snapshot of https://github.com/grpc/grpc-go.git (master, 2026-09-15; blobs > 131072B omitted)

cmd/protoc-gen-go-grpc/grpc.go

@@ -0,0 +1,513 @@
+/*
+ *
+ * Copyright 2020 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package main
+
+import (
+	"fmt"
+	"strconv"
+	"strings"
+
+	"google.golang.org/protobuf/compiler/protogen"
+	"google.golang.org/protobuf/reflect/protoreflect"
+	"google.golang.org/protobuf/types/descriptorpb"
+)
+
+const (
+	contextPackage = protogen.GoImportPath("context")
+	grpcPackage    = protogen.GoImportPath("google.golang.org/grpc")
+	codesPackage   = protogen.GoImportPath("google.golang.org/grpc/codes")
+	statusPackage  = protogen.GoImportPath("google.golang.org/grpc/status")
+)
+
+type serviceGenerateHelperInterface interface {
+	formatFullMethodSymbol(service *protogen.Service, method *protogen.Method) string
+	genFullMethods(g *protogen.GeneratedFile, service *protogen.Service)
+	generateClientStruct(g *protogen.GeneratedFile, clientName string)
+	generateNewClientDefinitions(g *protogen.GeneratedFile, service *protogen.Service, clientName string)
+	generateUnimplementedServerType(gen *protogen.Plugin, file *protogen.File, g *protogen.GeneratedFile, service *protogen.Service)
+	generateServerFunctions(gen *protogen.Plugin, file *protogen.File, g *protogen.GeneratedFile, service *protogen.Service, serverType string, serviceDescVar string)
+	formatHandlerFuncName(service *protogen.Service, hname string) string
+}
+
+type serviceGenerateHelper struct{}
+
+func (serviceGenerateHelper) formatFullMethodSymbol(service *protogen.Service, method *protogen.Method) string {
+	return fmt.Sprintf("%s_%s_FullMethodName", service.GoName, method.GoName)
+}
+
+func (serviceGenerateHelper) genFullMethods(g *protogen.GeneratedFile, service *protogen.Service) {
+	if len(service.Methods) == 0 {
+		return
+	}
+
+	g.P("const (")
+	for _, method := range service.Methods {
+		fmSymbol := helper.formatFullMethodSymbol(service, method)
+		fmName := fmt.Sprintf("/%s/%s", service.Desc.FullName(), method.Desc.Name())
+		g.P(fmSymbol, ` = "`, fmName, `"`)
+	}
+	g.P(")")
+	g.P()
+}
+
+func (serviceGenerateHelper) generateClientStruct(g *protogen.GeneratedFile, clientName string) {
+	g.P("type ", unexport(clientName), " struct {")
+	g.P("cc ", grpcPackage.Ident("ClientConnInterface"))
+	g.P("}")
+	g.P()
+}
+
+func (serviceGenerateHelper) generateNewClientDefinitions(g *protogen.GeneratedFile, _ *protogen.Service, clientName string) {
+	g.P("return &", unexport(clientName), "{cc}")
+}
+
+func (serviceGenerateHelper) generateUnimplementedServerType(_ *protogen.Plugin, _ *protogen.File, g *protogen.GeneratedFile, service *protogen.Service) {
+	serverType := service.GoName + "Server"
+	mustOrShould := "must"
+	if !*requireUnimplemented {
+		mustOrShould = "should"
+	}
+	// Server Unimplemented struct for forward compatibility.
+	g.P("// Unimplemented", serverType, " ", mustOrShould, " be embedded to have")
+	g.P("// forward compatible implementations.")
+	g.P("//")
+	g.P("// NOTE: this should be embedded by value instead of pointer to avoid a nil")
+	g.P("// pointer dereference when methods are called.")
