C++ PropDesc::value方法代码示例

bool
js::GetElement(JSContext *cx, Handle<ObjectImpl*> obj, Handle<ObjectImpl*> receiver, uint32_t index,
               unsigned resolveFlags, Value *vp)
{
    NEW_OBJECT_REPRESENTATION_ONLY();

    Rooted<ObjectImpl*> current(cx, obj);

    RootedValue getter(cx);
    do {
        MOZ_ASSERT(current);

        if (Downcast(current)->isProxy()) {
            MOZ_NOT_REACHED("NYI: proxy [[GetP]]");
            return false;
        }

        PropDesc desc;
        if (!GetOwnElement(cx, current, index, resolveFlags, &desc))
            return false;

        /* No property?  Recur or bottom out. */
        if (desc.isUndefined()) {
            current = current->getProto();
            if (current)
                continue;

            vp->setUndefined();
            return true;
        }

        /* If it's a data property, return the value. */
        if (desc.isDataDescriptor()) {
            *vp = desc.value();
            return true;
        }

        /* If it's an accessor property, call its [[Get]] with the receiver. */
        if (desc.isAccessorDescriptor()) {
            getter = desc.getterValue();
            if (getter.isUndefined()) {
                vp->setUndefined();
                return true;
            }

            InvokeArgsGuard args;
            if (!cx->stack.pushInvokeArgs(cx, 0, &args))
                return false;

            /* Push getter, receiver, and no args. */
            args.setCallee(getter);
            args.setThis(ObjectValue(*current));

            bool ok = Invoke(cx, args);
            *vp = args.rval();
            return ok;
        }

        /* Otherwise it's a PropertyOp-based property.  XXX handle this! */
        MOZ_NOT_REACHED("NYI: handle PropertyOp'd properties here");
        return false;
    } while (false);

    MOZ_NOT_REACHED("buggy control flow");
    return false;
}

bool
DenseElementsHeader::defineElement(JSContext *cx, Handle<ObjectImpl*> obj, uint32_t index,
                                   const PropDesc &desc, bool shouldThrow, unsigned resolveFlags,
                                   bool *succeeded)
{
    MOZ_ASSERT(this == &obj->elementsHeader());

    MOZ_ASSERT_IF(desc.hasGet() || desc.hasSet(), !desc.hasValue() && !desc.hasWritable());
    MOZ_ASSERT_IF(desc.hasValue() || desc.hasWritable(), !desc.hasGet() && !desc.hasSet());

    /*
     * If desc is an accessor descriptor or a data descriptor with atypical
     * attributes, convert to sparse and retry.
     */
    if (desc.hasGet() || desc.hasSet() ||
        (desc.hasEnumerable() && !desc.enumerable()) ||
        (desc.hasConfigurable() && !desc.configurable()) ||
        (desc.hasWritable() && !desc.writable()))
    {
        if (!obj->makeElementsSparse(cx))
            return false;
        SparseElementsHeader &elts = obj->elementsHeader().asSparseElements();
        return elts.defineElement(cx, obj, index, desc, shouldThrow, resolveFlags, succeeded);
    }

    /* Does the element exist?  All behavior depends upon this. */
    uint32_t initLen = initializedLength();
    if (index < initLen) {
        HeapSlot &slot = obj->elements[index];
        if (!slot.isMagic(JS_ELEMENTS_HOLE)) {
            /*
             * The element exists with attributes { [[Enumerable]]: true,
             * [[Configurable]]: true, [[Writable]]: true, [[Value]]: slot }.
             */
            // XXX jwalden fill this in!
        }
    }

    /*
     * If the element doesn't exist, we can only add it if the object is
     * extensible.
     */
    if (!obj->isExtensible()) {
        *succeeded = false;
        if (!shouldThrow)
            return true;
        RootedValue val(cx, ObjectValue(*obj));
        MOZ_ALWAYS_FALSE(js_ReportValueErrorFlags(cx, JSREPORT_ERROR, JSMSG_OBJECT_NOT_EXTENSIBLE,
                                                  JSDVG_IGNORE_STACK,
                                                  val, NullPtr(),
                                                  NULL, NULL));
        return false;
    }

    /* Otherwise we ensure space for it exists and that it's initialized. */
    ObjectImpl::DenseElementsResult res = obj->ensureDenseElementsInitialized(cx, index, 0);

