The lexer's token dispatch had `case '\0':` fall through to the same
`end_of_input` handling as the real end-of-file sentinel, with a comment
claiming the NUL case was "needed when parsing from string literals".
That rationale no longer holds: input_adapter(const char*) already uses
strlen() to compute its range, so it never hands the lexer a trailing
NUL, and the const-char* overload is the only "string literal" path the
comment could be referring to. In practice, `case '\0':` only ever fired
on a genuine embedded or trailing NUL byte in real input data (e.g. a
std::string with '\0' appended), which was then silently swallowed as if
it were EOF instead of producing the parse_error.101 any other
unexpected byte gets. Two more spots in the comment-skipping logic had
the same NUL-as-EOF idiom, stopping a `//` or `/* */` comment scan early
at an embedded NUL instead of continuing to the real terminator.
Removing all three still left one real regression: input_adapter's
T(&array)[N] overload (used for a string literal like
json::parse("123"), as opposed to a decayed const char* pointer) passes
the array's full extent through unchanged, trailing '\0' included. That
path was relying on the lexer's old NUL-as-EOF behavior to make ordinary
literal parsing work at all. It now gets its own strlen()-like handling
for char arrays specifically: a single trailing NUL terminator is
excluded, mirroring the pointer overload, while non-char arrays (e.g.
uint8_t buffers for binary formats) are left untouched since a trailing
zero byte there may be data.
Also updates a few existing tests that (mostly incidentally) depended on
a trailing NUL being swallowed - std::array<uint8_t, 5>{"true"} left the
5th element zero-initialized - and adds an FAQ entry.
Signed-off-by: Niels Lohmann <niels.lohmann@gmail.com>
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01N4RQ1Ahan5YAGbnAQGjZTY
`lexer::get()` copied every scanned character into `token_string` on the
whole successful-parse hot path, yet that buffer is consumed only by
`get_token_string()` when rendering the "last read" fragment of a parse
error. On well-formed input the per-byte copy (plus the `unget()` pop)
is pure overhead that is always discarded.
For seekable input adapters - random-access, single-byte iterators such
as those backing `std::string`, `const char*`, and `std::vector<char>` -
the offending token is now reconstructed on demand from the input when
an error is reported, using a saved start offset, and the eager copy is
skipped. Streaming adapters (file, istream, wide-string, and user-defined
adapters) keep the eager copy; the strategy is chosen at compile time via
`input_adapter_supports_seek`, so adapters without the capability are
unaffected.
Error messages are byte-for-byte identical across all adapters, verified
by a new parity regression test. Microbenchmark (4 MB mixed JSON, parsed
from a std::string): ~149 -> ~160 MB/s, about +8%.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>
PR #4873 introduced a safety check in sax_parse functions to catch
nullptr passed as SAX parser object, which had been already annotated by
JSON_HEDLEY_NON_NULL macro.
Compilers (e.g. clang) which respected the non-null annotation tended to
eliminate the safety check completely in optimized builds, while
compilers which did not, compiled the safety check in. This led to
different behaviors accross different compilers/platforms and/or build
types (debug, release).
This commit reverts PR #4873 to remove this discrepancy. Passing null to
non-null annotated parameter is considered to be undefined behavior.
Fixes#5048
Signed-off-by: Richard Musil <risa2000x@gmail.com>
Co-authored-by: Richard Musil <risa2000x@gmail.com>
* Add implementation to retrieve start and end positions of json during parse
* Add more unit tests and add start/stop parsing for arrays
* Add raw value for all types
* Add more tests and fix compiler warning
* Amalgamate
* Fix CLang GCC warnings
* Fix error in build
* Style using astyle 3.1
* Fix whitespace changes
* revert
* more whitespace reverts
* Address PR comments
* Fix failing issues
* More whitespace reverts
* Address remaining PR comments
* Address comments
* Switch to using custom base class instead of default basic_json
* Adding a basic using for a json using the new base class. Also address PR comments and fix CI failures
* Address decltype comments
* Diagnostic positions macro (#4)
Co-authored-by: Sush Shringarputale <sushring@linux.microsoft.com>
* Fix missed include deletion
* Add docs and address other PR comments (#5)
* Add docs and address other PR comments
---------
Co-authored-by: Sush Shringarputale <sushring@linux.microsoft.com>
* Address new PR comments and fix CI tests for documentation
* Update documentation based on feedback (#6)
---------
Co-authored-by: Sush Shringarputale <sushring@linux.microsoft.com>
* Address std::size_t and other comments
* Fix new CI issues
* Fix lcov
* Improve lcov case with update to handle_diagnostic_positions call for discarded values
* Fix indentation of LCOV_EXCL_STOP comments
* fix amalgamation astyle issue
---------
Co-authored-by: Sush Shringarputale <sushring@linux.microsoft.com>
* Move UDLs into nlohmann::literals::json_literals namespace
* Add 'using namespace' to unit tests
* Add 'using namespace' to examples
* Add 'using namespace' to README
* Move UDL mkdocs pages out of basic_json/
* Update documentation
* Update docset index
* Add JSON_GlobalUDLs CMake option
* Add unit test
* Build examples without global UDLs
* Add CI target
* 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
Niels LohmannandClaude Sonnet 5
Angadi56
Niels LohmannandClaude Opus 4.8
risa2000andRichard Musil
Nikhil
chirszandNiels Lohmann
Sushrut ShringarputaleandSush Shringarputale
laterlaugh
