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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim:set ts=2 sw=2 sts=2 et cindent: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
#include "mozilla/dom/TransformStream.h"
#include "StreamUtils.h"
#include "TransformerCallbackHelpers.h"
#include "UnderlyingSourceCallbackHelpers.h"
#include "js/TypeDecls.h"
#include "mozilla/Attributes.h"
#include "mozilla/dom/Promise.h"
#include "mozilla/dom/Promise-inl.h"
#include "mozilla/dom/WritableStream.h"
#include "mozilla/dom/ReadableStream.h"
#include "mozilla/dom/RootedDictionary.h"
#include "mozilla/dom/TransformStreamBinding.h"
#include "mozilla/dom/TransformerBinding.h"
#include "nsWrapperCache.h"
namespace mozilla::dom {
using namespace streams_abstract;
NS_IMPL_CYCLE_COLLECTION_WRAPPERCACHE(TransformStream, mGlobal,
mBackpressureChangePromise, mController,
mReadable, mWritable)
NS_IMPL_CYCLE_COLLECTING_ADDREF(TransformStream)
NS_IMPL_CYCLE_COLLECTING_RELEASE(TransformStream)
NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(TransformStream)
NS_WRAPPERCACHE_INTERFACE_MAP_ENTRY
NS_INTERFACE_MAP_ENTRY(nsISupports)
NS_INTERFACE_MAP_END
// (except this instead creates a new TransformStream rather than accepting an
// existing instance)
already_AddRefed<TransformStream> TransformStream::CreateGeneric(
const GlobalObject& aGlobal, TransformerAlgorithmsWrapper& aAlgorithms,
ErrorResult& aRv) {
// Step 1. Let writableHighWaterMark be 1.
double writableHighWaterMark = 1;
// Step 2. Let writableSizeAlgorithm be an algorithm that returns 1.
// Note: Callers should recognize nullptr as a callback that returns 1. See
// also WritableStream::Constructor for this design decision.
RefPtr<QueuingStrategySize> writableSizeAlgorithm;
// Step 3. Let readableHighWaterMark be 0.
double readableHighWaterMark = 0;
// Step 4. Let readableSizeAlgorithm be an algorithm that returns 1.
// Note: Callers should recognize nullptr as a callback that returns 1. See
// also ReadableStream::Constructor for this design decision.
RefPtr<QueuingStrategySize> readableSizeAlgorithm;
// Step 5. Let transformAlgorithmWrapper be an algorithm that runs these steps
// given a value chunk:
// Step 6. Let flushAlgorithmWrapper be an algorithm that runs these steps:
// (Done by TransformerAlgorithmsWrapper)
// Step 7. Let startPromise be a promise resolved with undefined.
nsCOMPtr<nsIGlobalObject> global = do_QueryInterface(aGlobal.GetAsSupports());
RefPtr<Promise> startPromise =
Promise::CreateResolvedWithUndefined(global, aRv);
if (!startPromise) {
return nullptr;
}
// Step 8. Perform ! InitializeTransformStream(stream, startPromise,
// writableHighWaterMark, writableSizeAlgorithm, readableHighWaterMark,
// readableSizeAlgorithm).
RefPtr<TransformStream> stream =
new TransformStream(global, nullptr, nullptr);
stream->Initialize(aGlobal.Context(), startPromise, writableHighWaterMark,
writableSizeAlgorithm, readableHighWaterMark,
readableSizeAlgorithm, aRv);
if (aRv.Failed()) {
return nullptr;
}
// Step 9. Let controller be a new TransformStreamDefaultController.
auto controller = MakeRefPtr<TransformStreamDefaultController>(global);
// Step 10. Perform ! SetUpTransformStreamDefaultController(stream,
// controller, transformAlgorithmWrapper, flushAlgorithmWrapper).
