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

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    41 

    42 //

    43 //  W A R N I N G

    44 //  -------------

    45 //

    46 // This file is not part of the Qt API.  It exists purely as an

    47 // implementation detail.  This header file may change from version to

    48 // version without notice, or even be removed.

    49 //

    50 // We mean it.

    51 

    52 #ifndef Patternist_UnlimitedContainer_H

    53 #define Patternist_UnlimitedContainer_H

    54 

    55 #include <QList>

    56 #include "qexpression_p.h"

    57 #include "qgenericsequencetype_p.h"

    58 

    59 QT_BEGIN_HEADER

    60 

    61 QT_BEGIN_NAMESPACE

    62 

    63 namespace QPatternist

    64 {

    65     /**

    66      * @short Base class for expressions that has any amount of operands.

    67      *

    68      * @author Frans Englich <frans.englich@nokia.com>

    69      * @ingroup Patternist_expressions

    70      */

    71     class UnlimitedContainer : public Expression

    72     {

    73     public:

    74         /**

    75          * Creates an UnlimitedContainer containing the operands @p operands. @p operands

    76          * may be empty.

    77          */

    78         UnlimitedContainer(const Expression::List &operands = Expression::List());

    79 

    80         virtual void setOperands(const Expression::List &list);

    81 

    82         virtual Expression::List operands() const;

    83 

    84         /**

    85          * @note This function cannot be called before setOperands is called.

    86          */

    87         virtual bool compressOperands(const StaticContext::Ptr &);

    88 

    89         /**

    90          * Tells how operandsUnionType() should compute the cardinality of

    91          * its children.

    92          *

    93          * This type is public because of a bug in the HP-UX aCC compiler.

    94          */

    95         enum CardinalityComputation

    96         {

    97             ProductOfCardinality,

    98             UnionOfCardinality

    99         };

   100 

   101     protected:

   102         /**

   103          * Computes and returns the union type of all the Expression instances

   104          * in this Expression's operands.

   105          *

   106          * This implementation is placed inside because CardinalityComputation

   107          * can't be referenced from the outside(in conforming compilers).

   108          */

   109         template<CardinalityComputation suppliedCard>

   110         inline

   111         SequenceType::Ptr operandsUnionType() const

   112         {

   113             Q_ASSERT(suppliedCard ==  ProductOfCardinality || suppliedCard == UnionOfCardinality);

   114             const Expression::List::const_iterator end(m_operands.constEnd());

   115             Expression::List::const_iterator it(m_operands.constBegin());

   116 

   117             /* Load the first one, and jump over it in the loop. */

   118             SequenceType::Ptr t(m_operands.first()->staticType());

   119             ItemType::Ptr type(t->itemType());

   120             Cardinality card(t->cardinality());

   121             ++it;

   122 

   123             for(; it != end; ++it)

   124             {

   125                 t = (*it)->staticType();

   126                 type |= t->itemType();

   127 

   128                 /* Since this function is a template function, it doesn't

   129                  * hurt performance that this test is inside the loop. */

   130                 if(suppliedCard == ProductOfCardinality)

   131                     card += t->cardinality();

   132                 else

   133                     card |= t->cardinality();

   134             }

   135 

   136             return makeGenericSequenceType(type, card);

   137         }

   138 

   139         Expression::List m_operands;

   140     };

   141 

   142 

   143 }

   144 

   145 QT_END_NAMESPACE

   146 

   147 QT_END_HEADER

   148 

   149 #endif