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- // 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_
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