SetUpTransformStreamDefaultController(aGlobal.Context(), *stream, *controller,
aAlgorithms);
return stream.forget();
}
TransformStream::TransformStream(nsIGlobalObject* aGlobal) : mGlobal(aGlobal) {
mozilla::HoldJSObjects(this);
}
TransformStream::TransformStream(nsIGlobalObject* aGlobal,
ReadableStream* aReadable,
WritableStream* aWritable)
: mGlobal(aGlobal), mReadable(aReadable), mWritable(aWritable) {
mozilla::HoldJSObjects(this);
}
TransformStream::~TransformStream() { mozilla::DropJSObjects(this); }
JSObject* TransformStream::WrapObject(JSContext* aCx,
JS::Handle<JSObject*> aGivenProto) {
return TransformStream_Binding::Wrap(aCx, this, aGivenProto);
}
namespace streams_abstract {
void TransformStreamErrorWritableAndUnblockWrite(JSContext* aCx,
TransformStream* aStream,
JS::Handle<JS::Value> aError,
ErrorResult& aRv) {
// Step 1: Perform !
// TransformStreamDefaultControllerClearAlgorithms(stream.[[controller]]).
aStream->Controller()->SetAlgorithms(nullptr);
// Step 2: Perform !
// WritableStreamDefaultControllerErrorIfNeeded(stream.[[writable]].[[controller]],
// e).
WritableStreamDefaultControllerErrorIfNeeded(
aCx, MOZ_KnownLive(aStream->Writable()->Controller()), aError, aRv);
if (aRv.Failed()) {
return;
}
// Step 3: If stream.[[backpressure]] is true, perform !
// TransformStreamSetBackpressure(stream, false).
if (aStream->Backpressure()) {
aStream->SetBackpressure(false);
}
}
void TransformStreamError(JSContext* aCx, TransformStream* aStream,
JS::Handle<JS::Value> aError, ErrorResult& aRv) {
// Step 1: Perform !
// ReadableStreamDefaultControllerError(stream.[[readable]].[[controller]],
// e).
ReadableStreamDefaultControllerError(
aCx, aStream->Readable()->Controller()->AsDefault(), aError, aRv);
if (aRv.Failed()) {
return;
}
// Step 2: Perform ! TransformStreamErrorWritableAndUnblockWrite(stream, e).
TransformStreamErrorWritableAndUnblockWrite(aCx, aStream, aError, aRv);
}
} // namespace streams_abstract
MOZ_CAN_RUN_SCRIPT static already_AddRefed<Promise>
TransformStreamDefaultControllerPerformTransform(
JSContext* aCx, TransformStreamDefaultController* aController,
JS::Handle<JS::Value> aChunk, ErrorResult& aRv) {
// Step 1: Let transformPromise be the result of performing
// controller.[[transformAlgorithm]], passing chunk.
RefPtr<TransformerAlgorithmsBase> algorithms = aController->Algorithms();
RefPtr<Promise> transformPromise =
algorithms->TransformCallback(aCx, aChunk, *aController, aRv);
if (aRv.Failed()) {
return nullptr;
}
// Step 2: Return the result of reacting to transformPromise with the
// following rejection steps given the argument r:
auto result = transformPromise->CatchWithCycleCollectedArgs(
[](JSContext* aCx, JS::Handle<JS::Value> aError, ErrorResult& aRv,
const RefPtr<TransformStreamDefaultController>& aController)
MOZ_CAN_RUN_SCRIPT_BOUNDARY_LAMBDA -> already_AddRefed<Promise> {
// Step 2.1: Perform ! TransformStreamError(controller.[[stream]],
// r).
TransformStreamError(aCx, MOZ_KnownLive(aController->Stream()),
aError, aRv);
if (aRv.Failed()) {
return nullptr;
}
// Step 2.2: Throw r.
JS::Rooted<JS::Value> r(aCx, aError);
aRv.MightThrowJSException();
aRv.ThrowJSException(aCx, r);
return nullptr;
},
RefPtr(aController));
if (result.isErr()) {
aRv.Throw(result.unwrapErr());
return nullptr;
}
return result.unwrap().forget();
}
class TransformStreamUnderlyingSinkAlgorithms final
: public UnderlyingSinkAlgorithmsBase {
public:
NS_DECL_ISUPPORTS_INHERITED
NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED(
TransformStreamUnderlyingSinkAlgorithms, UnderlyingSinkAlgorithmsBase)
TransformStreamUnderlyingSinkAlgorithms(Promise* aStartPromise,
TransformStream* aStream)
: mStartPromise(aStartPromise), mStream(aStream) {}
void StartCallback(JSContext* aCx,
WritableStreamDefaultController& aController,
JS::MutableHandle<JS::Value> aRetVal,
ErrorResult& aRv) override {
// Step 1. Let startAlgorithm be an algorithm that returns startPromise.
