Add a utility class to call stream methods implemented with v8 extras.

third_party/WebKit/Source/bindings/core/v8/ReadableStreamOperations.cpp

Index: third_party/WebKit/Source/bindings/core/v8/ReadableStreamOperations.cpp
diff --git a/third_party/WebKit/Source/bindings/core/v8/ReadableStreamOperations.cpp b/third_party/WebKit/Source/bindings/core/v8/ReadableStreamOperations.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..62fe081e46c185c1f005ace8c669229d85d38ce3
--- /dev/null
+++ b/third_party/WebKit/Source/bindings/core/v8/ReadableStreamOperations.cpp
@@ -0,0 +1,104 @@
+// 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 "bindings/core/v8/ReadableStreamOperations.h"
+
+#include "bindings/core/v8/ExceptionState.h"
+#include "bindings/core/v8/ScriptState.h"
+
+namespace blink {
+
+namespace {
+
+v8::MaybeLocal<v8::Value> call(ScriptState* scriptState, const char* name, size_t numArgs, v8::Local<v8::Value>* args)
+{
+    v8::Isolate* isolate = scriptState->isolate();
+    v8::Local<v8::Context> context = scriptState->context();
+    v8::Local<v8::Value> undefined = v8::Undefined(isolate);
+    v8::Local<v8::Value> functionValue = scriptState->getFromExtrasExports(name).v8Value();
+    ASSERT(!functionValue.IsEmpty() && functionValue->IsFunction());
+    v8::Local<v8::Function> function = functionValue.As<v8::Function>();
+    return function->Call(context, undefined, numArgs, args);
+}
+
+template <size_t N>
+v8::MaybeLocal<v8::Value> call(ScriptState* scriptState, const char* name, v8::Local<v8::Value>(&args)[N])
+{
+    return call(scriptState, name, N, args);
+}
+
+} // namespace
+
+ScriptValue ReadableStreamOperations::getReader(ScriptState* scriptState, v8::Local<v8::Value> stream, ExceptionState& es)
+{
+    ASSERT(isReadableStream(scriptState, stream));
+
+    v8::TryCatch block(scriptState->isolate());
+    v8::Local<v8::Value> args[] = { stream };
+    ScriptValue result(scriptState, call(scriptState, "AcquireReadableStreamReader", args));
+    if (block.HasCaught())
+        es.rethrowV8Exception(block.Exception());
+    return result;
+}
+
+bool ReadableStreamOperations::isReadableStream(ScriptState* scriptState, v8::Local<v8::Value> value)
+{
+    if (!value->IsObject())
+        return false;
+
+    v8::Local<v8::Value> args[] = { value };
+    v8::Local<v8::Value> resultValue;
+    bool ok = call(scriptState, "IsReadableStream", args).ToLocal(&resultValue);

[haraken, 2015/12/04 01:41:05]

Can we use v8CallOrBoolean? The same comment for other ToLocals. Basically we
prefer using v8CallXXX macros than ToLocal.

[yhirano, 2015/12/04 05:55:47]

Fixed.

I talked with bashi@ and added v8Call(MaybeLocal<T>, Local<T>&) for just calling
ToLocal, because passing around a TryCatch block just for assertion is tiresome.

[bashi, 2015/12/04 06:48:53]

In this specific case, we may just want to do:

resultValue = v8CallOrCrash(call(...));

because we just ASSERT() here and provide no additional information.

+    ASSERT_UNUSED(ok, ok);
+    return resultValue->ToBoolean()->Value();
+}
+
+bool ReadableStreamOperations::isDisturbed(ScriptState* scriptState, v8::Local<v8::Value> stream)
+{
+    ASSERT(isReadableStream(scriptState, stream));
+
+    v8::Local<v8::Value> args[] = { stream };
+    v8::Local<v8::Value> resultValue;
+    bool ok = call(scriptState, "IsReadableStreamDisturbed", args).ToLocal(&resultValue);
+    ASSERT_UNUSED(ok, ok);
+    return resultValue->ToBoolean()->Value();
+}
+
+bool ReadableStreamOperations::isLocked(ScriptState* scriptState, v8::Local<v8::Value> stream)
+{
+    ASSERT(isReadableStream(scriptState, stream));
+
+    v8::Local<v8::Value> resultValue;
+    v8::Local<v8::Value> args[] = { stream };
+    bool ok = call(scriptState, "IsReadableStreamLocked", args).ToLocal(&resultValue);
+    ASSERT_UNUSED(ok, ok);
+    return resultValue->ToBoolean()->Value();
+}
+
+bool ReadableStreamOperations::isReadableStreamReader(ScriptState* scriptState, v8::Local<v8::Value> value)
+{
+    if (!value->IsObject())
+        return false;
+
+    v8::Local<v8::Value> resultValue;
+    v8::Local<v8::Value> args[] = { value };
+    bool ok = call(scriptState, "IsReadableStreamReader", args).ToLocal(&resultValue);
+    ASSERT_UNUSED(ok, ok);
+    return resultValue->ToBoolean()->Value();
+}
+
+ScriptPromise ReadableStreamOperations::read(ScriptState* scriptState, v8::Local<v8::Value> reader)
+{
+    ASSERT(isReadableStreamReader(scriptState, reader));
+
+    v8::Local<v8::Value> resultValue;
+    v8::Local<v8::Value> args[] = { reader };
+    bool ok = call(scriptState, "ReadFromReadableStreamReader", args).ToLocal(&resultValue);
+    ASSERT_UNUSED(ok, ok);
+    return ScriptPromise::cast(scriptState, resultValue);
+}
+
+} // namespace blink
+