+	g.P("type Unimplemented", serverType, " struct {}")
+	g.P()
+	for _, method := range service.Methods {
+		nilArg := ""
+		if !method.Desc.IsStreamingClient() && !method.Desc.IsStreamingServer() {
+			nilArg = "nil,"
+		}
+		g.P("func (Unimplemented", serverType, ") ", serverSignature(g, method), "{")
+		g.P("return ", nilArg, statusPackage.Ident("Error"), "(", codesPackage.Ident("Unimplemented"), `, "method `, method.GoName, ` not implemented")`)
+		g.P("}")
+	}
+	if *requireUnimplemented {
+		g.P("func (Unimplemented", serverType, ") mustEmbedUnimplemented", serverType, "() {}")
+	}
+	g.P("func (Unimplemented", serverType, ") testEmbeddedByValue() {}")
+	g.P()
+}
+
+func (serviceGenerateHelper) generateServerFunctions(gen *protogen.Plugin, file *protogen.File, g *protogen.GeneratedFile, service *protogen.Service, serverType string, serviceDescVar string) {
+	// Server handler implementations.
+	handlerNames := make([]string, 0, len(service.Methods))
+	for _, method := range service.Methods {
+		hname := genServerMethod(gen, file, g, method, func(hname string) string {
+			return hname
+		})
+		handlerNames = append(handlerNames, hname)
+	}
+	genServiceDesc(file, g, serviceDescVar, serverType, service, handlerNames)
+}
+
+func (serviceGenerateHelper) formatHandlerFuncName(_ *protogen.Service, hname string) string {
+	return hname
+}
+
+var helper serviceGenerateHelperInterface = serviceGenerateHelper{}
+
+// FileDescriptorProto.package field number
+const fileDescriptorProtoPackageFieldNumber = 2
+
+// FileDescriptorProto.syntax field number
+const fileDescriptorProtoSyntaxFieldNumber = 12
+
+// generateFile generates a _grpc.pb.go file containing gRPC service definitions.
+func generateFile(gen *protogen.Plugin, file *protogen.File) *protogen.GeneratedFile {
+	if len(file.Services) == 0 {
+		return nil
+	}
+	filename := file.GeneratedFilenamePrefix + "_grpc.pb.go"
+	g := gen.NewGeneratedFile(filename, file.GoImportPath)
+	// Attach all comments associated with the syntax field.
+	genLeadingComments(g, file.Desc.SourceLocations().ByPath(protoreflect.SourcePath{fileDescriptorProtoSyntaxFieldNumber}))
+	g.P("// Code generated by protoc-gen-go-grpc. DO NOT EDIT.")
+	g.P("// versions:")
+	g.P("// - protoc-gen-go-grpc v", version)
+	g.P("// - protoc             ", protocVersion(gen))
+	if file.Proto.GetOptions().GetDeprecated() {
+		g.P("// ", file.Desc.Path(), " is a deprecated file.")
+	} else {
+		g.P("// source: ", file.Desc.Path())
+	}
+	g.P()
+	// Attach all comments associated with the package field.
+	genLeadingComments(g, file.Desc.SourceLocations().ByPath(protoreflect.SourcePath{fileDescriptorProtoPackageFieldNumber}))
+	g.P("package ", file.GoPackageName)
+	g.P()
+	generateFileContent(gen, file, g)
+	return g
+}
+
+func protocVersion(gen *protogen.Plugin) string {
+	v := gen.Request.GetCompilerVersion()
+	if v == nil {
+		return "(unknown)"
+	}
+	var suffix string
+	if s := v.GetSuffix(); s != "" {
+		suffix = "-" + s
+	}
+	return fmt.Sprintf("v%d.%d.%d%s", v.GetMajor(), v.GetMinor(), v.GetPatch(), suffix)
+}
+
+// generateFileContent generates the gRPC service definitions, excluding the package statement.
+func generateFileContent(gen *protogen.Plugin, file *protogen.File, g *protogen.GeneratedFile) {
+	if len(file.Services) == 0 {
+		return
+	}
+
+	g.P("// This is a compile-time assertion to ensure that this generated file")
+	g.P("// is compatible with the grpc package it is being compiled against.")
+	g.P("// Requires gRPC-Go v1.64.0 or later.")
+	g.P("const _ = ", grpcPackage.Ident("SupportPackageIsVersion9"))
+	g.P()
+	for _, service := range file.Services {
+		genService(gen, file, g, service)
+	}
+}
+
+// genServiceComments copies the comments from the RPC proto definitions
+// to the corresponding generated interface file.
+func genServiceComments(g *protogen.GeneratedFile, service *protogen.Service) {
+	if service.Comments.Leading != "" {
+		// Add empty comment line to attach this service's comments to
+		// the godoc comments previously output for all services.
