C++ Range::front方法代码示例

JS_GetPropertyDesc(JSContext *cx, JSObject *obj, JSScopeProperty *sprop,
                   JSPropertyDesc *pd)
{
    assertSameCompartment(cx, obj);
    Shape *shape = (Shape *) sprop;
    pd->id = IdToJsval(shape->propid());

    JSBool wasThrowing = cx->isExceptionPending();
    Value lastException = UndefinedValue();
    if (wasThrowing)
        lastException = cx->getPendingException();
    cx->clearPendingException();

    if (!js_GetProperty(cx, obj, shape->propid(), &pd->value)) {
        if (!cx->isExceptionPending()) {
            pd->flags = JSPD_ERROR;
            pd->value = JSVAL_VOID;
        } else {
            pd->flags = JSPD_EXCEPTION;
            pd->value = cx->getPendingException();
        }
    } else {
        pd->flags = 0;
    }

    if (wasThrowing)
        cx->setPendingException(lastException);

    pd->flags |= (shape->enumerable() ? JSPD_ENUMERATE : 0)
              |  (!shape->writable()  ? JSPD_READONLY  : 0)
              |  (!shape->configurable() ? JSPD_PERMANENT : 0);
    pd->spare = 0;
    if (shape->getter() == GetCallArg) {
        pd->slot = shape->shortid();
        pd->flags |= JSPD_ARGUMENT;
    } else if (shape->getter() == GetCallVar) {
        pd->slot = shape->shortid();
        pd->flags |= JSPD_VARIABLE;
    } else {
        pd->slot = 0;
    }
    pd->alias = JSVAL_VOID;

    if (obj->containsSlot(shape->slot())) {
        for (Shape::Range r = obj->lastProperty()->all(); !r.empty(); r.popFront()) {
            const Shape &aprop = r.front();
            if (&aprop != shape && aprop.slot() == shape->slot()) {
                pd->alias = IdToJsval(aprop.propid());
                break;
            }
        }
    }
    return JS_TRUE;
}

static bool
EnumerateNativeProperties(JSContext *cx, JSObject *obj, JSObject *pobj, uintN flags, IdSet &ht,
                          AutoIdVector *props)
{
    size_t initialLength = props->length();

    /* Collect all unique properties from this object's scope. */
    for (Shape::Range r = pobj->lastProperty()->all(); !r.empty(); r.popFront()) {
        const Shape &shape = r.front();

        if (!JSID_IS_DEFAULT_XML_NAMESPACE(shape.propid) &&
            !Enumerate(cx, obj, pobj, shape.propid, shape.enumerable(), flags, ht, props))
        {
            return false;
        }
    }

    ::Reverse(props->begin() + initialLength, props->end());
    return true;
}

JS_GetPropertyDescArray(JSContext *cx, JSObject *obj_, JSPropertyDescArray *pda)
{
    RootedObject obj(cx, obj_);

    assertSameCompartment(cx, obj);
    uint32_t i = 0;
    JSPropertyDesc *pd = NULL;

    if (obj->isDebugScope()) {
        AutoIdVector props(cx);
        if (!Proxy::enumerate(cx, obj, props))
            return false;

        pd = cx->pod_calloc<JSPropertyDesc>(props.length());
        if (!pd)
            return false;

        for (i = 0; i < props.length(); ++i) {
            pd[i].id = JSVAL_NULL;
            pd[i].value = JSVAL_NULL;
            if (!js_AddRoot(cx, &pd[i].id, NULL))
                goto bad;
            pd[i].id = IdToValue(props[i]);
            if (!js_AddRoot(cx, &pd[i].value, NULL))
                goto bad;
            if (!Proxy::get(cx, obj, obj, props.handleAt(i), MutableHandleValue::fromMarkedLocation(&pd[i].value)))
                goto bad;
        }

        pda->length = props.length();
        pda->array = pd;
        return true;
    }

