Commit Graph
193 Commits
Author SHA1 Message Date
Niels Lohmann a03ddc4a80 Document that editable documents refuse invalid UTF-8 copied from a loaded image
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-17 14:22:13 +02:00
Niels Lohmann a8b3efd558 Check each distinct string and float range once in the full image check
The full check scanned the contents of every string node and every float token over its own range, so many nodes pointing to one large range made load() quadratic. The structural walk now only collects the ranges; after it, each kind is sorted and checked once per distinct range. Ranges of one kind that overlap without being identical are rejected, as save() never writes them (nodes that share a value share the whole range). The cost is linear in the size of the image plus sorting the ranges.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-17 14:22:08 +02:00
Niels Lohmann a970bf315d Fix MSVC errors in image test and add image_check doc anchor
Move the raw string literal out of the CHECK macro (MSVC preprocessor),
cast 64-bit header fields to std::size_t (C4244 on 32-bit), and give the
image_check section in load.md a real anchor for the mkdocs strict build.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-17 14:22:07 +02:00
Niels Lohmann 1089416136 Add images of json_documents: save() and load()
An image is a document stored so that loading it needs no
parsing: save() writes the node index, the text and the decoded
strings; the static load() reads an image written by save().

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

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

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

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

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

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-17 14:22:06 +02:00
Niels Lohmann 5a09b7bd14 Assign the first member when set() meets duplicate keys again
Lookups find the first member of a repeated key again, so set(object, key,
value) assigns that member (keeping the key where it is) and drops the
others, as documented before, and a view taken from object[key] shows the
new value. This undoes the code and documentation changes of 5cbb8e6d6.
Lookups in edited objects (navigation of editable documents) stop at the
first match, like those of parsed objects.

The tests that commit added expect the first member from lookups now. In the
seeded differential test, the documents with repeated keys repeat them after
the real members; the reference holds the first members, which the edits
address and the lookups are compared with, while materialize() is compared
with what parse() makes of the document's dump.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-17 14:21:57 +02:00
Niels Lohmann 7717d3d1ff Assign the member that lookups find when set() meets duplicate keys
An editable document reads the last member of a repeated key (as the
read-only document does), but set(object, key, value) assigned the first
one: a view taken from object[key] before the call did not show the new
value. It now assigns the last member's value, keeps the key at the
position of its first occurrence (where materialize() puts it), and drops
the other members.

The seeded differential test now also edits documents whose objects
repeat keys and compares every lookup (operator[], at, find, value,
contains, count, and JSON pointers) with the parsed basic_json value.
A targeted test covers duplicates before and after edits that move the
object, in large objects with an index, in moved arrays, and in values
copied from other documents.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-17 14:21:56 +02:00
Niels Lohmann 18d1bad340 Replace a container by a scalar in constant time once it is linked
Replacing an array or object that spans several nodes by a scalar looks
up its parent from the root (find_parent), which is linear in the size
of the document: setting every element of a 20,000 element array took
more than half a second. The parent only has to switch to links once;
afterward the extent of the replaced value no longer matters. Nodes that
an entry of a moved sequence links to are now marked (node_flags::linked),
and assign() skips the lookup for them.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-17 14:21:55 +02:00
Niels Lohmann c2d239f17b Set a null value below a pointer as basic_json does
set(json_pointer, value) turned a null parent into an object for every
last reference token, so "/a/0" and "/a/-" below {"a":null} made
{"a":{"0":1}}, where basic_json's operator[](json_pointer) makes an
array. A null parent now becomes an array for "-" and for digit tokens
(filled with nulls up to the index) and an object otherwise. An invalid
index is reported before the parent changes.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-17 14:21:54 +02:00
Niels Lohmann fed24de2cb Add editable json_documents: set, push_back, insert, and erase
basic_json_document gets a second template parameter, Editable
(false by default), plus the aliases json_editable_document,
json_editable_view, ordered_json_editable_document and
ordered_json_editable_view.

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

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

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

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

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-17 14:21:49 +02:00
Niels Lohmann 343f1f368c Keep the first of duplicate keys in the object hash index again
Lookups in objects with 128 members or more return the first member of a
repeated key again, like the linear search of smaller objects. This undoes
the code change of a69542046; its test now expects the first member from
lookups (with and without a table) and the last value from materialize()
and basic_json::parse().

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-17 14:21:39 +02:00
Niels Lohmann 1fc3153ea7 Keep the last of duplicate keys in the object hash index
Lookups in objects with 128 members or more now return the last member of
a repeated key, like the linear search of smaller objects and like
materialize() and basic_json::parse(). build_object_index let the first
occurrence win, so the same text gave different results depending on the
size of the object.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-17 14:21:38 +02:00
Niels Lohmann 750750953d Scan json_view strings with SIMD and index large objects
Speed up json_view's parser with SIMD scanning and a hash table
for large objects.

