Code refactoring for bpa operator

[icn.git] / cmd / bpa-operator / vendor / github.com / golang / protobuf / protoc-gen-go / generator / generator.go

// Go support for Protocol Buffers - Google's data interchange format
//
// Copyright 2010 The Go Authors.  All rights reserved.
// https://github.com/golang/protobuf
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
//     * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
//     * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
//     * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

/*
        The code generator for the plugin for the Google protocol buffer compiler.
        It generates Go code from the protocol buffer description files read by the
        main routine.
*/
package generator

import (
        "bufio"
        "bytes"
        "compress/gzip"
        "crypto/sha256"
        "encoding/hex"
        "fmt"
        "go/ast"
        "go/build"
        "go/parser"
        "go/printer"
        "go/token"
        "log"
        "os"
        "path"
        "sort"
        "strconv"
        "strings"
        "unicode"
        "unicode/utf8"

        "github.com/golang/protobuf/proto"
        "github.com/golang/protobuf/protoc-gen-go/generator/internal/remap"

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

// generatedCodeVersion indicates a version of the generated code.
// It is incremented whenever an incompatibility between the generated code and
// proto package is introduced; the generated code references
// a constant, proto.ProtoPackageIsVersionN (where N is generatedCodeVersion).
const generatedCodeVersion = 3

// A Plugin provides functionality to add to the output during Go code generation,
// such as to produce RPC stubs.
type Plugin interface {
        // Name identifies the plugin.
        Name() string
        // Init is called once after data structures are built but before
        // code generation begins.
        Init(g *Generator)
        // Generate produces the code generated by the plugin for this file,
        // except for the imports, by calling the generator's methods P, In, and Out.
        Generate(file *FileDescriptor)
        // GenerateImports produces the import declarations for this file.
        // It is called after Generate.
        GenerateImports(file *FileDescriptor)
}

var plugins []Plugin

// RegisterPlugin installs a (second-order) plugin to be run when the Go output is generated.
// It is typically called during initialization.
func RegisterPlugin(p Plugin) {
        plugins = append(plugins, p)
}

// A GoImportPath is the import path of a Go package. e.g., "google.golang.org/genproto/protobuf".
type GoImportPath string

func (p GoImportPath) String() string { return strconv.Quote(string(p)) }

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

// Each type we import as a protocol buffer (other than FileDescriptorProto) needs
// a pointer to the FileDescriptorProto that represents it.  These types achieve that
// wrapping by placing each Proto inside a struct with the pointer to its File. The
// structs have the same names as their contents, with "Proto" removed.
// FileDescriptor is used to store the things that it points to.

// The file and package name method are common to messages and enums.
type common struct {
        file *FileDescriptor // File this object comes from.
}

// GoImportPath is the import path of the Go package containing the type.
func (c *common) GoImportPath() GoImportPath {
        return c.file.importPath
}

func (c *common) File() *FileDescriptor { return c.file }

func fileIsProto3(file *descriptor.FileDescriptorProto) bool {
        return file.GetSyntax() == "proto3"
}

func (c *common) proto3() bool { return fileIsProto3(c.file.FileDescriptorProto) }

// Descriptor represents a protocol buffer message.
type Descriptor struct {
        common
        *descriptor.DescriptorProto
        parent   *Descriptor            // The containing message, if any.
        nested   []*Descriptor          // Inner messages, if any.
        enums    []*EnumDescriptor      // Inner enums, if any.
        ext      []*ExtensionDescriptor // Extensions, if any.
        typename []string               // Cached typename vector.
        index    int                    // The index into the container, whether the file or another message.
        path     string                 // The SourceCodeInfo path as comma-separated integers.
        group    bool
}

// TypeName returns the elements of the dotted type name.
// The package name is not part of this name.
func (d *Descriptor) TypeName() []string {
        if d.typename != nil {
                return d.typename
        }
        n := 0
        for parent := d; parent != nil; parent = parent.parent {
                n++
        }
        s := make([]string, n)
        for parent := d; parent != nil; parent = parent.parent {
                n--
                s[n] = parent.GetName()
        }
        d.typename = s
        return s
}

// EnumDescriptor describes an enum. If it's at top level, its parent will be nil.
// Otherwise it will be the descriptor of the message in which it is defined.
type EnumDescriptor struct {
        common
        *descriptor.EnumDescriptorProto
        parent   *Descriptor // The containing message, if any.
        typename []string    // Cached typename vector.
        index    int         // The index into the container, whether the file or a message.
        path     string      // The SourceCodeInfo path as comma-separated integers.
}

// TypeName returns the elements of the dotted type name.
// The package name is not part of this name.
func (e *EnumDescriptor) TypeName() (s []string) {
        if e.typename != nil {
                return e.typename
        }
        name := e.GetName()
        if e.parent == nil {
                s = make([]string, 1)
        } else {
                pname := e.parent.TypeName()
                s = make([]string, len(pname)+1)
                copy(s, pname)
        }
        s[len(s)-1] = name
        e.typename = s
        return s
}

// Everything but the last element of the full type name, CamelCased.
// The values of type Foo.Bar are call Foo_value1... not Foo_Bar_value1... .
func (e *EnumDescriptor) prefix() string {
        if e.parent == nil {
                // If the enum is not part of a message, the prefix is just the type name.
                return CamelCase(*e.Name) + "_"
        }
        typeName := e.TypeName()
        return CamelCaseSlice(typeName[0:len(typeName)-1]) + "_"
}

// The integer value of the named constant in this enumerated type.
func (e *EnumDescriptor) integerValueAsString(name string) string {
        for _, c := range e.Value {
                if c.GetName() == name {
                        return fmt.Sprint(c.GetNumber())
                }
        }
        log.Fatal("cannot find value for enum constant")
        return ""
}

// ExtensionDescriptor describes an extension. If it's at top level, its parent will be nil.
// Otherwise it will be the descriptor of the message in which it is defined.
type ExtensionDescriptor struct {
        common
        *descriptor.FieldDescriptorProto
        parent *Descriptor // The containing message, if any.
}

// TypeName returns the elements of the dotted type name.
// The package name is not part of this name.
func (e *ExtensionDescriptor) TypeName() (s []string) {
        name := e.GetName()
        if e.parent == nil {
                // top-level extension
                s = make([]string, 1)
        } else {
                pname := e.parent.TypeName()
                s = make([]string, len(pname)+1)
                copy(s, pname)
        }
        s[len(s)-1] = name
        return s
}

