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Niels Lohmann
5b4c8f9b00
* Speed up the lexer: own float parser, string scan, and \u table Give the library its own correctly rounded float converter for binary32 and binary64 (IEEE 754), and speed up the lexer's string and escape scanning. The converter splits a number token into sign, significand, and decimal exponent, then tries Clinger's fast path, then a templated Eisel-Lemire step, and falls back to an exact big-integer digit comparison for tokens with more than 19 significant digits whose two candidate values round differently. This replaces std::from_chars and strtod/strtof for both formats, so parsed values no longer depend on the C/C++ library or the current locale. The strtold fallback kept for other long double formats (x87, binary128) now also copies a multi-byte decimal point correctly, fixing #5660. eisel_lemire() and decimal_to_float() are always inlined so callers keep the whole conversion in their hot loop. The string-scanning kernels in string_scan.hpp find a stop byte with the trailing-zero count of the SWAR mask instead of a byte loop, and scalar_string_bulk_run() validates a run of multi-byte UTF-8 sequences one after another instead of re-searching after each one. get_codepoint() decodes a contiguous \uXXXX escape with one table lookup per byte instead of four range-checked get() calls; the streaming path and all error positions are unchanged. Adds 508 generated hard float-parsing cases with expected binary32 and binary64 bits, and kernel-comparison tests for the string scans and the escape table against byte-by-byte references. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Fix CI warnings in own float parser - pow5_table.hpp: pow5_128_largest_power was unused in this branch's own code (GCC -Werror=unused-const-variable); tie it to the table size with a static_assert instead of removing it, since a later branch in the stack (json-view/23-zmij) uses it. - number_parse.hpp: rename the local variable `copy` to `buffer` to satisfy cpplint's build/include_what_you_use check. - unit-class_lexer.cpp: extend the NOLINT list on the seeded mt19937 with bugprone-random-generator-seed, and parenthesize `8 * sizeof(Bits) - 1` for clang-tidy. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Load string scan words with memcpy and use MSVC bit-scan intrinsics Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Reword float conversion notes for the string type and number_float_t docs Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Fix clang-tidy 22 findings in unit-class_lexer.cpp Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Mark the unsigned long of the MSVC bit scans for cpplint Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Regenerate the amalgamated headers Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Drop the position updates in the bulk \u path, which #5809 made unused Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Address review: std::any_of in has_nonzero_digit, comment punctuation Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Use data() instead of c_str() in the multi-byte decimal point path Signed-off-by: Niels Lohmann <mail@nlohmann.me> --------- Signed-off-by: Niels Lohmann <mail@nlohmann.me>
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