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// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Package protogen provides support for writing protoc plugins.
//
// Plugins for protoc, the Protocol Buffers Compiler, are programs which read
// a CodeGeneratorRequest protocol buffer from standard input and write a
// CodeGeneratorResponse protocol buffer to standard output. This package
// provides support for writing plugins which generate Go code.
package protogen
import (
"bufio"
"bytes"
"encoding/binary"
"fmt"
"go/ast"
"go/parser"
"go/printer"
"go/token"
"go/types"
"io/ioutil"
"log"
"os"
"path"
"path/filepath"
"sort"
"strconv"
"strings"
"google.golang.org/protobuf/encoding/prototext"
"google.golang.org/protobuf/internal/fieldnum"
"google.golang.org/protobuf/internal/strs"
"google.golang.org/protobuf/proto"
"google.golang.org/protobuf/reflect/protodesc"
"google.golang.org/protobuf/reflect/protoreflect"
"google.golang.org/protobuf/reflect/protoregistry"
"google.golang.org/protobuf/types/descriptorpb"
"google.golang.org/protobuf/types/pluginpb"
)
// Run executes a function as a protoc plugin.
//
// It reads a CodeGeneratorRequest message from os.Stdin, invokes the plugin
// function, and writes a CodeGeneratorResponse message to os.Stdout.
//
// If a failure occurs while reading or writing, Run prints an error to
// os.Stderr and calls os.Exit(1).
//
// Passing a nil options is equivalent to passing a zero-valued one.
func Run(opts *Options, f func(*Plugin) error) {
if err := run(opts, f); err != nil {
fmt.Fprintf(os.Stderr, "%s: %v\n", filepath.Base(os.Args[0]), err)
os.Exit(1)
}
}
func run(opts *Options, f func(*Plugin) error) error {
if len(os.Args) > 1 {
return fmt.Errorf("unknown argument %q (this program should be run by protoc, not directly)", os.Args[1])
}
in, err := ioutil.ReadAll(os.Stdin)
if err != nil {
return err
}
req := &pluginpb.CodeGeneratorRequest{}
if err := proto.Unmarshal(in, req); err != nil {
return err
}
gen, err := New(req, opts)
if err != nil {
return err
}
if err := f(gen); err != nil {
// Errors from the plugin function are reported by setting the
// error field in the CodeGeneratorResponse.
//
// In contrast, errors that indicate a problem in protoc
// itself (unparsable input, I/O errors, etc.) are reported
// to stderr.
gen.Error(err)
}
resp := gen.Response()
out, err := proto.Marshal(resp)
if err != nil {
return err
}
if _, err := os.Stdout.Write(out); err != nil {
return err
}
return nil
}
// A Plugin is a protoc plugin invocation.
type Plugin struct {
// Request is the CodeGeneratorRequest provided by protoc.
Request *pluginpb.CodeGeneratorRequest
// Files is the set of files to generate and everything they import.
// Files appear in topological order, so each file appears before any
// file that imports it.
Files []*File
FilesByPath map[string]*File
fileReg *protoregistry.Files
enumsByName map[protoreflect.FullName]*Enum
messagesByName map[protoreflect.FullName]*Message
annotateCode bool
pathType pathType
genFiles []*GeneratedFile
opts *Options
err error
}
// Options are optional parameters to New.
type Options struct {
// If ParamFunc is non-nil, it will be called with each unknown
// generator parameter.
//
// Plugins for protoc can accept parameters from the command line,
// passed in the --<lang>_out protoc, separated from the output
// directory with a colon; e.g.,
//
// --go_out=<param1>=<value1>,<param2>=<value2>:<output_directory>
//
// Parameters passed in this fashion as a comma-separated list of
// key=value pairs will be passed to the ParamFunc.
//
// The (flag.FlagSet).Set method matches this function signature,
// so parameters can be converted into flags as in the following:
//
// var flags flag.FlagSet
// value := flags.Bool("param", false, "")
// opts := &protogen.Options{
// ParamFunc: flags.Set,
// }
// protogen.Run(opts, func(p *protogen.Plugin) error {
// if *value { ... }
// })
ParamFunc func(name, value string) error
// ImportRewriteFunc is called with the import path of each package
// imported by a generated file. It returns the import path to use
// for this package.
ImportRewriteFunc func(GoImportPath) GoImportPath
}
// New returns a new Plugin.
//
// Passing a nil Options is equivalent to passing a zero-valued one.
func New(req *pluginpb.CodeGeneratorRequest, opts *Options) (*Plugin, error) {
if opts == nil {
opts = &Options{}
}
gen := &Plugin{
Request: req,
FilesByPath: make(map[string]*File),
fileReg: protoregistry.NewFiles(),
enumsByName: make(map[protoreflect.FullName]*Enum),
messagesByName: make(map[protoreflect.FullName]*Message),
opts: opts,
}
packageNames := make(map[string]GoPackageName) // filename -> package name
importPaths := make(map[string]GoImportPath) // filename -> import path
mfiles := make(map[string]bool) // filename set
var packageImportPath GoImportPath
for _, param := range strings.Split(req.GetParameter(), ",") {
var value string
if i := strings.Index(param, "="); i >= 0 {
value = param[i+1:]
param = param[0:i]
}
switch param {
case "":
// Ignore.
case "import_path":
packageImportPath = GoImportPath(value)
case "paths":
switch value {
case "import":
gen.pathType = pathTypeImport
case "source_relative":
gen.pathType = pathTypeSourceRelative
default:
return nil, fmt.Errorf(`unknown path type %q: want "import" or "source_relative"`, value)
}
case "annotate_code":
switch value {
case "true", "":
gen.annotateCode = true
case "false":
default:
return nil, fmt.Errorf(`bad value for parameter %q: want "true" or "false"`, param)
}
default:
if param[0] == 'M' {
importPaths[param[1:]] = GoImportPath(value)
mfiles[param[1:]] = true
continue
}
if opts.ParamFunc != nil {
if err := opts.ParamFunc(param, value); err != nil {
return nil, err
}
}
}
}
// Figure out the import path and package name for each file.
