protoc-gen-oracall: remove String hack, use golang/protobuf#1260

protoc-gen-oracall/protoc_gen_oracall.go

@@ -17,6 +17,10 @@ import (
 	oracall "github.com/tgulacsi/oracall/lib"
 	"google.golang.org/protobuf/compiler/protogen"
 	"google.golang.org/protobuf/proto"
+	"google.golang.org/protobuf/reflect/protoreflect"
+	"google.golang.org/protobuf/reflect/protoregistry"
+	// "google.golang.org/protobuf/types/descriptorpb"
+	"google.golang.org/protobuf/types/dynamicpb"
 	"google.golang.org/protobuf/types/pluginpb"
 )
 
@@ -43,55 +47,52 @@ func Main() error {
 		panic(err)
 	}
 
+	// https://github.com/golang/protobuf/issues/1260
+	// The type information for all extensions is in the source files,
+	// so we need to extract them into a dynamically created protoregistry.Types.
+	extTypes := new(protoregistry.Types)
+	for _, file := range plugin.Files {
+		if err := registerAllExtensions(extTypes, file.Desc); err != nil {
+			return fmt.Errorf("registerAllExtensions: %w", err)
+		}
+	}
+
 	// Protoc passes a slice of File structs for us to process
 	for _, file := range plugin.Files {
 		// log.Printf("? %q", file.GoImportPath.String())
 		if strings.HasPrefix(file.GoImportPath.String(), `"google.golang.org/`) {
 			log.Println("skip", file.GoImportPath.String())
 			continue
 		}
-		// var messageOption, fieldOption *protogen.Message
-		// for _, e := range file.Extensions {
-		// 	switch e.Extendee.Desc.FullName() {
-		// 	case "google.protobuf.MessageOptions":
-		// 		messageOption = e.Extendee
-		// 	case "google.protobuf.FieldOptions":
-		// 		fieldOption = e.Extendee
-		// 	}
-		// }
 
 		// Time to generate code...!
 		var buf bytes.Buffer
 
 		// 2. Write the package name
 		fmt.Fprintf(&buf, "// Code generated by protoc-gen-oracall. DO NOT EDIT!\n\npackage %s\n\n", file.GoPackageName)
 
-		for _, msg := range file.Proto.MessageType {
-			// FIXME[tgulacs]: this is a hack, but I couldn't find out how to get the extensions' options' values
-			optS := msg.Options.String()
-			opts, err := parseOption(optS)
+		for _, msg := range file.Messages {
+			objectType, err := getCustomOption(extTypes, msg.Desc.Options(), "oracall_object_type")
 			if err != nil {
-				return fmt.Errorf("parse %q: %w", optS, err)
+				return err
 			}
-			objectType := opts["objects.oracall_object_type"]
+			msgName := msg.Desc.Name()
 			fmt.Fprintf(&buf, "\n// %q=%q\nfunc(%s) ObjecTypeName() string { return %q }\n",
-				*msg.Name, objectType,
-				*msg.Name, objectType,
+				msgName, objectType,
+				msgName, objectType,
 			)
-			fmt.Fprintf(&buf, "func (%s) FieldTypeName(f string) string{\n\tswitch f {\n", msg.GetName())
-			for _, f := range msg.Field {
-				optS := f.Options.String()
-				opts, err := parseOption(optS)
+			fmt.Fprintf(&buf, "func (%s) FieldTypeName(f string) string{\n\tswitch f {\n", msg.Desc.Name())
+			fields := msg.Desc.Fields()
+			for i := range fields.Len() {
+				f := fields.Get(i)
+				fieldName := string(f.Name())
+				fieldType, err := getCustomOption(extTypes, f.Options(), "oracall_field_type")
 				if err != nil {
-					return fmt.Errorf("parse %q: %w", optS, err)
-				}
-				fieldType := opts["objects.oracall_field_type"]
-				if fieldType == "" {
-					log.Printf("opts=%q fields=%+v", optS, opts)
+					return err
 				}
 				fmt.Fprintf(&buf, "\t\t// %q.%q = %q\n\t\tcase %q, %q: return %q\n",
-					*msg.Name, oracall.CamelCase(f.GetName()), fieldType,
-					f.GetName(), oracall.CamelCase(f.GetName()), fieldType,
+					msgName, oracall.CamelCase(fieldName), fieldType,
+					fieldName, oracall.CamelCase(fieldName), fieldType,
 				)
 			}
 			fmt.Fprintf(&buf, "}\n\treturn \"\"\n}\n")
@@ -121,16 +122,61 @@ func Main() error {
 	return err
 }
 
-// parseOption parses the [option.name]:"value" stringified option.
-func parseOption(s string) (map[string]string, error) {
-	k, v, ok := strings.Cut(s, ":")
-	if !ok {
-		return nil, fmt.Errorf("no : in %q", s)
+func getCustomOption(extTypes *protoregistry.Types, options protoreflect.ProtoMessage, name string) (protoreflect.Value, error) {
+	var value protoreflect.Value
+	err := iterCustomOptions(extTypes, options, func(fd protoreflect.FieldDescriptor, v protoreflect.Value) error {
+		if string(fd.Name()) == name {
+			value = v
+		}
+		return nil
+	})
+	return value, err
+}
+func iterCustomOptions(extTypes *protoregistry.Types, options protoreflect.ProtoMessage, f func(protoreflect.FieldDescriptor, protoreflect.Value) error) error {
+	// The MessageOptions as provided by protoc does not know about
+	// dynamically created extensions, so they are left as unknown fields.
+	// We round-trip marshal and unmarshal the options with
+	// a dynamically created resolver that does know about extensions at runtime.
+	// options := msg.Desc.Options().(*descriptorpb.MessageOptions)
+	b, err := proto.Marshal(options)
+	if err != nil {
+		return fmt.Errorf("Marshal(%#v): %w", options, err)
+	}
+	options.(interface{ Reset() }).Reset()
+	err = proto.UnmarshalOptions{Resolver: extTypes}.Unmarshal(b, options)
+	if err != nil {
+		return fmt.Errorf("Unmarshal: %w", err)
 	}
-	if w, err := strconv.Unquote(v); err != nil {
-		return nil, fmt.Errorf("unquote %q: %w", v, err)
-	} else {
-		v = w
+
+	// Use protobuf reflection to iterate over all the extension fields,
+	// looking for the ones that we are interested in.
+	options.ProtoReflect().Range(func(fd protoreflect.FieldDescriptor, v protoreflect.Value) bool {
+		if !fd.IsExtension() {
+			return true
+		}
+		if err = f(fd, v); err != nil {
+			return false
+		}
+		// Make use of fd and v based on their reflective properties.
+		return true
+	})
+	return err
+}
+
+// https://github.com/golang/protobuf/issues/1260
+func registerAllExtensions(extTypes *protoregistry.Types, descs interface {
+	Messages() protoreflect.MessageDescriptors
+	Extensions() protoreflect.ExtensionDescriptors
+}) error {
+	mds := descs.Messages()
+	for i := 0; i < mds.Len(); i++ {
+		registerAllExtensions(extTypes, mds.Get(i))
+	}
+	xds := descs.Extensions()
+	for i := 0; i < xds.Len(); i++ {
+		if err := extTypes.RegisterExtension(dynamicpb.NewExtensionType(xds.Get(i))); err != nil {
+			return err
+		}
 	}
-	return map[string]string{strings.Trim(k, "[]"): v}, nil
+	return nil
 }