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

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

Index: third_party/WebKit/Source/core/dom/ScriptLoader.cpp
diff --git a/third_party/WebKit/Source/core/dom/ScriptLoader.cpp b/third_party/WebKit/Source/core/dom/ScriptLoader.cpp
index 7b3915aaac0eec2ae7e42d89ecbea6a1915a3734..06728b6cba34a67d9b0a2af2fdf7551ab27c2285 100644
--- a/third_party/WebKit/Source/core/dom/ScriptLoader.cpp
+++ b/third_party/WebKit/Source/core/dom/ScriptLoader.cpp
@@ -26,11 +26,13 @@
 
 #include "bindings/core/v8/ScriptController.h"
 #include "bindings/core/v8/ScriptSourceCode.h"
+#include "bindings/core/v8/ScriptState.h"
 #include "core/HTMLNames.h"
 #include "core/SVGNames.h"
 #include "core/dom/Document.h"
 #include "core/dom/DocumentParserTiming.h"
 #include "core/dom/IgnoreDestructiveWriteCountIncrementer.h"
+#include "core/dom/ModuleMap.h"
 #include "core/dom/ScriptLoaderClient.h"
 #include "core/dom/ScriptRunner.h"
 #include "core/dom/ScriptableDocumentParser.h"
@@ -60,6 +62,59 @@
 
 namespace blink {
 
+class ScriptElementModuleClient
+    : public GarbageCollectedFinalized<ScriptElementModuleClient>,
+      public ModuleMap::Client {
+  USING_GARBAGE_COLLECTED_MIXIN(ScriptElementModuleClient);
+
+ public:
+  static ScriptElementModuleClient* create(Element* element) {
+    return new ScriptElementModuleClient(element);
+  }
+  virtual ~ScriptElementModuleClient() = default;
+
+  DECLARE_TRACE();
+
+ private:
+  ScriptElementModuleClient(Element* element) : m_element(element) {}
+
+  // Implements ModuleMap::Client
+  void notifyFinished(ScriptModule) override;
+
+  Member<Element> m_element;
+};
+
+void ScriptElementModuleClient::notifyFinished(ScriptModule module) {
+  // The code below is entirely wrong o(｀ω´*)o
+  // TODO(kouhei? dominicc?): Fix this as a part of implementing "fetch a module
+  // script graph" algorithm.
+  if (module.isNull()) {
+    printf("ScriptElementModuleClient::notifyFinished: load has failed\n");
+    return;
+  }
+  printf("ScriptElementModuleClient::notifyFinished: load successful\n");
+
+  Document* contextDocument = m_element->document().contextDocument();
+  DCHECK(contextDocument);
+
+  // Below should belong to ScriptController.cpp
+  LocalFrame* frame = contextDocument->frame();
+  if (!frame)
+    return;
+  ScriptState* scriptState =
+      ScriptState::forMainWorld(contextDocument->frame());
+  DCHECK(scriptState);
+  ScriptState::Scope scope(scriptState);
+
+  CHECK(module.instantiate(scriptState));
+  module.evaluate(scriptState);
+}
+
+DEFINE_TRACE(ScriptElementModuleClient) {
+  visitor->trace(m_element);
+  ModuleMap::Client::trace(visitor);
+}
+
 ScriptLoader::ScriptLoader(Element* element,
                            bool parserInserted,
                            bool alreadyStarted,
@@ -90,6 +145,7 @@ ScriptLoader::~ScriptLoader() {}
 DEFINE_TRACE(ScriptLoader) {
   visitor->trace(m_element);
   visitor->trace(m_resource);
+  visitor->trace(m_elementModuleClient);
   visitor->trace(m_pendingScript);
   PendingScriptClient::trace(visitor);
 }
@@ -260,6 +316,7 @@ bool ScriptLoader::prepareScript(const TextPosition& scriptStartPosition,
     if (m_documentWriteIntervention ==
         DocumentWriteIntervention::FetchDocWrittenScriptDeferIdle)
       defer = FetchRequest::IdleLoad;
+
     if (!fetchScript(client->sourceAttributeValue(), defer))
       return false;
   }
@@ -335,10 +392,22 @@ bool ScriptLoader::fetchScript(const String& sourceUrl,
     return false;
 
   DCHECK(!m_resource);
+
   if (!stripLeadingAndTrailingHTMLSpaces(sourceUrl).isEmpty()) {
-    FetchRequest request(
-        ResourceRequest(elementDocument->completeURL(sourceUrl)),
-        m_element->localName());
+    KURL url = elementDocument->completeURL(sourceUrl);
+
+    if (RuntimeEnabledFeatures::moduleScriptsEnabled() &&
+        client()->typeAttributeValue() == "module") {
+      m_elementModuleClient = ScriptElementModuleClient::create(m_element);
+
+      // TODO(kouhei,dominicc): Below should trigger "fetch a module script
+      // graph", not "fetch a single module script" algorithm.
+      elementDocument->ensureModuleMap()->fetchSingle(url,
+                                                      m_elementModuleClient);
+      return true;
+    }
+
+    FetchRequest request(ResourceRequest(url), m_element->localName());
 
     CrossOriginAttributeValue crossOrigin = crossOriginAttributeValue(
         m_element->fastGetAttribute(HTMLNames::crossoriginAttr));