//
// The rules here are complicated and have grown organically over time.
// Interactions between different ways of specifying package information
// may be surprising.
//
// The recommended approach is to include a go_package option in every
// .proto source file specifying the full import path of the Go package
// associated with this file.
//
// option go_package = "google.golang.org/protobuf/types/known/anypb";
//
// Build systems which want to exert full control over import paths may
// specify M<filename>=<import_path> flags.
//
// Other approaches are not recommend.
generatedFileNames := make(map[string]bool)
for _, name := range gen.Request.FileToGenerate {
generatedFileNames[name] = true
}
// We need to determine the import paths before the package names,
// because the Go package name for a file is sometimes derived from
// different file in the same package.
packageNameForImportPath := make(map[GoImportPath]GoPackageName)
for _, fdesc := range gen.Request.ProtoFile {
filename := fdesc.GetName()
packageName, importPath := goPackageOption(fdesc)
switch {
case importPaths[filename] != "":
// Command line: M=foo.proto=quux/bar
//
// Explicit mapping of source file to import path.
case generatedFileNames[filename] && packageImportPath != "":
// Command line: import_path=quux/bar
//
// The import_path flag sets the import path for every file that
// we generate code for.
importPaths[filename] = packageImportPath
case importPath != "":
// Source file: option go_package = "quux/bar";
//
// The go_package option sets the import path. Most users should use this.
importPaths[filename] = importPath
default:
// Source filename.
//
// Last resort when nothing else is available.
importPaths[filename] = GoImportPath(path.Dir(filename))
}
if packageName != "" {
packageNameForImportPath[importPaths[filename]] = packageName
}
}
for _, fdesc := range gen.Request.ProtoFile {
filename := fdesc.GetName()
packageName, importPath := goPackageOption(fdesc)
defaultPackageName := packageNameForImportPath[importPaths[filename]]
switch {
case packageName != "":
// TODO: For the "M" command-line argument, this means that the
// package name can be derived from the go_package option.
// Go package information should either consistently come from the
// command-line or the .proto source file, but not both.
// See how to make this consistent.
// Source file: option go_package = "quux/bar";
packageNames[filename] = packageName
case defaultPackageName != "":
// A go_package option in another file in the same package.
//
// This is a poor choice in general, since every source file should
// contain a go_package option. Supported mainly for historical
// compatibility.
packageNames[filename] = defaultPackageName
case generatedFileNames[filename] && packageImportPath != "":
// Command line: import_path=quux/bar
packageNames[filename] = cleanPackageName(path.Base(string(packageImportPath)))
case fdesc.GetPackage() != "":
// Source file: package quux.bar;
packageNames[filename] = cleanPackageName(fdesc.GetPackage())
default:
// Source filename.
packageNames[filename] = cleanPackageName(baseName(filename))
}
goPkgOpt := string(importPaths[filename])
if path.Base(string(goPkgOpt)) != string(packageNames[filename]) {
goPkgOpt += ";" + string(packageNames[filename])
}
switch {
case packageImportPath != "":
// Command line: import_path=quux/bar
log.Printf("WARNING: Deprecated use of the 'import_path' command-line argument. In %q, please specify:\n"+
"\toption go_package = %q;\n"+
"A future release of protoc-gen-go will no longer support the 'import_path' argument.\n"+
"\n", fdesc.GetName(), goPkgOpt)
case mfiles[filename]:
// Command line: M=foo.proto=quux/bar
case packageName != "" && importPath == "":
// Source file: option go_package = "quux";
log.Printf("WARNING: Deprecated use of 'go_package' option without a full import path in %q, please specify:\n"+
"\toption go_package = %q;\n"+
"A future release of protoc-gen-go will require the import path be specified.\n"+
"\n", fdesc.GetName(), goPkgOpt)
case packageName == "" && importPath == "":
// No Go package information provided.
log.Printf("WARNING: Missing 'go_package' option in %q, please specify:\n"+
"\toption go_package = %q;\n"+
"A future release of protoc-gen-go will require this be specified.\n"+
"\n", fdesc.GetName(), goPkgOpt)
}
}
// Consistency check: Every file with the same Go import path should have
// the same Go package name.
packageFiles := make(map[GoImportPath][]string)
for filename, importPath := range importPaths {
if _, ok := packageNames[filename]; !ok {
// Skip files mentioned in a M<file>=<import_path> parameter
// but which do not appear in the CodeGeneratorRequest.
