sol2/sol/function.hpp

// The MIT License (MIT) 

// Copyright (c) 2013-2016 Rapptz, ThePhD and contributors

// 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 "stack.hpp"
#include "resolve.hpp"
#include "function_result.hpp"
#include "function_types.hpp"
#include <cstdint>
#include <functional>
#include <memory>

namespace sol {
template <typename base_t>
class basic_function : public base_t {
private:
    void luacall( std::ptrdiff_t argcount, std::ptrdiff_t resultcount ) const {
        lua_callk( base_t::lua_state( ), static_cast<int>( argcount ), static_cast<int>( resultcount ), 0, nullptr );
    }

    template<std::size_t... I, typename... Ret>
    auto invoke( types<Ret...>, std::index_sequence<I...>, std::ptrdiff_t n ) const {
        luacall( n, sizeof...( Ret ) );
        return stack::pop<std::tuple<Ret...>>( base_t::lua_state( ) );
    }

    template<std::size_t I, typename Ret>
    Ret invoke(types<Ret>, std::index_sequence<I>, std::ptrdiff_t n ) const {
        luacall( n, 1 );
        return stack::pop<Ret>( base_t::lua_state( ) );
    }

    template <std::size_t I>
    void invoke(types<void>, std::index_sequence<I>, std::ptrdiff_t n) const {
        luacall( n, 0 );
    }

    function_result invoke(types<>, std::index_sequence<>, std::ptrdiff_t n ) const {
        int stacksize = lua_gettop( base_t::lua_state( ) );
        int firstreturn = std::max( 1, stacksize - static_cast<int>( n ) );
        luacall(n, LUA_MULTRET);
        int poststacksize = lua_gettop( base_t::lua_state( ) );
        int returncount = poststacksize - (firstreturn - 1);
        return function_result( base_t::lua_state( ), firstreturn, returncount );
    }

public:
    basic_function() = default;
    basic_function(const basic_function&) = default;
    basic_function& operator=(const basic_function&) = default;
    basic_function(basic_function&& ) = default;
    basic_function& operator=(basic_function&& ) = default;
    basic_function(lua_State* L, int index = -1): base_t(L, index) {
#ifdef SOL_CHECK_ARGUMENTS
        type_assert(L, index, type::function);
#endif // Safety
    }
    
    template<typename... Args>
    function_result operator()( Args&&... args ) const {
        return call<>( std::forward<Args>( args )... );
    }

    template<typename... Ret, typename... Args>
    decltype(auto) operator()( types<Ret...>, Args&&... args ) const {
        return call<Ret...>( std::forward<Args>( args )... );
    }

    template<typename... Ret, typename... Args>
    decltype(auto) call( Args&&... args ) const {
        base_t::push( );
        int pushcount = stack::multi_push( base_t::lua_state( ), std::forward<Args>( args )... );
        return invoke( types<Ret...>( ), std::make_index_sequence<sizeof...(Ret)>(), pushcount );
    }
};

namespace stack {
template<typename Signature>
struct getter<std::function<Signature>> {
    typedef meta::bind_traits<Signature> fx_t;
    typedef typename fx_t::args_type args_types;
    typedef meta::tuple_types<typename fx_t::return_type> return_types;

    template<typename... Args, typename... Ret>
    static std::function<Signature> get_std_func(types<Ret...>, types<Args...>, lua_State* L, int index = -1) {
        sol::function f(L, index);
        auto fx = [f, L, index](Args&&... args) -> meta::return_type_t<Ret...> {
            return f.call<Ret...>(std::forward<Args>(args)...);
        };
        return std::move(fx);
    }

    template<typename... FxArgs>
    static std::function<Signature> get_std_func(types<void>, types<FxArgs...>, lua_State* L, int index = -1) {
        sol::function f(L, index);
        auto fx = [f, L, index](FxArgs&&... args) -> void {
            f(std::forward<FxArgs>(args)...);
        };
        return std::move(fx);
    }

    template<typename... FxArgs>
    static std::function<Signature> get_std_func(types<>, types<FxArgs...> t, lua_State* L, int index = -1) {
        return get_std_func(types<void>(), t, L, index);
    }

    static std::function<Signature> get(lua_State* L, int index) {
        return get_std_func(return_types(), args_types(), L, index);
    }
};
} // stack
} // sol

#endif // SOL_FUNCTION_HPP