sol2/include/sol/coroutine.hpp

// sol2

// The MIT License (MIT)

// Copyright (c) 2013-2021 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:

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// 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_COROUTINE_HPP
#define SOL_COROUTINE_HPP

#include <sol/reference.hpp>
#include <sol/object.hpp>
#include <sol/stack.hpp>
#include <sol/function_result.hpp>
#include <sol/thread.hpp>
#include <sol/protected_handler.hpp>

namespace sol {
	template <typename Reference>
	class basic_coroutine : public basic_object<Reference> {
	private:
		using base_t = basic_object<Reference>;
		using handler_t = reference;

	private:
		call_status stats = call_status::yielded;

		void luacall(std::ptrdiff_t argcount, std::ptrdiff_t) {
#if SOL_LUA_VERSION_I_ >= 504
			int nresults;
			stats = static_cast<call_status>(lua_resume(lua_state(), nullptr, static_cast<int>(argcount), &nresults));
#else
			stats = static_cast<call_status>(lua_resume(lua_state(), nullptr, static_cast<int>(argcount)));
#endif
		}

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

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

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

		protected_function_result invoke(types<>, std::index_sequence<>, std::ptrdiff_t n) {
			int firstreturn = 1;
			luacall(n, LUA_MULTRET);
			int poststacksize = lua_gettop(this->lua_state());
			int returncount = poststacksize - (firstreturn - 1);
			if (error()) {
				if (m_error_handler.valid()) {
					string_view err = stack::get<string_view>(this->lua_state(), poststacksize);
					m_error_handler.push();
					stack::push(this->lua_state(), err);
					lua_call(lua_state(), 1, 1);
				}
				return protected_function_result(this->lua_state(), lua_absindex(this->lua_state(), -1), 1, returncount, status());
			}
			return protected_function_result(this->lua_state(), firstreturn, returncount, returncount, status());
		}

	public:
		using base_t::lua_state;

		basic_coroutine() = default;
		template <typename T,
		     meta::enable<meta::neg<std::is_same<meta::unqualified_t<T>, basic_coroutine>>,
		          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_coroutine(T&& r) noexcept
		: base_t(std::forward<T>(r)), m_error_handler(detail::get_default_handler<reference, is_main_threaded<base_t>::value>(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_coroutine>(lua_state(), -1, handler);
			}
#endif // Safety
		}

		basic_coroutine(const basic_coroutine& other) = default;
		basic_coroutine& operator=(const basic_coroutine&) = default;

		basic_coroutine(basic_coroutine&& other) noexcept : base_t(std::move(other)), m_error_handler(this->lua_state(), std::move(other.m_error_handler)) {
		}

		basic_coroutine& operator=(basic_coroutine&& other) noexcept {
			base_t::operator=(std::move(other));
			// must change the state, since it could change on the coroutine type
			m_error_handler = handler_t(this->lua_state(), std::move(other.m_error_handler));
			return *this;
		}

		basic_coroutine(const basic_function<base_t>& b) noexcept
		: basic_coroutine(b, detail::get_default_handler<reference, is_main_threaded<base_t>::value>(b.lua_state())) {
		}
		basic_coroutine(basic_function<base_t>&& b) noexcept
		: basic_coroutine(std::move(b), detail::get_default_handler<reference, is_main_threaded<base_t>::value>(b.lua_state())) {
		}
		basic_coroutine(const basic_function<base_t>& b, handler_t eh) noexcept : base_t(b), m_error_handler(std::move(eh)) {
		}
		basic_coroutine(basic_function<base_t>&& b, handler_t eh) noexcept : base_t(std::move(b)), m_error_handler(std::move(eh)) {
		}
		basic_coroutine(const stack_reference& r) noexcept
		: basic_coroutine(r.lua_state(), r.stack_index(), detail::get_default_handler<reference, is_main_threaded<base_t>::value>(r.lua_state())) {
		}
		basic_coroutine(stack_reference&& r) noexcept
		: basic_coroutine(r.lua_state(), r.stack_index(), detail::get_default_handler<reference, is_main_threaded<base_t>::value>(r.lua_state())) {
		}
		basic_coroutine(const stack_reference& r, handler_t eh) noexcept : basic_coroutine(r.lua_state(), r.stack_index(), std::move(eh)) {
		}
		basic_coroutine(stack_reference&& r, handler_t eh) noexcept : basic_coroutine(r.lua_state(), r.stack_index(), std::move(eh)) {
		}