// DescName returns the variable name used for the generated descriptor.
func (e *ExtensionDescriptor) DescName() string {
        // The full type name.
        typeName := e.TypeName()
        // Each scope of the extension is individually CamelCased, and all are joined with "_" with an "E_" prefix.
        for i, s := range typeName {
                typeName[i] = CamelCase(s)
        }
        return "E_" + strings.Join(typeName, "_")
}

// ImportedDescriptor describes a type that has been publicly imported from another file.
type ImportedDescriptor struct {
        common
        o Object
}

func (id *ImportedDescriptor) TypeName() []string { return id.o.TypeName() }

// FileDescriptor describes an protocol buffer descriptor file (.proto).
// It includes slices of all the messages and enums defined within it.
// Those slices are constructed by WrapTypes.
type FileDescriptor struct {
        *descriptor.FileDescriptorProto
        desc []*Descriptor          // All the messages defined in this file.
        enum []*EnumDescriptor      // All the enums defined in this file.
        ext  []*ExtensionDescriptor // All the top-level extensions defined in this file.
        imp  []*ImportedDescriptor  // All types defined in files publicly imported by this file.

        // Comments, stored as a map of path (comma-separated integers) to the comment.
        comments map[string]*descriptor.SourceCodeInfo_Location

        // The full list of symbols that are exported,
        // as a map from the exported object to its symbols.
        // This is used for supporting public imports.
        exported map[Object][]symbol

        importPath  GoImportPath  // Import path of this file's package.
        packageName GoPackageName // Name of this file's Go package.

        proto3 bool // whether to generate proto3 code for this file
}

// VarName is the variable name we'll use in the generated code to refer
// to the compressed bytes of this descriptor. It is not exported, so
// it is only valid inside the generated package.
func (d *FileDescriptor) VarName() string {
        h := sha256.Sum256([]byte(d.GetName()))
        return fmt.Sprintf("fileDescriptor_%s", hex.EncodeToString(h[:8]))
}

// goPackageOption interprets the file's go_package option.
// If there is no go_package, it returns ("", "", false).
// If there's a simple name, it returns ("", pkg, true).
// If the option implies an import path, it returns (impPath, pkg, true).
func (d *FileDescriptor) goPackageOption() (impPath GoImportPath, pkg GoPackageName, ok bool) {
        opt := d.GetOptions().GetGoPackage()
        if opt == "" {
                return "", "", false
        }
        // A semicolon-delimited suffix delimits the import path and package name.
        sc := strings.Index(opt, ";")
        if sc >= 0 {
                return GoImportPath(opt[:sc]), cleanPackageName(opt[sc+1:]), true
        }
        // The presence of a slash implies there's an import path.
        slash := strings.LastIndex(opt, "/")
        if slash >= 0 {
                return GoImportPath(opt), cleanPackageName(opt[slash+1:]), true
        }
        return "", cleanPackageName(opt), true
}

// goFileName returns the output name for the generated Go file.
func (d *FileDescriptor) goFileName(pathType pathType) string {
        name := *d.Name
        if ext := path.Ext(name); ext == ".proto" || ext == ".protodevel" {
                name = name[:len(name)-len(ext)]
        }
        name += ".pb.go"

        if pathType == pathTypeSourceRelative {
                return name
        }

        // Does the file have a "go_package" option?
        // If it does, it may override the filename.
        if impPath, _, ok := d.goPackageOption(); ok && impPath != "" {
                // Replace the existing dirname with the declared import path.
                _, name = path.Split(name)
                name = path.Join(string(impPath), name)
                return name
        }

        return name
}

func (d *FileDescriptor) addExport(obj Object, sym symbol) {
        d.exported[obj] = append(d.exported[obj], sym)
}

// symbol is an interface representing an exported Go symbol.
type symbol interface {
        // GenerateAlias should generate an appropriate alias
        // for the symbol from the named package.
        GenerateAlias(g *Generator, filename string, pkg GoPackageName)
}

type messageSymbol struct {
        sym                         string
        hasExtensions, isMessageSet bool
        oneofTypes                  []string
}

type getterSymbol struct {
        name     string
        typ      string
        typeName string // canonical name in proto world; empty for proto.Message and similar
        genType  bool   // whether typ contains a generated type (message/group/enum)
}

func (ms *messageSymbol) GenerateAlias(g *Generator, filename string, pkg GoPackageName) {
        g.P("// ", ms.sym, " from public import ", filename)
        g.P("type ", ms.sym, " = ", pkg, ".", ms.sym)
        for _, name := range ms.oneofTypes {
                g.P("type ", name, " = ", pkg, ".", name)
        }
}

type enumSymbol struct {
        name   string
        proto3 bool // Whether this came from a proto3 file.
}

func (es enumSymbol) GenerateAlias(g *Generator, filename string, pkg GoPackageName) {
        s := es.name
        g.P("// ", s, " from public import ", filename)
        g.P("type ", s, " = ", pkg, ".", s)
        g.P("var ", s, "_name = ", pkg, ".", s, "_name")
        g.P("var ", s, "_value = ", pkg, ".", s, "_value")
}

type constOrVarSymbol struct {
        sym  string
        typ  string // either "const" or "var"
        cast string // if non-empty, a type cast is required (used for enums)
}

func (cs constOrVarSymbol) GenerateAlias(g *Generator, filename string, pkg GoPackageName) {
        v := string(pkg) + "." + cs.sym
        if cs.cast != "" {
                v = cs.cast + "(" + v + ")"
        }
        g.P(cs.typ, " ", cs.sym, " = ", v)
}

// Object is an interface abstracting the abilities shared by enums, messages, extensions and imported objects.
type Object interface {
        GoImportPath() GoImportPath
        TypeName() []string
        File() *FileDescriptor
}

// Generator is the type whose methods generate the output, stored in the associated response structure.
type Generator struct {
        *bytes.Buffer

        Request  *plugin.CodeGeneratorRequest  // The input.
        Response *plugin.CodeGeneratorResponse // The output.

