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Diffstat (limited to 'third_party/abseil_cpp/absl/strings/numbers.cc')
| -rw-r--r-- | third_party/abseil_cpp/absl/strings/numbers.cc | 965 |
1 files changed, 0 insertions, 965 deletions
diff --git a/third_party/abseil_cpp/absl/strings/numbers.cc b/third_party/abseil_cpp/absl/strings/numbers.cc deleted file mode 100644 index 68c26dd6f8..0000000000 --- a/third_party/abseil_cpp/absl/strings/numbers.cc +++ /dev/null @@ -1,965 +0,0 @@ -// Copyright 2017 The Abseil Authors. -// -// Licensed under the Apache License, Version 2.0 (the "License"); -// you may not use this file except in compliance with the License. -// You may obtain a copy of the License at -// -// https://www.apache.org/licenses/LICENSE-2.0 -// -// Unless required by applicable law or agreed to in writing, software -// distributed under the License is distributed on an "AS IS" BASIS, -// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. -// See the License for the specific language governing permissions and -// limitations under the License. - -// This file contains string processing functions related to -// numeric values. - -#include "absl/strings/numbers.h" - -#include <algorithm> -#include <cassert> -#include <cfloat> // for DBL_DIG and FLT_DIG -#include <cmath> // for HUGE_VAL -#include <cstdint> -#include <cstdio> -#include <cstdlib> -#include <cstring> -#include <iterator> -#include <limits> -#include <memory> -#include <utility> - -#include "absl/base/attributes.h" -#include "absl/base/internal/bits.h" -#include "absl/base/internal/raw_logging.h" -#include "absl/strings/ascii.h" -#include "absl/strings/charconv.h" -#include "absl/strings/escaping.h" -#include "absl/strings/internal/memutil.h" -#include "absl/strings/match.h" -#include "absl/strings/str_cat.h" - -namespace absl { -ABSL_NAMESPACE_BEGIN - -bool SimpleAtof(absl::string_view str, float* out) { - *out = 0.0; - str = StripAsciiWhitespace(str); - if (!str.empty() && str[0] == '+') { - str.remove_prefix(1); - } - auto result = absl::from_chars(str.data(), str.data() + str.size(), *out); - if (result.ec == std::errc::invalid_argument) { - return false; - } - if (result.ptr != str.data() + str.size()) { - // not all non-whitespace characters consumed - return false; - } - // from_chars() with DR 3081's current wording will return max() on - // overflow. SimpleAtof returns infinity instead. - if (result.ec == std::errc::result_out_of_range) { - if (*out > 1.0) { - *out = std::numeric_limits<float>::infinity(); - } else if (*out < -1.0) { - *out = -std::numeric_limits<float>::infinity(); - } - } - return true; -} - -bool SimpleAtod(absl::string_view str, double* out) { - *out = 0.0; - str = StripAsciiWhitespace(str); - if (!str.empty() && str[0] == '+') { - str.remove_prefix(1); - } - auto result = absl::from_chars(str.data(), str.data() + str.size(), *out); - if (result.ec == std::errc::invalid_argument) { - return false; - } - if (result.ptr != str.data() + str.size()) { - // not all non-whitespace characters consumed - return false; - } - // from_chars() with DR 3081's current wording will return max() on - // overflow. SimpleAtod returns infinity instead. - if (result.ec == std::errc::result_out_of_range) { - if (*out > 1.0) { - *out = std::numeric_limits<double>::infinity(); - } else if (*out < -1.0) { - *out = -std::numeric_limits<double>::infinity(); - } - } - return true; -} - -bool SimpleAtob(absl::string_view str, bool* out) { - ABSL_RAW_CHECK(out != nullptr, "Output pointer must not be nullptr."); - if (EqualsIgnoreCase(str, "true") || EqualsIgnoreCase(str, "t") || - EqualsIgnoreCase(str, "yes") || EqualsIgnoreCase(str, "y") || - EqualsIgnoreCase(str, "1")) { - *out = true; - return true; - } - if (EqualsIgnoreCase(str, "false") || EqualsIgnoreCase(str, "f") || - EqualsIgnoreCase(str, "no") || EqualsIgnoreCase(str, "n") || - EqualsIgnoreCase(str, "0")) { - *out = false; - return true; - } - return false; -} - -// ---------------------------------------------------------------------- -// FastIntToBuffer() overloads -// -// Like the Fast*ToBuffer() functions above, these are intended for speed. -// Unlike the Fast*ToBuffer() functions, however, these functions write -// their output to the beginning of the buffer. The caller is responsible -// for ensuring that the buffer has enough space to hold the output. -// -// Returns a pointer to the end of the string (i.e. the null character -// terminating the string). -// ---------------------------------------------------------------------- - -namespace { - -// Used to optimize printing a decimal number's final digit. -const char one_ASCII_final_digits[10][2] { - {'0', 0}, {'1', 0}, {'2', 0}, {'3', 0}, {'4', 0}, - {'5', 0}, {'6', 0}, {'7', 0}, {'8', 0}, {'9', 0}, -}; - -} // namespace - -char* numbers_internal::FastIntToBuffer(uint32_t i, char* buffer) { - uint32_t digits; - // The idea of this implementation is to trim the number of divides to as few - // as possible, and also reducing memory stores and branches, by going in - // steps of two digits at a time rather than one whenever possible. - // The huge-number case is first, in the hopes that the compiler will output - // that case in one branch-free block of code, and only output conditional - // branches into it from below. - if (i >= 1000000000) { // >= 1,000,000,000 - digits = i / 100000000; // 100,000,000 - i -= digits * 100000000; - PutTwoDigits(digits, buffer); - buffer += 2; - lt100_000_000: - digits = i / 1000000; // 1,000,000 - i -= digits * 1000000; - PutTwoDigits(digits, buffer); - buffer += 2; - lt1_000_000: - digits = i / 10000; // 10,000 - i -= digits * 10000; - PutTwoDigits(digits, buffer); - buffer += 2; - lt10_000: - digits = i / 100; - i -= digits * 100; - PutTwoDigits(digits, buffer); - buffer += 2; - lt100: - digits = i; - PutTwoDigits(digits, buffer); - buffer += 2; - *buffer = 0; - return buffer; - } - - if (i < 100) { - digits = i; - if (i >= 10) goto lt100; - memcpy(buffer, one_ASCII_final_digits[i], 2); - return buffer + 1; - } - if (i < 10000) { // 10,000 - if (i >= 1000) goto lt10_000; - digits = i / 100; - i -= digits * 100; - *buffer++ = '0' + digits; - goto lt100; - } - if (i < 1000000) { // 1,000,000 - if (i >= 100000) goto lt1_000_000; - digits = i / 10000; // 10,000 - i -= digits * 10000; - *buffer++ = '0' + digits; - goto lt10_000; - } - if (i < 100000000) { // 100,000,000 - if (i >= 10000000) goto lt100_000_000; - digits = i / 1000000; // 1,000,000 - i -= digits * 1000000; - *buffer++ = '0' + digits; - goto lt1_000_000; - } - // we already know that i < 1,000,000,000 - digits = i / 100000000; // 100,000,000 - i -= digits * 100000000; - *buffer++ = '0' + digits; - goto lt100_000_000; -} - -char* numbers_internal::FastIntToBuffer(int32_t i, char* buffer) { - uint32_t u = i; - if (i < 0) { - *buffer++ = '-'; - // We need to do the negation in modular (i.e., "unsigned") - // arithmetic; MSVC++ apprently warns for plain "-u", so - // we write the equivalent expression "0 - u" instead. - u = 0 - u; - } - return numbers_internal::FastIntToBuffer(u, buffer); -} - -char* numbers_internal::FastIntToBuffer(uint64_t i, char* buffer) { - uint32_t u32 = static_cast<uint32_t>(i); - if (u32 == i) return numbers_internal::FastIntToBuffer(u32, buffer); - - // Here we know i has at least 10 decimal digits. - uint64_t top_1to11 = i / 1000000000; - u32 = static_cast<uint32_t>(i - top_1to11 * 1000000000); - uint32_t top_1to11_32 = static_cast<uint32_t>(top_1to11); - - if (top_1to11_32 == top_1to11) { - buffer = numbers_internal::FastIntToBuffer(top_1to11_32, buffer); - } else { - // top_1to11 has more than 32 bits too; print it in two steps. - uint32_t top_8to9 = static_cast<uint32_t>(top_1to11 / 100); - uint32_t mid_2 = static_cast<uint32_t>(top_1to11 - top_8to9 * 100); - buffer = numbers_internal::FastIntToBuffer(top_8to9, buffer); - PutTwoDigits(mid_2, buffer); - buffer += 2; - } - - // We have only 9 digits now, again the maximum uint32_t can handle fully. - uint32_t digits = u32 / 10000000; // 10,000,000 - u32 -= digits * 10000000; - PutTwoDigits(digits, buffer); - buffer += 2; - digits = u32 / 100000; // 