source: trunk/src/xmlpatterns/iterators/qitemmappingiterator_p.h@ 883

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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_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 <[email protected]>
     * @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.