+		g.P("//")
+		g.P(strings.TrimSpace(service.Comments.Leading.String()))
+	}
+}
+
+func genService(gen *protogen.Plugin, file *protogen.File, g *protogen.GeneratedFile, service *protogen.Service) {
+	// Full methods constants.
+	helper.genFullMethods(g, service)
+
+	// Client interface.
+	clientName := service.GoName + "Client"
+
+	g.P("// ", clientName, " is the client API for ", service.GoName, " service.")
+	g.P("//")
+	g.P("// For semantics around ctx use and closing/ending streaming RPCs, please refer to https://pkg.go.dev/google.golang.org/grpc/?tab=doc#ClientConn.NewStream.")
+
+	// Copy comments from proto file.
+	genServiceComments(g, service)
+
+	if service.Desc.Options().(*descriptorpb.ServiceOptions).GetDeprecated() {
+		g.P("//")
+		g.P(deprecationComment)
+	}
+	g.AnnotateSymbol(clientName, protogen.Annotation{Location: service.Location})
+	g.P("type ", clientName, " interface {")
+	for _, method := range service.Methods {
+		g.AnnotateSymbol(clientName+"."+method.GoName, protogen.Annotation{Location: method.Location})
+		if method.Desc.Options().(*descriptorpb.MethodOptions).GetDeprecated() {
+			g.P(deprecationComment)
+		}
+		g.P(method.Comments.Leading,
+			clientSignature(g, method))
+	}
+	g.P("}")
+	g.P()
+
+	// Client structure.
+	helper.generateClientStruct(g, clientName)
+
+	// NewClient factory.
+	if service.Desc.Options().(*descriptorpb.ServiceOptions).GetDeprecated() {
+		g.P(deprecationComment)
+	}
+	g.P("func New", clientName, " (cc ", grpcPackage.Ident("ClientConnInterface"), ") ", clientName, " {")
+	helper.generateNewClientDefinitions(g, service, clientName)
+	g.P("}")
+	g.P()
+
+	var methodIndex, streamIndex int
+	// Client method implementations.
+	for _, method := range service.Methods {
+		if !method.Desc.IsStreamingServer() && !method.Desc.IsStreamingClient() {
+			// Unary RPC method
+			genClientMethod(gen, file, g, method, methodIndex)
+			methodIndex++
+		} else {
+			// Streaming RPC method
+			genClientMethod(gen, file, g, method, streamIndex)
+			streamIndex++
+		}
+	}
+
+	mustOrShould := "must"
+	if !*requireUnimplemented {
+		mustOrShould = "should"
+	}
+
+	// Server interface.
+	serverType := service.GoName + "Server"
+	g.P("// ", serverType, " is the server API for ", service.GoName, " service.")
+	g.P("// All implementations ", mustOrShould, " embed Unimplemented", serverType)
+	g.P("// for forward compatibility.")
+
+	// Copy comments from proto file.
+	genServiceComments(g, service)
+
+	if service.Desc.Options().(*descriptorpb.ServiceOptions).GetDeprecated() {
+		g.P("//")
+		g.P(deprecationComment)
+	}
+	g.AnnotateSymbol(serverType, protogen.Annotation{Location: service.Location})
+	g.P("type ", serverType, " interface {")
+	for _, method := range service.Methods {
+		g.AnnotateSymbol(serverType+"."+method.GoName, protogen.Annotation{Location: method.Location})
+		if method.Desc.Options().(*descriptorpb.MethodOptions).GetDeprecated() {
+			g.P(deprecationComment)
+		}
+		g.P(method.Comments.Leading,
+			serverSignature(g, method))
+	}
+	if *requireUnimplemented {
+		g.P("mustEmbedUnimplemented", serverType, "()")
+	}
+	g.P("}")
+	g.P()
+
+	// Server Unimplemented struct for forward compatibility.
+	helper.generateUnimplementedServerType(gen, file, g, service)
+
+	// Unsafe Server interface to opt-out of forward compatibility.
+	g.P("// Unsafe", serverType, " may be embedded to opt out of forward compatibility for this service.")
