operator>> is documented to leave the stream positioned right after the
parsed value, so that concatenated JSON values can be read back to back.
That did not hold for numbers: a number is only terminated by the
character following it, and lexer::scan_number() reads that character
and calls unget() -- which is simulated and rewinds only the lexer's own
bookkeeping. input_stream_adapter consumes via sbumpc() with no matching
sungetc(), so the terminating character stayed consumed and the next
extraction started one byte too late ('1true' left the stream at 'rue').
Propagating unget() to the adapter directly does not work: next_unget
makes the following get() replay the cached character, so the terminator
would be delivered twice. Instead, restore the still-pending character
once at the end of a non-strict parse, where the input is handed back to
the caller:
- input_stream_adapter gains unget_character() (sungetc()) and advertises
it via supports_unget, detected the same way as supports_seek.
- lexer::restore_pending_unget() turns a pending simulated unget of a
real (non-EOF) character into a real one and clears next_unget so the
character is not also replayed. It is a no-op for adapters that cannot
unget, and reports failure when sungetc() fails, in which case the
input is left as it was before.
- parser calls it on the three non-strict paths, i.e. for operator>> and
sax_parse(strict = false).
Strict parse()/accept() are unaffected: they require the input to end
after the value, so the character is consumed by the end-of-input check
anyway. Parse error messages and reported positions are unchanged.
Signed-off-by: Niels Lohmann <mail@nlohmann.me>
`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>
* fix: integer parsed as float when EINTR set in errno
* chore: make amalgamate
* chore: make pretty
---------
Co-authored-by: Stuart Gorman <Stuart.Gorman@kallipr.com>
* Add versioned inline namespace
Add a versioned inline namespace to prevent ABI issues when linking code
using multiple library versions.
* Add namespace macros
* Encode ABI information in inline namespace
Add _diag suffix to inline namespace if JSON_DIAGNOSTICS is enabled, and
_ldvcmp suffix if JSON_USE_LEGACY_DISCARDED_VALUE_COMPARISON is enabled.
* Move ABI-affecting macros into abi_macros.hpp
* Move std_fs namespace definition into std_fs.hpp
* Remove std_fs namespace from unit test
* Format more files in tests directory
* Add unit tests
* Update documentation
* Fix GDB pretty printer
* fixup! Add namespace macros
* Derive ABI prefix from NLOHMANN_JSON_VERSION_*
I tested following strings with invalid surrogate pair and unpaired surrogate in files:
1. `"a\uD800\uD800x"`
2. `"a\uD800x"`
The error messge was: "... invalid string: surrogate U+DC00..U+DFFF must be followed by U+DC00..U+DFFF; ..."
I think it must be: "... invalid string: surrogate U+D800..U+DBFF must be followed by U+DC00..U+DFFF; ..."
Niels Lohmann