// (Same as TransformStreamUnderlyingSourceAlgorithms::StartCallback)
aRetVal.setObject(*mStartPromise->PromiseObj());
}
MOZ_CAN_RUN_SCRIPT already_AddRefed<Promise> WriteCallback(
JSContext* aCx, JS::Handle<JS::Value> aChunk,
WritableStreamDefaultController& aController, ErrorResult& aRv) override {
// Step 2. Let writeAlgorithm be the following steps, taking a chunk
// argument:
// Step 2.1. Return ! TransformStreamDefaultSinkWriteAlgorithm(stream,
// chunk).
// Inlining TransformStreamDefaultSinkWriteAlgorithm here:
// Step 1: Assert: stream.[[writable]].[[state]] is "writable".
MOZ_ASSERT(mStream->Writable()->State() ==
WritableStream::WriterState::Writable);
// Step 2: Let controller be stream.[[controller]].
RefPtr<TransformStreamDefaultController> controller = mStream->Controller();
// Step 3: If stream.[[backpressure]] is true,
if (mStream->Backpressure()) {
// Step 3.1: Let backpressureChangePromise be
// stream.[[backpressureChangePromise]].
RefPtr<Promise> backpressureChangePromise =
mStream->BackpressureChangePromise();
// Step 3.2: Assert: backpressureChangePromise is not undefined.
MOZ_ASSERT(backpressureChangePromise);
// Step 3.3: Return the result of reacting to backpressureChangePromise
// with the following fulfillment steps:
auto result = backpressureChangePromise->ThenWithCycleCollectedArgsJS(
[](JSContext* aCx, JS::Handle<JS::Value>, ErrorResult& aRv,
const RefPtr<TransformStream>& aStream,
const RefPtr<TransformStreamDefaultController>& aController,
JS::Handle<JS::Value> aChunk)
MOZ_CAN_RUN_SCRIPT_BOUNDARY_LAMBDA -> already_AddRefed<Promise> {
// Step 1: Let writable be stream.[[writable]].
RefPtr<WritableStream> writable = aStream->Writable();
// Step 2: Let state be writable.[[state]].
WritableStream::WriterState state = writable->State();
// Step 3: If state is "erroring", throw
// writable.[[storedError]].
if (state == WritableStream::WriterState::Erroring) {
JS::Rooted<JS::Value> storedError(aCx,
writable->StoredError());
aRv.MightThrowJSException();
aRv.ThrowJSException(aCx, storedError);
return nullptr;
}
// Step 4: Assert: state is "writable".
MOZ_ASSERT(state == WritableStream::WriterState::Writable);
// Step 5: Return !
// TransformStreamDefaultControllerPerformTransform(controller,
// chunk).
return TransformStreamDefaultControllerPerformTransform(
aCx, aController, aChunk, aRv);
},
std::make_tuple(mStream, controller), std::make_tuple(aChunk));
if (result.isErr()) {
aRv.Throw(result.unwrapErr());
return nullptr;
}
return result.unwrap().forget();
}
// Step 4: Return !
// TransformStreamDefaultControllerPerformTransform(controller, chunk).
return TransformStreamDefaultControllerPerformTransform(aCx, controller,
aChunk, aRv);
}
MOZ_CAN_RUN_SCRIPT already_AddRefed<Promise> AbortCallback(
JSContext* aCx, const Optional<JS::Handle<JS::Value>>& aReason,
ErrorResult& aRv) override {
// Step 3. Let abortAlgorithm be the following steps, taking a reason
// argument:
// Step 3.1. Return ! TransformStreamDefaultSinkAbortAlgorithm(stream,
// reason).
