C++ DECLARE_THROW_SCOPE函数代码示例

static std::error_code getDomainList(ExecState& exec, const JSObject* arrayObject, Vector<String>& vector)
{
    VM& vm = exec.vm();
    auto scope = DECLARE_THROW_SCOPE(vm);

    ASSERT(vector.isEmpty());
    if (!arrayObject || !isJSArray(arrayObject))
        return ContentExtensionError::JSONInvalidDomainList;
    const JSArray* array = jsCast<const JSArray*>(arrayObject);
    
    unsigned length = array->length();
    for (unsigned i = 0; i < length; ++i) {
        const JSValue value = array->getIndex(&exec, i);
        if (scope.exception() || !value.isString())
            return ContentExtensionError::JSONInvalidDomainList;
        
        // Domains should be punycode encoded lower case.
        const String& domain = jsCast<JSString*>(value)->value(&exec);
        if (domain.isEmpty())
            return ContentExtensionError::JSONInvalidDomainList;
        if (!containsOnlyASCIIWithNoUppercase(domain))
            return ContentExtensionError::JSONDomainNotLowerCaseASCII;
        vector.append(domain);
    }
    return { };
}

bool JSLocation::getOwnPropertySlotDelegate(ExecState* exec, PropertyName propertyName, PropertySlot& slot)
{
    VM& vm = exec->vm();
    auto scope = DECLARE_THROW_SCOPE(vm);

    Frame* frame = wrapped().frame();
    if (!frame) {
        slot.setUndefined();
        return true;
    }

    // When accessing Location cross-domain, functions are always the native built-in ones.
    // See JSDOMWindow::getOwnPropertySlotDelegate for additional details.

    // Our custom code is only needed to implement the Window cross-domain scheme, so if access is
    // allowed, return false so the normal lookup will take place.
    String message;
    if (shouldAllowAccessToFrame(exec, frame, message))
        return false;

    // We only allow access to Location.replace() cross origin.
    // Make it read-only / non-configurable to prevent writes via defineProperty.
    if (propertyName == exec->propertyNames().replace) {
        slot.setCustom(this, ReadOnly | DontDelete | DontEnum, nonCachingStaticFunctionGetter<jsLocationInstanceFunctionReplace, 1>);
        return true;
    }

    throwSecurityError(*exec, scope, message);
    slot.setUndefined();
    return true;
}

JSValue IntlNumberFormat::formatNumber(ExecState& state, double number)
{
    VM& vm = state.vm();
    auto scope = DECLARE_THROW_SCOPE(vm);

    // 11.3.4 FormatNumber abstract operation (ECMA-402 2.0)
    if (!m_initializedNumberFormat)
        return throwTypeError(&state, scope, "Intl.NumberFormat.prototype.format called on value that's not an object initialized as a NumberFormat"_s);

    // Map negative zero to positive zero.
    if (!number)
        number = 0.0;

    UErrorCode status = U_ZERO_ERROR;
    Vector<UChar, 32> buffer(32);
    auto length = unum_formatDouble(m_numberFormat.get(), number, buffer.data(), buffer.size(), nullptr, &status);
    if (status == U_BUFFER_OVERFLOW_ERROR) {
        buffer.grow(length);
        status = U_ZERO_ERROR;
        unum_formatDouble(m_numberFormat.get(), number, buffer.data(), length, nullptr, &status);
    }
    if (U_FAILURE(status))
        return throwException(&state, scope, createError(&state, "Failed to format a number."_s));

    return jsString(&state, String(buffer.data(), length));
}

bool JSDOMWindow::preventExtensions(JSObject*, ExecState* exec)
{
    auto scope = DECLARE_THROW_SCOPE(exec->vm());

    throwTypeError(exec, scope, ASCIILiteral("Cannot prevent extensions on this object"));
    return false;
}

static EncodedJSValue JSC_HOST_CALL constructWeakSet(ExecState* exec)
{
    VM& vm = exec->vm();
    auto scope = DECLARE_THROW_SCOPE(vm);

    JSGlobalObject* globalObject = asInternalFunction(exec->jsCallee())->globalObject();
    Structure* weakSetStructure = InternalFunction::createSubclassStructure(exec, exec->newTarget(), globalObject->weakSetStructure());
    RETURN_IF_EXCEPTION(scope, encodedJSValue());
    JSWeakSet* weakSet = JSWeakSet::create(exec, weakSetStructure);
    JSValue iterable = exec->argument(0);
    if (iterable.isUndefinedOrNull())
        return JSValue::encode(weakSet);

    JSValue adderFunction = weakSet->JSObject::get(exec, vm.propertyNames->add);
    RETURN_IF_EXCEPTION(scope, encodedJSValue());