        Param             map[string]string // Command-line parameters.
        PackageImportPath string            // Go import path of the package we're generating code for
        ImportPrefix      string            // String to prefix to imported package file names.
        ImportMap         map[string]string // Mapping from .proto file name to import path

        Pkg map[string]string // The names under which we import support packages

        outputImportPath GoImportPath                   // Package we're generating code for.
        allFiles         []*FileDescriptor              // All files in the tree
        allFilesByName   map[string]*FileDescriptor     // All files by filename.
        genFiles         []*FileDescriptor              // Those files we will generate output for.
        file             *FileDescriptor                // The file we are compiling now.
        packageNames     map[GoImportPath]GoPackageName // Imported package names in the current file.
        usedPackages     map[GoImportPath]bool          // Packages used in current file.
        usedPackageNames map[GoPackageName]bool         // Package names used in the current file.
        addedImports     map[GoImportPath]bool          // Additional imports to emit.
        typeNameToObject map[string]Object              // Key is a fully-qualified name in input syntax.
        init             []string                       // Lines to emit in the init function.
        indent           string
        pathType         pathType // How to generate output filenames.
        writeOutput      bool
        annotateCode     bool                                       // whether to store annotations
        annotations      []*descriptor.GeneratedCodeInfo_Annotation // annotations to store
}

type pathType int

const (
        pathTypeImport pathType = iota
        pathTypeSourceRelative
)

// New creates a new generator and allocates the request and response protobufs.
func New() *Generator {
        g := new(Generator)
        g.Buffer = new(bytes.Buffer)
        g.Request = new(plugin.CodeGeneratorRequest)
        g.Response = new(plugin.CodeGeneratorResponse)
        return g
}

// Error reports a problem, including an error, and exits the program.
func (g *Generator) Error(err error, msgs ...string) {
        s := strings.Join(msgs, " ") + ":" + err.Error()
        log.Print("protoc-gen-go: error:", s)
        os.Exit(1)
}

// Fail reports a problem and exits the program.
func (g *Generator) Fail(msgs ...string) {
        s := strings.Join(msgs, " ")
        log.Print("protoc-gen-go: error:", s)
        os.Exit(1)
}

// CommandLineParameters breaks the comma-separated list of key=value pairs
// in the parameter (a member of the request protobuf) into a key/value map.
// It then sets file name mappings defined by those entries.
func (g *Generator) CommandLineParameters(parameter string) {
        g.Param = make(map[string]string)
        for _, p := range strings.Split(parameter, ",") {
                if i := strings.Index(p, "="); i < 0 {
                        g.Param[p] = ""
                } else {
                        g.Param[p[0:i]] = p[i+1:]
                }
        }

        g.ImportMap = make(map[string]string)
        pluginList := "none" // Default list of plugin names to enable (empty means all).
        for k, v := range g.Param {
                switch k {
                case "import_prefix":
                        g.ImportPrefix = v
                case "import_path":
                        g.PackageImportPath = v
                case "paths":
                        switch v {
                        case "import":
                                g.pathType = pathTypeImport
                        case "source_relative":
                                g.pathType = pathTypeSourceRelative
                        default:
                                g.Fail(fmt.Sprintf(`Unknown path type %q: want "import" or "source_relative".`, v))
                        }
                case "plugins":
                        pluginList = v
                case "annotate_code":
                        if v == "true" {
                                g.annotateCode = true
                        }
                default:
                        if len(k) > 0 && k[0] == 'M' {
                                g.ImportMap[k[1:]] = v
                        }
                }
        }
        if pluginList != "" {
                // Amend the set of plugins.
                enabled := make(map[string]bool)
                for _, name := range strings.Split(pluginList, "+") {
                        enabled[name] = true
                }
                var nplugins []Plugin
                for _, p := range plugins {
                        if enabled[p.Name()] {
                                nplugins = append(nplugins, p)
                        }
                }
                plugins = nplugins
        }
}

// DefaultPackageName returns the package name printed for the object.
// If its file is in a different package, it returns the package name we're using for this file, plus ".".
// Otherwise it returns the empty string.
func (g *Generator) DefaultPackageName(obj Object) string {
        importPath := obj.GoImportPath()
        if importPath == g.outputImportPath {
                return ""
        }
        return string(g.GoPackageName(importPath)) + "."
}

// GoPackageName returns the name used for a package.
func (g *Generator) GoPackageName(importPath GoImportPath) GoPackageName {
        if name, ok := g.packageNames[importPath]; ok {
                return name
        }
        name := cleanPackageName(baseName(string(importPath)))
        for i, orig := 1, name; g.usedPackageNames[name] || isGoPredeclaredIdentifier[string(name)]; i++ {
                name = orig + GoPackageName(strconv.Itoa(i))
        }
        g.packageNames[importPath] = name
        g.usedPackageNames[name] = true
        return name
}

// AddImport adds a package to the generated file's import section.
// It returns the name used for the package.
func (g *Generator) AddImport(importPath GoImportPath) GoPackageName {
        g.addedImports[importPath] = true
        return g.GoPackageName(importPath)
}

var globalPackageNames = map[GoPackageName]bool{
        "fmt":   true,
        "math":  true,
        "proto": true,
}

// Create and remember a guaranteed unique package name. Pkg is the candidate name.
// The FileDescriptor parameter is unused.
func RegisterUniquePackageName(pkg string, f *FileDescriptor) string {
        name := cleanPackageName(pkg)
        for i, orig := 1, name; globalPackageNames[name]; i++ {
                name = orig + GoPackageName(strconv.Itoa(i))
        }
        globalPackageNames[name] = true
        return string(name)
}

var isGoKeyword = map[string]bool{
        "break":       true,
        "case":        true,
        "chan":        true,
        "const":       true,
        "continue":    true,
        "default":     true,
        "else":        true,
        "defer":       true,
        "fallthrough": true,
        "for":         true,
        "func":        true,
        "go":          true,
        "goto":        true,
        "if":          true,
        "import":      true,
        "interface":   true,
        "map":         true,
        "package":     true,
        "range":       true,
        "return":      true,
        "select":      true,
        "struct":      true,
        "switch":      true,
        "type":        true,
        "var":         true,
}

var isGoPredeclaredIdentifier = map[string]bool{
        "append":     true,
        "bool":       true,
        "byte":       true,
        "cap":        true,
        "close":      true,
        "complex":    true,
        "complex128": true,
        "complex64":  true,
        "copy":       true,
        "delete":     true,
        "error":      true,
        "false":      true,
        "float32":    true,
        "float64":    true,
        "imag":       true,
        "int":        true,
        "int16":      true,
        "int32":      true,
        "int64":      true,
        "int8":       true,
        "iota":       true,
        "len":        true,
        "make":       true,
        "new":        true,
        "nil":        true,
        "panic":      true,
        "print":      true,
        "println":    true,
        "real":       true,
        "recover":    true,
        "rune":       true,
        "string":     true,
        "true":       true,
        "uint":       true,
        "uint16":     true,
        "uint32":     true,
        "uint64":     true,
        "uint8":      true,
        "uintptr":    true,
}

func cleanPackageName(name string) GoPackageName {
        name = strings.Map(badToUnderscore, name)
        // Identifier must not be keyword or predeclared identifier: insert _.
        if isGoKeyword[name] {
                name = "_" + name
        }
        // Identifier must not begin with digit: insert _.
        if r, _ := utf8.DecodeRuneInString(name); unicode.IsDigit(r) {
                name = "_" + name
        }
        return GoPackageName(name)
}