// Inlining TransformStreamDefaultSinkAbortAlgorithm here:
// Step 1:Perform ! TransformStreamError(stream, reason).
TransformStreamError(
aCx, mStream,
aReason.WasPassed() ? aReason.Value() : JS::UndefinedHandleValue, aRv);
if (aRv.Failed()) {
return nullptr;
}
// Step 2: Return a promise resolved with undefined.
return Promise::CreateResolvedWithUndefined(mStream->GetParentObject(),
aRv);
}
MOZ_CAN_RUN_SCRIPT already_AddRefed<Promise> CloseCallback(
JSContext* aCx, ErrorResult& aRv) override {
// Step 4. Let closeAlgorithm be the following steps:
// Step 4.1. Return ! TransformStreamDefaultSinkCloseAlgorithm(stream).
// Inlining TransformStreamDefaultSinkCloseAlgorithm here:
// Step 1: Let readable be stream.[[readable]].
RefPtr<ReadableStream> readable = mStream->Readable();
// Step 2: Let controller be stream.[[controller]].
RefPtr<TransformStreamDefaultController> controller = mStream->Controller();
// Step 3: Let flushPromise be the result of performing
// controller.[[flushAlgorithm]].
RefPtr<TransformerAlgorithmsBase> algorithms = controller->Algorithms();
RefPtr<Promise> flushPromise =
algorithms->FlushCallback(aCx, *controller, aRv);
if (aRv.Failed()) {
return nullptr;
}
// Step 4: Perform !
// TransformStreamDefaultControllerClearAlgorithms(controller).
controller->SetAlgorithms(nullptr);
// Step 5: Return the result of reacting to flushPromise:
Result<RefPtr<Promise>, nsresult> result =
flushPromise->ThenCatchWithCycleCollectedArgs(
[](JSContext* aCx, JS::Handle<JS::Value> aValue, ErrorResult& aRv,
const RefPtr<ReadableStream>& aReadable,
const RefPtr<TransformStream>& aStream)
MOZ_CAN_RUN_SCRIPT_BOUNDARY_LAMBDA
-> already_AddRefed<Promise> {
// Step 5.1: If flushPromise was fulfilled, then:
// Step 5.1.1: If readable.[[state]] is "errored", throw
// readable.[[storedError]].
if (aReadable->State() ==
ReadableStream::ReaderState::Errored) {
JS::Rooted<JS::Value> storedError(aCx,
aReadable->StoredError());
aRv.MightThrowJSException();
aRv.ThrowJSException(aCx, storedError);
return nullptr;
}
// Step 5.1.2: Perform !
// ReadableStreamDefaultControllerClose(readable.[[controller]]).
ReadableStreamDefaultControllerClose(
aCx, MOZ_KnownLive(aReadable->Controller()->AsDefault()),
aRv);
return nullptr;
},
[](JSContext* aCx, JS::Handle<JS::Value> aValue, ErrorResult& aRv,
const RefPtr<ReadableStream>& aReadable,
const RefPtr<TransformStream>& aStream)
MOZ_CAN_RUN_SCRIPT_BOUNDARY_LAMBDA
-> already_AddRefed<Promise> {
// Step 5.2: If flushPromise was rejected with reason r, then:
// Step 5.2.1: Perform ! TransformStreamError(stream, r).
TransformStreamError(aCx, aStream, aValue, aRv);
if (aRv.Failed()) {
return nullptr;
}
// Step 5.2.2: Throw readable.[[storedError]].
