C++ JSFunction::preventExtensions方法代码示例

//.........这里部分代码省略.........
    jsid objectId = ATOM_TO_JSID(CLASS_ATOM(cx, Object));
    JSFunction *objectCtor;
    {
        JSObject *ctor = NewObjectWithGivenProto(cx, &FunctionClass, functionProto, this);
        if (!ctor)
            return NULL;
        objectCtor = js_NewFunction(cx, ctor, js_Object, 1, JSFUN_CONSTRUCTOR, this,
                                    JSID_TO_ATOM(objectId));
        if (!objectCtor)
            return NULL;
        JS_ASSERT(ctor == objectCtor);

        objectCtor->setConstructorClass(&ObjectClass);
    }

    /*
     * Install |Object| and |Object.prototype| for the benefit of subsequent
     * code that looks for them.
     */
    setObjectClassDetails(objectCtor, objectProto);

    /* Create |Function| so it and |Function.prototype| can be installed. */
    jsid functionId = ATOM_TO_JSID(CLASS_ATOM(cx, Function));
    JSFunction *functionCtor;
    {
        JSObject *ctor =
            NewObjectWithGivenProto(cx, &FunctionClass, functionProto, this);
        if (!ctor)
            return NULL;
        functionCtor = js_NewFunction(cx, ctor, Function, 1, JSFUN_CONSTRUCTOR, this,
                                      JSID_TO_ATOM(functionId));
        if (!functionCtor)
            return NULL;
        JS_ASSERT(ctor == functionCtor);

        functionCtor->setConstructorClass(&FunctionClass);
    }

    /*
     * Install |Function| and |Function.prototype| so that we can freely create
     * functions and objects without special effort.
     */
    setFunctionClassDetails(functionCtor, functionProto);

    /*
     * The hard part's done: now go back and add all the properties these
     * primordial values have.
     */
    if (!LinkConstructorAndPrototype(cx, objectCtor, objectProto) ||
        !DefinePropertiesAndBrand(cx, objectProto, object_props, object_methods) ||
        !DefinePropertiesAndBrand(cx, objectCtor, NULL, object_static_methods) ||
        !LinkConstructorAndPrototype(cx, functionCtor, functionProto) ||
        !DefinePropertiesAndBrand(cx, functionProto, NULL, function_methods) ||
        !DefinePropertiesAndBrand(cx, functionCtor, NULL, NULL))
    {
        return NULL;
    }

    /* Add the global Function and Object properties now. */
    if (!addDataProperty(cx, objectId, JSProto_Object + JSProto_LIMIT * 2, 0))
        return NULL;
    if (!addDataProperty(cx, functionId, JSProto_Function + JSProto_LIMIT * 2, 0))
        return NULL;

    /* Heavy lifting done, but lingering tasks remain. */

    /* ES5 15.1.2.1. */
    jsid id = ATOM_TO_JSID(cx->runtime->atomState.evalAtom);
    JSObject *evalobj = js_DefineFunction(cx, this, id, eval, 1, JSFUN_STUB_GSOPS);
    if (!evalobj)
        return NULL;
    setOriginalEval(evalobj);

    /* ES5 13.2.3: Construct the unique [[ThrowTypeError]] function object. */
    JSFunction *throwTypeError = js_NewFunction(cx, NULL, ThrowTypeError, 0, 0, this, NULL);
    if (!throwTypeError)
        return NULL;
    AutoIdVector ids(cx);
    if (!throwTypeError->preventExtensions(cx, &ids))
        return NULL;
    setThrowTypeError(throwTypeError);

    /*
     * The global object should have |Object.prototype| as its [[Prototype]].
     * Eventually we'd like to have standard classes be there from the start,
     * and thus we would know we were always setting what had previously been a
     * null [[Prototype]], but right now some code assumes it can set the
     * [[Prototype]] before standard classes have been initialized.  For now,
     * only set the [[Prototype]] if it hasn't already been set.
     */
    if (shouldSplicePrototype(cx) && !splicePrototype(cx, objectProto))
        return NULL;

    /*
     * Notify any debuggers about the creation of the script for
     * |Function.prototype| -- after all initialization, for simplicity.
     */
    js_CallNewScriptHook(cx, functionProto->script(), functionProto);
    return functionProto;
}