// defaultGoPackage returns the package name to use,
// derived from the import path of the package we're building code for.
func (g *Generator) defaultGoPackage() GoPackageName {
        p := g.PackageImportPath
        if i := strings.LastIndex(p, "/"); i >= 0 {
                p = p[i+1:]
        }
        return cleanPackageName(p)
}

// SetPackageNames sets the package name for this run.
// The package name must agree across all files being generated.
// It also defines unique package names for all imported files.
func (g *Generator) SetPackageNames() {
        g.outputImportPath = g.genFiles[0].importPath

        defaultPackageNames := make(map[GoImportPath]GoPackageName)
        for _, f := range g.genFiles {
                if _, p, ok := f.goPackageOption(); ok {
                        defaultPackageNames[f.importPath] = p
                }
        }
        for _, f := range g.genFiles {
                if _, p, ok := f.goPackageOption(); ok {
                        // Source file: option go_package = "quux/bar";
                        f.packageName = p
                } else if p, ok := defaultPackageNames[f.importPath]; ok {
                        // 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.
                        f.packageName = p
                } else if p := g.defaultGoPackage(); p != "" {
                        // Command-line: import_path=quux/bar.
                        //
                        // The import_path flag sets a package name for files which don't
                        // contain a go_package option.
                        f.packageName = p
                } else if p := f.GetPackage(); p != "" {
                        // Source file: package quux.bar;
                        f.packageName = cleanPackageName(p)
                } else {
                        // Source filename.
                        f.packageName = cleanPackageName(baseName(f.GetName()))
                }
        }

        // Check that all files have a consistent package name and import path.
        for _, f := range g.genFiles[1:] {
                if a, b := g.genFiles[0].importPath, f.importPath; a != b {
                        g.Fail(fmt.Sprintf("inconsistent package import paths: %v, %v", a, b))
                }
                if a, b := g.genFiles[0].packageName, f.packageName; a != b {
                        g.Fail(fmt.Sprintf("inconsistent package names: %v, %v", a, b))
                }
        }

        // Names of support packages. These never vary (if there are conflicts,
        // we rename the conflicting package), so this could be removed someday.
        g.Pkg = map[string]string{
                "fmt":   "fmt",
                "math":  "math",
                "proto": "proto",
        }
}

// WrapTypes walks the incoming data, wrapping DescriptorProtos, EnumDescriptorProtos
// and FileDescriptorProtos into file-referenced objects within the Generator.
// It also creates the list of files to generate and so should be called before GenerateAllFiles.
func (g *Generator) WrapTypes() {
        g.allFiles = make([]*FileDescriptor, 0, len(g.Request.ProtoFile))
        g.allFilesByName = make(map[string]*FileDescriptor, len(g.allFiles))
        genFileNames := make(map[string]bool)
        for _, n := range g.Request.FileToGenerate {
                genFileNames[n] = true
        }
        for _, f := range g.Request.ProtoFile {
                fd := &FileDescriptor{
                        FileDescriptorProto: f,
                        exported:            make(map[Object][]symbol),
                        proto3:              fileIsProto3(f),
                }
                // The import path may be set in a number of ways.
                if substitution, ok := g.ImportMap[f.GetName()]; ok {
                        // Command-line: M=foo.proto=quux/bar.
                        //
                        // Explicit mapping of source file to import path.
                        fd.importPath = GoImportPath(substitution)
                } else if genFileNames[f.GetName()] && g.PackageImportPath != "" {
                        // Command-line: import_path=quux/bar.
                        //
                        // The import_path flag sets the import path for every file that
                        // we generate code for.
                        fd.importPath = GoImportPath(g.PackageImportPath)
                } else if p, _, _ := fd.goPackageOption(); p != "" {
                        // Source file: option go_package = "quux/bar";
                        //
                        // The go_package option sets the import path. Most users should use this.
                        fd.importPath = p
                } else {
                        // Source filename.
                        //
                        // Last resort when nothing else is available.
                        fd.importPath = GoImportPath(path.Dir(f.GetName()))
                }
                // We must wrap the descriptors before we wrap the enums
                fd.desc = wrapDescriptors(fd)
                g.buildNestedDescriptors(fd.desc)
                fd.enum = wrapEnumDescriptors(fd, fd.desc)
                g.buildNestedEnums(fd.desc, fd.enum)
                fd.ext = wrapExtensions(fd)
                extractComments(fd)
                g.allFiles = append(g.allFiles, fd)
                g.allFilesByName[f.GetName()] = fd
        }
        for _, fd := range g.allFiles {
                fd.imp = wrapImported(fd, g)
        }

        g.genFiles = make([]*FileDescriptor, 0, len(g.Request.FileToGenerate))
        for _, fileName := range g.Request.FileToGenerate {
                fd := g.allFilesByName[fileName]
                if fd == nil {
                        g.Fail("could not find file named", fileName)
                }
                g.genFiles = append(g.genFiles, fd)
        }
}

// Scan the descriptors in this file.  For each one, build the slice of nested descriptors
func (g *Generator) buildNestedDescriptors(descs []*Descriptor) {
        for _, desc := range descs {
                if len(desc.NestedType) != 0 {
                        for _, nest := range descs {
                                if nest.parent == desc {
                                        desc.nested = append(desc.nested, nest)
                                }
                        }
                        if len(desc.nested) != len(desc.NestedType) {
                                g.Fail("internal error: nesting failure for", desc.GetName())
                        }
                }
        }
}

func (g *Generator) buildNestedEnums(descs []*Descriptor, enums []*EnumDescriptor) {
        for _, desc := range descs {
                if len(desc.EnumType) != 0 {
                        for _, enum := range enums {
                                if enum.parent == desc {
                                        desc.enums = append(desc.enums, enum)
                                }
                        }
                        if len(desc.enums) != len(desc.EnumType) {
                                g.Fail("internal error: enum nesting failure for", desc.GetName())
                        }
                }
        }
}

// Construct the Descriptor
func newDescriptor(desc *descriptor.DescriptorProto, parent *Descriptor, file *FileDescriptor, index int) *Descriptor {
        d := &Descriptor{
                common:          common{file},
                DescriptorProto: desc,
                parent:          parent,
                index:           index,
        }
        if parent == nil {
                d.path = fmt.Sprintf("%d,%d", messagePath, index)
        } else {
                d.path = fmt.Sprintf("%s,%d,%d", parent.path, messageMessagePath, index)
        }

