// 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. // // ----------------------------------------------------------------------------- // File: numbers.h // ----------------------------------------------------------------------------- // // This package contains functions for converting strings to numbers. For // converting numbers to strings, use `StrCat()` or `StrAppend()` in str_cat.h, // which automatically detect and convert most number values appropriately. #ifndef ABSL_STRINGS_NUMBERS_H_ #define ABSL_STRINGS_NUMBERS_H_ #ifdef __SSE4_2__ #include <x86intrin.h> #endif #include <cstddef> #include <cstdlib> #include <cstring> #include <ctime> #include <limits> #include <string> #include <type_traits> #include "absl/base/config.h" #ifdef __SSE4_2__ // TODO(jorg): Remove this when we figure out the right way // to swap bytes on SSE 4.2 that works with the compilers // we claim to support. Also, add tests for the compiler // that doesn't support the Intel _bswap64 intrinsic but // does support all the SSE 4.2 intrinsics #include "absl/base/internal/endian.h" #endif #include "absl/base/macros.h" #include "absl/base/port.h" #include "absl/numeric/bits.h" #include "absl/numeric/int128.h" #include "absl/strings/string_view.h" namespace absl { ABSL_NAMESPACE_BEGIN // SimpleAtoi() // // Converts the given string (optionally followed or preceded by ASCII // whitespace) into an integer value, returning `true` if successful. The string // must reflect a base-10 integer whose value falls within the range of the // integer type (optionally preceded by a `+` or `-`). If any errors are // encountered, this function returns `false`, leaving `out` in an unspecified // state. template <typename int_type> ABSL_MUST_USE_RESULT bool SimpleAtoi(absl::string_view str, int_type* out); // SimpleAtof() // // Converts the given string (optionally followed or preceded by ASCII // whitespace) into a float, which may be rounded on overflow or underflow, // returning `true` if successful. // See https://en.cppreference.com/w/c/string/byte/strtof for details about the // allowed formats for `str`, except SimpleAtof() is locale-independent and will // always use the "C" locale. If any errors are encountered, this function // returns `false`, leaving `out` in an unspecified state. ABSL_MUST_USE_RESULT bool SimpleAtof(absl::string_view str, float* out); // SimpleAtod() // // Converts the given string (optionally followed or preceded by ASCII // whitespace) into a double, which may be rounded on overflow or underflow, // returning `true` if successful. // See https://en.cppreference.com/w/c/string/byte/strtof for details about the // allowed formats for `str`, except SimpleAtod is locale-independent and will // always use the "C" locale. If any errors are encountered, this function // returns `false`, leaving `out` in an unspecified state. ABSL_MUST_USE_RESULT bool SimpleAtod(absl::string_view str, double* out); // SimpleAtob() // // Converts the given string into a boolean, returning `true` if successful. // The following case-insensitive strings are interpreted as boolean `true`: // "true", "t", "yes", "y", "1". The following case-insensitive strings // are interpreted as boolean `false`: "false", "f", "no", "n", "0". If any // errors are encountered, this function returns `false`, leaving `out` in an // unspecified state. ABSL_MUST_USE_RESULT bool SimpleAtob(absl::string_view str, bool* out); // SimpleHexAtoi() // // Converts a hexadecimal string (optionally followed or preceded by ASCII // whitespace) to an integer, returning `true` if successful. Only valid base-16 // hexadecimal integers whose value falls within the range of the integer type // (optionally preceded by a `+` or `-`) can be converted. A valid hexadecimal // value may include both upper and lowercase character symbols, and may // optionally include a leading "0x" (or "0X") number prefix, which is ignored // by this function. If any errors are encountered, this function returns // `false`, leaving `out` in an unspecified state. template <typename int_type> ABSL_MUST_USE_RESULT bool SimpleHexAtoi(absl::string_view str, int_type* out); // Overloads of SimpleHexAtoi() for 128 bit integers. ABSL_MUST_USE_RESULT inline bool SimpleHexAtoi(absl::string_view str, absl::int128* out); ABSL_MUST_USE_RESULT inline bool SimpleHexAtoi(absl::string_view str, absl::uint128* out); ABSL_NAMESPACE_END } // namespace absl // End of public API. Implementation details follow. namespace absl { ABSL_NAMESPACE_BEGIN namespace numbers_internal { // Digit conversion. ABSL_DLL extern const char kHexChar[17]; // 0123456789abcdef ABSL_DLL extern const char kHexTable[513]; // 000102030405060708090a0b0c0d0e0f1011... ABSL_DLL extern const char two_ASCII_digits[100][2]; // 00, 01, 02, 03... // Writes a two-character representation of 'i' to 'buf'. 'i' must be in the // range 0 <= i < 100, and buf must have space for two characters. Example: // char buf[2]; // PutTwoDigits(42, buf); // // buf[0] == '4' // // buf[1] == '2' inline void PutTwoDigits(size_t i, char* buf) { assert(i < 100); memcpy(buf, two_ASCII_digits[i], 2); } // safe_strto?() functions for implementing SimpleAtoi() bool safe_strto32_base(absl::string_view text, int32_t* value, int base); bool safe_strto64_base(absl::string_view text, int64_t* value, int base); bool safe_strto128_base(absl::string_view text, absl::int128* value, int base); bool safe_strtou32_base(absl::string_view text, uint32_t* value, int base); bool safe_strtou64_base(absl::string_view text, uint64_t* value, int base); bool safe_strtou128_base(absl::string_view text, absl::uint128* value, int base); static const int kFastToBufferSize = 32; static const int kSixDigitsToBufferSize = 16; // Helper function for fast formatting of floating-point values. // The result is the same as printf's "%g", a.k.a. "%.6g"; that is, six // significant digits are returned, trailing zeros are removed, and numbers // outside the range 0.0001-999999 are output using scientific notation // (1.23456e+06). This routine is heavily optimized. // Required buffer size is `kSixDigitsToBufferSize`. size_t SixDigitsToBuffer(double d, char* buffer); // These functions are intended for speed. All functions take an output buffer // as an argument and return a pointer to the last byte they wrote, which is the // terminating '\0'. At most `kFastToBufferSize` bytes are written. char* FastIntToBuffer(int32_t, char*); char* FastIntToBuffer(uint32_t, char*); char* FastIntToBuffer(int64_t, char*); char* FastIntToBuffer(uint64_t, char*); // For enums and integer types that are not an exact match for the types above, // use templates to call the appropriate one of the four overloads above. template <typename int_type> char* FastIntToBuffer(int_type i, char* buffer) { static_assert(sizeof(i) <= 64 / 8, "FastIntToBuffer works only with 64-bit-or-less integers."); // TODO(jorg): This signed-ness check is used because it works correctly // with enums, and it also serves to check that int_type is not a pointer. // If one day something like std::is_signed<enum E> works, switch to it. if (static_cast<int_type>(1) - 2 < 0) { // Signed if (sizeof(i) > 32 / 8) { // 33-bit to 64-bit return FastIntToBuffer(static_cast<int64_t>(i), buffer); } else { // 32-bit or less return FastIntToBuffer(static_cast<int32_t>(i), buffer); } } else { // Unsigned if (sizeof(i) > 32 / 8) { // 33-bit to 64-bit return