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

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

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

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

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-17 14:21:32 +02:00
Niels Lohmann 578ba8035a Document and test first-wins lookups next to dump() and ==
dump() writes every member and == resolves duplicate keys as parse()
does, whereas lookups find the first member of a duplicate key.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-17 14:21:26 +02:00
Niels Lohmann 2b07adf010 Add dump() and comparisons to json_view
Add basic_json_view::dump() and the comparison operators, and read
floats from the parser's digit layout instead of rescanning the
token.

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

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

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

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-17 14:21:22 +02:00
Niels Lohmann 8889a2a3b9 Return the first member of duplicate keys from lookups again
Looking up the last member of a duplicate key cannot stop at a match, so
every lookup scanned the whole object (1.6 to 3.4 times slower for small
objects). operator[](key), at, find, value, contains, count, and JSON
pointer resolution return the first member again, as yyjson and simdjson
do; materialize() and get<map>() keep the last value, as parse().

The documentation says so in the feature page and on each lookup page,
and explains how to get the value parse() would give. The integer index
templates and the discarded chaining of operator[] stay.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-17 14:21:14 +02:00
Niels Lohmann acd6c7613b Test discarded views with is_discarded() in the operator[] docs and examples
The explicit conversion to bool of basic_json_view is gone.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-17 14:21:13 +02:00
Niels Lohmann f286eb4f5b Make view lookups last-wins and chained access safe
* Lookups (operator[], at, find, contains, count, value, JSON pointers)
  return the last member of a duplicate key, as materialize() and
  parse() keep it.
* operator[] on a discarded view returns a discarded view instead of
  throwing, so v["a"]["b"] is safe for a missing "a".
* operator[] and at() take any integer type (not only int and size_t),
  fixing ambiguous calls with unsigned, long, std::int64_t, ...
* Fix the operator[] documentation, which claimed a discarded view for
  a type mismatch where type_error.305 is thrown.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-17 14:21:11 +02:00
Niels Lohmann 071a0dfbee Add element access, iteration, values, and JSON pointers to json_view
Give basic_json_view the read-only access functions of basic_json:
operator[] and at() with keys and indices, front()/back(), find(),
contains(), count(), begin()/end() and cbegin()/cend(), items()
with structured bindings from C++17 on, and type_name().

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

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

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

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-17 14:21:10 +02:00
Niels Lohmann 6d3f0dae96 Apply the review's wording fixes to the json_view documentation
- Copying is disabled because of its cost, not because of two documents
  borrowing the same buffer; the unique_ptr follows from move-only.
- Inputs: streams, FILE*, and wide characters (strings, arrays, pointers)
  are all supported and owned; point to parse_copy() for owned copies.
- The error replay only runs for failing input, builds no values, and is
  skipped with allow_exceptions = false.
- read() writes copied inputs into the previous owned copy.
- Views can dangle like std::string_view, and why there is no
  shared/weak pointer design.
- The 4 GiB limit (16-byte nodes, 16-byte scanner steps), streams being
  read to the end first, which macros apply, why materialize() has no
  source positions, and wording nits (accept() vs basic_json::accept(),
  is_binary, is_discarded, see-also lists, size table, "back into").

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-17 08:30:46 +02:00
Niels Lohmann 037d245df8 State the exact input size limit of json_document
The check rejects inputs of 0xFFFFFFF0 bytes or more, but the exception
message and the documentation said 4 GiB. Name the limit once
(max_input_size), and state 4 GiB minus 16 bytes in the message and the
documentation. Test the limit with a container that only claims the size.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-17 08:30:34 +02:00
Niels Lohmann 19c845aa82 Delete json_document::root() on temporary documents
auto v = json_document::parse(text).root() compiled and left the view
dangling. Delete the overload for rvalue documents, take a named document
in the tests, and document the lifetime rule.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-17 08:30:32 +02:00
Niels Lohmann a80897e895 Remove the conversion to bool from json_view
explicit operator bool meant "refers to a value", which silently differs
from what a basic_json converts to. Use !v.is_discarded() instead.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-17 08:30:31 +02:00
Niels Lohmann ab1cc82bd1 Copy const rvalue strings and document the accepted inputs
json_document::parse(std::move(const_string)) failed to compile with
"no matching read_kind": only a non-const rvalue std::string can be moved
from. Treat a const rvalue as a copied byte container.

parse() does not accept everything BasicJsonType::parse() does: a FILE*
and pointers to or arrays of wide characters are rejected at compile time.
List the supported inputs instead.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-17 08:30:30 +02:00
Niels Lohmann 302ffe5c13 Reject integer lengths in json_document::parse
parse(ptr, len) compiled: len converted to allow_exceptions, and ptr was
read as a C string, past the end of a buffer without a terminating NUL.
Delete the overloads of parse, parse_copy, accept, and read that take an
integer other than bool where the flags are expected.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-17 08:30:29 +02:00
Niels Lohmann 481a9a216f Add json_document and json_view: node index, parser, and document
Add json_document and json_view, a read-only, zero-copy index of a
JSON text, as the first public slice of the zero-copy view (#5295).