continue
}
packageFiles[importPath] = append(packageFiles[importPath], filename)
}
for importPath, filenames := range packageFiles {
for i := 1; i < len(filenames); i++ {
if a, b := packageNames[filenames[0]], packageNames[filenames[i]]; a != b {
return nil, fmt.Errorf("Go package %v has inconsistent names %v (%v) and %v (%v)",
importPath, a, filenames[0], b, filenames[i])
}
}
}
for _, fdesc := range gen.Request.ProtoFile {
filename := fdesc.GetName()
if gen.FilesByPath[filename] != nil {
return nil, fmt.Errorf("duplicate file name: %q", filename)
}
f, err := newFile(gen, fdesc, packageNames[filename], importPaths[filename])
if err != nil {
return nil, err
}
gen.Files = append(gen.Files, f)
gen.FilesByPath[filename] = f
}
for _, filename := range gen.Request.FileToGenerate {
f, ok := gen.FilesByPath[filename]
if !ok {
return nil, fmt.Errorf("no descriptor for generated file: %v", filename)
}
f.Generate = true
}
return gen, nil
}
// Error records an error in code generation. The generator will report the
// error back to protoc and will not produce output.
func (gen *Plugin) Error(err error) {
if gen.err == nil {
gen.err = err
}
}
// Response returns the generator output.
func (gen *Plugin) Response() *pluginpb.CodeGeneratorResponse {
resp := &pluginpb.CodeGeneratorResponse{}
if gen.err != nil {
resp.Error = proto.String(gen.err.Error())
return resp
}
for _, g := range gen.genFiles {
if g.skip {
continue
}
content, err := g.Content()
if err != nil {
return &pluginpb.CodeGeneratorResponse{
Error: proto.String(err.Error()),
}
}
resp.File = append(resp.File, &pluginpb.CodeGeneratorResponse_File{
Name: proto.String(g.filename),
Content: proto.String(string(content)),
})
if gen.annotateCode && strings.HasSuffix(g.filename, ".go") {
meta, err := g.metaFile(content)
if err != nil {
return &pluginpb.CodeGeneratorResponse{
Error: proto.String(err.Error()),
}
}
resp.File = append(resp.File, &pluginpb.CodeGeneratorResponse_File{
Name: proto.String(g.filename + ".meta"),
Content: proto.String(meta),
})
}
}
return resp
}
// A File describes a .proto source file.
type File struct {
Desc protoreflect.FileDescriptor
Proto *descriptorpb.FileDescriptorProto
GoDescriptorIdent GoIdent // name of Go variable for the file descriptor
GoPackageName GoPackageName // name of this file's Go package
GoImportPath GoImportPath // import path of this file's Go package
Enums []*Enum // top-level enum declarations
Messages []*Message // top-level message declarations
Extensions []*Extension // top-level extension declarations
Services []*Service // top-level service declarations
Generate bool // true if we should generate code for this file
// GeneratedFilenamePrefix is used to construct filenames for generated
// files associated with this source file.
//
// For example, the source file "dir/foo.proto" might have a filename prefix
// of "dir/foo". Appending ".pb.go" produces an output file of "dir/foo.pb.go".
GeneratedFilenamePrefix string
comments map[pathKey]CommentSet
}
func newFile(gen *Plugin, p *descriptorpb.FileDescriptorProto, packageName GoPackageName, importPath GoImportPath) (*File, error) {
desc, err := protodesc.NewFile(p, gen.fileReg)
if err != nil {
return nil, fmt.Errorf("invalid FileDescriptorProto %q: %v", p.GetName(), err)
}
if err := gen.fileReg.Register(desc); err != nil {
return nil, fmt.Errorf("cannot register descriptor %q: %v", p.GetName(), err)
}
f := &File{
Desc: desc,
Proto: p,
GoPackageName: packageName,
GoImportPath: importPath,
comments: make(map[pathKey]CommentSet),
}
// Determine the prefix for generated Go files.
prefix := p.GetName()
if ext := path.Ext(prefix); ext == ".proto" || ext == ".protodevel" {
prefix = prefix[:len(prefix)-len(ext)]
}
if gen.pathType == pathTypeImport {
// If paths=import (the default) and the file contains a go_package option
// with a full import path, the output filename is derived from the Go import
// path.
//
// Pass the paths=source_relative flag to always derive the output filename
// from the input filename instead.
if _, importPath := goPackageOption(p); importPath != "" {
prefix = path.Join(string(importPath), path.Base(prefix))
}
}
f.GoDescriptorIdent = GoIdent{
GoName: "File_" + strs.GoSanitized(p.GetName()),
GoImportPath: f.GoImportPath,
}
f.GeneratedFilenamePrefix = prefix
for _, loc := range p.GetSourceCodeInfo().GetLocation() {
// Descriptors declarations are guaranteed to have unique comment sets.
// Other locations may not be unique, but we don't use them.
var leadingDetached []Comments
for _, s := range loc.GetLeadingDetachedComments() {
leadingDetached = append(leadingDetached, Comments(s))
}
f.comments[newPathKey(loc.Path)] = CommentSet{
LeadingDetached: leadingDetached,
Leading: Comments(loc.GetLeadingComments()),
Trailing: Comments(loc.GetTrailingComments()),
}
}
for i, eds := 0, desc.Enums(); i < eds.Len(); i++ {
f.Enums = append(f.Enums, newEnum(gen, f, nil, eds.Get(i)))
}
for i, mds := 0, desc.Messages(); i < mds.Len(); i++ {
f.Messages = append(f.Messages, newMessage(gen, f, nil, mds.Get(i)))
}
for i, xds := 0, desc.Extensions(); i < xds.Len(); i++ {
f.Extensions = append(f.Extensions, newField(gen, f, nil, xds.Get(i)))
}
for i, sds := 0, desc.Services(); i < sds.Len(); i++ {
f.Services = append(f.Services, newService(gen, f, sds.Get(i)))
}
for _, message := range f.Messages {
if err := message.resolveDependencies(gen); err != nil {
return nil, err
}
}
for _, extension := range f.Extensions {
if err := extension.resolveDependencies(gen); err != nil {
return nil, err
}
}
for _, service := range f.Services {
for _, method := range service.Methods {
if err := method.resolveDependencies(gen); err != nil {
return nil, err
}
}
}
return f, nil
}
func (f *File) location(idxPath ...int32) Location {
return Location{
SourceFile: f.Desc.Path(),
Path: idxPath,
}
}
// goPackageOption interprets a file's go_package option.
