implement the initial version of protoc-gen-pubsub-schema

Author: alpancs

example/user_add_comment.proto

@@ -0,0 +1,20 @@
+syntax = "proto3";
+
+package example;
+
+import "google/protobuf/timestamp.proto";
+
+message UserAddComment {
+  message User {
+    string first_name = 1;
+    string last_name = 2;
+    message Location {
+      double longitude = 1;
+      double latitude = 2;
+    }
+    Location location = 3;
+  }
+  User user = 1;
+  string comment = 2;
+  google.protobuf.Timestamp timestamp = 101;
+}

example/user_add_comment.pubsub.proto

@@ -0,0 +1,20 @@
+syntax = "proto3";
+
+message UserAddComment {
+  message User {
+    string first_name = 1;
+    string last_name = 2;
+    message Location {
+      double longitude = 1;
+      double latitude = 2;
+    }
+    Location location = 3;
+  }
+  User user = 1;
+  string comment = 2;
+  message Timestamp {
+    int64 seconds = 1;
+    int32 nanos = 2;
+  }
+  Timestamp timestamp = 101;
+}

go.mod

@@ -0,0 +1,5 @@
+module github.com/alpancs/protoc-gen-pubsub-schema
+
+go 1.16
+
+require google.golang.org/protobuf v1.27.1

go.sum

@@ -0,0 +1,8 @@
+github.com/golang/protobuf v1.5.0/go.mod h1:FsONVRAS9T7sI+LIUmWTfcYkHO4aIWwzhcaSAoJOfIk=
+github.com/google/go-cmp v0.5.5 h1:Khx7svrCpmxxtHBq5j2mp/xVjsi8hQMfNLvJFAlrGgU=
+github.com/google/go-cmp v0.5.5/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
+golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543 h1:E7g+9GITq07hpfrRu66IVDexMakfv52eLZ2CXBWiKr4=
+golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
+google.golang.org/protobuf v1.26.0-rc.1/go.mod h1:jlhhOSvTdKEhbULTjvd4ARK9grFBp09yW+WbY/TyQbw=
+google.golang.org/protobuf v1.27.1 h1:SnqbnDw1V7RiZcXPx5MEeqPv2s79L9i7BJUlG/+RurQ=
+google.golang.org/protobuf v1.27.1/go.mod h1:9q0QmTI4eRPtz6boOQmLYwt+qCgq0jsYwAQnmE0givc=

main.go

@@ -0,0 +1,46 @@
+package main
+
+import (
+	"io"
+	"os"
+
+	"google.golang.org/protobuf/proto"
+	"google.golang.org/protobuf/types/pluginpb"
+)
+
+func main() {
+	req, err := decodeRequest(os.Stdin)
+	if err != nil {
+		err = encodeResponse(buildResponseError(err), os.Stdout)
+		if err != nil {
+			panic(err)
+		}
+		return
+	}
+
+	err = encodeResponse(responseBuilder{req}.build(), os.Stdout)
+	if err != nil {
+		panic(err)
+	}
+}
+
+func decodeRequest(input io.Reader) (*pluginpb.CodeGeneratorRequest, error) {
+	rawInput, err := io.ReadAll(input)
+	if err != nil {
+		return nil, err
+	}
+
+	req := new(pluginpb.CodeGeneratorRequest)
+	err = proto.Unmarshal(rawInput, req)
+	return req, err
+}
+
+func encodeResponse(resp *pluginpb.CodeGeneratorResponse, output io.Writer) error {
+	rawOutput, err := proto.Marshal(resp)
+	if err != nil {
+		return err
+	}
+
+	_, err = output.Write(rawOutput)
+	return err
+}

