1 files changed, 225 insertions, 0 deletions
diff --git a/dom/encoding/TextDecoderStream.cpp b/dom/encoding/TextDecoderStream.cpp
new file mode 100644
index 0000000000..8f42553bd9
--- /dev/null
+++ b/dom/encoding/TextDecoderStream.cpp
@@ -0,0 +1,225 @@
+/* -*- 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/. */
+
+#include "mozilla/dom/TextDecoderStream.h"
+
+#include "nsContentUtils.h"
+#include "nsIGlobalObject.h"
+#include "mozilla/Encoding.h"
+#include "mozilla/dom/Promise.h"
+#include "mozilla/dom/TextDecoderStreamBinding.h"
+#include "mozilla/dom/TransformerCallbackHelpers.h"
+#include "mozilla/dom/TransformStream.h"
+#include "mozilla/dom/UnionTypes.h"
+
+namespace mozilla::dom {
+
+NS_IMPL_CYCLE_COLLECTION_WRAPPERCACHE(TextDecoderStream, mGlobal, mStream)
+NS_IMPL_CYCLE_COLLECTING_ADDREF(TextDecoderStream)
+NS_IMPL_CYCLE_COLLECTING_RELEASE(TextDecoderStream)
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(TextDecoderStream)
+  NS_WRAPPERCACHE_INTERFACE_MAP_ENTRY
+  NS_INTERFACE_MAP_ENTRY(nsISupports)
+NS_INTERFACE_MAP_END
+
+TextDecoderStream::TextDecoderStream(nsISupports* aGlobal,
+                                     const Encoding& aEncoding, bool aFatal,
+                                     bool aIgnoreBOM, TransformStream& aStream)
+    : mGlobal(aGlobal), mStream(&aStream) {
+  mFatal = aFatal;
+  mIgnoreBOM = aIgnoreBOM;
+  aEncoding.Name(mEncoding);
+  if (aIgnoreBOM) {
+    mDecoder = aEncoding.NewDecoderWithoutBOMHandling();
+  } else {
+    mDecoder = aEncoding.NewDecoderWithBOMRemoval();
+  }
+}
+
+TextDecoderStream::~TextDecoderStream() = default;
+
+JSObject* TextDecoderStream::WrapObject(JSContext* aCx,
+                                        JS::Handle<JSObject*> aGivenProto) {
+  return TextDecoderStream_Binding::Wrap(aCx, this, aGivenProto);
+}
+
+// TODO: This does not allow shared array buffers, just as the non-stream
+// TextDecoder/Encoder don't. (Bug 1561594)
+Span<const uint8_t> ExtractSpanFromBufferSource(
+    JSContext* aCx, JS::Handle<JS::Value> aBufferSource, ErrorResult& aRv) {
+  RootedUnion<OwningArrayBufferViewOrArrayBuffer> bufferSource(aCx);
+  if (!bufferSource.Init(aCx, aBufferSource)) {
+    aRv.MightThrowJSException();
+    aRv.StealExceptionFromJSContext(aCx);
+    return Span<const uint8_t>();
+  }
+
+  if (bufferSource.IsArrayBufferView()) {
+    ArrayBufferView& view = bufferSource.GetAsArrayBufferView();
+    view.ComputeState();
+    return Span(view.Data(), view.Length());
+  }
+
+  ArrayBuffer& buffer = bufferSource.GetAsArrayBuffer();
+  buffer.ComputeState();
+  return Span(buffer.Data(), buffer.Length());
+}
+
+class TextDecoderStreamAlgorithms : public TransformerAlgorithmsWrapper {
+  NS_DECL_ISUPPORTS_INHERITED
+  NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED(TextDecoderStreamAlgorithms,
+                                           TransformerAlgorithmsBase)
+
+  void SetDecoderStream(TextDecoderStream& aStream) {
+    mDecoderStream = &aStream;
+  }
+
+  // The common part of decode-and-enqueue and flush-and-enqueue.
+  // Note that the most of the decoding algorithm is implemented in
+  // mozilla::Decoder, and this is mainly about calling it properly.
+  // https://encoding.spec.whatwg.org/#decode-and-enqueue-a-chunk
+  MOZ_CAN_RUN_SCRIPT void DecodeSpanAndEnqueue(
+      JSContext* aCx, Span<const uint8_t> aInput, bool aFlush,
+      TransformStreamDefaultController& aController, ErrorResult& aRv) {
+    CheckedInt<nsAString::size_type> needed =
+        mDecoderStream->Decoder()->MaxUTF16BufferLength(aInput.Length());
+    if (!needed.isValid()) {
+      aRv.Throw(NS_ERROR_OUT_OF_MEMORY);
+      return;
+    }
+
+    nsString outDecodedString;
+    auto output = outDecodedString.GetMutableData(needed.value(), fallible);
+    if (!output) {
+      aRv.Throw(NS_ERROR_OUT_OF_MEMORY);
+      return;
+    }
+
+    mDecoderStream->DecodeNative(aInput, !aFlush, outDecodedString, aRv);
+    if (aRv.Failed()) {
+      return;
+    }
+
+    if (outDecodedString.Length()) {
+      // Step 4.2. If outputChunk is non-empty, then enqueue outputChunk in
+      // decoder’s transform.