// If there is no go_package, it returns ("", "").
// If there's a simple name, it returns (pkg, "").
// If the option implies an import path, it returns (pkg, impPath).
func goPackageOption(d *descriptorpb.FileDescriptorProto) (pkg GoPackageName, impPath GoImportPath) {
opt := d.GetOptions().GetGoPackage()
if opt == "" {
return "", ""
}
rawPkg, impPath := goPackageOptionRaw(opt)
pkg = cleanPackageName(rawPkg)
if string(pkg) != rawPkg && impPath != "" {
log.Printf("WARNING: Malformed 'go_package' option in %q, please specify:\n"+
"\toption go_package = %q;\n"+
"A future release of protoc-gen-go will reject this.\n"+
"\n", d.GetName(), string(impPath)+";"+string(pkg))
}
return pkg, impPath
}
func goPackageOptionRaw(opt string) (rawPkg string, impPath GoImportPath) {
// A semicolon-delimited suffix delimits the import path and package name.
if i := strings.Index(opt, ";"); i >= 0 {
return opt[i+1:], GoImportPath(opt[:i])
}
// The presence of a slash implies there's an import path.
if i := strings.LastIndex(opt, "/"); i >= 0 {
return opt[i+1:], GoImportPath(opt)
}
return opt, ""
}
// An Enum describes an enum.
type Enum struct {
Desc protoreflect.EnumDescriptor
GoIdent GoIdent // name of the generated Go type
Values []*EnumValue // enum value declarations
Location Location // location of this enum
Comments CommentSet // comments associated with this enum
}
func newEnum(gen *Plugin, f *File, parent *Message, desc protoreflect.EnumDescriptor) *Enum {
var loc Location
if parent != nil {
loc = parent.Location.appendPath(fieldnum.DescriptorProto_EnumType, int32(desc.Index()))
} else {
loc = f.location(fieldnum.FileDescriptorProto_EnumType, int32(desc.Index()))
}
enum := &Enum{
Desc: desc,
GoIdent: newGoIdent(f, desc),
Location: loc,
Comments: f.comments[newPathKey(loc.Path)],
}
gen.enumsByName[desc.FullName()] = enum
for i, vds := 0, enum.Desc.Values(); i < vds.Len(); i++ {
enum.Values = append(enum.Values, newEnumValue(gen, f, parent, enum, vds.Get(i)))
}
return enum
}
// An EnumValue describes an enum value.
type EnumValue struct {
Desc protoreflect.EnumValueDescriptor
GoIdent GoIdent // name of the generated Go declaration
Parent *Enum // enum in which this value is declared
Location Location // location of this enum value
Comments CommentSet // comments associated with this enum value
}
func newEnumValue(gen *Plugin, f *File, message *Message, enum *Enum, desc protoreflect.EnumValueDescriptor) *EnumValue {
// A top-level enum value's name is: EnumName_ValueName
// An enum value contained in a message is: MessageName_ValueName
//
// For historical reasons, enum value names are not camel-cased.
parentIdent := enum.GoIdent
if message != nil {
parentIdent = message.GoIdent
}
name := parentIdent.GoName + "_" + string(desc.Name())
loc := enum.Location.appendPath(fieldnum.EnumDescriptorProto_Value, int32(desc.Index()))
return &EnumValue{
Desc: desc,
GoIdent: f.GoImportPath.Ident(name),
Parent: enum,
Location: loc,
Comments: f.comments[newPathKey(loc.Path)],
}
}
// A Message describes a message.
type Message struct {
Desc protoreflect.MessageDescriptor
GoIdent GoIdent // name of the generated Go type
Fields []*Field // message field declarations
Oneofs []*Oneof // message oneof declarations
Enums []*Enum // nested enum declarations
Messages []*Message // nested message declarations
Extensions []*Extension // nested extension declarations
Location Location // location of this message
Comments CommentSet // comments associated with this message
}
func newMessage(gen *Plugin, f *File, parent *Message, desc protoreflect.MessageDescriptor) *Message {
var loc Location
if parent != nil {
loc = parent.Location.appendPath(fieldnum.DescriptorProto_NestedType, int32(desc.Index()))
} else {
loc = f.location(fieldnum.FileDescriptorProto_MessageType, int32(desc.Index()))
}
message := &Message{
Desc: desc,
GoIdent: newGoIdent(f, desc),
Location: loc,
Comments: f.comments[newPathKey(loc.Path)],
}
gen.messagesByName[desc.FullName()] = message
for i, eds := 0, desc.Enums(); i < eds.Len(); i++ {
message.Enums = append(message.Enums, newEnum(gen, f, message, eds.Get(i)))
}
for i, mds := 0, desc.Messages(); i < mds.Len(); i++ {
message.Messages = append(message.Messages, newMessage(gen, f, message, mds.Get(i)))
}
for i, fds := 0, desc.Fields(); i < fds.Len(); i++ {
message.Fields = append(message.Fields, newField(gen, f, message, fds.Get(i)))
}
for i, ods := 0, desc.Oneofs(); i < ods.Len(); i++ {
message.Oneofs = append(message.Oneofs, newOneof(gen, f, message, ods.Get(i)))
}
for i, xds := 0, desc.Extensions(); i < xds.Len(); i++ {
message.Extensions = append(message.Extensions, newField(gen, f, message, xds.Get(i)))
}
// Resolve local references between fields and oneofs.
