[ES6 modules] Introduce ModuleTreeLinker

third_party/WebKit/Source/core/loader/modulescript/ModuleTreeLinkerRegistry.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/ModuleTreeLinkerRegistry.h"
+
+#include "core/loader/modulescript/ModuleTreeLinker.h"
+#include "platform/weborigin/KURL.h"
+#include "platform/weborigin/KURLHash.h"
+
+namespace blink {
+
+DEFINE_TRACE(ModuleTreeLinkerRegistry) {
+  visitor->Trace(active_tree_linkers_);
+}
+
+ModuleTreeLinker* ModuleTreeLinkerRegistry::Fetch(
+    const ModuleScriptFetchRequest& request,
+    const AncestorList& ancestor_list,
+    ModuleGraphLevel level,
+    Modulator* modulator,
+    ModuleTreeClient* client) {
+  ModuleTreeLinker* fetcher = ModuleTreeLinker::Fetch(
+      request, ancestor_list, level, modulator, this, client);
+  DCHECK(fetcher->IsFetching());
+  active_tree_linkers_.insert(fetcher);
+  return fetcher;
+}
+
+void ModuleTreeLinkerRegistry::ReleaseFinishedFetcher(
+    ModuleTreeLinker* fetcher) {
+  DCHECK(fetcher->HasFinished());
+
+  auto it = active_tree_linkers_.Find(fetcher);
+  DCHECK_NE(it, active_tree_linkers_.end());
+  active_tree_linkers_.erase(it);
+}
+
+}  // namespace blink