text: // sol3
  
  // The MIT License (MIT)
  
  // Copyright (c) 2013-2020 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_PROTECTED_FUNCTION_HPP
  #define SOL_PROTECTED_FUNCTION_HPP
  
  #include <sol/reference.hpp>
  #include <sol/object.hpp>
  #include <sol/stack.hpp>
  #include <sol/protected_function_result.hpp>
  #include <sol/unsafe_function.hpp>
  #include <sol/protected_handler.hpp>
  #include <sol/bytecode.hpp>
  #include <sol/dump_handler.hpp>
  
  #include <cstdint>
  #include <algorithm>
  
  namespace sol {
  
  	namespace detail {
  		template <bool b, typename handler_t>
  		inline void handle_protected_exception(
  		     lua_State* L, optional<const std::exception&> maybe_ex, const char* error, detail::protected_handler<b, handler_t>& h) {
  			h.stackindex = 0;
  			if (b) {
  				h.target.push();
  				detail::call_exception_handler(L, maybe_ex, error);
  				lua_call(L, 1, 1);
  			}
  			else {
  				detail::call_exception_handler(L, maybe_ex, error);
  			}
  		}
  	} // namespace detail
  
  	template <typename ref_t, bool aligned = false, typename handler_t = reference>
  	class basic_protected_function : public basic_object<ref_t> {
  	private:
  		using base_t = basic_object<ref_t>;
  
  	public:
  		using is_stack_handler = is_stack_based<handler_t>;
  
  		static handler_t get_default_handler(lua_State* L) {
  			return detail::get_default_handler<handler_t, is_main_threaded<base_t>::value>(L);
  		}
  
  		template <typename T>
  		static void set_default_handler(const T& ref) {
  			detail::set_default_handler(ref.lua_state(), ref);
  		}
  
  	private:
  		template <bool b>
  		call_status luacall(std::ptrdiff_t argcount, std::ptrdiff_t resultcount, detail::protected_handler<b, handler_t>& h) const {
  			return static_cast<call_status>(lua_pcall(lua_state(), static_cast<int>(argcount), static_cast<int>(resultcount), h.stackindex));
  		}
  
  		template <std::size_t... I, bool b, typename... Ret>
  		auto invoke(types<Ret...>, std::index_sequence<I...>, std::ptrdiff_t n, detail::protected_handler<b, handler_t>& h) const {
  			luacall(n, sizeof...(Ret), h);
  			return stack::pop<std::tuple<Ret...>>(lua_state());
  		}
  
  		template <std::size_t I, bool b, typename Ret>
  		Ret invoke(types<Ret>, std::index_sequence<I>, std::ptrdiff_t n, detail::protected_handler<b, handler_t>& h) const {
  			luacall(n, 1, h);
  			return stack::pop<Ret>(lua_state());
  		}
  
  		template <std::size_t I, bool b>
  		void invoke(types<void>, std::index_sequence<I>, std::ptrdiff_t n, detail::protected_handler<b, handler_t>& h) const {
  			luacall(n, 0, h);
  		}
  
