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    41 

    42 #include "qboolean_p.h"

    43 #include "qcommonsequencetypes_p.h"

    44 #include "qdynamiccontextstore_p.h"

    45 #include "qliteral_p.h"

    46 

    47 #include "qletclause_p.h"

    48 

    49 QT_BEGIN_NAMESPACE

    50 

    51 using namespace QPatternist;

    52 

    53 LetClause::LetClause(const Expression::Ptr &operand1,

    54                      const Expression::Ptr &operand2,

    55                      const VariableDeclaration::Ptr &decl) : PairContainer(operand1, operand2)

    56                                                            , m_varDecl(decl)

    57 {

    58     Q_ASSERT(m_varDecl);

    59 }

    60 

    61 DynamicContext::Ptr LetClause::bindVariable(const DynamicContext::Ptr &context) const

    62 {

    63     context->setExpressionVariable(m_varDecl->slot, Expression::Ptr(new DynamicContextStore(m_operand1, context)));

    64     return context;

    65 }

    66 

    67 Item::Iterator::Ptr LetClause::evaluateSequence(const DynamicContext::Ptr &context) const

    68 {

    69     return m_operand2->evaluateSequence(bindVariable(context));

    70 }

    71 

    72 Item LetClause::evaluateSingleton(const DynamicContext::Ptr &context) const

    73 {

    74     return m_operand2->evaluateSingleton(bindVariable(context));

    75 }

    76 

    77 bool LetClause::evaluateEBV(const DynamicContext::Ptr &context) const

    78 {

    79     return m_operand2->evaluateEBV(bindVariable(context));

    80 }

    81 

    82 void LetClause::evaluateToSequenceReceiver(const DynamicContext::Ptr &context) const

    83 {

    84     m_operand2->evaluateToSequenceReceiver(bindVariable(context));

    85 }

    86 

    87 Expression::Ptr LetClause::typeCheck(const StaticContext::Ptr &context,

    88                                      const SequenceType::Ptr &reqType)

    89 {

    90     /* Consider the following query:

    91      *

    92      * <tt>let $d := \<child type=""/>

    93      * return $d//\*[let $i := @type

    94      *              return $d//\*[$i]]</tt>

    95      *

    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

   100      * from.

   101      *

   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.

   105      */

   106     m_varDecl->canSourceRewrite = !m_operand1->deepProperties().testFlag(RequiresFocus);

   107 

   108     if(m_varDecl->canSourceRewrite)

   109         return m_operand2->typeCheck(context, reqType);

   110     else

   111         return PairContainer::typeCheck(context, reqType);

   112 }

   113 

   114 Expression::Properties LetClause::properties() const

   115 {

   116     return m_varDecl->expression()->properties() & (Expression::RequiresFocus | Expression::IsEvaluated | Expression::DisableElimination);

   117 }

   118 

   119 SequenceType::List LetClause::expectedOperandTypes() const

   120 {

   121     SequenceType::List result;

   122     result.append(CommonSequenceTypes::ZeroOrMoreItems);

   123     result.append(CommonSequenceTypes::ZeroOrMoreItems);

   124     return result;

   125 }

   126 

   127 SequenceType::Ptr LetClause::staticType() const

   128 {

   129     return m_operand2->staticType();

   130 }

   131 

   132 ExpressionVisitorResult::Ptr LetClause::accept(const ExpressionVisitor::Ptr &visitor) const

   133 {

   134     return visitor->visit(this);

   135 }

   136 

   137 Expression::ID LetClause::id() const

   138 {

   139     return IDLetClause;

   140 }

   141 

   142 QT_END_NAMESPACE