for _, field := range message.Fields {
if od := field.Desc.ContainingOneof(); od != nil {
oneof := message.Oneofs[od.Index()]
field.Oneof = oneof
oneof.Fields = append(oneof.Fields, field)
}
}
// Field name conflict resolution.
//
// We assume well-known method names that may be attached to a generated
// message type, as well as a 'Get*' method for each field. For each
// field in turn, we add _s to its name until there are no conflicts.
//
// Any change to the following set of method names is a potential
// incompatible API change because it may change generated field names.
//
// TODO: If we ever support a 'go_name' option to set the Go name of a
// field, we should consider dropping this entirely. The conflict
// resolution algorithm is subtle and surprising (changing the order
// in which fields appear in the .proto source file can change the
// names of fields in generated code), and does not adapt well to
// adding new per-field methods such as setters.
usedNames := map[string]bool{
"Reset": true,
"String": true,
"ProtoMessage": true,
"Marshal": true,
"Unmarshal": true,
"ExtensionRangeArray": true,
"ExtensionMap": true,
"Descriptor": true,
}
makeNameUnique := func(name string, hasGetter bool) string {
for usedNames[name] || (hasGetter && usedNames["Get"+name]) {
name += "_"
}
usedNames[name] = true
usedNames["Get"+name] = hasGetter
return name
}
for _, field := range message.Fields {
field.GoName = makeNameUnique(field.GoName, true)
field.GoIdent.GoName = message.GoIdent.GoName + "_" + field.GoName
if field.Oneof != nil && field.Oneof.Fields[0] == field {
// Make the name for a oneof unique as well. For historical reasons,
// this assumes that a getter method is not generated for oneofs.
// This is incorrect, but fixing it breaks existing code.
field.Oneof.GoName = makeNameUnique(field.Oneof.GoName, false)
field.Oneof.GoIdent.GoName = message.GoIdent.GoName + "_" + field.Oneof.GoName
}
}
// Oneof field name conflict resolution.
//
// This conflict resolution is incomplete as it does not consider collisions
// with other oneof field types, but fixing it breaks existing code.
for _, field := range message.Fields {
if field.Oneof != nil {
Loop:
for {
for _, nestedMessage := range message.Messages {
if nestedMessage.GoIdent == field.GoIdent {
field.GoIdent.GoName += "_"
continue Loop
}
}
for _, nestedEnum := range message.Enums {
if nestedEnum.GoIdent == field.GoIdent {
field.GoIdent.GoName += "_"
continue Loop
}
}
break Loop
}
}
}
return message
}
func (message *Message) resolveDependencies(gen *Plugin) error {
for _, field := range message.Fields {
if err := field.resolveDependencies(gen); err != nil {
return err
}
}
for _, message := range message.Messages {
if err := message.resolveDependencies(gen); err != nil {
return err
}
}
for _, extension := range message.Extensions {
if err := extension.resolveDependencies(gen); err != nil {
return err
}
}
return nil
}
// A Field describes a message field.
type Field struct {
Desc protoreflect.FieldDescriptor
// GoName is the base name of this field's Go field and methods.
// For code generated by protoc-gen-go, this means a field named
// '{{GoName}}' and a getter method named 'Get{{GoName}}'.
GoName string // e.g., "FieldName"
// GoIdent is the base name of a top-level declaration for this field.
// For code generated by protoc-gen-go, this means a wrapper type named
// '{{GoIdent}}' for members fields of a oneof, and a variable named
// 'E_{{GoIdent}}' for extension fields.
GoIdent GoIdent // e.g., "MessageName_FieldName"
Parent *Message // message in which this field is declared; nil if top-level extension
Oneof *Oneof // containing oneof; nil if not part of a oneof
Extendee *Message // extended message for extension fields; nil otherwise
Enum *Enum // type for enum fields; nil otherwise
Message *Message // type for message or group fields; nil otherwise
Location Location // location of this field
Comments CommentSet // comments associated with this field
}
func newField(gen *Plugin, f *File, message *Message, desc protoreflect.FieldDescriptor) *Field {
var loc Location
switch {
case desc.IsExtension() && message == nil:
loc = f.location(fieldnum.FileDescriptorProto_Extension, int32(desc.Index()))
case desc.IsExtension() && message != nil:
loc = message.Location.appendPath(fieldnum.DescriptorProto_Extension, int32(desc.Index()))
default:
loc = message.Location.appendPath(fieldnum.DescriptorProto_Field, int32(desc.Index()))
}
camelCased := strs.GoCamelCase(string(desc.Name()))
var parentPrefix string
if message != nil {
parentPrefix = message.GoIdent.GoName + "_"
}
field := &Field{
Desc: desc,
GoName: camelCased,
GoIdent: GoIdent{
GoImportPath: f.GoImportPath,
GoName: parentPrefix + camelCased,
},
Parent: message,
Location: loc,
Comments: f.comments[newPathKey(loc.Path)],
}
return field
}
func (field *Field) resolveDependencies(gen *Plugin) error {
desc := field.Desc
switch desc.Kind() {
case protoreflect.EnumKind:
name := field.Desc.Enum().FullName()
enum, ok := gen.enumsByName[name]
if !ok {
return fmt.Errorf("field %v: no descriptor for enum %v", desc.FullName(), name)
}
field.Enum = enum
case protoreflect.MessageKind, protoreflect.GroupKind:
name := desc.Message().FullName()
message, ok := gen.messagesByName[name]
if !ok {
return fmt.Errorf("field %v: no descriptor for type %v", desc.FullName(), name)
}
field.Message = message
}
if desc.IsExtension() {
name := desc.ContainingMessage().FullName()
message, ok := gen.messagesByName[name]
if !ok {
return fmt.Errorf("field %v: no descriptor for type %v", desc.FullName(), name)
}
field.Extendee = message
}
return nil
}
// A Oneof describes a message oneof.
