[ES6 modules] Introduce ScriptModuleResolverImpl

third_party/WebKit/Source/core/dom/ScriptModuleResolverImpl.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/ScriptModuleResolverImpl.h"
+
+#include "bindings/core/v8/ScriptModule.h"
+#include "core/dom/Modulator.h"
+#include "core/dom/ModuleScript.h"
+
+namespace blink {
+
+void ScriptModuleResolverImpl::registerModuleScript(
+    ModuleScript* moduleScript) {
+#if DCHECK_IS_ON()
+  DVLOG(1) << "ScriptModuleResolverImpl::registerModuleScript(url=\""

[kinuko, 2017/04/05 14:05:00]

I don't think we need to wrap DVLOG with DCHECK_IS_ON

+           << moduleScript->baseURL().getString()
+           << "\", hash=" << ScriptModuleHash::hash(moduleScript->record())
+           << ")";
+#endif
+
+  DCHECK(moduleScript);
+  DCHECK(!moduleScript->record().isNull());
+  auto result =
+      m_recordToModuleScriptMap.set(moduleScript->record(), moduleScript);
+  DCHECK(result.isNewEntry);
+}
+
+ScriptModule ScriptModuleResolverImpl::resolve(const String& specifier,
+                                               const ScriptModule& referrer,
+                                               ExceptionState& exceptionState) {
+// https://html.spec.whatwg.org/#hostresolveimportedmodule(referencingmodule,-specifier)
+#if DCHECK_IS_ON()

[domenic, 2017/04/05 07:07:45]

You may want to add a second line pointing out this is an implementation of
https://html.spec.whatwg.org/commit-snapshots/f8e75a974ed9185e5b462bc5b2dfb32...
specifically.

[kouhei (in TOK), 2017/04/06 05:34:18]

Done.

+  DVLOG(1) << "ScriptModuleResolverImpl::resolve(specifier=\"" << specifier
+           << ", referrer.hash=" << ScriptModuleHash::hash(referrer) << ")";
+#endif
+
+  // Step 1. Let referencing module script be referencingModule.[[HostDefined]].
+  const auto it = m_recordToModuleScriptMap.find(referrer);
+  CHECK_NE(it, m_recordToModuleScriptMap.end())

[kinuko, 2017/04/05 14:05:00]

Do we need CHECK (not DCHECK) here?

[kouhei (in TOK), 2017/04/06 05:34:18]

hiroshige and I try to use CHECK wherever possible in script code to demystify
crash reports.

+      << "Failed to find referrer ModuleScript corresponding to the record";
+  ModuleScript* referrerModule = it->value;
+
+  // Step 2. Let moduleMap be referencing module script's settings object's
+  // module map. Note: Blink finds out "module script's settings object"
+  // (Modulator) from context where HostResolveImportedModule was called.

[kouhei (in TOK), 2017/04/05 06:30:11]

+domenic FYI

+
+  // Step 3. Let url be the result of resolving a module specifier given
+  // referencing module script and specifier. If the result is failure, then
+  // throw a TypeError exception and abort these steps.
+  KURL url =
+      Modulator::resolveModuleSpecifier(specifier, referrerModule->baseURL());
+  if (!url.isValid()) {
+    exceptionState.throwTypeError("Failed to resolve module specifier '" +
+                                  specifier + "'");
+    return ScriptModule();
+  }
+
+  // Step 4. Let resolved module script be moduleMap[url]. If no such entry
+  // exists, or if resolved module script is null or "fetching", then throw a
+  // TypeError exception and abort these steps.
+  ModuleScript* moduleScript = m_modulator->getFetchedModuleScript(url);
+  if (!moduleScript) {
+    exceptionState.throwTypeError(
+        "Failed to load module script for module specifier '" + specifier +
+        "'");
+    return ScriptModule();
+  }
+
+  // Step 5. If resolved module script's instantiation state is "errored", then
+  // throw resolved module script's instantiation error.
+  if (moduleScript->instantiationState() == ModuleInstantiationState::Errored) {
+    // TODO(kouhei): Implement this path once
+    // https://codereview.chromium.org/2782403002/ landed.
+    NOTIMPLEMENTED();
+    return ScriptModule();
+  }
+
+  // Step 6. Assert: resolved module script's instantiation state is
+  // "instantiated" (and thus its module record is not null).
+  // TODO(kouhei): Enable below check once once
+  // https://codereview.chromium.org/2782403002/ landed.
+  // CHECK_EQ(moduleScript->instantiationState(),
+  // ModuleInstantiationState::Instantiated);
+
+  // Step 7. Return resolved module script's module record.
+  return moduleScript->record();
+}
+
+DEFINE_TRACE(ScriptModuleResolverImpl) {
+  ScriptModuleResolver::trace(visitor);
+  visitor->trace(m_recordToModuleScriptMap);
+  visitor->trace(m_modulator);
+}
+
+}  // namespace blink