| // Copyright 2018 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. |
| |
| #ifndef ABSL_STRINGS_CHARCONV_H_ |
| #define ABSL_STRINGS_CHARCONV_H_ |
| |
| #include <system_error> // NOLINT(build/c++11) |
| |
| namespace absl { |
| |
| // Workalike compatibilty version of std::chars_format from C++17. |
| // |
| // This is an bitfield enumerator which can be passed to absl::from_chars to |
| // configure the string-to-float conversion. |
| enum class chars_format { |
| scientific = 1, |
| fixed = 2, |
| hex = 4, |
| general = fixed | scientific, |
| }; |
| |
| // The return result of a string-to-number conversion. |
| // |
| // `ec` will be set to `invalid_argument` if a well-formed number was not found |
| // at the start of the input range, `result_out_of_range` if a well-formed |
| // number was found, but it was out of the representable range of the requested |
| // type, or to std::errc() otherwise. |
| // |
| // If a well-formed number was found, `ptr` is set to one past the sequence of |
| // characters that were successfully parsed. If none was found, `ptr` is set |
| // to the `first` argument to from_chars. |
| struct from_chars_result { |
| const char* ptr; |
| std::errc ec; |
| }; |
| |
| // Workalike compatibilty version of std::from_chars from C++17. Currently |
| // this only supports the `double` and `float` types. |
| // |
| // This interface incorporates the proposed resolutions for library issues |
| // DR 3800 and DR 3801. If these are adopted with different wording, |
| // Abseil's behavior will change to match the standard. (The behavior most |
| // likely to change is for DR 3801, which says what `value` will be set to in |
| // the case of overflow and underflow. Code that wants to avoid possible |
| // breaking changes in this area should not depend on `value` when the returned |
| // from_chars_result indicates a range error.) |
| // |
| // Searches the range [first, last) for the longest matching pattern beginning |
| // at `first` that represents a floating point number. If one is found, store |
| // the result in `value`. |
| // |
| // The matching pattern format is almost the same as that of strtod(), except |
| // that C locale is not respected, and an initial '+' character in the input |
| // range will never be matched. |
| // |
| // If `fmt` is set, it must be one of the enumerator values of the chars_format. |
| // (This is despite the fact that chars_format is a bitmask type.) If set to |
| // `scientific`, a matching number must contain an exponent. If set to `fixed`, |
| // then an exponent will never match. (For example, the string "1e5" will be |
| // parsed as "1".) If set to `hex`, then a hexadecimal float is parsed in the |
| // format that strtod() accepts, except that a "0x" prefix is NOT matched. |
| // (In particular, in `hex` mode, the input "0xff" results in the largest |
| // matching pattern "0".) |
| absl::from_chars_result from_chars(const char* first, const char* last, |
| double& value, // NOLINT |
| chars_format fmt = chars_format::general); |
| |
| absl::from_chars_result from_chars(const char* first, const char* last, |
| float& value, // NOLINT |
| chars_format fmt = chars_format::general); |
| |
| // std::chars_format is specified as a bitmask type, which means the following |
| // operations must be provided: |
| inline constexpr chars_format operator&(chars_format lhs, chars_format rhs) { |
| return static_cast<chars_format>(static_cast<int>(lhs) & |
| static_cast<int>(rhs)); |
| } |
| inline constexpr chars_format operator|(chars_format lhs, chars_format rhs) { |
| return static_cast<chars_format>(static_cast<int>(lhs) | |
| static_cast<int>(rhs)); |
| } |
| inline constexpr chars_format operator^(chars_format lhs, chars_format rhs) { |
| return static_cast<chars_format>(static_cast<int>(lhs) ^ |
| static_cast<int>(rhs)); |
| } |
| inline constexpr chars_format operator~(chars_format arg) { |
| return static_cast<chars_format>(~static_cast<int>(arg)); |
| } |
| inline chars_format& operator&=(chars_format& lhs, chars_format rhs) { |
| lhs = lhs & rhs; |
| return lhs; |
| } |
| inline chars_format& operator|=(chars_format& lhs, chars_format rhs) { |
| lhs = lhs | rhs; |
| return lhs; |
| } |
| inline chars_format& operator^=(chars_format& lhs, chars_format rhs) { |
| lhs = lhs ^ rhs; |
| return lhs; |
| } |
| |
| } // namespace absl |
| |
| #endif // ABSL_STRINGS_CHARCONV_H_ |