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Diffstat (limited to 'src/xmlpatterns/iterators/qitemmappingiterator_p.h')
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diff --git a/src/xmlpatterns/iterators/qitemmappingiterator_p.h b/src/xmlpatterns/iterators/qitemmappingiterator_p.h new file mode 100644 index 0000000..2aada7b --- /dev/null +++ b/src/xmlpatterns/iterators/qitemmappingiterator_p.h @@ -0,0 +1,190 @@ +/**************************************************************************** +** +** Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies). +** All rights reserved. +** Contact: Nokia Corporation (qt-info@nokia.com) +** +** This file is part of the QtXmlPatterns module of the Qt Toolkit. +** +** $QT_BEGIN_LICENSE:LGPL$ +** No Commercial Usage +** This file contains pre-release code and may not be distributed. +** You may use this file in accordance with the terms and conditions +** contained in the Technology Preview License Agreement accompanying +** this package. +** +** GNU Lesser General Public License Usage +** Alternatively, this file may be used under the terms of the GNU Lesser +** General Public License version 2.1 as published by the Free Software +** Foundation and appearing in the file LICENSE.LGPL included in the +** packaging of this file. Please review the following information to +** ensure the GNU Lesser General Public License version 2.1 requirements +** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html. +** +** In addition, as a special exception, Nokia gives you certain additional +** rights. These rights are described in the Nokia Qt LGPL Exception +** version 1.1, included in the file LGPL_EXCEPTION.txt in this package. +** +** If you have questions regarding the use of this file, please contact +** Nokia at qt-info@nokia.com. +** +** +** +** +** +** +** +** +** $QT_END_LICENSE$ +** +****************************************************************************/ + +// +// 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_ItemMappingIterator_H +#define Patternist_ItemMappingIterator_H + +#include "qabstractxmlforwarditerator_p.h" +#include "qdynamiccontext_p.h" + +QT_BEGIN_HEADER + +QT_BEGIN_NAMESPACE + +namespace QPatternist +{ + /** + * @short Proxies another QAbstractXmlForwardIterator, and for each item, returns the + * Item returned from a mapping function. + * + * ItemMappingIterator is practical when the items in an QAbstractXmlForwardIterator needs to + * be translated to another sequence, while still doing it in a pipe-lined + * fashion. + * + * This is achieved by that ItemMappingIterator's constructor takes + * an instance of a class, that must have the following member: + * + * @code + * TResult::Ptr mapToItem(const TSource &item, + * const Context &context) const + * @endcode + * + * For each item in the QAbstractXmlForwardIterator ItemMappingIterator proxies, this function is + * called and its return value becomes the return value of the ItemMappingIterator. If the + * mapping function returns null, ItemMappingIterator maps the next item in the source sequence + * such that a contiguous sequence of items is returned. + * + * Declaring the mapToItem() function as inline, can be a good way to improve performance. + * + * @see SequenceMappingIterator + * @author Frans Englich <frans.englich@nokia.com> + * @ingroup Patternist_iterators + */ + template<typename TResult, typename TSource, typename TMapper, typename Context = DynamicContext::Ptr> + class ItemMappingIterator : public QAbstractXmlForwardIterator<TResult> + { + public: + /** + * Constructs an ItemMappingIterator. + * + * @param mapper the object that has the mapToItem() sequence. + * @param iterator the QAbstractXmlForwardIterator whose items should be mapped. + * @param context the context that will be passed to the map function. + * May be null. + */ + ItemMappingIterator(const TMapper &mapper, + const typename QAbstractXmlForwardIterator<TSource>::Ptr &iterator, + const Context &context) : m_mapper(mapper) + , m_it(iterator) + , m_context(context) + , m_position(0) + { + Q_ASSERT(mapper); + Q_ASSERT(iterator); + } + + /** + * @returns the next item in the sequence, or + * @c null if the end have been reached. + */ + virtual TResult next() + { + const TSource sourceItem(m_it->next()); + + if(qIsForwardIteratorEnd(sourceItem)) + { + m_current = TResult(); + m_position = -1; + return TResult(); + } + else + { + m_current = m_mapper->mapToItem(sourceItem, m_context); + if(qIsForwardIteratorEnd(m_current)) + return next(); /* The mapper returned null, so continue with the next in the source. */ + else + { + ++m_position; + return m_current; + } + } + } + + virtual TResult current() const + { + return m_current; + } + + virtual xsInteger position() const + { + return m_position; + } + + virtual typename QAbstractXmlForwardIterator<TResult>::Ptr copy() const + { + return typename QAbstractXmlForwardIterator<TResult>::Ptr + (new ItemMappingIterator<TResult, TSource, TMapper, Context>(m_mapper, m_it->copy(), m_context)); + } + + private: + const TMapper m_mapper; + const typename QAbstractXmlForwardIterator<TSource>::Ptr m_it; + const Context m_context; + TResult m_current; + xsInteger m_position; + }; + + /** + * @short An object generator for ItemMappingIterator. + * + * makeItemMappingIterator() is a convenience function for avoiding specifying + * the full template instantiation for ItemMappingIterator. Conceptually, it + * is identical to Qt's qMakePair(). + * + * @relates ItemMappingIterator + */ + template<typename TResult, typename TSource, typename TMapper, typename Context> + static inline + typename QAbstractXmlForwardIterator<TResult>::Ptr + makeItemMappingIterator(const TMapper &mapper, + const QExplicitlySharedDataPointer<QAbstractXmlForwardIterator<TSource> > &source, + const Context &context) + { + return typename QAbstractXmlForwardIterator<TResult>::Ptr + (new ItemMappingIterator<TResult, TSource, TMapper, Context>(mapper, source, context)); + } +} + +QT_END_NAMESPACE + +QT_END_HEADER + +#endif |