type Oneof struct {
Desc protoreflect.OneofDescriptor
// GoName is the base name of this oneof's Go field and methods.
// For code generated by protoc-gen-go, this means a field named
// '{{GoName}}' and a getter method named 'Get{{GoName}}'.
GoName string // e.g., "OneofName"
// GoIdent is the base name of a top-level declaration for this oneof.
GoIdent GoIdent // e.g., "MessageName_OneofName"
Parent *Message // message in which this oneof is declared
Fields []*Field // fields that are part of this oneof
Location Location // location of this oneof
Comments CommentSet // comments associated with this oneof
}
func newOneof(gen *Plugin, f *File, message *Message, desc protoreflect.OneofDescriptor) *Oneof {
loc := message.Location.appendPath(fieldnum.DescriptorProto_OneofDecl, int32(desc.Index()))
camelCased := strs.GoCamelCase(string(desc.Name()))
parentPrefix := message.GoIdent.GoName + "_"
return &Oneof{
Desc: desc,
Parent: message,
GoName: camelCased,
GoIdent: GoIdent{
GoImportPath: f.GoImportPath,
GoName: parentPrefix + camelCased,
},
Location: loc,
Comments: f.comments[newPathKey(loc.Path)],
}
}
// Extension is an alias of Field for documentation.
type Extension = Field
// A Service describes a service.
type Service struct {
Desc protoreflect.ServiceDescriptor
GoName string
Methods []*Method // service method declarations
Location Location // location of this service
Comments CommentSet // comments associated with this service
}
func newService(gen *Plugin, f *File, desc protoreflect.ServiceDescriptor) *Service {
loc := f.location(fieldnum.FileDescriptorProto_Service, int32(desc.Index()))
service := &Service{
Desc: desc,
GoName: strs.GoCamelCase(string(desc.Name())),
Location: loc,
Comments: f.comments[newPathKey(loc.Path)],
}
for i, mds := 0, desc.Methods(); i < mds.Len(); i++ {
service.Methods = append(service.Methods, newMethod(gen, f, service, mds.Get(i)))
}
return service
}
// A Method describes a method in a service.
type Method struct {
Desc protoreflect.MethodDescriptor
GoName string
Parent *Service // service in which this method is declared
Input *Message
Output *Message
Location Location // location of this method
Comments CommentSet // comments associated with this method
}
func newMethod(gen *Plugin, f *File, service *Service, desc protoreflect.MethodDescriptor) *Method {
loc := service.Location.appendPath(fieldnum.ServiceDescriptorProto_Method, int32(desc.Index()))
method := &Method{
Desc: desc,
GoName: strs.GoCamelCase(string(desc.Name())),
Parent: service,
Location: loc,
Comments: f.comments[newPathKey(loc.Path)],
}
return method
}
func (method *Method) resolveDependencies(gen *Plugin) error {
desc := method.Desc
inName := desc.Input().FullName()
in, ok := gen.messagesByName[inName]
if !ok {
return fmt.Errorf("method %v: no descriptor for type %v", desc.FullName(), inName)
}
method.Input = in
outName := desc.Output().FullName()
out, ok := gen.messagesByName[outName]
if !ok {
return fmt.Errorf("method %v: no descriptor for type %v", desc.FullName(), outName)
}
method.Output = out
return nil
}
// A GeneratedFile is a generated file.
type GeneratedFile struct {
gen *Plugin
skip bool
filename string
goImportPath GoImportPath
buf bytes.Buffer
packageNames map[GoImportPath]GoPackageName
usedPackageNames map[GoPackageName]bool
manualImports map[GoImportPath]bool
annotations map[string][]Location
}
// NewGeneratedFile creates a new generated file with the given filename
// and import path.
func (gen *Plugin) NewGeneratedFile(filename string, goImportPath GoImportPath) *GeneratedFile {
g := &GeneratedFile{
gen: gen,
filename: filename,
goImportPath: goImportPath,
packageNames: make(map[GoImportPath]GoPackageName),
usedPackageNames: make(map[GoPackageName]bool),
manualImports: make(map[GoImportPath]bool),
annotations: make(map[string][]Location),
}
// All predeclared identifiers in Go are already used.
for _, s := range types.Universe.Names() {
g.usedPackageNames[GoPackageName(s)] = true
}
gen.genFiles = append(gen.genFiles, g)
return g
}
// P prints a line to the generated output. It converts each parameter to a
// string following the same rules as fmt.Print. It never inserts spaces
// between parameters.
func (g *GeneratedFile) P(v ...interface{}) {
for _, x := range v {
switch x := x.(type) {
case GoIdent:
fmt.Fprint(&g.buf, g.QualifiedGoIdent(x))
default:
fmt.Fprint(&g.buf, x)
}
}
fmt.Fprintln(&g.buf)
}
// QualifiedGoIdent returns the string to use for a Go identifier.
