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

third_party/WebKit/Source/core/dom/ModulatorImpl.cpp

+// Copyright 2017 The Chromium Authors. All rights reserved.

[dominicc (has gone to gerrit), 2017/01/11 03:23:48]

I like how straightforward the implementation of this class is; it forwards to
the right places and ties the right bits of state together.

+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "core/dom/ModulatorImpl.h"
+
+#include "core/dom/Document.h"
+#include "core/dom/ModuleMap.h"
+#include "core/dom/ModuleScript.h"
+#include "core/dom/ScriptModuleResolverImpl.h"
+#include "core/dom/TaskRunnerHelper.h"
+#include "core/fetch/ResourceFetcher.h"
+#include "core/loader/modulescript/ModuleScriptLoaderRegistry.h"
+#include "core/loader/modulescript/ModuleTreeLinkerRegistry.h"
+
+namespace blink {
+
+ModulatorImpl* ModulatorImpl::create(RefPtr<ScriptState> scriptState,
+                                     Document& document) {
+  return new ModulatorImpl(
+      std::move(scriptState),
+      TaskRunnerHelper::get(TaskType::Networking, &document),
+      document.fetcher());
+}
+
+ModulatorImpl::ModulatorImpl(RefPtr<ScriptState> scriptState,
+                             WebTaskRunner* taskRunner,
+                             ResourceFetcher* fetcher)
+    : m_scriptState(std::move(scriptState)),
+      m_taskRunner(taskRunner->clone()),
+      m_fetcher(fetcher),
+      m_map(ModuleMap::create(this)),
+      m_loaderRegistry(ModuleScriptLoaderRegistry::create()),
+      m_treeLinkerRegistry(ModuleTreeLinkerRegistry::create()),
+      m_scriptModuleResolver(ScriptModuleResolverImpl::create(this)) {
+  DCHECK(m_scriptState);
+  DCHECK(m_fetcher);
+}
+
+ModulatorImpl::~ModulatorImpl() {}
+
+void ModulatorImpl::fetchTree(const KURL& url,
+                              const KURL& baseURL,
+                              ModuleTreeClient* client) {
+  // Step 1. Perform the internal module script graph fetching procedure given
+  // url, settings object, destination, cryptographic nonce, parser state,
+  // credentials mode, settings object, a new empty list, "client", and with the
+  // top-level module fetch flag set. If the caller of this algorithm specified
+  // custom perform the fetch steps, pass those along as well.
+  HashSet<KURL> emptyAncestorList;
+  m_treeLinkerRegistry->fetch(url, baseURL, emptyAncestorList, this, client);
+
+  // Step 2. When the internal module script graph fetching procedure
+  // asynchronously completes with result, asynchronously complete this
+  // algorithm with result.
+}
+
+void ModulatorImpl::fetchSingle(const KURL& url,
+                                const KURL& baseURL,
+                                SingleModuleClient* client) {
+  m_map->retrieveAndFetchIfNeeded(url, baseURL, client);
+}
+
+void ModulatorImpl::fetchNewSingleModule(const KURL& url,
+                                         const KURL& baseURL,
+                                         ModuleScriptLoaderClient* client) {
+  m_loaderRegistry->fetch(url, baseURL, this, m_fetcher.get(), client);
+}
+
+ModuleScript* ModulatorImpl::retrieveFetchedModuleScript(const KURL& url) {
+  return m_map->retrieveFetchedModuleScript(url);
+}
+
+ScriptModule ModulatorImpl::compileModule(const String& script,
+                                          const String& urlStr) {
+  v8::Isolate* isolate = V8PerIsolateData::mainThreadIsolate();
+  v8::HandleScope handleScope(isolate);

[dominicc (has gone to gerrit), 2017/01/11 06:57:15]

ScriptState::Scope has a handle scope; do you need this one? Ditto below.

[kouhei (in TOK), 2017/01/17 05:26:13]

Done.

+
+  ScriptState::Scope scope(m_scriptState.get());
+  return ScriptModule::compile(isolate, script, urlStr);
+}
+
+bool ModulatorImpl::instantiateModule(ScriptModule scriptModule) {
+  v8::Isolate* isolate = V8PerIsolateData::mainThreadIsolate();
+  v8::HandleScope handleScope(isolate);
+
+  ScriptState::Scope scope(m_scriptState.get());
+  return scriptModule.instantiate(m_scriptState.get());
+}
+
+Vector<String> ModulatorImpl::moduleRequestsFromScriptModule(
+    ScriptModule scriptModule) {
+  v8::Isolate* isolate = V8PerIsolateData::mainThreadIsolate();
+  v8::HandleScope handleScope(isolate);
+
+  ScriptState::Scope scope(m_scriptState.get());
+  return scriptModule.moduleRequests(m_scriptState.get());
+}
+
+void ModulatorImpl::executeModule(ScriptModule scriptModule) {
+  v8::Isolate* isolate = V8PerIsolateData::mainThreadIsolate();
+  v8::HandleScope handleScope(isolate);
+
+  ScriptState::Scope scope(m_scriptState.get());
+
+  v8::MicrotasksScope microtasksScope(isolate,
+                                      v8::MicrotasksScope::kRunMicrotasks);
+  scriptModule.evaluate(m_scriptState.get());

[dominicc (has gone to gerrit), 2017/01/11 06:57:15]

Wonder if this API should take ExceptionState?

[kouhei (in TOK), 2017/01/17 05:26:13]

I'm not aware of the case when it can throw exception atm.
Will add once we have such case.

+}
+
+DEFINE_TRACE(ModulatorImpl) {
+  visitor->trace(m_map);
+  visitor->trace(m_fetcher);
+  visitor->trace(m_loaderRegistry);
+  visitor->trace(m_treeLinkerRegistry);
+  visitor->trace(m_scriptModuleResolver);
+}
+
+}  // namespace blink