sol2/sol/call.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
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#ifndef SOL_CALL_HPP
#define SOL_CALL_HPP

#include "wrapper.hpp"
#include "property.hpp"
#include "stack.hpp"

namespace sol {
	namespace call_detail {

		template <bool b, typename F>
		inline decltype(auto) pick(std::integral_constant<bool, b>, F&& f) {
			return std::forward<F>(f);
		}

		template <typename R, typename W>
		inline auto& pick(std::true_type, property_wrapper<R, W>& f) {
			return f.read;
		}

		template <typename R, typename W>
		inline auto& pick(std::false_type, property_wrapper<R, W>& f) {
			return f.write;
		}

		template <typename T, typename List>
		struct void_call;

		template <typename T, typename... Args>
		struct void_call<T, types<Args...>> {
			static void call(Args...) {}
		};

		template <typename T, int additional_pop = 0>
		struct constructor_match {
			T* obj;

			constructor_match(T* obj) : obj(obj) {}

			template <typename Fx, std::size_t I, typename... R, typename... Args>
			int operator()(types<Fx>, index_value<I>, types<R...> r, types<Args...> a, lua_State* L, int, int start) const {
				detail::default_construct func{};
				return stack::call_into_lua<additional_pop, false>(r, a, L, start, func, obj);
			}
		};

		template <typename T>
		inline int destruct(lua_State* L) {
			T* obj = stack::get<non_null<T*>>(L, 1);
			std::allocator<T> alloc{};
			alloc.destroy(obj);
			return 0;
		}

		namespace overload_detail {
			template <std::size_t... M, typename Match, typename... Args>
			inline int overload_match_arity(sol::types<>, std::index_sequence<>, std::index_sequence<M...>, Match&&, lua_State* L, int, int, Args&&...) {
				return luaL_error(L, "sol: no matching function call takes this number of arguments and the specified types");
			}

			template <typename Fx, typename... Fxs, std::size_t I, std::size_t... In, std::size_t... M, typename Match, typename... Args>
			inline int overload_match_arity(sol::types<Fx, Fxs...>, std::index_sequence<I, In...>, std::index_sequence<M...>, Match&& matchfx, lua_State* L, int fxarity, int start, Args&&... args) {
				typedef lua_bind_traits<meta::unqualified_t<Fx>> traits;
				typedef meta::tuple_types<typename traits::return_type> return_types;
				typedef typename traits::free_args_list args_list;
				typedef typename args_list::indices args_indices;
				// compile-time eliminate any functions that we know ahead of time are of improper arity
				if (meta::find_in_pack_v<index_value<traits::free_arity>, index_value<M>...>::value) {
					return overload_match_arity(types<Fxs...>(), std::index_sequence<In...>(), std::index_sequence<M...>(), std::forward<Match>(matchfx), L, fxarity, start, std::forward<Args>(args)...);
				}
				if (traits::free_arity != fxarity) {
					return overload_match_arity(types<Fxs...>(), std::index_sequence<In...>(), std::index_sequence<traits::arity, M...>(), std::forward<Match>(matchfx), L, fxarity, start, std::forward<Args>(args)...);
				}
				if (!stack::stack_detail::check_types<true>().check(args_list(), args_indices(), L, start, no_panic)) {
					return overload_match_arity(types<Fxs...>(), std::index_sequence<In...>(), std::index_sequence<M...>(), std::forward<Match>(matchfx), L, fxarity, start, std::forward<Args>(args)...);
				}
				return matchfx(types<Fx>(), index_value<I>(), return_types(), args_list(), L, fxarity, start, std::forward<Args>(args)...);
			}
		} // overload_detail

		template <typename... Functions, typename Match, typename... Args>
		inline int overload_match_arity(Match&& matchfx, lua_State* L, int fxarity, int start, Args&&... args) {
			return overload_detail::overload_match_arity(types<Functions...>(), std::make_index_sequence<sizeof...(Functions)>(), std::index_sequence<>(), std::forward<Match>(matchfx), L, fxarity, start, std::forward<Args>(args)...);
		}

		template <typename... Functions, typename Match, typename... Args>
		inline int overload_match(Match&& matchfx, lua_State* L, int start, Args&&... args) {
			int fxarity = lua_gettop(L) - (start - 1);
			return overload_match_arity<Functions...>(std::forward<Match>(matchfx), L, fxarity, start, std::forward<Args>(args)...);
		}

		template <typename T, typename... TypeLists, typename Match, typename... Args>
		inline int construct(Match&& matchfx, lua_State* L, int fxarity, int start, Args&&... args) {
			// use same overload resolution matching as all other parts of the framework
			return overload_match_arity<decltype(void_call<T, TypeLists>::call)...>(std::forward<Match>(matchfx), L, fxarity, start, std::forward<Args>(args)...);
		}

		template <typename T, typename... TypeLists>
		inline int construct(lua_State* L) {
			static const auto& meta = usertype_traits<T>::metatable;
			int argcount = lua_gettop(L);
			call_syntax syntax = argcount > 0 ? stack::get_call_syntax(L, meta, 1) : call_syntax::dot;
			argcount -= static_cast<int>(syntax);

