/****************************************************************************+
−
**+
−
** Copyright (C) 2009 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_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 <frans.englich@nokia.com>+
−
     */+
−
    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.+
−
         *+
−
         * If the end has been reached, a default constructed pointer is+
−
         * returned.+
−
         *+
−
         * We intentionally return by reference.+
−
         */+
−
        inline Expression::Ptr next()+
−
        {+
−
            if(m_exprs.isEmpty())+
−
                return Expression::Ptr();+
−
+
−
            Level &lvl = m_exprs.top();+
−
            ++lvl.second;+
−
+
−
            if(lvl.second == lvl.first.size())+
−
            {+
−
                /* Resume iteration above us. */+
−
                m_exprs.pop();+
−
+
−
                if(m_exprs.isEmpty())+
−
                    return Expression::Ptr();+
−
+
−
                while(true)+
−
                {+
−
                    Level &previous = m_exprs.top();+
−
                    ++previous.second;+
−
+
−
                    if(previous.second < previous.first.count())+
−
                    {+
−
                        const Expression::Ptr &op = previous.first.at(previous.second);+
−
                        m_exprs.push(qMakePair(op->operands(), -1));+
−
                        return op;+
−
                    }+
−
                    else+
−
                    {+
−
                        // We have already reached the end of this level.+
−
                        m_exprs.pop();+
−
                        if(m_exprs.isEmpty())+
−
                            return Expression::Ptr();+
−
                    }+
−
                }+
−
            }+
−
            else+
−
            {+
−
                const Expression::Ptr &op = lvl.first.at(lvl.second);+
−
                m_exprs.push(qMakePair(op->operands(), -1));+
−
                return op;+
−
            }+
−
        }+
−
+
−
        /**+
−
         * Advances this iterator by the current expression and its operands.+
−
         */+
−
        Expression::Ptr skipOperands()+
−
        {+
−
            if(m_exprs.isEmpty())+
−
                return Expression::Ptr();+
−
+
−
            Level &lvl = m_exprs.top();+
−
            ++lvl.second;+
−
+
−
            if(lvl.second == lvl.first.size())+
−
            {+
−
                /* We've reached the end of this level, at least. */+
−
                m_exprs.pop();+
−
            }+
−
+
−
            return next();+
−
        }+
−
+
−
    private:+
−
        Q_DISABLE_COPY(OperandsIterator)+
−
+
−
        QStack<Level> m_exprs;+
−
    };+
−
}+
−
+
−
+
−
QT_END_NAMESPACE+
−
QT_END_HEADER+
−
+
−
#endif+
−