With _ITERATOR_DEBUG_LEVEL > 0 (MSVC STL debug builds, clang-cl), containers
allocate inside noexcept functions, so a failing allocation terminates the
program: "test case CRASHED: Terminate handler called" in the sax_parse
subcase of #5985. The sweep test of #6000 has the same guard.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
The `!negative ||` that #6006 added to the digit test of the number scan has
a constant left operand in the template (negative is a template argument), so
MSVC reports C4127 under /WX in builder.hpp(1177). Restore the plain test; the
branch behaves the same.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
Keeping the byte range of the root value (#5990) dropped the found flag of
value_path(), but a root has no tokens and is found, while a view of a value
that was removed from the document is not found. Without the flag, the
removed value got the bytes of its stale node, and
"json_view exceptions name the path and the bytes of the value" failed on
the macOS jobs with JSON_DIAGNOSTICS and JSON_DIAGNOSTIC_POSITIONS.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
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>
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>
* 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>
* 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>
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>
Without the same-type scalar cases, the macro body has no use for it, and
JSON_IMPLEMENT_SCALAR_CASES is now used only by JSON_IMPLEMENT_SCALAR_FAST.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
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>
* 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>
* 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>
* 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>
* Make basic_json::insert() provide its documented strong exception guarantee (#5986)
A failed allocation while the new elements were copied left the value
changed, and with JSON_DIAGNOSTICS stale parent pointers behind. The
extra work now happens almost only on the failure path:
- Array insert(pos, cnt, val) and insert(pos, first, last) append the
copies at the end and rotate them into place. If a copy throws, the
appended elements are erased again (noexcept) and the parents are set.
Moving a basic_json cannot throw, so reallocation is safe. This is no
slower than vector::insert (faster for numbers), needs no temporary
array, and keeps the elements that libstdc++ lost on reallocation.
- Array insert(pos, val) copies a non-scalar value first and inserts it
by move, except at the end, where vector::insert is strong. Scalars
keep the direct path.
- The object range insert(first, last) into an empty object uses the
container's own range insertion and clears the object on an exception.
Into a non-empty object it inserts member by member and logs one bit
per source member (a new member is detected by the size change; no
allocation for the first 256 members); on an exception the members
added are erased by walking the source range. No assumption that
key_type is string_t.
- The parents are set when a failed insertion is undone.
The regression test fails every allocation of every insert() overload in
turn, for json and ordered_json, and checks the value and its parents.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Fix clang-tidy and -Wnrvo findings in insert rollback helpers
Declare the rollback helpers non-movable, replace the nested conditional
and C array in object_insert_rollback, silence the intentional copy in the
allocator test, and avoid the missed NRVO in the test factory lambda.
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>
* insert(): strong guarantee for single elements, basic for the rest
Rework of the previous two commits, following the discussion in #5996:
the standard containers give the strong guarantee only for a single
element (std::vector: at the end, or if the exception does not come from
copying T; std::map: single-element insert), and copying a basic_json
allocates. Rebuilding a rollback for the count, range and object-range
overloads on top of array_t/object_t made the code verbose and slower.
- insert(pos, const basic_json&): at end() forward as before (the
standard covers it); elsewhere copy first and insert by move, as
libstdc++ does internally (libc++ shifts the tail before copying).
- insert_iterator() and object insert(first, last) set the parents in a
scope guard, so a failed insertion leaves a valid value with
JSON_DIAGNOSTICS too (the next assert_invariant() aborted before).
- Docs: strong guarantee for (1), basic guarantee for (2)-(5); the
argument checks throw before anything is changed.
- Test: allocation-failure sweep checks the strong guarantee for (1) and
validity, type and parents for the other overloads.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* insert(): document the exception safety of overloads 2 to 5 once
The four basic-guarantee statements were identical up to array/object.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* insert(): simplify the wording of the basic guarantee
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>
* 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>
* Do not construct the base class when destroying a container (#5995)
json_value::destroy_container() and destroy_walk() used default-
constructed basic_json values as stand-ins, which construct a
CustomBaseClass that belongs to no value. A base class whose default
constructor allocates made the noexcept destructor allocate again, and
terminate if that allocation failed, which #5762 set out to prevent.
