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/*
 * Copyright © Canonical Ltd.
 *
 * This program is free software: you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 or 3 as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#ifndef MIRAL_LAMBDA_AS_FUNCTION_H
#define MIRAL_LAMBDA_AS_FUNCTION_H

#include <functional>
#include <type_traits>
#include <utility>

namespace miral
{
namespace detail
{
template<class F>
struct FunctionType;

template<typename Lambda, typename Return, typename... Arg>
struct FunctionType<Return (Lambda::*)(Arg...)>
{
    using type = std::function<Return(Arg...)>;
};

template<typename Lambda, typename Return, typename... Arg>
struct FunctionType<Return (Lambda::*)(Arg...) const>
{
    using type = std::function<Return(Arg...)>;
};
}

template<typename Lambda>
    requires requires { &std::remove_reference_t<Lambda>::operator(); }
auto lambda_as_function(Lambda&& lambda) ->
    typename detail::FunctionType<decltype(&std::remove_reference_t<Lambda>::operator())>::type
{
    return typename detail::FunctionType<decltype(&std::remove_reference_t<Lambda>::operator())>::type(
        std::forward<Lambda>(lambda));
}
}

#endif //MIRAL_LAMBDA_AS_FUNCTION_H