C++ PropertyDescriptor类代码示例

bool Arguments::getOwnPropertyDescriptor(ExecState* exec, const Identifier& propertyName, PropertyDescriptor& descriptor)
{
    bool isArrayIndex;
    unsigned i = propertyName.toArrayIndex(isArrayIndex);
    if (isArrayIndex && i < d->numArguments && (!d->deletedArguments || !d->deletedArguments[i])) {
        if (i < d->numParameters) {
            descriptor.setDescriptor(d->registers[d->firstParameterIndex + i].get(), None);
        } else
            descriptor.setDescriptor(d->extraArguments[i - d->numParameters].get(), None);
        return true;
    }
    
    if (propertyName == exec->propertyNames().length && LIKELY(!d->overrodeLength)) {
        descriptor.setDescriptor(jsNumber(d->numArguments), DontEnum);
        return true;
    }
    
    if (propertyName == exec->propertyNames().callee && LIKELY(!d->overrodeCallee)) {
        if (!d->isStrictMode) {
            descriptor.setDescriptor(d->callee.get(), DontEnum);
            return true;
        }
        createStrictModeCalleeIfNecessary(exec);
    }

    if (propertyName == exec->propertyNames().caller && d->isStrictMode)
        createStrictModeCallerIfNecessary(exec);
    
    return JSObject::getOwnPropertyDescriptor(exec, propertyName, descriptor);
}

 bool AJFunction::getOwnPropertyDescriptor(ExecState* exec, const Identifier& propertyName, PropertyDescriptor& descriptor)
 {
     if (isHostFunction())
         return Base::getOwnPropertyDescriptor(exec, propertyName, descriptor);
     
     if (propertyName == exec->propertyNames().prototype) {
         PropertySlot slot;
         getOwnPropertySlot(exec, propertyName, slot);
         return Base::getOwnPropertyDescriptor(exec, propertyName, descriptor);
     }
     
     if (propertyName == exec->propertyNames().arguments) {
         descriptor.setDescriptor(exec->interpreter()->retrieveArguments(exec, this), ReadOnly | DontEnum | DontDelete);
         return true;
     }
     
     if (propertyName == exec->propertyNames().length) {
         descriptor.setDescriptor(jsNumber(exec, jsExecutable()->parameterCount()), ReadOnly | DontEnum | DontDelete);
         return true;
     }
     
     if (propertyName == exec->propertyNames().caller) {
         descriptor.setDescriptor(exec->interpreter()->retrieveCaller(exec, this), ReadOnly | DontEnum | DontDelete);
         return true;
     }
     
     return Base::getOwnPropertyDescriptor(exec, propertyName, descriptor);
 }

bool JSArray::getOwnPropertyDescriptor(ExecState* exec, const Identifier& propertyName, PropertyDescriptor& descriptor)
{
    if (propertyName == exec->propertyNames().length) {
        descriptor.setDescriptor(jsNumber(exec, length()), DontDelete | DontEnum);
        return true;
    }
    
    bool isArrayIndex;
    unsigned i = propertyName.toArrayIndex(&isArrayIndex);
    if (isArrayIndex) {
        if (i >= m_storage->m_length)
            return false;
        if (i < m_vectorLength) {
            JSValue& value = m_storage->m_vector[i];
            if (value) {
                descriptor.setDescriptor(value, 0);
                return true;
            }
        } else if (SparseArrayValueMap* map = m_storage->m_sparseValueMap) {
            if (i >= MIN_SPARSE_ARRAY_INDEX) {
                SparseArrayValueMap::iterator it = map->find(i);
                if (it != map->end()) {
                    descriptor.setDescriptor(it->second, 0);
                    return true;
                }
            }
        }
    }
    return JSObject::getOwnPropertyDescriptor(exec, propertyName, descriptor);
}

EncodedJSValue JSC_HOST_CALL objectConstructorIsFrozen(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.isFrozen can only be called on Objects.")));
    JSObject* object = asObject(obj);

    if (isJSFinalObject(object))
        return JSValue::encode(jsBoolean(object->isFrozen(exec->vm())));

    // 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, return false. c. If desc.[[Configurable]] is true, then return false.
        if ((desc.isDataDescriptor() && desc.writable()) || desc.configurable())
            return JSValue::encode(jsBoolean(false));
    }

