mirror of
https://github.com/fastfloat/fast_float.git
synced 2026-10-30 19:07:16 +08:00
1051 lines
35 KiB
C++
1051 lines
35 KiB
C++
#ifndef FASTFLOAT_ASCII_NUMBER_H
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#define FASTFLOAT_ASCII_NUMBER_H
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#include <cctype>
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#include <cstdint>
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#include <cstring>
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#include <iterator>
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#include <limits>
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#include <type_traits>
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#include "float_common.h"
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#if FASTFLOAT_X86_SIMD
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#include <immintrin.h>
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#elif FASTFLOAT_ARM_NEON
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#include <arm_neon.h>
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#endif
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namespace fast_float {
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template <typename UC>
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fastfloat_really_inline FASTFLOAT_CONSTEVAL bool has_simd_opt() noexcept {
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#ifdef FASTFLOAT_USE_SIMD
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return std::is_same<UC, char16_t>::value;
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#else
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return false;
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#endif
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}
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// Next function can be micro-optimized, but compilers are entirely
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// able to optimize it well.
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template <typename UC>
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fastfloat_really_inline FASTFLOAT_CONSTEXPR14 bool is_integer(UC c) noexcept {
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const auto d = c - UC('0');
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// UC may be signed.
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return d >= 0 && d <= 9;
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}
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#if FASTFLOAT_IS_BIG_ENDIAN
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#if FASTFLOAT_HAS_BYTESWAP
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namespace {
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using std::byteswap;
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}
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#else
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fastfloat_really_inline constexpr uint64_t byteswap(uint64_t val) noexcept {
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return (val & 0xFF00000000000000) >> 56 | (val & 0x00FF000000000000) >> 40 |
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(val & 0x0000FF0000000000) >> 24 | (val & 0x000000FF00000000) >> 8 |
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(val & 0x00000000FF000000) << 8 | (val & 0x0000000000FF0000) << 24 |
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(val & 0x000000000000FF00) << 40 | (val & 0x00000000000000FF) << 56;
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}
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fastfloat_really_inline constexpr uint32_t byteswap(uint32_t val) noexcept {
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return (val >> 24) | ((val >> 8) & 0x0000FF00u) | ((val << 8) & 0x00FF0000u) |
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(val << 24);
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}
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#endif
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#endif
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// Read UCs into an unsigned integer. Truncates UC if not char.
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template <typename T, typename UC>
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fastfloat_really_inline FASTFLOAT_CONSTEXPR20 T
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read_chars_to_unsigned(UC const *chars) noexcept {
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if (is_constant_evaluated() || !std::is_same<UC, char>::value) {
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T val = 0;
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for (uint_fast8_t i = 0; i != sizeof(T); ++i) {
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val |= T(uint8_t(*chars)) << (i * 8);
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++chars;
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}
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return val;
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}
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T val;
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std::memcpy(&val, chars, sizeof(T));
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#if FASTFLOAT_IS_BIG_ENDIAN
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// Need to read as-if the number was in little-endian order.
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val = byteswap(val);
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#endif
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return val;
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}
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#if FASTFLOAT_USE_SIMD
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#if FASTFLOAT_X86_SIMD
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fastfloat_really_inline uint64_t simd_read8(__m128i const data) {
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// _mm_packus_epi16 is SSE2, converts 8×u16 → 8×u8
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__m128i const packed = _mm_packus_epi16(data, data);
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#if FASTFLOAT_64BIT
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return static_cast<uint64_t>(_mm_cvtsi128_si64(packed));
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#elif FASTFLOAT_VISUAL_STUDIO
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// Visual Studio doesn't support _mm_cvtsi128_si64 on 32-bit targets, so we
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// use the union trick. Let's compiler do it works well, because it is a POD
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// type.
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return packed.m128i_u64[0];
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#else
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uint64_t value;
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// Visual Studio + older versions of GCC don't support _mm_storeu_si64
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_mm_storel_epi64(reinterpret_cast<__m128i *>(&value), packed);
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return value;
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#endif
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}
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fastfloat_really_inline uint64_t simd_read8(char16_t const *chars) {
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FASTFLOAT_SIMD_DISABLE_WARNINGS
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// unaligned SIMD instruction -> all fine.
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return simd_read8(_mm_loadu_si128(reinterpret_cast<__m128i const *>(chars)));
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FASTFLOAT_SIMD_RESTORE_WARNINGS
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}
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#elif FASTFLOAT_ARM_NEON
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fastfloat_really_inline uint64_t simd_read8(uint16x8_t const &data) {
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uint8x8_t utf8_packed = vmovn_u16(data);
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return vget_lane_u64(vreinterpret_u64_u8(utf8_packed), 0);
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}
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fastfloat_really_inline uint64_t simd_read8(char16_t const *chars) {
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FASTFLOAT_SIMD_DISABLE_WARNINGS
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return simd_read8(vld1q_u16(reinterpret_cast<uint16_t const *>(chars)));
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FASTFLOAT_SIMD_RESTORE_WARNINGS
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}
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#endif // FASTFLOAT_X86_SIMD
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#endif
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// MSVC SFINAE is broken pre-VS2017
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#if defined(_MSC_VER) && _MSC_VER <= 1900
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template <typename UC>
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#else
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template <typename UC, FASTFLOAT_ENABLE_IF(!has_simd_opt<UC>()) = 0>
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#endif
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// dummy for compile
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uint64_t simd_read8(UC const *) {
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return 0;
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}
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// credit @aqrit
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fastfloat_really_inline FASTFLOAT_CONSTEXPR14 uint32_t
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parse_8_digits(uint64_t val) noexcept {
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uint64_t const mask = 0x000000FF000000FF;
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uint64_t const mul1 = 0x000F424000000064; // 100 + (1000000ULL << 32)
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uint64_t const mul2 = 0x0000271000000001; // 1 + (10000ULL << 32)
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val -= 0x3030303030303030;
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val = (val * 10) + (val >> 8); // val = (val * 2561) >> 8;
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val = (((val & mask) * mul1) + (((val >> 16) & mask) * mul2)) >> 32;
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return static_cast<uint32_t>(val);
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}
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// Call this if chars are definitely 8 digits.
