/****************************************************************************+
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**+
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** Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).+
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** All rights reserved.+
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** Contact: Nokia Corporation (qt-info@nokia.com)+
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**+
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** This file is part of the QtXmlPatterns module of the Qt Toolkit.+
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**+
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** $QT_BEGIN_LICENSE:LGPL$+
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** No Commercial Usage+
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** This file contains pre-release code and may not be distributed.+
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** You may use this file in accordance with the terms and conditions+
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** contained in the Technology Preview License Agreement accompanying+
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** this package.+
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**+
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** GNU Lesser General Public License Usage+
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** Alternatively, this file may be used under the terms of the GNU Lesser+
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** General Public License version 2.1 as published by the Free Software+
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** Foundation and appearing in the file LICENSE.LGPL included in the+
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** packaging of this file.  Please review the following information to+
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** ensure the GNU Lesser General Public License version 2.1 requirements+
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** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.+
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**+
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** In addition, as a special exception, Nokia gives you certain additional+
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** rights.  These rights are described in the Nokia Qt LGPL Exception+
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** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.+
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**+
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** If you have questions regarding the use of this file, please contact+
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** Nokia at qt-info@nokia.com.+
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**+
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**+
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**+
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**+
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**+
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**+
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**+
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**+
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** $QT_END_LICENSE$+
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**+
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****************************************************************************/+
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+
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#include "qboolean_p.h"+
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#include "qcommonsequencetypes_p.h"+
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#include "qdynamiccontextstore_p.h"+
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#include "qliteral_p.h"+
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+
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#include "qletclause_p.h"+
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+
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QT_BEGIN_NAMESPACE+
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+
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using namespace QPatternist;+
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+
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LetClause::LetClause(const Expression::Ptr &operand1,+
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                     const Expression::Ptr &operand2,+
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                     const VariableDeclaration::Ptr &decl) : PairContainer(operand1, operand2)+
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                                                           , m_varDecl(decl)+
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{+
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    Q_ASSERT(m_varDecl);+
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}+
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+
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DynamicContext::Ptr LetClause::bindVariable(const DynamicContext::Ptr &context) const+
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{+
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    context->setExpressionVariable(m_varDecl->slot, Expression::Ptr(new DynamicContextStore(m_operand1, context)));+
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    return context;+
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}+
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+
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Item::Iterator::Ptr LetClause::evaluateSequence(const DynamicContext::Ptr &context) const+
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{+
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    return m_operand2->evaluateSequence(bindVariable(context));+
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}+
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+
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Item LetClause::evaluateSingleton(const DynamicContext::Ptr &context) const+
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{+
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    return m_operand2->evaluateSingleton(bindVariable(context));+
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}+
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+
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bool LetClause::evaluateEBV(const DynamicContext::Ptr &context) const+
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{+
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    return m_operand2->evaluateEBV(bindVariable(context));+
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}+
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+
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void LetClause::evaluateToSequenceReceiver(const DynamicContext::Ptr &context) const+
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{+
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    m_operand2->evaluateToSequenceReceiver(bindVariable(context));+
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}+
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+
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Expression::Ptr LetClause::typeCheck(const StaticContext::Ptr &context,+
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                                     const SequenceType::Ptr &reqType)+
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{+
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    /* Consider the following query:+
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     *+
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     * <tt>let $d := \<child type=""/>+
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     * return $d//\*[let $i := @type+
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     *              return $d//\*[$i]]</tt>+
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     *+
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     * The node test <tt>@type</tt> is referenced from two different places,+
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     * where each reference have a different focus. So, in the case of that the source+
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     * uses the focus, we need to use a DynamicContextStore to ensure the variable+
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     * is always evaluated with the correct focus, regardless of where it is referenced+
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     * from.+
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     *+
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     * We miss out a lot of false positives. For instance, the case of where the focus+
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     * is identical for everyone. One reason we cannot check this, is that Expression+
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     * doesn't know about its parent.+
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     */+
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    m_varDecl->canSourceRewrite = !m_operand1->deepProperties().testFlag(RequiresFocus);+
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+
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    if(m_varDecl->canSourceRewrite)+
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        return m_operand2->typeCheck(context, reqType);+
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    else+
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        return PairContainer::typeCheck(context, reqType);+
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}+
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+
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Expression::Properties LetClause::properties() const+
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{+
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    return m_varDecl->expression()->properties() & (Expression::RequiresFocus | Expression::IsEvaluated | Expression::DisableElimination);+
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}+
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+
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SequenceType::List LetClause::expectedOperandTypes() const+
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{+
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    SequenceType::List result;+
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    result.append(CommonSequenceTypes::ZeroOrMoreItems);+
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    result.append(CommonSequenceTypes::ZeroOrMoreItems);+
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    return result;+
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}+
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+
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SequenceType::Ptr LetClause::staticType() const+
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{+
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    return m_operand2->staticType();+
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}+
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+
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ExpressionVisitorResult::Ptr LetClause::accept(const ExpressionVisitor::Ptr &visitor) const+
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{+
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    return visitor->visit(this);+
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}+
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+
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Expression::ID LetClause::id() const+
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{+
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    return IDLetClause;+
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}+
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+
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QT_END_NAMESPACE+
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