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engines/titanic/support/fixed_queue.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 TITANIC_FIXED_QUEUE_H
+#define TITANIC_FIXED_QUEUE_H
+
+#include "common/scummsys.h"
+#include "common/array.h"
+
+namespace Titanic {
+
+/**
+ * Extremely simple fixed size queue class.
+ */
+template<class T, uint MAX_SIZE = 10>
+class FixedQueue {
+	typedef uint size_type;
+protected:
+	Common::Array<T> _data;
+	size_type _topIndex;
+public:
+	FixedQueue() : _topIndex(0) {
+		_data.reserve(MAX_SIZE);
+	}
+
+	/**
+	 * Returns the size of the queue in use
+	 */
+	size_type size() const { return _data.size() - _topIndex; }
+
+	/**
+	 * Returns the amount of free remaining space in the queue
+	 */
+	size_type freeSize() const { return MAX_SIZE - size(); }
+
+	/**
+	 * Returns true if the queue is empty
+	 */
+	bool empty() const {
+		return size() == 0;
+	}
+
+	/**
+	 * Returns true if the queue is full
+	 */
+	bool full() const {
+		return freeSize() == 0;
+	}
+
+	/**
+	 * Clears the queue
+	 */
+	void clear() {
+		_data.clear();
+		_topIndex = 0;
+	}
+
+	/**
+	 * If the tail of the queue in use has reached the end of the internal
+	 * array, pushes all pending data back to the start of the array
+	 */
+	void compact() {
+		if (_data.size() == MAX_SIZE && _topIndex > 0) {
+			if (_topIndex < MAX_SIZE)
+				Common::copy(&_data[_topIndex], &_data[0] + MAX_SIZE, &_data[0]);
+			_data.resize(size());
+			_topIndex = 0;
+		}
+	}
+
+	/**
+	 * Adds a value to the end of the queue
+	 */
+	void push(const T &v) {
+		assert(size() < MAX_SIZE);
+		compact();
+		_data.push_back(v);
+	}
+
+	/**
+	 * Returns the top value on the queue
+	 */
+	const T &top() const {
+		assert(size() > 0);
+		return _data[_topIndex];
+	}
+
+	/**
+	 * Returns the top value on the queue
+	 */
+	T &top() {
+		assert(size() > 0);
+		return _data[_topIndex];
+	}
+
+	/**
+	 * Pops the top value off the queue
+	 */
+	T pop() {
+		T tmp = top();
+		++_topIndex;
+		return tmp;
+	}
+
+	/**
+	 * Returns values from within the queue without popping them
+	 */
+	T &operator[](size_type i) {
+		assert(i < size());
+		return _data[_topIndex + i];
+	}
+
+	/**
+	 * Returns values from within the queue without popping them
+	 */
+	const T &operator[](size_type i) const {
+		assert(i < size());
+		return _data[_topIndex + i];
+	}
+};
+
+} // End of namespace Titanic
+
+#endif