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template <typename UC>
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fastfloat_really_inline FASTFLOAT_CONSTEXPR20 uint32_t
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parse_8_digits(UC const *chars) noexcept {
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if (is_constant_evaluated() || !has_simd_opt<UC>()) {
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return parse_8_digits(
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read_chars_to_unsigned<uint64_t>(chars)); // truncation okay
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}
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return parse_8_digits(simd_read8(chars));
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}
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// credit @aqrit
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fastfloat_really_inline constexpr bool
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is_made_of_8_digits(uint64_t val) noexcept {
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return !((((val + 0x4646464646464646) | (val - 0x3030303030303030)) &
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0x8080808080808080));
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}
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fastfloat_really_inline constexpr bool
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is_made_of_4_digits(uint32_t val) noexcept {
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return !((((val + 0x46464646) | (val - 0x30303030)) & 0x80808080));
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}
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fastfloat_really_inline FASTFLOAT_CONSTEXPR14 uint32_t
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parse_4_digits(uint32_t val) noexcept {
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val -= 0x30303030;
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val = (val * 10) + (val >> 8);
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return (((val & 0x00FF00FF) * 0x00640001) >> 16) & 0xFFFF;
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}
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#if FASTFLOAT_USE_SIMD
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#if FASTFLOAT_X86_SIMD
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#if FASTFLOAT_X86_SIMD >= 31
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// credit @hedgehoginthecpp
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fastfloat_really_inline __m128i parse_4x4_digits(__m128i data) noexcept {
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// 1. convert from ASCII '0' .. '9' to numbers 0 .. 9
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const __m128i ascii0 = _mm_set1_epi8('0');
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const __m128i t0 = _mm_subs_epu8(data, ascii0);
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// 2. convert to 2-digit numbers
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const __m128i mul_1_10 =
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_mm_setr_epi8(10, 1, 10, 1, 10, 1, 10, 1, 10, 1, 10, 1, 10, 1, 10, 1);
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const __m128i t1 = _mm_maddubs_epi16(t0, mul_1_10);
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// 3. convert to 4-digit numbers
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const __m128i mul_1_100 = _mm_setr_epi16(100, 1, 100, 1, 100, 1, 100, 1);
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return _mm_madd_epi16(t1, mul_1_100);
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}
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#endif
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// credit @hedgehoginthecpp
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fastfloat_really_inline uint64_t
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convert_4x4_to_16_digits(__m128i data) noexcept {
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// 4. convert to 16-digit number
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// v[0] * 10^12 + v[1] * 10^8 + v[2] * 10^4 + v[3]
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const uint64_t lo = static_cast<uint32_t>(_mm_cvtsi128_si32(data));
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const uint64_t hi =
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static_cast<uint32_t>(_mm_cvtsi128_si32(_mm_srli_si128(data, 4)));
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const uint64_t a = lo * 10000ULL + hi;
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const uint64_t lo2 =
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static_cast<uint32_t>(_mm_cvtsi128_si32(_mm_srli_si128(data, 8)));
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const uint64_t hi2 =
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static_cast<uint32_t>(_mm_cvtsi128_si32(_mm_srli_si128(data, 12)));
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const uint64_t b = lo2 * 10000ULL + hi2;
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return a * 100000000ULL + b;
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}
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#if FASTFLOAT_X86_SIMD >= 42
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// credit @hedgehoginthecpp
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fastfloat_really_inline bool parse_if_16_digits(char const *chars,
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uint64_t &value) noexcept {
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FASTFLOAT_SIMD_DISABLE_WARNINGS
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const __m128i data =
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_mm_loadu_si128(reinterpret_cast<__m128i const *>(chars));
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FASTFLOAT_SIMD_RESTORE_WARNINGS
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/*
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* PCMPxSTRI range comparison.
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*
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* First operand:
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*
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* ['0','9']
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*
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* Second operand:
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*
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* 16 input bytes
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*
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* Negative polarity asks for the first byte which is
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* NOT inside the digit range.
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*/
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const __m128i ranges =
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_mm_setr_epi8('0', '9', 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0);
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const auto numbers =
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_mm_cmpestri(ranges, 2, data, 16,
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_SIDD_UBYTE_OPS | _SIDD_CMP_RANGES |
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_SIDD_NEGATIVE_POLARITY | _SIDD_LEAST_SIGNIFICANT);
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if (numbers != 16)
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return false;
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value = value * 10000000000000000ULL +
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convert_4x4_to_16_digits(parse_4x4_digits(data));
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return true;
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}
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#endif
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#if FASTFLOAT_X86_SIMD >= 31
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// credit @hedgehoginthecpp
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fastfloat_really_inline uint64_t parse_16_digits(char const *p) noexcept {
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const __m128i data = _mm_loadu_si128(reinterpret_cast<const __m128i *>(p));
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return convert_4x4_to_16_digits(parse_4x4_digits(data));
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}
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#endif
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// credit @hedgehoginthecpp
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fastfloat_really_inline FASTFLOAT_CONSTEXPR20 void
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parse_digits_until_19(char const *&p, char const *pend, am_mant_t &mantissa) {
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#if FASTFLOAT_X86_SIMD >= 31
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if (!is_constant_evaluated()) {
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// If mantissa < 10^2, a 16-digit block is guaranteed < 10^18 - 1.
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while (std::distance(p, pend) >= 16 && mantissa < 100) {
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auto const value = parse_16_digits(p);
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mantissa = mantissa * 10000000000000000ULL + value;
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p += 16;
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}
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}
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#endif
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// If mantissa < 10^10, a 8-digit block is guaranteed < 10^18 - 1.
