/****************************************************************************+
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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 <QtAlgorithms>+
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+
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#include "qcommonsequencetypes_p.h"+
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#include "qnodebuilder_p.h"+
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#include "qschemanumeric_p.h"+
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#include "qpatternistlocale_p.h"+
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#include "qreturnorderby_p.h"+
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#include "qsorttuple_p.h"+
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#include "qsequencemappingiterator_p.h"+
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+
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#include "qorderby_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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OrderBy::OrderBy(const Stability stability,+
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                 const OrderSpec::Vector &aOrderSpecs,+
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                 const Expression::Ptr &op,+
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                 ReturnOrderBy *const returnOrderBy) : SingleContainer(op)+
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                                                     , m_stability(stability)+
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                                                     , m_orderSpecs(aOrderSpecs)+
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                                                     , m_returnOrderBy(returnOrderBy)+
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{+
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    Q_ASSERT(m_returnOrderBy);+
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}+
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+
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void OrderBy::OrderSpec::prepare(const Expression::Ptr &source,+
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                                 const StaticContext::Ptr &context)+
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{+
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    m_expr = source;+
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    const ItemType::Ptr t(source->staticType()->itemType());+
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    prepareComparison(fetchComparator(t, t, context));+
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}+
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+
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/**+
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 * @short Functor used by Qt's qSort() and qStableSort(). Used for FLWOR's+
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 * <tt>order by</tt> expression.+
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 *+
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 * This must be in the global namespace, since it is specializing qLess(), which+
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 * is in the global namespace. Hence it can't be in QPatternist.+
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 */+
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template<>+
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class qLess<Item::List>+
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{+
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private:+
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+
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    static inline bool isNaN(const Item &i)+
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    {+
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        return BuiltinTypes::xsDouble->xdtTypeMatches(i.type()) &&+
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               i.as<Numeric>()->isNaN();+
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    }+
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+
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public:+
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    inline qLess(const OrderBy::OrderSpec::Vector &orderspecs,+
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                 const DynamicContext::Ptr &context) : m_orderSpecs(orderspecs)+
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                                                     , m_context(context)+
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    {+
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        Q_ASSERT(!m_orderSpecs.isEmpty());+
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        Q_ASSERT(context);+
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    }+
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+
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    inline bool operator()(const Item &item1, const Item &item2) const+
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    {+
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        const SortTuple *const s1 = item1.as<SortTuple>();+
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        const SortTuple *const s2 = item2.as<SortTuple>();+
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+
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        const Item::Vector &sortKeys1 = s1->sortKeys();+
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        const Item::Vector &sortKeys2 = s2->sortKeys();+
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        const int len = sortKeys1.count();+
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        Q_ASSERT(sortKeys1.count() == sortKeys2.count());+
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+
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        for(int i = 0; i < len; ++i)+
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        {+
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            const Item &i1 = sortKeys1.at(i);+
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            const Item &i2 = sortKeys2.at(i);+
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            const OrderBy::OrderSpec &orderSpec = m_orderSpecs.at(i);+
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+
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            if(!i1)+
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            {+
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                if(i2 && !isNaN(i2))+
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                {+
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                    /* We got ((), item()). */+
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                    return orderSpec.orderingEmptySequence == StaticContext::Least ? orderSpec.direction == OrderBy::OrderSpec::Ascending+
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                                                                                   : orderSpec.direction != OrderBy::OrderSpec::Ascending;+
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                }+
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                else+
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                    return false;+
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            }+
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+
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            if(!i2)+
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            {+
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                if(i1 && !isNaN(i1))+
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                    /* We got (item(), ()). */+
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                    return orderSpec.orderingEmptySequence == StaticContext::Greatest ? orderSpec.direction == OrderBy::OrderSpec::Ascending+
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                                                                                      : orderSpec.direction != OrderBy::OrderSpec::Ascending;+
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                else+
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                    return false;+
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            }+
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+
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            Q_ASSERT(orderSpec.direction == OrderBy::OrderSpec::Ascending ||+
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                     orderSpec.direction == OrderBy::OrderSpec::Descending);+
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            const AtomicComparator::ComparisonResult result = orderSpec.detailedFlexibleCompare(i1, i2, m_context);+
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+
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            switch(result)+
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            {+