			T** pointerpointer = reinterpret_cast<T**>(lua_newuserdata(L, sizeof(T*) + sizeof(T)));
			T*& referencepointer = *pointerpointer;
			T* obj = reinterpret_cast<T*>(pointerpointer + 1);
			referencepointer = obj;
			reference userdataref(L, -1);
			userdataref.pop();

			construct<T, TypeLists...>(constructor_match<T>(obj), L, argcount, 1 + static_cast<int>(syntax));

			userdataref.push();
			luaL_getmetatable(L, &meta[0]);
			if (type_of(L, -1) == type::nil) {
				lua_pop(L, 1);
				return luaL_error(L, "sol: unable to get usertype metatable");
			}

			lua_setmetatable(L, -2);
			return 1;
		}

		template <typename F, bool is_index, bool is_variable, typename = void>
		struct agnostic_lua_call_wrapper {
			static int var_call(std::true_type, lua_State* L, F& f) {
				typedef wrapper<meta::unqualified_t<F>> wrap;
				typedef typename wrap::returns_list returns_list;
				typedef typename wrap::free_args_list args_list;
				typedef typename wrap::caller caller;
				return stack::call_into_lua<is_index ? 1 : 2>(returns_list(), args_list(), L, is_index ? 2 : 3, caller(), f);
			}

			static int var_call(std::false_type, lua_State* L, F& f) {
				typedef wrapper<meta::unqualified_t<F>> wrap;
				typedef typename wrap::free_args_list args_list;
				typedef typename wrap::returns_list returns_list;
				typedef typename wrap::caller caller;
				return stack::call_into_lua(returns_list(), args_list(), L, 1, caller(), f);
			}

			static int call(lua_State* L, F& f) {
				return var_call(std::integral_constant<bool, is_variable>(), L, f);
			}
		};

		template <typename F, bool is_index, bool is_variable>
		struct agnostic_lua_call_wrapper<F, is_index, is_variable, std::enable_if_t<std::is_member_function_pointer<F>::value>> {
			static int call(lua_State* L, F& f) {
				typedef wrapper<meta::unqualified_t<F>> wrap;
				typedef typename wrap::returns_list returns_list;
				typedef typename wrap::args_list args_list;
				typedef typename wrap::caller caller;
				typedef typename wrap::object_type object_type;

#ifdef SOL_SAFE_USERTYPE
				object_type* o = stack::get<object_type*>(L, 1);
				if (o == nullptr) {
					return luaL_error(L, "sol: received null for 'self' argument (use ':' for accessing member functions, make sure member variables are preceeded by the actual object with '.' syntax)");
				}
				return stack::call_into_lua<is_variable ? 2 : 1>(returns_list(), args_list(), L, is_variable ? 3 : 2, caller(), f, *o);
#else
				object_type& o = stack::get<object_type&>(L, 1);
				return stack::call_into_lua<is_variable ? 2 : 1>(returns_list(), args_list(), L, is_variable ? 3 : 2, caller(), f, o);
#endif // Safety
			}
		};

		template <bool is_index, bool is_variable, typename C>
		struct agnostic_lua_call_wrapper<lua_r_CFunction, is_index, is_variable, C> {
			static int call(lua_State* L, lua_r_CFunction f) {
				return f(L);
			}
		};

		template <bool is_index, bool is_variable, typename C>
		struct agnostic_lua_call_wrapper<lua_CFunction, is_index, is_variable, C> {
			static int call(lua_State* L, lua_CFunction f) {
				return f(L);
			}
		};

		template <bool is_index, bool is_variable, typename C>
		struct agnostic_lua_call_wrapper<no_prop, is_index, is_variable, C> {
			static int call(lua_State* L, no_prop&) {
				return luaL_error(L, is_index ? "sol: cannot read from a writeonly property" : "sol: cannot write to a readonly property");
			}
		};

		template <typename F, bool is_variable>
		struct agnostic_lua_call_wrapper<F, false, is_variable, std::enable_if_t<std::is_member_object_pointer<F>::value>> {
			typedef sol::lua_bind_traits<F> traits_type;

