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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)
commite5fcad302d86d316390c6b0f62759a067313e8a9 (patch)
treec2afbf6f1066b6ce261f14341cf6d310e5595bc1 /src/xmlpatterns/expr/qoperandsiterator_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_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 <fenglich@trolltech.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