    CallData adderFunctionCallData;
    CallType adderFunctionCallType = getCallData(adderFunction, adderFunctionCallData);
    if (adderFunctionCallType == CallType::None)
        return JSValue::encode(throwTypeError(exec, scope));

    scope.release();
    forEachInIterable(exec, iterable, [&](VM&, ExecState* exec, JSValue nextValue) {
        MarkedArgumentBuffer arguments;
        arguments.append(nextValue);
        call(exec, adderFunction, adderFunctionCallType, adderFunctionCallData, weakSet, arguments);
    });

    return JSValue::encode(weakSet);
}

static void exportKey(ExecState& state, CryptoKeyFormat keyFormat, const CryptoKey& key, CryptoAlgorithm::VectorCallback callback, CryptoAlgorithm::VoidCallback failureCallback)
{
    VM& vm = state.vm();
    auto scope = DECLARE_THROW_SCOPE(vm);

    if (!key.extractable()) {
        throwTypeError(&state, scope, ASCIILiteral("Key is not extractable"));
        return;
    }

    switch (keyFormat) {
    case CryptoKeyFormat::Raw: {
        Vector<uint8_t> result;
        if (CryptoKeySerializationRaw::serialize(key, result))
            callback(result);
        else
            failureCallback();
        break;
    }
    case CryptoKeyFormat::JWK: {
        String result = JSCryptoKeySerializationJWK::serialize(&state, key);
        RETURN_IF_EXCEPTION(scope, void());
        CString utf8String = result.utf8(StrictConversion);
        Vector<uint8_t> resultBuffer;
        resultBuffer.append(utf8String.data(), utf8String.length());
        callback(resultBuffer);
        break;
    }
    default:
        throwTypeError(&state, scope, ASCIILiteral("Unsupported key format for export"));
        break;
    }
}

JSValue Database::toJS(ExecState* exec) const
{
    VM& vm = exec->vm();
    auto scope = DECLARE_THROW_SCOPE(vm);
    JSObject* result = constructEmptyObject(exec);
    
    JSArray* bytecodes = constructEmptyArray(exec, 0);
    RETURN_IF_EXCEPTION(scope, JSValue());
    for (unsigned i = 0; i < m_bytecodes.size(); ++i)
        bytecodes->putDirectIndex(exec, i, m_bytecodes[i].toJS(exec));
    result->putDirect(vm, exec->propertyNames().bytecodes, bytecodes);
    
    JSArray* compilations = constructEmptyArray(exec, 0);
    RETURN_IF_EXCEPTION(scope, JSValue());
    for (unsigned i = 0; i < m_compilations.size(); ++i)
        compilations->putDirectIndex(exec, i, m_compilations[i]->toJS(exec));
    result->putDirect(vm, exec->propertyNames().compilations, compilations);
    
    JSArray* events = constructEmptyArray(exec, 0);
    RETURN_IF_EXCEPTION(scope, JSValue());
    for (unsigned i = 0; i < m_events.size(); ++i)
        events->putDirectIndex(exec, i, m_events[i].toJS(exec));
    result->putDirect(vm, exec->propertyNames().events, events);
    
    return result;
}

EncodedJSValue JSC_HOST_CALL webAssemblyModuleCustomSections(ExecState* exec)
{
    VM& vm = exec->vm();
    auto* globalObject = exec->lexicalGlobalObject();
    auto throwScope = DECLARE_THROW_SCOPE(vm);

    JSWebAssemblyModule* module = jsDynamicCast<JSWebAssemblyModule*>(vm, exec->argument(0));
    if (!module)
        return JSValue::encode(throwException(exec, throwScope, createTypeError(exec, "WebAssembly.Module.customSections called with non WebAssembly.Module argument"_s)));

    const String sectionNameString = exec->argument(1).getString(exec);
    RETURN_IF_EXCEPTION(throwScope, { });

    JSArray* result = constructEmptyArray(exec, nullptr, globalObject);
    RETURN_IF_EXCEPTION(throwScope, { });

    const auto& customSections = module->moduleInformation().customSections;
    for (const Wasm::CustomSection& section : customSections) {
        if (String::fromUTF8(section.name) == sectionNameString) {
            auto buffer = ArrayBuffer::tryCreate(section.payload.data(), section.payload.size());
            if (!buffer)
                return JSValue::encode(throwException(exec, throwScope, createOutOfMemoryError(exec)));

            result->push(exec, JSArrayBuffer::create(vm, globalObject->arrayBufferStructure(ArrayBufferSharingMode::Default), WTFMove(buffer)));
            RETURN_IF_EXCEPTION(throwScope, { });
        }
    }

    return JSValue::encode(result);
}

EncodedJSValue JSC_HOST_CALL webAssemblyModuleImports(ExecState* exec)
{
    VM& vm = exec->vm();
    auto* globalObject = exec->lexicalGlobalObject();
    auto throwScope = DECLARE_THROW_SCOPE(vm);