  		template <bool b>
  		protected_function_result invoke(types<>, std::index_sequence<>, std::ptrdiff_t n, detail::protected_handler<b, handler_t>& h) const {
  			int stacksize = lua_gettop(lua_state());
  			int poststacksize = stacksize;
  			int firstreturn = 1;
  			int returncount = 0;
  			call_status code = call_status::ok;
  #if SOL_IS_ON(SOL_EXCEPTIONS_I_) && SOL_IS_OFF(SOL_PROPAGATE_EXCEPTIONS_I_)
  			try {
  #endif // No Exceptions
  				firstreturn = (std::max)(1, static_cast<int>(stacksize - n - static_cast<int>(h.valid() && !is_stack_handler::value)));
  				code = luacall(n, LUA_MULTRET, h);
  				poststacksize = lua_gettop(lua_state()) - static_cast<int>(h.valid() && !is_stack_handler::value);
  				returncount = poststacksize - (firstreturn - 1);
  #if SOL_IS_ON(SOL_EXCEPTIONS_I_) && SOL_IS_OFF(SOL_PROPAGATE_EXCEPTIONS_I_)
  			}
  			// Handle C++ errors thrown from C++ functions bound inside of lua
  			catch (const char* error) {
  				detail::handle_protected_exception(lua_state(), optional<const std::exception&>(nullopt), error, h);
  				firstreturn = lua_gettop(lua_state());
  				return protected_function_result(lua_state(), firstreturn, 0, 1, call_status::runtime);
  			}
  			catch (const std::string& error) {
  				detail::handle_protected_exception(lua_state(), optional<const std::exception&>(nullopt), error.c_str(), h);
  				firstreturn = lua_gettop(lua_state());
  				return protected_function_result(lua_state(), firstreturn, 0, 1, call_status::runtime);
  			}
  			catch (const std::exception& error) {
  				detail::handle_protected_exception(lua_state(), optional<const std::exception&>(error), error.what(), h);
  				firstreturn = lua_gettop(lua_state());
  				return protected_function_result(lua_state(), firstreturn, 0, 1, call_status::runtime);
  			}
  #if SOL_IS_ON(SOL_EXCEPTIONS_CATCH_ALL_I_)
  			// LuaJIT cannot have the catchall when the safe propagation is on
  			// but LuaJIT will swallow all C++ errors
  			// if we don't at least catch std::exception ones
  			catch (...) {
  				detail::handle_protected_exception(lua_state(), optional<const std::exception&>(nullopt), detail::protected_function_error, h);
  				firstreturn = lua_gettop(lua_state());
  				return protected_function_result(lua_state(), firstreturn, 0, 1, call_status::runtime);
  			}
  #endif // Always catch edge case
  #else
  			// do not handle exceptions: they can be propogated into C++ and keep all type information / rich information
  #endif // Exceptions vs. No Exceptions
  			return protected_function_result(lua_state(), firstreturn, returncount, returncount, code);
  		}
  
  	public:
  		using base_t::lua_state;
  
  		handler_t error_handler;
  
  		basic_protected_function() = default;
  		template <typename T,
  		     meta::enable<meta::neg<std::is_same<meta::unqualified_t<T>, basic_protected_function>>,
  		          meta::neg<std::is_base_of<proxy_base_tag, meta::unqualified_t<T>>>, meta::neg<std::is_same<base_t, stack_reference>>,
  		          meta::neg<std::is_same<lua_nil_t, meta::unqualified_t<T>>>, is_lua_reference<meta::unqualified_t<T>>> = meta::enabler>
  		basic_protected_function(T&& r) noexcept : base_t(std::forward<T>(r)), error_handler(get_default_handler(r.lua_state())) {
  #if SOL_IS_ON(SOL_SAFE_REFERENCES_I_)
  			if (!is_function<meta::unqualified_t<T>>::value) {
  				auto pp = stack::push_pop(*this);
  				constructor_handler handler {};
  				stack::check<basic_protected_function>(lua_state(), -1, handler);
  			}
  #endif // Safety
  		}
  		basic_protected_function(const basic_protected_function&) = default;
  		basic_protected_function& operator=(const basic_protected_function&) = default;
  		basic_protected_function(basic_protected_function&&) = default;
  		basic_protected_function& operator=(basic_protected_function&&) = default;
  		basic_protected_function(const basic_function<base_t>& b) : basic_protected_function(b, get_default_handler(b.lua_state())) {
  		}
  		basic_protected_function(basic_function<base_t>&& b) : basic_protected_function(std::move(b), get_default_handler(b.lua_state())) {
  		}
  		basic_protected_function(const basic_function<base_t>& b, handler_t eh) : base_t(b), error_handler(std::move(eh)) {
  		}
  		basic_protected_function(basic_function<base_t>&& b, handler_t eh) : base_t(std::move(b)), error_handler(std::move(eh)) {
  		}
  		basic_protected_function(const stack_reference& r) : basic_protected_function(r.lua_state(), r.stack_index(), get_default_handler(r.lua_state())) {
  		}
  		basic_protected_function(stack_reference&& r) : basic_protected_function(r.lua_state(), r.stack_index(), get_default_handler(r.lua_state())) {
  		}
  		basic_protected_function(const stack_reference& r, handler_t eh) : basic_protected_function(r.lua_state(), r.stack_index(), std::move(eh)) {
  		}
  		basic_protected_function(stack_reference&& r, handler_t eh) : basic_protected_function(r.lua_state(), r.stack_index(), std::move(eh)) {
  		}
  
