absl/types/bad_optional_access.h

0001 // Copyright 2018 The Abseil Authors.
0002 //
0003 // Licensed under the Apache License, Version 2.0 (the "License");
0004 // you may not use this file except in compliance with the License.
0005 // You may obtain a copy of the License at
0006 //
0007 //      https://www.apache.org/licenses/LICENSE-2.0
0008 //
0009 // Unless required by applicable law or agreed to in writing, software
0010 // distributed under the License is distributed on an "AS IS" BASIS,
0011 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
0012 // See the License for the specific language governing permissions and
0013 // limitations under the License.
0014 //
0015 // -----------------------------------------------------------------------------
0016 // bad_optional_access.h
0017 // -----------------------------------------------------------------------------
0018 //
0019 // This header file defines the `absl::bad_optional_access` type.
0020
0021 #ifndef ABSL_TYPES_BAD_OPTIONAL_ACCESS_H_
0022 #define ABSL_TYPES_BAD_OPTIONAL_ACCESS_H_
0023
0024 #include <stdexcept>
0025
0026 #include "absl/base/config.h"
0027
0028 #ifdef ABSL_USES_STD_OPTIONAL
0029
0030 #include <optional>
0031
0032 namespace absl {
0033 ABSL_NAMESPACE_BEGIN
0034 using std::bad_optional_access;
0035 ABSL_NAMESPACE_END
0036 }  // namespace absl
0037
0038 #else  // ABSL_USES_STD_OPTIONAL
0039
0040 namespace absl {
0041 ABSL_NAMESPACE_BEGIN
0042
0043 // -----------------------------------------------------------------------------
0044 // bad_optional_access
0045 // -----------------------------------------------------------------------------
0046 //
0047 // An `absl::bad_optional_access` type is an exception type that is thrown when
0048 // attempting to access an `absl::optional` object that does not contain a
0049 // value.
0050 //
0051 // Example:
0052 //
0053 //   absl::optional<int> o;
0054 //
0055 //   try {
0056 //     int n = o.value();
0057 //   } catch(const absl::bad_optional_access& e) {
0058 //     std::cout << "Bad optional access: " << e.what() << '\n';
0059 //   }
0060 class bad_optional_access : public std::exception {
0061  public:
0062   bad_optional_access() = default;
0063   ~bad_optional_access() override;
0064   const char* what() const noexcept override;
0065 };
0066
0067 namespace optional_internal {
0068
0069 // throw delegator
0070 [[noreturn]] ABSL_DLL void throw_bad_optional_access();
0071
0072 }  // namespace optional_internal
0073 ABSL_NAMESPACE_END
0074 }  // namespace absl
0075
0076 #endif  // ABSL_USES_STD_OPTIONAL
0077
0078 #endif  // ABSL_TYPES_BAD_OPTIONAL_ACCESS_H_