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/*
* SPDX-License-Identifier: GPL-2.0-or-later
* SPDX-FileName: Result.h
* SPDX-FileContributor: Dmitry Vedenko
*/
#pragma once
#include <type_traits>
#include <variant>
#include "Error.h"
namespace audacity::sqlite
{
//! A class representing a result of an operation
template<typename T>
class Result final
{
public:
Result() = default;
Result(T&& value) noexcept(std::is_nothrow_move_constructible_v<T>)
: mValue (std::forward<T>(value))
{
}
Result (const Error& error) noexcept(std::is_nothrow_copy_constructible_v<Error>)
: mValue (error)
{
}
Result (Error&& error) noexcept(std::is_nothrow_move_constructible_v<Error>)
: mValue (std::move(error))
{
}
bool HasValue () const noexcept
{
return std::holds_alternative<T>(mValue);
}
T& operator* () &
{
if (!HasValue())
std::get_if<Error>(&mValue)->Raise();
return *std::get_if<T>(&mValue);
}
const T& operator*() const&
{
return const_cast<Result*>(this)->operator*();
}
T* operator-> ()
{
return &operator*();
}
const T* operator-> () const
{
return &operator*();
}
T&& operator* () &&
{
if (!HasValue())
std::get_if<Error>(&mValue)->Raise();
return std::move(*std::get_if<T>(&mValue));
}
explicit operator bool () const noexcept
{
return HasValue();
}
Error GetError () const noexcept
{
if (HasValue())
return Error();
return *std::get_if<Error>(&mValue);
}
private:
std::variant<Error, T> mValue;
};
} // namespace audacity::sqlite
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