Files
json/include/nlohmann/detail/macro_unscope.hpp
T
Niels LohmannandClaude Sonnet 5.5 18138227dc Scan the buffer of a FILE in bulk with glibc and the Apple C library (#6030)
* 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>
2026-11-07 10:11:09 +01:00

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1.9 KiB
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// __ _____ _____ _____
// __| | __| | | | JSON for Modern C++
// | | |__ | | | | | | version 3.12.0
// |_____|_____|_____|_|___| https://github.com/nlohmann/json
//
// SPDX-FileCopyrightText: 2013-2026 Niels Lohmann <https://nlohmann.me>
// SPDX-License-Identifier: MIT
#pragma once
// clean up
#undef JSON_ASSERT
#undef JSON_INTERNAL_CATCH
#undef JSON_THROW
#undef JSON_PRIVATE_UNLESS_TESTED
#undef NLOHMANN_BASIC_JSON_TPL_DECLARATION
#undef NLOHMANN_BASIC_JSON_TPL
#undef JSON_EXPLICIT
#undef NLOHMANN_CAN_CALL_STD_FUNC_IMPL
#undef JSON_INLINE_VARIABLE
#undef JSON_NO_UNIQUE_ADDRESS
#undef JSON_DISABLE_ENUM_SERIALIZATION
#undef JSON_DISABLE_TUPLE_REFERENCE_CONVERSION
#undef JSON_UNLOCKED_FILE_IO
#undef JSON_FILE_WINDOW
#undef JSON_DTOA_SSE2
#undef JSON_DTOA_NEON
#undef JSON_LITTLE_ENDIAN_TARGET
#undef JSON_BIG_ENDIAN_TARGET
#undef JSON_SCAN_NEON
#undef JSON_SCAN_SSE2
#undef JSON_SCAN_SSSE3
#undef JSON_SCAN_SSSE3_DISPATCH
#undef JSON_SCAN_SSSE3_TARGET
#undef JSON_SCAN_VECTOR
#undef JSON_SCAN_VECTOR_UTF8
#ifndef JSON_TEST_KEEP_MACROS
#undef JSON_CATCH
#undef JSON_TRY
#undef JSON_HAS_CPP_11
#undef JSON_HAS_CPP_14
#undef JSON_HAS_CPP_17
#undef JSON_HAS_CPP_20
#undef JSON_HAS_CPP_23
#undef JSON_HAS_CPP_26
#undef JSON_HAS_FILESYSTEM
#undef JSON_HAS_EXPERIMENTAL_FILESYSTEM
#undef JSON_HAS_THREE_WAY_COMPARISON
#undef JSON_HAS_RANGES
#undef JSON_HAS_RANGE_VIEW_CONVERSION
#undef JSON_HAS_STD_FORMAT
#undef JSON_HAS_STATIC_RTTI
#undef JSON_USE_LEGACY_DISCARDED_VALUE_COMPARISON
#undef JSON_BRACE_INIT_COPY_SEMANTICS
#undef JSON_PRECISE_STREAM_POSITION
#undef JSON_STRICT_NUL_HANDLING
#undef JSON_STRICT_BINARY_UTF8
#undef JSON_DELETE_DEPRECATED_FUNCTIONS
#undef JSON_USE_OBJECTS_FOR_ENUM_KEYED_MAPS
#undef JSON_DISABLE_STREAM_BULK_SCAN
#undef JSON_DISABLE_UNLOCKED_FILE_IO
#endif
#include <nlohmann/thirdparty/hedley/hedley_undef.hpp>