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Diffstat (limited to 'third_party/abseil_cpp/absl/strings/charconv.h')
| -rw-r--r-- | third_party/abseil_cpp/absl/strings/charconv.h | 119 |
1 files changed, 119 insertions, 0 deletions
diff --git a/third_party/abseil_cpp/absl/strings/charconv.h b/third_party/abseil_cpp/absl/strings/charconv.h new file mode 100644 index 0000000000..e04be32f95 --- /dev/null +++ b/third_party/abseil_cpp/absl/strings/charconv.h @@ -0,0 +1,119 @@ +// 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) + +#include "absl/base/config.h" + +namespace absl { +ABSL_NAMESPACE_BEGIN + +// 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 3080 and DR 3081. 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 3081, 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; +} + +ABSL_NAMESPACE_END +} // namespace absl + +#endif // ABSL_STRINGS_CHARCONV_H_ |