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

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

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

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

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

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-17 08:30:27 +02:00
Niels Lohmann ce28c722bc Allow the same type for number_integer_t and number_unsigned_t (#5815)
* Allow the same type for number_integer_t and number_unsigned_t

basic_json did not compile with NumberUnsignedType == NumberIntegerType
because overloads on both types collided. Such a basic_json now stores
every integer as number_integer: the colliding overloads take a
placeholder type, unsigned C++ integers are converted to number_integer_t,
and value_t::number_unsigned maps to number_integer.

Also fixes two problems this configuration would hit: the unsigned
integer parser accepted values that wrap around to negative numbers, and
dump() overflowed when computing the absolute value of the minimum.

A repeated NumberFloatType gets a static_assert.

Refs #2573

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

* Use json::with_integers_t in the test and the docs

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

* ✅ skip patch test on GCC 5 to avoid internal compiler error

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

* Fix CI: name the unsigned overload type through template parameters

basic_json used number_unsigned_overload_t<basic_json> while the class was
still incomplete. MSVC rejected it as a recursive alias declaration and GCC
4.9, 5 and 7 crashed with an internal compiler error. basic_json now uses
number_unsigned_overload_type<NumberIntegerType, NumberUnsignedType>, which
also makes the GCC 5 workaround in the patch test unnecessary.

Infer reported a null dereference for the number_unsigned case in
from_json, which cannot happen for a basic_json whose number_unsigned_t is
number_integer_t; assert it.

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

* Address review: conjunction/negation trait, astyle-friendly alias, docs table order

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

---------

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-15 20:04:42 +02:00
Niels Lohmann ca7740fef2 Move elements when converting rvalue containers to JSON (#5837)
* Move elements when converting rvalue containers to JSON

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

* Simplify the rvalue to_json traits

Use negation<disjunction<...>> instead of a conjunction of negations and
keep the template argument lists compact (astyle only keeps the spaced
'< ... >' form when it is written that way).

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

---------

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-15 20:01:20 +02:00
Niels Lohmann 4e294f4b18 Clarify that double is only the default floating-point type in the docs (#5830)
Follow-up to review comments on #5825: number_float_t uses double
precision only by default, and the stated limits apply to double.
Also say "default type for X_t" instead of "default value for X_t".

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-14 18:28:49 +02:00
Niels Lohmann ccc005c012 Fix contradictions between the documentation, the README, and the library (#5825)
- Discarded values: the legacy macro only changes <= and >=; != is true by default
- Out-of-range numbers are rejected while parsing, not stored as NaN
- merge_diff round trip: point to the ordered_json caveat
- ensure_ascii example shows the escaped output
- out_of_range.405 is thrown for "remove"/"move" on the root, not "add"
- CBOR stores binary subtypes as tags
- Integer/float comparison uses exact values, not conversion
- diff, flatten, and the binary writers are depth-bounded
- FAQ: max_digits10 for serialization, trailing commas are supported
- out_of_range.407 is still thrown by to_bon8
- FetchContent_MakeAvailable needs CMake 3.14
- json_fwd.hpp contents, operator< link, RFC 7396 for merge patch
- README: dump() wording, merge_diff, MSYS2/build2, patch comment typos,
  operator[] link, embedded CMake example aligned with the docs

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-14 17:40:55 +02:00
Niels Lohmann 91a7a94cc6 Write doubles with the shortest digits (Żmij), digits in registers (#5634)
* Write doubles with the shortest digits (Żmij), digits in registers

Write doubles with the conversion of Zmij by Victor Zverovich (MIT),
ported to C++11 (detail/conversions/zmij.hpp). It finds the
shortest decimal that reads back as the same double, and the
closest one if there are several. Grisu2, used until now, is fast
but not always shortest: it sometimes writes a 17th digit where 16
suffice, or a last digit that is not the closest. The layout is
unchanged (1.5, 100.0, 1e+100, -0.0); float keeps Grisu2.

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

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

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

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

* Fix CI findings in the Zmij writer and its tests

- bit_ops.hpp: include macro_scope.hpp (JSON_HEDLEY_ALWAYS_INLINE); fixes IWYU
- to_chars.hpp: C4100 for the unused parameter in release builds, clang-tidy
  sign comparison, cpplint runtime/int, GCC -Wstrict-overflow (unsigned abs)
- unit-to_chars.cpp: parse with the library instead of strtod (MinGW's strtod
  rounds some 16/17 digit inputs wrongly); no floating-point std::to_chars
  with icpc

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

* Select the Zmij conversion by a trait, not by the double overload

The non-template overloads for double asserted binary64 doubles wherever json.hpp was included, so the library no longer compiled where double is not IEEE 754 binary64 (AVR, -fshort-double). A trait now picks Zmij for any binary64 type, including a long double of that format (MSVC, Apple Arm), and Grisu2 for the others. Remove the unused write_short_decimal, powers_of_ten_16, zmij::decimal, zmij::to_decimal, and shortest_digits(double).