		template <typename Super>
		basic_coroutine(const proxy_base<Super>& p)
		: basic_coroutine(p, detail::get_default_handler<reference, is_main_threaded<base_t>::value>(p.lua_state())) {
		}
		template <typename Super>
		basic_coroutine(proxy_base<Super>&& p)
		: basic_coroutine(std::move(p), detail::get_default_handler<reference, is_main_threaded<base_t>::value>(p.lua_state())) {
		}
		template <typename Proxy, typename HandlerReference,
		     meta::enable<std::is_base_of<proxy_base_tag, meta::unqualified_t<Proxy>>,
		          meta::neg<is_lua_index<meta::unqualified_t<HandlerReference>>>> = meta::enabler>
		basic_coroutine(Proxy&& p, HandlerReference&& eh) : basic_coroutine(detail::force_cast<base_t>(p), std::forward<HandlerReference>(eh)) {
		}

		template <typename T, meta::enable<is_lua_reference<meta::unqualified_t<T>>> = meta::enabler>
		basic_coroutine(lua_State* L, T&& r) noexcept
		: basic_coroutine(L, std::forward<T>(r), detail::get_default_handler<reference, is_main_threaded<base_t>::value>(L)) {
		}
		template <typename T, meta::enable<is_lua_reference<meta::unqualified_t<T>>> = meta::enabler>
		basic_coroutine(lua_State* L, T&& r, handler_t eh) : base_t(L, std::forward<T>(r)), m_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_coroutine>(lua_state(), -1, handler);
#endif // Safety
		}

		basic_coroutine(lua_nil_t n) : base_t(n), m_error_handler(n) {
		}

		basic_coroutine(lua_State* L, int index = -1)
		: basic_coroutine(L, index, detail::get_default_handler<reference, is_main_threaded<base_t>::value>(L)) {
		}
		basic_coroutine(lua_State* L, int index, handler_t eh) : base_t(L, index), m_error_handler(std::move(eh)) {
#ifdef SOL_SAFE_REFERENCES
			constructor_handler handler {};
			stack::check<basic_coroutine>(L, index, handler);
#endif // Safety
		}
		basic_coroutine(lua_State* L, absolute_index index)
		: basic_coroutine(L, index, detail::get_default_handler<reference, is_main_threaded<base_t>::value>(L)) {
		}
		basic_coroutine(lua_State* L, absolute_index index, handler_t eh) : base_t(L, index), m_error_handler(std::move(eh)) {
#if SOL_IS_ON(SOL_SAFE_REFERENCES_I_)
			constructor_handler handler {};
			stack::check<basic_coroutine>(L, index, handler);
#endif // Safety
		}
		basic_coroutine(lua_State* L, raw_index index)
		: basic_coroutine(L, index, detail::get_default_handler<reference, is_main_threaded<base_t>::value>(L)) {
		}
		basic_coroutine(lua_State* L, raw_index index, handler_t eh) : base_t(L, index), m_error_handler(std::move(eh)) {
#if SOL_IS_ON(SOL_SAFE_REFERENCES_I_)
			constructor_handler handler {};
			stack::check<basic_coroutine>(L, index, handler);
#endif // Safety
		}
		basic_coroutine(lua_State* L, ref_index index)
		: basic_coroutine(L, index, detail::get_default_handler<reference, is_main_threaded<base_t>::value>(L)) {
		}
		basic_coroutine(lua_State* L, ref_index index, handler_t eh) : base_t(L, index), m_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_coroutine>(lua_state(), -1, handler);
#endif // Safety
		}

		call_status status() const noexcept {
			return stats;
		}

		bool error() const noexcept {
			call_status cs = status();
			return cs != call_status::ok && cs != call_status::yielded;
		}

		bool runnable() const noexcept {
			return base_t::valid() && (status() == call_status::yielded);
		}

		explicit operator bool() const noexcept {
			return runnable();
		}

		template <typename... Args>
		protected_function_result operator()(Args&&... args) {
			return call<>(std::forward<Args>(args)...);
		}

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

		template <typename... Ret, typename... Args>
		decltype(auto) call(Args&&... args) {
			// some users screw up coroutine.create
			// and try to use it with sol::coroutine without ever calling the first resume in Lua
			// this makes the stack incompatible with other kinds of stacks: protect against this
			// make sure coroutines don't screw us over
			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);
		}

	private:
		handler_t m_error_handler;
	};
} // namespace sol

#endif // SOL_COUROUTINE_HPP