100,000 - u32 -= digits * 100000; - PutTwoDigits(digits, buffer); - buffer += 2; - digits = u32 / 1000; // 1,000 - u32 -= digits * 1000; - PutTwoDigits(digits, buffer); - buffer += 2; - digits = u32 / 10; - u32 -= digits * 10; - PutTwoDigits(digits, buffer); - buffer += 2; - memcpy(buffer, one_ASCII_final_digits[u32], 2); - return buffer + 1; -} - -char* numbers_internal::FastIntToBuffer(int64_t i, char* buffer) { - uint64_t u = i; - if (i < 0) { - *buffer++ = '-'; - u = 0 - u; - } - return numbers_internal::FastIntToBuffer(u, buffer); -} - -// Given a 128-bit number expressed as a pair of uint64_t, high half first, -// return that number multiplied by the given 32-bit value. If the result is -// too large to fit in a 128-bit number, divide it by 2 until it fits. -static std::pair<uint64_t, uint64_t> Mul32(std::pair<uint64_t, uint64_t> num, - uint32_t mul) { - uint64_t bits0_31 = num.second & 0xFFFFFFFF; - uint64_t bits32_63 = num.second >> 32; - uint64_t bits64_95 = num.first & 0xFFFFFFFF; - uint64_t bits96_127 = num.first >> 32; - - // The picture so far: each of these 64-bit values has only the lower 32 bits - // filled in. - // bits96_127: [ 00000000 xxxxxxxx ] - // bits64_95: [ 00000000 xxxxxxxx ] - // bits32_63: [ 00000000 xxxxxxxx ] - // bits0_31: [ 00000000 xxxxxxxx ] - - bits0_31 *= mul; - bits32_63 *= mul; - bits64_95 *= mul; - bits96_127 *= mul; - - // Now the top halves may also have value, though all 64 of their bits will - // never be set at the same time, since they are a result of a 32x32 bit - // multiply. This makes the carry calculation slightly easier. - // bits96_127: [ mmmmmmmm | mmmmmmmm ] - // bits64_95: [ | mmmmmmmm mmmmmmmm | ] - // bits32_63: | [ mmmmmmmm | mmmmmmmm ] - // bits0_31: | [ | mmmmmmmm mmmmmmmm ] - // eventually: [ bits128_up | ...bits64_127.... | ..bits0_63... ] - - uint64_t bits0_63 = bits0_31 + (bits32_63 << 32); - uint64_t bits64_127 = bits64_95 + (bits96_127 << 32) + (bits32_63 >> 32) + - (bits0_63 < bits0_31); - uint64_t bits128_up = (bits96_127 >> 32) + (bits64_127 < bits64_95); - if (bits128_up == 0) return {bits64_127, bits0_63}; - - int shift = 64 - base_internal::CountLeadingZeros64(bits128_up); - uint64_t lo = (bits0_63 >> shift) + (bits64_127 << (64 - shift)); - uint64_t hi = (bits64_127 >> shift) + (bits128_up << (64 - shift)); - return {hi, lo}; -} - -// Compute num * 5 ^ expfive, and return the first 128 bits of the result, -// where the first bit is always a one. So PowFive(1, 0) starts 0b100000, -// PowFive(1, 1) starts 0b101000, PowFive(1, 2) starts 0b110010, etc. -static std::pair<uint64_t, uint64_t> PowFive(uint64_t num, int expfive) { - std::pair<uint64_t, uint64_t> result = {num, 0}; - while (expfive >= 13) { - // 5^13 is the highest power of five that will fit in a 32-bit integer. - result = Mul32(result, 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5); - expfive -= 13; - } - constexpr int powers_of_five[13] = { - 1, - 5, - 5 * 5, - 5 * 5 * 5, - 5 * 5 * 5 * 5, - 5 * 5 * 5 * 5 * 5, - 5 * 5 * 5 * 5 * 5 * 5, - 5 * 5 * 5 * 5 * 5 * 5 * 5, - 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5, - 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5, - 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5, - 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5, - 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5}; - result = Mul32(result, powers_of_five[expfive & 15]); - int shift = base_internal::CountLeadingZeros64(result.first); - if (shift != 0) { - result.first = (result.first << shift) + (result.second >> (64 - shift)); - result.second = (result.second << shift); - } - return result; -} - -struct ExpDigits { - int32_t exponent; - char digits[6]; -}; - -// SplitToSix converts value, a positive double-precision floating-point number, -// into a base-10 exponent and 6 ASCII digits, where the first digit is never -// zero. For example, SplitToSix(1) returns an exponent of zero and a digits -// array of {'1', '0', '0', '0', '0', '0'}. If value is exactly halfway between -// two possible representations, e.g. value = 100000.5, then "round to even" is -// performed. -static ExpDigits SplitToSix(const double value) { - ExpDigits exp_dig; - int exp = 5; - double d = value; - // First step: calculate a close approximation of the output, where the - // value d will be between 100,000 and 999,999, representing the digits - // in the output ASCII array, and exp is the base-10 exponent. It would be - // faster to use a table here, and to look up the base-2 exponent of value, - // however value is an IEEE-754 64-bit number, so the table would have 2,000 - // entries, which is not cache-friendly. - if (d >= 999999.5) { - if (d >= 1e+261) exp += 256, d *= 1e-256; - if (d >= 1e+133) exp += 128, d *= 1e-128; - if (d >= 1e+69) exp += 64, d *= 1e-64; - if (d >= 1e+37) exp += 32, d *= 1e-32; - if (d >= 1e+21) exp += 16, d *= 1e-16; - if (d >= 1e+13) exp += 8, d *= 1e-8; - if (d >= 1e+9) exp += 4, d *= 1e-4; - if (d >= 1e+7) exp += 2, d *= 1e-2; - if (d >= 1e+6) exp += 1, d *= 1e-1; - } else { - if (d < 1e-250) exp -= 256, d *= 1e256; - if (d < 1e-122) exp -= 128, d *= 1e128; - if (d < 1e-58) exp -= 64, d *= 1e64; - if (d < 1e-26) exp -= 32, d *= 1e32; - if (d < 1e-10) exp -= 16, d *= 1e16; - if (d < 1e-2) exp -= 8, d *= 1e8; - if (d < 1e+2) exp -= 4, d *= 1e4; - if (d < 1e+4) exp -= 2, d *= 1e2; - if (d < 1e+5) exp -= 1, d *= 1e1; - } - // At this point, d is in the range [99999.5..999999.5) and exp is in the - // range [-324..308]. Since we need to round d up, we want to add a half - // and truncate. - // However, the technique above may have lost some precision, due to its - // repeated multiplication by constants that each may be off by half a bit - // of precision. This only matters if we're close to the edge though. - // Since we'd like to know if the fractional part of d is close to a half, - // we multiply it by 65536 and see if the fractional part is close to 32768. - // (The number doesn't have to be a power of two,but powers of two are faster) - uint64_t d64k = d * 65536; - int dddddd; // A 6-digit decimal integer. - if ((d64k % 65536) == 32767 || (d64k % 65536) == 32768) { - // OK, it's fairly likely that precision was lost above, which is - // not a surprise given only 52 mantissa bits are available. Therefore - // redo the calculation using 128-bit numbers. (64 bits are not enough). - - // Start out with digits rounded down; maybe add one below. - dddddd = static_cast<int>(d64k / 65536); - - // mantissa is a 64-bit integer representing M.mmm... * 2^63. The actual - // value we're representing, of course, is M.mmm... * 2^exp2. - int exp2; - double m = std::frexp(value, &exp2); - uint64_t mantissa = m * (32768.0 * 65536.0 * 65536.0 * 65536.0); - // std::frexp returns an m value in the range [0.5, 1.0), however we - // can't multiply it by 2^64 and convert to an integer because some FPUs - // throw an exception when converting an number higher than 2^63 into an - // integer - even an unsigned 64-bit integer! Fortunately it doesn't matter - // since m only has 52 significant bits anyway. - mantissa <<= 1; - exp2 -= 64; // not needed, but nice for debugging - - // OK, we are here to compare: - // (dddddd + 0.5) * 10^(exp-5) vs. mantissa * 2^exp2 - // so we can round up dddddd if appropriate. Those values span the full - // range of 600 orders of magnitude of IEE 64-bit floating-point. - // Fortunately, we already know they are very close, so we don't need to - // track the base-2 exponent of both sides. This greatly simplifies the - // the math since the 2^exp2 calculation is unnecessary and the power-of-10 - // calculation can become a power-of-5 instead. - - std::pair<uint64_t, uint64_t> edge, val; - if (exp >= 6) { - // Compare (dddddd + 0.5) * 5 ^ (exp - 5) to mantissa - // Since we're tossing powers of two, 2 * dddddd + 1 is the - // same as dddddd + 0.5 - edge = PowFive(2 * dddddd + 1, exp - 5); - - val.first = mantissa; - val.second = 0; - } else { - // We can't compare (dddddd + 0.5) * 5 ^ (exp - 5) to mantissa as we did - // above because (exp - 5) is negative. So we compare (dddddd + 0.5) to - // mantissa * 5 ^ (5 - exp) - edge = PowFive(2 * dddddd + 1, 0); - - val = PowFive(mantissa, 5 - exp); - } - // printf("exp=%d %016lx %016lx vs %016lx %016lx\n", exp, val.first, - // val.second, edge.first, edge.second); - if (val > edge) { - dddddd++; - } else if (val == edge) { - dddddd += (dddddd & 1); - } - } else { - // Here, we are not close to the edge. - dddddd = static_cast<int>((d64k + 32768) / 65536); - } - if (dddddd == 1000000) { - dddddd = 100000; - exp += 1; - } - exp_dig.exponent = exp; - - int two_digits = dddddd / 10000; - dddddd -= two_digits * 10000; - numbers_internal::PutTwoDigits(two_digits, &exp_dig.digits[0]); - - two_digits = dddddd / 100; - dddddd -= two_digits * 100; - numbers_internal::PutTwoDigits(two_digits, &exp_dig.digits[2]); - - numbers_internal::PutTwoDigits(dddddd, &exp_dig.digits[4]); - return exp_dig; -} - -// Helper function for fast formatting of floating-point. -// The result is the same as "%g", a.k.a. "%.6g". -size_t numbers_internal::SixDigitsToBuffer(double d, char* const buffer) { - static_assert(std::numeric_limits<float>::is_iec559, - "IEEE-754/IEC-559 support only"); - - char* out = buffer; // we write data to out, incrementing as we go, but - // FloatToBuffer always returns the address of the buffer - // passed in. - - if (std::isnan(d)) { - strcpy(out, "nan"); // NOLINT(runtime/printf) - return 3; - } - if (d == 0) { // +0 and -0 are handled here - if (std::signbit(d)) *out++ = '-'; - *out++ = '0'; - *out = 0; - return out - buffer; - } - if (d < 0) { - *out++ = '-'; - d = -d; - } - if (std::isinf(d)) { - strcpy(out, "inf"); // NOLINT(runtime/printf) - return out + 3 - buffer; - } - - auto exp_dig = SplitToSix(d); - int exp = exp_dig.exponent; - const char* digits = exp_dig.digits; - out[0] = '0'; - out[1] = '.'; - switch (exp) { - case 5: - memcpy(out, &digits[0], 6), out += 6; - *out = 0; - return out - buffer; - case 4: - memcpy(out, &digits[0], 5), out += 5; - if (digits[5] != '0') { - *out++ = '.'; - *out++ = digits[5]; - } - *out = 0; - return out - buffer; - case 3: - memcpy(out, &digits[0], 4), out += 4; - if ((digits[5] | digits[4]) != '0') { - *out++ = '.'; - *out++ = digits[4]; - if (digits[5] != '0') *out++ = digits[5]; - } - *out = 0; - return out - buffer; - case 2: - memcpy(out, &digits[0], 3), out += 3; - *out++ = '.'; - memcpy(out, &digits[3], 3); - out += 3; - while (out[-1] == '0') --out; - if (out[-1] == '.') --out; - *out = 0; - return out - buffer; - case 1: - memcpy(out, &digits[0], 2), out += 2; - *out++ = '.'; - memcpy(out, &digits[2], 4); - out += 4; - while (out[-1] == '0') --out; - if (out[-1] == '.') --out; - *out = 0; - return out - buffer; - case 0: - memcpy(out, &digits[0], 1), out += 1; - *out++ = '.'; - memcpy(out, &digits[1], 5); - out += 5; - while (out[-1] == '0') --out; - if (out[-1] == '.') --out; - *out = 0; - return out - buffer; - case -4: - out[2] = '0'; - ++out; - ABSL_FALLTHROUGH_INTENDED; - case -3: - out[2] = '0'; - ++out; - ABSL_FALLTHROUGH_INTENDED; - case -2: - out[2] = '0'; - ++out; - ABSL_FALLTHROUGH_INTENDED; - case -1: - out += 2; - memcpy(out, &digits[0], 6); - out += 6; - while (out[-1] == '0') --out; - *out = 0; - return out - buffer; - } - assert(exp < -4 || exp >= 6); - out[0] = digits[0]; - assert(out[1] == '.'); - out += 2; - memcpy(out, &digits[1], 5), out += 5; - while (out[-1] == '0') --out; - if (out[-1] == '.') --out; - *out++ = 'e'; - if (exp > 0) { - *out++ = '+'; - } else { - *out++ = '-'; - exp = -exp; - } - if (exp > 99) { - int dig1 = exp / 100; - exp -= dig1 * 100; - *out++ = '0' + dig1; - } - PutTwoDigits(exp, out); - out += 2; - *out = 0; - return out - buffer; -} - -namespace { -// Represents integer values of digits. -// Uses 36 to indicate an invalid character since we support -// bases up to 36. -static const int8_t kAsciiToInt[256] = { - 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, // 16 36s. - 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, - 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 0, 1, 2, 3, 4, 5, - 6, 7, 8, 9, 36, 36, 36, 36, 36, 36, 36, 10, 11, 12, 13, 14, 15, 16, 17, - 