    /* Propagate any error. */
    if (res == ObjectImpl::Failure)
        return false;

    /* Otherwise, if the index was too far out of range, go sparse. */
    if (res == ObjectImpl::ConvertToSparse) {
        if (!obj->makeElementsSparse(cx))
            return false;
        SparseElementsHeader &elts = obj->elementsHeader().asSparseElements();
        return elts.defineElement(cx, obj, index, desc, shouldThrow, resolveFlags, succeeded);
    }

    /* But if we were able to ensure the element's existence, we're good. */
    MOZ_ASSERT(res == ObjectImpl::Succeeded);
    obj->elements[index].set(obj->asObjectPtr(), HeapSlot::Element, index, desc.value());
    *succeeded = true;
    return true;
}

bool
js::GetProperty(JSContext *cx, Handle<ObjectImpl*> obj, Handle<ObjectImpl*> receiver,
                Handle<PropertyId> pid, unsigned resolveFlags, MutableHandle<Value> vp)
{
    NEW_OBJECT_REPRESENTATION_ONLY();

    MOZ_ASSERT(receiver);

    Rooted<ObjectImpl*> current(cx, obj);

    do {
        MOZ_ASSERT(obj);

        if (Downcast(current)->isProxy()) {
            MOZ_NOT_REACHED("NYI: proxy [[GetP]]");
            return false;
        }

        PropDesc desc;
        PropDesc::AutoRooter rootDesc(cx, &desc);
        if (!GetOwnProperty(cx, current, pid, resolveFlags, &desc))
            return false;

        /* No property?  Recur or bottom out. */
        if (desc.isUndefined()) {
            current = current->getProto();
            if (current)
                continue;

            vp.setUndefined();
            return true;
        }

        /* If it's a data property, return the value. */
        if (desc.isDataDescriptor()) {
            vp.set(desc.value());
            return true;
        }

        /* If it's an accessor property, call its [[Get]] with the receiver. */
        if (desc.isAccessorDescriptor()) {
            Rooted<Value> get(cx, desc.getterValue());
            if (get.isUndefined()) {
                vp.setUndefined();
                return true;
            }

            InvokeArgsGuard args;
            if (!cx->stack.pushInvokeArgs(cx, 0, &args))
                return false;

            args.setCallee(get);
            args.setThis(ObjectValue(*receiver));

            bool ok = Invoke(cx, args);
            vp.set(args.rval());
            return ok;
        }

        /* Otherwise it's a PropertyOp-based property.  XXX handle this! */
        MOZ_NOT_REACHED("NYI: handle PropertyOp'd properties here");
        return false;
    } while (false);

    MOZ_NOT_REACHED("buggy control flow");
    return false;
}

bool
js::GetElement(JSContext *cx, ObjectImpl *obj, ObjectImpl *receiver, uint32_t index,
               Value *vp)
{
    NEW_OBJECT_REPRESENTATION_ONLY();

    do {
        MOZ_ASSERT(obj);

        if (static_cast<JSObject *>(obj)->isProxy()) { // XXX
            MOZ_NOT_REACHED("NYI: proxy [[GetP]]");
            return false;
        }

        PropDesc desc;
        if (!GetOwnElement(cx, obj, index, &desc))
            return false;

        /* No property?  Recur or bottom out. */
        if (desc.isUndefined()) {
            obj = obj->getProto();
            if (obj)
                continue;

            vp->setUndefined();
            return true;
        }

        /* If it's a data property, return the value. */
        if (desc.isDataDescriptor()) {
            *vp = desc.value();
            return true;
        }

        /* If it's an accessor property, call its [[Get]] with the receiver. */
        if (desc.isAccessorDescriptor()) {
            Value get = desc.getterValue();
            if (get.isUndefined()) {
                vp->setUndefined();
                return true;
            }

            InvokeArgsGuard args;
            if (!cx->stack.pushInvokeArgs(cx, 0, &args))
                return false;

            /* Push get, receiver, and no args. */
            args.calleev() = get;
            args.thisv() = ObjectValue(*receiver);

            bool ok = Invoke(cx, args);
            *vp = args.rval();
            return ok;
        }

        /* Otherwise it's a PropertyOp-based property.  XXX handle this! */
        MOZ_NOT_REACHED("NYI: handle PropertyOp'd properties here");
        return false;
    } while (false);

    MOZ_NOT_REACHED("buggy control flow");
    return false;
}