Implement ReadableStream as a V8 extra

Source/core/streams/ScriptReadableStreamController.cpp

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "config.h"
+#include "core/streams/ScriptReadableStreamController.h"
+
+#include "bindings/core/v8/ToV8.h"
+
+namespace blink {
+
+// TODO probably need the asserts from the spec here
+
+// NOTE: the normal graph is ScriptReadableStreamController -> ScriptReadableStream -> V8 ReadableStream object ->
+// V8 underlying source object -> ScriptUnderlyingSource -> ScriptReadableStream -> ScriptReadableStreamController ....
+// However once you call close() or error() methods of ScriptReadableStreamController, the
+// ScriptReadableStreamController -> ScriptReadableStream link is broken by m_stream.clear().
+
+ScriptReadableStreamController::ScriptReadableStreamController(ScriptValue stream) : m_stream(stream)
+{
+}
+
+void ScriptReadableStreamController::close()
+{
+    if (m_stream.isEmpty())
+        return;
+
+    ScriptState::Scope scope(m_stream.scriptState());
+
+    auto func = m_stream.scriptState()->getFromExtrasExports("CloseReadableStream").v8Value().As<v8::Function>();
+
+    auto undefined = v8::Undefined(m_stream.isolate());
+    v8::Local<v8::Value> args[] = { m_stream.v8Value() };
+    auto result = func->Call(undefined, 1, args);
+
+    // TODO crash if result is empty (i.e. an exception)
+
+    m_stream.clear();
+}
+
+double ScriptReadableStreamController::desiredSize() const
+{
+    if (m_stream.isEmpty())
+        return 0;
+
+    ScriptState::Scope scope(m_stream.scriptState());
+
+    auto func = m_stream.scriptState()->getFromExtrasExports("GetReadableStreamDesiredSize").v8Value().As<v8::Function>();
+
+    auto undefined = v8::Undefined(m_stream.isolate());
+    v8::Local<v8::Value> args[] = { m_stream.v8Value() };
+    auto result = func->Call(undefined, 1, args);
+
+    return result.As<v8::Number>()->Value();
+}
+
+template<typename ChunkType>
+void ScriptReadableStreamController::enqueue(ChunkType chunk) const
+{
+    if (m_stream.isEmpty())
+        return;
+
+    ScriptState::Scope scope(m_stream.scriptState());
+
+    auto func = m_stream.scriptState()->getFromExtrasExports("EnqueueInReadableStream").v8Value().As<v8::Function>();
+
+    auto chunkForV8 = toV8(chunk, m_stream.context()->Global(), m_stream.isolate());
+    auto undefined = v8::Undefined(m_stream.isolate());
+    v8::Local<v8::Value> args[] = { m_stream.v8Value(), chunkForV8 };
+    auto result = func->Call(undefined, 2, args);
+
+    // TODO crash if result is empty (i.e. an exception)
+}
+
+template<typename ErrorType>
+void ScriptReadableStreamController::error(ErrorType e)
+{
+    if (m_stream.isEmpty())
+        return;
+
+    ScriptState::Scope scope(m_stream.scriptState());
+
+    auto func = m_stream.scriptState()->getFromExtrasExports("ErrorReadableStream").v8Value().As<v8::Function>();
+
+    auto errorForV8 = toV8(e, m_stream.context()->Global(), m_stream.isolate());
+    auto undefined = v8::Undefined(m_stream.isolate());
+    v8::Local<v8::Value> args[] = { m_stream.v8Value(), errorForV8 };
+    auto result = func->Call(undefined, 2, args);
+
+    // TODO crash if result is empty (i.e. an exception)
+
+    m_stream.clear();
+}
+
+} // namespace blink