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| ** |
| ** Copyright (C) 2016 The Qt Company Ltd. |
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| ** This file is part of the QtXmlPatterns module of the Qt Toolkit. |
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| ** GNU General Public License Usage |
| ** Alternatively, this file may be used under the terms of the GNU |
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| ** Public license version 3 or any later version approved by the KDE Free |
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| |
| // |
| // W A R N I N G |
| // ------------- |
| // |
| // This file is not part of the Qt API. It exists purely as an |
| // implementation detail. This header file may change from version to |
| // version without notice, or even be removed. |
| // |
| // We mean it. |
| |
| #ifndef Patternist_SingletonIterator_H |
| #define Patternist_SingletonIterator_H |
| |
| #include <QtXmlPatterns/private/qabstractxmlforwarditerator_p.h> |
| |
| #include <QtXmlPatterns/private/qprimitives_p.h> |
| |
| QT_BEGIN_NAMESPACE |
| |
| namespace QPatternist |
| { |
| /** |
| * @short An QAbstractXmlForwardIterator over exactly one item. |
| * |
| * SingletonIterator's constructor takes one value which is |
| * the item it forms an QAbstractXmlForwardIterator over. Other QAbstractXmlForwardIterator instances can |
| * also form an QAbstractXmlForwardIterator with one in length, but by that SingletonIterator |
| * has this as it only task, it means it is efficient at it. |
| * |
| * Having to represent single items in Iterators is relatively common. |
| * |
| * @author Frans Englich <frans.englich@nokia.com> |
| * @ingroup Patternist_iterators |
| */ |
| template<typename T> |
| class SingletonIterator : public QAbstractXmlForwardIterator<T> |
| { |
| public: |
| /** |
| * Creates an iterator over @p item. |
| * |
| * @note item may not be @c null. Use the EmptyIterator for |
| * the empty sequence |
| */ |
| SingletonIterator(const T &item) : m_item(item), |
| m_position(0) |
| { |
| Q_ASSERT(!qIsForwardIteratorEnd(item)); |
| } |
| |
| virtual T next() |
| { |
| switch(m_position) |
| { |
| case 0: |
| { |
| ++m_position; |
| return m_item; |
| } |
| case 1: |
| { |
| m_position = -1; |
| return T(); |
| } |
| default: |
| { |
| Q_ASSERT(m_position == -1); |
| return T(); |
| } |
| } |
| } |
| |
| virtual T current() const |
| { |
| if(m_position == 1) |
| return m_item; |
| else |
| return T(); |
| } |
| |
| virtual xsInteger position() const |
| { |
| return m_position; |
| } |
| |
| /** |
| * @returns a copy of this instance, rewinded to the beginning. |
| */ |
| virtual typename QAbstractXmlForwardIterator<T>::Ptr toReversed() |
| { |
| return typename QAbstractXmlForwardIterator<T>::Ptr(new SingletonIterator<T>(m_item)); |
| } |
| |
| /** |
| * @returns always 1 |
| */ |
| virtual xsInteger count() |
| { |
| return 1; |
| } |
| |
| virtual typename QAbstractXmlForwardIterator<T>::Ptr copy() const |
| { |
| return typename QAbstractXmlForwardIterator<T>::Ptr(new SingletonIterator(m_item)); |
| } |
| |
| private: |
| const T m_item; |
| qint8 m_position; |
| }; |
| |
| /** |
| * @short An object generator for SingletonIterator. |
| * |
| * makeSingletonIterator() is a convenience function for avoiding specifying |
| * the full template instantiation for SingletonIterator. Conceptually, it |
| * is identical to Qt's qMakePair(). |
| * |
| * @relates SingletonIterator |
| */ |
| template<typename T> |
| inline |
| typename SingletonIterator<T>::Ptr |
| makeSingletonIterator(const T &item) |
| { |
| return typename SingletonIterator<T>::Ptr(new SingletonIterator<T>(item)); |
| } |
| } |
| |
| QT_END_NAMESPACE |
| |
| #endif |