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while (std::distance(p, pend) >= 8 && mantissa < 10000000000ULL) {
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auto const value = parse_8_digits(p);
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mantissa = mantissa * 100000000ULL + value;
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p += 8;
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}
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// If mantissa < 10^12, a 4-digit block is guaranteed < 10^18 - 1.
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if (std::distance(p, pend) >= 4 && mantissa < 1000000000000ULL) {
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auto const value = read_chars_to_unsigned<uint32_t>(p);
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mantissa = mantissa * 10000 + parse_4_digits(value);
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p += 4;
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}
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// If mantissa < 10^19, we should parse digits one by one.
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while (p != pend && mantissa < minimal_nineteen_digit_integer) {
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mantissa = mantissa * 10 + static_cast<uint8_t>(*p - '0');
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++p;
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}
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// While mantissa >= 10^19, we should stop parsing digits.
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}
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template <typename UC, FASTFLOAT_ENABLE_IF(!std::is_same<UC, char>::value) = 0>
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fastfloat_really_inline FASTFLOAT_CONSTEXPR20 void
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parse_digits_until_19(UC const *&p, UC const *pend,
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am_mant_t &mantissa) noexcept {
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do {
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mantissa = mantissa * 10 + static_cast<uint8_t>(*p - UC('0'));
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} while (++p != pend && mantissa < minimal_nineteen_digit_integer);
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}
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#else
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template <typename UC>
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fastfloat_really_inline FASTFLOAT_CONSTEXPR20 void
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parse_digits_until_19(UC const *&p, UC const *pend,
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am_mant_t &mantissa) noexcept {
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do {
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mantissa = mantissa * 10 + static_cast<uint8_t>(*p - UC('0'));
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} while (++p != pend && mantissa < minimal_nineteen_digit_integer);
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}
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#endif
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// Call this if chars might not be 8 digits.
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// Using this style (instead of is_made_of_8_digits() then
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// parse_8_digits()) ensures we don't load SIMD registers twice.
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fastfloat_really_inline FASTFLOAT_CONSTEXPR20 bool
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simd_parse_if_8_digits(char16_t const *chars, uint64_t &i) noexcept {
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if (is_constant_evaluated()) {
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return false;
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}
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#if FASTFLOAT_X86_SIMD
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FASTFLOAT_SIMD_DISABLE_WARNINGS
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// Load 8 UTF-16 characters (16 bytes)
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// unaligned SIMD instruction -> all fine.
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__m128i const data =
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_mm_loadu_si128(reinterpret_cast<__m128i const *>(chars));
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FASTFLOAT_SIMD_RESTORE_WARNINGS
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// Branchless "are all digits?" trick from Lemire:
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// (x - '0') <= 9 <=> (x + 32720) <= 32729
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// encoded as signed comparison: (x + 32720) > -32759 ? not digit : digit
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// http://0x80.pl/articles/simd-parsing-int-sequences.html
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__m128i const t0 = _mm_add_epi16(data, _mm_set1_epi16(32720));
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__m128i const mask = _mm_cmpgt_epi16(t0, _mm_set1_epi16(-32759));
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// If mask == 0 → all digits valid.
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if (_mm_movemask_epi8(mask) == 0) {
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i = i * 100000000 + parse_8_digits(simd_read8(data));
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return true;
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}
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#elif FASTFLOAT_ARM_NEON
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FASTFLOAT_SIMD_DISABLE_WARNINGS
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uint16x8_t const data = vld1q_u16(reinterpret_cast<uint16_t const *>(chars));
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FASTFLOAT_SIMD_RESTORE_WARNINGS
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// (x - '0') <= 9
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// http://0x80.pl/articles/simd-parsing-int-sequences.html
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uint16x8_t const t0 = vsubq_u16(data, vmovq_n_u16('0'));
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uint16x8_t const mask = vcltq_u16(t0, vmovq_n_u16('9' - '0' + 1));
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if (vminvq_u16(mask) == 0xFFFF) {
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i = i * 100000000 + parse_8_digits(simd_read8(data));
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return true;
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}
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#else
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(void)chars;
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(void)i;
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#endif
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return false;
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}
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#else
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template <typename UC>
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fastfloat_really_inline FASTFLOAT_CONSTEXPR20 void
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parse_digits_until_19(UC const *&p, UC const *pend,
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am_mant_t &mantissa) noexcept {
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do {
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mantissa = mantissa * 10 + static_cast<uint8_t>(*p - UC('0'));
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} while (++p != pend && mantissa < minimal_nineteen_digit_integer);
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}
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#endif
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// MSVC SFINAE is broken pre-VS2017
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#if defined(_MSC_VER) && _MSC_VER <= 1900
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template <typename UC>
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#else
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template <typename UC, FASTFLOAT_ENABLE_IF(!has_simd_opt<UC>()) = 0>
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#endif
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// dummy for compiler
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constexpr bool simd_parse_if_8_digits(UC const *, uint64_t &) {
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return false;
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}
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template <typename UC, FASTFLOAT_ENABLE_IF(!std::is_same<UC, char>::value) = 0>
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fastfloat_really_inline FASTFLOAT_CONSTEXPR20 void
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loop_parse_if_digits(UC const *&p, UC const *const pend, uint64_t &i) noexcept {
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if (!is_constant_evaluated()) {
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if FASTFLOAT_CONSTEXPR17 (has_simd_opt<UC>()) {
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while (std::distance(p, pend) >= 8 &&
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simd_parse_if_8_digits(p, i)) { // may overflow, that's ok
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p += 8;
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}
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}
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}
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// Finalizer
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while (p != pend && is_integer(*p)) {
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i = i * 10 + static_cast<uint8_t>(*p - UC('0')); // may overflow, that's ok
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++p;
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}
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}
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fastfloat_really_inline FASTFLOAT_CONSTEXPR20 void
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loop_parse_if_digits(char const *&p, char const *const pend,
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uint64_t &i) noexcept {
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#if FASTFLOAT_USE_SIMD && FASTFLOAT_X86_SIMD >= 42
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if (!is_constant_evaluated()) {
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// SSE4.2 handles 16 bytes at once.
