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

third_party/WebKit/Source/bindings/core/v8/ScriptModule.h

 // 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.
 
 #ifndef ScriptModule_h
 #define ScriptModule_h
 
+#include <v8.h>
 #include "bindings/core/v8/ScriptState.h"
 #include "bindings/core/v8/SharedPersistent.h"
 #include "core/CoreExport.h"
 #include "wtf/Allocator.h"
+#include "wtf/HashTableDeletedValueType.h"
+#include "wtf/HashTraits.h"
+#include "wtf/Vector.h"
 #include "wtf/text/WTFString.h"
-#include <v8.h>
 
 namespace blink {
 
+class ScriptModuleIdentifier;
+class ScriptState;
+
+// ScriptModule wraps a handle to a v8::Module for use in core.
+//
+// Using ScriptModules needs a ScriptState and its scope to operate in. You
+// should always provide the same ScriptState and not try to reuse ScriptModules
+// across different contexts.
+// Currently all ScriptModule users can easily access its context Modulator, so
+// we use it to fill ScriptState in.
 class CORE_EXPORT ScriptModule final {
   DISALLOW_NEW_EXCEPT_PLACEMENT_NEW();
 
  public:
   static ScriptModule compile(v8::Isolate*,
                               const String& source,
                               const String& fileName);
 
+  // TODO(kouhei): Remove copy ctor
   ScriptModule() {}
-  ScriptModule(const ScriptModule& module) : m_module(module.m_module) {}
+  ScriptModule(const ScriptModule&) = default;
+  ScriptModule(ScriptModule&&) = default;
+  ScriptModule& operator=(ScriptModule&&) = default;
   ~ScriptModule();
 
-  bool instantiate(ScriptState*);
+  ScriptValue instantiate(ScriptState*);
   void evaluate(ScriptState*);
 
+  Vector<String> moduleRequests(ScriptState*);
+
+  bool isNull() const { return !m_module || m_module->isEmpty(); }
+  ScriptModuleIdentifier identifier();
+
+ private:
+  friend class ScriptModuleIdentifier;
+  ScriptModule(v8::Isolate*, v8::Local<v8::Module>);
+
+  static v8::MaybeLocal<v8::Module> resolveModuleCallback(
+      v8::Local<v8::Context>,
+      v8::Local<v8::String> specifier,
+      v8::Local<v8::Module> referrer);
+
+  RefPtr<SharedPersistent<v8::Module>> m_module;
+  unsigned m_identityHash = 0;
+};
+
+// TODO(kouhei): Split header/cpp
+// TODO(kouhei): PeekType which can be construct w/ only v8::Local
+class ScriptModuleIdentifier {
+ public:
+  class Hash;
+
+  ScriptModuleIdentifier() = default;
+  ScriptModuleIdentifier(const ScriptModuleIdentifier& id)
+      : m_module(id.m_module), m_identityHash(id.m_identityHash) {}
+  ScriptModuleIdentifier(WTF::HashTableDeletedValueType)
+      : m_module(WTF::HashTableDeletedValue) {}
+  /*
+  FIXME(kouhei): need move op=
+  ScriptModuleIdentifier(ScriptModuleIdentifier&& id)
+      : m_module(std::move(id.m_module)), m_identityHash(id.m_identityHash) {}
+      */
+  ~ScriptModuleIdentifier() = default;
+
+  bool isHashTableDeletedValue() const {
+    return m_module.isHashTableDeletedValue();
+  }
+
+  bool operator==(const blink::ScriptModuleIdentifier& rhs) const {
+    if (m_module.isHashTableDeletedValue() &&
+        rhs.m_module.isHashTableDeletedValue())
+      return true;
+
+    blink::SharedPersistent<v8::Module>* lhsp = m_module.get();
+    blink::SharedPersistent<v8::Module>* rhsp = rhs.m_module.get();
+    if (lhsp == rhsp)
+      return true;
+    if (!lhsp || !rhsp)
+      return false;
+    return *lhsp == *rhsp;
+  }
+
   bool isNull() const { return m_module->isEmpty(); }
 
  private:
-  ScriptModule(v8::Isolate*, v8::Local<v8::Module>);
+  friend class ScriptModule;
+  friend struct ScriptModuleIdentifierHash;
 
+  explicit ScriptModuleIdentifier(
+      const RefPtr<SharedPersistent<v8::Module>>& module,
+      unsigned identityHash)
+      : m_module(module), m_identityHash(identityHash) {}
+
+  // TODO(kouhei): Make ScriptModule move-only and make this ScopedPersistent.
   RefPtr<SharedPersistent<v8::Module>> m_module;
+  unsigned m_identityHash = 0;
+};
+
+struct ScriptModuleIdentifierHash {
+  STATIC_ONLY(ScriptModuleIdentifierHash);
+
+ public:
+  static unsigned hash(const blink::ScriptModuleIdentifier& key) {
+    return static_cast<unsigned>(key.m_identityHash);
+  }
+
+  static bool equal(const blink::ScriptModuleIdentifier& a,
+                    const blink::ScriptModuleIdentifier& b) {
+    return a == b;
+  }
+
+  static constexpr bool safeToCompareToEmptyOrDeleted = true;
 };
 
 }  // namespace blink
 
+namespace WTF {
+
+template <>
+struct DefaultHash<blink::ScriptModuleIdentifier> {
+  using Hash = blink::ScriptModuleIdentifierHash;
+};
+
+template <>
+struct HashTraits<blink::ScriptModuleIdentifier>
+    : public SimpleClassHashTraits<blink::ScriptModuleIdentifier> {};
+
+}  // namespace WTF
+
 #endif  // ScriptModule_h