gecko-dev/dom/streams/ReadableStream.h

/* -*- 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
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef mozilla_dom_ReadableStream_h
#define mozilla_dom_ReadableStream_h

#include "js/TypeDecls.h"
#include "js/Value.h"
#include "mozilla/Attributes.h"
#include "mozilla/ErrorResult.h"
#include "mozilla/dom/BindingDeclarations.h"
#include "mozilla/dom/QueuingStrategyBinding.h"
#include "mozilla/dom/ReadableStreamController.h"
#include "mozilla/dom/ReadableStreamDefaultController.h"
#include "mozilla/dom/UnderlyingSourceCallbackHelpers.h"
#include "nsCycleCollectionParticipant.h"
#include "nsWrapperCache.h"

namespace mozilla::dom {

class Promise;
class ReadableStreamGenericReader;
class ReadableStreamDefaultReader;
class ReadableStreamGenericReader;
struct ReadableStreamGetReaderOptions;
struct ReadIntoRequest;
class WritableStream;
struct ReadableWritablePair;
struct StreamPipeOptions;

using ReadableStreamReader =
    ReadableStreamDefaultReaderOrReadableStreamBYOBReader;
using OwningReadableStreamReader =
    OwningReadableStreamDefaultReaderOrReadableStreamBYOBReader;
class NativeUnderlyingSource;
class BodyStreamHolder;
class UniqueMessagePortId;
class MessagePort;

class ReadableStream final : public nsISupports, public nsWrapperCache {
 public:
  NS_DECL_CYCLE_COLLECTING_ISUPPORTS
  NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS(ReadableStream)

 protected:
  ~ReadableStream();

  nsCOMPtr<nsIGlobalObject> mGlobal;

 public:
  explicit ReadableStream(const GlobalObject& aGlobal);
  explicit ReadableStream(nsIGlobalObject* aGlobal);

  enum class ReaderState { Readable, Closed, Errored };

  // Slot Getter/Setters:
 public:
  MOZ_KNOWN_LIVE ReadableStreamController* Controller() { return mController; }
  ReadableStreamDefaultController* DefaultController() {
    MOZ_ASSERT(mController && mController->IsDefault());
    return mController->AsDefault();
  }
  void SetController(ReadableStreamController& aController) {
    MOZ_ASSERT(!mController);
    mController = &aController;
  }

  bool Disturbed() const { return mDisturbed; }
  void SetDisturbed(bool aDisturbed) { mDisturbed = aDisturbed; }

  ReadableStreamGenericReader* GetReader() { return mReader; }
  void SetReader(ReadableStreamGenericReader* aReader);

  ReadableStreamDefaultReader* GetDefaultReader();

  ReaderState State() const { return mState; }
  void SetState(const ReaderState& aState) { mState = aState; }

  JS::Value StoredError() const { return mStoredError; }
  void SetStoredError(JS::Handle<JS::Value> aStoredError) {
    mStoredError = aStoredError;
  }

  UnderlyingSourceAlgorithmsBase* GetAlgorithms() const { return mAlgorithms; }
  void SetErrorAlgorithm(UnderlyingSourceAlgorithmsBase* aAlgorithms) {
    mAlgorithms = aAlgorithms;
  }

  void SetNativeUnderlyingSource(BodyStreamHolder* aUnderlyingSource);
  BodyStreamHolder* GetNativeUnderlyingSource() {
    return mNativeUnderlyingSource;
  }
  bool HasNativeUnderlyingSource() { return mNativeUnderlyingSource; }

  void ReleaseObjects();

  // [Transferable]
  // https://html.spec.whatwg.org/multipage/structured-data.html#transfer-steps
  MOZ_CAN_RUN_SCRIPT bool Transfer(JSContext* aCx,
                                   UniqueMessagePortId& aPortId);
  // https://html.spec.whatwg.org/multipage/structured-data.html#transfer-receiving-steps
  static MOZ_CAN_RUN_SCRIPT bool ReceiveTransfer(
      JSContext* aCx, nsIGlobalObject* aGlobal, MessagePort& aPort,
      JS::MutableHandle<JSObject*> aReturnObject);

 public:
  nsIGlobalObject* GetParentObject() const { return mGlobal; }

  JSObject* WrapObject(JSContext* aCx,
                       JS::Handle<JSObject*> aGivenProto) override;

  MOZ_CAN_RUN_SCRIPT static already_AddRefed<ReadableStream> Create(
      JSContext* aCx, nsIGlobalObject* aGlobal,
      BodyStreamHolder* aUnderlyingSource, ErrorResult& aRv);