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while (std::distance(p, pend) >= 16)
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if (parse_if_16_digits(p, i)) {
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p += 16;
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} else {
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break;
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}
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}
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#endif
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// Optimizes better than parse_if_eight_digits_unrolled() for char.
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while (std::distance(p, pend) >= 8 /*sizeof(uint64_t)*/) {
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auto const val = read_chars_to_unsigned<uint64_t>(p);
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if (is_made_of_8_digits(val)) {
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i = i * 100000000 + parse_8_digits(val); // may overflow, that's ok
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p += sizeof(uint64_t);
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} else {
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break;
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}
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}
|
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// Consume a remaining 4-7 digit run in a single SWAR step instead of
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// byte-by-byte (reuses the existing 4-digit helpers). The parsed result is
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||
// identical either way. Historically gated to clang because gcc regressed on
|
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// short remainders, but that verdict predates the span-elision restructure;
|
||
// with the leaner hot path the 4-digit step now wins on gcc as well.
|
||
if (std::distance(p, pend) >= 4 /*sizeof(uint32_t)*/) {
|
||
auto const val = read_chars_to_unsigned<uint32_t>(p);
|
||
if (is_made_of_4_digits(val)) {
|
||
i = i * 10000 + parse_4_digits(val); // may overflow, that's ok
|
||
p += sizeof(uint32_t);
|
||
}
|
||
}
|
||
// Finalizer
|
||
while (p != pend && is_integer(*p)) {
|
||
i = i * 10 + static_cast<uint8_t>(*p - '0'); // may overflow, that's ok
|
||
++p;
|
||
}
|
||
}
|
||
|
||
enum class parse_error : uint_fast8_t {
|
||
no_error,
|
||
// A sign must be followed by an integer or dot.
|
||
missing_integer_or_dot_after_sign,
|
||
// The mantissa must have at least one digit.
|
||
no_digits_in_mantissa,
|
||
// Scientific notation requires an exponential part.
|
||
missing_exponential_part,
|
||
#ifndef FASTFLOAT_ONLY_POSITIVE_C_NUMBER_WO_INF_NAN
|
||
// [JavaScript-only, sloppy mode] The integer part is a legacy octal literal
|
||
// (a leading zero followed by octal digits only), which is not a decimal
|
||
// number. Parse it in base 8 instead.
|
||
legacy_octal_integer_part,
|
||
// [JSON/JavaScript-only] The integer part must not have leading zeros.
|
||
leading_zeros_in_integer_part,
|
||
// [JSON-only] The minus sign must be followed by an integer.
|
||
missing_integer_after_sign,
|
||
// [JSON-only] The integer part must have at least one digit.
|
||
no_digits_in_integer_part,
|
||
// [JSON-only] If there is a decimal point, there must be digits in the
|
||
// fractional part.
|
||
no_digits_in_fractional_part,
|
||
#endif
|
||
};
|
||
|
||
template <typename UC> struct parsed_number_string_t {
|
||
FASTFLOAT_NO_UNIQUE_ADDRESS UC const *lastmatch;
|
||
FASTFLOAT_NO_UNIQUE_ADDRESS am_mant_t mantissa;
|
||
FASTFLOAT_NO_UNIQUE_ADDRESS am_pow_t exponent;
|
||
|
||
FASTFLOAT_NO_UNIQUE_ADDRESS parse_error error;
|
||
#ifndef FASTFLOAT_ONLY_POSITIVE_C_NUMBER_WO_INF_NAN
|
||
FASTFLOAT_NO_UNIQUE_ADDRESS bool negative;
|
||
#endif
|
||
FASTFLOAT_NO_UNIQUE_ADDRESS bool invalid;
|
||
FASTFLOAT_NO_UNIQUE_ADDRESS bool too_many_digits;
|
||
|
||
// contains the range of the significant digits, fully optional, only matters
|
||
// if it's length > 0
|
||
FASTFLOAT_NO_UNIQUE_ADDRESS span<UC const> integer;
|
||
FASTFLOAT_NO_UNIQUE_ADDRESS span<UC const> fraction;
|
||
};
|
||
|
||
using byte_span = span<char const>;
|
||
using parsed_number_string = parsed_number_string_t<char>;
|
||
|
||
// Helper for error creating
|
||
template <typename UC>
|
||
fastfloat_really_inline FASTFLOAT_CONSTEXPR20 parsed_number_string_t<UC> &
|
||
report_parse_error(parsed_number_string_t<UC> &answer, UC const *p,
|
||
parse_error error) noexcept {
|
||
answer.invalid = true;
|
||
answer.lastmatch = p;
|
||
answer.error = error;
|
||
return answer;
|
||
}
|
||
|
||
// Assuming that you use no more than 19 digits, this will
|
||
// parse an ASCII string.
|
||
//
|
||
// store_spans is a *runtime* flag (not a template parameter, deliberately: a
|
||
// template would create a second instantiation of this whole function and the
|
||
// extra icache pressure wipes out the gain). When false, the integer/fraction
|
||
// spans (read only by the rare digit_comp slow path) are not materialized,
|
||
// which keeps the fat parsed_number_string_t off the hot path. The caller
|
||
// re-parses with store_spans=true if the slow path is actually reached.
