src/xmlpatterns/expr/qcastableas.cpp
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     1 /****************************************************************************
       
     2 **
       
     3 ** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
       
     4 ** All rights reserved.
       
     5 ** Contact: Nokia Corporation (qt-info@nokia.com)
       
     6 **
       
     7 ** This file is part of the QtXmlPatterns module of the Qt Toolkit.
       
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     9 ** $QT_BEGIN_LICENSE:LGPL$
       
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    16 ** GNU Lesser General Public License Usage
       
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    20 ** packaging of this file.  Please review the following information to
       
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    33 **
       
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    36 **
       
    37 **
       
    38 ** $QT_END_LICENSE$
       
    39 **
       
    40 ****************************************************************************/
       
    41 
       
    42 #include "qatomictype_p.h"
       
    43 #include "qitem_p.h"
       
    44 #include "qboolean_p.h"
       
    45 #include "qbuiltintypes_p.h"
       
    46 #include "qcommonsequencetypes_p.h"
       
    47 #include "qcommonvalues_p.h"
       
    48 #include "qliteral_p.h"
       
    49 
       
    50 #include "qcastableas_p.h"
       
    51 
       
    52 QT_BEGIN_NAMESPACE
       
    53 
       
    54 using namespace QPatternist;
       
    55 
       
    56 CastableAs::CastableAs(const Expression::Ptr &operand,
       
    57                        const SequenceType::Ptr &tType) : SingleContainer(operand),
       
    58                                                          m_targetType(tType)
       
    59 {
       
    60     Q_ASSERT(tType);
       
    61     Q_ASSERT(!tType->cardinality().allowsMany());
       
    62     Q_ASSERT(tType->itemType()->isAtomicType());
       
    63 }
       
    64 
       
    65 bool CastableAs::evaluateEBV(const DynamicContext::Ptr &context) const
       
    66 {
       
    67     Item item;
       
    68 
       
    69     if(m_operand->staticType()->cardinality().allowsMany())
       
    70     {
       
    71         const Item::Iterator::Ptr it(m_operand->evaluateSequence(context));
       
    72         item = it->next();
       
    73 
       
    74         if(it->next())
       
    75             return false;
       
    76     }
       
    77     else
       
    78         item = m_operand->evaluateSingleton(context);
       
    79 
       
    80     if(item)
       
    81         return !cast(item, context).as<AtomicValue>()->hasError();
       
    82     else
       
    83         return m_targetType->cardinality().allowsEmpty();
       
    84 }
       
    85 
       
    86 Expression::Ptr CastableAs::compress(const StaticContext::Ptr &context)
       
    87 {
       
    88     const Expression::Ptr me(SingleContainer::compress(context));
       
    89 
       
    90     if(me != this) /* We already managed to const fold, how convenient. */
       
    91         return me;
       
    92 
       
    93     const AtomicType::Ptr t(m_targetType->itemType());
       
    94 
       
    95     const SequenceType::Ptr opType(m_operand->staticType());
       
    96 
       
    97     /* Casting to these always succeeds, assuming the cardinality also matches,
       
    98      * although the cardinality can fail. */
       
    99     if((   *t == *BuiltinTypes::xsString
       
   100         || *t == *BuiltinTypes::xsUntypedAtomic
       
   101         || *t == *opType->itemType())
       
   102        &&(m_targetType->cardinality().isMatch(opType->cardinality())))
       
   103     {
       
   104         return wrapLiteral(CommonValues::BooleanTrue, context, this);
       
   105     }
       
   106     else
       
   107         return me;
       
   108 }
       
   109 
       
   110 Expression::Ptr CastableAs::typeCheck(const StaticContext::Ptr &context,
       
   111                                       const SequenceType::Ptr &reqType)
       
   112 {
       
   113     checkTargetType(context);
       
   114     const Expression::Ptr me(SingleContainer::typeCheck(context, reqType));
       
   115 
       
   116     return me;
       
   117     if(BuiltinTypes::xsQName->xdtTypeMatches(m_targetType->itemType()))
       
   118     {
       
   119         const SequenceType::Ptr seqt(m_operand->staticType());
       
   120         /* We can cast a string literal, an xs:QName value, and an
       
   121          * empty sequence(if empty is allowed), to xs:QName. */
       
   122         if(m_operand->is(IDStringValue) ||
       
   123            BuiltinTypes::xsQName->xdtTypeMatches(seqt->itemType()) ||
       
   124            (*seqt->itemType() == *CommonSequenceTypes::Empty && m_targetType->cardinality().allowsEmpty()))
       
   125         {
       
   126             return wrapLiteral(CommonValues::BooleanTrue, context, this)->typeCheck(context, reqType);
       
   127         }
       
   128         else
       
   129             return wrapLiteral(CommonValues::BooleanFalse, context, this)->typeCheck(context, reqType);
       
   130     }
       
   131     else
       
   132     {
       
   133         /* Let the CastingPlatform look up its AtomicCaster. */
       
   134         prepareCasting(context, m_operand->staticType()->itemType());
       
   135 
       
   136         return me;
       
   137     }
       
   138 }
       
   139 
       
   140 SequenceType::List CastableAs::expectedOperandTypes() const
       
   141 {
       
   142     SequenceType::List result;
       
   143     result.append(CommonSequenceTypes::ZeroOrMoreAtomicTypes);
       
   144     return result;
       
   145 }
       
   146 
       
   147 SequenceType::Ptr CastableAs::staticType() const
       
   148 {
       
   149     return CommonSequenceTypes::ExactlyOneBoolean;
       
   150 }
       
   151 
       
   152 ExpressionVisitorResult::Ptr CastableAs::accept(const ExpressionVisitor::Ptr &visitor) const
       
   153 {
       
   154     return visitor->visit(this);
       
   155 }
       
   156 
       
   157 QT_END_NAMESPACE