protogen

Documentation

Overview

Package protogen provides support for writing protoc plugins.

Plugins for protoc, the Protocol Buffer compiler, are programs which read a CodeGeneratorRequest message from standard input and write a CodeGeneratorResponse message to standard output. This package provides support for writing plugins which generate Go code.

Index

• type CommentSet
• type Comments
  • func (c Comments) String() string
• type Enum
• type EnumValue
• type Extension
• type Field
• type File
• type GeneratedFile
  • func (g *GeneratedFile) Annotate(symbol string, loc Location)
  • func (g *GeneratedFile) Content() ([]byte, error)
  • func (g *GeneratedFile) Import(importPath GoImportPath)
  • func (g *GeneratedFile) P(v ...interface{})
  • func (g *GeneratedFile) QualifiedGoIdent(ident GoIdent) string
  • func (g *GeneratedFile) Skip()
  • func (g *GeneratedFile) Unskip()
  • func (g *GeneratedFile) Write(p []byte) (n int, err error)
• type GoIdent
  • func (id GoIdent) String() string
• type GoImportPath
  • func (p GoImportPath) Ident(s string) GoIdent
  • func (p GoImportPath) String() string
• type GoPackageName
• type Location
• type Message
• type Method
• type Oneof
• type Options
  • func (opts Options) New(req *pluginpb.CodeGeneratorRequest) (*Plugin, error)
  • func (opts Options) Run(f func(*Plugin) error)
• type Plugin
  • func (gen *Plugin) Error(err error)
  • func (gen *Plugin) NewGeneratedFile(filename string, goImportPath GoImportPath) *GeneratedFile
  • func (gen *Plugin) Response() *pluginpb.CodeGeneratorResponse
• type Service

Types

type CommentSet

type CommentSet struct {
	LeadingDetached []Comments
	Leading         Comments
	Trailing        Comments
}

CommentSet is a set of leading and trailing comments associated with a .proto descriptor declaration.

type Comments

type Comments string

Comments is a comments string as provided by protoc.

func (Comments) String

func (c Comments) String() 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.

type 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
}

An Enum describes an enum.

type EnumValue

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
}

An EnumValue describes an enum value.

type Extension

type Extension = Field

Extension is an alias of Field for documentation.

type 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
}

A Field describes a message field.

type 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
	// contains filtered or unexported fields
}

A File describes a .proto source file.

type GeneratedFile

type GeneratedFile struct {
	// contains filtered or unexported fields
}

A GeneratedFile is a generated file.

func (*GeneratedFile) Annotate

func (g *GeneratedFile) Annotate(symbol string, loc Location)

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 (*GeneratedFile) Content

func (g *GeneratedFile) Content() ([]byte, error)

Content returns the contents of the generated file.

func (*GeneratedFile) Import

func (g *GeneratedFile) Import(importPath GoImportPath)

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 (*GeneratedFile) P

func (g *GeneratedFile) P(v ...interface{})

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 (*GeneratedFile) QualifiedGoIdent

func (g *GeneratedFile) QualifiedGoIdent(ident GoIdent) string

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 (*GeneratedFile) Skip

func (g *GeneratedFile) Skip()

Skip removes the generated file from the plugin output.

func (*GeneratedFile) Unskip

func (g *GeneratedFile) Unskip()

Unskip reverts a previous call to Skip, re-including the generated file in the plugin output.

func (*GeneratedFile) Write

func (g *GeneratedFile) Write(p []byte) (n int, err error)

Write implements io.Writer.

type GoIdent

type GoIdent struct {
	GoName       string
	GoImportPath GoImportPath
}

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.

func (GoIdent) String

func (id GoIdent) String() string

type GoImportPath

type GoImportPath string

A GoImportPath is the import path of a Go package. For example: "github.com/dactory/go-procumar/compiler/protogen"

func (GoImportPath) Ident

func (p GoImportPath) Ident(s string) GoIdent

Ident returns a GoIdent with s as the GoName and p as the GoImportPath.

func (GoImportPath) String

func (p GoImportPath) String() string

type GoPackageName

type GoPackageName string

A GoPackageName is the name of a Go package. e.g., "protobuf".

type Location

type Location struct {
	SourceFile string
	Path       protoreflect.SourcePath
}

A Location is a location in a .proto source file.

See the google.protobuf.SourceCodeInfo documentation in descriptor.proto for details.

type 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
}

A Message describes a message.

type Method

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
}

A Method describes a method in a service.

type 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
}

A Oneof describes a message oneof.

type Options

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
}

func (Options) New

func (opts Options) New(req *pluginpb.CodeGeneratorRequest) (*Plugin, error)

New returns a new Plugin.

func (Options) Run

func (opts Options) Run(f func(*Plugin) error)

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).

type Plugin

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

	// SupportedFeatures is the set of protobuf language features supported by
	// this generator plugin. See the documentation for
	// google.protobuf.CodeGeneratorResponse.supported_features for details.
	SupportedFeatures uint64
	// contains filtered or unexported fields
}

A Plugin is a protoc plugin invocation.

func (*Plugin) Error

func (gen *Plugin) Error(err error)

Error records an error in code generation. The generator will report the error back to protoc and will not produce output.

func (*Plugin) NewGeneratedFile

func (gen *Plugin) NewGeneratedFile(filename string, goImportPath GoImportPath) *GeneratedFile

NewGeneratedFile creates a new generated file with the given filename and import path.

func (*Plugin) Response

func (gen *Plugin) Response() *pluginpb.CodeGeneratorResponse

Response returns the generator output.

type 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
}

A Service describes a service.