1 Commits

Include renames

Author	SHA1	Message	Date
Niels LohmannandClaude Sonnet 5.5	33f15727ce	Parse JSON in one block of memory with a fused pointer-based parser (#6031) ... * Parse JSON in one block of memory with a fused pointer-based parser The parser and the lexer exchange one token at a time, and the lexer keeps its state (the current character, a pending unget, where the token starts) in members, which every character pays for: json::accept() of twitter.json took 2.8x as long as json_document::accept(). detail::contiguous_parser reads text in one block of memory through a local pointer, with the grammar, the whitespace and the tokens in one loop (after yyjson's reader), and drives a SAX handler: parse()'s DOM handler, accept()'s handler, or the user's handler of sax_parse(). It is used with the default options (no callback, no comments, no trailing commas; sax_parse() with strict = true). Errors are reported by the library parser, so the exception, its message and its position stay the same. contiguous_parser stops at the token that the library parser would reject, before reporting it, so the events up to the error are the same; then: - parse() runs the library parser with a handler that only reports the error (json_sax_error_reporter), with the lexer of parse(), which is instantiated anyway; - sax_parse() runs it with a handler that forwards only parse_error() to the user's handler (json_sax_error_forwarder), so no event arrives twice; - accept() returns the verdict. A handler that returns false stops the parse as before. An error at the end of a large input costs parse() about 1.2x of what it cost before. On an Apple M1 Max: accept() 1.6-2.0x as fast, parse() 10-16% faster, ordered_json 11-16%, sax_parse() with a user's handler 1.36-1.46x, small messages 12-22% (parse()) and 2.1-2.4x (accept()). On x86-64 (GCC 15, Clang 21): accept() 1.6-1.9x, parse() 5-17%, ordered_json 12-19%, sax_parse() 1.32-1.57x. A translation unit that parses a string compiles 3% (-O0) and 9% (-O2) slower. unit-contiguous_parser.cpp compares the contiguous path with the byte path (std::list iterators) on corner cases, generated documents, their truncations and mutations, deep nesting, and narrow number types: the same values with the same number types and float bits, exception messages, accept() verdicts and sax_parse() events. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Fix CI: unused parameter without exceptions, cpplint, BUILD.bazel - json_sax_error_reporter::parse_error: mark the exception unused, as JSON_THROW does not use it with JSON_NOEXCEPTION - unit-contiguous_parser.cpp: compare the exceptions of both paths only when exceptions are enabled (invalid input aborted the test otherwise) - silence cpplint's readability/braces false positives on the if statements inside the parser's macros - add contiguous_parser.hpp to BUILD.bazel Signed-off-by: Niels Lohmann <mail@nlohmann.me> * accept(): skip digits without computing their value accept() needs the value of a number only for a float whose exponent may reach the largest value. skip_digits() finds the end of the digits without the multiply-adds of accumulate_digits(), and once an 8-byte word fails the digit test, the remaining loop needs no bounds check: a non-digit is in that word. The value is computed afterwards for the rare floats that need it. accept() of canada.json: -16 % on Apple M1, -22 % with GCC 15 and -21 % with Clang 21 on x86-64; files with many numbers -9 to -15 %. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Tests: mark parser callback in unit-contiguous_parser noexcept Fixes the -Werror=noexcept failure with GCC 26 (ci_test_standards_gcc (26)). 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> * Contiguous parser: review fixes (wording, macros, diagnostic positions) - "default parser" instead of "library parser" in comments and tests - the three comments in json.hpp say the same thing - current() replaces the repeated `p != end ? *p : 0` - the backslashes of each macro are aligned - the docs say that JSON_DIAGNOSTIC_POSITIONS turns the fast path off 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>	2026-11-10 07:08:44 +01:00