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

third_party/WebKit/Source/core/loader/modulescript/ModuleScriptLoader.cpp

+// 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.
+
+#include "core/loader/modulescript/ModuleScriptLoader.h"
+
+#include "core/dom/Modulator.h"
+#include "core/dom/ModuleScript.h"
+#include "core/fetch/ResourceFetcher.h"
+#include "core/loader/modulescript/ModuleScriptLoaderClient.h"
+#include "core/loader/modulescript/ModuleScriptLoaderRegistry.h"
+#include "platform/network/mime/MIMETypeRegistry.h"
+
+namespace blink {
+
+ModuleScriptLoader::ModuleScriptLoader(const KURL& url,
+                                       const KURL& baseURL,
+                                       Modulator* modulator,
+                                       ModuleScriptLoaderRegistry* registry,
+                                       ModuleScriptLoaderClient* client)
+    : m_url(url),
+      m_baseURL(url),
+      m_modulator(modulator),
+      m_registry(registry),
+      m_client(client) {
+  DCHECK(modulator);
+  DCHECK(registry);
+  DCHECK(client);
+}
+
+ModuleScriptLoader::~ModuleScriptLoader() {}
+
+void ModuleScriptLoader::advanceState(ModuleScriptLoader::State newState) {
+  switch (m_state) {
+    case State::Initial:
+      DCHECK_EQ(newState, State::Fetching);
+      break;
+    case State::Fetching:
+      DCHECK_EQ(newState, State::Finished);
+      break;
+    case State::Finished:
+      NOTREACHED();
+      break;
+    default:
+      NOTREACHED();
+  }
+
+  m_state = newState;
+
+  if (m_state == State::Finished) {
+    m_registry->releaseFinishedLoader(this);
+    m_client->notifyFinishedNewSingleModule(m_moduleScript);
+  }
+}
+
+void ModuleScriptLoader::fetch(ResourceFetcher* fetcher) {
+  // Step 4. Set moduleMap[url] to "fetching".
+  advanceState(State::Fetching);
+
+  // Step 5. Let request be a new request whose url is url, destination is
+  // destination, type is "script", mode is "cors", credentials mode is
+  // credentials mode, cryptographic nonce metadata is cryptographic nonce,
+  // parser metadata is parser state, referrer is referrer, and client is
+  // fetch client settings object.
+  FetchRequest request(ResourceRequest(m_url), "module");
+
+  // Modules are always async
+  request.setDefer(FetchRequest::LazyLoad);
+  ScriptResource* resource = ScriptResource::fetch(request, fetcher);
+  setResource(resource);
+
+  // Step 6. If the caller specified custom steps to perform the fetch,
+  // perform
+  // them on request, setting the is top-level flag if the top-level module
+  // fetch flag is set. Return from this algorithm, and when the custom
+  // perform
+  // the fetch steps complete with response response, run the remaining steps.
+  // Otherwise, fetch request. Return from this algorithm, and run the
+  // remaining
+  // steps as part of the fetch's process response for the response response.
+  // Note: response is always CORS-same-origin.
+
+  // TODO(kouhei): I don't know what Step 6 means. ScriptLoader seems to
+  // ignore the step?
+}
+
+bool ModuleScriptLoader::wasModuleLoadSuccessful(Resource* resource) {
+  // Implements conditions in Step 7 of
+  // https://html.spec.whatwg.org/#fetch-a-single-module-script
+
+  // - response's type is "error"
+  if (resource->errorOccurred())
+    return false;
+
+  const auto& response = resource->response();
+  // - response's status is not an ok status
+  if (response.isHTTP() &&
+      (response.httpStatusCode() < 200 || response.httpStatusCode() >= 300)) {
+    return false;
+  }
+
+  // The result of extracting a MIME type from response's header list
+  // (ignoring parameters) is not a JavaScript MIME type
+  // Note: For historical reasons, fetching a classic script does not include
+  // MIME type checking. In contrast, module scripts will fail to load if they
+  // are not of a correct MIME type.
+  if (!MIMETypeRegistry::isSupportedJavaScriptMIMEType(response.mimeType()))
+    return false;
+
+  return true;
+}
+
+// ScriptResourceClient callback handler
+void ModuleScriptLoader::notifyFinished(Resource*) {
+  printf("notifyFinished!\n");
+
+  // Note: "conditions" referred in Step 7 is implemented in
+  // wasModuleLoadSuccessful().
+  // Step 7. If any of the following conditions are met, set moduleMap[url] to
+  // null, asynchronously complete this algorithm with null, and abort these
+  // steps.
+  if (!wasModuleLoadSuccessful(resource())) {
+    printf("notifyFinished but load was not successful\n");
+
+    advanceState(State::Finished);
+    setResource(nullptr);
+    return;
+  }
+
+  // Step 8. Let source text be the result of UTF-8 decoding response's body.
+  String script = resource()->script();
+  printf("fetched script: %s\n", script.utf8().data());
+
+  // Step 9. Let module script be the result of creating a module script given
+  // source text, module map settings object, response's url, cryptographic
+  // nonce, parser state, and credentials mode.
+
+  // TODO(kouhei): post a task to compile module?
+  ScriptModule record = m_modulator->compileModule(script, m_url.getString());
+  m_moduleScript = ModuleScript::create(record, m_baseURL);
+  advanceState(State::Finished);
+  setResource(nullptr);
+}
+
+DEFINE_TRACE(ModuleScriptLoader) {
+  visitor->trace(m_modulator);
+  visitor->trace(m_moduleScript);
+  visitor->trace(m_registry);
+  visitor->trace(m_client);
+  ResourceOwner<ScriptResource>::trace(visitor);
+}
+
+}  // namespace blink