        // The only way to distinguish a group from a message is whether
        // the containing message has a TYPE_GROUP field that matches.
        if parent != nil {
                parts := d.TypeName()
                if file.Package != nil {
                        parts = append([]string{*file.Package}, parts...)
                }
                exp := "." + strings.Join(parts, ".")
                for _, field := range parent.Field {
                        if field.GetType() == descriptor.FieldDescriptorProto_TYPE_GROUP && field.GetTypeName() == exp {
                                d.group = true
                                break
                        }
                }
        }

        for _, field := range desc.Extension {
                d.ext = append(d.ext, &ExtensionDescriptor{common{file}, field, d})
        }

        return d
}

// Return a slice of all the Descriptors defined within this file
func wrapDescriptors(file *FileDescriptor) []*Descriptor {
        sl := make([]*Descriptor, 0, len(file.MessageType)+10)
        for i, desc := range file.MessageType {
                sl = wrapThisDescriptor(sl, desc, nil, file, i)
        }
        return sl
}

// Wrap this Descriptor, recursively
func wrapThisDescriptor(sl []*Descriptor, desc *descriptor.DescriptorProto, parent *Descriptor, file *FileDescriptor, index int) []*Descriptor {
        sl = append(sl, newDescriptor(desc, parent, file, index))
        me := sl[len(sl)-1]
        for i, nested := range desc.NestedType {
                sl = wrapThisDescriptor(sl, nested, me, file, i)
        }
        return sl
}

// Construct the EnumDescriptor
func newEnumDescriptor(desc *descriptor.EnumDescriptorProto, parent *Descriptor, file *FileDescriptor, index int) *EnumDescriptor {
        ed := &EnumDescriptor{
                common:              common{file},
                EnumDescriptorProto: desc,
                parent:              parent,
                index:               index,
        }
        if parent == nil {
                ed.path = fmt.Sprintf("%d,%d", enumPath, index)
        } else {
                ed.path = fmt.Sprintf("%s,%d,%d", parent.path, messageEnumPath, index)
        }
        return ed
}

// Return a slice of all the EnumDescriptors defined within this file
func wrapEnumDescriptors(file *FileDescriptor, descs []*Descriptor) []*EnumDescriptor {
        sl := make([]*EnumDescriptor, 0, len(file.EnumType)+10)
        // Top-level enums.
        for i, enum := range file.EnumType {
                sl = append(sl, newEnumDescriptor(enum, nil, file, i))
        }
        // Enums within messages. Enums within embedded messages appear in the outer-most message.
        for _, nested := range descs {
                for i, enum := range nested.EnumType {
                        sl = append(sl, newEnumDescriptor(enum, nested, file, i))
                }
        }
        return sl
}

// Return a slice of all the top-level ExtensionDescriptors defined within this file.
func wrapExtensions(file *FileDescriptor) []*ExtensionDescriptor {
        var sl []*ExtensionDescriptor
        for _, field := range file.Extension {
                sl = append(sl, &ExtensionDescriptor{common{file}, field, nil})
        }
        return sl
}

// Return a slice of all the types that are publicly imported into this file.
func wrapImported(file *FileDescriptor, g *Generator) (sl []*ImportedDescriptor) {
        for _, index := range file.PublicDependency {
                df := g.fileByName(file.Dependency[index])
                for _, d := range df.desc {
                        if d.GetOptions().GetMapEntry() {
                                continue
                        }
                        sl = append(sl, &ImportedDescriptor{common{file}, d})
                }
                for _, e := range df.enum {
                        sl = append(sl, &ImportedDescriptor{common{file}, e})
                }
                for _, ext := range df.ext {
                        sl = append(sl, &ImportedDescriptor{common{file}, ext})
                }
        }
        return
}

func extractComments(file *FileDescriptor) {
        file.comments = make(map[string]*descriptor.SourceCodeInfo_Location)
        for _, loc := range file.GetSourceCodeInfo().GetLocation() {
                if loc.LeadingComments == nil {
                        continue
                }
                var p []string
                for _, n := range loc.Path {
                        p = append(p, strconv.Itoa(int(n)))
                }
                file.comments[strings.Join(p, ",")] = loc
        }
}

// BuildTypeNameMap builds the map from fully qualified type names to objects.
// The key names for the map come from the input data, which puts a period at the beginning.
// It should be called after SetPackageNames and before GenerateAllFiles.
func (g *Generator) BuildTypeNameMap() {
        g.typeNameToObject = make(map[string]Object)
        for _, f := range g.allFiles {
                // The names in this loop are defined by the proto world, not us, so the
                // package name may be empty.  If so, the dotted package name of X will
                // be ".X"; otherwise it will be ".pkg.X".
                dottedPkg := "." + f.GetPackage()
                if dottedPkg != "." {
                        dottedPkg += "."
                }
                for _, enum := range f.enum {
                        name := dottedPkg + dottedSlice(enum.TypeName())
                        g.typeNameToObject[name] = enum
                }
                for _, desc := range f.desc {
                        name := dottedPkg + dottedSlice(desc.TypeName())
                        g.typeNameToObject[name] = desc
                }
        }
}

// ObjectNamed, given a fully-qualified input type name as it appears in the input data,
// returns the descriptor for the message or enum with that name.
func (g *Generator) ObjectNamed(typeName string) Object {
        o, ok := g.typeNameToObject[typeName]
        if !ok {
                g.Fail("can't find object with type", typeName)
        }
        return o
}

// AnnotatedAtoms is a list of atoms (as consumed by P) that records the file name and proto AST path from which they originated.
type AnnotatedAtoms struct {
        source string
        path   string
        atoms  []interface{}
}

// Annotate records the file name and proto AST path of a list of atoms
// so that a later call to P can emit a link from each atom to its origin.
func Annotate(file *FileDescriptor, path string, atoms ...interface{}) *AnnotatedAtoms {
        return &AnnotatedAtoms{source: *file.Name, path: path, atoms: atoms}
}

// printAtom prints the (atomic, non-annotation) argument to the generated output.
func (g *Generator) printAtom(v interface{}) {
        switch v := v.(type) {
        case string:
                g.WriteString(v)
        case *string:
                g.WriteString(*v)
        case bool:
                fmt.Fprint(g, v)
        case *bool:
                fmt.Fprint(g, *v)
        case int:
                fmt.Fprint(g, v)
        case *int32:
                fmt.Fprint(g, *v)
        case *int64:
                fmt.Fprint(g, *v)
        case float64:
                fmt.Fprint(g, v)
        case *float64:
                fmt.Fprint(g, *v)
        case GoPackageName:
                g.WriteString(string(v))
        case GoImportPath:
                g.WriteString(strconv.Quote(string(v)))
        default:
                g.Fail(fmt.Sprintf("unknown type in printer: %T", v))
        }
}

