function.h

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// =====================================================================================================================
//  fennec, a free and open source game engine
//  Copyright © 2025  Medusa Slockbower
//
//  This program is free software: you can redistribute it and/or modify
//  it under the terms of the GNU General Public License as published by
//  the Free Software Foundation, either version 3 of the License, or
//  (at your option) any later version.
//
//  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 <https://www.gnu.org/licenses/>.
// =====================================================================================================================
 
 
 
#ifndef FENNEC_LANG_FUNCTION_H
#define FENNEC_LANG_FUNCTION_H
 
#include <fennec/lang/types.h>
#include <fennec/lang/assert.h>
#include <fennec/lang/utility.h>
 
#include <fennec/lang/detail/_function.h>
 
namespace fennec
{
 
template<typename> class function;
 
template<typename ReturnT, typename...ArgsT>
class function<ReturnT(ArgsT...)> {
public:
    constexpr function() noexcept = default;
    constexpr ~function() = default;
 
    constexpr function(const function&)  noexcept = default;
    constexpr function(      function&&) noexcept = default;
 
    constexpr function(ReturnT (*func)(ArgsT...))
        : call(func) {
    }
 
    constexpr function(nullptr_t) noexcept : function() {}
 
    constexpr function& operator=(const function&) = default;
    constexpr function& operator=(function&&)      = default;
 
    constexpr function& operator=(nullptr_t) {
        call = nullptr;
        return *this;
    }
 
    constexpr function& operator=(ReturnT (*func)(ArgsT...)) {
        call = func;
        return *this;
    }
 
    constexpr operator bool() const noexcept { return call != nullptr; }
 
    ReturnT operator()(ArgsT...args) const noexcept {
        assertf(call != nullptr, "Attempted to call a null function object!");
        return call(fennec::forward<ArgsT>(args)...);
    }
 
private:
    ReturnT (*call)(ArgsT&&...) { nullptr };
};
 
}
 
#endif // FENNEC_LANG_FUNCTION_H