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>
The comparison operators taking a scalar (==, !=, <, <=, >, >=, and
C++20's <=>) convert the scalar to a basic_json and compare, but were
unconditionally noexcept. When that conversion throws, the program
called std::terminate instead of propagating the exception, e.g. when
comparing a json with a string literal under memory pressure
(std::bad_alloc) or with an enum value not mapped by
NLOHMANN_JSON_SERIALIZE_ENUM_STRICT (out_of_range.410). clang-tidy
22.1 reports the latter as bugprone-exception-escape.
Declare the 16 scalar overloads
noexcept(std::is_nothrow_constructible<basic_json, ScalarType>::value):
they stay noexcept for numbers, Booleans, nullptr, and plain enums,
and are noexcept(false) for strings and enums whose to_json may throw.
The comparisons of two basic_json values are unchanged.
Restore the strict-enum comparisons removed from unit-conversions.cpp
in the previous PR, check that comparing an unmapped strict enum now
throws, and pin the new exception specifications in unit-noexcept.cpp.
Document the exception safety of overload (2) on all seven operator
pages. Ran make amalgamate.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Review and extend the documentation, and check it in CI
A review of all documentation pages found factual errors, dead links,
missing cross-references, and gaps in examples. This fixes them and adds
checks so the same problems are caught automatically.
Fixes:
- wrong signatures and version histories (operator!= C++20 member,
binary() subtype type, get<PointerType>(), JSON_NO_THREAD_LOCAL, ...)
- stale descriptions (number parsing since #5283, UBJSON table, SAX
example that no longer compiled, tsl::ordered_map advice)
- dead internal and external links; repology.org badges (the domain is
suspended) replaced by badges that query the registries directly
- deprecation notes link the migration guide; the guide itself fixed
Additions:
- "See also" sections, cross-references, 25 runnable examples, 12
Mermaid diagrams, new API pages for json_pointer::operator<=> and
byte_container_with_subtype::operator==/!=
- landing page, guides for untrusted input and performance
- "unreleased" badge after versions newer than the latest release
Checks:
- strict documentation build (broken links/anchors fail it); CI and
the publish workflow fetch the full history the build needs
- weekly external link check, Mermaid syntax check in CI
- check_structure.py: example titles, heading levels, alt texts,
header links, docset index coverage; its unused-example check works
again
- all examples produce the same output on every platform
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Keep the customer links that could not be fixed
A dead link on the customers page is still the evidence of where the
use of the library was documented. Keep the original URLs of the entries
without a working replacement (Marne, Cisco Webex Desk Camera, Philips
Hue, CyberArk) and exclude exactly these URLs from the link check.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Correct the duplicate-key recipe's claim about SAX positions
The SAX interface's key() receives no position either; only parse_error()
does. Also note that the recipe does not report the path to the repeated
key (see discussion #5085).
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Say the library is available as a single header and mention json_fwd.hpp
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Correct documentation errors found while hunting for bugs
- patch/patch_inplace: list the JSON pointer errors parse_error.106-109
and out_of_range.402/404, and quote the actual parse_error.105 message.
- unflatten: list parse_error.106/107/108 and out_of_range.404.
- to_bson: list out_of_range.415 (binary subtype above 255) and note
that 412 and 415 are new in 3.13.0.
- to_string: state that string_t must be convertible to std::string, also
in the StringType requirements table.
- JSON Lines: a `while (input >> j)` loop also throws after the last value
for concatenated JSON values; show a loop that works for both.
- BON8: a string gets 0xFF only if nothing follows it in the message; a
string at the end of an array or object is ended by 0xFE.
- custom_string_type.hpp: add operator+=(char), which the "Always
required" list asks for (json_pointer::to_string, flatten, unflatten,
and diff did not compile), and an ADL int_to_string for diff and items.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Cache the release headers with functools.lru_cache
Codacy (Pylint) flagged the mutable default argument that header() used
as its cache. functools.lru_cache keeps the same memoization without it.
The script's output is unchanged.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
---------
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* 📝 Fix stale 3.12.x placeholder in operator_ne.md version history
PR #5253 (removing the hand-written operator!= to fix #3868/P2468R2)
merged after the earlier 3.12.x -> 3.13.0 global sweep, so its new
version-history entries were written with the stale placeholder.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* 🐛 Fix stale twitter.com link in docset.json
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
---------
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* Fix#3868: Remove operator!= to enable P2468R2 rewritten candidate synthesis
Under C++20 P2468R2, a hand-written operator!= suppresses the compiler's
rewritten-candidate synthesis for operator==, preventing heterogeneous
comparisons like `std::string s; json j; s == j;` from compiling.
Fix by removing the hand-written operator!=, allowing the compiler to
synthesize != as !(a==b) in all language modes (C++20 member functions
and pre-C++20 friend functions).
Behavior change: operator!= now returns !(a==b) unconditionally, including
for special values like NaN and discarded. This means:
- NaN != NaN now returns true (matches IEEE-754 semantics)
- discarded != x now returns true for any x (matches !(discarded == x))
This also fixes underlying defects in previously-working code:
- Restores direct == comparison for views vs json (reverts std::ranges::equal
workaround added in PR #3950 to dodge this bug)
- Re-enables std::string == json comparisons (uncomments check in
unit-constructor1.cpp)
Fixes: #3868, #3979
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
* 🚨 fix warning
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
---------
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
Co-authored-by: Claude Sonnet 5 <noreply@anthropic.com>
* Add C++20 3-way comparison operator and fix broken comparisons
Fixes#3207.
Fixes#3409.
* Fix iterators to meet (more) std::ranges requirements
Fixes#3130.
Related discussion: #3408
* Add note about CMake standard version selection to unit tests
Document how CMake chooses which C++ standard version to use when
building tests.
* Update documentation
* CI: add legacy discarded value comparison
* Fix internal linkage errors when building a module
