sol2/sol/environment.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
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#ifndef SOL_ENVIRONMENT_HPP
#define SOL_ENVIRONMENT_HPP

#include "table.hpp"

namespace sol {

	template <typename base_type>
	struct basic_environment : basic_table<base_type> {
	private:
		typedef basic_table<base_type> table_t;
	public:
		basic_environment() noexcept = default;
		basic_environment(const basic_environment&) = default;
		basic_environment(basic_environment&&) = default;
		basic_environment& operator=(const basic_environment&) = default;
		basic_environment& operator=(basic_environment&&) = default;
		
		basic_environment(env_t, const stack_reference& extraction_target) : table_t(extraction_target.lua_state(), (stack::push_environment_of(extraction_target), -1)) {
			lua_pop(this->lua_state(), 2);
		}
		basic_environment(env_t, const reference& extraction_target) : table_t(extraction_target.lua_state(), (stack::push_environment_of(extraction_target), -1)) {
			lua_pop(this->lua_state(), 2);
		}

		basic_environment(lua_State* L, new_table t, const reference& fallback) : table_t(L, std::move(t)) {
			sol::stack_table mt(L, sol::new_table(0, 1));
			mt.set(sol::meta_function::index, fallback);
			this->set(metatable_key, mt);
			mt.pop();
		}
		
		template <typename T, typename... Args, meta::enable<
			meta::neg<std::is_same<meta::unqualified_t<T>, basic_environment>>, 
			meta::boolean<!(sizeof...(Args) == 2 && meta::any_same<new_table, meta::unqualified_t<Args>...>::value)>,
			meta::boolean<!(sizeof...(Args) == 1 && std::is_same<env_t, meta::unqualified_t<T>>::value)>,
			meta::boolean<!(sizeof...(Args) == 0 && std::is_base_of<proxy_base_tag, meta::unqualified_t<T>>::value)>
		> = meta::enabler>
		basic_environment(T&& arg, Args&&... args) : table_t(std::forward<T>(arg), std::forward<Args>(args)...) { }

		template <typename T>
		void set_on(const T& target) const {
			lua_State* L = target.lua_state();
			auto pp = stack::push_pop(target);
#if SOL_LUA_VERSION < 502
			// Use lua_setfenv
			this->push();
			lua_setfenv(L, -2);
#else
			// Use upvalues as explained in Lua 5.2 and beyond's manual
			this->push();
			if (lua_setupvalue(L, -2, 1) == nullptr) {
				this->pop();
			}
#endif
		}
	};

	template <typename T, typename E>
	void set_environment(const basic_environment<E>& env, const T& target) {
		env.set_on(target);
	}

	template <typename E = reference, typename T>
	basic_environment<E> get_environment(const T& target) {
		lua_State* L = target.lua_state();
		auto pp = stack::pop_n(L, stack::push_environment_of(target));
		return basic_environment<E>(L, -1);
	}

	namespace stack {
		template <>
		struct getter<env_t> {
			static environment get(lua_State* L, int index = -1) {
				return get_environment(stack_reference(L, raw_index(index)));
			}
		};
	} // stack
} // sol

#endif // SOL_ENVIRONMENT_HPP