    JSWebAssemblyModule* module = jsDynamicCast<JSWebAssemblyModule*>(vm, exec->argument(0));
    if (!module)
        return JSValue::encode(throwException(exec, throwScope, createTypeError(exec, "WebAssembly.Module.imports called with non WebAssembly.Module argument"_s)));

    JSArray* result = constructEmptyArray(exec, nullptr, globalObject);
    RETURN_IF_EXCEPTION(throwScope, { });

    const auto& imports = module->moduleInformation().imports;
    if (imports.size()) {
        Identifier module = Identifier::fromString(exec, "module");
        Identifier name = Identifier::fromString(exec, "name");
        Identifier kind = Identifier::fromString(exec, "kind");
        for (const Wasm::Import& imp : imports) {
            JSObject* obj = constructEmptyObject(exec);
            RETURN_IF_EXCEPTION(throwScope, { });
            obj->putDirect(vm, module, jsString(exec, String::fromUTF8(imp.module)));
            obj->putDirect(vm, name, jsString(exec, String::fromUTF8(imp.field)));
            obj->putDirect(vm, kind, jsString(exec, String(makeString(imp.kind))));
            result->push(exec, obj);
            RETURN_IF_EXCEPTION(throwScope, { });
        }
    }

    return JSValue::encode(result);
}

EncodedJSValue JSC_HOST_CALL constructJSWorker(ExecState& exec)
{
    VM& vm = exec.vm();
    auto scope = DECLARE_THROW_SCOPE(vm);

    DOMConstructorObject* jsConstructor = jsCast<DOMConstructorObject*>(exec.callee());

    if (!exec.argumentCount())
        return throwVMError(&exec, scope, createNotEnoughArgumentsError(&exec));

    String scriptURL = exec.uncheckedArgument(0).toWTFString(&exec);
    if (exec.hadException())
        return JSValue::encode(JSValue());

    // See section 4.8.2 step 14 of WebWorkers for why this is the lexicalGlobalObject.
    DOMWindow& window = asJSDOMWindow(exec.lexicalGlobalObject())->wrapped();

    ExceptionCode ec = 0;
    ASSERT(window.document());
    RefPtr<Worker> worker = Worker::create(*window.document(), scriptURL, ec);
    if (ec) {
        setDOMException(&exec, ec);
        return JSValue::encode(JSValue());
    }

    return JSValue::encode(toJSNewlyCreated(&exec, jsConstructor->globalObject(), WTFMove(worker)));
}

JSValue ScriptFunctionCall::call(bool& hadException)
{
    JSObject* thisObject = m_thisObject.jsObject();

    VM& vm = m_exec->vm();
    JSLockHolder lock(vm);
    auto scope = DECLARE_THROW_SCOPE(vm);

    JSValue function = thisObject->get(m_exec, Identifier::fromString(m_exec, m_name));
    if (UNLIKELY(scope.exception())) {
        hadException = true;
        return { };
    }

    CallData callData;
    CallType callType = getCallData(function, callData);
    if (callType == CallType::None)
        return { };

    JSValue result;
    NakedPtr<Exception> exception;
    if (m_callHandler)
        result = m_callHandler(m_exec, function, callType, callData, thisObject, m_arguments, exception);
    else
        result = JSC::call(m_exec, function, callType, callData, thisObject, m_arguments, exception);

    if (exception) {
        // Do not treat a terminated execution exception as having an exception. Just treat it as an empty result.
        hadException = !isTerminatedExecutionException(exception);
        return { };
    }

    return result;
}

static EncodedJSValue JSC_HOST_CALL constructArrayBuffer(ExecState* exec)
{
    VM& vm = exec->vm();
    auto scope = DECLARE_THROW_SCOPE(vm);

    JSArrayBufferConstructor* constructor =
        jsCast<JSArrayBufferConstructor*>(exec->jsCallee());
    
    unsigned length;
    if (exec->argumentCount()) {
        length = exec->uncheckedArgument(0).toIndex(exec, "length");
        RETURN_IF_EXCEPTION(scope, encodedJSValue());
    } else {
        // Although the documentation doesn't say so, it is in fact correct to say
        // "new ArrayBuffer()". The result is the same as allocating an array buffer
        // with a zero length.
        length = 0;
    }
    
    auto buffer = ArrayBuffer::tryCreate(length, 1);
    if (!buffer)
        return JSValue::encode(throwOutOfMemoryError(exec, scope));
    
    if (constructor->sharingMode() == ArrayBufferSharingMode::Shared)
        buffer->makeShared();
    
    ASSERT(constructor->sharingMode() == buffer->sharingMode());
    
