view: fewer allocations when parsing small documents (#5915)
- Size the buffer of decoded strings on its first growth from the input (a
  quarter of it plus 16 bytes, at most 4 KiB) instead of 272 bytes, so that a
  document with escapes does not grow it twice, with a zero-filled copy each
  time.
- Allocate the node index of documents with an estimate of up to 1024 nodes
  (was 256) together with the header, which saves one allocation. When the
  estimate is too low (dense numbers), that block stays unused: at most 16 KiB
  instead of 4 KiB. shrink_to_fit() cannot release it separately; the
  documentation says so.

Fresh parse of a 2.5 KB minified tweet: 993 to 958 ns (-3.5 %), traverse and
select -3 %, with no row consistently slower (Apple M1 Max, 30 rounds, three
runs). Dense numeric documents parse about 9 % faster and keep up to 16 KiB
more memory.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-27 07:22:49 +01:00
Niels Lohmann 9e67bfa115 json_view: the library's std conversions read views directly (#5923)
* json_view: the library's std conversions read views directly

The library's from_json() overloads (containers, maps, std::array, C
arrays, pairs, tuples, optional, valarray, forward_list, enums, binary,
paths, and scalars) accept views: their traits use the view's
basic_json type, and the few accesses that differ (get_ptr) go through
small helpers. from_json() of a view now finds them; only the probe
still looks up by ADL only. get<T>() of a view thus converts these types
without materialize(), with the same values and exceptions; from an
object, a repeated key keeps the last value, as parse() does.

The view keeps its direct paths for vectors of the types it converts
directly (faster than from_json()) and for containers of views; its
other vector and map paths are replaced by from_json(). For basic_json,
std::valarray and std::forward_list are read in one pass (40 % and 3.5 %
fewer instructions); all other conversions are unchanged.

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

* json_view: enable_if_not_view_t instead of '!' in the from_json() templates

astyle spaces out the template argument list when it contains a negation;
the alias spells the condition with negation<> and leaves the lines alone.

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

* json_view: compact the template parameter lists astyle had spaced out

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

---------

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-26 20:13:31 +01:00
Niels Lohmann e5fe4ebdd2 json_view: from_json() of the macros reads views directly (#5922)
get<T>() and get_to() of a view call T's from_json() with the view itself
when that from_json() accepts views but not an unrelated probe type, and
fall back to materialize() otherwise. The from_json() functions of the
NLOHMANN_DEFINE_TYPE_*, NLOHMANN_DEFINE_DERIVED_TYPE_* and
NLOHMANN_JSON_SERIALIZE_ENUM(_STRICT) macros accept basic_json values and
views; a derived type whose base reads only json reads the base part
through materialize(). The library's own from_json() overloads are not
called with views: from_json() of a view (and of the probe) only looks up
functions by ADL.

New public trait nlohmann::is_json_view<T>, and the member type
basic_json_type of basic_json_view. With duplicate keys, the members of
such a T are those the view's lookups find (the first ones).

bench_decode.cpp measures decoding into structs (4-6x faster than
materialize().get<T>() on twitter, citm_catalog, and synthetic records).

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-26 20:13:31 +01:00
Niels Lohmann 5a2819c940 json_view: one SIMD macro set with the library (#5921)
The view's vector code follows JSON_NO_SIMD, like the lexer and the float
writer, and skips the CPU check of SSSE3 when the code is compiled for
SSSE3 anyway (__SSSE3__), like the lexer. JSON_VIEW_NO_SIMD and
JSON_VIEW_USE_SSSE3 and their ABI tags _vns and _vssse3 are removed; they
were never released. JSON_NO_SIMD keeps its tag _ns.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-26 20:13:31 +01:00
Niels Lohmann 4cdfa6d0f4 json_view: no save() and load() on big-endian targets (#5920)
The image format is little-endian only. Instead of throwing
type_error.320 at runtime, save_image(), load_image() and the members
save() and load() do not exist on a big-endian target, so a call fails to
compile, like set() on a read-only document. type_error.320 remains for
saving a discarded document.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-26 20:13:30 +01:00
Niels Lohmann 731f1b5bfb json_view: view_mode enum instead of bool Editable, node_kind for node::kind (#5919)
* json_view: view_mode enum instead of bool Editable, node_kind for node::kind

basic_json_document and basic_json_view take a view_mode (read_only, the
default, or editable) instead of a bool: basic_json_document<json, true>
did not say what true means. The shortcut aliases are unchanged.