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

* Credit Zmij's authors in to_chars.hpp, the README, and the license page

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

* Silence MSVC C4127 for a platform-constant check in the to_chars test

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

* Regenerate the amalgamated headers

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

---------

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-14 17:38:37 +02:00
Niels Lohmann 5b4c8f9b00 Speed up the lexer: own float parser, string scan, and \u table (#5738)
* Speed up the lexer: own float parser, string scan, and \u table

Give the library its own correctly rounded float converter for
binary32 and binary64 (IEEE 754), and speed up the lexer's string
and escape scanning.

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

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

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

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

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

* Fix CI warnings in own float parser

- pow5_table.hpp: pow5_128_largest_power was unused in this branch's
  own code (GCC -Werror=unused-const-variable); tie it to the table
  size with a static_assert instead of removing it, since a later
  branch in the stack (json-view/23-zmij) uses it.
- number_parse.hpp: rename the local variable `copy` to `buffer` to
  satisfy cpplint's build/include_what_you_use check.
- unit-class_lexer.cpp: extend the NOLINT list on the seeded mt19937
  with bugprone-random-generator-seed, and parenthesize
  `8 * sizeof(Bits) - 1` for clang-tidy.

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

* Load string scan words with memcpy and use MSVC bit-scan intrinsics

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

* Reword float conversion notes for the string type and number_float_t docs

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

* Fix clang-tidy 22 findings in unit-class_lexer.cpp

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

* Mark the unsigned long of the MSVC bit scans for cpplint

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

* Regenerate the amalgamated headers

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

* Drop the position updates in the bulk \u path, which #5809 made unused

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

* Address review: std::any_of in has_nonzero_digit, comment punctuation

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

* Use data() instead of c_str() in the multi-byte decimal point path

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

---------

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-14 17:38:36 +02:00
Niels Lohmann 7461a199b5 Drop the class wrapper from the C++20 comparison operator signatures in the docs (#5814)
* Drop the class wrapper from the C++20 comparison operator signatures in the docs

The signature boxes of operator<=> and the C++20 half of operator== wrapped
the member declarations in an incomplete "class basic_json { ... };". The
trailing const already marks them as members, and no other page uses such a
wrapper.

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

* Drop the class wrapper from the json_pointer comparison signatures too

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

---------

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-13 20:06:14 +02:00
satelliteprogrammer 40a62947d3 support JSON Merge Patch (RFC 7396) diff creation (#4965)
* support JSON Merge Patch (RFC 7396) diff creation

The JSON merge patch document format describes the set of modifications
to a resource's content, that more closely mimics the syntax of the
resource being modified.

However, and in contrast to JSON Patch (RFC 6902), a JSON Merge Patch
cannot express certain modifications, e.g., changing an array element
at a specific index, or setting a specific object value to null.
The null value in a JSON Merge Patch is used to remove the key from the
object.

The diff algorithm is not part of the RFC 7396, but it was tested
against all examples provided, plus additional cases on how null values
are handled.

Signed-off-by: Luís Murta <luis@murta.dev>

* improve algorithm efficiency

Signed-off-by: Luís Murta <luis@murta.dev>

* fix inconsistent nulls and empty arrays

Also add CHECKs for the patch, documentation and run `make amalgamate`.

Signed-off-by: Luís Murta <luis@murta.dev>

* documentation cleanups

Signed-off-by: Luís Murta <luis@murta.dev>

* add an iterative fallback to merge_diff

Bound the recursion depth like diff() and merge_patch(), and test values
nested past the bound.

Signed-off-by: Luís Murta <luis@murta.dev>

* address the remaining review comments

Signed-off-by: Luís Murta <luis@murta.dev>

* move multi-line raw strings out of CHECK macros

GCC 4.8/5, ICPC and NVHPC mis-tokenize multi-line raw string literals
inside macro arguments, breaking the build or the parsed JSON.

Signed-off-by: Luís Murta <luis@murta.dev>

---------

Signed-off-by: Luís Murta <luis@murta.dev>
2026-10-12 09:33:43 +02:00
Niels Lohmann eb8899a29c Restore v3.12.0 support for custom object key types (#5795)
* Restore v3.12.0 support for custom object key types

Custom object_t types whose key_type is not string_t compiled with
v3.12.0 for several APIs that unreleased changes broke:

- to_bson failed for every custom key type (#5553 kept a const string_t*
  to the key); the nested entry's header is now written where the entry
  is found.
- Copying deep values (and parse, merge_patch, update, insert) required
  operator== on keys (#5389); keys without one are now paired via find().
- to_cbor/to_msgpack required an implicit conversion to string_t (#5746,
  #5328); keys without one go through a temporary basic_json again.
- at() required a conversion to string_t for its error message (#5727);
  other keys are passed to concat() unchanged again.

The new unit-custom-object-key-type.cpp covers five key types with
different capabilities.

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

* Use the with_object_t alias for the custom object key test types

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

* Avoid floating-point equality in custom key type test

GCC with -Werror=float-equal rejects comparing the double value with ==.

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

* Write the head of nested BSON elements in one helper

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

* Suppress bugprone-return-const-ref-from-parameter in key_for_message

The reference is only passed to concat() within the full-expression that
holds the key, like the similar helpers in binary_writer.hpp.

