bindings: Add C++ versions of WebIDL types and generalize NativeValueTraits.

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

Index: third_party/WebKit/Source/bindings/core/v8/IDLTypes.h
diff --git a/third_party/WebKit/Source/bindings/core/v8/IDLTypes.h b/third_party/WebKit/Source/bindings/core/v8/IDLTypes.h
new file mode 100644
index 0000000000000000000000000000000000000000..69a8c853949fd60ba13d48fbf998da0b84f3324d
--- /dev/null
+++ b/third_party/WebKit/Source/bindings/core/v8/IDLTypes.h
@@ -0,0 +1,92 @@
+// Copyright (c) 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 IDLTypes_h
+#define IDLTypes_h
+
+#include <type_traits>
+#include "bindings/core/v8/IDLTypesBase.h"
+#include "bindings/core/v8/NativeValueTraits.h"
+#include "bindings/core/v8/V8Binding.h"
+#include "core/CoreExport.h"
+#include "platform/heap/Handle.h"
+#include "wtf/TypeTraits.h"
+#include "wtf/text/WTFString.h"
+
+namespace blink {
+
+class ScriptPromise;
+
+// Boolean
+struct CORE_EXPORT IDLBoolean final : public IDLBaseHelper<bool> {};
+
+// Integers
+struct CORE_EXPORT IDLByte final : public IDLBaseHelper<int8_t> {};
+struct CORE_EXPORT IDLOctet final : public IDLBaseHelper<uint8_t> {};
+struct CORE_EXPORT IDLShort final : public IDLBaseHelper<int16_t> {};
+struct CORE_EXPORT IDLUnsignedShort final : public IDLBaseHelper<uint16_t> {};
+struct CORE_EXPORT IDLLong final : public IDLBaseHelper<int32_t> {};
+struct CORE_EXPORT IDLUnsignedLong final : public IDLBaseHelper<uint32_t> {};
+struct CORE_EXPORT IDLLongLong final : public IDLBaseHelper<int64_t> {};
+struct CORE_EXPORT IDLUnsignedLongLong final : public IDLBaseHelper<uint64_t> {
+};
+
+// Strings
+struct CORE_EXPORT IDLByteString final : public IDLBaseHelper<String> {};
+struct CORE_EXPORT IDLString final : public IDLBaseHelper<String> {};
+struct CORE_EXPORT IDLUSVString final : public IDLBaseHelper<String> {};
+
+// Double
+struct CORE_EXPORT IDLDouble final : public IDLBaseHelper<double> {};
+struct CORE_EXPORT IDLUnrestrictedDouble final : public IDLBaseHelper<double> {
+};
+
+// Float
+struct CORE_EXPORT IDLFloat final : public IDLBaseHelper<float> {};
+struct CORE_EXPORT IDLUnrestrictedFloat final : public IDLBaseHelper<float> {};
+
+struct CORE_EXPORT IDLDate final : public IDLBaseHelper<double> {};
+
+// Promise
+struct CORE_EXPORT IDLPromise final : public IDLBaseHelper<ScriptPromise> {};
+
+// Template helpers for type introspection
+struct IDLTypesHelper {

[haraken, 2017/03/06 12:56:32]

I'd prefer not introducing IDLTypesHelper though. It is essentially a syntax
sugar for WTF::IsGarbageCollectedType::value. Maybe can we improve the template
in WTF instead?

+  STATIC_ONLY(IDLTypesHelper);
+
+  // Whether a type needs to be wrapped in Member<> (i.e. Oilpan-based types).
+  template <typename T>
+  struct MaybeWrapped {

[haraken, 2017/03/06 12:56:32]

MaybeWrapped => NeedsMember ?

[Yuki, 2017/03/08 10:14:22]

rakuco, you seems overlooking this comment.

This comment somewhat makes sense because we often use the term "wrap" for V8
wrapper object (for a Blink DOM object).  It's a bit confusing.

NeedsMember looks like that it returns a boolean value, so we may like another
name.

What about MaybeMember for example?

I'm okay to change the name in https://crrev.com/2732093003

+    using ImplType = typename std::
+        conditional<WTF::IsGarbageCollectedType<T>::value, Member<T>, T>::type;
+  };
+
+  // Whether a type should be wrapped in Vector<> or HeapVector<>. HeapVector<>
+  // is used for Oilpan-based types as well as IDL unions and dictionaries
+  // (which have V8TypeOf).
+  template <typename T>
+  struct NeedsHeapVector {
+    static const bool value = WTF::IsGarbageCollectedType<T>::value ||
+                              std::is_class<typename V8TypeOf<T>::Type>::value;

[haraken, 2017/03/06 12:56:32]

What is std::is_class<typename V8TypeOf<T>::Type>::value doing?

+  };
+};
+
+// Sequence
+template <typename T>
+struct CORE_EXPORT IDLSequence final : public IDLBase {
+ private:
+  using CppType = typename NativeValueTraits<T>::ImplType;
+  using MaybeWrappedCppType =
+      typename IDLTypesHelper::MaybeWrapped<CppType>::ImplType;
+
+ public:
+  using ImplType =
+      typename std::conditional<IDLTypesHelper::NeedsHeapVector<CppType>::value,
+                                HeapVector<MaybeWrappedCppType>,
+                                Vector<MaybeWrappedCppType>>::type;
+};
+
+}  // namespace blink
+
+#endif  // IDLTypes_h