+      JS::Rooted<JS::Value> outputChunk(aCx);
+      if (!xpc::NonVoidStringToJsval(aCx, outDecodedString, &outputChunk)) {
+        JS_ClearPendingException(aCx);
+        aRv.Throw(NS_ERROR_UNEXPECTED);
+        return;
+      }
+      aController.Enqueue(aCx, outputChunk, aRv);
+    }
+  }
+
+  // https://encoding.spec.whatwg.org/#dom-textdecoderstream
+  MOZ_CAN_RUN_SCRIPT void TransformCallbackImpl(
+      JS::Handle<JS::Value> aChunk,
+      TransformStreamDefaultController& aController,
+      ErrorResult& aRv) override {
+    // Step 7. Let transformAlgorithm be an algorithm which takes a chunk
+    // argument and runs the decode and enqueue a chunk algorithm with this and
+    // chunk.
+
+    // https://encoding.spec.whatwg.org/#decode-and-enqueue-a-chunk
+
+    AutoJSAPI jsapi;
+    if (!jsapi.Init(aController.GetParentObject())) {
+      aRv.ThrowUnknownError("Internal error");
+      return;
+    }
+    JSContext* cx = jsapi.cx();
+
+    // Step 1. Let bufferSource be the result of converting chunk to an
+    // [AllowShared] BufferSource.
+    // (But here we get a mozilla::Span instead)
+    Span<const uint8_t> input = ExtractSpanFromBufferSource(cx, aChunk, aRv);
+    if (aRv.Failed()) {
+      return;
+    }
+
+    DecodeSpanAndEnqueue(cx, input, false, aController, aRv);
+  }
+
+  // https://encoding.spec.whatwg.org/#dom-textdecoderstream
+  MOZ_CAN_RUN_SCRIPT void FlushCallbackImpl(
+      TransformStreamDefaultController& aController,
+      ErrorResult& aRv) override {
+    // Step 8. Let flushAlgorithm be an algorithm which takes no arguments and
+    // runs the flush and enqueue algorithm with this.
+
+    AutoJSAPI jsapi;
+    if (!jsapi.Init(aController.GetParentObject())) {
+      aRv.ThrowUnknownError("Internal error");
+      return;
+    }
+    JSContext* cx = jsapi.cx();
+
+    // https://encoding.spec.whatwg.org/#flush-and-enqueue
+    // (The flush and enqueue algorithm is basically a subset of decode and
+    // enqueue one, so let's reuse it)
+    DecodeSpanAndEnqueue(cx, Span<const uint8_t>(), true, aController, aRv);
+  }
+
+ private:
+  ~TextDecoderStreamAlgorithms() override = default;
+
+  RefPtr<TextDecoderStream> mDecoderStream;
+};
+
+NS_IMPL_CYCLE_COLLECTION_INHERITED(TextDecoderStreamAlgorithms,
+                                   TransformerAlgorithmsBase, mDecoderStream)
+NS_IMPL_ADDREF_INHERITED(TextDecoderStreamAlgorithms, TransformerAlgorithmsBase)
+NS_IMPL_RELEASE_INHERITED(TextDecoderStreamAlgorithms,
+                          TransformerAlgorithmsBase)
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(TextDecoderStreamAlgorithms)
+NS_INTERFACE_MAP_END_INHERITING(TransformerAlgorithmsBase)
+
+// https://encoding.spec.whatwg.org/#dom-textdecoderstream
+already_AddRefed<TextDecoderStream> TextDecoderStream::Constructor(
+    const GlobalObject& aGlobal, const nsAString& aLabel,
+    const TextDecoderOptions& aOptions, ErrorResult& aRv) {
+  // Step 1. Let encoding be the result of getting an encoding from label.
+  const Encoding* encoding = Encoding::ForLabelNoReplacement(aLabel);
+
+  // Step 2. If encoding is failure or replacement, then throw a RangeError
+  if (!encoding) {
+    NS_ConvertUTF16toUTF8 label(aLabel);
+    label.Trim(" \t\n\f\r");
+    aRv.ThrowRangeError<MSG_ENCODING_NOT_SUPPORTED>(label);
+    return nullptr;
+  }
+
+  // Step 3-6. (Done in the constructor)
+
+  // Step 7-8.
+  auto algorithms = MakeRefPtr<TextDecoderStreamAlgorithms>();
+
+  // Step 9-10.
+  RefPtr<TransformStream> transformStream =
+      TransformStream::CreateGeneric(aGlobal, *algorithms, aRv);
+  if (aRv.Failed()) {
+    return nullptr;
+  }
+
+  // Step 11. (Done in the constructor)
+  auto decoderStream = MakeRefPtr<TextDecoderStream>(
+      aGlobal.GetAsSupports(), *encoding, aOptions.mFatal, aOptions.mIgnoreBOM,
+      *transformStream);
+  algorithms->SetDecoderStream(*decoderStream);
+  return decoderStream.forget();
+}
+
+ReadableStream* TextDecoderStream::Readable() const {
+  return mStream->Readable();
+}
+
+WritableStream* TextDecoderStream::Writable() const {
+  return mStream->Writable();
+}
+
+}  // namespace mozilla::dom