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** This file is part of the QtXmlPatterns module of the Qt Toolkit.

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#include "qboolean_p.h"

#include "qcommonvalues_p.h"

#include "qemptysequence_p.h"

#include "qliteral_p.h"

#include "qliteralsequence_p.h"

#include "qoperandsiterator_p.h"

#include "qoptimizerframework_p.h"

#include "qstaticfocuscontext_p.h"

#include "qtypechecker_p.h"

#include "qexpression_p.h"

QT_BEGIN_NAMESPACE

using namespace QPatternist;

Expression::~Expression()

{

}

StaticContext::Ptr Expression::finalizeStaticContext(const StaticContext::Ptr &context) const

{

    Q_ASSERT(context);

    const ItemType::Ptr focusType(newFocusType());

    Q_ASSERT(focusType);

    return StaticContext::Ptr(new StaticFocusContext(focusType, context));

}

Expression::Ptr Expression::typeCheck(const StaticContext::Ptr &context,

                                      const SequenceType::Ptr &reqType)

{

    Q_ASSERT(reqType);

    typeCheckOperands(context);

    return TypeChecker::applyFunctionConversion(Expression::Ptr(this), reqType, context);

}

void Expression::typeCheckOperands(const StaticContext::Ptr &context)

{

    const Expression::List ops(operands());

    /* Check if this expression has any operands at all. */

    if(ops.isEmpty())

        return; /* We're done, early exit. */

    const SequenceType::List opTypes(expectedOperandTypes());

    Expression::List result;

    /* If we create a focus, we handle the last one specially, so avoid it in the loop. */

    const bool createsFocus = has(CreatesFocusForLast);

    const SequenceType::List::const_iterator typeEnd(createsFocus ? --opTypes.constEnd()

                                                                  : opTypes.constEnd());

    const Expression::List::const_iterator end(createsFocus ? --ops.constEnd()

                                                            : ops.constEnd());

    SequenceType::List::const_iterator reqType(opTypes.constBegin());

    SequenceType::Ptr t(*reqType);

    // TODO we assign twice to t here(also below in loop) when ops.size() > 1

    Expression::List::const_iterator it(ops.constBegin());

    for(; it != end; ++it)

    {

        /* This ensures that the last expectedOperandType stays, and is

         * used for all other operands. This is used for expressions that

         * have an infinite amount of operands, such as the concat() function. */

        if(reqType != typeEnd)

        {

            t = *reqType;

            ++reqType;

        }

         /* Let the child & its children typecheck. */

        result.append((*it)->typeCheck(context, t));

    }

    if(createsFocus)

    {

        const StaticContext::Ptr newContext(finalizeStaticContext(context));

        result.append(ops.last()->typeCheck(newContext, opTypes.last()));

    }

    setOperands(result);

}

Expression::Ptr Expression::invokeOptimizers(const Expression::Ptr &expr,

                                             const StaticContext::Ptr &context)

{

    Q_ASSERT(expr);

    const OptimizationPass::List opts(expr->optimizationPasses());

    if(opts.isEmpty()) /* Early exit. */

    {

        return expr;

    }

    const OptimizationPass::List::const_iterator passEnd(opts.constEnd());

    const OptimizationPass::List::const_iterator end(opts.constEnd());

    OptimizationPass::List::const_iterator passIt(opts.constBegin());

    for(; passIt != passEnd; ++passIt) /* Invoke each optimization pass. */

    {

        const OptimizationPass::Ptr pass(*passIt); /* Alias, for readability. */

        OptimizationPass::ExpressionMarker sourceMarker(pass->sourceExpression);

        if(pass->startIdentifier && !pass->startIdentifier->matches(expr))

        {

            /* This pass specified a start identifier and it did

             * not match -- let's try the next OptimizationPass. */

            continue;

        }

        const ExpressionIdentifier::List::const_iterator idEnd(pass->operandIdentifiers.constEnd());

        ExpressionIdentifier::List::const_iterator idIt(pass->operandIdentifiers.constBegin());

        const Expression::List ops(expr->operands());

        const Expression::List::const_iterator opEnd(ops.constEnd());

        Expression::List::const_iterator opIt(ops.constBegin());

        switch(pass->operandsMatchMethod)

        {

            case OptimizationPass::Sequential:

            {

                for(; opIt != opEnd; ++opIt)

                {

                    const Expression::Ptr operand(*opIt); /* Alias, for readability. */

                    const ExpressionIdentifier::Ptr opIdentifier(*idIt); /* Alias, for readability. */

                    if(opIdentifier && !opIdentifier->matches(operand))

                    {

                        break;

                    }

                    ++idIt;

                }

                if(opIt == opEnd)

                    break; /* All operands matched, so this pass matched. */

                else

                {

                    /* The loop above did not finish which means all operands did not match.