    Structure* arrayBufferStructure = InternalFunction::createSubclassStructure(exec, exec->newTarget(), constructor->globalObject()->arrayBufferStructure(constructor->sharingMode()));
    RETURN_IF_EXCEPTION(scope, encodedJSValue());
    JSArrayBuffer* result = JSArrayBuffer::create(vm, arrayBufferStructure, WTFMove(buffer));
    
    return JSValue::encode(result);
}

static std::error_code getTypeFlags(ExecState& exec, const JSValue& typeValue, ResourceFlags& flags, uint16_t (*stringToType)(const String&))
{
    VM& vm = exec.vm();
    auto scope = DECLARE_THROW_SCOPE(vm);

    if (!typeValue.isObject())
        return { };

    const JSObject* object = typeValue.toObject(&exec);
    ASSERT(!scope.exception());
    if (!isJSArray(object))
        return ContentExtensionError::JSONInvalidTriggerFlagsArray;

    const JSArray* array = jsCast<const JSArray*>(object);
    
    unsigned length = array->length();
    for (unsigned i = 0; i < length; ++i) {
        const JSValue value = array->getIndex(&exec, i);
        if (scope.exception() || !value)
            return ContentExtensionError::JSONInvalidObjectInTriggerFlagsArray;
        
        String name = value.toWTFString(&exec);
        uint16_t type = stringToType(name);
        if (!type)
            return ContentExtensionError::JSONInvalidStringInTriggerFlagsArray;

        flags |= type;
    }

    return { };
}

// HTMLAllCollections are strange objects, they support both get and call.
static EncodedJSValue JSC_HOST_CALL callHTMLAllCollection(ExecState* exec)
{
    VM& vm = exec->vm();
    auto scope = DECLARE_THROW_SCOPE(vm);

    if (exec->argumentCount() < 1)
        return JSValue::encode(jsUndefined());

    // Do not use thisObj here. It can be the JSHTMLDocument, in the document.forms(i) case.
    JSHTMLAllCollection* jsCollection = jsCast<JSHTMLAllCollection*>(exec->callee());
    HTMLAllCollection& collection = jsCollection->wrapped();

    // Also, do we need the TypeError test here ?

    if (exec->argumentCount() == 1) {
        // Support for document.all(<index>) etc.
        String string = exec->argument(0).toString(exec)->value(exec);
        RETURN_IF_EXCEPTION(scope, encodedJSValue());
        if (Optional<uint32_t> index = parseIndex(*string.impl()))
            return JSValue::encode(toJS(exec, jsCollection->globalObject(), collection.item(index.value())));

        // Support for document.images('<name>') etc.
        return JSValue::encode(namedItems(*exec, jsCollection, Identifier::fromString(exec, string)));
    }

    // The second arg, if set, is the index of the item we want
    String string = exec->argument(0).toString(exec)->value(exec);
    RETURN_IF_EXCEPTION(scope, encodedJSValue());
    if (Optional<uint32_t> index = parseIndex(*exec->argument(1).toWTFString(exec).impl())) {
        if (auto* item = collection.namedItemWithIndex(string, index.value()))
            return JSValue::encode(toJS(exec, jsCollection->globalObject(), *item));
    }

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

JSValue JSWebKitSubtleCrypto::digest(ExecState& state)
{
    VM& vm = state.vm();
    auto scope = DECLARE_THROW_SCOPE(vm);

    if (state.argumentCount() < 2)
        return throwException(&state, scope, createNotEnoughArgumentsError(&state));

    auto algorithm = createAlgorithmFromJSValue(state, scope, state.uncheckedArgument(0));
    RETURN_IF_EXCEPTION(scope, { });

    auto parameters = JSCryptoAlgorithmDictionary::createParametersForDigest(state, scope, algorithm->identifier(), state.uncheckedArgument(0));
    RETURN_IF_EXCEPTION(scope, { });

    auto data = cryptoOperationDataFromJSValue(state, scope, state.uncheckedArgument(1));
    RETURN_IF_EXCEPTION(scope, { });

    RefPtr<DeferredPromise> wrapper = createDeferredPromise(state, domWindow());
    auto promise = wrapper->promise();
    auto successCallback = [wrapper](const Vector<uint8_t>& result) mutable {
        fulfillPromiseWithArrayBuffer(wrapper.releaseNonNull(), result.data(), result.size());
    };
    auto failureCallback = [wrapper]() mutable {
        wrapper->reject(); // FIXME: This should reject with an Exception.
    };

    auto result = algorithm->digest(*parameters, data, WTFMove(successCallback), WTFMove(failureCallback));
    if (result.hasException()) {
        propagateException(state, scope, result.releaseException());
        return { };
    }

    return promise;
}