src/xmlpatterns/expr/qinstanceof.cpp
changeset 0 1918ee327afb
child 4 3b1da2848fc7
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/xmlpatterns/expr/qinstanceof.cpp	Mon Jan 11 14:00:40 2010 +0000
@@ -0,0 +1,129 @@
+/****************************************************************************
+**
+** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
+** All rights reserved.
+** Contact: Nokia Corporation (qt-info@nokia.com)
+**
+** This file is part of the QtXmlPatterns module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** No Commercial Usage
+** This file contains pre-release code and may not be distributed.
+** You may use this file in accordance with the terms and conditions
+** contained in the Technology Preview License Agreement accompanying
+** this package.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Nokia gives you certain additional
+** rights.  These rights are described in the Nokia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** If you have questions regarding the use of this file, please contact
+** Nokia at qt-info@nokia.com.
+**
+**
+**
+**
+**
+**
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "qboolean_p.h"
+#include "qcommonsequencetypes_p.h"
+#include "qcommonvalues_p.h"
+#include "qliteral_p.h"
+
+#include "qinstanceof_p.h"
+
+QT_BEGIN_NAMESPACE
+
+using namespace QPatternist;
+
+InstanceOf::InstanceOf(const Expression::Ptr &operand,
+                       const SequenceType::Ptr &tType) : SingleContainer(operand)
+                                                       , m_targetType(tType)
+{
+    Q_ASSERT(m_targetType);
+}
+
+bool InstanceOf::evaluateEBV(const DynamicContext::Ptr &context) const
+{
+    const Item::Iterator::Ptr it(m_operand->evaluateSequence(context));
+    Item item(it->next());
+    unsigned int count = 1;
+
+    if(!item)
+        return m_targetType->cardinality().allowsEmpty();
+
+    do
+    {
+        if(!m_targetType->itemType()->itemMatches(item))
+            return false;
+
+        if(count == 2 && !m_targetType->cardinality().allowsMany())
+            return false;
+
+        item = it->next();
+        ++count;
+    } while(item);
+
+    return true;
+}
+
+Expression::Ptr InstanceOf::compress(const StaticContext::Ptr &context)
+{
+    const Expression::Ptr me(SingleContainer::compress(context));
+
+    if(me != this || m_operand->has(DisableTypingDeduction))
+        return me;
+
+    const SequenceType::Ptr opType(m_operand->staticType());
+    const ItemType::Ptr targetType(m_targetType->itemType());
+    const ItemType::Ptr operandType(opType->itemType());
+
+    if(m_targetType->cardinality().isMatch(opType->cardinality()))
+    {
+        if(*operandType == *CommonSequenceTypes::Empty || targetType->xdtTypeMatches(operandType))
+            return wrapLiteral(CommonValues::BooleanTrue, context, this);
+        else if(!operandType->xdtTypeMatches(targetType))
+            return wrapLiteral(CommonValues::BooleanFalse, context, this);
+    }
+    /* Optimization: rule out the case where instance of will always fail. */
+
+    return me;
+}
+
+SequenceType::Ptr InstanceOf::targetType() const
+{
+    return m_targetType;
+}
+
+SequenceType::Ptr InstanceOf::staticType() const
+{
+    return CommonSequenceTypes::ExactlyOneBoolean;
+}
+
+SequenceType::List InstanceOf::expectedOperandTypes() const
+{
+    SequenceType::List result;
+    result.append(CommonSequenceTypes::ZeroOrMoreItems);
+    return result;
+}
+
+ExpressionVisitorResult::Ptr InstanceOf::accept(const ExpressionVisitor::Ptr &visitor) const
+{
+    return visitor->visit(this);
+}
+
+QT_END_NAMESPACE