|
||
template <bool json_fmt, typename UC>
|
||
fastfloat_really_inline FASTFLOAT_CONSTEXPR20 parsed_number_string_t<UC>
|
||
parse_number_string(UC const *p, UC const *pend,
|
||
parse_options_t<UC> const options,
|
||
bool store_spans = true) noexcept {
|
||
parsed_number_string_t<UC> answer{};
|
||
FASTFLOAT_ASSUME(p < pend); // so dereference without checks
|
||
#ifndef FASTFLOAT_ONLY_POSITIVE_C_NUMBER_WO_INF_NAN
|
||
answer.negative = *p == UC('-');
|
||
// C++17 20.19.3.(7.1) explicitly forbids '+' sign here
|
||
if (answer.negative ||
|
||
(!json_fmt &&
|
||
chars_format_t(options.format & chars_format::allow_leading_plus) &&
|
||
*p == UC('+'))) {
|
||
++p;
|
||
|
||
if (json_fmt) {
|
||
if (p == pend &&
|
||
!is_integer(*p)) { // A sign must be followed by an integer
|
||
return report_parse_error<UC>(answer, p,
|
||
parse_error::missing_integer_after_sign);
|
||
}
|
||
} else {
|
||
if (p == pend && !is_integer(*p) && *p != options.decimal_point) {
|
||
// A sign must be followed by an integer or the dot
|
||
return report_parse_error<UC>(
|
||
answer, p, parse_error::missing_integer_or_dot_after_sign);
|
||
}
|
||
}
|
||
}
|
||
#endif
|
||
auto const *const start_digits = p;
|
||
|
||
// HedgehogInTheCPP: compiler generate much better code in any mode without
|
||
// manual unroling because it's less branching and also it's allow more
|
||
// inlining which is better. A a multiplication by 10 is cheaper than an
|
||
// arbitrary integer multiplication. might overflow, handled later
|
||
#if !defined(FASTFLOAT_ISNOT_CHECKED_BOUNDS) && \
|
||
!defined(FASTFLOAT_ONLY_POSITIVE_C_NUMBER_WO_INF_NAN)
|
||
while (p != pend && is_integer(*p)) {
|
||
answer.mantissa = static_cast<fast_float::am_mant_t>(
|
||
answer.mantissa * 10 + static_cast<uint8_t>(*p - UC('0')));
|
||
++p;
|
||
}
|
||
#else
|
||
// External parser already check that this is num and it's exist
|
||
do {
|
||
answer.mantissa = static_cast<fast_float::am_mant_t>(
|
||
answer.mantissa * 10 + static_cast<uint8_t>(*p - UC('0')));
|
||
++p;
|
||
} while (p != pend && is_integer(*p));
|
||
#endif
|
||
UC const *const end_of_integer_part = p;
|
||
auto digit_count = static_cast<am_digits>(end_of_integer_part - start_digits);
|
||
if fastfloat_unlikely (store_spans) {
|
||
answer.integer = span<UC const>(start_digits, digit_count);
|
||
}
|
||
#ifndef FASTFLOAT_ONLY_POSITIVE_C_NUMBER_WO_INF_NAN
|
||
if (json_fmt) {
|
||
// At least 1 digit in integer part
|
||
if (digit_count == 0) {
|
||
return report_parse_error<UC>(answer, p,
|
||
parse_error::no_digits_in_integer_part);
|
||
}
|
||
}
|
||
if (json_fmt || chars_format_t(options.format & detail::javascript_fmt)) {
|
||
// ECMAScript DecimalIntegerLiteral is "0" or a non-zero digit followed by
|
||
// digits: no leading zeros. Unlike JSON, the integer part may be empty
|
||
// (".5"); the no_digits_in_mantissa check below still rejects ".".
|
||
if (start_digits[0] == UC('0') && digit_count > 1) {
|
||
if (json_fmt ||
|
||
!chars_format_t(options.format & detail::javascript_sloppy_fmt)) {
|
||
return report_parse_error<UC>(
|
||
answer, start_digits, parse_error::leading_zeros_in_integer_part);
|
||
}
|
||
if (!json_fmt) {
|
||
// Sloppy mode (Annex B): a NonOctalDecimalIntegerLiteral has a leading
|
||
// zero and at least one digit that is 8 or 9 ("08.5" is 8.5). With
|
||
// octal digits only, it is a LegacyOctalIntegerLiteral ("0775"), which
|
||
// is not a decimal number: report it so the caller can parse it in
|
||
// base 8.
|
||
bool has_non_octal_digit = false;
|
||
for (UC const *q = start_digits; q != end_of_integer_part; ++q) {
|
||
has_non_octal_digit |= (*q >= UC('8'));
|
||
}
|
||
if (!has_non_octal_digit) {
|
||
return report_parse_error<UC>(answer, start_digits,
|
||
parse_error::legacy_octal_integer_part);
|
||
}
|
||
}
|
||
}
|
||
}
|
||
#endif
|
||
|
||
// We can now parse the fraction part of the mantissa.
|
||
bool const has_decimal_point = p != pend && *p == options.decimal_point;
|
||
if (has_decimal_point) {
|
||
++p;
|
||
auto const *const before = p;
|
||
// can occur at most twice without overflowing, but let it occur more, since
|
||
// for integers with many digits, digit parsing is the primary bottleneck.
|
||
loop_parse_if_digits(p, pend, answer.mantissa);
|
||
|
||
answer.exponent = static_cast<am_pow_t>(before - p);
|
||
if fastfloat_unlikely (store_spans) {
|
||
answer.fraction =
|
||
span<UC const>(before, static_cast<am_digits>(p - before));
|
||
}
|
||
digit_count -= static_cast<am_digits>(answer.exponent);
|
||
}
|
||
#ifndef FASTFLOAT_ONLY_POSITIVE_C_NUMBER_WO_INF_NAN
|
||
if (json_fmt) {
|
||
// At least 1 digit in fractional part
|
||
if (has_decimal_point && answer.exponent == 0) {
|
||
return report_parse_error<UC>(answer, p,
|
||
parse_error::no_digits_in_fractional_part);
|
||
}
|
||
} else
|
||
#endif
|
||
if (digit_count == 0) { // We must have encountered at least one integer!