+	g.P("// Use of this interface is not recommended, as added methods to ", serverType, " will")
+	g.P("// result in compilation errors.")
+	g.P("type Unsafe", serverType, " interface {")
+	g.P("mustEmbedUnimplemented", serverType, "()")
+	g.P("}")
+
+	// Server registration.
+	if service.Desc.Options().(*descriptorpb.ServiceOptions).GetDeprecated() {
+		g.P(deprecationComment)
+	}
+	serviceDescVar := service.GoName + "_ServiceDesc"
+	g.P("func Register", service.GoName, "Server(s ", grpcPackage.Ident("ServiceRegistrar"), ", srv ", serverType, ") {")
+	g.P("// If the following call panics, it indicates Unimplemented", serverType, " was")
+	g.P("// embedded by pointer and is nil.  This will cause panics if an")
+	g.P("// unimplemented method is ever invoked, so we test this at initialization")
+	g.P("// time to prevent it from happening at runtime later due to I/O.")
+	g.P("if t, ok := srv.(interface { testEmbeddedByValue() }); ok {")
+	g.P("t.testEmbeddedByValue()")
+	g.P("}")
+	g.P("s.RegisterService(&", serviceDescVar, `, srv)`)
+	g.P("}")
+	g.P()
+
+	helper.generateServerFunctions(gen, file, g, service, serverType, serviceDescVar)
+}
+
+func clientSignature(g *protogen.GeneratedFile, method *protogen.Method) string {
+	s := method.GoName + "(ctx " + g.QualifiedGoIdent(contextPackage.Ident("Context"))
+	if !method.Desc.IsStreamingClient() {
+		s += ", in *" + g.QualifiedGoIdent(method.Input.GoIdent)
+	}
+	s += ", opts ..." + g.QualifiedGoIdent(grpcPackage.Ident("CallOption")) + ") ("
+	if !method.Desc.IsStreamingClient() && !method.Desc.IsStreamingServer() {
+		s += "*" + g.QualifiedGoIdent(method.Output.GoIdent)
+	} else {
+		s += clientStreamInterface(g, method)
+	}
+	s += ", error)"
+	return s
+}
+
+func clientStreamInterface(g *protogen.GeneratedFile, method *protogen.Method) string {
+	typeParam := g.QualifiedGoIdent(method.Input.GoIdent) + ", " + g.QualifiedGoIdent(method.Output.GoIdent)
+	if method.Desc.IsStreamingClient() && method.Desc.IsStreamingServer() {
+		return g.QualifiedGoIdent(grpcPackage.Ident("BidiStreamingClient")) + "[" + typeParam + "]"
+	}
+	if method.Desc.IsStreamingClient() {
+		return g.QualifiedGoIdent(grpcPackage.Ident("ClientStreamingClient")) + "[" + typeParam + "]"
+	}
+	return g.QualifiedGoIdent(grpcPackage.Ident("ServerStreamingClient")) + "[" + g.QualifiedGoIdent(method.Output.GoIdent) + "]"
+}
+
+func genClientMethod(_ *protogen.Plugin, _ *protogen.File, g *protogen.GeneratedFile, method *protogen.Method, index int) {
+	service := method.Parent
+	fmSymbol := helper.formatFullMethodSymbol(service, method)
+
+	if method.Desc.Options().(*descriptorpb.MethodOptions).GetDeprecated() {
+		g.P(deprecationComment)
+	}
+	g.P("func (c *", unexport(service.GoName), "Client) ", clientSignature(g, method), "{")
+	g.P("cOpts := append([]", grpcPackage.Ident("CallOption"), "{", grpcPackage.Ident("StaticMethod()"), "}, opts...)")
