sol2/include/sol/inheritance.hpp

// sol2

// The MIT License (MIT)

// Copyright (c) 2013-2018 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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// CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

#ifndef SOL_INHERITANCE_HPP
#define SOL_INHERITANCE_HPP

#include "types.hpp"
#include "usertype_traits.hpp"

namespace sol {
	template <typename... Args>
	struct base_list {};
	template <typename... Args>
	using bases = base_list<Args...>;

	typedef bases<> base_classes_tag;
	const auto base_classes = base_classes_tag();

	namespace detail {

		inline decltype(auto) base_class_check_key() {
			static const auto& key = "class_check";
			return key;
		}

		inline decltype(auto) base_class_cast_key() {
			static const auto& key = "class_cast";
			return key;
		}

		inline decltype(auto) base_class_index_propogation_key() {
			static const auto& key = u8"\xF0\x9F\x8C\xB2.index";
			return key;
		}

		inline decltype(auto) base_class_new_index_propogation_key() {
			static const auto& key = u8"\xF0\x9F\x8C\xB2.new_index";
			return key;
		}

		template <typename T>
		struct inheritance {
			typedef typename base<T>::type bases_t;

			static bool type_check_bases(types<>, const string_view&) {
				return false;
			}

			template <typename Base, typename... Args>
			static bool type_check_bases(types<Base, Args...>, const string_view& ti) {
				return ti == usertype_traits<Base>::qualified_name() || type_check_bases(types<Args...>(), ti);
			}

			static bool type_check(const string_view& ti) {
				return ti == usertype_traits<T>::qualified_name() || type_check_bases(bases_t(), ti);
			}

			static void* type_cast_bases(types<>, T*, const string_view&) {
				return nullptr;
			}

			template <typename Base, typename... Args>
			static void* type_cast_bases(types<Base, Args...>, T* data, const string_view& ti) {
				// Make sure to convert to T first, and then dynamic cast to the proper type
				return ti != usertype_traits<Base>::qualified_name() ? type_cast_bases(types<Args...>(), data, ti) : static_cast<void*>(static_cast<Base*>(data));
			}

			static void* type_cast(void* voiddata, const string_view& ti) {
				T* data = static_cast<T*>(voiddata);
				return static_cast<void*>(ti != usertype_traits<T>::qualified_name() ? type_cast_bases(bases_t(), data, ti) : data);
			}

			template <typename U>
			static bool type_unique_cast_bases(types<>, void*, void*, const string_view&) {
				return 0;
			}

			template <typename U, typename Base, typename... Args>
			static int type_unique_cast_bases(types<Base, Args...>, void* source_data, void* target_data, const string_view& ti) {
				typedef unique_usertype_traits<U> uu_traits;
				typedef typename uu_traits::template rebind_base<Base> base_ptr;
				string_view base_ti = usertype_traits<Base>::qualified_name();
				if (base_ti == ti) {
					if (target_data != nullptr) {
						U* source = static_cast<U*>(source_data);
						base_ptr* target = static_cast<base_ptr*>(target_data);
						// perform proper derived -> base conversion
						*target = *source;
					}
					return 2;
				}
				return type_unique_cast_bases<U>(types<Args...>(), source_data, target_data, ti);
			}

			template <typename U>
			static int type_unique_cast(void* source_data, void* target_data, const string_view& ti, const string_view& rebind_ti) {
				typedef unique_usertype_traits<U> uu_traits;
				typedef typename uu_traits::template rebind_base<void> rebind_t;
				typedef std::conditional_t<std::is_void<rebind_t>::value, types<>, bases_t> cond_bases_t;
				string_view this_rebind_ti = usertype_traits<rebind_t>::qualified_name();
				if (rebind_ti != this_rebind_ti) {
					// this is not even of the same unique type
					return 0;
				}
				string_view this_ti = usertype_traits<T>::qualified_name();
				if (ti == this_ti) {
					// direct match, return 1
					return 1;
				}
				return type_unique_cast_bases<U>(cond_bases_t(), source_data, target_data, ti);
			}
		};

		using inheritance_check_function = decltype(&inheritance<void>::type_check);
		using inheritance_cast_function = decltype(&inheritance<void>::type_cast);
		using inheritance_unique_cast_function = decltype(&inheritance<void>::type_unique_cast<void>);
	} // namespace detail
} // namespace sol

#define SOL_BASE_CLASSES(T, ...) \
	template <>                 \
	struct ::sol::base<T> : ::std::true_type { typedef ::sol::types<__VA_ARGS__> type; };
#define SOL_DERIVED_CLASSES(T, ...) \
	template <>                    \
	struct ::sol::derive<T> : ::std::true_type { typedef ::sol::types<__VA_ARGS__> type; };

#endif // SOL_INHERITANCE_HPP