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common/stablemap.h

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+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#ifndef COMMON_STABLEMAP_H
+#define COMMON_STABLEMAP_H
+
+#include "common/rb_tree.h"
+
+namespace Common {
+
+/**
+ * @defgroup common_stablemap stable map
+ * @ingroup common
+ *
+ * @brief API for operating on a key value map
+ *
+ * @{
+ */
+
+/**
+ * Ordered associative container meant as a drop-in replacement
+ * for the C++ standard library's std::map.
+ */
+template<class Key, class Val, class CompFunc = Common::Less<Key> >
+class StableMap {
+	using TreeT = RBTree<Pair<Key, Val>, Key, PairFirst<Key, Val>, CompFunc>;
+
+public:
+	using value_type = Pair<Key, Val>;                    /*!< Type of the value obtained by dereferencing a StableMap iterator. */
+	using iterator = typename TreeT::BasicIterator;       /*!< StableMap iterator. */
+	using const_iterator = typename TreeT::ConstIterator; /*!< Const-qualified StableMap iterator. */
+
+	/** Clears the contents of the map */
+	void clear() {
+		_items.clear();
+	}
+
+	/** Return an iterator pointing to the first element in the map. */
+	iterator begin() {
+		return _items.begin();
+	}
+
+	/** Return an iterator pointing to the last element in the map. */
+	iterator end() {
+		return _items.end();
+	}
+
+	/** Return a const iterator pointing to the first element in the map. */
+	const_iterator begin() const {
+		return _items.begin();
+	}
+
+	/** Return a const iterator pointing to the last element in the map. */
+	const_iterator end() const {
+		return _items.end();
+	}
+
+	/**
+	 * Returns an iterator to the first item thas is not less than @p key
+	 * in the map (or end() if this cannot be found).
+	 */
+	const_iterator lower_bound(const Key &key) const {
+		return _items.lowerBound(key);
+	}
+
+	/**
+	 * Returns a const iterator to the first item thas is not less than @p key
+	 * in the map (or end() if this cannot be found).
+	 */
+	iterator lower_bound(const Key &key) {
+		return _items.lowerBound(key);
+	}
+
+	/**
+	 * Returns an iterator to the first item bigger than @p key
+	 * in the map (or end() if this cannot be found).
+	 */
+	iterator upper_bound(const Key &key) {
+		return _items.upperBound(key);
+	}
+
+	/**
+	 * Returns an iterator to the item with the given key,
+	 * or end() if the item was not found.
+	 */
+	iterator find(const Key &theKey) {
+		iterator it = _items.lowerBound(theKey);
+		if (it != this->end() && compareEqual(it->first, theKey))
+			return it;
+		return this->end();
+	}
+
+	/**
+	 * Returns a const iterator to the item with the given key,
+	 * or end() if the item was not found.
+	 */
+	const_iterator find(const Key &theKey) const {
+		const_iterator it = _items.lowerBound(theKey);
+		if (it != this->end() && compareEqual(it->first, theKey))
+			return it;
+		return this->end();
+	}
+
+	/**
+	 * Square brackets operator accesses items by key, creating if necessary
+	 */
+	Val &operator[](const Key &theKey) {
+		iterator it = _items.lowerBound(theKey);
+		if (it == this->end() || !compareEqual(it->first, theKey)) {
+			iterator i = _items.insert(value_type(theKey, Val()));
+			return i->second;
+		}
+		return it->second;
+	}
+
+	/** Erases the item in the map pointed by @p it .*/
+	iterator erase(iterator it) {
+		return _items.erase(it);
+	}
+
+	/**
+	 * Erase the elements from @p first to @p last and return an iterator pointing to the next element in the map.
+	 * @note
+	 * If [first, last) is not a valid range for the map, the behaviour is undefined.
+	 */
+	iterator erase(iterator first, iterator last) {
+		return _items.erase(first, last);
+	}
+
+	/**
+	 * Erases the item with the given key.
+	 * Returns the number of elements removed (0 or 1)
+	 */
+	size_t erase(const Key &theKey) {
+		iterator it = find(theKey);
+		if (it != this->end()) {
+			erase(it);
+			return 1;
+		}
+		return 0;
+	}
+
+	/**
+	 * Tries to insert the value @p val in the map. If the value is inserted,
+	 * the pair (it, true), where it is the iterator to the inserted value,
+	 * is returned, otherwise (lower_bound(val), false) is returned
+	 */
+	Pair<iterator, bool> insert(const value_type &val) {
+		iterator it = _items.lowerBound(val.first);
+		if (it == this->end() || !compareEqual(it->first, val.first))
+			return {_items.insert(val), true};
+		return {it, false};
+	}
+
+	/** Returns the size of the map. */
+	size_t size() const {
+		return _items.size();
+	}
+
+	/**
+	 * Returns true if the map is empty.
+	 * Shorthand for:
+	 * @code
+	 * map.size() == 0
+	 * @endcode
+	 */
+	bool empty() const {
+		return _items.isEmpty();
+	}
+
+	/**
+	 * Returns the number of elements with a matching key
+	 */
+	size_t count(const Key &key) {
+		int count_ = 0;
+		for (iterator it = this->begin(); it != this->end(); ++it) {
+			if (compareEqual(it->first, key))
+				++count_;
+		}
+		return count_;
+	}
+
+private:
+	bool compareEqual(const Key &a, const Key &b) const {
+		return !_comp(a, b) && !_comp(b, a);
+	}
+
+	TreeT _items;
+	CompFunc _comp;
+};
+
+/** @} */
+
+} // End of namespace Common
+
+#endif