JS::Rooted<JS::Value> storedError(aCx,
aReadable->StoredError());
aRv.MightThrowJSException();
aRv.ThrowJSException(aCx, storedError);
return nullptr;
},
readable, mStream);
if (result.isErr()) {
aRv.Throw(result.unwrapErr());
return nullptr;
}
return result.unwrap().forget();
}
protected:
~TransformStreamUnderlyingSinkAlgorithms() override = default;
private:
RefPtr<Promise> mStartPromise;
// MOZ_KNOWN_LIVE because it won't be reassigned
MOZ_KNOWN_LIVE RefPtr<TransformStream> mStream;
};
NS_IMPL_CYCLE_COLLECTION_INHERITED(TransformStreamUnderlyingSinkAlgorithms,
UnderlyingSinkAlgorithmsBase, mStartPromise,
mStream)
NS_IMPL_ADDREF_INHERITED(TransformStreamUnderlyingSinkAlgorithms,
UnderlyingSinkAlgorithmsBase)
NS_IMPL_RELEASE_INHERITED(TransformStreamUnderlyingSinkAlgorithms,
UnderlyingSinkAlgorithmsBase)
NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(TransformStreamUnderlyingSinkAlgorithms)
NS_INTERFACE_MAP_END_INHERITING(UnderlyingSinkAlgorithmsBase)
class TransformStreamUnderlyingSourceAlgorithms final
: public UnderlyingSourceAlgorithmsBase {
public:
NS_DECL_ISUPPORTS_INHERITED
NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED(
TransformStreamUnderlyingSourceAlgorithms, UnderlyingSourceAlgorithmsBase)
TransformStreamUnderlyingSourceAlgorithms(Promise* aStartPromise,
TransformStream* aStream)
: mStartPromise(aStartPromise), mStream(aStream) {}
void StartCallback(JSContext* aCx, ReadableStreamController& aController,
JS::MutableHandle<JS::Value> aRetVal,
ErrorResult& aRv) override {
// Step 1. Let startAlgorithm be an algorithm that returns startPromise.
// (Same as TransformStreamUnderlyingSinkAlgorithms::StartCallback)
aRetVal.setObject(*mStartPromise->PromiseObj());
}
already_AddRefed<Promise> PullCallback(JSContext* aCx,
ReadableStreamController& aController,
ErrorResult& aRv) override {
// Step 6. Let pullAlgorithm be the following steps:
// Step 6.1. Return ! TransformStreamDefaultSourcePullAlgorithm(stream).
// Inlining TransformStreamDefaultSourcePullAlgorithm here:
// Step 1: Assert: stream.[[backpressure]] is true.
MOZ_ASSERT(mStream->Backpressure());
// Step 2: Assert: stream.[[backpressureChangePromise]] is not undefined.
MOZ_ASSERT(mStream->BackpressureChangePromise());
// Step 3: Perform ! TransformStreamSetBackpressure(stream, false).
mStream->SetBackpressure(false);
// Step 4: Return stream.[[backpressureChangePromise]].
return do_AddRef(mStream->BackpressureChangePromise());
}
MOZ_CAN_RUN_SCRIPT already_AddRefed<Promise> CancelCallback(
JSContext* aCx, const Optional<JS::Handle<JS::Value>>& aReason,
ErrorResult& aRv) override {
// Step 7. Let cancelAlgorithm be the following steps, taking a reason
// argument:
// Step 7.1. Perform ! TransformStreamErrorWritableAndUnblockWrite(stream,
// reason).
TransformStreamErrorWritableAndUnblockWrite(
aCx, mStream,
aReason.WasPassed() ? aReason.Value() : JS::UndefinedHandleValue, aRv);
if (aRv.Failed()) {
return nullptr;
}
// Step 7.2. Return a promise resolved with undefined.
return Promise::CreateResolvedWithUndefined(mStream->GetParentObject(),
aRv);
}
protected:
~TransformStreamUnderlyingSourceAlgorithms() override = default;
private:
RefPtr<Promise> mStartPromise;
// MOZ_KNOWNLIVE because it will never be reassigned
MOZ_KNOWN_LIVE RefPtr<TransformStream> mStream;
};
NS_IMPL_CYCLE_COLLECTION_INHERITED(TransformStreamUnderlyingSourceAlgorithms,
UnderlyingSourceAlgorithmsBase,
mStartPromise, mStream)
NS_IMPL_ADDREF_INHERITED(TransformStreamUnderlyingSourceAlgorithms,
UnderlyingSourceAlgorithmsBase)
NS_IMPL_RELEASE_INHERITED(TransformStreamUnderlyingSourceAlgorithms,
UnderlyingSourceAlgorithmsBase)
NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(
TransformStreamUnderlyingSourceAlgorithms)
NS_INTERFACE_MAP_END_INHERITING(UnderlyingSourceAlgorithmsBase)
void TransformStream::SetBackpressure(bool aBackpressure) {
// Step 1. Assert: stream.[[backpressure]] is not backpressure.