|
||
return report_parse_error<UC>(answer, p,
|
||
parse_error::no_digits_in_mantissa);
|
||
}
|
||
// We have now parsed the integer and the fraction part of the mantissa.
|
||
|
||
// Now we can parse the explicit exponential part.
|
||
am_pow_t exp_number = 0; // explicit exponential part
|
||
if (p != pend &&
|
||
((chars_format_t(options.format & chars_format::scientific) &&
|
||
(UC('e') == *p || UC('E') == *p))
|
||
#ifndef FASTFLOAT_ONLY_POSITIVE_C_NUMBER_WO_INF_NAN
|
||
|| (chars_format_t(options.format & detail::fortran_fmt) &&
|
||
(UC('+') == *p || UC('-') == *p || UC('d') == *p || UC('D') == *p))
|
||
#endif
|
||
)) {
|
||
auto const *location_of_e = p;
|
||
#ifndef FASTFLOAT_ONLY_POSITIVE_C_NUMBER_WO_INF_NAN
|
||
if (UC('e') == *p || UC('E') == *p || UC('d') == *p || UC('D') == *p) {
|
||
++p;
|
||
}
|
||
#else
|
||
++p;
|
||
#endif
|
||
bool neg_exp = false;
|
||
if (p != pend) {
|
||
if (UC('-') == *p) {
|
||
neg_exp = true;
|
||
++p;
|
||
} else if (UC('+') == *p) {
|
||
// '+' on exponent is allowed by C++17 20.19.3.(7.1)
|
||
++p;
|
||
}
|
||
}
|
||
// We have now parsed the sign of the exponent.
|
||
if (p == pend || !is_integer(*p)) {
|
||
if (!chars_format_t(options.format & chars_format::fixed)) {
|
||
// The exponential part is invalid for scientific notation, so it must
|
||
// be a trailing token for fixed notation. However, fixed notation is
|
||
// disabled, so report a scientific notation error.
|
||
return report_parse_error<UC>(answer, p,
|
||
parse_error::missing_exponential_part);
|
||
}
|
||
// Otherwise, we will be ignoring the 'e'.
|
||
p = location_of_e;
|
||
} else {
|
||
// Now let's parse the explicit exponent.
|
||
while (p != pend && is_integer(*p)) {
|
||
if (exp_number < am_bias_limit) {
|
||
// check for exponent overflow if we have too many digits.
|
||
auto const digit = static_cast<uint8_t>(*p - UC('0'));
|
||
exp_number = 10 * exp_number + digit;
|
||
}
|
||
++p;
|
||
}
|
||
if (neg_exp) {
|
||
exp_number = -exp_number;
|
||
}
|
||
answer.exponent += exp_number;
|
||
}
|
||
} else {
|
||
// If it scientific and not fixed, we have to bail out.
|
||
if (chars_format_t(options.format & chars_format::scientific) &&
|
||
!chars_format_t(options.format & chars_format::fixed)) {
|
||
return report_parse_error<UC>(answer, p,
|
||
parse_error::missing_exponential_part);
|
||
}
|
||
}
|
||
|
||
// We sucessfully parsed all parts of the number, let's save progress.
|
||
answer.lastmatch = p;
|
||
|
||
// Now we can check for errors.
|
||
|
||
// If we frequently had to deal with long strings of digits,
|
||
// we could extend our code by using a 128-bit integer instead
|
||
// of a 64-bit integer. However, this is uncommon.
|
||
//
|
||
// We can deal with up to 19 digits.
|
||
if (digit_count > 19) {
|
||
// It is possible that the integer had an overflow.
|
||
// We have to handle the case where we have 0.0000somenumber.
|
||
// We need to be mindful of the case where we only have zeroes...
|
||
// E.g., 0.000000000...000.
|
||
auto const *start = start_digits;
|
||
do {
|
||
if (*start == UC('0')) {
|
||
--digit_count;
|
||
} else if (*start != options.decimal_point) {
|
||
break;
|
||
}
|
||
} while (++start != pend);
|
||
|
||
// We have to check if number has more than 19 significant digits.
|
||
if (digit_count > 19) {
|
||
answer.too_many_digits = true;
|
||
// The truncation recompute below reads the integer/fraction spans. When
|
||
// store_spans is false we didn't materialize them, so just flag
|
||
// too_many_digits; the caller re-parses with store_spans=true to obtain
|
||
// the corrected mantissa/exponent before taking the slow path.
|
||
if fastfloat_unlikely (store_spans) {
|
||
// Let us start again, this time, avoiding overflows.
|
||
// We don't need to call if is_integer, since we use the
|
||
// pre-tokenized spans from above.
|
||
answer.mantissa = 0;
|
||
p = answer.integer.ptr;
|
||
parse_digits_until_19(p, p + answer.integer.len(), answer.mantissa);
|
||
if (answer.mantissa >= minimal_nineteen_digit_integer) {
|
||
// We have a big integers, so skip the fraction part completely.
|
||
answer.exponent = am_pow_t(end_of_integer_part - p) + exp_number;
|
||
} else if (answer.fraction.len()) {
|
||
// We have a value with a significant fractional component.