			static int call_assign(std::true_type, lua_State* L, F& f) {
				typedef wrapper<meta::unqualified_t<F>> wrap;
				typedef typename wrap::args_list args_list;
				typedef typename wrap::object_type object_type;
				typedef typename wrap::caller caller;
#ifdef SOL_SAFE_USERTYPE
				object_type* o = stack::get<object_type*>(L, 1);
				if (o == nullptr) {
					if (is_variable) {
						return luaL_error(L, "sol: received nil for 'self' argument (bad '.' access?)");
					}
					return luaL_error(L, "sol: received nil for 'self' argument (pass 'self' as first argument)");
				}
				return stack::call_into_lua<is_variable ? 2 : 1>(types<void>(), args_list(), L, is_variable ? 3 : 2, caller(), f, *o);
#else
				object_type& o = stack::get<object_type&>(L, 1);
				return stack::call_into_lua<is_variable ? 2 : 1>(types<void>(), args_list(), L, is_variable ? 3 : 2, caller(), f, o);
#endif // Safety
			}

			static int call_assign(std::false_type, lua_State* L, F&) {
				return luaL_error(L, "sol: cannot write to this variable: copy assignment/constructor not available");
			}

			static int call_const(std::false_type, lua_State* L, F& f) {
				typedef typename traits_type::return_type R;
				return call_assign(std::is_assignable<std::add_lvalue_reference_t<meta::unqualified_t<R>>, R>(), L, f);
			}

			static int call_const(std::true_type, lua_State* L, F&) {
				return luaL_error(L, "sol: cannot write to a readonly (const) variable");
			}

			static int call(lua_State* L, F& f) {
				return call_const(std::is_const<typename traits_type::return_type>(), L, f);
			}
		};

		template <typename F, bool is_variable>
		struct agnostic_lua_call_wrapper<F, true, is_variable, std::enable_if_t<std::is_member_object_pointer<F>::value>> {
			typedef sol::lua_bind_traits<F> traits_type;

			static int call(lua_State* L, F& f) {
				typedef wrapper<meta::unqualified_t<F>> wrap;
				typedef typename wrap::object_type object_type;
				typedef typename wrap::returns_list returns_list;
				typedef typename wrap::caller caller;
#ifdef SOL_SAFE_USERTYPE
				object_type* o = stack::get<object_type*>(L, 1);
				if (o == nullptr) {
					if (is_variable) {
						return luaL_error(L, "sol: 'self' argument is nil (bad '.' access?)");
					}
					return luaL_error(L, "sol: 'self' argument is nil (pass 'self' as first argument)");
				}
				return stack::call_into_lua<is_variable ? 2 : 1>(returns_list(), types<>(), L, is_variable ? 3 : 2, caller(), f, *o);
#else
				object_type& o = stack::get<object_type&>(L, 1);
				return stack::call_into_lua<is_variable ? 2 : 1>(returns_list(), types<>(), L, is_variable ? 3 : 2, caller(), f, o);
#endif // Safety
			}
		};

		template <bool is_index, bool is_variable, typename C>
		struct agnostic_lua_call_wrapper<no_construction, is_index, is_variable, C> {
			static int call(lua_State* L, no_construction&) {
				return luaL_error(L, "sol: cannot call this constructor (tagged as non-constructible)");
			}
		};

		template <typename... Args, bool is_index, bool is_variable, typename C>
		struct agnostic_lua_call_wrapper<bases<Args...>, is_index, is_variable, C> {
			static int call(lua_State*, bases<Args...>&) {
				// Uh. How did you even call this, lul
				return 0;
			}
		};

		template <typename T, typename F, bool is_index, bool is_variable, typename = void>
		struct lua_call_wrapper : agnostic_lua_call_wrapper<F, is_index, is_variable> {};

		template <typename T, typename... Args, bool is_index, bool is_variable, typename C>
		struct lua_call_wrapper<T, sol::constructor_list<Args...>, is_index, is_variable, C> {
			typedef sol::constructor_list<Args...> F;

			static int call(lua_State* L, F&) {
				const auto& metakey = usertype_traits<T>::metatable;
				int argcount = lua_gettop(L);
				call_syntax syntax = argcount > 0 ? stack::get_call_syntax(L, metakey, 1) : call_syntax::dot;
				argcount -= static_cast<int>(syntax);