// P prints the arguments to the generated output.  It handles strings and int32s, plus
// handling indirections because they may be *string, etc.  Any inputs of type AnnotatedAtoms may emit
// annotations in a .meta file in addition to outputting the atoms themselves (if g.annotateCode
// is true).
func (g *Generator) P(str ...interface{}) {
        if !g.writeOutput {
                return
        }
        g.WriteString(g.indent)
        for _, v := range str {
                switch v := v.(type) {
                case *AnnotatedAtoms:
                        begin := int32(g.Len())
                        for _, v := range v.atoms {
                                g.printAtom(v)
                        }
                        if g.annotateCode {
                                end := int32(g.Len())
                                var path []int32
                                for _, token := range strings.Split(v.path, ",") {
                                        val, err := strconv.ParseInt(token, 10, 32)
                                        if err != nil {
                                                g.Fail("could not parse proto AST path: ", err.Error())
                                        }
                                        path = append(path, int32(val))
                                }
                                g.annotations = append(g.annotations, &descriptor.GeneratedCodeInfo_Annotation{
                                        Path:       path,
                                        SourceFile: &v.source,
                                        Begin:      &begin,
                                        End:        &end,
                                })
                        }
                default:
                        g.printAtom(v)
                }
        }
        g.WriteByte('\n')
}

// addInitf stores the given statement to be printed inside the file's init function.
// The statement is given as a format specifier and arguments.
func (g *Generator) addInitf(stmt string, a ...interface{}) {
        g.init = append(g.init, fmt.Sprintf(stmt, a...))
}

// In Indents the output one tab stop.
func (g *Generator) In() { g.indent += "\t" }

// Out unindents the output one tab stop.
func (g *Generator) Out() {
        if len(g.indent) > 0 {
                g.indent = g.indent[1:]
        }
}

// GenerateAllFiles generates the output for all the files we're outputting.
func (g *Generator) GenerateAllFiles() {
        // Initialize the plugins
        for _, p := range plugins {
                p.Init(g)
        }
        // Generate the output. The generator runs for every file, even the files
        // that we don't generate output for, so that we can collate the full list
        // of exported symbols to support public imports.
        genFileMap := make(map[*FileDescriptor]bool, len(g.genFiles))
        for _, file := range g.genFiles {
                genFileMap[file] = true
        }
        for _, file := range g.allFiles {
                g.Reset()
                g.annotations = nil
                g.writeOutput = genFileMap[file]
                g.generate(file)
                if !g.writeOutput {
                        continue
                }
                fname := file.goFileName(g.pathType)
                g.Response.File = append(g.Response.File, &plugin.CodeGeneratorResponse_File{
                        Name:    proto.String(fname),
                        Content: proto.String(g.String()),
                })
                if g.annotateCode {
                        // Store the generated code annotations in text, as the protoc plugin protocol requires that
                        // strings contain valid UTF-8.
                        g.Response.File = append(g.Response.File, &plugin.CodeGeneratorResponse_File{
                                Name:    proto.String(file.goFileName(g.pathType) + ".meta"),
                                Content: proto.String(proto.CompactTextString(&descriptor.GeneratedCodeInfo{Annotation: g.annotations})),
                        })
                }
        }
}

// Run all the plugins associated with the file.
func (g *Generator) runPlugins(file *FileDescriptor) {
        for _, p := range plugins {
                p.Generate(file)
        }
}

// Fill the response protocol buffer with the generated output for all the files we're
// supposed to generate.
func (g *Generator) generate(file *FileDescriptor) {
        g.file = file
        g.usedPackages = make(map[GoImportPath]bool)
        g.packageNames = make(map[GoImportPath]GoPackageName)
        g.usedPackageNames = make(map[GoPackageName]bool)
        g.addedImports = make(map[GoImportPath]bool)
        for name := range globalPackageNames {
                g.usedPackageNames[name] = true
        }

        g.P("// This is a compile-time assertion to ensure that this generated file")
        g.P("// is compatible with the proto package it is being compiled against.")
        g.P("// A compilation error at this line likely means your copy of the")
        g.P("// proto package needs to be updated.")
        g.P("const _ = ", g.Pkg["proto"], ".ProtoPackageIsVersion", generatedCodeVersion, " // please upgrade the proto package")
        g.P()

        for _, td := range g.file.imp {
                g.generateImported(td)
        }
        for _, enum := range g.file.enum {
                g.generateEnum(enum)
        }
        for _, desc := range g.file.desc {
                // Don't generate virtual messages for maps.
                if desc.GetOptions().GetMapEntry() {
                        continue
                }
                g.generateMessage(desc)
        }
        for _, ext := range g.file.ext {
                g.generateExtension(ext)
        }
        g.generateInitFunction()
        g.generateFileDescriptor(file)

        // Run the plugins before the imports so we know which imports are necessary.
        g.runPlugins(file)

        // Generate header and imports last, though they appear first in the output.
        rem := g.Buffer
        remAnno := g.annotations
        g.Buffer = new(bytes.Buffer)
        g.annotations = nil
        g.generateHeader()
        g.generateImports()
        if !g.writeOutput {
                return
        }
        // Adjust the offsets for annotations displaced by the header and imports.
        for _, anno := range remAnno {
                *anno.Begin += int32(g.Len())
                *anno.End += int32(g.Len())
                g.annotations = append(g.annotations, anno)
        }
        g.Write(rem.Bytes())

        // Reformat generated code and patch annotation locations.
        fset := token.NewFileSet()
        original := g.Bytes()
        if g.annotateCode {
                // make a copy independent of g; we'll need it after Reset.
                original = append([]byte(nil), original...)
        }
        fileAST, 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())
                }
                g.Fail("bad Go source code was generated:", err.Error(), "\n"+src.String())
        }
        ast.SortImports(fset, fileAST)
        g.Reset()
        err = (&printer.Config{Mode: printer.TabIndent | printer.UseSpaces, Tabwidth: 8}).Fprint(g, fset, fileAST)
        if err != nil {
                g.Fail("generated Go source code could not be reformatted:", err.Error())
        }
        if g.annotateCode {
                m, err := remap.Compute(original, g.Bytes())
                if err != nil {
                        g.Fail("formatted generated Go source code could not be mapped back to the original code:", err.Error())
                }
                for _, anno := range g.annotations {
                        new, ok := m.Find(int(*anno.Begin), int(*anno.End))
                        if !ok {
                                g.Fail("span in formatted generated Go source code could not be mapped back to the original code")
                        }
                        *anno.Begin = int32(new.Pos)
                        *anno.End = int32(new.End)
                }
        }
}

