[ES6 modules] Introduce ModuleScriptLoader

third_party/WebKit/Source/core/loader/modulescript/ModuleScriptLoader.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 ModuleScriptLoader_h
+#define ModuleScriptLoader_h
+
+#include "core/CoreExport.h"
+#include "core/loader/modulescript/ModuleScriptFetchRequest.h"
+#include "core/loader/resource/ScriptResource.h"
+#include "platform/heap/Handle.h"
+#include "platform/loader/fetch/ResourceLoaderOptions.h"
+#include "platform/loader/fetch/ResourceOwner.h"
+#include "platform/weborigin/KURL.h"
+#include "public/platform/WebURLRequest.h"
+
+namespace blink {
+
+class Modulator;
+class ModuleScript;
+class ModuleScriptLoaderClient;
+class ModuleScriptLoaderRegistry;
+enum class ModuleGraphLevel;
+
+// A ModuleScriptLoader is responsible for loading a new single ModuleScript.
+//
+// A ModuleScriptLoader constructs and emits FetchRequest to ResourceFetcher
+// (via ScriptResource::fetch). Then, it keeps track of the fetch progress by
+// being a ScriptResourceClient. Finally, it returns its client a compiled
+// ModuleScript.
+//
+// ModuleScriptLoader(s) should only be used via Modulator and its ModuleMap.
+class CORE_EXPORT ModuleScriptLoader final
+    : public GarbageCollectedFinalized<ModuleScriptLoader>,
+      public ResourceOwner<ScriptResource> {
+  WTF_MAKE_NONCOPYABLE(ModuleScriptLoader);
+  USING_GARBAGE_COLLECTED_MIXIN(ModuleScriptLoader);
+
+  enum class State {
+    Initial,
+    // FetchRequest is being processed, and ModuleScriptLoader hasn't
+    // notifyFinished().
+    Fetching,
+    // Finished successfully or w/ error.
+    Finished,
+  };
+
+ public:
+  static ModuleScriptLoader* create(Modulator* modulator,
+                                    ModuleScriptLoaderRegistry* registry,
+                                    ModuleScriptLoaderClient* client) {
+    return new ModuleScriptLoader(modulator, registry, client);
+  }
+
+  ~ModuleScriptLoader() override;
+
+  // Note: fetch may notify |m_client| synchronously or asynchronously.
+  void fetch(const ModuleScriptFetchRequest&,
+             ResourceFetcher*,
+             ModuleGraphLevel);
+
+  bool isInitialState() const { return m_state == State::Initial; }
+  bool hasFinished() const { return m_state == State::Finished; }
+
+  DECLARE_TRACE();
+
+ private:
+  ModuleScriptLoader(Modulator*,
+                     ModuleScriptLoaderRegistry*,
+                     ModuleScriptLoaderClient*);
+
+  static ModuleScript* createModuleScript(const String& sourceText,
+                                          const KURL&,
+                                          Modulator*,
+                                          const String& nonce,
+                                          ParserDisposition,
+                                          WebURLRequest::FetchCredentialsMode);
+
+  void advanceState(State newState);
+#if DCHECK_IS_ON()
+  static const char* stateToString(State);
+#endif
+
+  // Implements ScriptResourceClient
+  void notifyFinished(Resource*) override;
+  String debugName() const override { return "ModuleScriptLoader"; }
+
+  static bool wasModuleLoadSuccessful(Resource*);
+
+  Member<Modulator> m_modulator;
+  State m_state = State::Initial;
+  String m_nonce;
+  ParserDisposition m_parserState;
+  Member<ModuleScript> m_moduleScript;
+  Member<ModuleScriptLoaderRegistry> m_registry;
+  Member<ModuleScriptLoaderClient> m_client;
+#if DCHECK_IS_ON()
+  KURL m_url;
+#endif
+};
+
+}  // namespace blink
+
+#endif