wire_format.cc: Refactor Message and Group handling into a helper func

PiperOrigin-RevId: 632191495

src/google/protobuf/wire_format.cc

@@ -766,6 +766,44 @@ struct WireFormat::MessageSetParser {
   const Reflection* reflection;
 };
 
+static const char* HandleMessage(Message* msg, const char* ptr,
+                                 internal::ParseContext* ctx, uint64_t tag,
+                                 const Reflection* reflection,
+                                 const FieldDescriptor* field) {
+  Message* sub_message;
+  if (field->is_repeated()) {
+    sub_message = reflection->AddMessage(msg, field, ctx->data().factory);
+  } else {
+    sub_message = reflection->MutableMessage(msg, field, ctx->data().factory);
+  }
+
+  if (WireFormatLite::GetTagWireType(tag) ==
+      WireFormatLite::WIRETYPE_START_GROUP) {
+    return ctx->ParseGroup(sub_message, ptr, tag);
+  } else {
+    ABSL_DCHECK(WireFormatLite::GetTagWireType(tag) ==
+                WireFormatLite::WIRETYPE_LENGTH_DELIMITED);
+  }
+
+  ptr = ctx->ParseMessage(sub_message, ptr);
+
+  // For map entries, if the value is an unknown enum we have to push it
+  // into the unknown field set and remove it from the list.
+  if (ptr != nullptr && field->is_map()) {
+    auto* value_field = field->message_type()->map_value();
+    auto* enum_type = value_field->enum_type();
+    if (enum_type != nullptr &&
+        !internal::cpp::HasPreservingUnknownEnumSemantics(value_field) &&
+        enum_type->FindValueByNumber(sub_message->GetReflection()->GetEnumValue(
+            *sub_message, value_field)) == nullptr) {
+      reflection->MutableUnknownFields(msg)->AddLengthDelimited(
+          field->number(), sub_message->SerializeAsString());
+      reflection->RemoveLast(msg, field);
+    }
+  }
+  return ptr;
+}
+
 const char* WireFormat::_InternalParse(Message* msg, const char* ptr,
                                        internal::ParseContext* ctx) {
   const Descriptor* descriptor = msg->GetDescriptor();
@@ -995,46 +1033,9 @@ const char* WireFormat::_InternalParseAndMergeField(
       return ptr;
     }
 
-    case FieldDescriptor::TYPE_GROUP: {
-      Message* sub_message;
-      if (field->is_repeated()) {
-        sub_message = reflection->AddMessage(msg, field, ctx->data().factory);
-      } else {
-        sub_message =
-            reflection->MutableMessage(msg, field, ctx->data().factory);
-      }
-
-      return ctx->ParseGroup(sub_message, ptr, tag);
-    }
-
-    case FieldDescriptor::TYPE_MESSAGE: {
-      Message* sub_message;
-      if (field->is_repeated()) {
-        sub_message = reflection->AddMessage(msg, field, ctx->data().factory);
-      } else {
-        sub_message =
-            reflection->MutableMessage(msg, field, ctx->data().factory);
-      }
-      ptr = ctx->ParseMessage(sub_message, ptr);
-
-      // For map entries, if the value is an unknown enum we have to push it
-      // into the unknown field set and remove it from the list.
-      if (ptr != nullptr && field->is_map()) {
-        auto* value_field = field->message_type()->map_value();
-        auto* enum_type = value_field->enum_type();
-        if (enum_type != nullptr &&
-            !internal::cpp::HasPreservingUnknownEnumSemantics(value_field) &&
-            enum_type->FindValueByNumber(
-                sub_message->GetReflection()->GetEnumValue(
-                    *sub_message, value_field)) == nullptr) {
-          reflection->MutableUnknownFields(msg)->AddLengthDelimited(
-              field->number(), sub_message->SerializeAsString());
-          reflection->RemoveLast(msg, field);
-        }
-      }
-
-      return ptr;
-    }
+    case FieldDescriptor::TYPE_MESSAGE:
+    case FieldDescriptor::TYPE_GROUP:
+      return HandleMessage(msg, ptr, ctx, tag, reflection, field);
   }
 
   // GCC 8 complains about control reaching end of non-void function here.