  		template <typename Super>
  		basic_protected_function(const proxy_base<Super>& p) : basic_protected_function(p, get_default_handler(p.lua_state())) {
  		}
  		template <typename Super>
  		basic_protected_function(proxy_base<Super>&& p) : basic_protected_function(std::move(p), get_default_handler(p.lua_state())) {
  		}
  		template <typename Proxy, typename Handler,
  		     meta::enable<std::is_base_of<proxy_base_tag, meta::unqualified_t<Proxy>>, meta::neg<is_lua_index<meta::unqualified_t<Handler>>>> = meta::enabler>
  		basic_protected_function(Proxy&& p, Handler&& eh) : basic_protected_function(detail::force_cast<base_t>(p), std::forward<Handler>(eh)) {
  		}
  
  		template <typename T, meta::enable<is_lua_reference<meta::unqualified_t<T>>> = meta::enabler>
  		basic_protected_function(lua_State* L, T&& r) : basic_protected_function(L, std::forward<T>(r), get_default_handler(L)) {
  		}
  		template <typename T, meta::enable<is_lua_reference<meta::unqualified_t<T>>> = meta::enabler>
  		basic_protected_function(lua_State* L, T&& r, handler_t eh) : base_t(L, std::forward<T>(r)), error_handler(std::move(eh)) {
  #if SOL_IS_ON(SOL_SAFE_REFERENCES_I_)
  			auto pp = stack::push_pop(*this);
  			constructor_handler handler {};
  			stack::check<basic_protected_function>(lua_state(), -1, handler);
  #endif // Safety
  		}
  
  		basic_protected_function(lua_nil_t n) : base_t(n), error_handler(n) {
  		}
  
  		basic_protected_function(lua_State* L, int index = -1) : basic_protected_function(L, index, get_default_handler(L)) {
  		}
  		basic_protected_function(lua_State* L, int index, handler_t eh) : base_t(L, index), error_handler(std::move(eh)) {
  #if SOL_IS_ON(SOL_SAFE_REFERENCES_I_)
  			constructor_handler handler {};
  			stack::check<basic_protected_function>(L, index, handler);
  #endif // Safety
  		}
  		basic_protected_function(lua_State* L, absolute_index index) : basic_protected_function(L, index, get_default_handler(L)) {
  		}
  		basic_protected_function(lua_State* L, absolute_index index, handler_t eh) : base_t(L, index), error_handler(std::move(eh)) {
  #if SOL_IS_ON(SOL_SAFE_REFERENCES_I_)
  			constructor_handler handler {};
  			stack::check<basic_protected_function>(L, index, handler);
  #endif // Safety
  		}
  		basic_protected_function(lua_State* L, raw_index index) : basic_protected_function(L, index, get_default_handler(L)) {
  		}
  		basic_protected_function(lua_State* L, raw_index index, handler_t eh) : base_t(L, index), error_handler(std::move(eh)) {
  #if SOL_IS_ON(SOL_SAFE_REFERENCES_I_)
  			constructor_handler handler {};
  			stack::check<basic_protected_function>(L, index, handler);
  #endif // Safety
  		}
  		basic_protected_function(lua_State* L, ref_index index) : basic_protected_function(L, index, get_default_handler(L)) {
  		}
  		basic_protected_function(lua_State* L, ref_index index, handler_t eh) : base_t(L, index), error_handler(std::move(eh)) {
  #if SOL_IS_ON(SOL_SAFE_REFERENCES_I_)
  			auto pp = stack::push_pop(*this);
  			constructor_handler handler {};
  			stack::check<basic_protected_function>(lua_state(), -1, handler);
  #endif // Safety
  		}
  
