Added a priority queue
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Jordan Sherer
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253
qpriorityqueue.h
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253
qpriorityqueue.h
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/****************************************************************************
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**
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** Copyright (C) 2015 Corentin Chary <corentin.chary@gmail.cm>
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**
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** This file could be part of the QtCore module of the Qt Toolkit.
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**
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** $QT_BEGIN_LICENSE:LGPL$
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** No Commercial Usage
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** This file contains pre-release code and may not be distributed.
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** You may use this file in accordance with the terms and conditions
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** contained in the Technology Preview License Agreement accompanying
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** this package.
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**
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** GNU Lesser General Public License Usage
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** Alternatively, this file may be used under the terms of the GNU Lesser
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** General Public License version 2.1 as published by the Free Software
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** Foundation and appearing in the file LICENSE.LGPL included in the
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** packaging of this file. Please review the following information to
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** ensure the GNU Lesser General Public License version 2.1 requirements
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** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
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**
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** In addition, as a special exception, Nokia gives you certain additional
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** rights. These rights are described in the Nokia Qt LGPL Exception
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** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
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**
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** If you have questions regarding the use of this file, please contact
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** Nokia at qt-info@nokia.com.
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**
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**
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**
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**
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**
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**
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**
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**
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** $QT_END_LICENSE$
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**
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****************************************************************************/
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#ifndef QPRIORITY_QUEUE_H
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#define QPRIORITY_QUEUE_H
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#include <QtCore/qalgorithms.h>
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QT_BEGIN_HEADER
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QT_BEGIN_NAMESPACE
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QT_MODULE(Core)
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template <class T> class QList;
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#ifndef QT_NO_STL
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#include <queue>
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#include <vector>
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#else
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/* Fallback class used when stl is not available */
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template <class T, typename LessThan = qLess < T > >
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class QPriorityQueuePrivate {
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public:
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inline QPriorityQueuePrivate(LessThan l) : lessThan(l), d() {}
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inline ~QPriorityQueuePrivate() {}
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inline void clear() { return d.clear(); }
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inline int size() const { return d.size(); }
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inline bool empty() const { return d.empty(); }
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inline T &top() { return d.front(); }
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void pop();
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void push(const T &value);
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private:
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inline int parent(int i) {
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return (i - 1) / 2;
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}
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inline int leftChild(int i) {
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return 2 * i + 1;
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}
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inline int rightChild(int i) {
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return 2 * i + 2;
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}
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LessThan lessThan;
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QList < T > d;
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};
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#endif
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template <class T, typename LessThan = qLess < T > >
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class Q_CORE_EXPORT QPriorityQueue
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{
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public:
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inline QPriorityQueue(LessThan l = qLess < T >())
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: lessThan(l), d(lessThan) { }
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inline QPriorityQueue(const QPriorityQueue<T> &q)
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: lessThan(q.lessThan), d(q.d) { }
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inline ~QPriorityQueue() { }
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QPriorityQueue<T> &operator=(const QPriorityQueue<T> &q) {
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d = q.d; return *this;
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}
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inline int size() const { return d.size(); }
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inline bool isEmpty() const { return empty(); }
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// like qlist
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void clear();
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void append(const T &t) { return enqueue(t); }
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void append(const QList<T> &t);
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T takeFirst() { return dequeue(); }
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inline int length() const { return size(); } // Same as count()
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inline T& first() { return head(); }
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inline const T& first() const { return head(); }
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inline void removeFirst() { pop(); }
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inline bool startsWith(const T &t) const
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{ return !isEmpty() && first() == t; }
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// like qqueue
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inline void enqueue(const T &t) { push(t); }
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inline T dequeue() { T t = d.top(); d.pop(); return t; }
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inline T &head() { top(); }
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inline const T &head() const { top(); }
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// stl compatibility
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typedef int size_type;
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typedef T value_type;
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inline bool empty() const { return d.empty(); }
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inline const value_type& top() { Q_ASSERT(!isEmpty()); return d.top(); }
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inline void push(const value_type& x) { return d.push(x); }
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inline void pop() { Q_ASSERT(!isEmpty()); d.pop(); }
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// comfort
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inline QPriorityQueue<T> &operator+=(const T &t) {
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enqueue(t); return *this;
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}
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inline QPriorityQueue<T> &operator<< (const T &t) {
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enqueue(t); return *this;
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}
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inline QPriorityQueue<T> &operator>> (T &t) {
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t = d.top(); d.pop(); return *this;
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}
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#ifndef QT_NO_STL
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static inline QPriorityQueue<T>fromStdPriorityQueue(
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const std::priority_queue<T> &q) {
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QPriorityQueue<T> tmp; tmp.d = q; return tmp;
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}
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inline std::priority_queue<T> toStdPriorityQueue() const {
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return d;
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}
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#endif
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private:
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LessThan lessThan;
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#ifndef QT_NO_STL
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std::priority_queue <T, std::vector < T >, LessThan> d;
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#else
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QPriorityQueuePrivate <T> d;
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#endif
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};
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#ifndef QT_NO_STL
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template <typename T, typename LessThan>
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Q_INLINE_TEMPLATE void QPriorityQueue<T, LessThan>::clear()
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{
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d = std::priority_queue<T>(lessThan);
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}
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#else
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template <typename T, typename LessThan>
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Q_INLINE_TEMPLATE void QPriorityQueue<T, LessThan>::clear()
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{
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d.clear();
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}
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#endif
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template <typename T, typename LessThan>
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Q_OUTOFLINE_TEMPLATE void QPriorityQueue<T, LessThan>::append(const QList<T> &t)
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{
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foreach (T & e, t)
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push(e);
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}
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// Re-implement std::priority_queue if STL not available, probably
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// less efficient.
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#ifdef QT_NO_STL
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/*!
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* Pop an element from the queue and reorder it using an
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* inlined binary heap.
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*
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* \internal
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*/
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template <typename T, typename LessThan>
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Q_OUTOFLINE_TEMPLATE void QPriorityQueuePrivate<T, LessThan>::pop()
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{
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int i = 0;
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ssize_t size = d.size();;
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if(!size)
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return;
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if(size == 1)
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return d.clear();
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d[0] = d.takeLast();
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while(i < size - 1) {
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int left = leftChild(i);
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int right = rightChild(i);
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bool validLeft = left < size;
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bool validRight = right < size;
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if(validLeft && lessThan(d.at(i), d.at(left)))
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if(validRight && !lessThan(d.at(right), d.at(left))) {
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d.swap(i, right);
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i = right;
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} else {
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d.swap(i, left);
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i = left;
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}
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else if(validRight && lessThan(d.at(i), d.at(right))) {
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d.swap(i, right);
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i = right;
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}
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else
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break;
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}
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}
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/*!
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* Push an element with a given priority to the right place.
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*
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* \internal
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*/
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template <typename T, typename LessThan>
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Q_OUTOFLINE_TEMPLATE void QPriorityQueuePrivate<T, LessThan>::push(const T &value)
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{
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int i = d.size();
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d.append(value);
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while(i != 0 && !lessThan(d.at(i), d.at(parent(i)))) {
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d.swap(i, parent(i));
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i = parent(i);
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}
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}
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#endif
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QT_END_NAMESPACE
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QT_END_HEADER
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#endif // QPRIORITY_QUEUE_H
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