response_builder.go

@@ -0,0 +1,119 @@
+package main
+
+import (
+	"fmt"
+	"io"
+	"regexp"
+	"strings"
+
+	"google.golang.org/protobuf/types/descriptorpb"
+	"google.golang.org/protobuf/types/pluginpb"
+)
+
+type responseBuilder struct {
+	request *pluginpb.CodeGeneratorRequest
+}
+
+func buildResponseError(err error) *pluginpb.CodeGeneratorResponse {
+	errorMessage := err.Error()
+	return &pluginpb.CodeGeneratorResponse{Error: &errorMessage}
+}
+
+func (b responseBuilder) build() *pluginpb.CodeGeneratorResponse {
+	resp := new(pluginpb.CodeGeneratorResponse)
+	for _, fileName := range b.request.GetFileToGenerate() {
+		respFile, err := b.buildFile(fileName)
+		if err != nil {
+			errorMessage := err.Error()
+			resp.Error = &errorMessage
+			break
+		}
+		resp.File = append(resp.File, respFile)
+	}
+	return resp
+}
+
+func (b responseBuilder) buildFile(reqFileName string) (*pluginpb.CodeGeneratorResponse_File, error) {
+	respFileName := regexp.MustCompile(`.proto$`).ReplaceAllString(reqFileName, ".pubsub.proto")
+	content, err := b.buildContent(b.findProtoFileByName(reqFileName))
+	return &pluginpb.CodeGeneratorResponse_File{
+		Name:    &respFileName,
+		Content: &content,
+	}, err
+}
+
+func (b responseBuilder) findProtoFileByName(desiredName string) *descriptorpb.FileDescriptorProto {
+	for _, protoFile := range b.request.GetProtoFile() {
+		if protoFile.GetName() == desiredName {
+			return protoFile
+		}
+	}
+	return nil
+}
+
+func (b responseBuilder) findMessageByName(desiredName string) *descriptorpb.DescriptorProto {
+	for _, protoFile := range b.request.GetProtoFile() {
+		packageName := strings.TrimSuffix("."+protoFile.GetPackage(), ".")
+		nestedResult := b.findNestedMessageByName(desiredName, protoFile.GetMessageType(), packageName)
+		if nestedResult != nil {
+			return nestedResult
+		}
+	}
+	return nil
+}
+
+func (b responseBuilder) findNestedMessageByName(desiredName string, messages []*descriptorpb.DescriptorProto, prefix string) *descriptorpb.DescriptorProto {
+	for _, message := range messages {
+		fullMessageName := prefix + "." + message.GetName()
+		if fullMessageName == desiredName {
+			return message
+		}
+
+		nestedResult := b.findNestedMessageByName(desiredName, message.GetNestedType(), fullMessageName)
+		if nestedResult != nil {
+			return nestedResult
+		}
+	}
+	return nil
+}
+
+func (b responseBuilder) buildContent(protoFile *descriptorpb.FileDescriptorProto) (string, error) {
+	if len(protoFile.GetMessageType()) != 1 {
+		return "", fmt.Errorf(
+			"only one top-level type may be defined in the file %s. use nested type instead (https://developers.google.com/protocol-buffers/docs/proto3#nested)",
+			protoFile.GetName(),
+		)
+	}
+
+	contentBuilder := new(strings.Builder)
+	fmt.Fprint(contentBuilder, "syntax = \"proto3\";\n\n")
+	b.buildMessage(contentBuilder, protoFile.GetMessageType()[0], 0)
+	return contentBuilder.String(), nil
+}
+
+func (b responseBuilder) buildMessage(output io.Writer, message *descriptorpb.DescriptorProto, level int) {
+	fmt.Fprintf(output, "%smessage %s {\n", buildIndent(level), message.GetName())
+	for _, field := range message.GetField() {
+		b.buildField(output, field, level+1)
+	}
+	fmt.Fprintf(output, "%s}\n", buildIndent(level))
+}
+
+func (b responseBuilder) buildField(output io.Writer, field *descriptorpb.FieldDescriptorProto, level int) {
+	fieldType := strings.ToLower(strings.Replace(field.GetType().String(), "TYPE_", "", 1))
+	if field.GetType() == descriptorpb.FieldDescriptorProto_TYPE_MESSAGE {
+		fieldTypeName := field.GetTypeName()
+		b.buildMessage(output, b.findMessageByName(fieldTypeName), level)
+		fieldType = fieldTypeName[strings.LastIndexByte(fieldTypeName, '.')+1:]
+	}
+
+	fmt.Fprint(output, buildIndent(level))
+	if field.GetLabel() == descriptorpb.FieldDescriptorProto_LABEL_REPEATED {
+		fmt.Fprint(output, "repeated ")
+	}
+	fmt.Fprintf(output, "%s %s = %d;\n", fieldType, field.GetName(), field.GetNumber())
+}
+
+func buildIndent(level int) string {
+	return strings.Repeat("  ", level)
+}