+	if !method.Desc.IsStreamingServer() && !method.Desc.IsStreamingClient() {
+		g.P("out := new(", method.Output.GoIdent, ")")
+		g.P(`err := c.cc.Invoke(ctx, `, fmSymbol, `, in, out, cOpts...)`)
+		g.P("if err != nil { return nil, err }")
+		g.P("return out, nil")
+		g.P("}")
+		g.P()
+		return
+	}
+
+	typeParam := g.QualifiedGoIdent(method.Input.GoIdent) + ", " + g.QualifiedGoIdent(method.Output.GoIdent)
+	streamImpl := g.QualifiedGoIdent(grpcPackage.Ident("GenericClientStream")) + "[" + typeParam + "]"
+	serviceDescVar := service.GoName + "_ServiceDesc"
+	g.P("stream, err := c.cc.NewStream(ctx, &", serviceDescVar, ".Streams[", index, `], `, fmSymbol, `, cOpts...)`)
+	g.P("if err != nil { return nil, err }")
+	g.P("x := &", streamImpl, "{ClientStream: stream}")
+	if !method.Desc.IsStreamingClient() {
+		g.P("if err := x.ClientStream.SendMsg(in); err != nil { return nil, err }")
+		g.P("if err := x.ClientStream.CloseSend(); err != nil { return nil, err }")
+	}
+	g.P("return x, nil")
+	g.P("}")
+	g.P()
+
+	// Auxiliary types aliases, for backwards compatibility.
+	g.P("// This type alias is provided for backwards compatibility with existing code that references the prior non-generic stream type by name.")
+	g.P("type ", service.GoName, "_", method.GoName, "Client = ", clientStreamInterface(g, method))
+	g.P()
+}
+
+func serverSignature(g *protogen.GeneratedFile, method *protogen.Method) string {
+	var reqArgs []string
+	ret := "error"
+	if !method.Desc.IsStreamingClient() && !method.Desc.IsStreamingServer() {
+		reqArgs = append(reqArgs, g.QualifiedGoIdent(contextPackage.Ident("Context")))
+		ret = "(*" + g.QualifiedGoIdent(method.Output.GoIdent) + ", error)"
+	}
+	if !method.Desc.IsStreamingClient() {
+		reqArgs = append(reqArgs, "*"+g.QualifiedGoIdent(method.Input.GoIdent))
+	}
+	if method.Desc.IsStreamingClient() || method.Desc.IsStreamingServer() {
+		reqArgs = append(reqArgs, serverStreamInterface(g, method))
+	}
+	return method.GoName + "(" + strings.Join(reqArgs, ", ") + ") " + ret
+}
+
+func genServiceDesc(file *protogen.File, g *protogen.GeneratedFile, serviceDescVar string, serverType string, service *protogen.Service, handlerNames []string) {
+	// Service descriptor.
+	g.P("// ", serviceDescVar, " is the ", grpcPackage.Ident("ServiceDesc"), " for ", service.GoName, " service.")
+	g.P("// It's only intended for direct use with ", grpcPackage.Ident("RegisterService"), ",")
+	g.P("// and not to be introspected or modified (even as a copy)")
+	g.P("var ", serviceDescVar, " = ", grpcPackage.Ident("ServiceDesc"), " {")
+	g.P("ServiceName: ", strconv.Quote(string(service.Desc.FullName())), ",")
+	g.P("HandlerType: (*", serverType, ")(nil),")
+	g.P("Methods: []", grpcPackage.Ident("MethodDesc"), "{")
+	for i, method := range service.Methods {
+		if method.Desc.IsStreamingClient() || method.Desc.IsStreamingServer() {
+			continue
+		}
+		g.P("{")
+		g.P("MethodName: ", strconv.Quote(string(method.Desc.Name())), ",")
+		g.P("Handler: ", handlerNames[i], ",")
+		g.P("},")
+	}
+	g.P("},")
+	g.P("Streams: []", grpcPackage.Ident("StreamDesc"), "{")
+	for i, method := range service.Methods {
+		if !method.Desc.IsStreamingClient() && !method.Desc.IsStreamingServer() {
+			continue
+		}
+		g.P("{")
+		g.P("StreamName: ", strconv.Quote(string(method.Desc.Name())), ",")
+		g.P("Handler: ", handlerNames[i], ",")
+		if method.Desc.IsStreamingServer() {
+			g.P("ServerStreams: true,")
+		}
+		if method.Desc.IsStreamingClient() {
+			g.P("ClientStreams: true,")
+		}