// Generate the header, including package definition
func (g *Generator) generateHeader() {
        g.P("// Code generated by protoc-gen-go. DO NOT EDIT.")
        if g.file.GetOptions().GetDeprecated() {
                g.P("// ", g.file.Name, " is a deprecated file.")
        } else {
                g.P("// source: ", g.file.Name)
        }
        g.P()
        g.PrintComments(strconv.Itoa(packagePath))
        g.P()
        g.P("package ", g.file.packageName)
        g.P()
}

// deprecationComment is the standard comment added to deprecated
// messages, fields, enums, and enum values.
var deprecationComment = "// Deprecated: Do not use."

// PrintComments prints any comments from the source .proto file.
// The path is a comma-separated list of integers.
// It returns an indication of whether any comments were printed.
// See descriptor.proto for its format.
func (g *Generator) PrintComments(path string) bool {
        if !g.writeOutput {
                return false
        }
        if c, ok := g.makeComments(path); ok {
                g.P(c)
                return true
        }
        return false
}

// makeComments generates the comment string for the field, no "\n" at the end
func (g *Generator) makeComments(path string) (string, bool) {
        loc, ok := g.file.comments[path]
        if !ok {
                return "", false
        }
        w := new(bytes.Buffer)
        nl := ""
        for _, line := range strings.Split(strings.TrimSuffix(loc.GetLeadingComments(), "\n"), "\n") {
                fmt.Fprintf(w, "%s//%s", nl, line)
                nl = "\n"
        }
        return w.String(), true
}

func (g *Generator) fileByName(filename string) *FileDescriptor {
        return g.allFilesByName[filename]
}

// weak returns whether the ith import of the current file is a weak import.
func (g *Generator) weak(i int32) bool {
        for _, j := range g.file.WeakDependency {
                if j == i {
                        return true
                }
        }
        return false
}

// Generate the imports
func (g *Generator) generateImports() {
        imports := make(map[GoImportPath]GoPackageName)
        for i, s := range g.file.Dependency {
                fd := g.fileByName(s)
                importPath := fd.importPath
                // Do not import our own package.
                if importPath == g.file.importPath {
                        continue
                }
                // Do not import weak imports.
                if g.weak(int32(i)) {
                        continue
                }
                // Do not import a package twice.
                if _, ok := imports[importPath]; ok {
                        continue
                }
                // We need to import all the dependencies, even if we don't reference them,
                // because other code and tools depend on having the full transitive closure
                // of protocol buffer types in the binary.
                packageName := g.GoPackageName(importPath)
                if _, ok := g.usedPackages[importPath]; !ok {
                        packageName = "_"
                }
                imports[importPath] = packageName
        }
        for importPath := range g.addedImports {
                imports[importPath] = g.GoPackageName(importPath)
        }
        // We almost always need a proto import.  Rather than computing when we
        // do, which is tricky when there's a plugin, just import it and
        // reference it later. The same argument applies to the fmt and math packages.
        g.P("import (")
        g.P(g.Pkg["fmt"] + ` "fmt"`)
        g.P(g.Pkg["math"] + ` "math"`)
        g.P(g.Pkg["proto"]+" ", GoImportPath(g.ImportPrefix)+"github.com/golang/protobuf/proto")
        for importPath, packageName := range imports {
                g.P(packageName, " ", GoImportPath(g.ImportPrefix)+importPath)
        }
        g.P(")")
        g.P()
        // TODO: may need to worry about uniqueness across plugins
        for _, p := range plugins {
                p.GenerateImports(g.file)
                g.P()
        }
        g.P("// Reference imports to suppress errors if they are not otherwise used.")
        g.P("var _ = ", g.Pkg["proto"], ".Marshal")
        g.P("var _ = ", g.Pkg["fmt"], ".Errorf")
        g.P("var _ = ", g.Pkg["math"], ".Inf")
        g.P()
}

func (g *Generator) generateImported(id *ImportedDescriptor) {
        df := id.o.File()
        filename := *df.Name
        if df.importPath == g.file.importPath {
                // Don't generate type aliases for files in the same Go package as this one.
                return
        }
        if !supportTypeAliases {
                g.Fail(fmt.Sprintf("%s: public imports require at least go1.9", filename))
        }
        g.usedPackages[df.importPath] = true

        for _, sym := range df.exported[id.o] {
                sym.GenerateAlias(g, filename, g.GoPackageName(df.importPath))
        }

        g.P()
}

// Generate the enum definitions for this EnumDescriptor.
func (g *Generator) generateEnum(enum *EnumDescriptor) {
        // The full type name
        typeName := enum.TypeName()
        // The full type name, CamelCased.
        ccTypeName := CamelCaseSlice(typeName)
        ccPrefix := enum.prefix()

        deprecatedEnum := ""
        if enum.GetOptions().GetDeprecated() {
                deprecatedEnum = deprecationComment
        }
        g.PrintComments(enum.path)
        g.P("type ", Annotate(enum.file, enum.path, ccTypeName), " int32", deprecatedEnum)
        g.file.addExport(enum, enumSymbol{ccTypeName, enum.proto3()})
        g.P("const (")
        for i, e := range enum.Value {
                etorPath := fmt.Sprintf("%s,%d,%d", enum.path, enumValuePath, i)
                g.PrintComments(etorPath)

                deprecatedValue := ""
                if e.GetOptions().GetDeprecated() {
                        deprecatedValue = deprecationComment
                }

                name := ccPrefix + *e.Name
                g.P(Annotate(enum.file, etorPath, name), " ", ccTypeName, " = ", e.Number, " ", deprecatedValue)
                g.file.addExport(enum, constOrVarSymbol{name, "const", ccTypeName})
        }
        g.P(")")
        g.P()
        g.P("var ", ccTypeName, "_name = map[int32]string{")
        generated := make(map[int32]bool) // avoid duplicate values
        for _, e := range enum.Value {
                duplicate := ""
                if _, present := generated[*e.Number]; present {
                        duplicate = "// Duplicate value: "
                }
                g.P(duplicate, e.Number, ": ", strconv.Quote(*e.Name), ",")
                generated[*e.Number] = true
        }
        g.P("}")
        g.P()
        g.P("var ", ccTypeName, "_value = map[string]int32{")
        for _, e := range enum.Value {
                g.P(strconv.Quote(*e.Name), ": ", e.Number, ",")
        }
        g.P("}")
        g.P()

