initial commit, 4.5 stable

core/templates/lru.h

@@ -0,0 +1,150 @@
+/**************************************************************************/
+/*  lru.h                                                                 */
+/**************************************************************************/
+/*                         This file is part of:                          */
+/*                             GODOT ENGINE                               */
+/*                        https://godotengine.org                         */
+/**************************************************************************/
+/* Copyright (c) 2014-present Godot Engine contributors (see AUTHORS.md). */
+/* Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur.                  */
+/*                                                                        */
+/* 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.                 */
+/**************************************************************************/
+
+#pragma once
+
+#include "hash_map.h"
+#include "list.h"
+
+template <typename TKey, typename TData, typename Hasher = HashMapHasherDefault, typename Comparator = HashMapComparatorDefault<TKey>, void (*BeforeEvict)(TKey &, TData &) = nullptr>
+class LRUCache {
+public:
+	struct Pair {
+		TKey key;
+		TData data;
+
+		Pair() {}
+		Pair(const TKey &p_key, const TData &p_data) :
+				key(p_key),
+				data(p_data) {
+		}
+	};
+
+	typedef typename List<Pair>::Element *Element;
+
+private:
+	List<Pair> _list;
+	HashMap<TKey, Element, Hasher, Comparator> _map;
+	size_t capacity;
+
+public:
+	const Pair *insert(const TKey &p_key, const TData &p_value) {
+		Element *e = _map.getptr(p_key);
+		Element n = _list.push_front(Pair(p_key, p_value));
+
+		if (e) {
+			GODOT_GCC_WARNING_PUSH_AND_IGNORE("-Waddress")
+			if constexpr (BeforeEvict != nullptr) {
+				BeforeEvict((*e)->get().key, (*e)->get().data);
+			}
+			GODOT_GCC_WARNING_POP
+			_list.erase(*e);
+			_map.erase(p_key);
+		}
+		_map[p_key] = _list.front();
+
+		while (_map.size() > capacity) {
+			Element d = _list.back();
+			GODOT_GCC_WARNING_PUSH_AND_IGNORE("-Waddress")
+			if constexpr (BeforeEvict != nullptr) {
+				BeforeEvict(d->get().key, d->get().data);
+			}
+			GODOT_GCC_WARNING_POP
+			_map.erase(d->get().key);
+			_list.pop_back();
+		}
+
+		return &n->get();
+	}
+
+	void clear() {
+		_map.clear();
+		_list.clear();
+	}
+
+	bool has(const TKey &p_key) const {
+		return _map.getptr(p_key);
+	}
+
+	bool erase(const TKey &p_key) {
+		Element *e = _map.getptr(p_key);
+		if (!e) {
+			return false;
+		}
+		_list.move_to_front(*e);
+		_map.erase(p_key);
+		_list.pop_front();
+		return true;
+	}
+
+	const TData &get(const TKey &p_key) {
+		Element *e = _map.getptr(p_key);
+		CRASH_COND(!e);
+		_list.move_to_front(*e);
+		return (*e)->get().data;
+	}
+
+	const TData *getptr(const TKey &p_key) {
+		Element *e = _map.getptr(p_key);
+		if (!e) {
+			return nullptr;
+		} else {
+			_list.move_to_front(*e);
+			return &(*e)->get().data;
+		}
+	}
+
+	_FORCE_INLINE_ size_t get_capacity() const { return capacity; }
+	_FORCE_INLINE_ size_t get_size() const { return _map.size(); }
+
+	void set_capacity(size_t p_capacity) {
+		if (capacity > 0) {
+			capacity = p_capacity;
+			while (_map.size() > capacity) {
+				Element d = _list.back();
+				GODOT_GCC_WARNING_PUSH_AND_IGNORE("-Waddress")
+				if constexpr (BeforeEvict != nullptr) {
+					BeforeEvict(d->get().key, d->get().data);
+				}
+				GODOT_GCC_WARNING_POP
+				_map.erase(d->get().key);
+				_list.pop_back();
+			}
+		}
+	}
+
+	LRUCache() {
+		capacity = 64;
+	}
+
+	LRUCache(int p_capacity) {
+		capacity = p_capacity;
+	}
+};