+		g.P("},")
+	}
+	g.P("},")
+	g.P("Metadata: \"", file.Desc.Path(), "\",")
+	g.P("}")
+	g.P()
+}
+
+func serverStreamInterface(g *protogen.GeneratedFile, method *protogen.Method) string {
+	typeParam := g.QualifiedGoIdent(method.Input.GoIdent) + ", " + g.QualifiedGoIdent(method.Output.GoIdent)
+	if method.Desc.IsStreamingClient() && method.Desc.IsStreamingServer() {
+		return g.QualifiedGoIdent(grpcPackage.Ident("BidiStreamingServer")) + "[" + typeParam + "]"
+	}
+	if method.Desc.IsStreamingClient() {
+		return g.QualifiedGoIdent(grpcPackage.Ident("ClientStreamingServer")) + "[" + typeParam + "]"
+	}
+
+	return g.QualifiedGoIdent(grpcPackage.Ident("ServerStreamingServer")) + "[" + g.QualifiedGoIdent(method.Output.GoIdent) + "]"
+}
+
+func genServerMethod(_ *protogen.Plugin, _ *protogen.File, g *protogen.GeneratedFile, method *protogen.Method, hnameFuncNameFormatter func(string) string) string {
+	service := method.Parent
+	hname := fmt.Sprintf("_%s_%s_Handler", service.GoName, method.GoName)
+
+	if !method.Desc.IsStreamingClient() && !method.Desc.IsStreamingServer() {
+		g.P("func ", hnameFuncNameFormatter(hname), "(srv interface{}, ctx ", contextPackage.Ident("Context"), ", dec func(interface{}) error, interceptor ", grpcPackage.Ident("UnaryServerInterceptor"), ") (interface{}, error) {")
+		g.P("in := new(", method.Input.GoIdent, ")")
+		g.P("if err := dec(in); err != nil { return nil, err }")
+		g.P("if interceptor == nil { return srv.(", service.GoName, "Server).", method.GoName, "(ctx, in) }")
+		g.P("info := &", grpcPackage.Ident("UnaryServerInfo"), "{")
+		g.P("Server: srv,")
+		fmSymbol := helper.formatFullMethodSymbol(service, method)
+		g.P("FullMethod: ", fmSymbol, ",")
+		g.P("}")
+		g.P("handler := func(ctx ", contextPackage.Ident("Context"), ", req interface{}) (interface{}, error) {")
+		g.P("return srv.(", service.GoName, "Server).", method.GoName, "(ctx, req.(*", method.Input.GoIdent, "))")
+		g.P("}")
+		g.P("return interceptor(ctx, in, info, handler)")
+		g.P("}")
+		g.P()
+		return hname
+	}
+
+	typeParam := g.QualifiedGoIdent(method.Input.GoIdent) + ", " + g.QualifiedGoIdent(method.Output.GoIdent)
+	streamImpl := g.QualifiedGoIdent(grpcPackage.Ident("GenericServerStream")) + "[" + typeParam + "]"
+
+	g.P("func ", hnameFuncNameFormatter(hname), "(srv interface{}, stream ", grpcPackage.Ident("ServerStream"), ") error {")
+	if !method.Desc.IsStreamingClient() {
+		g.P("m := new(", method.Input.GoIdent, ")")
+		g.P("if err := stream.RecvMsg(m); err != nil { return err }")
+		g.P("return srv.(", service.GoName, "Server).", method.GoName, "(m, &", streamImpl, "{ServerStream: stream})")
+	} else {
+		g.P("return srv.(", service.GoName, "Server).", method.GoName, "(&", streamImpl, "{ServerStream: stream})")
+	}
+	g.P("}")
+	g.P()
+
+	// Auxiliary types aliases, for backwards compatibility.
+	g.P("// This type alias is provided for backwards compatibility with existing code that references the prior non-generic stream type by name.")
+	g.P("type ", service.GoName, "_", method.GoName, "Server = ", serverStreamInterface(g, method))
+	g.P()
+	return hname
+}
+
+func genLeadingComments(g *protogen.GeneratedFile, loc protoreflect.SourceLocation) {
+	for _, s := range loc.LeadingDetachedComments {
+		g.P(protogen.Comments(s))
+		g.P()
+	}
+	if s := loc.LeadingComments; s != "" {
+		g.P(protogen.Comments(s))
+		g.P()
+	}
+}
+
+const deprecationComment = "// Deprecated: Do not use."
+
+func unexport(s string) string { return strings.ToLower(s[:1]) + s[1:] }