sol2/sol/function.hpp

// The MIT License (MIT)

// Copyright (c) 2013 Danny Y., Rapptz

// Permission is hereby granted, free of charge, to any person obtaining a copy of
// this software and associated documentation files (the "Software"), to deal in
// the Software without restriction, including without limitation the rights to
// use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
// the Software, and to permit persons to whom the Software is furnished to do so,
// subject to the following conditions:

// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.

// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
// FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
// COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
// IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
// CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

#ifndef SOL_FUNCTION_HPP
#define SOL_FUNCTION_HPP

#include "reference.hpp"
#include "tuple.hpp"
#include "stack.hpp"

namespace sol {
class function : virtual public reference {
private:
    template<typename... Args>
    void push_args(Args&&... args) const {
        auto L = state();
        using swallow = char[ ];
        void(swallow{ (stack::push(L, std::forward<Args>(args)), '\0')... });
    }

    template<typename... Ret>
    struct invoker {
        template<typename... Args>
        static std::tuple<Ret...> call(const function& ref, Args&&... args) {
            ref.push();
            ref.push_args(std::forward<Args>(args)...);
            lua_pcall(ref.state(), sizeof...(Args), sizeof...(Ret), 0);
            return std::make_tuple(stack::pop<Ret>(ref.state())...);
        }
    };

    template<>
    struct invoker<> {
        template<typename... Args>
        static void call(const function& ref, Args&&... args) {
            ref.push();
            ref.push_args(std::forward<Args>(args)...);
            lua_pcall(ref.state(), sizeof...(Args), 0, 0);
        }
    };

    template<typename T>
    struct invoker<T> {
        template<typename... Args>
        static T call(const function& ref, Args&&... args) {
            ref.push();
            ref.push_args(std::forward<Args>(args)...);
            lua_pcall(ref.state(), sizeof...(Args), 1, 0);
            return stack::pop<T>(ref.state());
        }
    };

public:
    function() : reference() {}
    function(lua_State* L, int index = -1) : reference(L, index) {
        type_assert(L, index, type::function);
    }

    template<typename... Ret, typename... Args>
    auto invoke(Args&&... args) {
        return invoker<Ret...>::call(*this, std::forward<Args>(args)...);
    }
};
} // sol

#endif // SOL_FUNCTION_HPP