Niels Lohmann
6a023f469c
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>
2.4 KiB
License
The class is licensed under the MIT License:
Copyright © 2013-2026 Niels Lohmann
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The class contains the UTF-8 Decoder from Bjoern Hoehrmann which is licensed under the MIT License (see above). Copyright © 2008-2009 Björn Hoehrmann bjoern@hoehrmann.de
The class contains a slightly modified version of the Grisu2 algorithm from Florian Loitsch which is licensed under the MIT License (see above). Copyright © 2009 Florian Loitsch
The class contains a copy of Hedley from Evan Nemerson which is licensed as CC0-1.0.
The class contains an adapted version of the Eisel-Lemire algorithm, its table of powers of five, and its digit comparison for long numbers from fast_float by Daniel Lemire and contributors, which is available under the MIT License (used here), the Apache 2.0 License, and the Boost Software License. Copyright © 2021 The fast_float authors