				T** pointerpointer = reinterpret_cast<T**>(lua_newuserdata(L, sizeof(T*) + sizeof(T)));
				reference userdataref(L, -1);
				T*& referencepointer = *pointerpointer;
				T* obj = reinterpret_cast<T*>(pointerpointer + 1);
				referencepointer = obj;

				construct<T, Args...>(constructor_match<T, 1>(obj), L, argcount, 1 + static_cast<int>(syntax));

				userdataref.push();
				luaL_getmetatable(L, &metakey[0]);
				if (type_of(L, -1) == type::nil) {
					lua_pop(L, 1);
					return luaL_error(L, "sol: unable to get usertype metatable");
				}

				lua_setmetatable(L, -2);
				return 1;
			}
		};

		template <typename T, typename... Cxs, bool is_index, bool is_variable, typename C>
		struct lua_call_wrapper<T, sol::constructor_wrapper<Cxs...>, is_index, is_variable, C> {
			typedef sol::constructor_wrapper<Cxs...> F;

			struct onmatch {
				template <typename Fx, std::size_t I, typename... R, typename... Args>
				int operator()(types<Fx>, index_value<I>, types<R...> r, types<Args...> a, lua_State* L, int, int start, F& f) {
					const auto& metakey = usertype_traits<T>::metatable;
					T** pointerpointer = reinterpret_cast<T**>(lua_newuserdata(L, sizeof(T*) + sizeof(T)));
					reference userdataref(L, -1);
					T*& referencepointer = *pointerpointer;
					T* obj = reinterpret_cast<T*>(pointerpointer + 1);
					referencepointer = obj;

					auto& func = std::get<I>(f.set);
					stack::call_into_lua<1, false>(r, a, L, start, func, detail::implicit_wrapper<T>(obj));

					userdataref.push();
					luaL_getmetatable(L, &metakey[0]);
					if (type_of(L, -1) == type::nil) {
						lua_pop(L, 1);
						std::string err = "sol: unable to get usertype metatable for ";
						err += usertype_traits<T>::name;
						return luaL_error(L, err.c_str());
					}
					lua_setmetatable(L, -2);

					return 1;
				}
			};

			static int call(lua_State* L, F& f) {
				call_syntax syntax = stack::get_call_syntax(L, usertype_traits<T>::metatable);
				int syntaxval = static_cast<int>(syntax);
				int argcount = lua_gettop(L) - syntaxval;
				return construct<T, meta::pop_front_type_t<meta::function_args_t<Cxs>>...>(onmatch(), L, argcount, 1 + syntaxval, f);
			}

		};

		template <typename T, typename Fx, bool is_index, bool is_variable>
		struct lua_call_wrapper<T, sol::destructor_wrapper<Fx>, is_index, is_variable, std::enable_if_t<std::is_void<Fx>::value>> {
			typedef sol::destructor_wrapper<Fx> F;

			static int call(lua_State* L, F&) {
				return destruct<T>(L);
			}
		};

		template <typename T, typename Fx, bool is_index, bool is_variable>
		struct lua_call_wrapper<T, sol::destructor_wrapper<Fx>, is_index, is_variable, std::enable_if_t<!std::is_void<Fx>::value>> {
			typedef sol::destructor_wrapper<Fx> F;

			static int call(lua_State* L, F& f) {
				T* obj = stack::get<non_null<T*>>(L);
				f.fx(detail::implicit_wrapper<T>(obj));
				return 0;
			}
		};

		template <typename T, typename... Fs, bool is_index, bool is_variable, typename C>
		struct lua_call_wrapper<T, overload_set<Fs...>, is_index, is_variable, C> {
			typedef overload_set<Fs...> F;

			struct on_match {
				template <typename Fx, std::size_t I, typename... R, typename... Args>
				int operator()(types<Fx>, index_value<I>, types<R...>, types<Args...>, lua_State* L, int, int, F& fx) {
					auto& f = std::get<I>(fx.set);
					return lua_call_wrapper<T, Fx, is_index, is_variable>{}.call(L, f);
				}
			};

			static int call(lua_State* L, F& fx) {
				return overload_match_arity<Fs...>(on_match(), L, lua_gettop(L), 1, fx);
			}
		};

		template <typename T, bool is_index, bool is_variable, typename Fx>
		int call_wrapped(lua_State* L, Fx&& fx) {
			return lua_call_wrapper<T, meta::unqualified_t<Fx>, is_index, is_variable>{}.call(L, std::forward<Fx>(fx));
		}

		template <typename T, typename = void>
		struct is_var_bind : std::false_type {};

		template <typename T>
		struct is_var_bind<T, std::enable_if_t<std::is_member_object_pointer<T>::value>> : std::true_type {};

		template <>
		struct is_var_bind<no_prop> : std::true_type {};

		template <typename R, typename W>
		struct is_var_bind<property_wrapper<R, W>> : std::true_type {};

	} // call_detail

	template <typename T>
	struct is_variable_binding : call_detail::is_var_bind<meta::unqualified_t<T>> {};

	template <typename T>
	struct is_function_binding : meta::neg<is_variable_binding<T>> {};

} // sol

#endif // SOL_CALL_HPP