  // IDL Methods
  // TODO: Use MOZ_CAN_RUN_SCRIPT when IDL constructors can use it (bug 1749042)
  MOZ_CAN_RUN_SCRIPT_BOUNDARY static already_AddRefed<ReadableStream>
  Constructor(const GlobalObject& aGlobal,
              const Optional<JS::Handle<JSObject*>>& aUnderlyingSource,
              const QueuingStrategy& aStrategy, ErrorResult& aRv);

  bool Locked() const;

  MOZ_CAN_RUN_SCRIPT already_AddRefed<Promise> Cancel(
      JSContext* cx, JS::Handle<JS::Value> aReason, ErrorResult& aRv);

  void GetReader(const ReadableStreamGetReaderOptions& aOptions,
                 OwningReadableStreamReader& resultReader, ErrorResult& aRv);

  MOZ_CAN_RUN_SCRIPT already_AddRefed<ReadableStream> PipeThrough(
      const ReadableWritablePair& aTransform, const StreamPipeOptions& aOptions,
      ErrorResult& aRv);

  MOZ_CAN_RUN_SCRIPT already_AddRefed<Promise> PipeTo(
      WritableStream& aDestinaton, const StreamPipeOptions& aOptions,
      ErrorResult& aRv);

  MOZ_CAN_RUN_SCRIPT void Tee(JSContext* aCx,
                              nsTArray<RefPtr<ReadableStream>>& aResult,
                              ErrorResult& aRv);

  // Internal Slots:
 private:
  RefPtr<ReadableStreamController> mController;
  bool mDisturbed = false;
  RefPtr<ReadableStreamGenericReader> mReader;
  ReaderState mState = ReaderState::Readable;
  JS::Heap<JS::Value> mStoredError;

  // Optional Callback for erroring a stream.
  RefPtr<UnderlyingSourceAlgorithmsBase> mAlgorithms;

  // Optional strong reference to an Underlying Source; This
  // exists because NativeUnderlyingSource callbacks don't hold
  // a strong reference to the underlying source: So we need
  // something else to hold onto that. As well, some of the integration
  // desires the ability to extract the underlying source from the
  // ReadableStream.
  //
  // While theoretically this ought to be some base class type to support
  // multiple native underlying source types, I'm not sure what base class
  // makes any sense for BodyStream, and given there's only body streams
  // as the underlying source right now, I'm going to punt that problem to
  // the future where we need to provide other native underlying sources
  // (i.e. perhaps WebTransport.)
  RefPtr<BodyStreamHolder> mNativeUnderlyingSource;
};

bool IsReadableStreamLocked(ReadableStream* aStream);

double ReadableStreamGetNumReadRequests(ReadableStream* aStream);

void ReadableStreamError(JSContext* aCx, ReadableStream* aStream,
                         JS::Handle<JS::Value> aValue, ErrorResult& aRv);

MOZ_CAN_RUN_SCRIPT void ReadableStreamClose(JSContext* aCx,
                                            ReadableStream* aStream,
                                            ErrorResult& aRv);

MOZ_CAN_RUN_SCRIPT void ReadableStreamFulfillReadRequest(
    JSContext* aCx, ReadableStream* aStream, JS::Handle<JS::Value> aChunk,
    bool done, ErrorResult& aRv);

void ReadableStreamAddReadRequest(ReadableStream* aStream,
                                  ReadRequest* aReadRequest);
void ReadableStreamAddReadIntoRequest(ReadableStream* aStream,
                                      ReadIntoRequest* aReadIntoRequest);

MOZ_CAN_RUN_SCRIPT already_AddRefed<Promise> ReadableStreamCancel(
    JSContext* aCx, ReadableStream* aStream, JS::Handle<JS::Value> aError,
    ErrorResult& aRv);

already_AddRefed<ReadableStreamDefaultReader>
AcquireReadableStreamDefaultReader(ReadableStream* aStream, ErrorResult& aRv);

MOZ_CAN_RUN_SCRIPT already_AddRefed<ReadableStream> CreateReadableStream(
    JSContext* aCx, nsIGlobalObject* aGlobal,
    UnderlyingSourceAlgorithmsBase* aAlgorithms,
    mozilla::Maybe<double> aHighWaterMark, QueuingStrategySize* aSizeAlgorithm,
    ErrorResult& aRv);

bool ReadableStreamHasBYOBReader(ReadableStream* aStream);
bool ReadableStreamHasDefaultReader(ReadableStream* aStream);

MOZ_CAN_RUN_SCRIPT already_AddRefed<ReadableStream> CreateReadableByteStream(
    JSContext* aCx, nsIGlobalObject* aGlobal,
    UnderlyingSourceAlgorithmsBase* aAlgorithms, ErrorResult& aRv);

}  // namespace mozilla::dom

#endif  // mozilla_dom_ReadableStream_h