/**************************************************************************** ** ** 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_OperandsIterator_H #define Patternist_OperandsIterator_H #include #include #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 */ class OperandsIterator { /** * The second value, the int, is the current position in the first. */ typedef QPair 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 m_exprs; }; } QT_END_NAMESPACE QT_END_HEADER #endif