MOZ_ASSERT(Backpressure() != aBackpressure);
// Step 2. If stream.[[backpressureChangePromise]] is not undefined, resolve
// stream.[[backpressureChangePromise]] with undefined.
if (Promise* promise = BackpressureChangePromise()) {
promise->MaybeResolveWithUndefined();
}
// Step 3. Set stream.[[backpressureChangePromise]] to a new promise.
RefPtr<Promise> promise = Promise::CreateInfallible(GetParentObject());
mBackpressureChangePromise = promise;
// Step 4. Set stream.[[backpressure]] to backpressure.
mBackpressure = aBackpressure;
}
void TransformStream::Initialize(JSContext* aCx, Promise* aStartPromise,
double aWritableHighWaterMark,
QueuingStrategySize* aWritableSizeAlgorithm,
double aReadableHighWaterMark,
QueuingStrategySize* aReadableSizeAlgorithm,
ErrorResult& aRv) {
// Step 1 - 4
auto sinkAlgorithms =
MakeRefPtr<TransformStreamUnderlyingSinkAlgorithms>(aStartPromise, this);
// Step 5. Set stream.[[writable]] to ! CreateWritableStream(startAlgorithm,
// writeAlgorithm, closeAlgorithm, abortAlgorithm, writableHighWaterMark,
// writableSizeAlgorithm).
mWritable = WritableStream::CreateAbstract(
aCx, MOZ_KnownLive(mGlobal), sinkAlgorithms, aWritableHighWaterMark,
aWritableSizeAlgorithm, aRv);
if (aRv.Failed()) {
return;
}
// Step 6 - 7
auto sourceAlgorithms = MakeRefPtr<TransformStreamUnderlyingSourceAlgorithms>(
aStartPromise, this);
// Step 8. Set stream.[[readable]] to ! CreateReadableStream(startAlgorithm,
// pullAlgorithm, cancelAlgorithm, readableHighWaterMark,
// readableSizeAlgorithm).
mReadable = ReadableStream::CreateAbstract(
aCx, MOZ_KnownLive(mGlobal), sourceAlgorithms,
Some(aReadableHighWaterMark), aReadableSizeAlgorithm, aRv);
if (aRv.Failed()) {
return;
}
// Step 9. Set stream.[[backpressure]] and
// stream.[[backpressureChangePromise]] to undefined.
// Note(krosylight): The spec allows setting [[backpressure]] as undefined,
// but I don't see why it should be. Since the spec also allows strict boolean
// type, and this is only to not trigger assertion inside the setter, we just
// set it as false.
mBackpressure = false;
mBackpressureChangePromise = nullptr;
// Step 10. Perform ! TransformStreamSetBackpressure(stream, true).
SetBackpressure(true);
if (aRv.Failed()) {
return;
}
// Step 11. Set stream.[[controller]] to undefined.
mController = nullptr;
}
already_AddRefed<TransformStream> TransformStream::Constructor(
const GlobalObject& aGlobal,
const Optional<JS::Handle<JSObject*>>& aTransformer,
const QueuingStrategy& aWritableStrategy,
const QueuingStrategy& aReadableStrategy, ErrorResult& aRv) {
// Step 1. If transformer is missing, set it to null.
JS::Rooted<JSObject*> transformerObj(
aGlobal.Context(),
aTransformer.WasPassed() ? aTransformer.Value() : nullptr);
// Step 2. Let transformerDict be transformer, converted to an IDL value of
// type Transformer.
