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46 // This file is not part of the Qt API. It exists purely as an
47 // implementation detail. This header file may change from version to
48 // version without notice, or even be removed.
52 #ifndef Patternist_OperandsIterator_H
53 #define Patternist_OperandsIterator_H
58 #include <private/qexpression_p.h>
67 * @short A helper class that iterates a tree of Expression instances. It
68 * is not a sub-class of QAbstractXmlForwardIterator.
70 * The OperandsIterator delivers all Expression instances that are children at any
71 * depth of the Expression passed in the constructor.
72 * The order is delivered in a defined way, from left to right and depth
75 * @author Frans Englich <frans.englich@nokia.com>
77 class OperandsIterator
80 * The second value, the int, is the current position in the first.
82 typedef QPair<Expression::List, int> Level;
92 * if @p treatParent is @c IncludeParent, @p start is excluded.
94 * @p start must be a valid Expression.
96 inline OperandsIterator(const Expression::Ptr &start,
97 const TreatParent treatParent)
100 if(treatParent == IncludeParent)
104 m_exprs.push(qMakePair(l, -1));
107 m_exprs.push(qMakePair(start->operands(), -1));
111 * @short Returns the current Expression and advances the iterator.
113 * If the end has been reached, a default constructed pointer is
116 * We intentionally return by reference.
118 inline Expression::Ptr next()
120 if(m_exprs.isEmpty())
121 return Expression::Ptr();
123 Level &lvl = m_exprs.top();
126 if(lvl.second == lvl.first.size())
128 /* Resume iteration above us. */
131 if(m_exprs.isEmpty())
132 return Expression::Ptr();
136 Level &previous = m_exprs.top();
139 if(previous.second < previous.first.count())
141 const Expression::Ptr &op = previous.first.at(previous.second);
142 m_exprs.push(qMakePair(op->operands(), -1));
147 // We have already reached the end of this level.
149 if(m_exprs.isEmpty())
150 return Expression::Ptr();
156 const Expression::Ptr &op = lvl.first.at(lvl.second);
157 m_exprs.push(qMakePair(op->operands(), -1));
163 * Advances this iterator by the current expression and its operands.
165 Expression::Ptr skipOperands()
167 if(m_exprs.isEmpty())
168 return Expression::Ptr();
170 Level &lvl = m_exprs.top();
173 if(lvl.second == lvl.first.size())
175 /* We've reached the end of this level, at least. */
183 Q_DISABLE_COPY(OperandsIterator)
185 QStack<Level> m_exprs;