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, - 36, 36, 36, 36, 36, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, - 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 36, 36, 36, 36, 36, 36, - 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, - 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, - 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, - 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, - 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, - 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, - 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36, 36}; - -// Parse the sign and optional hex or oct prefix in text. -inline bool safe_parse_sign_and_base(absl::string_view* text /*inout*/, - int* base_ptr /*inout*/, - bool* negative_ptr /*output*/) { - if (text->data() == nullptr) { - return false; - } - - const char* start = text->data(); - const char* end = start + text->size(); - int base = *base_ptr; - - // Consume whitespace. - while (start < end && absl::ascii_isspace(start[0])) { - ++start; - } - while (start < end && absl::ascii_isspace(end[-1])) { - --end; - } - if (start >= end) { - return false; - } - - // Consume sign. - *negative_ptr = (start[0] == '-'); - if (*negative_ptr || start[0] == '+') { - ++start; - if (start >= end) { - return false; - } - } - - // Consume base-dependent prefix. - // base 0: "0x" -> base 16, "0" -> base 8, default -> base 10 - // base 16: "0x" -> base 16 - // Also validate the base. - if (base == 0) { - if (end - start >= 2 && start[0] == '0' && - (start[1] == 'x' || start[1] == 'X')) { - base = 16; - start += 2; - if (start >= end) { - // "0x" with no digits after is invalid. - return false; - } - } else if (end - start >= 1 && start[0] == '0') { - base = 8; - start += 1; - } else { - base = 10; - } - } else if (base == 16) { - if (end - start >= 2 && start[0] == '0' && - (start[1] == 'x' || start[1] == 'X')) { - start += 2; - if (start >= end) { - // "0x" with no digits after is invalid. - return false; - } - } - } else if (base >= 2 && base <= 36) { - // okay - } else { - return false; - } - *text = absl::string_view(start, end - start); - *base_ptr = base; - return true; -} - -// Consume digits. -// -// The classic loop: -// -// for each digit -// value = value * base + digit -// value *= sign -// -// The classic loop needs overflow checking. It also fails on the most -// negative integer, -2147483648 in 32-bit two's complement representation. -// -// My improved loop: -// -// if (!negative) -// for each digit -// value = value * base -// value = value + digit -// else -// for each digit -// value = value * base -// value = value - digit -// -// Overflow checking becomes simple. - -// Lookup tables per IntType: -// vmax/base and vmin/base are precomputed because division costs at least 8ns. -// TODO(junyer): Doing this per base instead (i.e. an array of structs, not a -// struct of arrays) would probably be better in terms of d-cache for the most -// commonly used bases. -template <typename IntType> -struct LookupTables { - ABSL_CONST_INIT static const IntType kVmaxOverBase[]; - ABSL_CONST_INIT static const IntType kVminOverBase[]; -}; - -// An array initializer macro for X/base where base in [0, 36]. -// However, note that lookups for base in [0, 1] should never happen because -// base has been validated to be in [2, 36] by safe_parse_sign_and_base(). -#define X_OVER_BASE_INITIALIZER(X) \ - { \ - 0, 0, X / 2, X / 3, X / 4, X / 5, X / 6, X / 7, X / 8, X / 9, X / 10, \ - X / 11, X / 12, X / 13, X / 14, X / 15, X / 16, X / 17, X / 18, \ - X / 19, X / 20, X / 21, X / 22, X / 23, X / 24, X / 25, X / 26, \ - X / 27, X / 28, X / 29, X / 30, X / 31, X / 32, X / 33, X / 34, \ - X / 35, X / 36, \ - } - -// uint128& operator/=(uint128) is not constexpr, so hardcode the resulting -// array to avoid a static initializer. -template <> -const uint128 LookupTables<uint128>::kVmaxOverBase[] = { - 0, - 0, - MakeUint128(9223372036854775807u, 18446744073709551615u), - MakeUint128(6148914691236517205u, 6148914691236517205u), - MakeUint128(4611686018427387903u, 