[mojo-bindings] Support reuse of native enum classes

mojo/public/tools/bindings/generators/mojom_cpp_generator.py

Index: mojo/public/tools/bindings/generators/mojom_cpp_generator.py
diff --git a/mojo/public/tools/bindings/generators/mojom_cpp_generator.py b/mojo/public/tools/bindings/generators/mojom_cpp_generator.py
index f9d2bd0713310de550524fed81605fe0fae22b74..ba9ec1671342291bbb888713394fdbdd167f490f 100644
--- a/mojo/public/tools/bindings/generators/mojom_cpp_generator.py
+++ b/mojo/public/tools/bindings/generators/mojom_cpp_generator.py
@@ -61,11 +61,17 @@ def DefaultValue(field):
 def NamespaceToArray(namespace):
   return namespace.split(".") if namespace else []
 
+def IsNativeStructKind(kind):
+  return mojom.IsStructKind(kind) and kind.native_only
+
+def IsNativeEnumKind(kind):
+  return mojom.IsEnumKind(kind) and kind.native_only
+
 def GetNamePartsForKind(kind, add_same_module_namespaces, internal):
   def MapKindName_(kind):
     if not internal:
       return kind.name
-    if mojom.IsStructKind(kind) and kind.native_only:
+    if IsNativeStructKind(kind):
       return "mojo::Array_Data<uint8_t>"
     if (mojom.IsStructKind(kind) or mojom.IsUnionKind(kind) or
         mojom.IsInterfaceKind(kind) or mojom.IsEnumKind(kind)):
@@ -102,16 +108,13 @@ def IsTypemappedKind(kind):
   return hasattr(kind, "name") and \
       GetFullMojomNameForKind(kind) in _current_typemap
 
-def IsNativeOnlyKind(kind):
-  return mojom.IsStructKind(kind) and kind.native_only
-
 def GetNativeTypeName(typemapped_kind):
   return _current_typemap[GetFullMojomNameForKind(typemapped_kind)]["typename"]
 
 def DoesKindSupportEquality(kind):
   if IsTypemappedKind(kind):
     return False
-  if mojom.IsStructKind(kind) and kind.native_only:
+  if IsNativeStructKind(kind):
     return False
   if mojom.IsArrayKind(kind):
     return DoesKindSupportEquality(kind.kind)
@@ -120,7 +123,7 @@ def DoesKindSupportEquality(kind):
   return True
 
 def GetCppType(kind):
-  if mojom.IsStructKind(kind) and kind.native_only:
+  if IsNativeStructKind(kind):
     # A native-only type is just a blob of bytes.
     return "mojo::internal::Array_Data<uint8_t>*"
   if mojom.IsArrayKind(kind):
@@ -152,16 +155,18 @@ def GetCppPodType(kind):
   return _kind_to_cpp_type[kind]
 
 def GetCppArrayArgWrapperType(kind):
-  if mojom.IsStructKind(kind) and kind.native_only:
+  if IsNativeStructKind(kind):
     if IsTypemappedKind(kind):
       return GetNativeTypeName(kind)
-    else:
-      # Without a relevant typemap to apply, a native-only struct can only be
-      # exposed as a blob of bytes.
-      return "mojo::Array<uint8_t>"
-  if IsTypemappedKind(kind):
+    # Without a relevant typemap to apply, a native-only struct can only be
+    # exposed as a blob of bytes.
+    return "mojo::Array<uint8_t>"
+  if mojom.IsStructKind(kind) and IsTypemappedKind(kind):
     raise Exception(
         "Cannot serialize containers of non-native typemapped structs yet!")
+  if IsNativeEnumKind(kind):
+    assert IsTypemappedKind(kind)
+    return GetNativeTypeName(kind)
   if mojom.IsEnumKind(kind):
     return GetNameForKind(kind)
   if mojom.IsStructKind(kind) or mojom.IsUnionKind(kind):
@@ -195,10 +200,12 @@ def GetCppArrayArgWrapperType(kind):
   return _kind_to_cpp_type[kind]
 
 def GetCppResultWrapperType(kind):
-  if IsTypemappedKind(kind):
+  if mojom.IsStructKind(kind) and IsTypemappedKind(kind):
     return "const %s&" % GetNativeTypeName(kind)
-  if mojom.IsStructKind(kind) and kind.native_only:
+  if IsNativeStructKind(kind):
     return "mojo::Array<uint8_t>"
+  if IsNativeEnumKind(kind):
+    return GetNativeTypeName(kind)
   if mojom.IsEnumKind(kind):
     return GetNameForKind(kind)
   if mojom.IsStructKind(kind) or mojom.IsUnionKind(kind):
@@ -239,7 +246,8 @@ def GetCppResultWrapperType(kind):
 def GetCppWrapperType(kind):
   if IsTypemappedKind(kind):
     return GetNativeTypeName(kind)
-  if mojom.IsStructKind(kind) and kind.native_only:
+  assert not IsNativeEnumKind(kind)
+  if IsNativeStructKind(kind):
     return "mojo::Array<uint8_t>"
   if mojom.IsEnumKind(kind):
     return GetNameForKind(kind)
@@ -273,10 +281,13 @@ def GetCppWrapperType(kind):
   return _kind_to_cpp_type[kind]
 
 def GetCppConstWrapperType(kind):
-  if IsTypemappedKind(kind):
+  if mojom.IsStructKind(kind) and IsTypemappedKind(kind):
     return "const %s&" % GetNativeTypeName(kind)
-  if mojom.IsStructKind(kind) and kind.native_only:
+  if IsNativeStructKind(kind):
     return "mojo::Array<uint8_t>"
+  if IsNativeEnumKind(kind):
+    assert IsTypemappedKind(kind)
+    return GetNativeTypeName(kind)
   if mojom.IsStructKind(kind) or mojom.IsUnionKind(kind):
     return "%sPtr" % GetNameForKind(kind)
   if mojom.IsArrayKind(kind):
@@ -311,7 +322,7 @@ def GetCppConstWrapperType(kind):
   return _kind_to_cpp_type[kind]
 
 def GetCppFieldType(kind):
-  if mojom.IsStructKind(kind) and kind.native_only:
+  if IsNativeStructKind(kind):
     return "mojo::internal::ArrayPointer<uint8_t>"
   if mojom.IsStructKind(kind):
     return ("mojo::internal::StructPointer<%s>" %
@@ -477,7 +488,8 @@ class Generator(generator.Generator):
     "is_enum_kind": mojom.IsEnumKind,
     "is_integral_kind": mojom.IsIntegralKind,
     "is_move_only_kind": mojom.IsMoveOnlyKind,
-    "is_native_only_kind": IsNativeOnlyKind,
+    "is_native_enum_kind": IsNativeEnumKind,
+    "is_native_struct_kind": IsNativeStructKind,
     "is_any_handle_kind": mojom.IsAnyHandleKind,
     "is_interface_kind": mojom.IsInterfaceKind,
     "is_interface_request_kind": mojom.IsInterfaceRequestKind,