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     3 ** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).

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     7 ** This file is part of the QtXmlPatterns module of the Qt Toolkit.

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    40 ****************************************************************************/

    41 

    42 #include "qcommonsequencetypes_p.h"

    43 #include "qexceptiterator_p.h"

    44 #include "qgenericsequencetype_p.h"

    45 #include "qintersectiterator_p.h"

    46 #include "qitemmappingiterator_p.h"

    47 #include "qnodesort_p.h"

    48 #include "qunioniterator_p.h"

    49 

    50 #include "qcombinenodes_p.h"

    51 

    52 QT_BEGIN_NAMESPACE

    53 

    54 using namespace QPatternist;

    55 

    56 CombineNodes::CombineNodes(const Expression::Ptr &operand1,

    57                            const Operator op,

    58                            const Expression::Ptr &operand2) : PairContainer(operand1, operand2),

    59                                                               m_operator(op)

    60 {

    61     Q_ASSERT(op == Union    ||

    62              op == Except   ||

    63              op == Intersect);

    64 }

    65 

    66 Item::Iterator::Ptr CombineNodes::evaluateSequence(const DynamicContext::Ptr &context) const

    67 {

    68     const Item::Iterator::Ptr op1(m_operand1->evaluateSequence(context));

    69     const Item::Iterator::Ptr op2(m_operand2->evaluateSequence(context));

    70 

    71     switch(m_operator)

    72     {

    73         case Intersect:

    74             return Item::Iterator::Ptr(new IntersectIterator(op1, op2));

    75         case Except:

    76             return Item::Iterator::Ptr(new ExceptIterator(op1, op2));

    77         default:

    78         {

    79             Q_ASSERT(m_operator == Union);

    80             return Item::Iterator::Ptr(new UnionIterator(op1, op2));

    81         }

    82     }

    83 }

    84 

    85 Item CombineNodes::evaluateSingleton(const DynamicContext::Ptr &context) const

    86 {

    87     return evaluateSequence(context)->next();

    88 }

    89 

    90 Expression::Ptr CombineNodes::typeCheck(const StaticContext::Ptr &context,

    91                                         const SequenceType::Ptr &reqType)

    92 {

    93 

    94     const Expression::Ptr me(PairContainer::typeCheck(context, reqType));

    95 

    96     m_operand1 = NodeSortExpression::wrapAround(m_operand1, context);

    97     m_operand2 = NodeSortExpression::wrapAround(m_operand2, context);

    98 

    99     return me;

   100 }

   101 

   102 bool CombineNodes::evaluateEBV(const DynamicContext::Ptr &context) const

   103 {

   104     /* If it's the union operator, we can possibly avoid

   105      * evaluating the second operand. */

   106 

   107     if(m_operator == Union)

   108     {

   109         return m_operand1->evaluateEBV(context) ||

   110                m_operand2->evaluateEBV(context);

   111     }

   112     else

   113         return PairContainer::evaluateEBV(context);

   114 }

   115 

   116 QString CombineNodes::displayName(const Operator op)

   117 {

   118     switch(op)

   119     {

   120         case Intersect:

   121             return QLatin1String("intersect");

   122         case Except:

   123             return QLatin1String("except");

   124         default:

   125         {

   126             Q_ASSERT(op == Union);

   127             return QLatin1String("union");

   128         }

   129     }

   130 }

   131 

   132 SequenceType::Ptr CombineNodes::staticType() const

   133 {

   134     const SequenceType::Ptr t1(m_operand1->staticType());

   135     const SequenceType::Ptr t2(m_operand2->staticType());

   136 

   137      Cardinality card;

   138 

   139      /* Optimization: the cardinality can be better inferred for

   140       * Intersect and Except, although it's not trivial code. */

   141      if(m_operator == Union)

   142          card = t1->cardinality() | t2->cardinality();

   143      else /* Except. */

   144          card = Cardinality::zeroOrMore();

   145 

   146      return makeGenericSequenceType(t1->itemType() | t2->itemType(), card);

   147 }

   148 

   149 SequenceType::List CombineNodes::expectedOperandTypes() const

   150 {

   151     SequenceType::List result;

   152     result.append(CommonSequenceTypes::ZeroOrMoreNodes);

   153     result.append(CommonSequenceTypes::ZeroOrMoreNodes);

   154     return result;

   155 }

   156 

   157 CombineNodes::Operator CombineNodes::operatorID() const

   158 {

   159     return m_operator;

   160 }

   161 

   162 ExpressionVisitorResult::Ptr CombineNodes::accept(const ExpressionVisitor::Ptr &visitor) const

   163 {

   164     return visitor->visit(this);

   165 }

   166 

   167 Expression::ID CombineNodes::id() const

   168 {

   169     return IDCombineNodes;

   170 }

   171 

   172 QT_END_NAMESPACE