|
||
p = answer.fraction.ptr;
|
||
parse_digits_until_19(p, p + answer.fraction.len(), answer.mantissa);
|
||
answer.exponent = am_pow_t(answer.fraction.ptr - p) + exp_number;
|
||
}
|
||
// We have now corrected both exponent and mantissa, to a truncated
|
||
// value
|
||
}
|
||
}
|
||
}
|
||
|
||
return answer;
|
||
}
|
||
|
||
template <typename T, typename UC>
|
||
fastfloat_really_inline FASTFLOAT_CONSTEXPR20 from_chars_result_t<UC>
|
||
parse_int_string(UC const *p, UC const *pend, T &value,
|
||
parse_options_t<UC> const options) noexcept {
|
||
FASTFLOAT_ASSUME(p < pend); // so dereference without checks
|
||
from_chars_result_t<UC> answer;
|
||
|
||
#ifndef FASTFLOAT_ONLY_POSITIVE_C_NUMBER_WO_INF_NAN
|
||
auto const *const first = p;
|
||
// Read sign
|
||
auto const negative = (*p == UC('-'));
|
||
#ifdef FASTFLOAT_VISUAL_STUDIO
|
||
#pragma warning(push)
|
||
#pragma warning(disable : 4127)
|
||
#endif
|
||
if (!std::is_signed<T>::value && negative) {
|
||
#ifdef FASTFLOAT_VISUAL_STUDIO
|
||
#pragma warning(pop)
|
||
#endif
|
||
answer.ec = std::errc::invalid_argument;
|
||
answer.ptr = first;
|
||
return answer;
|
||
}
|
||
if (negative ||
|
||
(chars_format_t(options.format & chars_format::allow_leading_plus) &&
|
||
(*p == UC('+')))) {
|
||
++p;
|
||
}
|
||
#endif
|
||
|
||
auto const *const start_num = p;
|
||
|
||
// Skip leading zeros
|
||
#if !defined(FASTFLOAT_ISNOT_CHECKED_BOUNDS) && \
|
||
!defined(FASTFLOAT_ONLY_POSITIVE_C_NUMBER_WO_INF_NAN)
|
||
while (p != pend && *p == UC('0')) {
|
||
++p;
|
||
}
|
||
#else
|
||
// External parser already check that this is num and it's exist
|
||
do {
|
||
if (*p == UC('0')) {
|
||
++p;
|
||
} else {
|
||
break;
|
||
}
|
||
} while (p != pend);
|
||
#endif
|
||
auto const has_leading_zeros = p > start_num;
|
||
|
||
auto const *const start_digits = p;
|
||
|
||
if (options.base == 10) {
|
||
auto const len = static_cast<am_digits>(pend - p);
|
||
#ifndef FASTFLOAT_ISNOT_CHECKED_BOUNDS
|
||
// External parser already check that this is num and it's exist
|
||
if (len == 0) {
|
||
#endif
|
||
if (has_leading_zeros) {
|
||
value = 0;
|
||
answer.ec = std::errc();
|
||
answer.ptr = p;
|
||
return answer;
|
||
}
|
||
#ifndef FASTFLOAT_ISNOT_CHECKED_BOUNDS
|
||
answer.ec = std::errc::invalid_argument;
|
||
answer.ptr = first;
|
||
return answer;
|
||
}
|
||
#endif
|
||
|
||
if FASTFLOAT_CONSTEXPR17 (std::is_same<T, std::uint8_t>::value &&
|
||
sizeof(UC) == 1) {
|
||
uint32_t digits;
|
||
|
||
if (len >= sizeof(uint32_t)) {
|
||
digits = read_chars_to_unsigned<uint32_t>(p);
|
||
} else {
|
||
uint32_t const b0 = static_cast<uint8_t>(p[0]);
|
||
uint32_t const b1 = (len > 1) ? static_cast<uint8_t>(p[1]) : 0x00u;
|
||
uint32_t const b2 = (len > 2) ? static_cast<uint8_t>(p[2]) : 0x00u;
|
||
uint32_t const b3 = 0x00u;
|
||
digits = b0 | (b1 << 8) | (b2 << 16) | (b3 << 24);
|
||
}
|
||
|
||
uint32_t const magic =
|
||
((digits + 0x46464646u) | (digits - 0x30303030u)) & 0x80808080u;
|
||
auto const tz = countr_zero_32(magic); // 7, 15, 23, 31, or 32
|
||
auto nd = static_cast<am_digits>(tz >> 3);
|
||
nd = nd < len ? nd : len;
|
||
#ifndef FASTFLOAT_ISNOT_CHECKED_BOUNDS
|
||
// External parser already check that this is num and it's exist
|
||
if (nd == 0) {
|
||
#endif
|
||
if (has_leading_zeros) {
|
||
value = 0;
|
||
answer.ec = std::errc();
|
||
answer.ptr = p;
|
||
return answer;
|
||
}
|
||
#ifndef FASTFLOAT_ISNOT_CHECKED_BOUNDS
|
||
answer.ec = std::errc::invalid_argument;
|
||
answer.ptr = first;
|
||
return answer;
|
||
}
|
||
#endif
|
||
if (nd > 3) {
|
||
const UC *q = p + nd;
|
||
am_digits rem = len - nd;
|
||
while (rem) {
|
||
if (*q < UC('0') || *q > UC('9')) {
|
||
break;
|
||
}
|
||
++q;
|
||
--rem;
|
||
}
|
||
answer.ec = std::errc::result_out_of_range;
|
||
answer.ptr = q;
|
||
return answer;
|
||
}
|
||
|
||
digits ^= 0x30303030u;
|
||
digits <<= ((4 - nd) * 8);
|
||
|
||
uint32_t const check = ((digits >> 24) & 0xff) |
|
||
((digits >> 8) & 0xff00) |
|
||
((digits << 8) & 0xff0000);
|
||
if (check > 0x00020505) {
|
||
answer.ec = std::errc::result_out_of_range;
|
||
answer.ptr = p + nd;
|
||
return answer;
|
||
}
|
||
value = static_cast<uint8_t>((0x640a01 * digits) >> 24);
|
||
answer.ec = std::errc();
|
||
answer.ptr = p + nd;
|
||
return answer;
|
||
}
|
||
|
||
if FASTFLOAT_CONSTEXPR17 (std::is_same<T, std::uint16_t>::value &&
|
||
sizeof(UC) == 1) {
|
||
if (len >= sizeof(uint32_t)) {
|
||
auto const digits = read_chars_to_unsigned<uint32_t>(p);
|
||
if (is_made_of_4_digits(digits)) {
|
||
auto v = parse_4_digits(digits);
