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39
40#include "qboolean_p.h"
41#include "qcommonsequencetypes_p.h"
42#include "qdynamiccontextstore_p.h"
43#include "qliteral_p.h"
44
45#include "qletclause_p.h"
46
47QT_BEGIN_NAMESPACE
48
49using namespace QPatternist;
50
51LetClause::LetClause(const Expression::Ptr &operand1,
52 const Expression::Ptr &operand2,
53 const VariableDeclaration::Ptr &decl) : PairContainer(operand1, operand2)
54 , m_varDecl(decl)
55{
56 Q_ASSERT(m_varDecl);
57}
58
59DynamicContext::Ptr LetClause::bindVariable(const DynamicContext::Ptr &context) const
60{
61 context->setExpressionVariable(slot: m_varDecl->slot, newValue: m_operand1);
62 return context;
63}
64
65Item::Iterator::Ptr LetClause::evaluateSequence(const DynamicContext::Ptr &context) const
66{
67 return m_operand2->evaluateSequence(context: bindVariable(context));
68}
69
70Item LetClause::evaluateSingleton(const DynamicContext::Ptr &context) const
71{
72 return m_operand2->evaluateSingleton(context: bindVariable(context));
73}
74
75bool LetClause::evaluateEBV(const DynamicContext::Ptr &context) const
76{
77 return m_operand2->evaluateEBV(context: bindVariable(context));
78}
79
80void LetClause::evaluateToSequenceReceiver(const DynamicContext::Ptr &context) const
81{
82 m_operand2->evaluateToSequenceReceiver(context: bindVariable(context));
83}
84
85Expression::Ptr LetClause::typeCheck(const StaticContext::Ptr &context,
86 const SequenceType::Ptr &reqType)
87{
88 /* Consider the following query:
89 *
90 * <tt>let $d := \<child type=""/>
91 * return $d//\*[let $i := @type
92 * return $d//\*[$i]]</tt>
93 *
94 * The node test <tt>@type</tt> is referenced from two different places,
95 * where each reference have a different focus. So, in the case of that the source
96 * uses the focus, we need to use a DynamicContextStore to ensure the variable
97 * is always evaluated with the correct focus, regardless of where it is referenced
98 * from.
99 *
100 * We miss out a lot of false positives. For instance, the case of where the focus
101 * is identical for everyone. One reason we cannot check this, is that Expression
102 * doesn't know about its parent.
103 */
104 m_varDecl->canSourceRewrite = !m_operand1->deepProperties().testFlag(flag: RequiresFocus);
105
106 if(m_varDecl->canSourceRewrite)
107 return m_operand2->typeCheck(context, reqType);
108 else
109 return PairContainer::typeCheck(context, reqType);
110}
111
112Expression::Properties LetClause::properties() const
113{
114 return m_varDecl->expression()->properties() & (Expression::RequiresFocus | Expression::IsEvaluated | Expression::DisableElimination);
115}
116
117SequenceType::List LetClause::expectedOperandTypes() const
118{
119 SequenceType::List result;
120 result.append(t: CommonSequenceTypes::ZeroOrMoreItems);
121 result.append(t: CommonSequenceTypes::ZeroOrMoreItems);
122 return result;
123}
124
125SequenceType::Ptr LetClause::staticType() const
126{
127 return m_operand2->staticType();
128}
129
130ExpressionVisitorResult::Ptr LetClause::accept(const ExpressionVisitor::Ptr &visitor) const
131{
132 return visitor->visit(this);
133}
134
135Expression::ID LetClause::id() const
136{
137 return IDLetClause;
138}
139
140QT_END_NAMESPACE
141

source code of qtxmlpatterns/src/xmlpatterns/expr/qletclause.cpp