  		template <typename Fx>
  		int dump(lua_Writer writer, void* userdata, bool strip, Fx&& on_error) const {
  			this->push();
  			auto ppn = stack::push_popper_n<false>(this->lua_state(), 1);
  			int r = lua_dump(this->lua_state(), writer, userdata, strip ? 1 : 0);
  			if (r != 0) {
  				return on_error(this->lua_state(), r, writer, userdata, strip);
  			}
  			return r;
  		}
  
  		int dump(lua_Writer writer, void* userdata, bool strip = false) const {
  			return dump(writer, userdata, strip, &dump_pass_on_error);
  		}
  
  		template <typename Container = bytecode>
  		Container dump() const {
  			Container bc;
  			(void)dump(static_cast<lua_Writer>(&basic_insert_dump_writer<Container>), static_cast<void*>(&bc), false, &dump_throw_on_error);
  			return bc;
  		}
  
  		template <typename Container = bytecode, typename Fx>
  		Container dump(Fx&& on_error) const {
  			Container bc;
  			(void)dump(static_cast<lua_Writer>(&basic_insert_dump_writer<Container>), static_cast<void*>(&bc), false, std::forward<Fx>(on_error));
  			return bc;
  		}
  
  		template <typename... Args>
  		protected_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 {
  			if constexpr (!aligned) {
  				// we do not expect the function to already be on the stack: push it
  				if (error_handler.valid()) {
  					detail::protected_handler<true, handler_t> h(error_handler);
  					base_t::push();
  					int pushcount = stack::multi_push_reference(lua_state(), std::forward<Args>(args)...);
  					return invoke(types<Ret...>(), std::make_index_sequence<sizeof...(Ret)>(), pushcount, h);
  				}
  				else {
  					detail::protected_handler<false, handler_t> h(error_handler);
  					base_t::push();
  					int pushcount = stack::multi_push_reference(lua_state(), std::forward<Args>(args)...);
  					return invoke(types<Ret...>(), std::make_index_sequence<sizeof...(Ret)>(), pushcount, h);
  				}
  			}
  			else {
  				// the function is already on the stack at the right location
  				if (error_handler.valid()) {
  					// the handler will be pushed onto the stack manually,
  					// since it's not already on the stack this means we need to push our own
  					// function on the stack too and swap things to be in-place
  					if constexpr (!is_stack_handler::value) {
  						// so, we need to remove the function at the top and then dump the handler out ourselves
  						base_t::push();
  					}
  					detail::protected_handler<true, handler_t> h(error_handler);
  					if constexpr (!is_stack_handler::value) {
  						lua_replace(lua_state(), -3);
  						h.stackindex = lua_absindex(lua_state(), -2);
  					}
  					int pushcount = stack::multi_push_reference(lua_state(), std::forward<Args>(args)...);
  					return invoke(types<Ret...>(), std::make_index_sequence<sizeof...(Ret)>(), pushcount, h);
  				}
  				else {
  					detail::protected_handler<false, handler_t> h(error_handler);
  					int pushcount = stack::multi_push_reference(lua_state(), std::forward<Args>(args)...);
  					return invoke(types<Ret...>(), std::make_index_sequence<sizeof...(Ret)>(), pushcount, h);
  				}
  			}
  		}
  	};
  } // namespace sol
  
  #endif // SOL_FUNCTION_HPP
  