The kind of a node is a node_kind (the value_t values plus link, 10 as
before), which removes the static_cast<std::uint8_t>(value_t::...) of
every comparison. The node and image layouts are unchanged.

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

* json_view: node_kind in the node writers, spell out read_only, comment fixes

The builder and the edit functions take and store a node_kind instead of
casting a value_t; the numbering assertions and the comments now speak of
node_kind, and the link kind notes that it follows value_t::discarded.
The read-only aliases name view_mode::read_only like the editable ones.
view_mode.md says the mode is a compile-time property of the type.

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

* json_view: views of read-only documents convert to editable views

A read-only document has no edits, so a view of it reads correctly as a
view of an editable document before its first edit. The implicit
conversion lets a function taking a json_editable_view accept the views
of both modes. There is no conversion the other way: a read-only view of
an editable document would read wrong values after the next edit.

The mode comparisons in the cross-mode operator==/!= use an
is_other_mode trait, which astyle keeps compact.

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

---------

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-26 20:13:30 +01:00
Niels Lohmann 60107eda3f Read BJData ND-arrays of float16, restrict ND-array char to 0..127, correct BJData docs (#5931)
* Read ND-arrays of half floats and enforce the char limit in ND-arrays

BJData N-dimensional arrays with element type 'h' (float16) failed to
read with a misleading parse_error.112, because the reader's dtype name
table lacked 'h'. It now maps to "half", the JData name. The writer still
does not pack "half"; such an object is written as a plain object and
reads back equal.

BJData limits 'C' (char) to 0..127 in Draft 2 and Draft 3, and the 1-D
reader enforces this, but ND-arrays with _ArrayType_ "char" wrote values
up to 255 as 'C' elements and read them back without a check. The writer
now only packs values in 0..127 (others fall back to a plain object that
round-trips), and the reader rejects 'C' elements above 127 with
parse_error.113 like the 1-D reader.

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

* docs: correct and complete the BJData documentation

Verify the BJData chapter against the library and the Draft 2/3/4
specifications and fix what did not match:

- bjdata.md: correct the list of unused markers (N, not Z), the ND-array
  example (3x2, not 2x3), the conditions under which an object is packed
  as an ND-array (exactly three keys, row vectors, float-only elements for
  single/double, char 0..127, byte only in Draft 3), the binary table row
  and notes (which flag/draft combinations write [$B), the "$" type
  restriction (Draft 3, Z is excluded too), the H marker in the
  deserialization table, and the claim of a complete deserialization
  mapping. Document the supported drafts, that Draft 4 (SoA containers,
  extension type E) and column-major ND-arrays are rejected, ND-arrays of
  half floats, duplicate object keys, and link the Draft 3 specifications
  instead of master.
- Add an API page for basic_json::bjdata_version_t with an example, and
  link it from the nav, the API index and to_bjdata.
- Update binary_formats/index.md and binary_values.md, which still claimed
  that BJData has no binary type, and fix a wrong byte comment there.
- Document parse_error.115 and the out_of_range.408 cases for from_bjdata,
  the precise other_error.502 condition for to_bjdata, and reword the note
  on truncated unsigned integers in exceptions.md (only ND-array elements
  were truncated before 3.13.0).

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

* Regenerate single_include and apply astyle

Result of make amalgamate (including make pretty) for the preceding changes.

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

* Address review of the BJData documentation

The $ type restriction exists since Draft 2 (Draft 3 added B), $ requires a count, ND char above 127 is rejected on read, and the new API page is listed in alphabetical order in the nav.

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

* docs: format tables, use the Oxford comma

Reformat the tables changed by this PR (BJData serialization and
deserialization mappings, completeness and binary-value tables) so all
rows are aligned, and add the Oxford comma to lists of three or more
items in the added text.