//
// If the identifier is from a different Go package than the generated file,
// the returned name will be qualified (package.name) and an import statement
// for the identifier's package will be included in the file.
func (g *GeneratedFile) QualifiedGoIdent(ident GoIdent) string {
if ident.GoImportPath == g.goImportPath {
return ident.GoName
}
if packageName, ok := g.packageNames[ident.GoImportPath]; ok {
return string(packageName) + "." + ident.GoName
}
packageName := cleanPackageName(baseName(string(ident.GoImportPath)))
for i, orig := 1, packageName; g.usedPackageNames[packageName]; i++ {
packageName = orig + GoPackageName(strconv.Itoa(i))
}
g.packageNames[ident.GoImportPath] = packageName
g.usedPackageNames[packageName] = true
return string(packageName) + "." + ident.GoName
}
// Import ensures a package is imported by the generated file.
//
// Packages referenced by QualifiedGoIdent are automatically imported.
// Explicitly importing a package with Import is generally only necessary
// when the import will be blank (import _ "package").
func (g *GeneratedFile) Import(importPath GoImportPath) {
g.manualImports[importPath] = true
}
// Write implements io.Writer.
func (g *GeneratedFile) Write(p []byte) (n int, err error) {
return g.buf.Write(p)
}
// Skip removes the generated file from the plugin output.
func (g *GeneratedFile) Skip() {
g.skip = true
}
// Annotate associates a symbol in a generated Go file with a location in a
// source .proto file.
//
// The symbol may refer to a type, constant, variable, function, method, or
// struct field. The "T.sel" syntax is used to identify the method or field
// 'sel' on type 'T'.
func (g *GeneratedFile) Annotate(symbol string, loc Location) {
g.annotations[symbol] = append(g.annotations[symbol], loc)
}
// Content returns the contents of the generated file.
func (g *GeneratedFile) Content() ([]byte, error) {
if !strings.HasSuffix(g.filename, ".go") {
return g.buf.Bytes(), nil
}
// Reformat generated code.
original := g.buf.Bytes()
fset := token.NewFileSet()
file, err := parser.ParseFile(fset, "", original, parser.ParseComments)
if err != nil {
// Print out the bad code with line numbers.
// This should never happen in practice, but it can while changing generated code
// so consider this a debugging aid.
var src bytes.Buffer
s := bufio.NewScanner(bytes.NewReader(original))
for line := 1; s.Scan(); line++ {
fmt.Fprintf(&src, "%5d\t%s\n", line, s.Bytes())
}
return nil, fmt.Errorf("%v: unparsable Go source: %v\n%v", g.filename, err, src.String())
}
// Collect a sorted list of all imports.
var importPaths [][2]string
rewriteImport := func(importPath string) string {
if f := g.gen.opts.ImportRewriteFunc; f != nil {
return string(f(GoImportPath(importPath)))
}
return importPath
}
for importPath := range g.packageNames {
pkgName := string(g.packageNames[GoImportPath(importPath)])
pkgPath := rewriteImport(string(importPath))
importPaths = append(importPaths, [2]string{pkgName, pkgPath})
}
for importPath := range g.manualImports {
if _, ok := g.packageNames[importPath]; !ok {
pkgPath := rewriteImport(string(importPath))
importPaths = append(importPaths, [2]string{"_", pkgPath})
}
}
sort.Slice(importPaths, func(i, j int) bool {
return importPaths[i][1] < importPaths[j][1]
})
// Modify the AST to include a new import block.
if len(importPaths) > 0 {
// Insert block after package statement or
// possible comment attached to the end of the package statement.
pos := file.Package
tokFile := fset.File(file.Package)
pkgLine := tokFile.Line(file.Package)
for _, c := range file.Comments {
if tokFile.Line(c.Pos()) > pkgLine {
break
}
pos = c.End()
}
// Construct the import block.
impDecl := &ast.GenDecl{
Tok: token.IMPORT,
TokPos: pos,
Lparen: pos,
Rparen: pos,
}
for _, importPath := range importPaths {
impDecl.Specs = append(impDecl.Specs, &ast.ImportSpec{
Name: &ast.Ident{
Name: importPath[0],
NamePos: pos,
},
Path: &ast.BasicLit{
Kind: token.STRING,
Value: strconv.Quote(importPath[1]),
ValuePos: pos,
},
EndPos: pos,
})
}
file.Decls = append([]ast.Decl{impDecl}, file.Decls...)
