[ES6 modules] Introduce ModuleMap

third_party/WebKit/Source/core/dom/Modulator.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 Modulator_h
 #define Modulator_h
 
 #include "core/CoreExport.h"
 #include "platform/heap/Handle.h"
 #include "platform/weborigin/KURL.h"
 
 namespace blink {
 
 class LocalFrame;
+class ModuleScript;
+class ModuleScriptFetchRequest;
+class ModuleScriptLoaderClient;
+class ScriptModuleResolver;
+class WebTaskRunner;
+
+// A SingleModuleClient is notified when single module script node (node as in a
+// module tree graph) load is complete and its corresponding entry is created in
+// module map.
+class SingleModuleClient : public GarbageCollectedMixin {
+ public:
+  virtual void notifyModuleLoadFinished(ModuleScript*) = 0;
+};
+
+// spec: "top-level module fetch flag"
+// https://html.spec.whatwg.org/multipage/webappapis.html#fetching-scripts-is-top-level
+enum class ModuleGraphLevel { TopLevelModuleFetch, DependentModuleFetch };
 
 // A Modulator is an interface for "environment settings object" concept for
 // module scripts.
 // https://html.spec.whatwg.org/#environment-settings-object
 //
 // A Modulator also serves as an entry point for various module spec algorithms.
 class CORE_EXPORT Modulator : public GarbageCollectedMixin {
  public:
   static Modulator* from(LocalFrame*);
 
+  virtual ScriptModuleResolver* scriptModuleResolver() = 0;
+  virtual WebTaskRunner* taskRunner() = 0;
+
   // https://html.spec.whatwg.org/#resolve-a-module-specifier
   static KURL resolveModuleSpecifier(const String& moduleRequest,
                                      const KURL& baseURL);
+
+ private:
+  friend class ModuleMap;
+
+  // Fetches a single module script.
+  // This is triggered from fetchSingle() implementation (which is in ModuleMap)
+  // if the cached entry doesn't exist.
+  // The client can be notified either synchronously or asynchronously.
+  virtual void fetchNewSingleModule(const ModuleScriptFetchRequest&,
+                                    ModuleGraphLevel,
+                                    ModuleScriptLoaderClient*) = 0;
 };
 
 }  // namespace blink
 
 #endif