18446744073709551615u), - MakeUint128(3689348814741910323u, 3689348814741910323u), - MakeUint128(3074457345618258602u, 12297829382473034410u), - MakeUint128(2635249153387078802u, 5270498306774157604u), - MakeUint128(2305843009213693951u, 18446744073709551615u), - MakeUint128(2049638230412172401u, 14347467612885206812u), - MakeUint128(1844674407370955161u, 11068046444225730969u), - MakeUint128(1676976733973595601u, 8384883669867978007u), - MakeUint128(1537228672809129301u, 6148914691236517205u), - MakeUint128(1418980313362273201u, 4256940940086819603u), - MakeUint128(1317624576693539401u, 2635249153387078802u), - MakeUint128(1229782938247303441u, 1229782938247303441u), - MakeUint128(1152921504606846975u, 18446744073709551615u), - MakeUint128(1085102592571150095u, 1085102592571150095u), - MakeUint128(1024819115206086200u, 16397105843297379214u), - MakeUint128(970881267037344821u, 16504981539634861972u), - MakeUint128(922337203685477580u, 14757395258967641292u), - MakeUint128(878416384462359600u, 14054662151397753612u), - MakeUint128(838488366986797800u, 13415813871788764811u), - MakeUint128(802032351030850070u, 4812194106185100421u), - MakeUint128(768614336404564650u, 12297829382473034410u), - MakeUint128(737869762948382064u, 11805916207174113034u), - MakeUint128(709490156681136600u, 11351842506898185609u), - MakeUint128(683212743470724133u, 17080318586768103348u), - MakeUint128(658812288346769700u, 10540996613548315209u), - MakeUint128(636094623231363848u, 15266270957552732371u), - MakeUint128(614891469123651720u, 9838263505978427528u), - MakeUint128(595056260442243600u, 9520900167075897608u), - MakeUint128(576460752303423487u, 18446744073709551615u), - MakeUint128(558992244657865200u, 8943875914525843207u), - MakeUint128(542551296285575047u, 9765923333140350855u), - MakeUint128(527049830677415760u, 8432797290838652167u), - MakeUint128(512409557603043100u, 8198552921648689607u), -}; - -template <typename IntType> -const IntType LookupTables<IntType>::kVmaxOverBase[] = - X_OVER_BASE_INITIALIZER(std::numeric_limits<IntType>::max()); - -template <typename IntType> -const IntType LookupTables<IntType>::kVminOverBase[] = - X_OVER_BASE_INITIALIZER(std::numeric_limits<IntType>::min()); - -#undef X_OVER_BASE_INITIALIZER - -template <typename IntType> -inline bool safe_parse_positive_int(absl::string_view text, int base, - IntType* value_p) { - IntType value = 0; - const IntType vmax = std::numeric_limits<IntType>::max(); - assert(vmax > 0); - assert(base >= 0); - assert(vmax >= static_cast<IntType>(base)); - const IntType vmax_over_base = LookupTables<IntType>::kVmaxOverBase[base]; - assert(base < 2 || - std::numeric_limits<IntType>::max() / base == vmax_over_base); - const char* start = text.data(); - const char* end = start + text.size(); - // loop over digits - for (; start < end; ++start) { - unsigned char c = static_cast<unsigned char>(start[0]); - int digit = kAsciiToInt[c]; - if (digit >= base) { - *value_p = value; - return false; - } - if (value > vmax_over_base) { - *value_p = vmax; - return false; - } - value *= base; - if (value > vmax - digit) { - *value_p = vmax; - return false; - } - value += digit; - } - *value_p = value; - return true; -} - -template <typename IntType> -inline bool safe_parse_negative_int(absl::string_view text, int base, - IntType* value_p) { - IntType value = 0; - const IntType vmin = std::numeric_limits<IntType>::min(); - assert(vmin < 0); - assert(vmin <= 0 - base); - IntType vmin_over_base = LookupTables<IntType>::kVminOverBase[base]; - assert(base < 2 || - std::numeric_limits<IntType>::min() / base == vmin_over_base); - // 2003 c++ standard [expr.mul] - // "... the sign of the remainder is implementation-defined." - // Although (vmin/base)*base + vmin%base is always vmin. - // 2011 c++ standard tightens the spec but we cannot rely on it. - // TODO(junyer): Handle this in the lookup table generation. - if (vmin % base > 0) { - vmin_over_base += 1; - } - const char* start = text.data(); - const char* end = start + text.size(); - // loop over digits - for (; start < end; ++start) { - unsigned char c = static_cast<unsigned char>(start[0]); - int digit = kAsciiToInt[c]; - if (digit >= base) { - *value_p = value; - return false; - } - if (value < vmin_over_base) { - *value_p = vmin; - return false; - } - value *= base; - if (value < vmin + digit) { - *value_p = vmin; - return false; - } - value -= digit; - } - *value_p = value; - return true; -} - -// Input format based on POSIX.1-2008 strtol -// http://pubs.opengroup.org/onlinepubs/9699919799/functions/strtol.html -template <typename IntType> -inline bool safe_int_internal(absl::string_view text, IntType* value_p, - int base) { - *value_p = 0; - bool negative; - if (!safe_parse_sign_and_base(&text, &base, &negative)) { - return false; - } - if (!negative) { - return safe_parse_positive_int(text, base, value_p); - } else { - return safe_parse_negative_int(text, base, value_p); - } -} - -template <typename IntType> -inline bool safe_uint_internal(absl::string_view text, IntType* value_p, - int base) { - *value_p = 0; - bool negative; - if (!safe_parse_sign_and_base(&text, &base, &negative) || negative) { - return false; - } - return safe_parse_positive_int(text, base, value_p); -} -} // anonymous namespace - -namespace numbers_internal { - -// Digit conversion. -ABSL_CONST_INIT ABSL_DLL const char kHexChar[] = - "0123456789abcdef"; - -ABSL_CONST_INIT ABSL_DLL const char kHexTable[513] = - "000102030405060708090a0b0c0d0e0f" - "101112131415161718191a1b1c1d1e1f" - "202122232425262728292a2b2c2d2e2f" - "303132333435363738393a3b3c3d3e3f" - "404142434445464748494a4b4c4d4e4f" - "505152535455565758595a5b5c5d5e5f" - "606162636465666768696a6b6c6d6e6f" - "707172737475767778797a7b7c7d7e7f" - "808182838485868788898a8b8c8d8e8f" - "909192939495969798999a9b9c9d9e9f" - "a0a1a2a3a4a5a6a7a8a9aaabacadaeaf" - "b0b1b2b3b4b5b6b7b8b9babbbcbdbebf" - "c0c1c2c3c4c5c6c7c8c9cacbcccdcecf" - "d0d1d2d3d4d5d6d7d8d9dadbdcdddedf" - "e0e1e2e3e4e5e6e7e8e9eaebecedeeef" - "f0f1f2f3f4f5f6f7f8f9fafbfcfdfeff"; - -ABSL_CONST_INIT ABSL_DLL const char two_ASCII_digits[100][2] = { - {'0', '0'}, {'0', '1'}, {'0', '2'}, {'0', '3'}, {'0', '4'}, {'0', '5'}, - {'0', '6'}, {'0', '7'}, {'0', '8'}, {'0', '9'}, {'1', '0'}, {'1', '1'}, - {'1', '2'}, {'1', '3'}, {'1', '4'}, {'1', '5'}, {'1', '6'}, {'1', '7'}, - {'1', '8'}, {'1', '9'}, {'2', '0'}, {'2', '1'}, {'2', '2'}, {'2', '3'}, - {'2', '4'}, {'2', '5'}, {'2', '6'}, {'2', '7'}, {'2', '8'}, {'2', '9'}, - {'3', '0'}, {'3', '1'}, {'3', '2'}, {'3', '3'}, {'3', '4'}, {'3', '5'}, - {'3', '6'}, {'3', '7'}, {'3', '8'}, {'3', '9'}, {'4', '0'}, {'4', '1'}, - {'4', '2'}, {'4', '3'}, {'4', '4'}, {'4', '5'}, {'4', '6'}, {'4', '7'}, - {'4', '8'}, {'4', '9'}, {'5', '0'}, {'5', '1'}, {'5', '2'}, {'5', '3'}, - {'5', '4'}, {'5', '5'}, {'5', '6'}, {'5', '7'}, {'5', '8'}, {'5', '9'}, - {'6', '0'}, {'6', '1'}, {'6', '2'}, {'6', '3'}, {'6', '4'}, {'6', '5'}, - {'6', '6'}, {'6', '7'}, {'6', '8'}, {'6', '9'}, {'7', '0'}, {'7', '1'}, - {'7', '2'}, {'7', '3'}, {'7', '4'}, {'7', '5'}, {'7', '6'}, {'7', '7'}, - {'7', '8'}, {'7', '9'}, {'8', '0'}, {'8', '1'}, {'8', '2'}, {'8', '3'}, - {'8', '4'}, {'8', '5'}, {'8', '6'}, {'8', '7'}, {'8', '8'}, {'8', '9'}, - {'9', '0'}, {'9', '1'}, {'9', '2'}, {'9', '3'}, {'9', '4'}, {'9', '5'}, - {'9', '6'}, {'9', '7'}, {'9', '8'}, {'9', '9'}}; - -bool safe_strto32_base(absl::string_view text, int32_t* value, int base) { - return safe_int_internal<int32_t>(text, value, base); -} - -bool safe_strto64_base(absl::string_view text, int64_t* value, int base) { - return safe_int_internal<int64_t>(text, value, base); -} - -bool safe_strtou32_base(absl::string_view text, uint32_t* value, int base) { - return safe_uint_internal<uint32_t>(text, value, base); -} - -bool safe_strtou64_base(absl::string_view text, uint64_t* value, int base) { - return safe_uint_internal<uint64_t>(text, value, base); -} - -bool safe_strtou128_base(absl::string_view text, uint128* value, int base) { - return safe_uint_internal<absl::uint128>(text, value, base); -} - -} // namespace numbers_internal -ABSL_NAMESPACE_END -} // namespace absl |