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

---------

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-26 18:25:46 +01:00
Niels Lohmann dc768a7d5d Fix BSON binary subtype 0x02 and check the declared document size earlier (#5930)
* Write and read the inner length of BSON binary subtype 0x02

The BSON specification defines the payload of the "binary (old)" subtype
0x02 as an int32 followed by that many bytes. to_bson wrote the plain
payload instead, so decoders such as pymongo and libbson-based readers
rejected the bytes, and from_bson returned the inner length as part of the
payload (documented as lenient behavior in gh-5333).

The writer now emits the outer length (payload + 4), the subtype, the inner
int32 holding the payload size, and the payload. The reader requires an
outer length of at least 4 and an inner length equal to the outer length
minus 4 (the cases the bson-corpus lists as decode errors), reports parse
error 112 otherwise, and returns only the payload. Both directions change
together so that the round trip keeps working.

The single-reservation fast path for scalar entries declines subtype 0x02
because it has no room for the inner length.

This is a deliberate exception to the opt-in rule for behavior changes:
the previous output was invalid BSON.

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

* Check the declared BSON document size before reading its content

The BSON reader compared a document's declared size with the number of bytes
read only when it reached the terminator. The declared size never bounded
the reads, so a SAX handler saw the keys and values of a document whose size
was too small before parse error 112 was reported.

The container frame now stores the position where the document ends
according to its declared size. open_bson_document rejects a size below 5
(size prefix plus terminator) and an embedded document that does not end
before the terminator of its enclosing document; the element loop rejects an
element whose type byte leaves no room for the name terminator and the
document terminator. The terminator check stays and still catches a declared
size that is too large. No input that was accepted before is rejected now;
documents with a wrong size are reported earlier, with fewer SAX events, a
different byte position and, in three cases, a different message. The error
id (parse_error.112) is unchanged and strict=false still does not skip the
check.

The tests that asserted the old messages and positions are updated, with the
outer sizes of two inputs corrected so that they still exercise the embedded
document. New tests cover the SAX events, a size below 5, and an embedded
document that fits exactly.

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

* Document BSON subtype 0x02, document size checks, and lenient reads

Describe the inner length of binary subtype 0x02 that to_bson now writes and
from_bson checks and removes. Add the document size checks (parse_error.112,
not affected by strict=false) to bson.md and from_bson.md, and extend the
list of lenient reads with the UUID and MD5 payload lengths (not checked),
duplicate keys (last value wins), embedded NUL bytes in strings, and the
ignored trailing bytes with strict=false. State that the members of an object
are written in iteration order.

Correct the statement that element names are never validated on read: they
are checked and sanitized like string values by the error handler. Add the
BSON message to the examples of out_of_range.415 and type_error.321, the
subtype limit of 255 to the binary values page, CBOR to the formats that use
byte_container_with_subtype, and fix a typo in the incomplete mapping box.

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

* Regenerate single_include and apply astyle

Result of make amalgamate (including make pretty) for the preceding changes.

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

* Address review of the BSON documentation

Describe exactly when a too small document size is detected and note that subtype 2 data written by earlier versions is not readable.

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

* docs: use the Oxford comma, drop discarded-value remarks

Add the serial comma in a list added by this PR and remove the BSON
example of type_error.321 (with the type_error.317 remark) so the docs do
not mention discarded values for BSON; restore the original singular
heading of that section. No tables were changed by this PR.

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

* Fix -Weffc++ in the BSON recorder test and a clang-tidy use-auto hit

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

* Fix clang-tidy readability-redundant-member-init in BSON test

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

---------

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-26 18:25:46 +01:00
Niels Lohmann 0c3570d44a Validate the UBJSON/BJData container type marker for count 0; fix UBJSON docs (#5929)
* Validate the optimized-container type marker for count 0 in UBJSON and BJData

The '$' type marker of an optimized container was only checked when an
element was read, so containers with count 0 accepted any marker:
`[$x#i0`, `{$x#i0` and `[$E#i0` parsed as empty containers although a
non-empty container with the same marker is rejected and the UBJSON
specification requires a legal marker after '$'.

get_ubjson_size_type() now checks the marker right after '$' against the
allowed set (UBJSON: Z N T F i U I l L d D H C S [ {; BJData: B U i u I m
l M L h d D C, with the existing exclusion of T F Z N S H [ {) and reports
parse_error.112 "marker ... is not a permitted optimized array type".

