C++ List::append方法代码示例

Item::Iterator::Ptr CardinalityVerifier::evaluateSequence(const DynamicContext::Ptr &context) const
{
    const Item::Iterator::Ptr it(m_operand->evaluateSequence(context));
    const Item next(it->next());

    if(next)
    {
        const Item next2(it->next());

        if(next2)
        {
            if(m_reqCard.allowsMany())
            {
                Item::List start;
                start.append(next);
                start.append(next2);

                return Item::Iterator::Ptr(new InsertionIterator(it, 1, makeListIterator(start)));
            }
            else
            {
                context->error(wrongCardinality(m_reqCard, Cardinality::twoOrMore()), m_errorCode, this);
                return CommonValues::emptyIterator;
            }
        }
        else
        {
            /* We might be instantiated for the empty sequence. */
            if(m_reqCard.isEmpty())
            {
                context->error(wrongCardinality(m_reqCard, Cardinality::twoOrMore()), m_errorCode, this);
                return CommonValues::emptyIterator;
            }
            else
                return makeSingletonIterator(next);
        }
    }
    else
    {
        if(m_reqCard.allowsEmpty())
            return CommonValues::emptyIterator;
        else
        {
            context->error(wrongCardinality(m_reqCard, Cardinality::twoOrMore()), m_errorCode, this);
            return CommonValues::emptyIterator;
        }
    }
}

Item::Iterator::Ptr Path::evaluateSequence(const DynamicContext::Ptr &context) const
{
    /* Note, we use the old context for m_operand1. */
    const Item::Iterator::Ptr source(m_operand1->evaluateSequence(context));

    const DynamicContext::Ptr focus(context->createFocus());
    focus->setFocusIterator(source);

    const Item::Iterator::Ptr result(makeSequenceMappingIterator<Item>(ConstPtr(this), source, focus));

    if(m_checkXPTY0018)
    {
        /* This is an expensive code path, but it should happen very rarely. */

        enum FoundItem
        {
            FoundNone,
            FoundNode,
            FoundAtomicValue
        } hasFound = FoundNone;

        Item::List whenChecked;

        Item next(result->next());

        while(next)
        {
            const FoundItem found = next.isAtomicValue() ? FoundAtomicValue : FoundNode;

            if(hasFound != FoundNone && hasFound != found)
            {
                /* It's an atomic value and we've already found a node. Mixed content. */
                context->error(QtXmlPatterns::tr("The last step in a path must contain either nodes "
                                                 "or atomic values. It cannot be a mixture between the two."),
                               ReportContext::XPTY0018, this);
            }
            else
                hasFound = found;

            whenChecked.append(next);
            next = result->next();
        }

        return makeListIterator(whenChecked);
    }
    else
        return result;
}

bool GeneralComparison::evaluateEBV(const DynamicContext::Ptr &context) const
{
    const Item::Iterator::Ptr it1(m_operand1->evaluateSequence(context));
    Item item1(it1->next());

    if(!item1)
        return false;

    const Item::Iterator::Ptr it2(m_operand2->evaluateSequence(context));
    Item::List cache;
    Item item2;

    while(true)
    {
        item2 = it2->next();
        if(!item2)
            break;

        if(generalCompare(item1, item2, context))
            return true;

        cache.append(item2);
    }

    while(true)
    {
        item1 = it1->next();

        if(!item1)
            return false;

        const Item::List::const_iterator end(cache.constEnd());
        Item::List::const_iterator it(cache.constBegin());

        for(; it != end; ++it)
            if(generalCompare(item1, *it, context))
                return true;
    }

    Q_ASSERT(false);
    return false;
}

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);
    }
}