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                case AtomicComparator::LessThan:+
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                    return orderSpec.direction == OrderBy::OrderSpec::Ascending;+
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                case AtomicComparator::GreaterThan:+
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                    return orderSpec.direction != OrderBy::OrderSpec::Ascending;+
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                case AtomicComparator::Equal:+
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                    continue;+
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                case AtomicComparator::Incomparable:+
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                    Q_ASSERT_X(false, Q_FUNC_INFO, "This code path assume values are always comparable.");+
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            }+
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        }+
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+
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        return false;+
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    }+
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+
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private:+
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    /* Yes, we store references here. */+
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    const OrderBy::OrderSpec::Vector & m_orderSpecs;+
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    const DynamicContext::Ptr & m_context;+
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};+
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+
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Item::Iterator::Ptr OrderBy::mapToSequence(const Item &i,+
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                                           const DynamicContext::Ptr &) const+
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{+
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    return i.as<SortTuple>()->value();+
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}+
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+
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Item::Iterator::Ptr OrderBy::evaluateSequence(const DynamicContext::Ptr &context) const+
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{+
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    Item::List tuples(m_operand->evaluateSequence(context)->toList());+
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+
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    const qLess<Item::List> sorter(m_orderSpecs, context);+
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+
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    Q_ASSERT(m_stability == StableOrder || m_stability == UnstableOrder);+
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+
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    /* On one hand we could just disregard stability and always use qStableSort(), but maybe qSort()+
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     * is a bit faster? */+
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    if(m_stability == StableOrder)+
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        qStableSort(tuples.begin(), tuples.end(), sorter);+
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    else+
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    {+
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        Q_ASSERT(m_stability == UnstableOrder);+
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        qSort(tuples.begin(), tuples.end(), sorter);+
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    }+
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+
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    return makeSequenceMappingIterator<Item>(ConstPtr(this),+
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                                             makeListIterator(tuples),+
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                                             context);+
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}+
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+
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Expression::Ptr OrderBy::typeCheck(const StaticContext::Ptr &context,+
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                                   const SequenceType::Ptr &reqType)+
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{+
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    m_returnOrderBy->setStay(true);+
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+
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    /* It's important we do the typeCheck() before calling OrderSpec::prepare(), since+
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     * atomizers must first be inserted. */+
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    const Expression::Ptr me(SingleContainer::typeCheck(context, reqType));+
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+
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    const Expression::List ops(m_returnOrderBy->operands());+
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    const int len = ops.count();+
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    Q_ASSERT(ops.count() > 1);+
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    Q_ASSERT(m_orderSpecs.count() == ops.count() - 1);+
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+
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    for(int i = 1; i < len; ++i)+
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        m_orderSpecs[i - 1].prepare(ops.at(i), context);+
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+
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    return me;+
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+
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    /* It's not meaningful to sort a single item or less, so rewrite ourselves+
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     * away if that is the case. This is an optimization. */+
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    /* TODO: How do we remove ReturnOrderBy?+
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    if(Cardinality::zeroOrOne().isMatch(m_operand->staticType()->cardinality()))+
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        return m_operand->typeCheck(context, reqType);+
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    else+
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        return SingleContainer::typeCheck(context, reqType);+
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     */+
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}+
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+
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Expression::Properties OrderBy::properties() const+
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{+
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    return m_operand->properties() & DisableElimination;+
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}+
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+
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Expression::Ptr OrderBy::compress(const StaticContext::Ptr &context)+
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{+
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    /* If we only will produce one item, there's no point in sorting. */+
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    if(m_operand->staticType()->cardinality().allowsMany())+
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        return SingleContainer::compress(context);+
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    else+
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    {+
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        m_returnOrderBy->setStay(false);+
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        return m_operand->compress(context);+
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    }+
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}+
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+
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SequenceType::Ptr OrderBy::staticType() const+
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{+
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    return m_operand->staticType();+
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}+
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+
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SequenceType::List OrderBy::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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    return result;+
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}+
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+
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ExpressionVisitorResult::Ptr+
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OrderBy::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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QT_END_NAMESPACE+
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