Input that was accepted and is now rejected: an optimized container with
count 0 and an invalid '$' type marker. Valid input is unaffected. Two
existing tests that used an invalid marker incidentally ("[$#" and a
negative-count case) were adapted.

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

* Correct and complete the UBJSON documentation

Fix statements that disagree with the behavior (checked with probes):
- `Z` is null; the unused marker is `N`.
- `$` requires `#`; use_type with use_size=false throws other_error.502 only
  for non-empty arrays, objects and binary values.
- NaN and infinity are written as IEEE 754 float64 and read back unchanged;
  the UBJSON specification encodes infinity as null.
- `H` is documented (semantics, parse_error.115, out_of_range.406); the
  "complete mapping" claim is qualified.
- use_type "same type" means same marker.
- Long Z/T/F arrays lose only the `$` annotation; the `#` count and the
  element markers are kept.
- from_ubjson lists the 112, 113, 115, 406 and 408 causes that occur for
  UBJSON, without the BJData-only ND-array wording.
- Duplicate object keys keep the last value; the `$` type marker is
  validated even for count 0.
- Smaller fixes: float32 row, "map" -> "object", https link, exception 110
  strict case, to_ubjson history of discarded values.

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

* Regenerate single_include and apply astyle

Result of make amalgamate (including make pretty) for the preceding changes.

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

* Address review of the UBJSON documentation

Clarify that empty containers carry no $ annotation of their own and note that a counted N object is not supported.

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

* docs: format tables, use the Oxford comma, drop discarded-value remarks

Reformat the two UBJSON mapping tables that this PR changed (uniform column
widths, padded cells), use the serial comma in lists of three or more in the
added text, and restore the original type_error.321 bullet in to_ubjson.md.

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

* Fix narrowing of the optimized-container count in BJData and UBJSON tests

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

---------

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-26 18:25:45 +01:00
Niels Lohmann d5da84249f Skip CBOR tags in front of map keys, validate indefinite text chunks, fix CBOR docs (#5927)
* Skip CBOR tags in front of map keys and validate indefinite text chunks

A tag in front of a text string map key was rejected with parse_error.113
even with cbor_tag_handler_t::ignore or store, although tags in front of
values are handled. The tags are now skipped iteratively before the key is
read; the handler error still rejects them.

The chunks of an indefinite-length text string were concatenated before
the single UTF-8 check, so a code point split over two chunks, or an
invalid chunk, was accepted. RFC 8949, Section 3.2.3 requires every chunk
to be valid on its own. With error_handler_t::strict, replace and ignore
each chunk is now checked; keep is unchanged. The chunks are appended with
append(ptr, len), so StringType needs nothing new.

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

* docs: correct and extend the CBOR documentation

Fix the negative-integer rows (they used MessagePack boundaries), the
number_integer range of the 0x1B row, and the half-precision entry in the
list of unused types; correct the NaN history (0xF9 since 3.8.0) and the
tagged-item wording (only the tag directly in front of a byte string is
stored, and only in the 0xD8..0xDB form). Document that to_cbor is not
RFC 8949 deterministic, that duplicate keys are accepted (last wins),
tags in front of keys, per-chunk UTF-8 validation, the exceptions
parse_error.113, out_of_range.406/408 of from_cbor, the pointer and
C array input traps, the partially written output on exceptions, and the
store/ignore results in the binary values example. Drop the claim that
the CBOR reader needs StringType::append(const StringType&) and
BinaryType::insert(pos, first, last).

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

* Regenerate single_include and apply astyle

Result of make amalgamate (including make pretty) for the preceding changes.

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

* Address review of the CBOR changes

Cite RFC 8949 Section 5.3.1 for duplicate keys, describe the out_of_range.408 condition precisely, rewrap a long line, and update the stale get_string comment (per-chunk UTF-8 check). single_include regenerated.

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

* docs: drop discarded-value remarks

Remove the mention that a discarded value cannot be serialized to CBOR
(type_error.321) from the exception-safety and mapping sections. The
integer table and all added prose already follow the table-format and
Oxford-comma rules.