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

* Make the value of the custom test key types private

clang-tidy (cppcoreguidelines-non-private-member-variables-in-classes)
rejects the protected member; the derived key types use a protected
accessor instead.

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

* Pass keys with data() and size() unchanged into the at() miss message

key_for_message() converted every key that string_t can be constructed
from, so a miss on a string_t or string_view key copied it before
concat() copied it again. Keys that concat() can append through data()
and size() are now passed through; only other keys (string literals,
key types that just convert to string_t) are converted.

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

---------

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-11 08:24:31 +02:00
Niels Lohmann 11ef352511 Point users to update(…, true), JSON Pointer defaults, and built-in std::optional (#5804)
A code search of client code found many hand-written versions of
functionality the library already has: recursive object merges
(update(j, true) since 3.10.5), dotted-path getters (value() and
contains() with a JSON Pointer), get_or helpers (value() throws for a
member that is present but null), and adl_serializer specializations
for std::optional (supported since 3.12.0).

- modifying_values.md: describe both modes of update(), add a
  defaults + user settings recipe, and stop recommending Merge Patch
  for recursive merges.
- merge_patch.md: note that null deletes keys, so a merge patch is not
  a general deep merge; link update().
- default_value.md: add "Nested values" (value/contains with a JSON
  Pointer, building a pointer from a dotted path with operator/=) and
  a warning that null and mistyped members are not missing.
- value.md: note that a null member is converted, not replaced by the
  default.
- json_pointer.md: link value/contains/at with JSON Pointers.
- arbitrary_types.md: note that std::optional needs no serializer.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-11 08:22:10 +02:00
Niels Lohmann 74a03dec84 Throw type_error.321 for discarded values in to_bon8 (#5802)
write_bon8_value silently skipped discarded values, but the array/object
count marker still counted them, so [1, discarded] produced 82 91: a marker
announcing two elements followed by one. Throw type_error.321 like the other
binary writers do, at any nesting level.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-11 08:22:00 +02:00
Niels Lohmann 6197341a21 Clean up non-code files (#5801)
* Clean up README, contribution guide, and repository metadata

- REUSE.toml: fix the Hedley path and SPDX id (CC0-1.0), mark the docset
  icons as the public-domain JSON logo
- CITATION.cff: v3.12.0 was released on 2025-04-11
- FILES.md: list all workflows, describe the Meson option defaults
- README: ctest -LE, table of contents, typos, stale Android/MinGW advice,
  moved links, merge duplicate Thanks entries, list the analysis tools
  used in CI
- CONTRIBUTING: iterative parser, json_literals.hpp is generated, links
- .gitignore: backups and release outputs; .gitattributes: mark
  generated files
- labeler: label other build systems and .github documentation
- MODULE.bazel: add the module version

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

* Clean up CI, CMake, Makefile, and Bazel files

- CMakeLists.txt: avoid VERSION_GREATER_EQUAL, which CMake < 3.7 lacks
- ci.cmake: test JSON_DisableTupleReferenceConversion in ci_cmake_flags,
  remove unused variables and unreachable per-compiler targets, look up
  Clang tools consistently, forward CMAKE_CXX_FLAGS to ci_module_cpp20,
  format json_literals.hpp and remove backups in ci_test_amalgamation
- BUILD.bazel: add json_literals.hpp to the single-header target
- workflows: format json_literals.hpp before copying it, drop the obsolete
  natvis --version plumbing, name natvis and macro_builder in failure
  messages, drop the duplicate amalgamation job, install Valgrind only
  where needed, republish docs on version bumps, fix stale names
- Makefile: complete .PHONY and help, check-amalgamation always restores
  the checked-in files, natvis uses its own venv, macro_builder_check
  installs astyle, clean removes the fuzzer binaries
- remove tools/amalgamate/config_json_view.json (json_view.hpp is not on
  develop yet)

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

* Fix inaccuracies in the documentation

- version history: json_base_class_t (3.11.3), JSON_HAS_CPP_11 (3.10.0),
  JSON_HAS_RANGES exclusions, define-type macros, ABI tags
- releases: 3.12.0 raised the minimum CMake version
- from_*: the (ptr, len) overloads are deleted, not removed, in 4.0.0
- contains/count/find: document the deleted integral overloads
- add JSON_HAS_RANGE_VIEW_CONVERSION and list the JSON_HAS_* macros in
  the macro overview
- mention BON8 and error_handler where binary formats are listed
- broken links, outdated URLs, warning count, Hunter v0.26.12
- copy_markdown_source hook: expand snippets in the Markdown copies

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

* Pass /EHsc to the Windows C++20 module build

ci_module_cpp20 now forwards CMAKE_CXX_FLAGS to the module build. The
Windows workflow sets CMAKE_CXX_FLAGS, which replaces CMake's MSVC
defaults including /EHsc, so <chrono> failed with C4530 under /WX.

