From bd40a41cc142b36c73b881099d08a9d83f7f4780 Mon Sep 17 00:00:00 2001 From: Abseil Team Date: Mon, 18 Jun 2018 13:18:53 -0700 Subject: -- f28d30df5769bb832dec3ff36d2fcd2bcdf494a3 by Shaindel Schwartz : Internal change PiperOrigin-RevId: 201046831 -- 711715a78b7e53dfaafd4d7f08a74e76db22af88 by Mark Barolak : Internal fix PiperOrigin-RevId: 201043684 -- 64b53edd6bf1fa48f74e7f5d33f00f80d5089147 by Shaindel Schwartz : Remove extra whitespace PiperOrigin-RevId: 201041989 -- 0bdd2a0b33657b688e4a04aeba9ebba47e4dc6ca by Shaindel Schwartz : Whitespace fix. PiperOrigin-RevId: 201034413 -- 3deb0ac296ef1b74c4789e114a8a8bf53253f26b by Shaindel Schwartz : Scrub build tags. No functional changes. PiperOrigin-RevId: 201032927 -- da75d0f8b73baa7e8f4e9a092bba546012ed3b71 by Alex Strelnikov : Internal change. PiperOrigin-RevId: 201026131 -- 6815d80caa19870d0c441b6b9816c68db41393a5 by Tom Manshreck : Add documentation for our LTS snapshot branches PiperOrigin-RevId: 201025191 -- 64c3b02006f39e6a8127bbabf9ec947fb45b6504 by Greg Falcon : Provide absl::from_chars for double and float types. This is a forward-compatible implementation of std::from_chars from C++17. This provides exact "round_to_nearest" conversions, and has some nice properties: * Works with string_view (it can convert numbers from non-NUL-terminated buffers) * Never allocates memory * Faster than the standard library strtod() in our toolchain * Uses integer math in its calculations, so is unaffected by floating point environment * Unaffected by C locale Also change SimpleAtod/SimpleAtoi to use this new API under the hood. PiperOrigin-RevId: 201003324 -- 542869258eb100779497c899103dc96aced52749 by Greg Falcon : Internal change PiperOrigin-RevId: 200999200 -- 3aba192775c7f80e2cd7f221b0a73537823c54ea by Gennadiy Rozental : Internal change PiperOrigin-RevId: 200947470 -- daf9b9feedd748d5364a4c06165b7cb7604d3e1e by Mark Barolak : Add an absl:: qualification to a usage of base_internal::SchedulingMode outside of an absl:: namespace. PiperOrigin-RevId: 200748234 -- a8d265290a22d629f3d9bf9f872c204200bfe8c8 by Mark Barolak : Add a missing namespace closing comment to optional.h. PiperOrigin-RevId: 200739934 -- f05af8ee1c6b864dad2df7c907d424209a3e3202 by Abseil Team : Internal change PiperOrigin-RevId: 200719115 GitOrigin-RevId: f28d30df5769bb832dec3ff36d2fcd2bcdf494a3 Change-Id: Ie4fa601078fd4aa57286372611f1d114fdec82c0 --- absl/strings/charconv.h | 115 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 115 insertions(+) create mode 100644 absl/strings/charconv.h (limited to 'absl/strings/charconv.h') diff --git a/absl/strings/charconv.h b/absl/strings/charconv.h new file mode 100644 index 00000000..3e313679 --- /dev/null +++ b/absl/strings/charconv.h @@ -0,0 +1,115 @@ +// 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 +// +// http://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 // 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 std::string-to-float conversion. +enum class chars_format { + scientific = 1, + fixed = 2, + hex = 4, + general = fixed | scientific, +}; + +// The return result of a std::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 std::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(static_cast(lhs) & + static_cast(rhs)); +} +inline constexpr chars_format operator|(chars_format lhs, chars_format rhs) { + return static_cast(static_cast(lhs) | + static_cast(rhs)); +} +inline constexpr chars_format operator^(chars_format lhs, chars_format rhs) { + return static_cast(static_cast(lhs) ^ + static_cast(rhs)); +} +inline constexpr chars_format operator~(chars_format arg) { + return static_cast(~static_cast(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_ -- cgit v1.2.3