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

---------

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-26 18:25:44 +01:00
Niels Lohmann 81d66291c5 Create objects for pointer tokens that cannot be array indices (#5358)
* create objects for tokens that cannot be array indices (#5357)

When operator[](json_pointer) traverses a level that does not exist yet,
the null value is turned into an array or an object depending on the
reference token. The check only tested whether all characters are digits,
so tokens that can never be a valid array index selected an array and
then failed:

- "01" (and any other token with a leading '0') threw parse_error.106
- the empty token threw out_of_range.404

Both tokens are valid object keys, and both work when the level already
exists as an object, so creating the level changed the outcome. Test the
token against the RFC 6901, Sect. 4 grammar for array indices instead, so
that such tokens create an object. This only affects pointers that threw
before.

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

* Clarify that the token 0 is a valid array index in operator[] docs

The note described valid array indices as "a nonempty sequence of digits
without a leading 0", which read literally excludes the token "0" itself,
contradicting both the code and the /foo/0/0/0 example in the next
sentence. Spell out the RFC 6901 grammar instead.

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

---------

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-26 17:13:48 +01:00
Niels Lohmann 2a56afc714 Fix VS 2015 build of the DOM parser (#5882) (#5916)
- Name std::hash only once the object type has emplace_new_key: VS 2015
  static-asserts on std::hash of a type without one (alt_string) instead of
  reporting a substitution failure (C2338).
- Replace the std::copy calls on frames by loops: VS 2015 reports raw
  pointers handed to std::copy as C4996, an error under /WX.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-25 12:08:58 +01:00
Niels Lohmann 3eae5680d6 from_json: number-first dispatch for arithmetic types, loop for std::array (#5902)
* from_json: number-first dispatch for arithmetic types, loop for std::array (#5891)

from_json(ArithmeticType&) now reads numbers through get_number_value() and
handles a boolean on a cold path, which puts the three number types first in
the per-element type dispatch.

get<std::array<T, N>>() always took the identity_tag overload, a pack
expansion of N calls j.at(i).get<T>() that clang unrolls into straight-line
code (about 28,000 instructions for N = 1000), so its speed depended on
inlining decisions in that body. For trivial element types, which cannot tell
default construction plus assignment from construction in place, it now fills
a std::array in a loop. That loop, shared with get_to(), checks the size once
and reads the inner array directly; a short array still converts the elements
it has and then throws the out_of_range error at() would throw.

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

* Skip the get_to result check without exceptions

Without exceptions, the get_to calls in CHECK_THROWS_WITH_AS do not run,
so the array keeps its initial values (ci_test_noexceptions).

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

* Make is_trivial_element a struct so astyle does not indent it

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

* Expect the element path in the std::array type-error tests with JSON_DIAGNOSTICS

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

* Shorten from_json_inplace_array so astyle aligns its parameters

The opening parenthesis of the previous name sat in column 41, beyond
astyle's default --max-continuation-indent of 40, so the continuation
lines fell back to a plain double indent.

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

* Use the compact template<...> style for the new from_json overloads

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

---------

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-25 06:17:51 +01:00
Niels Lohmann fe5e401870 Consolidate duplicated detail helpers and bodies (#5891) (#5901)
* Add shared detail helpers for the #5891 cleanup

Add detail::is_primitive(value_t), detail::hex4_lower(), detail::utf8_shape(),
detail::input_format_name(), detail::empty_input_message(), the exception ids
116, 319, 320 and 416 to detail::exception_id, and make
detail::is_ascii_copyable() constexpr. Later commits switch the duplicated
code over to them.

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

* 1.4: BSON writers share one write-pass UTF-8 sanitizer (#5891)

write_bson_entry_header and write_bson_string re-derived the error-handler
policy differently. Both now use sanitize_utf8_for_bson_write, which treats
strict like keep (the size pass already validated) and sanitizes replace/ignore
into the bytes the size pass measured. No context plumbing is needed.

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

* 2.1.1: one MessagePack container prefix helper (#5891)

Array and object prefixes differed only in the fix marker and the 16/32-bit
markers; both now delegate to write_msgpack_container_prefix. Output is
byte-identical.

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

* 2.1.2: one iterative walker for CBOR and MessagePack (#5891)

write_cbor_iterative and write_msgpack_iterative (and their *_value_or_push
helpers) were identical but for the head, scalar, and key writers. They are now
one template over a small policy struct, so everything inlines. BON8 keeps its
own walker (open string run, closing marker), noted in a comment.