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

---------

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-11 08:21:51 +02:00
Niels Lohmann 2cca04ae6f Report one-character non-numeric array indices like longer ones (#5800)
* Report one-character non-numeric array indices like longer ones

A JSON pointer reference token that is not a number but has only one
character (e.g. "/a/x") was reported as out_of_range.404 ("unresolved
reference token"), because the "is not a number" check only ran for
tokens longer than one character; "/a/xy" got parse_error.109. Both now
throw parse_error.109. "-" and the empty token are still reported as
out_of_range.404. As a consequence, value(json_pointer, default) on an
array now throws for "/x" as it already did for "/xy".

Also document why ordered_map::erase's destroy/placement-new loop on
pair<const Key, T> is kept despite [basic.life]/8 before C++20.

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

* Document the one-character array index change

Add 3.13.0 version-history entries to at, operator[], value, patch,
patch_inplace, and unflatten, and describe in exceptions.md which array
indices throw parse_error.109 and which out_of_range.404.

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

---------

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-11 08:21:41 +02:00
Niels Lohmann d540750f21 Use the with_*_t aliases in the remaining tests and docs (#5790)
#5787 missed the instantiations spelled as `basic_json <` (astyle's
formatting) or ending in the CustomBaseClass argument. Convert them,
including the binary_t.md example pointed out in review.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-09 16:56:14 +02:00
Alex Prabhat Bara 69a0c1b82c Avoid allocating temporary basic_json for cbor and msgpack object keys (#5328)
* avoid allocating temporary basic_json for CBOR and MessagePack object keys

Signed-off-by: alexprabhat99 <alexpbara@gmail.com>

* add size() to the custom object key test type

UBJSON and BJData access object keys through size() and c_str()
directly, so the key type now provides both and the comment says why.

Signed-off-by: alexprabhat99 <alexpbara@gmail.com>

* address review: drop key size()/c_str(), test keys below the depth limit

Nothing in the library calls size() or c_str() on an object key, so the
test key type only keeps data(), which JSON_DIAGNOSTICS needs.

The CBOR and MessagePack custom key tests now also nest objects deeper
than detail::recursion_depth_limit(), so keys written by
write_cbor_iterative and write_msgpack_iterative are covered as well.

Signed-off-by: alexprabhat99 <alexpbara@gmail.com>

---------

Signed-off-by: alexprabhat99 <alexpbara@gmail.com>
2026-10-09 13:22:07 +02:00
Niels Lohmann 3d7f554927 Use the with_*_t aliases in tests, examples, and docs (#5787)
* Use the with_*_t aliases in tests, examples, and docs

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

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

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

* Fix unit-large_json for clang and JSON_DIAGNOSTICS

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

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

* Use static_cast in unit-hash for clang-tidy

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

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

* Declare the expected message prefix const in unit-large_json

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

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

---------

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-08 16:11:16 +02:00
Niels LohmannandAfonso Januário a5f5d3059b Make std::hash<basic_json> consistent with operator== for numbers (#5772)
* Make std::hash<basic_json> consistent with operator== for numbers

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

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

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

Fixes #5400

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

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

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

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

* Mark the unordered_set in the hash regression test const

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

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

* Normalize -0.0 in number hashes and test range ends

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

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

* Clarify hash documentation after review

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

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

---------

Signed-off-by: Afonso Januário <afonso-januario@hotmail.com>
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
Co-authored-by: Afonso Januário <afonso-januario@hotmail.com>
2026-10-07 19:18:51 +02:00
Niels Lohmann 1c754cfe31 Copy a pair-shaped array value under JSON_BRACE_INIT_COPY_SEMANTICS (#5701)
With JSON_BRACE_INIT_COPY_SEMANTICS enabled, single-element brace
initialization from a JSON value decided whether to copy the value or
build an object by inspecting the value's runtime shape: a two-element
array whose first element is a string, such as ["key", 42], was turned
into an object instead of being copied. This made the behavior depend
on the element's content, and it did not distinguish an existing value
of this shape from a nested braced pair written in the source, such as
the inner {"key", "value"} of {{"key", "value"}}.

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

Fixes #5662.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-07 07:39:05 +02:00
Mohd Quamar TyagiandNiels Lohmann 675e519966 Allow SAX parsing of tagged CBOR (#5740)
* Allow SAX parsing of tagged CBOR

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

* Consolidate sax_parse overloads with default tag_handler parameter

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

* Add version history entry for tag_handler in sax_parse documentation

---------

Signed-off-by: Tyagiquamar <mohdquamartyagi@gmail.com>
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
Co-authored-by: Niels Lohmann <mail@nlohmann.me>
2026-10-07 07:38:24 +02:00
162e13b86f Add with_*_t alias templates to create basic_json types with changed template parameters (#5758)
* Add helper types to make it easier to create a basic_json type with modified template parameters

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

* Rename with_changed_*_t aliases to with_*_t and merge integer/unsigned aliases

Per review discussion on #3898 between gregmarr and nlohmann:
- rename with_changed_X_t to with_X_t for brevity
- replace the separate with_changed_integer_t/with_changed_unsigned_t
  aliases with a single with_integers_t<NumberIntegerType2, NumberUnsignedType2>
- add @sa doc comment links for the upcoming documentation page

Co-authored-by: Raphael Grimm <1005058+barcode@users.noreply.github.com>
Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Add documentation for the with_*_t member alias templates

Add docs/mkdocs/docs/api/basic_json/with_t.md documenting with_object_t,
with_array_t, with_string_t, with_boolean_t, with_integers_t, with_float_t,
with_allocator_t, with_json_serializer_t, with_binary_t and with_base_class_t,
with an accompanying example, and link the page from the basic_json member
types list and the mkdocs navigation.

