custom-options.pb.go

// Code generated by protoc-gen-go. DO NOT EDIT.
// source: custom-options.proto

/*
Package main is a generated protocol buffer package.

It is generated from these files:
	custom-options.proto

It has these top-level messages:
	MessageListOptions
*/
package main

import proto "github.com/golang/protobuf/proto"
import fmt "fmt"
import math "math"
import google_protobuf "github.com/golang/protobuf/protoc-gen-go/descriptor"

// Reference imports to suppress errors if they are not otherwise used.
var _ = proto.Marshal
var _ = fmt.Errorf
var _ = math.Inf

// This is a compile-time assertion to ensure that this generated file
// is compatible with the proto package it is being compiled against.
// A compilation error at this line likely means your copy of the
// proto package needs to be updated.
const _ = proto.ProtoPackageIsVersion2 // please upgrade the proto package

type MessageListOptions struct {
	Target bool `protobuf:"varint,10,opt,name=target" json:"target,omitempty"`
}

func (m *MessageListOptions) Reset()                    { *m = MessageListOptions{} }
func (m *MessageListOptions) String() string            { return proto.CompactTextString(m) }
func (*MessageListOptions) ProtoMessage()               {}
func (*MessageListOptions) Descriptor() ([]byte, []int) { return fileDescriptor0, []int{0} }

func (m *MessageListOptions) GetTarget() bool {
	if m != nil {
		return m.Target
	}
	return false
}

var E_MessageList = &proto.ExtensionDesc{
	ExtendedType:  (*google_protobuf.MessageOptions)(nil),
	ExtensionType: (*MessageListOptions)(nil),
	Field:         50000,
	Name:          "example.message_list",
	Tag:           "bytes,50000,opt,name=message_list,json=messageList",
	Filename:      "custom-options.proto",
}

func init() {
	proto.RegisterType((*MessageListOptions)(nil), "example.MessageListOptions")
	proto.RegisterExtension(E_MessageList)
}

func init() { proto.RegisterFile("custom-options.proto", fileDescriptor0) }

var fileDescriptor0 = []byte{
	// 179 bytes of a gzipped FileDescriptorProto
	0x1f, 0x8b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02, 0xff, 0xe2, 0x12, 0x49, 0x2e, 0x2d, 0x2e,
	0xc9, 0xcf, 0xd5, 0xcd, 0x2f, 0x28, 0xc9, 0xcc, 0xcf, 0x2b, 0xd6, 0x2b, 0x28, 0xca, 0x2f, 0xc9,
	0x17, 0x62, 0x4f, 0xad, 0x48, 0xcc, 0x2d, 0xc8, 0x49, 0x95, 0x52, 0x48, 0xcf, 0xcf, 0x4f, 0xcf,
	0x49, 0xd5, 0x07, 0x0b, 0x27, 0x95, 0xa6, 0xe9, 0xa7, 0xa4, 0x16, 0x27, 0x17, 0x65, 0x16, 0x94,
	0xe4, 0x17, 0x41, 0x94, 0x2a, 0xe9, 0x70, 0x09, 0xf9, 0xa6, 0x16, 0x17, 0x27, 0xa6, 0xa7, 0xfa,
	0x64, 0x16, 0x97, 0xf8, 0x43, 0x8c, 0x11, 0x12, 0xe3, 0x62, 0x2b, 0x49, 0x2c, 0x4a, 0x4f, 0x2d,
	0x91, 0xe0, 0x52, 0x60, 0xd4, 0xe0, 0x08, 0x82, 0xf2, 0xac, 0x12, 0xb9, 0x78, 0x72, 0x21, 0xaa,
	0xe3, 0x73, 0x32, 0x8b, 0x4b, 0x84, 0xe4, 0xf5, 0x20, 0x16, 0xe8, 0xc1, 0x2c, 0xd0, 0x83, 0x1a,
	0x06, 0x35, 0x48, 0xe2, 0x42, 0x1b, 0xb3, 0x02, 0xa3, 0x06, 0xb7, 0x91, 0xb4, 0x1e, 0xd4, 0x49,
	0x7a, 0x98, 0xb6, 0x05, 0x71, 0xe7, 0x22, 0xc4, 0x9c, 0xd8, 0xa2, 0x58, 0x72, 0x13, 0x33, 0xf3,
	0x92, 0xd8, 0xc0, 0x46, 0x1a, 0x03, 0x02, 0x00, 0x00, 0xff, 0xff, 0xb5, 0xa5, 0xdc, 0x88, 0xe2,
	0x00, 0x00, 0x00,
}

custom-options.proto

syntax = "proto3";
package example;
option go_package = "main";

import "google/protobuf/descriptor.proto";

message MessageListOptions {
	bool target = 10;
}

extend google.protobuf.MessageOptions {
	MessageListOptions message_list = 50000;
}

main.go

package main

import (
	"bytes"
	"io"
	"io/ioutil"
	"log"
	"os"

	"github.com/golang/protobuf/proto"
	descriptor "github.com/golang/protobuf/protoc-gen-go/descriptor"
	plugin "github.com/golang/protobuf/protoc-gen-go/plugin"
)

func parseReq(r io.Reader) (*plugin.CodeGeneratorRequest, error) {
	buf, err := ioutil.ReadAll(r)
	if err != nil {
		return nil, err
	}

	var req plugin.CodeGeneratorRequest
	if err = proto.Unmarshal(buf, &req); err != nil {
		return nil, err
	}
	return &req, nil
}

func listNames(file *descriptor.FileDescriptorProto) []string {
	var list []string
	for _, m := range file.MessageType {
		if !isTarget(m) {
			continue
		}
		list = append(list, m.GetName())
	}
	return list
}

func isTarget(m *descriptor.DescriptorProto) bool {
	var opts = m.GetOptions()
	if opts == nil {
		return false
	}

	ext, err := proto.GetExtension(opts, E_MessageList)
	if err == proto.ErrMissingExtension {
		return false
	}
	if err != nil {
		panic("unexpected error")
	}

	mopts := ext.(*MessageListOptions)
	return mopts.GetTarget()
}

func processReq(req *plugin.CodeGeneratorRequest) *plugin.CodeGeneratorResponse {
	files := make(map[string]*descriptor.FileDescriptorProto)
	for _, f := range req.ProtoFile {
		files[f.GetName()] = f
	}

	var buf bytes.Buffer
	for _, fname := range req.FileToGenerate {
		f := files[fname]
		for _, name := range listNames(f) {
			io.WriteString(&buf, name)
			io.WriteString(&buf, "\n")
		}
	}

	return &plugin.CodeGeneratorResponse{
		File: []*plugin.CodeGeneratorResponse_File{
			{
				Name:    proto.String("messages.txt"),
				Content: proto.String(buf.String()),
			},
		},
	}
}

func emitResp(resp *plugin.CodeGeneratorResponse) error {
	buf, err := proto.Marshal(resp)
	if err != nil {
		return err
	}
	_, err = os.Stdout.Write(buf)
	return err
}

func run() error {
	req, err := parseReq(os.Stdin)
	if err != nil {
		return err
	}

	resp := processReq(req)

	return emitResp(resp)
}

func main() {
	if err := run(); err != nil {
		log.Fatalln(err)
	}
}