    // 3. If the [[Extensible]] internal property of O is false, then return true.
    // 4. Otherwise, return false.
    return JSValue::encode(jsBoolean(!object->isExtensible()));
}

bool JSNPObject::getOwnPropertyDescriptor(JSObject* object, ExecState* exec, PropertyName propertyName, PropertyDescriptor& descriptor)
{
    JSNPObject* thisObject = jsCast<JSNPObject*>(object);
    ASSERT_GC_OBJECT_INHERITS(thisObject, &s_info);
    if (!thisObject->m_npObject) {
        throwInvalidAccessError(exec);
        return false;
    }

    NPIdentifier npIdentifier = npIdentifierFromIdentifier(propertyName);

    // Calling NPClass::invoke will call into plug-in code, and there's no telling what the plug-in can do.
    // (including destroying the plug-in). Because of this, we make sure to keep the plug-in alive until 
    // the call has finished.
    NPRuntimeObjectMap::PluginProtector protector(thisObject->m_objectMap);

    // First, check if the NPObject has a property with this name.
    if (thisObject->m_npObject->_class->hasProperty && thisObject->m_npObject->_class->hasProperty(thisObject->m_npObject, npIdentifier)) {
        PropertySlot slot;
        slot.setCustom(thisObject, propertyGetter);
        descriptor.setDescriptor(slot.getValue(exec, propertyName), DontDelete);
        return true;
    }

    // Second, check if the NPObject has a method with this name.
    if (thisObject->m_npObject->_class->hasMethod && thisObject->m_npObject->_class->hasMethod(thisObject->m_npObject, npIdentifier)) {
        PropertySlot slot;
        slot.setCustom(thisObject, methodGetter);
        descriptor.setDescriptor(slot.getValue(exec, propertyName), DontDelete | ReadOnly);
        return true;
    }

    return false;
}

// https://tc39.github.io/ecma262/#sec-reflect.defineproperty
EncodedJSValue JSC_HOST_CALL reflectObjectDefineProperty(ExecState* exec)
{
    VM& vm = exec->vm();
    auto scope = DECLARE_THROW_SCOPE(vm);

    JSValue target = exec->argument(0);
    if (!target.isObject())
        return JSValue::encode(throwTypeError(exec, scope, ASCIILiteral("Reflect.defineProperty requires the first argument be an object")));
    auto propertyName = exec->argument(1).toPropertyKey(exec);
    RETURN_IF_EXCEPTION(scope, encodedJSValue());

    PropertyDescriptor descriptor;
    bool success = toPropertyDescriptor(exec, exec->argument(2), descriptor);
    ASSERT(!scope.exception() == success);
    if (UNLIKELY(!success))
        return encodedJSValue();
    ASSERT((descriptor.attributes() & Accessor) || (!descriptor.isAccessorDescriptor()));
    ASSERT(!scope.exception());

    // Reflect.defineProperty should not throw an error when the defineOwnProperty operation fails.
    bool shouldThrow = false;
    JSObject* targetObject = asObject(target);
    scope.release();
    return JSValue::encode(jsBoolean(targetObject->methodTable(vm)->defineOwnProperty(targetObject, exec, propertyName, descriptor, shouldThrow)));
}

EncodedJSValue JSC_HOST_CALL objectConstructorGetOwnPropertyDescriptor(ExecState* exec)
{
    if (!exec->argument(0).isObject())
        return throwVMError(exec, createTypeError(exec, ASCIILiteral("Requested property descriptor of a value that is not an object.")));
    String propertyName = exec->argument(1).toString(exec)->value(exec);
    if (exec->hadException())
        return JSValue::encode(jsNull());
    JSObject* object = asObject(exec->argument(0));
    PropertyDescriptor descriptor;
    if (!object->methodTable()->getOwnPropertyDescriptor(object, exec, Identifier(exec, propertyName), descriptor))
        return JSValue::encode(jsUndefined());
    if (exec->hadException())
        return JSValue::encode(jsUndefined());

