Reland of Introduce ModulePendingScript

third_party/WebKit/Source/core/dom/ModulePendingScript.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/dom/ModulePendingScript.h"
+
+#include "core/dom/ScriptLoader.h"
+#include "core/frame/LocalFrame.h"
+
+namespace blink {
+
+ModulePendingScriptTreeClient::ModulePendingScriptTreeClient()
+    : module_script_(nullptr), pending_script_(nullptr) {}
+
+void ModulePendingScriptTreeClient::SetPendingScript(
+    ModulePendingScript* pending_script) {
+  DCHECK(!pending_script_);
+  pending_script_ = pending_script;
+
+  if (finished_) {
+    pending_script_->NotifyModuleTreeLoadFinished();
+  }
+}
+
+void ModulePendingScriptTreeClient::NotifyModuleTreeLoadFinished(
+    ModuleScript* module_script) {
+  DCHECK(!(module_script && module_script->InstantiationState() ==
+                                ModuleInstantiationState::kUninstantiated));
+  DCHECK(!finished_);
+  finished_ = true;
+  module_script_ = module_script;
+
+  if (pending_script_)
+    pending_script_->NotifyModuleTreeLoadFinished();
+}
+
+DEFINE_TRACE(ModulePendingScriptTreeClient) {
+  visitor->Trace(module_script_);
+  visitor->Trace(pending_script_);
+  ModuleTreeClient::Trace(visitor);
+}
+
+ModulePendingScript::ModulePendingScript(ScriptElementBase* element,
+                                         ModulePendingScriptTreeClient* client)
+    : PendingScript(element, TextPosition()), module_tree_client_(client) {
+  CHECK(this->GetElement());
+  DCHECK(module_tree_client_);
+  client->SetPendingScript(this);
+}
+
+ModulePendingScript::~ModulePendingScript() {}
+
+void ModulePendingScript::DisposeInternal() {
+  module_tree_client_ = nullptr;
+}
+
+DEFINE_TRACE(ModulePendingScript) {
+  visitor->Trace(module_tree_client_);
+  PendingScript::Trace(visitor);
+}
+
+void ModulePendingScript::NotifyModuleTreeLoadFinished() {
+  CHECK(!IsReady());
+  ready_ = true;
+
+  if (Client())
+    Client()->PendingScriptFinished(this);
+}
+
+Script* ModulePendingScript::GetSource(const KURL& document_url,
+                                       bool& error_occurred) const {
+  CHECK(IsReady());
+  error_occurred = ErrorOccurred();
+  return GetModuleScript();
+}
+
+bool ModulePendingScript::ErrorOccurred() const {
+  CHECK(IsReady());
+  return !GetModuleScript();
+}
+
+}  // namespace blink