RootedDictionary<Transformer> transformerDict(aGlobal.Context());
if (transformerObj) {
JS::Rooted<JS::Value> objValue(aGlobal.Context(),
JS::ObjectValue(*transformerObj));
dom::BindingCallContext callCx(aGlobal.Context(),
"TransformStream.constructor");
aRv.MightThrowJSException();
if (!transformerDict.Init(callCx, objValue)) {
aRv.StealExceptionFromJSContext(aGlobal.Context());
return nullptr;
}
}
// Step 3. If transformerDict["readableType"] exists, throw a RangeError
// exception.
if (!transformerDict.mReadableType.isUndefined()) {
aRv.ThrowRangeError(
"`readableType` is unsupported and preserved for future use");
return nullptr;
}
// Step 4. If transformerDict["writableType"] exists, throw a RangeError
// exception.
if (!transformerDict.mWritableType.isUndefined()) {
aRv.ThrowRangeError(
"`writableType` is unsupported and preserved for future use");
return nullptr;
}
// Step 5. Let readableHighWaterMark be ?
// ExtractHighWaterMark(readableStrategy, 0).
double readableHighWaterMark =
ExtractHighWaterMark(aReadableStrategy, 0, aRv);
if (aRv.Failed()) {
return nullptr;
}
// Step 6. Let readableSizeAlgorithm be !
// ExtractSizeAlgorithm(readableStrategy).
// Note: Callers should recognize nullptr as a callback that returns 1. See
// also ReadableStream::Constructor for this design decision.
RefPtr<QueuingStrategySize> readableSizeAlgorithm =
aReadableStrategy.mSize.WasPassed() ? &aReadableStrategy.mSize.Value()
: nullptr;
// Step 7. Let writableHighWaterMark be ?
// ExtractHighWaterMark(writableStrategy, 1).
double writableHighWaterMark =
ExtractHighWaterMark(aWritableStrategy, 1, aRv);
if (aRv.Failed()) {
return nullptr;
}
// Step 8. Let writableSizeAlgorithm be !
// ExtractSizeAlgorithm(writableStrategy).
// Note: Callers should recognize nullptr as a callback that returns 1. See
// also WritableStream::Constructor for this design decision.
RefPtr<QueuingStrategySize> writableSizeAlgorithm =
aWritableStrategy.mSize.WasPassed() ? &aWritableStrategy.mSize.Value()
: nullptr;
// Step 9. Let startPromise be a new promise.
nsCOMPtr<nsIGlobalObject> global = do_QueryInterface(aGlobal.GetAsSupports());
RefPtr<Promise> startPromise = Promise::CreateInfallible(global);
// Step 10. Perform ! InitializeTransformStream(this, startPromise,
// writableHighWaterMark, writableSizeAlgorithm, readableHighWaterMark,
// readableSizeAlgorithm).
RefPtr<TransformStream> transformStream = new TransformStream(global);
transformStream->Initialize(
aGlobal.Context(), startPromise, writableHighWaterMark,
writableSizeAlgorithm, readableHighWaterMark, readableSizeAlgorithm, aRv);
if (aRv.Failed()) {
return nullptr;
}
// Step 11. Perform ?
// SetUpTransformStreamDefaultControllerFromTransformer(this, transformer,
// transformerDict).
SetUpTransformStreamDefaultControllerFromTransformer(
aGlobal.Context(), *transformStream, transformerObj, transformerDict);
// Step 12. If transformerDict["start"] exists, then resolve startPromise with
// the result of invoking transformerDict["start"] with argument list «
// this.[[controller]] » and callback this value transformer.
if (transformerDict.mStart.WasPassed()) {
RefPtr<TransformerStartCallback> callback = transformerDict.mStart.Value();
RefPtr<TransformStreamDefaultController> controller =
transformStream->Controller();
JS::Rooted<JS::Value> retVal(aGlobal.Context());
callback->Call(transformerObj, *controller, &retVal, aRv,
"Transformer.start", CallbackFunction::eRethrowExceptions);
if (aRv.Failed()) {
return nullptr;
}
startPromise->MaybeResolve(retVal);
} else {
// Step 13. Otherwise, resolve startPromise with undefined.
startPromise->MaybeResolveWithUndefined();
}
return transformStream.forget();
}
} // namespace mozilla::dom