                       Therefore, this OptimizationPass did not match -- let's try the next one. */

                    continue;

                }

            }

            case OptimizationPass::AnyOrder:

            {

                Q_ASSERT_X(ops.count() == 2, Q_FUNC_INFO,

                           "AnyOrder is currently only supported for Expressions with two operands.");

                if(pass->operandIdentifiers.first()->matches(ops.first()) &&

                   pass->operandIdentifiers.last()->matches(ops.last()))

                {

                    break;

                }

                else if(pass->operandIdentifiers.first()->matches(ops.last()) &&

                        pass->operandIdentifiers.last()->matches(ops.first()))

                {

                    sourceMarker.first() = 1;

                    sourceMarker[1] = 0;

                    break; /* This pass matched. */

                }

                else

                    continue; /* This pass didn't match, let's loop through the next pass. */

            }

        }

        /* Figure out the source Expression, if any. */

        Expression::List operands;

        Expression::Ptr sourceExpr;

        if(!sourceMarker.isEmpty())

        {

            const OptimizationPass::ExpressionMarker::const_iterator mEnd(sourceMarker.constEnd());

            OptimizationPass::ExpressionMarker::const_iterator mIt(sourceMarker.constBegin());

            sourceExpr = expr;

            for(; mIt != mEnd; ++mIt)

            {

                Q_ASSERT(*mIt >= 0);

                sourceExpr = sourceExpr->operands().at(*mIt);

            }

            operands.append(sourceExpr);

        }

        if(operands.isEmpty())

        {

            Q_ASSERT(pass->resultCreator);

            return pass->resultCreator->create(Expression::List(), context, expr.data())->compress(context);

        }

        else if(pass->resultCreator)

            return pass->resultCreator->create(operands, context, expr.data())->compress(context);

        else

        {

            return sourceExpr;

        }

    }

    return expr;

}

Expression::Ptr Expression::compress(const StaticContext::Ptr &context)

{

    if(!compressOperands(context))

    {

        /* At least one of the operands cannot be evaluated at compile, so

         * 'this' Expression cannot const fold. */

        return invokeOptimizers(Expression::Ptr(this), context);

    }

    Expression::Ptr retval;

    if(hasDependency(DisableElimination))

        retval = Expression::Ptr(this);

    else

        retval = constantPropagate(context);

    return invokeOptimizers(retval, context);

}

Expression::Ptr Expression::constantPropagate(const StaticContext::Ptr &context) const

{

    Q_ASSERT(context);

    /* Optimization: We rewrite literals to literals here, which is pointless.

     * Maybe we should have a property which says "doesn't disable elimination

     * but don't eliminate me." */

    if(staticType()->cardinality().allowsMany())

    {

        Item::Iterator::Ptr it(evaluateSequence(context->dynamicContext()));

        Item::List result;

        Item item(it->next());

        while(item)

        {

            result.append(item);

            item = it->next();

        }

        switch(result.count())

        {

            case 0:

                return EmptySequence::create(this, context);

            case 1:

                return rewrite(Expression::Ptr(new Literal(result.first())), context);

            default:

                return rewrite(Expression::Ptr(new LiteralSequence(result)), context);

        }

    }

    else

    {

        const Item item(evaluateSingleton(context->dynamicContext()));

        if(item)

            return rewrite(Expression::Ptr(new Literal(item)), context);

        else

            return EmptySequence::create(this, context);

    }

}

Item::Iterator::Ptr Expression::evaluateSequence(const DynamicContext::Ptr &context) const

{

    const Item item(evaluateSingleton(context));

    if(item)

        return makeSingletonIterator(item);

    else

        return CommonValues::emptyIterator;

}

Item Expression::evaluateSingleton(const DynamicContext::Ptr &context) const

{

    return Boolean::fromValue(evaluateEBV(context));

}

bool Expression::evaluateEBV(const DynamicContext::Ptr &context) const

{

    return Boolean::evaluateEBV(evaluateSequence(context), context);

}

void Expression::evaluateToSequenceReceiver(const DynamicContext::Ptr &context) const

{

    QAbstractXmlReceiver *const receiver = context->outputReceiver();

    const Item::Iterator::Ptr it(evaluateSequence(context));

    Item next(it->next());

    while(next)

    {

        receiver->item(next);

        next = it->next();

    }

}

ItemType::Ptr Expression::expectedContextItemType() const

{

    Q_ASSERT_X(false, Q_FUNC_INFO,

               "expectedContextItemType() must be overridden when RequiresContextItem is set.");

    return ItemType::Ptr();

}

Expression::Properties Expression::properties() const

{

    return Properties();

}

Expression::Properties Expression::dependencies() const

{

    OperandsIterator it(Ptr(const_cast<Expression *>(this)), OperandsIterator::ExcludeParent);

    Expression::Ptr next(it.next());

    Properties dependencies(properties());

    while(next)

    {

        dependencies |= next->dependencies();

        next = it.next();

    }

    return dependencies & (Expression::RequiresFocus | Expression::IsEvaluated | Expression::DisableElimination);

}

void Expression::announceFocusType(const ItemType::Ptr &itemType)

{

    const Expression::List ops(operands());

    const int len = ops.count();

    for(int i = 0; i < len; ++i)

        ops.at(i)->announceFocusType(itemType);

}

Expression::Properties Expression::deepProperties() const

{

    Properties props(properties());

    const Expression::List ops(operands());

    const int len = ops.count();

    for(int i = 0; i < len; ++i)

        props |= ops.at(i)->deepProperties();

    return props;

}

Expression::ID Expression::id() const

{

    return IDIgnorableExpression;

}

OptimizationPass::List Expression::optimizationPasses() const

{

    return OptimizationPass::List();

}

ItemType::Ptr Expression::newFocusType() const

{

    Q_ASSERT_X(false, Q_FUNC_INFO,

               "This function must be overridden when CreatesFocusForLast is set.");

    return ItemType::Ptr();

}

const SourceLocationReflection *Expression::actualReflection() const

{

    return this;

}

QString Expression::description() const

{

    return QString::fromLatin1("Expression, id: %1").arg(QString::number(id()));

}

PatternPriority Expression::patternPriority() const

{

    return 0.5;

}

QT_END_NAMESPACE