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// Copyright 2018 Dolphin Emulator Project
// SPDX-License-Identifier: GPL-2.0-or-later
#pragma once
#include <variant>
namespace detail
{
template <typename... From>
struct VariantCastProxy
{
const std::variant<From...>& v;
template <typename... To>
operator std::variant<To...>() const
{
return std::visit([](auto&& arg) { return std::variant<To...>{arg}; }, v);
}
};
} // namespace detail
template <typename... From>
auto VariantCast(const std::variant<From...>& v)
{
return detail::VariantCastProxy<From...>{v};
}
template <class... Ts>
struct overloaded : Ts...
{
using Ts::operator()...;
};
template <class... Ts>
overloaded(Ts...) -> overloaded<Ts...>;
// Visits a functor with a variant_alternative of the given index.
// e.g. WithVariantAlternative<variant<int, float>>(1, func) calls func<float>()
// An out-of-bounds index causes no visitation.
template <typename Variant, std::size_t I = 0, typename Func>
void WithVariantAlternative(std::size_t index, Func&& func)
{
if constexpr (I < std::variant_size_v<Variant>)
{
if (index == 0)
func.template operator()<std::variant_alternative_t<I, Variant>>();
else
WithVariantAlternative<Variant, I + 1>(index - 1, std::forward<Func>(func));
}
}
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