Qt 4.8
qfirstitempredicate.cpp
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41 
42 #include "qcommonsequencetypes_p.h"
43 #include "qgenericsequencetype_p.h"
44 
45 #include "qfirstitempredicate_p.h"
46 
48 
49 using namespace QPatternist;
50 
52 {
53 }
54 
56 {
57  /* If our operand allows the empty sequence, this function can return Item(), otherwise
58  * it returns the first item. As simple as that. */
59  return m_operand->evaluateSequence(context)->next();
60 }
61 
63 {
65  return makeGenericSequenceType(t->itemType(), t->cardinality().toWithoutMany());
66 }
67 
69 {
70  const Expression::Ptr me(SingleContainer::compress(context));
71  if(me != this)
72  return me;
73 
76 
77  return me;
78 }
79 
81 {
82  SequenceType::List result;
84  return result;
85 }
86 
88 {
89  return visitor->visit(this);
90 }
91 
93 {
94  return IDFirstItemPredicate;
95 }
96 
#define QT_END_NAMESPACE
This macro expands to.
Definition: qglobal.h:90
static const SequenceType::Ptr ZeroOrMoreItems
virtual ExpressionVisitorResult::Ptr accept(const ExpressionVisitor::Ptr &visitor) const
FirstItemPredicate(const Expression::Ptr &source)
virtual SequenceType::List expectedOperandTypes() const
virtual Expression::Ptr compress(const StaticContext::Ptr &context)
void append(const T &t)
Inserts value at the end of the list.
Definition: qlist.h:507
#define QT_BEGIN_NAMESPACE
This macro expands to.
Definition: qglobal.h:89
The namespace for the internal API of QtXmlPatterns.
virtual Expression::List operands() const =0
T & first()
Returns a reference to the first item in the list.
Definition: qlist.h:282
virtual SequenceType::Ptr staticType() const =0
Represents an item in the XPath 2.0 Data Model.
Definition: qitem_p.h:182
virtual SequenceType::Ptr staticType() const
virtual Item evaluateSingleton(const DynamicContext::Ptr &) const
virtual Expression::Ptr compress(const StaticContext::Ptr &context)
bool is(const ID id) const
The QList class is a template class that provides lists.
Definition: qdatastream.h:62
virtual Item::Iterator::Ptr evaluateSequence(const DynamicContext::Ptr &context) const
Base class for expressions that has exactly one operand.