[WIP Prototype] ES6 https://html.spec.whatwg.org/#fetch-a-single-module-script implementation

third_party/WebKit/Source/bindings/core/v8/ScriptModule.h

+// Copyright 2016 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.
+
+#ifndef ScriptModule_h
+#define ScriptModule_h
+
+#include "bindings/core/v8/ScriptState.h"
+#include "bindings/core/v8/SharedPersistent.h"
+#include "core/CoreExport.h"
+#include "wtf/Allocator.h"
+#include "wtf/text/WTFString.h"
+#include <v8.h>
+
+namespace blink {
+
+class CORE_EXPORT ScriptModule final {

[dominicc (has gone to gerrit), 2016/12/13 07:45:29]

Comments would be nice, so we don't have to dig through and read the V8
documentation.

+  DISALLOW_NEW_EXCEPT_PLACEMENT_NEW();
+
+ public:
+  static ScriptModule compile(v8::Isolate*,

[dominicc (has gone to gerrit), 2016/12/13 07:45:29]

I've gotten feedback from the bindings team in the past that they prefer to use
ScriptState. It might be worthwhile here because instantiate, evaluate, etc.
just become no-arg methods which removes the possibility of mixing modules
across isolates. (On the other hand, you have to check
ScriptState.contextIsValid; it's heavy; and you're not implementing a
"getIsolate" method or anything like that...)

+                              const String& source,
+                              const String& fileName);

[dominicc (has gone to gerrit), 2016/12/13 07:45:29]

It may make sense to use a parameter object instead of "fileName". IIRC everyone
ends up passing a ton of parameters--cacheability stuff, source maps, etc.--at
this point.

+
+  ScriptModule() {}
+  ScriptModule(const ScriptModule& module) : m_module(module.m_module) {}
+  ~ScriptModule();
+
+  bool instantiate(ScriptState*);
+  void evaluate(ScriptState*);
+
+  bool isNull() const { return m_module->isEmpty(); }
+
+ private:
+  ScriptModule(v8::Isolate*, v8::Local<v8::Module>);
+
+  RefPtr<SharedPersistent<v8::Module>> m_module;

[dominicc (has gone to gerrit), 2016/12/13 07:45:29]

Hmm, I guess this doesn't cause cycles because the document loses its module map
when detached? Is there any tricky way to get imports to happen after that?

It would be nice if traceWrappers was a bit more general and we could report not
only wrappers but V8 persistents when tracing
Document->ModuleMap->ScriptModules.

+};
+
+}  // namespace blink
+
+#endif  // ScriptModule_h