}
var out bytes.Buffer
if err = (&printer.Config{Mode: printer.TabIndent | printer.UseSpaces, Tabwidth: 8}).Fprint(&out, fset, file); err != nil {
return nil, fmt.Errorf("%v: can not reformat Go source: %v", g.filename, err)
}
return out.Bytes(), nil
}
// metaFile returns the contents of the file's metadata file, which is a
// text formatted string of the google.protobuf.GeneratedCodeInfo.
func (g *GeneratedFile) metaFile(content []byte) (string, error) {
fset := token.NewFileSet()
astFile, err := parser.ParseFile(fset, "", content, 0)
if err != nil {
return "", err
}
info := &descriptorpb.GeneratedCodeInfo{}
seenAnnotations := make(map[string]bool)
annotate := func(s string, ident *ast.Ident) {
seenAnnotations[s] = true
for _, loc := range g.annotations[s] {
info.Annotation = append(info.Annotation, &descriptorpb.GeneratedCodeInfo_Annotation{
SourceFile: proto.String(loc.SourceFile),
Path: loc.Path,
Begin: proto.Int32(int32(fset.Position(ident.Pos()).Offset)),
End: proto.Int32(int32(fset.Position(ident.End()).Offset)),
})
}
}
for _, decl := range astFile.Decls {
switch decl := decl.(type) {
case *ast.GenDecl:
for _, spec := range decl.Specs {
switch spec := spec.(type) {
case *ast.TypeSpec:
annotate(spec.Name.Name, spec.Name)
switch st := spec.Type.(type) {
case *ast.StructType:
for _, field := range st.Fields.List {
for _, name := range field.Names {
annotate(spec.Name.Name+"."+name.Name, name)
}
}
case *ast.InterfaceType:
for _, field := range st.Methods.List {
for _, name := range field.Names {
annotate(spec.Name.Name+"."+name.Name, name)
}
}
}
case *ast.ValueSpec:
for _, name := range spec.Names {
annotate(name.Name, name)
}
}
}
case *ast.FuncDecl:
if decl.Recv == nil {
annotate(decl.Name.Name, decl.Name)
} else {
recv := decl.Recv.List[0].Type
if s, ok := recv.(*ast.StarExpr); ok {
recv = s.X
}
if id, ok := recv.(*ast.Ident); ok {
annotate(id.Name+"."+decl.Name.Name, decl.Name)
}
}
}
}
for a := range g.annotations {
if !seenAnnotations[a] {
return "", fmt.Errorf("%v: no symbol matching annotation %q", g.filename, a)
}
}
b, err := prototext.Marshal(info)
if err != nil {
return "", err
}
return string(b), nil
}
// A GoIdent is a Go identifier, consisting of a name and import path.
// The name is a single identifier and may not be a dot-qualified selector.
type GoIdent struct {
GoName string
GoImportPath GoImportPath
}
func (id GoIdent) String() string { return fmt.Sprintf("%q.%v", id.GoImportPath, id.GoName) }
// newGoIdent returns the Go identifier for a descriptor.
func newGoIdent(f *File, d protoreflect.Descriptor) GoIdent {
name := strings.TrimPrefix(string(d.FullName()), string(f.Desc.Package())+".")
return GoIdent{
GoName: strs.GoCamelCase(name),
GoImportPath: f.GoImportPath,
}
}
// A GoImportPath is the import path of a Go package.
// For example: "google.golang.org/protobuf/compiler/protogen"
type GoImportPath string
func (p GoImportPath) String() string { return strconv.Quote(string(p)) }
// Ident returns a GoIdent with s as the GoName and p as the GoImportPath.
func (p GoImportPath) Ident(s string) GoIdent {
return GoIdent{GoName: s, GoImportPath: p}
}
// A GoPackageName is the name of a Go package. e.g., "protobuf".
type GoPackageName string
// cleanPackageName converts a string to a valid Go package name.
func cleanPackageName(name string) GoPackageName {
return GoPackageName(strs.GoSanitized(name))
}
// baseName returns the last path element of the name, with the last dotted suffix removed.
func baseName(name string) string {
// First, find the last element
if i := strings.LastIndex(name, "/"); i >= 0 {
name = name[i+1:]
}
// Now drop the suffix
if i := strings.LastIndex(name, "."); i >= 0 {
name = name[:i]
}
return name
}
type pathType int
const (
pathTypeImport pathType = iota
pathTypeSourceRelative
)
// A Location is a location in a .proto source file.
//
// See the google.protobuf.SourceCodeInfo documentation in descriptor.proto
// for details.
type Location struct {
SourceFile string
Path protoreflect.SourcePath
}
// appendPath add elements to a Location's path, returning a new Location.
func (loc Location) appendPath(a ...int32) Location {
var n protoreflect.SourcePath
n = append(n, loc.Path...)
n = append(n, a...)
return Location{
SourceFile: loc.SourceFile,
Path: n,
}
}
// A pathKey is a representation of a location path suitable for use as a map key.
type pathKey struct {
s string
}
// newPathKey converts a location path to a pathKey.
func newPathKey(idxPath []int32) pathKey {
buf := make([]byte, 4*len(idxPath))
for i, x := range idxPath {
binary.LittleEndian.PutUint32(buf[i*4:], uint32(x))
}
return pathKey{string(buf)}
}
// CommentSet is a set of leading and trailing comments associated
// with a .proto descriptor declaration.
type CommentSet struct {
LeadingDetached []Comments
Leading Comments
Trailing Comments
}
// Comments is a comments string as provided by protoc.
type Comments string
// String formats the comments by inserting // to the start of each line,
// ensuring that there is a trailing newline.
// An empty comment is formatted as an empty string.
func (c Comments) String() string {
if c == "" {
return ""
}
var b []byte
for _, line := range strings.Split(strings.TrimSuffix(string(c), "\n"), "\n") {
b = append(b, "//"...)
b = append(b, line...)
b = append(b, "\n"...)
}
return string(b)
}