FastIntToBuffer(static_cast<uint64_t>(i), buffer); } else { // 32-bit or less return FastIntToBuffer(static_cast<uint32_t>(i), buffer); } } } // Implementation of SimpleAtoi, generalized to support arbitrary base (used // with base different from 10 elsewhere in Abseil implementation). template <typename int_type> ABSL_MUST_USE_RESULT bool safe_strtoi_base(absl::string_view s, int_type* out, int base) { static_assert(sizeof(*out) == 4 || sizeof(*out) == 8, "SimpleAtoi works only with 32-bit or 64-bit integers."); static_assert(!std::is_floating_point<int_type>::value, "Use SimpleAtof or SimpleAtod instead."); bool parsed; // TODO(jorg): This signed-ness check is used because it works correctly // with enums, and it also serves to check that int_type is not a pointer. // If one day something like std::is_signed<enum E> works, switch to it. if (static_cast<int_type>(1) - 2 < 0) { // Signed if (sizeof(*out) == 64 / 8) { // 64-bit int64_t val; parsed = numbers_internal::safe_strto64_base(s, &val, base); *out = static_cast<int_type>(val); } else { // 32-bit int32_t val; parsed = numbers_internal::safe_strto32_base(s, &val, base); *out = static_cast<int_type>(val); } } else { // Unsigned if (sizeof(*out) == 64 / 8) { // 64-bit uint64_t val; parsed = numbers_internal::safe_strtou64_base(s, &val, base); *out = static_cast<int_type>(val); } else { // 32-bit uint32_t val; parsed = numbers_internal::safe_strtou32_base(s, &val, base); *out = static_cast<int_type>(val); } } return parsed; } // FastHexToBufferZeroPad16() // // Outputs `val` into `out` as if by `snprintf(out, 17, "%016x", val)` but // without the terminating null character. Thus `out` must be of length >= 16. // Returns the number of non-pad digits of the output (it can never be zero // since 0 has one digit). inline size_t FastHexToBufferZeroPad16(uint64_t val, char* out) { #ifdef __SSE4_2__ uint64_t be = absl::big_endian::FromHost64(val); const auto kNibbleMask = _mm_set1_epi8(0xf); const auto kHexDigits = _mm_setr_epi8('0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'); auto v = _mm_loadl_epi64(reinterpret_cast<__m128i*>(&be)); // load lo dword auto v4 = _mm_srli_epi64(v, 4); // shift 4 right auto il = _mm_unpacklo_epi8(v4, v); // interleave bytes auto m = _mm_and_si128(il, kNibbleMask); // mask out nibbles auto hexchars = _mm_shuffle_epi8(kHexDigits, m); // hex chars _mm_storeu_si128(reinterpret_cast<__m128i*>(out), hexchars); #else for (int i = 0; i < 8; ++i) { auto byte = (val >> (56 - 8 * i)) & 0xFF; auto* hex = &absl::numbers_internal::kHexTable[byte * 2]; std::memcpy(out + 2 * i, hex, 2); } #endif // | 0x1 so that even 0 has 1 digit. return 16 - countl_zero(val | 0x1) / 4; } } // namespace numbers_internal template <typename int_type> ABSL_MUST_USE_RESULT bool SimpleAtoi(absl::string_view str, int_type* out) { return numbers_internal::safe_strtoi_base(str, out, 10); } ABSL_MUST_USE_RESULT inline bool SimpleAtoi(absl::string_view str, absl::int128* out) { return numbers_internal::safe_strto128_base(str, out, 10); } ABSL_MUST_USE_RESULT inline bool SimpleAtoi(absl::string_view str, absl::uint128* out) { return numbers_internal::safe_strtou128_base(str, out, 10); } template <typename int_type> ABSL_MUST_USE_RESULT bool SimpleHexAtoi(absl::string_view str, int_type* out) { return numbers_internal::safe_strtoi_base(str, out, 16); } ABSL_MUST_USE_RESULT inline bool SimpleHexAtoi(absl::string_view str, absl::int128* out) { return numbers_internal::safe_strto128_base(str, out, 16); } ABSL_MUST_USE_RESULT inline bool SimpleHexAtoi(absl::string_view str, absl::uint128* out) { return numbers_internal::safe_strtou128_base(str, out, 16); } ABSL_NAMESPACE_END } // namespace absl #endif // ABSL_STRINGS_NUMBERS_H_