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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 <utility>
#include <variant>
namespace fud {
namespace detail {
template <typename T>
class CopyMove {
public:
explicit constexpr CopyMove(T value) : m_value{std::move(value)}
{
}
constexpr T&& take()
{
return std::move(m_value);
}
constexpr T copy() const
{
return m_value;
}
private:
T m_value;
};
} // namespace detail
/** \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>;
static ResultType okay(const T& okay)
{
return ResultType{okay};
}
static ResultType okay(T&& okay)
{
return ResultType{std::move(okay)};
}
static ResultType error(const E& error)
{
return ResultType{error};
}
static ResultType error(E&& error)
{
return ResultType{std::move(error)};
}
[[nodiscard]] constexpr bool isOkay() const
{
return (m_value.index() == 0);
}
[[nodiscard]] constexpr bool isError() const
{
return (m_value.index() == 1);
}
[[nodiscard]] T getOkay() const
{
return std::get<detail::CopyMove<T>>(m_value).copy();
}
[[nodiscard]] E getError() const
{
return std::get<detail::CopyMove<E>>(m_value).copy();
}
[[nodiscard]] T&& getOkay()
{
return std::get<detail::CopyMove<T>>(m_value).take();
}
[[nodiscard]] E&& getError()
{
return std::get<detail::CopyMove<E>>(m_value).take();
}
private:
explicit Result() : m_value()
{
}
explicit Result(const T& value) : m_value{detail::CopyMove<T>{value}}
{
}
explicit Result(const E& value) : m_value{detail::CopyMove<E>{value}}
{
}
explicit Result(T&& value) : m_value{detail::CopyMove<T>{std::move(value)}}
{
}
explicit Result(E&& value) : m_value{detail::CopyMove<E>{std::move(value)}}
{
}
std::variant<detail::CopyMove<T>, detail::CopyMove<E>> m_value;
};
} // namespace fud
#endif
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