Co-authored-by: Raphael Grimm <1005058+barcode@users.noreply.github.com>
Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Add tests for the with_*_t member alias templates

Check with std::is_same that each with_*_t alias produces the expected
basic_json type, and that with_string_t keeps nlohmann::ordered_map as
the object type when used on ordered_json.

Co-authored-by: Raphael Grimm <1005058+barcode@users.noreply.github.com>
Signed-off-by: Niels Lohmann <mail@nlohmann.me>

* Fix with_t nav entry and document chaining of the with_*_t aliases

Indent the with_t entry in mkdocs.yml so it is listed under basic_json,
explain that the aliases can be chained and work on ordered_json, and
test both, including json::with_object_t<ordered_map> == ordered_json.

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

* Add docset entry for basic_json::with_t

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

---------

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
Co-authored-by: barcode <barcode@example.com>
Co-authored-by: Raphael Grimm <1005058+barcode@users.noreply.github.com>
2026-10-06 22:33:29 +02:00
5379e04ce4 Throw type_error.321 when serializing discarded values to binary formats (#5761)
* Throw type_error.321 when serializing discarded values to binary formats

The CBOR, MessagePack, UBJSON, BJData, and BSON writers silently
skipped the payload of a value_t::discarded value nested in an array
or object, while still writing its slot in the element/member count
(and, for BSON, its entry header), producing a binary document whose
declared size does not match what was actually written.

Throw type_error.321 instead, for a discarded value anywhere in the
tree, including at the top level.

Rewritten from the original PR against the current (non-recursive
option aside) binary_writer.hpp, which has changed substantially since
this was first proposed; the out_of_range.412 MessagePack size check
and unrelated test reformatting from that PR are dropped as out of
scope here.

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

* Document and test type_error.321 for discarded binary values

Add docs for the new exception (home/exceptions.md and the Exceptions
sections of to_cbor/to_msgpack/to_ubjson/to_bjdata/to_bson) and test
coverage for a discarded value nested in an array or object, nested
deeper, and (for UBJSON/BJData) inside an optimized same-type array,
for each of CBOR, MessagePack, UBJSON, BJData, and BSON. Adjust the
three pre-existing "discarded" tests that asserted the old silent
behavior (empty/short output) to expect type_error.321 instead.

Co-authored-by: ameliabarnabyhub <312084480+ameliabarnabyhub@users.noreply.github.com>
Signed-off-by: Niels Lohmann <mail@nlohmann.me>

---------

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
Co-authored-by: ameliabarnabyhub <ameliabarnabyhub@users.noreply.github.com>
Co-authored-by: ameliabarnabyhub <312084480+ameliabarnabyhub@users.noreply.github.com>
2026-10-06 07:33:34 +02:00
Niels Lohmann 8a142bc436 Fix CI on develop after #5600, #5607, and #5755 (#5764)
* Fix CI on develop after #5600, #5607, and #5755

- binary_reader: cast the result of -1 - number back to number_integer_t,
  because a number_integer_t narrower than int is promoted to int, which
  GCC's -Warith-conversion rejects (ci_test_gcc, ci_test_standards_gcc)
- JSON_DELETE_DEPRECATED_FUNCTIONS: declare the deleted stream operators
  as function templates at namespace scope, because GCC < 5 rejects deleted
  friend functions ("can't initialize friend function") and Clang 7-9 report
  a redefinition when a class template has a deleted friend function
- docs: give the examples of JSON_USE_OBJECTS_FOR_ENUM_KEYED_MAPS "Example:"
  titles and add the page to the docset (style_check)

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

* Ignore libstdc++'s <format> sign change in the sanitizer job

libstdc++ 14's <format> initializes a size_t parameter with -1 (GCC bug
119429), so every std::format call fails ci_test_clang_sanitizer under
-fsanitize=integer (test-std-format_cpp20). Exclude only the
implicit-integer-sign-change check and only that header via
-fsanitize-ignorelist.

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

* Fix the AppVeyor (MSVC 2015-2019) build

- binary_reader: emit_signed/emit_unsigned pass integers that do not fit
  the number types to emit_float as long double, because MSVC's <cmath>
  has no integer overloads of std::isfinite (C2668 'fpclassify'), from #5607
- scalar comparisons: the friend operators take the JSON type for their
  noexcept from their parameter, because MSVC 2015/2017 take basic_json as
  the class template there (C3203) and MSVC 2019 16.0 does not see member
  types or template parameters, from #5751
- unit-conversions2: skip the !is_nothrow_constructible static_assert for
  std::optional on MSVC 2017, which evaluates the conditional noexcept as
  true (C2607), from #5754

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

* Re-amalgamate

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

* Avoid MSVC 2015's C4800 for enums with underlying type bool

MSVC 2015 warns about any conversion to bool (C4800), even with an
explicit cast, so the enum conversions from #5754 (#5671) failed the
AppVeyor build with /WX. Convert to bool by comparing with zero via the
new detail::bool_aware_static_cast, and keep doctest from printing the
enum in the test.

