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authorLars Knoll <lars.knoll@nokia.com>2009-03-23 09:18:55 (GMT)
committerSimon Hausmann <simon.hausmann@nokia.com>2009-03-23 09:18:55 (GMT)
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treec2afbf6f1066b6ce261f14341cf6d310e5595bc1 /src/xmlpatterns/iterators/qsequencemappingiterator_p.h
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Long live Qt 4.5!
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+/****************************************************************************
+**
+** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
+** Contact: Qt Software Information (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 either Technology Preview License Agreement or the
+** Beta Release License Agreement.
+**
+** 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 1.0, included in the file LGPL_EXCEPTION.txt in this
+** package.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3.0 as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU General Public License version 3.0 requirements will be
+** met: http://www.gnu.org/copyleft/gpl.html.
+**
+** If you are unsure which license is appropriate for your use, please
+** contact the sales department at qt-sales@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_SequenceMappingIterator_H
+#define Patternist_SequenceMappingIterator_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
+ * Sequence 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. In contrast to ItemMappingIterator, SequenceMappingIterator maps
+ * each item into another QAbstractXmlForwardIterator, and where the SequenceMappingIterator's own
+ * result is the concatenation of all those Iterators. Hence, while ItemMappingIterator
+ * is better tailored for one-to-one or one-to-zero conversion, SequenceMappingIterator
+ * is more suitable for one-to-many conversion.
+ *
+ * This is achieved by that SequenceMappingIterator's constructor takes
+ * an instance of a class, that must have the following member:
+ *
+ * @code
+ * QAbstractXmlForwardIterator<TResult>::Ptr mapToSequence(const TSource::Ptr &item,
+ * const DynamicContext::Ptr &context) const;
+ * @endcode
+ *
+ * @author Frans Englich <fenglich@trolltech.com>
+ * @see ItemMappingIterator
+ * @ingroup Patternist_iterators
+ */
+ template<typename TResult, typename TSource, typename TMapper>
+ class SequenceMappingIterator : public QAbstractXmlForwardIterator<TResult>
+ {
+ public:
+ /**
+ * Constructs a SequenceMappingIterator.
+ *
+ * @param mapper the object that has the mapToItem() sequence.
+ * @param sourceIterator the QAbstractXmlForwardIterator whose items should be mapped.
+ * @param context the DynamicContext that will be passed to the map function.
+ * May be null.
+ */
+ SequenceMappingIterator(const TMapper &mapper,
+ const typename QAbstractXmlForwardIterator<TSource>::Ptr &sourceIterator,
+ const DynamicContext::Ptr &context);
+
+ virtual TResult next();
+ virtual xsInteger count();
+ virtual TResult current() const;
+ virtual xsInteger position() const;
+
+ /**
+ * The reason the implementation is placed in line here, is due to a bug
+ * in MSVC-2005 version 14.00.50727.762. Note that it works with version 14.00.50727.42.
+ */
+ virtual typename QAbstractXmlForwardIterator<TResult>::Ptr copy() const
+ {
+ return typename QAbstractXmlForwardIterator<TResult>::Ptr
+ (new SequenceMappingIterator<TResult, TSource, TMapper>(m_mapper,
+ m_mainIterator->copy(),
+ m_context));
+ }
+
+ private:
+ xsInteger m_position;
+ TResult m_current;
+ typename QAbstractXmlForwardIterator<TSource>::Ptr m_mainIterator;
+ typename QAbstractXmlForwardIterator<TResult>::Ptr m_currentIterator;
+ const typename DynamicContext::Ptr m_context;
+ const TMapper m_mapper;
+ };
+
+ template<typename TResult, typename TSource, typename TMapper>
+ SequenceMappingIterator<TResult, TSource, TMapper>::SequenceMappingIterator(
+ const TMapper &mapper,
+ const typename QAbstractXmlForwardIterator<TSource>::Ptr &iterator,
+ const DynamicContext::Ptr &context)
+ : m_position(0),
+ m_mainIterator(iterator),
+ m_context(context),
+ m_mapper(mapper)
+ {
+ Q_ASSERT(mapper);
+ Q_ASSERT(iterator);
+ }
+
+ template<typename TResult, typename TSource, typename TMapper>
+ TResult SequenceMappingIterator<TResult, TSource, TMapper>::next()
+ {
+ /* This was once implemented with a recursive function, but the stack
+ * got blown for some inputs by that approach. */
+ while(true)
+ {
+ while(!m_currentIterator)
+ {
+ const TSource mainItem(m_mainIterator->next());
+
+ if(qIsForwardIteratorEnd(mainItem)) /* We've reached the very end. */
+ {
+ m_position = -1;
+ m_current = TResult();
+ return TResult();
+ }
+ else
+ m_currentIterator = m_mapper->mapToSequence(mainItem, m_context);
+ }
+
+ m_current = m_currentIterator->next();
+
+ if(qIsForwardIteratorEnd(m_current))
+ {
+ m_currentIterator.reset();
+ continue;
+ }
+ else
+ {
+ ++m_position;
+ return m_current;
+ }
+ }
+ }
+
+ template<typename TResult, typename TSource, typename TMapper>
+ xsInteger SequenceMappingIterator<TResult, TSource, TMapper>::count()
+ {
+ TSource unit(m_mainIterator->next());
+ xsInteger c = 0;
+
+ while(!qIsForwardIteratorEnd(unit))
+ {
+ const typename QAbstractXmlForwardIterator<TResult>::Ptr sit(m_mapper->mapToSequence(unit, m_context));
+ c += sit->count();
+ unit = m_mainIterator->next();
+ }
+
+ return c;
+ }
+
+ template<typename TResult, typename TSource, typename TMapper>
+ TResult SequenceMappingIterator<TResult, TSource, TMapper>::current() const
+ {
+ return m_current;
+ }
+
+ template<typename TResult, typename TSource, typename TMapper>
+ xsInteger SequenceMappingIterator<TResult, TSource, TMapper>::position() const
+ {
+ return m_position;
+ }
+
+
+ /**
+ * @short An object generator for SequenceMappingIterator.
+ *
+ * makeSequenceMappingIterator() is a convenience function for avoiding specifying
+ * the full template instantiation for SequenceMappingIterator. Conceptually, it
+ * is identical to Qt's qMakePair().
+ *
+ * @returns a SequenceMappingIterator wrapped in a smart pointer, that has been
+ * passed the constructor arguments @p mapper, @p source, and @p context.
+ * @see makeMappingCallbackPtr()
+ * @relates QAbstractXmlForwardIterator
+ */
+ template<typename TResult, typename TSource, typename TMapper>
+ static inline
+ typename QAbstractXmlForwardIterator<TResult>::Ptr
+ makeSequenceMappingIterator(const TMapper &mapper,
+ const QExplicitlySharedDataPointer<QAbstractXmlForwardIterator<TSource> > &source,
+ const DynamicContext::Ptr &context)
+ {
+ return typename QAbstractXmlForwardIterator<TResult>::Ptr
+ (new SequenceMappingIterator<TResult, TSource, TMapper>(mapper, source, context));
+ }
+}
+
+QT_END_NAMESPACE
+
+QT_END_HEADER
+
+#endif