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

* 2.1.3, 2.1.8: one UBJSON container start helper, shared frame base (#5891)

write_ubjson_start_array/_object are now write_ubjson_start_container<IsArray>,
keeping the array-only begin()+1 scan and excessive_valueless rule.
ubjson_frame derives from binary_container_frame instead of duplicating it.

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

* 2.1.4: write_bytes helper for the byte-string write sites (#5891)

The 13 oa.write_characters(reinterpret_cast<const CharType*>(x.data()), n)
sites now call write_bytes(const void*, size_t); copy_characters sites and the
buffer-based writes are untouched.

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

* 2.1.5: shared object-key writer for CBOR and MessagePack (#5891)

write_cbor_key and write_msgpack_key were the same SFINAE pair apart from the
string/scalar writers; both now delegate to write_object_key<Walk>. UBJSON key
and to_format_length stay as they are.

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

* 2.3.10: writer-side format names from input_format_name (#5891)

The CBOR/MessagePack/UBJSON/BSON/BJData/BON8 literals in throw_on_discarded and
throw_integer_out_of_range calls now come from detail::input_format_name; the
texts are identical, and UBJSON vs BJData still follows use_bjdata.

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

* serializer: constexpr ascii table, hex4_lower, dedupe helpers (#5891)

1.1: build ascii_copyable() at compile time from is_ascii_copyable and
test find_ascii_copyable_run against it for every byte. 1.2/2.5.4: use
detail::hex4_lower in both \uXXXX writers. 2.1.6: factor the repeated
flush/emit blocks in dump_escaped_impl into always-inline helpers.
2.1.7: comment why the escape copy does not use put_buffer.

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

* 1.6: use string_t-aware to_string/concat in meta() (#5891)

Replaces the four std::to_string sites; rendered text unchanged.

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

* 1.7: use detail::is_primitive in json.hpp switches (#5891)

has_no_children, set_parents, max_size and the two diff walkers.

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

* 2.2.1: factor insert()/iterator throw helpers (#5891)

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

* 2.2.2: share swap() overloads via swap_impl (#5891)

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

* 2.2.4: factor primitive reset and range check in erase()/range ctor (#5891)

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

* 2.2.6: share push_back array bodies via push_back_array_impl (#5891)

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

* 2.2.7: route parse/accept/sax_parse through *_impl helpers (#5891)

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

* 2.2.8: share the vector-returning to_* bodies via to_binary_vector (#5891)

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

* 2.2.10: merge destroy_string/destroy_binary into destroy_pointer (#5891)

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

* 2.4.1/1.7: exceptions: share what_impl, flatten diagnostics switch (#5891)

The four create() bodies build their message through one protected
static helper; the diagnostics parent walk handles array/object and
ignores all other types.

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

* 2.4.2/2.4.3/1.7: json_pointer: share slash and escape checks, drop primitive case lists (#5891)

The leading-slash and invalid '~' escape checks are shared helpers; the
reference-token walks test object and array first and treat everything
else as primitive.

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

* 1.7/2.4.9: iter_impl, iteration_proxy: drop primitive case lists, share compare preamble (#5891)

Object and array stay the first branches; everything else is the
primitive case. operator== and operator< share the different-container
check.

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

* 2.4.5/2.4.6: from_json: share get_number_value and reserve_if_possible (#5891)

The three number cases of get_arithmetic_value and the arithmetic
from_json share one helper (boolean stays accepted only by the latter);
the array and object reserve overload pairs become one.

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

* 2.4.8: ordered_map: share erase_impl between the key erase overloads (#5891)

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

* 1.7: json_pointer: flatten walk drops the primitive case list (#5891)

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

* 1.2/1.3/1.5/2.5.1/2.5.2/2.5.5: share helpers in the view code (#5891)

- detail::exception_id at every numeric id; throw_* helpers take it
- hex_byte, hex4_lower, utf8_shape replace local hex/table code
- throw_array_index_out_of_range/_past_end, throw_key_not_found
- has_native_float_format replaces the hand-written IEEE check
No change of messages, ids or output.