Use data (type and value, no base class) as the stand-in instead, and
pass the children's m_data to the walk helpers.
Add a test with a counting base class: destroying a value constructs no
base object and destroys exactly one per value, also for values nested
deeper than the recursion depth limit.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Release the test value with = nullptr instead of reset()
clang-tidy (readability-ambiguous-smartptr-reset-call) rejects j.reset()
because the pointee inherits a reset() from counting_base.
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>
* Use std::swap for the container stand-in in destroy_container
The unqualified call after `using std::swap` would let a user-provided
swap(json_value&, json_value&) intercept the destruction path. Call
std::swap directly.
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>
* 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>
* 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>
GitHub is moving the ubuntu-latest label from Ubuntu 24.04 to 26.04
between October 19 and November 19, 2026 (actions/runner-images#14748).
Pin every ubuntu-latest job to ubuntu-26.04 so the switch does not
change the toolchain under our jobs, and so the behaviour does not
depend on when GitHub reaches our runs.
Jobs pinned to ubuntu-24.04 and ubuntu-24.04-arm are unchanged.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
readability-math-missing-parentheses in unit-json_view_builder.cpp (#5974)
and performance-inefficient-string-concatenation in
unit-json_view_positions.cpp.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* 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>
* 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>
* 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>
* 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>
#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>
A json_view or json_document decodes a macro-defined struct directly and looks
the members up by their decoded keys. Only plain keys were covered so far.
The new section decodes structs defined with NLOHMANN_DEFINE_TYPE_INTRUSIVE,
..._WITH_DEFAULT and ..._WITH_NAMES from documents whose keys contain escape
sequences, and compares the result with the conversion of the materialized
value. It also pins the difference for a duplicate key written once plain and
once escaped (the view takes the first member, the materialized value keeps
the last one), and that an escaped backslash is part of the decoded key.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
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>
#5919 replaced the bool template parameter Editable of basic_json_view by
view_mode Mode and defined is_editable from Mode. #5890 was written before
that and added a second is_editable = Editable to the private section, which
no longer compiles ("duplicate member", "undeclared identifier Editable"). It
broke every job that builds the json_view tests (macOS, MSVC, clang-cl,
clang on Windows, the C++20 module job, CodeQL).
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
- bench_view: add "(editable)" rows for json_editable_document and a
parse+dump workload, so the cost of lazy float conversion shows next to the
parse row (the traverse workload already includes the parse). Check that
all engines' dumps agree where outputs are comparable.
- compare.py: add --aligned, which also builds and runs with aligned code and
reports both tables, so code-layout artifacts become visible. Off by
default; the default output is unchanged. Not run end to end yet.
- README: say which engines are like-for-like peers (yyjson, simdjson DOM) and
which are mutable reference points (Boost.JSON, json::parse, the editable
json_view); explain the lazy float conversion and the eager prototype that
was measured and dropped.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* 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>
* 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>
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>
Constructing a std::string from uint8_t iterators converts values >= 0x80
implicitly to char, which ci_test_clang_sanitizer rejects. Convert each
byte with an explicit static_cast.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Document the contract of object keys passed to json_sax::key and key callbacks
Describe what the name passed to json_sax::key and to a parser callback
for parse_event_t::key holds when parsing JSON text: escapes are decoded
to UTF-8, different spellings of a name yield identical strings, the name
is validated before the call (invalid escapes or UTF-8 give a parse error
and no key event), no normalization or case conversion is applied, the
event precedes the ':' check, and duplicate names are reported once per
occurrence. Also note that sax_parse passes binary-format keys unchanged.
See discussion #5955.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Add a test for the object key contract and correct the BON8 note
Pin the guarantees documented for json_sax::key and the key event of
parser callbacks: decoded names, validation before delivery, delivery
before the colon, one event per repeated name, and the binary formats.
BON8 rejects ill-formed UTF-8 in a name even with sax_parse, so the
note no longer lists it with the formats that pass bytes through.