    JSObject* description = constructEmptyObject(exec);
    if (!descriptor.isAccessorDescriptor()) {
        description->putDirect(exec->vm(), exec->propertyNames().value, descriptor.value() ? descriptor.value() : jsUndefined(), 0);
        description->putDirect(exec->vm(), exec->propertyNames().writable, jsBoolean(descriptor.writable()), 0);
    } else {
        ASSERT(descriptor.getter());
        ASSERT(descriptor.setter());
        description->putDirect(exec->vm(), exec->propertyNames().get, descriptor.getter(), 0);
        description->putDirect(exec->vm(), exec->propertyNames().set, descriptor.setter(), 0);
    }

    description->putDirect(exec->vm(), exec->propertyNames().enumerable, jsBoolean(descriptor.enumerable()), 0);
    description->putDirect(exec->vm(), exec->propertyNames().configurable, jsBoolean(descriptor.configurable()), 0);

    return JSValue::encode(description);
}

bool JSNamedNodeMap::getOwnPropertyDescriptor(ExecState* exec, const Identifier& propertyName, PropertyDescriptor& descriptor)
{
    ASSERT_GC_OBJECT_INHERITS(this, &s_info);
    JSValue proto = prototype();
    if (proto.isObject() && static_cast<JSObject*>(asObject(proto))->hasProperty(exec, propertyName))
        return false;

    const HashEntry* entry = JSNamedNodeMapTable.entry(exec, propertyName);
    if (entry) {
        PropertySlot slot;
        slot.setCustom(this, entry->propertyGetter());
        descriptor.setDescriptor(slot.getValue(exec, propertyName), entry->attributes());
        return true;
    }
    bool ok;
    unsigned index = propertyName.toUInt32(ok);
    if (ok && index < static_cast<NamedNodeMap*>(impl())->length()) {
        PropertySlot slot;
        slot.setCustomIndex(this, index, indexGetter);
        descriptor.setDescriptor(slot.getValue(exec, propertyName), DontDelete | ReadOnly);
        return true;
    }
    if (canGetItemsForName(exec, static_cast<NamedNodeMap*>(impl()), propertyName)) {
        PropertySlot slot;
        slot.setCustom(this, nameGetter);
        descriptor.setDescriptor(slot.getValue(exec, propertyName), ReadOnly | DontDelete | DontEnum);
        return true;
    }
    return getStaticValueDescriptor<JSNamedNodeMap, Base>(exec, &JSNamedNodeMapTable, this, propertyName, descriptor);
}

bool Arguments::getOwnPropertyDescriptor(JSObject* object, ExecState* exec, PropertyName propertyName, PropertyDescriptor& descriptor)
{
    Arguments* thisObject = jsCast<Arguments*>(object);
    unsigned i = propertyName.asIndex();
    if (i < thisObject->d->numArguments && (!thisObject->d->deletedArguments || !thisObject->d->deletedArguments[i])) {
        ASSERT(i < PropertyName::NotAnIndex);
        descriptor.setDescriptor(thisObject->argument(i).get(), None);
        return true;
    }
    
    if (propertyName == exec->propertyNames().length && LIKELY(!thisObject->d->overrodeLength)) {
        descriptor.setDescriptor(jsNumber(thisObject->d->numArguments), DontEnum);
        return true;
    }
    
    if (propertyName == exec->propertyNames().callee && LIKELY(!thisObject->d->overrodeCallee)) {
        if (!thisObject->d->isStrictMode) {
            descriptor.setDescriptor(thisObject->d->callee.get(), DontEnum);
            return true;
        }
        thisObject->createStrictModeCalleeIfNecessary(exec);
    }

    if (propertyName == exec->propertyNames().caller && thisObject->d->isStrictMode)
        thisObject->createStrictModeCallerIfNecessary(exec);
    
    return JSObject::getOwnPropertyDescriptor(thisObject, exec, propertyName, descriptor);
}

bool JSObject::propertyIsEnumerable(ExecState* exec, const Identifier& propertyName) const
{
    PropertyDescriptor descriptor;
    if (!const_cast<JSObject*>(this)->getOwnPropertyDescriptor(exec, propertyName, descriptor))
        return false;
    return descriptor.enumerable();
}

void BaseEntity::SerializeProperties(IPropertyContainer *container, SerializableNodeObject *parent)
{
    int count = container->GetNumProperties();
    auto props = container->GetProperties();

    SerializableNodeArray* nPropContainer = new SerializableNodeArray("properties");

    for (int i = 0; i < count; ++i)
    {
        auto p = props[i];
        PropertyDescriptor* desc = p->GetDescriptor();

        if (desc->CanSerialize)
        {
            auto propObject = new SerializableNodeObject();

            desc->Serialize(propObject);

            propObject->AddChild(new SerializableProperty("Value", p->GetString().c_str()));

            nPropContainer->AddChild(propObject);
        }
    }

    parent->AddChild(nPropContainer);
}

EncodedJSValue JSC_HOST_CALL objectProtoFuncDefineSetter(ExecState* exec)
{
    JSObject* thisObject = exec->thisValue().toThis(exec, StrictMode).toObject(exec);
    if (exec->hadException())
        return JSValue::encode(jsUndefined());

