sol2/sol/unsafe_function.hpp

// The MIT License (MIT) 

// Copyright (c) 2013-2017 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
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// the Software, and to permit persons to whom the Software is furnished to do so,
// subject to the following conditions:

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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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#ifndef SOL_UNSAFE_FUNCTION_HPP
#define SOL_UNSAFE_FUNCTION_HPP

#include "reference.hpp"
#include "stack.hpp"
#include "function_result.hpp"
#include "function_types.hpp"
#include <cstdint>

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, lua_size<std::tuple<Ret...>>::value);
			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, lua_size<Ret>::value);
			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;
		template <typename T, meta::enable<meta::neg<std::is_same<meta::unqualified_t<T>, basic_function>>, meta::neg<std::is_same<base_t, stack_reference>>, std::is_base_of<base_t, meta::unqualified_t<T>>> = meta::enabler>
		basic_function(T&& r) noexcept : base_t(std::forward<T>(r)) {
#ifdef SOL_CHECK_ARGUMENTS
			if (!is_function<meta::unqualified_t<T>>::value) {
				auto pp = stack::push_pop(*this);
				stack::check<basic_function>(base_t::lua_state(), -1, type_panic);
			}
#endif // Safety
		}
		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(const stack_reference& r) : basic_function(r.lua_state(), r.stack_index()) {}
		basic_function(stack_reference&& r) : basic_function(r.lua_state(), r.stack_index()) {}
		template <typename T, meta::enable<meta::neg<std::is_integral<meta::unqualified_t<T>>>, meta::neg<std::is_same<T, ref_index>>> = meta::enabler>
		basic_function(lua_State* L, T&& r) : basic_function(L, sol::ref_index(r.registry_index())) {}
		basic_function(lua_State* L, int index = -1) : base_t(L, index) {
#ifdef SOL_CHECK_ARGUMENTS
			stack::check<basic_function>(L, index, type_panic);
#endif // Safety
		}
		basic_function(lua_State* L, ref_index index) : base_t(L, index) {
#ifdef SOL_CHECK_ARGUMENTS
			auto pp = stack::push_pop(*this);
			stack::check<basic_function>(L, -1, type_panic);
#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_reference(base_t::lua_state(), std::forward<Args>(args)...);
			return invoke(types<Ret...>(), std::make_index_sequence<sizeof...(Ret)>(), pushcount);
		}
	};
} // sol

#endif // SOL_UNSAFE_FUNCTION_HPP