See discussion #5955.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Fix the GCC build of the object key contract test
GCC 11 in C++11 mode rejects a default argument on a lambda parameter
(-Wc++14-extensions) and ignores a static_cast<void> on the
warn_unused_result of parse(). Pass the input format explicitly and bind
the parse result to a variable.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Add version history for the object key contract
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
---------
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
Split the combined has_save/has_load static_asserts so clang-tidy no
longer sees both sides of && as equivalent (develop ci_clang_tidy failure).
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
VS 2015 does not accept std::string::npos in a constant expression (C2131),
and the constant is only used at run time.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* 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>
* 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>
MSVC 2015 treats two function templates that differ only in a decltype
return type as a redefinition (C2995), which breaks all three Visual
Studio 2015 jobs on AppVeyor. Overload on the view's mode in the
parameter type instead; template argument deduction ignores the
read-only-to-editable conversion, so each view still selects the
overload of its own mode.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Fix clang-tidy findings in unit-json_view_from_json.cpp
Silence misc-use-internal-linkage on the macro-generated ADL functions,
reconcile -Weffc++ with readability-redundant-member-init, use auto for
get<T>() initializers, and use value() on the optional access.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Satisfy bugprone-unchecked-optional-access in unit-json_view_from_json.cpp
clang-tidy 22 also flags value(); check has_value() in the same expression.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
---------
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
The test relies on a copied fifo_map restarting its timestamps. Copying a
basic_json does that only on the recursive path; with JSON_NO_THREAD_LOCAL
the copy is built member by member and keeps correct timestamps, so the
premise was missing and the test failed (ci_test_no_thread_local, MinGW
clang). Copy the object_t explicitly to create the state on every path.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
- unit-bson: initialize the SAX recorder's member (-Weffc++)
- unit-json_patch: build the reference document independently instead of
copying it (performance-unnecessary-copy-initialization)
- unit-json_view_builder: use node_kind::link instead of an out-of-range
enum cast (clang-analyzer-optin.core.EnumCastOutOfRange)
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
Spell out that numbers comparing equal produce no operation even if one is
zero and the other negative zero, in diff.md and features/json_patch.md.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* 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>
* docs: new design for the documentation site
Apply the brand to the Material for MkDocs site: Inter and JetBrains Mono
served by the site (upright and real italic), brand colours, blue header band
with the syntax pattern, wordmark in the header, new home page (hero, cards,
animated feature tour), 404 page, polish for tabs, search, footer, focus
rings, tables and code blocks, and theme features (code copy, previous/next
footer, TOC follow, search suggestions).
Draw the number railroad diagram, the parser callback events and the iterator
illustrations as inline SVGs that follow the light and dark scheme. The
generator scripts are in docs/mkdocs/scripts/figures; the feature slideshow
(json-light.svg, json-dark.svg, replacing json.gif on the home page) is built
by docs/mkdocs/scripts/slideshow. Decision nodes in five flowcharts become
hexagons, which need far less room.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* docs: add figures, table captions and a macro chooser
- Figures with numbered captions: SAX stepper, json_view layout and edit
stepper, exception map, JSON pointer and patch walkers, QA pipeline,
scaling and binary size charts, roadmap lanes, release timeline,
integration decision tree and namespace builder
- Table captions (nj-table-caption) on 9 pages
- Compile times: modules and PCH charts, filesystem section, re-measured
Figure 1, links between features/modules.md and compile_times.md
- Interactive macro chooser for features/arbitrary_types.md
- Link check: exclude URLs that answer the plugin with 400/401/419 or are
dead (customers.md)
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* docs: macro chooser generates adl_serializer for non-default-constructible types
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* docs: cross-link concept pages and API pages in See also sections
Add See also links in both directions between the concept pages (features,
home, integration) and the API pages, write API links in code font, give every
entry a comment after a dash, and show the callback event figure on the parser
callbacks page.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* docs: address review comments on the new design
- Home: add a "Latest release" button
- Sponsors: update the list and group it by tier
- Features: list all feature pages on the index page
- Releases: add highlights per release, link the 4.0 roadmap, add the first commit to the timeline
- Exceptions: prefix all example messages with the exception name
- API: no code font for format names in the See also links of the to_/from_ pages
- Merge Patch: show the document before, the patch, and the result
- Replace "--" with typographic dashes, mark external links with an icon, center Mermaid diagrams
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
---------
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* json_view: pointer tokens that cannot be array indices create objects
editable_document::set() chose an array for a null parent whenever the
token consisted of digits, so "01" threw parse_error.106 and the empty
token threw, while basic_json::operator[](json_pointer) has created an
object for such tokens since #5358. This broke
unit-json_view_edit_values on develop. Use the same RFC 6901 array index
test as basic_json.
