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/****************************************************************************
**
** Copyright (C) 2010 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 "qcommonsequencetypes_p.h"
#include "qemptysequence_p.h"
#include "qgenericsequencetype_p.h"
#include "qitemmappingiterator_p.h"
#include "qoptimizationpasses_p.h"
#include "qsequencemappingiterator_p.h"
#include "qforclause_p.h"
QT_BEGIN_NAMESPACE
using namespace QPatternist;
ForClause::ForClause(const VariableSlotID varSlot,
const Expression::Ptr &bindingSequence,
const Expression::Ptr &returnExpression,
const VariableSlotID positionSlot) : PairContainer(bindingSequence, returnExpression),
m_varSlot(varSlot),
m_positionSlot(positionSlot),
m_allowsMany(true)
{
Q_ASSERT(m_positionSlot > -2);
}
Item ForClause::mapToItem(const Item &item,
const DynamicContext::Ptr &context) const
{
context->setRangeVariable(m_varSlot, item);
return m_operand2->evaluateSingleton(context);
}
Item::Iterator::Ptr ForClause::mapToSequence(const Item &item,
const DynamicContext::Ptr &context) const
{
context->setRangeVariable(m_varSlot, item);
return m_operand2->evaluateSequence(context);
}
void ForClause::riggPositionalVariable(const DynamicContext::Ptr &context,
const Item::Iterator::Ptr &source) const
{
if(m_positionSlot > -1)
context->setPositionIterator(m_positionSlot, source);
}
Item::Iterator::Ptr ForClause::evaluateSequence(const DynamicContext::Ptr &context) const
{
const Item::Iterator::Ptr source(m_operand1->evaluateSequence(context));
riggPositionalVariable(context, source);
if(m_allowsMany)
{
return makeSequenceMappingIterator<Item>(ConstPtr(this),
source,
context);
}
else
{
return makeItemMappingIterator<Item>(ConstPtr(this),
source,
context);
}
}
Item ForClause::evaluateSingleton(const DynamicContext::Ptr &context) const
{
return evaluateSequence(context)->next();
}
void ForClause::evaluateToSequenceReceiver(const DynamicContext::Ptr &context) const
{
Item::Iterator::Ptr it;
const Item::Iterator::Ptr source(m_operand1->evaluateSequence(context));
riggPositionalVariable(context, source);
Item next(source->next());
while(next)
{
context->setRangeVariable(m_varSlot, next);
m_operand2->evaluateToSequenceReceiver(context);
next = source->next();
}
}
Expression::Ptr ForClause::typeCheck(const StaticContext::Ptr &context,
const SequenceType::Ptr &reqType)
{
const Expression::Ptr me(PairContainer::typeCheck(context, reqType));
const Cardinality card(m_operand1->staticType()->cardinality());
/* If our source is empty we will always evaluate to the empty sequence, so rewrite. */
if(card.isEmpty())
return EmptySequence::create(this, context);
else
return me;
/* This breaks because the variable references haven't rewritten themselves, so
* they dangle. When this is fixed, evaluateSingleton can be removed. */
/*
else if(card->allowsMany())
return me;
else
return m_operand2;
*/
}
Expression::Ptr ForClause::compress(const StaticContext::Ptr &context)
{
const Expression::Ptr me(PairContainer::compress(context));
if(me != this)
return me;
/* This is done after calling PairContainer::typeCheck(). The advantage of this is that
* m_allowsMany is updated according to what the operand says after it has compressed. However,
* if it was initialized to false(as it once was..), ForClause::evaluateSequence()
* would potentially have been called by PairContainer::compress(), and it would have
* used an unsafe branch. */
m_allowsMany = m_operand2->staticType()->cardinality().allowsMany();
return me;
}
SequenceType::Ptr ForClause::staticType() const
{
const SequenceType::Ptr returnType(m_operand2->staticType());
return makeGenericSequenceType(returnType->itemType(),
m_operand1->staticType()->cardinality()
* /* multiply operator */
returnType->cardinality());
}
SequenceType::List ForClause::expectedOperandTypes() const
{
SequenceType::List result;
result.append(CommonSequenceTypes::ZeroOrMoreItems);
result.append(CommonSequenceTypes::ZeroOrMoreItems);
return result;
}
ExpressionVisitorResult::Ptr ForClause::accept(const ExpressionVisitor::Ptr &visitor) const
{
return visitor->visit(this);
}
OptimizationPass::List ForClause::optimizationPasses() const
{
return OptimizationPasses::forPasses;
}
Expression::ID ForClause::id() const
{
return IDForClause;
}
QT_END_NAMESPACE
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