[ES6 modules] Introduce ScriptModuleResolverImpl

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

Index: third_party/WebKit/Source/core/dom/ScriptModuleResolverImpl.cpp
diff --git a/third_party/WebKit/Source/core/dom/ScriptModuleResolverImpl.cpp b/third_party/WebKit/Source/core/dom/ScriptModuleResolverImpl.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..297890d7a1fa776b1a23a7381a665b51ffee1240
--- /dev/null
+++ b/third_party/WebKit/Source/core/dom/ScriptModuleResolverImpl.cpp
@@ -0,0 +1,94 @@
+// 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* module_script) {
+  DVLOG(1) << "ScriptModuleResolverImpl::registerModuleScript(url=\""
+           << module_script->BaseURL().GetString()
+           << "\", hash=" << ScriptModuleHash::GetHash(module_script->Record())
+           << ")";
+
+  DCHECK(module_script);
+  DCHECK(!module_script->Record().IsNull());
+  auto result =
+      record_to_module_script_map_.Set(module_script->Record(), module_script);
+  DCHECK(result.is_new_entry);
+}
+
+ScriptModule ScriptModuleResolverImpl::Resolve(
+    const String& specifier,
+    const ScriptModule& referrer,
+    ExceptionState& exception_state) {
+  // https://html.spec.whatwg.org/commit-snapshots/f8e75a974ed9185e5b462bc5b2dfb32034bd1145#hostresolveimportedmodule(referencingmodule,-specifier)
+  DVLOG(1) << "ScriptModuleResolverImpl::resolve(specifier=\"" << specifier
+           << ", referrer.hash=" << ScriptModuleHash::GetHash(referrer) << ")";
+
+  // Step 1. Let referencing module script be referencingModule.[[HostDefined]].
+  const auto it = record_to_module_script_map_.Find(referrer);
+  CHECK_NE(it, record_to_module_script_map_.end())
+      << "Failed to find referrer ModuleScript corresponding to the record";
+  ModuleScript* referrer_module = 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.
+
+  // 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, referrer_module->BaseURL());
+  if (!url.IsValid()) {
+    exception_state.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* module_script = modulator_->GetFetchedModuleScript(url);
+  if (!module_script) {
+    exception_state.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 (module_script->InstantiationState() ==
+      ModuleInstantiationState::kErrored) {
+    // 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 module_script->Record();
+}
+
+DEFINE_TRACE(ScriptModuleResolverImpl) {
+  ScriptModuleResolver::Trace(visitor);
+  visitor->Trace(record_to_module_script_map_);
+  visitor->Trace(modulator_);
+}
+
+}  // namespace blink