source: trunk/src/xmlpatterns/expr/qoperandsiterator_p.h

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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_OperandsIterator_H
#define Patternist_OperandsIterator_H

#include <QPair>
#include <QStack>

#include "qexpression_p.h"

QT_BEGIN_HEADER

QT_BEGIN_NAMESPACE

namespace QPatternist
{
    /**
     * @short A helper class that iterates a tree of Expression instances. It
     * is not a sub-class of QAbstractXmlForwardIterator.
     *
     * The OperandsIterator delivers all Expression instances that are children at any
     * depth of the Expression passed in the constructor.
     * The order is delivered in a defined way, from left to right and depth
     * first.
     *
     * @author Frans Englich <[email protected]>
     */
    class OperandsIterator
    {
        /**
         * The second value, the int, is the current position in the first.
         */
        typedef QPair<Expression::List, int> Level;

    public:
        enum TreatParent
        {
            ExcludeParent,
            IncludeParent
        };

        /**
         * if @p treatParent is @c IncludeParent, @p start is excluded.
         *
         * @p start must be a valid Expression.
         */
        inline OperandsIterator(const Expression::Ptr &start,
                                const TreatParent treatParent)
        {
            Q_ASSERT(start);
            if(treatParent == IncludeParent)
            {
                Expression::List l;
                l.append(start);
                m_exprs.push(qMakePair(l, -1));
            }

            m_exprs.push(qMakePair(start->operands(), -1));
        }

        /**
         * @short Returns the current Expression and advances the iterator.