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42 #include "qboolean_p.h"
43 #include "qcommonsequencetypes_p.h"
44 #include "qdynamiccontextstore_p.h"
45 #include "qliteral_p.h"
47 #include "qletclause_p.h"
51 using namespace QPatternist;
53 LetClause::LetClause(const Expression::Ptr &operand1,
54 const Expression::Ptr &operand2,
55 const VariableDeclaration::Ptr &decl) : PairContainer(operand1, operand2)
61 DynamicContext::Ptr LetClause::bindVariable(const DynamicContext::Ptr &context) const
63 context->setExpressionVariable(m_varDecl->slot, Expression::Ptr(new DynamicContextStore(m_operand1, context)));
67 Item::Iterator::Ptr LetClause::evaluateSequence(const DynamicContext::Ptr &context) const
69 return m_operand2->evaluateSequence(bindVariable(context));
72 Item LetClause::evaluateSingleton(const DynamicContext::Ptr &context) const
74 return m_operand2->evaluateSingleton(bindVariable(context));
77 bool LetClause::evaluateEBV(const DynamicContext::Ptr &context) const
79 return m_operand2->evaluateEBV(bindVariable(context));
82 void LetClause::evaluateToSequenceReceiver(const DynamicContext::Ptr &context) const
84 m_operand2->evaluateToSequenceReceiver(bindVariable(context));
87 Expression::Ptr LetClause::typeCheck(const StaticContext::Ptr &context,
88 const SequenceType::Ptr &reqType)
90 /* Consider the following query:
92 * <tt>let $d := \<child type=""/>
93 * return $d//\*[let $i := @type
94 * return $d//\*[$i]]</tt>
96 * The node test <tt>@type</tt> is referenced from two different places,
97 * where each reference have a different focus. So, in the case of that the source
98 * uses the focus, we need to use a DynamicContextStore to ensure the variable
99 * is always evaluated with the correct focus, regardless of where it is referenced
102 * We miss out a lot of false positives. For instance, the case of where the focus
103 * is identical for everyone. One reason we cannot check this, is that Expression
104 * doesn't know about its parent.
106 m_varDecl->canSourceRewrite = !m_operand1->deepProperties().testFlag(RequiresFocus);
108 if(m_varDecl->canSourceRewrite)
109 return m_operand2->typeCheck(context, reqType);
111 return PairContainer::typeCheck(context, reqType);
114 Expression::Properties LetClause::properties() const
116 return m_varDecl->expression()->properties() & (Expression::RequiresFocus | Expression::IsEvaluated | Expression::DisableElimination);
119 SequenceType::List LetClause::expectedOperandTypes() const
121 SequenceType::List result;
122 result.append(CommonSequenceTypes::ZeroOrMoreItems);
123 result.append(CommonSequenceTypes::ZeroOrMoreItems);
127 SequenceType::Ptr LetClause::staticType() const
129 return m_operand2->staticType();
132 ExpressionVisitorResult::Ptr LetClause::accept(const ExpressionVisitor::Ptr &visitor) const
134 return visitor->visit(this);
137 Expression::ID LetClause::id() const