    Class *clasp;
    clasp = obj->getClass();
    if (!obj->isNative() || (clasp->flags & JSCLASS_NEW_ENUMERATE)) {
        JS_ReportErrorNumber(cx, js_GetErrorMessage, NULL,
                             JSMSG_CANT_DESCRIBE_PROPS, clasp->name);
        return false;
    }
    if (!clasp->enumerate(cx, obj))
        return false;

    /* Return an empty pda early if obj has no own properties. */
    if (obj->nativeEmpty()) {
        pda->length = 0;
        pda->array = NULL;
        return true;
    }

    pd = cx->pod_malloc<JSPropertyDesc>(obj->propertyCount());
    if (!pd)
        return false;
    for (Shape::Range r = obj->lastProperty()->all(); !r.empty(); r.popFront()) {
        pd[i].id = JSVAL_NULL;
        pd[i].value = JSVAL_NULL;
        pd[i].alias = JSVAL_NULL;
        if (!js_AddRoot(cx, &pd[i].id, NULL))
            goto bad;
        if (!js_AddRoot(cx, &pd[i].value, NULL))
            goto bad;
        RootedShape shape(cx, const_cast<Shape *>(&r.front()));
        if (!GetPropertyDesc(cx, obj, shape, &pd[i]))
            goto bad;
        if ((pd[i].flags & JSPD_ALIAS) && !js_AddRoot(cx, &pd[i].alias, NULL))
            goto bad;
        if (++i == obj->propertyCount())
            break;
    }
    pda->length = i;
    pda->array = pd;
    return true;

bad:
    pda->length = i + 1;
    pda->array = pd;
    JS_PutPropertyDescArray(cx, pda);
    return false;
}

/*
 * Construct a call object for the given bindings.  If this is a call object
 * for a function invocation, callee should be the function being called.
 * Otherwise it must be a call object for eval of strict mode code, and callee
 * must be null.
 */
CallObject *
CallObject::create(JSContext *cx, JSScript *script, JSObject &enclosing, JSObject *callee)
{
    RootedVarShape shape(cx);
    shape = script->bindings.callObjectShape(cx);
    if (shape == NULL)
        return NULL;

    gc::AllocKind kind = gc::GetGCObjectKind(shape->numFixedSlots() + 1);

    RootedVarTypeObject type(cx);

    type = cx->compartment->getEmptyType(cx);
    if (!type)
        return NULL;

    HeapSlot *slots;
    if (!PreallocateObjectDynamicSlots(cx, shape, &slots))
        return NULL;

    JSObject *obj = JSObject::create(cx, kind, shape, type, slots);
    if (!obj)
        return NULL;

    /*
     * Update the parent for bindings associated with non-compileAndGo scripts,
     * whose call objects do not have a consistent global variable and need
     * to be updated dynamically.
     */
    JSObject &global = enclosing.global();
    if (&global != obj->getParent()) {
        JS_ASSERT(obj->getParent() == NULL);
        if (!obj->setParent(cx, &global))
            return NULL;
    }

#ifdef DEBUG
    JS_ASSERT(!obj->inDictionaryMode());
    for (Shape::Range r = obj->lastProperty(); !r.empty(); r.popFront()) {
        const Shape &s = r.front();
        if (s.hasSlot()) {
            JS_ASSERT(s.slot() + 1 == obj->slotSpan());
            break;
        }
    }
#endif

    if (!obj->asScope().setEnclosingScope(cx, enclosing))
        return NULL;

    JS_ASSERT_IF(callee, callee->isFunction());
    obj->initFixedSlot(CALLEE_SLOT, ObjectOrNullValue(callee));
    obj->initFixedSlot(ARGUMENTS_SLOT, MagicValue(JS_UNASSIGNED_ARGUMENTS));

    /*
     * If |bindings| is for a function that has extensible parents, that means
     * its Call should have its own shape; see BaseShape::extensibleParents.
     */
    if (obj->lastProperty()->extensibleParents() && !obj->generateOwnShape(cx))
        return NULL;

    return &obj->asCall();
}