C++ PropertyDescriptor::setWritable方法代码示例

EncodedJSValue JSC_HOST_CALL objectConstructorFreeze(ExecState* exec)
{
    // 1. If Type(O) is not Object throw a TypeError exception.
    JSValue obj = exec->argument(0);
    if (!obj.isObject())
        return throwVMError(exec, createTypeError(exec, ASCIILiteral("Object.freeze can only be called on Objects.")));
    JSObject* object = asObject(obj);

    if (isJSFinalObject(object) && !hasIndexedProperties(object->structure()->indexingType())) {
        object->freeze(exec->vm());
        return JSValue::encode(obj);
    }

    // 2. For each named own property name P of O,
    PropertyNameArray properties(exec);
    object->methodTable()->getOwnPropertyNames(object, exec, properties, IncludeDontEnumProperties);
    PropertyNameArray::const_iterator end = properties.end();
    for (PropertyNameArray::const_iterator iter = properties.begin(); iter != end; ++iter) {
        // a. Let desc be the result of calling the [[GetOwnProperty]] internal method of O with P.
        PropertyDescriptor desc;
        if (!object->methodTable()->getOwnPropertyDescriptor(object, exec, *iter, desc))
            continue;
        // b. If IsDataDescriptor(desc) is true, then
        // i. If desc.[[Writable]] is true, set desc.[[Writable]] to false.
        if (desc.isDataDescriptor())
            desc.setWritable(false);
        // c. If desc.[[Configurable]] is true, set desc.[[Configurable]] to false.
        desc.setConfigurable(false);
        // d. Call the [[DefineOwnProperty]] internal method of O with P, desc, and true as arguments.
        object->methodTable()->defineOwnProperty(object, exec, *iter, desc, true);
        if (exec->hadException())
            return JSValue::encode(obj);
    }

    // 3. Set the [[Extensible]] internal property of O to false.
    object->preventExtensions(exec->vm());

    // 4. Return O.
    return JSValue::encode(obj);
}

// ES5 8.10.5 ToPropertyDescriptor
static bool toPropertyDescriptor(ExecState* exec, JSValue in, PropertyDescriptor& desc)
{
    if (!in.isObject()) {
        throwError(exec, createTypeError(exec, ASCIILiteral("Property description must be an object.")));
        return false;
    }
    JSObject* description = asObject(in);

    PropertySlot enumerableSlot(description);
    if (description->getPropertySlot(exec, exec->propertyNames().enumerable, enumerableSlot)) {
        desc.setEnumerable(enumerableSlot.getValue(exec, exec->propertyNames().enumerable).toBoolean(exec));
        if (exec->hadException())
            return false;
    }

    PropertySlot configurableSlot(description);
    if (description->getPropertySlot(exec, exec->propertyNames().configurable, configurableSlot)) {
        desc.setConfigurable(configurableSlot.getValue(exec, exec->propertyNames().configurable).toBoolean(exec));
        if (exec->hadException())
            return false;
    }

    JSValue value;
    PropertySlot valueSlot(description);
    if (description->getPropertySlot(exec, exec->propertyNames().value, valueSlot)) {
        desc.setValue(valueSlot.getValue(exec, exec->propertyNames().value));
        if (exec->hadException())
            return false;
    }

    PropertySlot writableSlot(description);
    if (description->getPropertySlot(exec, exec->propertyNames().writable, writableSlot)) {
        desc.setWritable(writableSlot.getValue(exec, exec->propertyNames().writable).toBoolean(exec));
        if (exec->hadException())
            return false;
    }

    PropertySlot getSlot(description);
    if (description->getPropertySlot(exec, exec->propertyNames().get, getSlot)) {
        JSValue get = getSlot.getValue(exec, exec->propertyNames().get);
        if (exec->hadException())
            return false;
        if (!get.isUndefined()) {
            CallData callData;
            if (getCallData(get, callData) == CallTypeNone) {
                throwError(exec, createTypeError(exec, ASCIILiteral("Getter must be a function.")));
                return false;
            }
        }
        desc.setGetter(get);
    }

    PropertySlot setSlot(description);
    if (description->getPropertySlot(exec, exec->propertyNames().set, setSlot)) {
        JSValue set = setSlot.getValue(exec, exec->propertyNames().set);
        if (exec->hadException())
            return false;
        if (!set.isUndefined()) {
            CallData callData;
            if (getCallData(set, callData) == CallTypeNone) {
                throwError(exec, createTypeError(exec, ASCIILiteral("Setter must be a function.")));
                return false;
            }
        }
        desc.setSetter(set);
    }

    if (!desc.isAccessorDescriptor())
        return true;

    if (desc.value()) {
        throwError(exec, createTypeError(exec, ASCIILiteral("Invalid property.  'value' present on property with getter or setter.")));
        return false;
    }

    if (desc.writablePresent()) {
        throwError(exec, createTypeError(exec, ASCIILiteral("Invalid property.  'writable' present on property with getter or setter.")));
        return false;
    }
    return true;
}