dom/streams/TeeState.cpp

   1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim:set ts=2 sw=2 sts=2 et cindent: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #include "TeeState.h"
   8
   9 #include "ReadableStreamTee.h"
  10 #include "js/Value.h"
  11 #include "mozilla/HoldDropJSObjects.h"
  12 #include "mozilla/dom/ReadableStream.h"
  13 #include "mozilla/dom/Promise.h"
  14
  15 namespace mozilla::dom {
  16
  17 using namespace streams_abstract;
  18
  19 NS_IMPL_CYCLE_COLLECTION_WITH_JS_MEMBERS(TeeState,
  20                                          (mStream, mReader, mBranch1, mBranch2,
  21                                           mCancelPromise),
  22                                          (mReason1, mReason2))
  23 NS_IMPL_CYCLE_COLLECTING_ADDREF(TeeState)
  24 NS_IMPL_CYCLE_COLLECTING_RELEASE(TeeState)
  25 NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(TeeState)
  26   NS_INTERFACE_MAP_ENTRY(nsISupports)
  27 NS_INTERFACE_MAP_END
  28
  29 TeeState::TeeState(ReadableStream* aStream, bool aCloneForBranch2)
  30     : mStream(aStream),
  31       mReason1(JS::NullValue()),
  32       mReason2(JS::NullValue()),
  33       mCloneForBranch2(aCloneForBranch2) {
  34   mozilla::HoldJSObjects(this);
  35   MOZ_RELEASE_ASSERT(!aCloneForBranch2,
  36                      "cloneForBranch2 path is not implemented.");
  37 }
  38
  39 already_AddRefed<TeeState> TeeState::Create(ReadableStream* aStream,
  40                                             bool aCloneForBranch2,
  41                                             ErrorResult& aRv) {
  42   RefPtr<TeeState> teeState = new TeeState(aStream, aCloneForBranch2);
  43
  44   RefPtr<ReadableStreamDefaultReader> reader =
  45       AcquireReadableStreamDefaultReader(teeState->GetStream(), aRv);
  46   if (aRv.Failed()) {
  47     return nullptr;
  48   }
  49   teeState->SetReader(reader);
  50
  51   RefPtr<Promise> promise =
  52       Promise::CreateInfallible(teeState->GetStream()->GetParentObject());
  53   teeState->SetCancelPromise(promise);
  54
  55   return teeState.forget();
  56 }
  57
  58 // https://streams.spec.whatwg.org/#abstract-opdef-readablestreamdefaulttee
  59 // Pull Algorithm Steps:
  60 void TeeState::PullCallback(JSContext* aCx, nsIGlobalObject* aGlobal,
  61                             ErrorResult& aRv) {
  62   // Step 13.1: If reading is true,
  63   if (Reading()) {
  64     // Step 13.1.1: Set readAgain to true.
  65     SetReadAgain(true);
  66
  67     // Step 13.1.2: Return a promise resolved with undefined.
  68     // (The caller will create it if necessary)
  69     return;
  70   }
  71
  72   // Step 13.2: Set reading to true.
  73   SetReading(true);
  74
  75   // Step 13.3: Let readRequest be a read request with the following items:
  76   RefPtr<ReadRequest> readRequest =
  77       new ReadableStreamDefaultTeeReadRequest(this);
  78
  79   // Step 13.4: Perform ! ReadableStreamDefaultReaderRead(reader, readRequest).
  80   RefPtr<ReadableStreamGenericReader> reader = GetReader();
  81   ReadableStreamDefaultReaderRead(aCx, reader, readRequest, aRv);
  82
  83   // Step 13.5: Return a promise resolved with undefined.
  84   // (The caller will create it if necessary)
  85 }
  86
  87 }  // namespace mozilla::dom