[ES6 modules] Introduce ModuleMap

third_party/WebKit/Source/core/dom/ModuleMap.h

+// Copyright 2017 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 ModuleMap_h
+#define ModuleMap_h
+
+#include "core/CoreExport.h"
+#include "platform/heap/Handle.h"
+#include "platform/weborigin/KURL.h"
+#include "platform/weborigin/KURLHash.h"
+#include "wtf/HashMap.h"
+
+namespace blink {
+
+class Modulator;
+class ModuleScript;
+class ModuleScriptFetchRequest;
+class SingleModuleClient;
+enum class ModuleGraphLevel;
+
+// A ModuleMap implements "module map" spec.
+// https://html.spec.whatwg.org/#module-map
+class CORE_EXPORT ModuleMap final : public GarbageCollected<ModuleMap> {
+  WTF_MAKE_NONCOPYABLE(ModuleMap);
+  class Entry;
+  class LoaderHost;
+
+ public:
+  static ModuleMap* create(Modulator* modulator) {
+    return new ModuleMap(modulator);
+  }
+  DECLARE_TRACE();
+
+  void retrieveAndFetchIfNeeded(const ModuleScriptFetchRequest&,

[hiroshige, 2017/02/22 01:21:31]

This directly corresponds to "fetch a single module script".
So how about naming this as e.g. fetchSingleModuleScript() that directly
corresponds to the spec name?

Also referring to the "fetch a single module script" spec in the comment here or
at the top of ModuleMap declaration will be helpful.

[kouhei (in TOK), 2017/02/22 07:08:04]

Done.

+                                ModuleGraphLevel,
+                                SingleModuleClient*);
+  ModuleScript* retrieveFetchedModuleScript(const KURL&);

[hiroshige, 2017/02/22 01:21:31]

Can this be const method?

Also this looks like a getter method, and I feel 'retrieve' like something with
side effects.
(At least we should name functions that causes actual loading (e.g.
retrieveAndFetchIfNeeded()) and those not (e.g. retrieveFetchedModuleScript())
differently)

[kouhei (in TOK), 2017/02/22 07:08:04]

Added const

+
+  Modulator* modulator() { return m_modulator; }
+
+ private:
+  explicit ModuleMap(Modulator*);
+  ModuleMap() = delete;
+
+  using MapImpl = HeapHashMap<KURL, Member<Entry>>;
+
+  // A module map is a map of absolute URLs to map entry.
+  MapImpl m_map;
+
+  Member<Modulator> m_modulator;
+};
+
+}  // namespace blink
+
+#endif