|
||
if (len >= 5 && is_integer(p[4])) {
|
||
v = v * 10 + static_cast<uint8_t>(p[4] - '0');
|
||
if (len >= 6 && is_integer(p[5])) {
|
||
const UC *q = p + 5;
|
||
while (q != pend && is_integer(*q)) {
|
||
++q;
|
||
}
|
||
answer.ec = std::errc::result_out_of_range;
|
||
answer.ptr = q;
|
||
return answer;
|
||
}
|
||
if (v > std::numeric_limits<uint16_t>::max()) {
|
||
answer.ec = std::errc::result_out_of_range;
|
||
answer.ptr = p + 5;
|
||
return answer;
|
||
}
|
||
value = static_cast<uint16_t>(v);
|
||
answer.ec = std::errc();
|
||
answer.ptr = p + 5;
|
||
return answer;
|
||
}
|
||
// 4 digits
|
||
value = static_cast<uint16_t>(v);
|
||
answer.ec = std::errc();
|
||
answer.ptr = p + 4;
|
||
return answer;
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
// Parse digits
|
||
am_mant_t i = 0;
|
||
if (options.base == 10) {
|
||
loop_parse_if_digits(p, pend, i); // use SIMD if possible
|
||
} else
|
||
while (p != pend) {
|
||
auto const digit = ch_to_digit(*p);
|
||
if (digit >= options.base) {
|
||
break;
|
||
}
|
||
i = am_mant_t(options.base) * i +
|
||
digit; // might overflow, check this later
|
||
++p;
|
||
}
|
||
|
||
auto const digit_count = static_cast<am_digits>(p - start_digits);
|
||
|
||
#ifndef FASTFLOAT_ISNOT_CHECKED_BOUNDS
|
||
// parser already check that this is num and it's exist
|
||
if (digit_count == 0) {
|
||
#endif
|
||
if (has_leading_zeros) {
|
||
value = 0;
|
||
answer.ec = std::errc();
|
||
answer.ptr = p;
|
||
return answer;
|
||
}
|
||
#ifndef FASTFLOAT_ISNOT_CHECKED_BOUNDS
|
||
answer.ec = std::errc::invalid_argument;
|
||
answer.ptr = first;
|
||
|
||
return answer;
|
||
}
|
||
#endif
|
||
|
||
answer.ptr = p;
|
||
|
||
// check u64 overflow
|
||
auto const max_digits = max_digits_u64(options.base);
|
||
if (digit_count > max_digits) {
|
||
answer.ec = std::errc::result_out_of_range;
|
||
return answer;
|
||
}
|
||
// this check can be eliminated for all other types, but they will all require
|
||
// a max_digits(base) equivalent
|
||
if (digit_count == max_digits) {
|
||
// At the max_digits boundary the accumulator `i` may have wrapped around
|
||
// 2^64. A plain `i < min_safe_u64(base)` test is not sufficient: for any
|
||
// base whose max_digits-length range exceeds 2^64 (base 10 reaches
|
||
// ~5.4 * 2^64 at 20 digits) the value can wrap a whole multiple of 2^64 and
|
||
// land back above min_safe, slipping through. Decide exactly in O(1) using
|
||
// the leading digit, following the approach used in simdjson:
|
||
// ms == min_safe_u64(base) == base^(max_digits-1), the smallest
|
||
// max_digits-length value.
|
||
// dmax == the largest leading digit whose number can still fit in u64.
|
||
// The leading-digit band [d*ms, (d+1)*ms) has width ms < 2^64, so within
|
||
// the single band where d == dmax the value straddles 2^64 at most once,
|
||
// and a single threshold separates wrapped from non-wrapped values. A
|
||
// leading digit above dmax always overflows; below dmax always fits.
|
||
uint64_t const ms = min_safe_u64(options.base);
|
||
uint64_t const dmax = std::numeric_limits<uint64_t>::max() / ms;
|
||
uint64_t const lead = ch_to_digit(*start_digits);
|
||
if (lead > dmax || (lead == dmax && i < dmax * ms)) {
|
||
answer.ec = std::errc::result_out_of_range;
|
||
return answer;
|
||
}
|
||
}
|
||
|
||
// check other types overflow
|
||
if (!std::is_same<T, am_mant_t>::value) {
|
||
if (i > am_mant_t(std::numeric_limits<T>::max())
|
||
#ifndef FASTFLOAT_ONLY_POSITIVE_C_NUMBER_WO_INF_NAN
|
||
+ uint8_t(negative)
|
||
#endif
|
||
) {
|
||
answer.ec = std::errc::result_out_of_range;
|
||
return answer;
|
||
}
|
||
}
|
||
|
||
#ifdef FASTFLOAT_ONLY_POSITIVE_C_NUMBER_WO_INF_NAN
|
||
value = T(i);
|
||
#else
|
||
if (negative) {
|
||
#ifdef FASTFLOAT_VISUAL_STUDIO
|
||
#pragma warning(push)
|
||
#pragma warning(disable : 4146)
|
||
#pragma warning(disable : 4804)
|
||
#endif
|
||
// this weird workaround is required because:
|
||
// - converting unsigned to signed when its value is greater than signed max
|
||
// is UB pre-C++23.
|
||
// - reinterpret_casting (~i + 1) would work, but it is not constexpr
|
||
// this is always optimized into a neg instruction (note: T is an integer
|
||
// type)
|
||
value = T(-std::numeric_limits<T>::max() -
|
||
T(i - am_mant_t(std::numeric_limits<T>::max())));
|
||
#ifdef FASTFLOAT_VISUAL_STUDIO
|
||
#pragma warning(pop)
|
||
#endif
|
||
} else {
|
||
value = T(i);
|
||
}
|
||
#endif
|
||
|
||
answer.ec = std::errc();
|
||
return answer;
|
||
}
|
||
|
||
} // namespace fast_float
|
||
|
||
#endif
|