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#include "qcommonsequencetypes_p.h"

#include "qdynamiccontextstore_p.h"

#include "qevaluationcache_p.h"

#include "quserfunctioncallsite_p.h"

QT_BEGIN_NAMESPACE

using namespace QPatternist;

UserFunctionCallsite::UserFunctionCallsite(const QXmlName nameP,

                                           const FunctionSignature::Arity ar) : CallSite(nameP)

                                                                              , m_arity(ar)

                                                                              , m_expressionSlotOffset(-2)

{

}

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

{

    return m_body->evaluateSequence(bindVariables(context));

}

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

{

    return m_body->evaluateSingleton(bindVariables(context));

}

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

{

    return m_body->evaluateEBV(bindVariables(context));

}

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

{

    m_body->evaluateToSequenceReceiver(bindVariables(context));

}

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;

}

SequenceType::List UserFunctionCallsite::expectedOperandTypes() const

{

    SequenceType::List result;

    if(m_functionDeclaration)

    {

        const FunctionArgument::List args(m_functionDeclaration->signature()->arguments());

        const FunctionArgument::List::const_iterator end(args.constEnd());

        FunctionArgument::List::const_iterator it(args.constBegin());

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

            result.append((*it)->type());

    }

    else

        result.append(CommonSequenceTypes::ZeroOrMoreItems);

    return result;

}

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

                                                const SequenceType::Ptr &reqType)

{

    /* The parser calls TypeChecker::applyFunctionConversion() on user function

     * bodies, possibly indirectly, before all function call sites have been

     * resolved. Hence it's possible that we're called before before the usual

     * typeCheck() pass, and hence before we have been resolved/checked and

     * subsequently m_functionDeclaration set. Therefore, encounter for that below.

     *

     * UnresolvedVariableReference::typeCheck() has the same dilemma.

     */

    /* Ensure that the return value of the function is properly

     * converted/does match from where it is called(which is here). */

    if(isRecursive() || !m_functionDeclaration)

        return CallSite::typeCheck(context, reqType);

    else

    {

        /* Update, such that we use a recent version of the body that has typeCheck()

         * and compress() rewrites included. */

        m_body = m_functionDeclaration->body();

        /* Note, we can't assign to m_functionDeclaration->body() because UserFunction can apply

         * to several different callsites. Hence we need our own version. */

        m_body = m_body->typeCheck(context, reqType);

        /* We just act as a pipe for m_body, so we don't have to typecheck ourselves. However,

         * the arguments must match the function declaration. */

        typeCheckOperands(context);

        return Expression::Ptr(this);

    }

}

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

{

    if(!isRecursive())

        rewrite(m_body, m_body->compress(context), context);

    return CallSite::compress(context);

}

Expression::Properties UserFunctionCallsite::properties() const

{

    return DisableElimination;

}

SequenceType::Ptr UserFunctionCallsite::staticType() const

{

    /* Our return type, is the static type of the function body. We could have also used

     * m_functionDeclaration->signature()->returnType(), but it doesn't get updated

     * when function conversion is applied.

     * We can't use m_body's type if we're recursive, because m_body computes its type

     * from its children, and we're at least one of the children. Hence, we would

     * recurse infinitely if we did.

     *

     * m_body can be null here if we're called before setSource().

     */

    if(isRecursive() || !m_body)

        return CommonSequenceTypes::ZeroOrMoreItems; // TODO use the declaration, it can have a type explicitly.

    else

        return m_body->staticType();

}

ExpressionVisitorResult::Ptr UserFunctionCallsite::accept(const ExpressionVisitor::Ptr &visitor) const

{

    return visitor->visit(this);

}

Expression::ID UserFunctionCallsite::id() const

{

    return IDUserFunctionCallsite;

}

bool UserFunctionCallsite::isSignatureValid(const FunctionSignature::Ptr &sign) const

{

    Q_ASSERT(sign);

    return sign->name() == name()

           &&

           sign->isArityValid(m_arity);

}

bool UserFunctionCallsite::configureRecursion(const CallTargetDescription::Ptr &sign)

{

    Q_ASSERT(sign);

    setIsRecursive(isSignatureValid(sign));

    return isRecursive();

}

void UserFunctionCallsite::setSource(const UserFunction::Ptr &userFunction,

                                     const VariableSlotID cacheSlotOffset)

{

    m_functionDeclaration = userFunction;

    m_body = userFunction->body();

    m_expressionSlotOffset = userFunction->expressionSlotOffset();

    const int len = m_operands.size();

    const VariableDeclaration::List varDecls(userFunction->argumentDeclarations());

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

    {

        /* We don't want evaluation caches for range variables, it's not necessary since

         * the item is already cached in DynamicContext::rangeVariable(). */

        if(m_operands.at(i)->is(IDRangeVariableReference))

            continue;

        /* Note that we pass in cacheSlotOffset + i here instead of varDecls.at(i)->slot since

         * we want independent caches for each callsite. */

        m_operands[i] = Expression::Ptr(new EvaluationCache<false>(m_operands.at(i),

                                                                   varDecls.at(i),

                                                                   cacheSlotOffset + i));

    }

}

FunctionSignature::Arity UserFunctionCallsite::arity() const

{

    return m_arity;

}

CallTargetDescription::Ptr UserFunctionCallsite::callTargetDescription() const

{

    return m_functionDeclaration->signature();

}

QT_END_NAMESPACE