Also re-indent the unflatten test that the astyle check flagged.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Fix the other red jobs on develop
- unit-bson: initialize recorder::events in its declaration (-Weffc++)
- unit-json_view_from_json: suppress -Wexit-time-destructors for the
serialize-enum tables and -Wfloat-equal for same()
- unit-pointer_access: @infer-ignore NULLPTR_DEREFERENCE for the
dereferences after get_ptr() that Infer reports
- json_view.hpp: IWYU no_include for the detail headers that the view
code uses through nlohmann/json.hpp
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Fix GCC warnings in the json_view from_json test
GCC (-Weffc++, -Wfloat-equal) rejected unit-json_view_from_json.cpp
(ci_test_standards_gcc (20)): initialize the members of shape and
with_names, and suppress -Wfloat-equal for GCC like for clang.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
---------
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
- 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
537 changed files with 39561 additions and 6369 deletions
- The class contains a copy of [Hedley](https://nemequ.github.io/hedley/) from Evan Nemerson which is licensed as [CC0-1.0](https://creativecommons.org/publicdomain/zero/1.0/).
- The class contains parts of [Google Abseil](https://github.com/abseil/abseil-cpp) which is licensed under the [Apache 2.0 License](https://opensource.org/licenses/Apache-2.0).
- The view's parser (`<nlohmann/json_view.hpp>`) contains techniques and code adapted from [yyjson](https://github.com/ibireme/yyjson) by YaoYuan, which is licensed under the [MIT License](https://opensource.org/licenses/MIT) (see above): table-driven decoding of `\u` escapes and fixed-offset unrolled checks.
COMMAND${GENHTML_TOOL}--title"JSON for Modern C++"--legend--demangle-cpp--output-directoryhtml--show-details--branch-coverage--ignore-errorsinconsistentjson.info.filtered.noexcept
Overload (4) also accepts a [`json_pointer`](../json_pointer/index.md) whose template argument is a `basic_json`
@@ -274,13 +290,15 @@ Strong exception safety: if an exception occurs, the original value stays intact
## See also
- documentation on [unchecked access](../../features/element_access/unchecked_access.md)
- documentation on [runtime assertions](../../features/assertions.md)
- see [`at`](at.md) for access by reference with range checking
- see [`value`](value.md) for access with default value
- [basic_json_view::operator[]](../basic_json_view/operator%5B%5D.md) - the same access on a zero-copy view (a duplicate
- [Unchecked access](../../features/element_access/unchecked_access.md) - element access without range checking
- [Runtime assertions](../../features/assertions.md) - assertions guarding against undefined behavior
- [`at`](at.md) - access by reference with range checking
- [`value`](value.md) - access with default value
- [`basic_json_view::operator[]`](../basic_json_view/operator%5B%5D.md) - the same access on a zero-copy view (a duplicate
key resolves to the first member, whereas `parse()` keeps the last; a missing key gives a discarded view instead of
undefined behavior)
- [Element Access](../../features/element_access/index.md) - overview of all ways to access elements
- [JSON Pointer](../../features/json_pointer.md) - access nested values with a pointer
## Version history
@@ -294,4 +312,6 @@ Strong exception safety: if an exception occurs, the original value stays intact
4. Added in version 2.0.0. A missing array index in the const version is guarded by a runtime assertion since
version 3.13.0. Throws [`parse_error.109`](../../home/exceptions.md#jsonexceptionparse_error109) instead of
[`out_of_range.404`](../../home/exceptions.md#jsonexceptionout_of_range404) for a one-character array index that is not
a digit (e.g., `/x`) in version 3.13.0, as it already did for longer ones.
a digit (e.g., `/x`) in version 3.13.0, as it already did for longer ones. Fixed in version 3.13.0 to leave the value
unchanged if the non-const version throws (strong exception safety, as documented); before, values created for earlier
reference tokens of `ptr` were kept.
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