72 lines
1.9 KiB
C++
72 lines
1.9 KiB
C++
/*
|
|
* Copyright (C) 2019 The Android Open Source Project
|
|
*
|
|
* 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.
|
|
*/
|
|
|
|
#pragma once
|
|
|
|
#include <string>
|
|
#include <variant>
|
|
|
|
#include <android-base/logging.h>
|
|
|
|
namespace android {
|
|
namespace jsonpb {
|
|
|
|
template <typename T>
|
|
struct ErrorOr {
|
|
template <class... Args>
|
|
explicit ErrorOr(Args&&... args) : data_(kIndex1, std::forward<Args>(args)...) {}
|
|
T& operator*() {
|
|
CHECK(ok());
|
|
return *std::get_if<1u>(&data_);
|
|
}
|
|
const T& operator*() const {
|
|
CHECK(ok());
|
|
return *std::get_if<1u>(&data_);
|
|
}
|
|
T* operator->() {
|
|
CHECK(ok());
|
|
return std::get_if<1u>(&data_);
|
|
}
|
|
const T* operator->() const {
|
|
CHECK(ok());
|
|
return std::get_if<1u>(&data_);
|
|
}
|
|
const std::string& error() const {
|
|
CHECK(!ok());
|
|
return *std::get_if<0u>(&data_);
|
|
}
|
|
bool ok() const { return data_.index() != 0; }
|
|
static ErrorOr<T> MakeError(const std::string& message) {
|
|
return ErrorOr<T>(message, Tag::kDummy);
|
|
}
|
|
|
|
private:
|
|
enum class Tag { kDummy };
|
|
static constexpr std::in_place_index_t<0> kIndex0{};
|
|
static constexpr std::in_place_index_t<1> kIndex1{};
|
|
ErrorOr(const std::string& msg, Tag) : data_(kIndex0, msg) {}
|
|
|
|
std::variant<std::string, T> data_;
|
|
};
|
|
|
|
template <typename T>
|
|
inline ErrorOr<T> MakeError(const std::string& message) {
|
|
return ErrorOr<T>::MakeError(message);
|
|
}
|
|
|
|
} // namespace jsonpb
|
|
} // namespace android
|