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/****************************************************************************
**
** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
** 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 "qdynamiccontextstore_p.h"
#include "qliteral_p.h"
#include "qletclause_p.h"
QT_BEGIN_NAMESPACE
using namespace QPatternist;
LetClause::LetClause(const Expression::Ptr &operand1,
const Expression::Ptr &operand2,
const VariableDeclaration::Ptr &decl) : PairContainer(operand1, operand2)
, m_varDecl(decl)
{
Q_ASSERT(m_varDecl);
}
DynamicContext::Ptr LetClause::bindVariable(const DynamicContext::Ptr &context) const
{
context->setExpressionVariable(m_varDecl->slot, Expression::Ptr(new DynamicContextStore(m_operand1, context)));
return context;
}
Item::Iterator::Ptr LetClause::evaluateSequence(const DynamicContext::Ptr &context) const
{
return m_operand2->evaluateSequence(bindVariable(context));
}
Item LetClause::evaluateSingleton(const DynamicContext::Ptr &context) const
{
return m_operand2->evaluateSingleton(bindVariable(context));
}
bool LetClause::evaluateEBV(const DynamicContext::Ptr &context) const
{
return m_operand2->evaluateEBV(bindVariable(context));
}
void LetClause::evaluateToSequenceReceiver(const DynamicContext::Ptr &context) const
{
m_operand2->evaluateToSequenceReceiver(bindVariable(context));
}
Expression::Ptr LetClause::typeCheck(const StaticContext::Ptr &context,
const SequenceType::Ptr &reqType)
{
/* Consider the following query:
*
* <tt>let $d := \<child type=""/>
* return $d//\*[let $i := @type
* return $d//\*[$i]]</tt>
*
* The node test <tt>@type</tt> is referenced from two different places,
* where each reference have a different focus. So, in the case of that the source
* uses the focus, we need to use a DynamicContextStore to ensure the variable
* is always evaluated with the correct focus, regardless of where it is referenced
* from.
*
* We miss out a lot of false positives. For instance, the case of where the focus
* is identical for everyone. One reason we cannot check this, is that Expression
* doesn't know about its parent.
*/
m_varDecl->canSourceRewrite = !m_operand1->deepProperties().testFlag(RequiresFocus);
if(m_varDecl->canSourceRewrite)
return m_operand2->typeCheck(context, reqType);
else
return PairContainer::typeCheck(context, reqType);
}
Expression::Properties LetClause::properties() const
{
return m_varDecl->expression()->properties() & (Expression::RequiresFocus | Expression::IsEvaluated | Expression::DisableElimination);
}
SequenceType::List LetClause::expectedOperandTypes() const
{
SequenceType::List result;
result.append(CommonSequenceTypes::ZeroOrMoreItems);
result.append(CommonSequenceTypes::ZeroOrMoreItems);
return result;
}
SequenceType::Ptr LetClause::staticType() const
{
return m_operand2->staticType();
}
ExpressionVisitorResult::Ptr LetClause::accept(const ExpressionVisitor::Ptr &visitor) const
{
return visitor->visit(this);
}
Expression::ID LetClause::id() const
{
return IDLetClause;
}
QT_END_NAMESPACE
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