146 lines
3.7 KiB
C++
146 lines
3.7 KiB
C++
/*
|
|
* Copyright (C) 2018 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.
|
|
*/
|
|
|
|
#ifndef IDMAP2_INCLUDE_IDMAP2_RESULT_H_
|
|
#define IDMAP2_INCLUDE_IDMAP2_RESULT_H_
|
|
|
|
#include <string>
|
|
#include <utility>
|
|
#include <variant>
|
|
|
|
#include "android-base/logging.h" // CHECK
|
|
|
|
namespace android::idmap2 {
|
|
|
|
using Unit = std::monostate;
|
|
|
|
class Error {
|
|
public:
|
|
explicit Error(const Error& parent) = default;
|
|
|
|
// NOLINTNEXTLINE(cert-dcl50-cpp)
|
|
explicit Error(const char* fmt, ...) __attribute__((__format__(printf, 2, 3)));
|
|
|
|
// NOLINTNEXTLINE(cert-dcl50-cpp)
|
|
explicit Error(const Error& parent, const char* fmt, ...)
|
|
__attribute__((__format__(printf, 3, 4)));
|
|
|
|
inline std::string GetMessage() const {
|
|
return msg_;
|
|
}
|
|
|
|
private:
|
|
std::string msg_;
|
|
};
|
|
|
|
template <typename T>
|
|
class Result {
|
|
public:
|
|
Result(const T& value); // NOLINT(runtime/explicit)
|
|
Result(T&& value) noexcept; // NOLINT(runtime/explicit)
|
|
|
|
Result(const Error& error); // NOLINT(runtime/explicit)
|
|
Result(Error&& error) noexcept; // NOLINT(runtime/explicit)
|
|
|
|
Result(const Result& error) = default;
|
|
|
|
Result& operator=(const Result& rhs) = default;
|
|
Result& operator=(Result&& rhs) noexcept = default;
|
|
|
|
explicit operator bool() const;
|
|
|
|
constexpr const T& operator*() const&;
|
|
T& operator*() &;
|
|
|
|
constexpr const T* operator->() const&;
|
|
T* operator->() &;
|
|
|
|
std::string GetErrorMessage() const;
|
|
Error GetError() const;
|
|
|
|
private:
|
|
bool is_ok() const;
|
|
|
|
std::variant<T, Error> data_;
|
|
};
|
|
|
|
template <typename T>
|
|
Result<T>::Result(const T& value) : data_(std::in_place_type<T>, value) {
|
|
}
|
|
|
|
template <typename T>
|
|
Result<T>::Result(T&& value) noexcept : data_(std::in_place_type<T>, std::forward<T>(value)) {
|
|
}
|
|
|
|
template <typename T>
|
|
Result<T>::Result(const Error& error) : data_(std::in_place_type<Error>, error) {
|
|
}
|
|
|
|
template <typename T>
|
|
Result<T>::Result(Error&& error) noexcept
|
|
: data_(std::in_place_type<Error>, std::forward<Error>(error)) {
|
|
}
|
|
|
|
template <typename T>
|
|
Result<T>::operator bool() const {
|
|
return is_ok();
|
|
}
|
|
|
|
template <typename T>
|
|
constexpr const T& Result<T>::operator*() const& {
|
|
CHECK(is_ok()) << "Result<T>::operator* called in ERROR state";
|
|
return std::get<T>(data_);
|
|
}
|
|
|
|
template <typename T>
|
|
T& Result<T>::operator*() & {
|
|
CHECK(is_ok()) << "Result<T>::operator* called in ERROR state";
|
|
return std::get<T>(data_);
|
|
}
|
|
|
|
template <typename T>
|
|
constexpr const T* Result<T>::operator->() const& {
|
|
CHECK(is_ok()) << "Result<T>::operator-> called in ERROR state";
|
|
return &std::get<T>(data_);
|
|
}
|
|
|
|
template <typename T>
|
|
T* Result<T>::operator->() & {
|
|
CHECK(is_ok()) << "Result<T>::operator-> called in ERROR state";
|
|
return &std::get<T>(data_);
|
|
}
|
|
|
|
template <typename T>
|
|
inline std::string Result<T>::GetErrorMessage() const {
|
|
CHECK(!is_ok()) << "Result<T>::GetErrorMessage called in OK state";
|
|
return std::get<Error>(data_).GetMessage();
|
|
}
|
|
|
|
template <typename T>
|
|
inline Error Result<T>::GetError() const {
|
|
CHECK(!is_ok()) << "Result<T>::GetError called in OK state";
|
|
return Error(std::get<Error>(data_));
|
|
}
|
|
|
|
template <typename T>
|
|
inline bool Result<T>::is_ok() const {
|
|
return std::holds_alternative<T>(data_);
|
|
}
|
|
|
|
} // namespace android::idmap2
|
|
|
|
#endif // IDMAP2_INCLUDE_IDMAP2_RESULT_H_
|