    JSValue set = exec->argument(1);
    CallData callData;
    if (getCallData(set, callData) == CallTypeNone)
        return throwVMError(exec, createTypeError(exec, ASCIILiteral("invalid setter usage")));

    auto propertyName = exec->argument(0).toPropertyKey(exec);
    if (exec->hadException())
        return JSValue::encode(jsUndefined());

    PropertyDescriptor descriptor;
    descriptor.setSetter(set);
    descriptor.setEnumerable(true);
    descriptor.setConfigurable(true);

    bool shouldThrow = false;
    thisObject->methodTable(exec->vm())->defineOwnProperty(thisObject, exec, propertyName, descriptor, shouldThrow);

    return JSValue::encode(jsUndefined());
}

bool JSCSSStyleDeclaration::getOwnPropertyDescriptor(ExecState* exec, const Identifier& propertyName, PropertyDescriptor& descriptor)
{
    ASSERT_GC_OBJECT_INHERITS(this, &s_info);
    const HashEntry* entry = JSCSSStyleDeclarationTable.entry(exec, propertyName);
    if (entry) {
        PropertySlot slot;
        slot.setCustom(this, entry->propertyGetter());
        descriptor.setDescriptor(slot.getValue(exec, propertyName), entry->attributes());
        return true;
    }
    bool ok;
    unsigned index = propertyName.toUInt32(ok);
    if (ok && index < static_cast<CSSStyleDeclaration*>(impl())->length()) {
        PropertySlot slot;
        slot.setCustomIndex(this, index, indexGetter);
        descriptor.setDescriptor(slot.getValue(exec, propertyName), DontDelete | ReadOnly);
        return true;
    }
    if (canGetItemsForName(exec, static_cast<CSSStyleDeclaration*>(impl()), propertyName)) {
        PropertySlot slot;
        slot.setCustom(this, nameGetter);
        descriptor.setDescriptor(slot.getValue(exec, propertyName), ReadOnly | DontDelete | DontEnum);
        return true;
    }
    return getStaticValueDescriptor<JSCSSStyleDeclaration, Base>(exec, &JSCSSStyleDeclarationTable, this, propertyName, descriptor);
}

void Arguments::createStrictModeCalleeIfNecessary(ExecState* exec)
{
    if (d->overrodeCallee)
        return;
    
    d->overrodeCallee = true;
    PropertyDescriptor descriptor;
    descriptor.setAccessorDescriptor(globalObject()->throwTypeErrorGetterSetter(exec), DontEnum | DontDelete | Accessor);
    methodTable()->defineOwnProperty(this, exec, exec->propertyNames().callee, descriptor, false);
}

static JSValue defineProperties(ExecState* exec, JSObject* object, JSObject* properties)
{
    PropertyNameArray propertyNames(exec);
    asObject(properties)->methodTable()->getOwnPropertyNames(asObject(properties), exec, propertyNames, ExcludeDontEnumProperties);
    size_t numProperties = propertyNames.size();
    Vector<PropertyDescriptor> descriptors;
    MarkedArgumentBuffer markBuffer;
    for (size_t i = 0; i < numProperties; i++) {
        PropertySlot slot;
        JSValue prop = properties->get(exec, propertyNames[i]);
        if (exec->hadException())
            return jsNull();
        PropertyDescriptor descriptor;
        if (!toPropertyDescriptor(exec, prop, descriptor))
            return jsNull();
        descriptors.append(descriptor);
        // Ensure we mark all the values that we're accumulating
        if (descriptor.isDataDescriptor() && descriptor.value())
            markBuffer.append(descriptor.value());
        if (descriptor.isAccessorDescriptor()) {
            if (descriptor.getter())
                markBuffer.append(descriptor.getter());
            if (descriptor.setter())
                markBuffer.append(descriptor.setter());
        }
    }
    for (size_t i = 0; i < numProperties; i++) {
        object->methodTable()->defineOwnProperty(object, exec, propertyNames[i], descriptors[i], true);
        if (exec->hadException())
            return jsNull();
    }
    return object;
}