| /* |
| * Copyright 2017 The WebRTC Project Authors. All rights reserved. |
| * |
| * Use of this source code is governed by a BSD-style license |
| * that can be found in the LICENSE file in the root of the source |
| * tree. An additional intellectual property rights grant can be found |
| * in the file PATENTS. All contributing project authors may |
| * be found in the AUTHORS file in the root of the source tree. |
| */ |
| |
| #ifndef RTC_BASE_STRING_TO_NUMBER_H_ |
| #define RTC_BASE_STRING_TO_NUMBER_H_ |
| |
| #include <limits> |
| #include <optional> |
| #include <string> |
| #include <type_traits> |
| |
| #include "absl/strings/string_view.h" |
| |
| namespace rtc { |
| |
| // This file declares a family of functions to parse integers from strings. |
| // The standard C library functions either fail to indicate errors (atoi, etc.) |
| // or are a hassle to work with (strtol, sscanf, etc.). The standard C++ library |
| // functions (std::stoi, etc.) indicate errors by throwing exceptions, which |
| // are disabled in WebRTC. |
| // |
| // Integers are parsed using: |
| // std::optional<int-type> StringToNumber(absl::string_view str, |
| // int base = 10); |
| // |
| // These functions parse a value from the beginning of a string into one of the |
| // fundamental integer types, or returns an empty Optional if parsing |
| // failed. Values outside of the range supported by the type will be |
| // rejected. The strings must begin with a digit or a minus sign. No leading |
| // space nor trailing contents are allowed. |
| // By setting base to 0, one of octal, decimal or hexadecimal will be |
| // detected from the string's prefix (0, nothing or 0x, respectively). |
| // If non-zero, base can be set to a value between 2 and 36 inclusively. |
| |
| namespace string_to_number_internal { |
| // These must be (unsigned) long long, to match the signature of strto(u)ll. |
| using unsigned_type = unsigned long long; // NOLINT(runtime/int) |
| using signed_type = long long; // NOLINT(runtime/int) |
| |
| std::optional<signed_type> ParseSigned(absl::string_view str, int base); |
| std::optional<unsigned_type> ParseUnsigned(absl::string_view str, int base); |
| |
| template <typename T> |
| std::optional<T> ParseFloatingPoint(absl::string_view str); |
| } // namespace string_to_number_internal |
| |
| template <typename T> |
| typename std::enable_if<std::is_integral<T>::value && std::is_signed<T>::value, |
| std::optional<T>>::type |
| StringToNumber(absl::string_view str, int base = 10) { |
| using string_to_number_internal::signed_type; |
| static_assert( |
| std::numeric_limits<T>::max() <= |
| std::numeric_limits<signed_type>::max() && |
| std::numeric_limits<T>::lowest() >= |
| std::numeric_limits<signed_type>::lowest(), |
| "StringToNumber only supports signed integers as large as long long int"); |
| std::optional<signed_type> value = |
| string_to_number_internal::ParseSigned(str, base); |
| if (value && *value >= std::numeric_limits<T>::lowest() && |
| *value <= std::numeric_limits<T>::max()) { |
| return static_cast<T>(*value); |
| } |
| return std::nullopt; |
| } |
| |
| template <typename T> |
| typename std::enable_if<std::is_integral<T>::value && |
| std::is_unsigned<T>::value, |
| std::optional<T>>::type |
| StringToNumber(absl::string_view str, int base = 10) { |
| using string_to_number_internal::unsigned_type; |
| static_assert(std::numeric_limits<T>::max() <= |
| std::numeric_limits<unsigned_type>::max(), |
| "StringToNumber only supports unsigned integers as large as " |
| "unsigned long long int"); |
| std::optional<unsigned_type> value = |
| string_to_number_internal::ParseUnsigned(str, base); |
| if (value && *value <= std::numeric_limits<T>::max()) { |
| return static_cast<T>(*value); |
| } |
| return std::nullopt; |
| } |
| |
| template <typename T> |
| typename std::enable_if<std::is_floating_point<T>::value, |
| std::optional<T>>::type |
| StringToNumber(absl::string_view str, int base = 10) { |
| static_assert( |
| std::numeric_limits<T>::max() <= std::numeric_limits<long double>::max(), |
| "StringToNumber only supports floating-point numbers as large " |
| "as long double"); |
| return string_to_number_internal::ParseFloatingPoint<T>(str); |
| } |
| |
| } // namespace rtc |
| |
| #endif // RTC_BASE_STRING_TO_NUMBER_H_ |