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/*
* libfud
* Copyright 2024 Dominick Allen
*
* 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 FUD_RESULT_HPP
#define FUD_RESULT_HPP
#include <variant>
#include <utility>
namespace fud {
/** \brief A result type which contains either a T on success or an E on error. */
template <typename T, typename E>
class [[nodiscard]] Result {
public:
using ResultType = Result<T, E>;
constexpr Result(const T& value) : m_value{value}
{
}
constexpr Result(const E& value) : m_value{value}
{
}
constexpr Result(T&& value) : m_value{std::move(value)}
{
}
constexpr Result(E&& value) : m_value{std::move(value)}
{
}
static constexpr ResultType okay(const T& okay)
{
return ResultType{okay};
}
static constexpr ResultType okay(T&& okay)
{
return ResultType{std::move(okay)};
}
static constexpr ResultType error(const E& error)
{
return ResultType{error};
}
static constexpr ResultType error(E&& error)
{
return ResultType{std::move(error)};
}
template <typename F>
static constexpr ResultType okay(const Result<T, F>& okayRes)
{
return ResultType{okayRes.getOkay()};
}
template <typename F>
static constexpr ResultType okay(Result<T, F>&& okayRes)
{
return ResultType{okayRes.takeOkay()};
}
template <typename U>
static constexpr ResultType error(const Result<U, E>& errorRes)
{
return ResultType{errorRes.getError()};
}
template <typename U>
static constexpr ResultType error(Result<U, E>&& errorRes)
{
return ResultType{errorRes.takeError()};
}
[[nodiscard]] constexpr bool isOkay() const
{
return (m_value.index() == 0);
}
[[nodiscard]] constexpr bool isError() const
{
return (m_value.index() == 1);
}
[[nodiscard]] constexpr const T& getOkay() const&
{
return std::get<T>(m_value);
}
[[nodiscard]] constexpr const E& getError() const&
{
return std::get<E>(m_value);
}
[[nodiscard]] constexpr T&& takeOkay()
{
return std::move(std::get<T>(m_value));
}
[[nodiscard]] constexpr E&& takeError()
{
return std::move(std::get<E>(m_value));
}
private:
constexpr Result() : m_value()
{
}
std::variant<T, E> m_value;
};
#define M_TakeOrReturn(HYGIENE_EXPRESSION) \
({ \
auto HYGIENE_RESULT{(HYGIENE_EXPRESSION)}; \
if (HYGIENE_RESULT.isError()) { \
return HYGIENE_RESULT.takeError(); \
} \
HYGIENE_RESULT.takeOkay(); \
})
} // namespace fud
#endif
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