| // 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. |
| // These conditions are constexpr bools to suppress MSVC warning C4127. |
| constexpr bool kIsSigned = static_cast<int_type>(1) - 2 < 0; |
| constexpr bool kUse64Bit = sizeof(i) > 32 / 8; |
| if (kIsSigned) { |
| if (kUse64Bit) { |
| return FastIntToBuffer(static_cast<int64_t>(i), buffer); |
| } else { |
| return FastIntToBuffer(static_cast<int32_t>(i), buffer); |
| } |
| } else { |
| if (kUse64Bit) { |
| return FastIntToBuffer(static_cast<uint64_t>(i), buffer); |
| } else { |
| 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. |
| // These conditions are constexpr bools to suppress MSVC warning C4127. |
| constexpr bool kIsSigned = static_cast<int_type>(1) - 2 < 0; |
| constexpr bool kUse64Bit = sizeof(*out) == 64 / 8; |
| if (kIsSigned) { |
| if (kUse64Bit) { |
| int64_t val; |
| parsed = numbers_internal::safe_strto64_base(s, &val, base); |
| *out = static_cast<int_type>(val); |
| } else { |
| int32_t val; |
| parsed = numbers_internal::safe_strto32_base(s, &val, base); |
| *out = static_cast<int_type>(val); |
| } |
| } else { |
| if (kUse64Bit) { |
| uint64_t val; |
| parsed = numbers_internal::safe_strtou64_base(s, &val, base); |
| *out = static_cast<int_type>(val); |
| } else { |
| 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_ |