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

* 1.5: use utf8_shape in get_bon8_string, add exhaustive UTF-8 validator test (#5891)

get_bon8_string takes the valid range of the second byte from utf8_shape()
(0xF5..0xF7 stay errors, unget behavior unchanged). validate_one_utf8 keeps its
if-chain (hot bulk path); the new test checks decode, validate_one_utf8,
utf8_shape, json::accept and the BON8 reader against each other for every lead
and second byte.

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

* 2.3.1: get_cbor_sized_bytes for the CBOR chunk getters (#5891)

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

* 2.3.2: get_string_with_length for the plain-order string sites (#5891)

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

* 2.3.3, 2.3.4, 2.3.10: unsupported_key_type, empty_input_message, input_format_name in the readers (#5891)

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

* 2.3.7, 2.3.9: read_object_key and leave_container_and_check for CBOR/MessagePack/BON8 (#5891)

UBJSON keys (different getter signature) and its container tail stay as is.

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

* 2.3.5: json_sax_dom_error_state base for the DOM SAX parsers (#5891)

Holds errored, allow_exceptions, parse_error() and is_errored(). The scalar
handlers stay in each class (parse hot path).

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

* 2.3.6: table of control-character messages in the lexer (#5891)

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

* 2.3.8: finish_input helper for the strict-EOF block in the parser (#5891)

sax_parse keeps its if (result) guard and return value. Also adds the
clang-tidy NOLINT for the 2.3.6 message table.

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

* 2.5.7: share parse_array_index between json_pointer and json_view (#5891)

Move json_pointer::parse_array_index() and its status enum to namespace detail
(json_pointer keeps a forwarding member), and let the json_view pointer
resolution use it instead of its own copy of the RFC 6901 index grammar. Both
accepted the same tokens with the same outcome. Also update the comment on
detail::decode(), which listed four of the five UTF-8 validators and now points
to the test that keeps them in sync.

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

* Amalgamate (#5891)

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

* 2.4.5: keep the inlined number cases in from_json(ArithmeticType&) (#5891)

Calling get_number_value() from from_json(ArithmeticType&) made
GetArray<std::array<int, 1000>> 2.4x slower (it changes the inlining of the
std::array conversion), so that overload keeps its own switch, with a comment.
get_arithmetic_value() still uses the shared helper.

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

* 2.5.7: force-inline detail::parse_array_index (#5891)

Moving parse_array_index out of json_pointer stopped clang from inlining it
into the pointer resolution (JsonPointerAt/citm_catalog +17%,
JsonPointerAt/twitter +8%); JSON_HEDLEY_ALWAYS_INLINE restores the baseline.

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

* 1.5: keep get_bon8_string's own UTF-8 ranges (#5891)

Taking the second-byte range from utf8_shape() made BON8 decoding 2-3% slower
(FromBinaryShape/scalars, FromBinaryBuffer, alignment-pinned builds), so the byte
path keeps its hand-written ranges. The exhaustive validator test still checks
that it accepts the same sequences as the other validators.

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

* Amalgamate (#5891)

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

* Fix CI failures: constexpr, NRVO, cppcheck, IWYU (#5891)

- json_sax_dom_error_state::is_errored() cannot be constexpr: the class
  is not a literal type (GCC 4.8, GCC -Wpedantic, Clang 3.5).
- to_binary_vector: destroy the vector writer before returning, as the
  output_vector_sink sets the size of the vector in its destructor.
  Without NRVO (MSVC Debug in C++14 mode), the vector was moved out
  before it was resized.
- parser::sax_parse: return false instead of result after the early exit
  (cppcheck identicalConditionAfterEarlyExit).
- json.hpp: export detail/exceptions.hpp for IWYU, so json_view.hpp can
  name exception_id without including a detail header.

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

* Address review: throw helpers take input_format_t, simpler type checks

- throw_on_discarded() and throw_integer_out_of_range() take an
  input_format_t and call input_format_name() themselves
- has_no_children(), set_parents() and max_size() check array, then
  object, instead of calling is_primitive() first
- parse_impl() chains like accept_impl(); sax_parse_impl() uses if/else
- std::array for the control character messages; negation<> in
  write_object_key(); clarify the is_primitive() comment

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

* json_view: use exception_id in the value() overloads

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

* json_sax: assert the invariant of place_container for the static analyzer

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

---------

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-25 06:17:50 +01:00