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

* Skip the #5650 allocator test on MSVC 2015 debug builds

MSVC 2015's debug STL constructs the containers' debug proxies through
the allocator in noexcept constructors, so countdown_allocator's failing
construction crashes test-allocator (SIGSEGV) instead of throwing
std::bad_alloc. Use the guard #5585 uses for the same reason.

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

* Skip deleted-function detection checks on MSVC 2015

MSVC 2015 does not treat selecting a deleted function in decltype as a
substitution failure, so the detection traits in
unit-delete_deprecated_functions (#5755) and the integral-key checks in
unit-element_access2 (#5657) report deleted overloads as callable there.
Calling them still fails to compile. Skip those checks for
_MSC_VER < 1910, and use the stream operators for real in the runtime
section, so MSVC 2015 still compiles them with the macro set.

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

* Split the Visual Studio 2017 AppVeyor jobs in two

The VS 2017 jobs hit AppVeyor's 60-minute limit per job while still
compiling the tests (77 of about 108 test targets after 58 minutes).
They pass /std:c++17 for everything anyway, so build only the C++17
variant of each test (JSON_TestStandards=17), and split the unit test
files across two jobs each with the new JSON_TestShard=<index>/<count>
option, which keeps every <count>-th test file starting at <index>.
The extra variants of single test files are built in shard 0 only.

CMAKE_OPTIONS is no longer quoted in appveyor.yml, so that it can hold
more than one option.

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

* Fix std::terminate when converting std::optional with MSVC 2017

MSVC 2017 evaluates std::is_nothrow_assignable<json&, const T&> as true
even if T's to_json throws, so to_json(json&, const std::optional<T>&)
was noexcept there and the exception from #5642's test called
std::terminate instead of propagating. Make that conversion never
noexcept on MSVC 2017; all other compilers keep the exact condition.
The static_asserts on the condition are skipped for MSVC 2017; the
runtime check that the exception propagates still runs there.

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

---------

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-06 07:22:55 +02:00
Niels Lohmann 23d3b373e1 Add JSON_DELETE_DEPRECATED_FUNCTIONS to delete the deprecated functions (#5755)
* Add JSON_DELETE_DEPRECATED_FUNCTIONS to delete the deprecated functions

Defining JSON_DELETE_DEPRECATED_FUNCTIONS to 1 (or the CMake option
JSON_DeleteDeprecatedFunctions) declares every deprecated function as
deleted instead of deprecated, so that code that is not ready for 4.0.0
no longer compiles. A deleted function still takes part in overload
resolution, so from_*(ptr, len) cannot silently bind len to the strict
parameter of from_*(InputType&&, bool); the roadmap now plans to keep
these overloads deleted in 4.0.0 instead of removing them.

The legacy discarded-value comparison is left to its own macro.

Also update the 4.0 roadmap: add JSON_DISABLE_TUPLE_REFERENCE_CONVERSION
and JSON_DELETE_DEPRECATED_FUNCTIONS to the macro table, add the
from_bjdata/from_bon8 (ptr, len) overloads to the deprecated functions,
document the macro in the migration guide, and fix the docs style check
findings (example titles, missing docset entry for JSON_STRICT_BINARY_UTF8).

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

* Declare each deprecated function once and guard only its body

Instead of repeating every deprecated declaration in an
#if JSON_DELETE_DEPRECATED_FUNCTIONS branch, keep one declaration
(with its deprecation attribute) and switch only between "= delete;"
and the function body. Suggested by @gregmarr in the review.

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

---------

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-04 22:11:34 +02:00
Niels Lohmann c5a7a4b46d Add deprecated from_bon8/from_bjdata(ptr, len) overloads (#5688)
from_bon8(ptr, len) and from_bjdata(ptr, len) had no overload for a
pointer and a length, unlike from_cbor/from_msgpack/from_ubjson/
from_bson. The call instead bound to from_*(InputType&&, bool strict),
which read ptr as a NUL-terminated C string via strlen and silently
converted len to the strict flag. Data containing a 0x00 byte was cut
off there; data without one was read past the end of the buffer.

Add a deprecated (ptr, len, strict, allow_exceptions) overload for
each function that forwards to (ptr, ptr + len, ...), matching the
existing deprecated overloads of the other four binary readers. Since
neither function ever had this overload, the deprecation is declared
as of version 3.13.0, the next unreleased version, rather than the
version each function was originally added in.

Fixes #5648.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-04 22:11:34 +02:00
Niels Lohmann 4f69be80d6 Clarify wording in diff documentation (#5759)
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-04 18:20:20 +02:00