Niels LohmannandClaude Sonnet 5.5
18138227dc
* Scan the buffer of a FILE in bulk with glibc and the Apple C library Parsing from a FILE* still read one character at a time through getc_unlocked(), while a std::istream has its get area scanned in bulk. file_input_adapter now offers the lexer the same kind of window into the buffer of the FILE: it reads the fields that the C library's own getc_unlocked() macro reads (glibc: _IO_read_ptr and _IO_read_end; Apple: _p and _r) and consumes exactly the characters getc_unlocked() would return, so the file is left where it was left before. The part of the current token in a buffer that is about to be refilled is kept for error messages, as for streams. The window needs the file locked for the whole parse, so JSON_DISABLE_UNLOCKED_FILE_IO and MemorySanitizer builds turn it off; uClibc, which defines __GLIBC__ but has other fields, does not get it. parse() from a FILE* gets 2.0-2.6x as fast on an Apple M1 Max and 1.7-2.2x on x86-64 (glibc, GCC 15 and Clang 21), accept() 2.9-4.4x; that is about as fast as parsing from a std::ifstream. The new tests read with FILE buffers of 1 to 70 bytes and unbuffered files, after ungetc(), with SAX positions and with binary strings across the buffer's edges. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Tests: no setvbuf() buffer below 2 bytes on Windows The Microsoft C runtime rejects a _IOFBF buffer size below 2 as an invalid parameter and ends the process (0xc0000409), which made test-file_input fail on all MSVC and clang-cl jobs. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Fix CI: astyle formatting in unit-file_input.cpp Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Tests: limit the multi-character ungetc() test to glibc and Apple The Windows C runtime only supports one pushed-back character, which broke the Windows CI jobs. Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01N5NasEsrzHhSNouxSoEwqz Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Tests: sweep_allocator::construct() accepts pointers to const Recent libc++ (emsdk latest) probes construct(const T*, const T&) in an unevaluated context while checking for trivial copies; the static_cast to void* in the noexcept specification then fails to compile. Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01N5NasEsrzHhSNouxSoEwqz (cherry picked from commit 794bf70823c12a2a1cb2a8a95f34dfb6357746a8) Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Tests: guard sweep_allocator::construct() against const types instead of const_cast The const_cast added in the previous commit is rejected by cppcoreguidelines-pro-type-const-cast (clang-tidy). Make construct() not viable for const U instead, which is what libc++ probes for. Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01N5NasEsrzHhSNouxSoEwqz (cherry picked from commit de099fa607001b710862fd1bbecef3609c54cbc4) Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Fix CI: astyle and clang-tidy for sweep_allocator::construct() astyle 3.4.13 reformats the enable_if<!...> default template argument (Check amalgamation). Delete the const overload instead, which makes the libc++ probe for const objects fail in the SFINAE context just the same and needs no <type_traits>. Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01N5NasEsrzHhSNouxSoEwqz Signed-off-by: Niels Lohmann <mail@nlohmann.me> --------- Signed-off-by: Niels Lohmann <mail@nlohmann.me> Co-authored-by: Claude Sonnet 5.5 <noreply@anthropic.com>
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