C++ Ptr::createStack方法代码示例

DynamicContext::Ptr UserFunctionCallsite::bindVariables(const DynamicContext::Ptr &context) const
{
    const DynamicContext::Ptr stackContext(context->createStack());
    Q_ASSERT(stackContext);

    const Expression::List::const_iterator end(m_operands.constEnd());
    Expression::List::const_iterator it(m_operands.constBegin());

    VariableSlotID slot = m_expressionSlotOffset;

    for(; it != end; ++it)
    {
        stackContext->setExpressionVariable(slot,
                                            Expression::Ptr(new DynamicContextStore(*it, context)));
        ++slot;
    }

    return stackContext;
}

DynamicContext::Ptr Template::createContext(const TemplateInvoker *const invoker,
                                            const DynamicContext::Ptr &context,
                                            const bool isCallTemplate) const
{
    Q_ASSERT(invoker);
    Q_ASSERT(context);

    /* We have:
     * - xsl:params in the target template (if any) which may provide
     *   default values.
     * - xsl:with-params in the caller (if any) which provides values.
     *
     * We need to, for each parameter:
     * - If the called template provides no default value and the caller
     *   has no value, it's an error
     * - If the called template has a default value and the caller provides
     *   none, it should be used
     * - In any case the caller provides a value, it needs to be used.
     *
     * Problems to look out for:
     *
     * - Each xsl:param is in scope for the subsequent xsl:params. Hence,
     *   the evaluation of one xsl:param can depend on another xsl:param,
     *   and so on
     * - The focus for xsl:params is different from the focus for
     *   the xsl:with-params
     * - The xsl:with-params are not in scope for the xsl:params.
     */

    WithParam::Hash withParams(invoker->withParams());

    /**
     * Parameters or not, we must in any case create a new stack frame
     * for the template invocation since otherwise we will trash our existing
     * variables. Hence it's as with calling user functions.
     *
     * This is especially reproducible with recursive functions.
     */
    DynamicContext::Ptr newStack(context->createStack());

    /* We have no parameters, and we have no further error checking to
     * do in the case of not being xsl:apply-templates, so we need to do nothing. */
    if(templateParameters.isEmpty() && (!isCallTemplate || withParams.isEmpty()))
        return newStack;

    const DynamicContext::TemplateParameterHash hashedParams(parametersAsHash());
    DynamicContext::TemplateParameterHash sewnTogether(hashedParams);

    const DynamicContext::TemplateParameterHash::iterator end(sewnTogether.end());

    for(DynamicContext::TemplateParameterHash::iterator it(sewnTogether.begin());
        it != end;
        ++it)
    {
        Expression::Ptr &param = it.value();

        WithParam::Ptr &withParam = withParams[it.key()];

        if(withParam)
            param = Expression::Ptr(new DynamicContextStore(withParam->sourceExpression(), context));
        else if(!param)
        {
            /* Ops, no xsl:with-param and no default value to cover up for it.
             */
            context->error(QtXmlPatterns::tr("The parameter %1 is required, but no corresponding %2 is supplied.")
                                             .arg(formatKeyword(context->namePool(), it.key()),
                                                  formatKeyword(QLatin1String("xsl:with-param"))),
                           ReportContext::XTSE0690,
                           this);
        }
    }

    if(isCallTemplate)
    {
        /* Find xsl:with-param that has no corresponding xsl:param. */
        /* Optimization: candidate for threading? */

        const WithParam::Hash::const_iterator end(withParams.constEnd());

        for(WithParam::Hash::const_iterator it(withParams.constBegin()); it != end; ++it)
        {
            if(!hashedParams.contains(it.key()))
                raiseXTSE0680(context, it.key(), this);
        }

    }

    newStack->templateParameterStore() = sewnTogether;
    return newStack;
}