        if !enum.proto3() {
                g.P("func (x ", ccTypeName, ") Enum() *", ccTypeName, " {")
                g.P("p := new(", ccTypeName, ")")
                g.P("*p = x")
                g.P("return p")
                g.P("}")
                g.P()
        }

        g.P("func (x ", ccTypeName, ") String() string {")
        g.P("return ", g.Pkg["proto"], ".EnumName(", ccTypeName, "_name, int32(x))")
        g.P("}")
        g.P()

        if !enum.proto3() {
                g.P("func (x *", ccTypeName, ") UnmarshalJSON(data []byte) error {")
                g.P("value, err := ", g.Pkg["proto"], ".UnmarshalJSONEnum(", ccTypeName, `_value, data, "`, ccTypeName, `")`)
                g.P("if err != nil {")
                g.P("return err")
                g.P("}")
                g.P("*x = ", ccTypeName, "(value)")
                g.P("return nil")
                g.P("}")
                g.P()
        }

        var indexes []string
        for m := enum.parent; m != nil; m = m.parent {
                // XXX: skip groups?
                indexes = append([]string{strconv.Itoa(m.index)}, indexes...)
        }
        indexes = append(indexes, strconv.Itoa(enum.index))
        g.P("func (", ccTypeName, ") EnumDescriptor() ([]byte, []int) {")
        g.P("return ", g.file.VarName(), ", []int{", strings.Join(indexes, ", "), "}")
        g.P("}")
        g.P()
        if enum.file.GetPackage() == "google.protobuf" && enum.GetName() == "NullValue" {
                g.P("func (", ccTypeName, `) XXX_WellKnownType() string { return "`, enum.GetName(), `" }`)
                g.P()
        }

        g.generateEnumRegistration(enum)
}

// The tag is a string like "varint,2,opt,name=fieldname,def=7" that
// identifies details of the field for the protocol buffer marshaling and unmarshaling
// code.  The fields are:
//      wire encoding
//      protocol tag number
//      opt,req,rep for optional, required, or repeated
//      packed whether the encoding is "packed" (optional; repeated primitives only)
//      name= the original declared name
//      enum= the name of the enum type if it is an enum-typed field.
//      proto3 if this field is in a proto3 message
//      def= string representation of the default value, if any.
// The default value must be in a representation that can be used at run-time
// to generate the default value. Thus bools become 0 and 1, for instance.
func (g *Generator) goTag(message *Descriptor, field *descriptor.FieldDescriptorProto, wiretype string) string {
        optrepreq := ""
        switch {
        case isOptional(field):
                optrepreq = "opt"
        case isRequired(field):
                optrepreq = "req"
        case isRepeated(field):
                optrepreq = "rep"
        }
        var defaultValue string
        if dv := field.DefaultValue; dv != nil { // set means an explicit default
                defaultValue = *dv
                // Some types need tweaking.
                switch *field.Type {
                case descriptor.FieldDescriptorProto_TYPE_BOOL:
                        if defaultValue == "true" {
                                defaultValue = "1"
                        } else {
                                defaultValue = "0"
                        }
                case descriptor.FieldDescriptorProto_TYPE_STRING,
                        descriptor.FieldDescriptorProto_TYPE_BYTES:
                        // Nothing to do. Quoting is done for the whole tag.
                case descriptor.FieldDescriptorProto_TYPE_ENUM:
                        // For enums we need to provide the integer constant.
                        obj := g.ObjectNamed(field.GetTypeName())
                        if id, ok := obj.(*ImportedDescriptor); ok {
                                // It is an enum that was publicly imported.
                                // We need the underlying type.
                                obj = id.o
                        }
                        enum, ok := obj.(*EnumDescriptor)
                        if !ok {
                                log.Printf("obj is a %T", obj)
                                if id, ok := obj.(*ImportedDescriptor); ok {
                                        log.Printf("id.o is a %T", id.o)
                                }
                                g.Fail("unknown enum type", CamelCaseSlice(obj.TypeName()))
                        }
                        defaultValue = enum.integerValueAsString(defaultValue)
                case descriptor.FieldDescriptorProto_TYPE_FLOAT:
                        if def := defaultValue; def != "inf" && def != "-inf" && def != "nan" {
                                if f, err := strconv.ParseFloat(defaultValue, 32); err == nil {
                                        defaultValue = fmt.Sprint(float32(f))
                                }
                        }
                case descriptor.FieldDescriptorProto_TYPE_DOUBLE:
                        if def := defaultValue; def != "inf" && def != "-inf" && def != "nan" {
                                if f, err := strconv.ParseFloat(defaultValue, 64); err == nil {
                                        defaultValue = fmt.Sprint(f)
                                }
                        }
                }
                defaultValue = ",def=" + defaultValue
        }
        enum := ""
        if *field.Type == descriptor.FieldDescriptorProto_TYPE_ENUM {
                // We avoid using obj.GoPackageName(), because we want to use the
                // original (proto-world) package name.
                obj := g.ObjectNamed(field.GetTypeName())
                if id, ok := obj.(*ImportedDescriptor); ok {
                        obj = id.o
                }
                enum = ",enum="
                if pkg := obj.File().GetPackage(); pkg != "" {
                        enum += pkg + "."
                }
                enum += CamelCaseSlice(obj.TypeName())
        }
        packed := ""
        if (field.Options != nil && field.Options.GetPacked()) ||
                // Per https://developers.google.com/protocol-buffers/docs/proto3#simple:
                // "In proto3, repeated fields of scalar numeric types use packed encoding by default."
                (message.proto3() && (field.Options == nil || field.Options.Packed == nil) &&
                        isRepeated(field) && isScalar(field)) {
                packed = ",packed"
        }
        fieldName := field.GetName()
        name := fieldName
        if *field.Type == descriptor.FieldDescriptorProto_TYPE_GROUP {
                // We must use the type name for groups instead of
                // the field name to preserve capitalization.
                // type_name in FieldDescriptorProto is fully-qualified,
                // but we only want the local part.
                name = *field.TypeName
                if i := strings.LastIndex(name, "."); i >= 0 {
                        name = name[i+1:]
                }
        }
        if json := field.GetJsonName(); field.Extendee == nil && json != "" && json != name {
                // TODO: escaping might be needed, in which case
                // perhaps this should be in its own "json" tag.
                name += ",json=" + json
        }
        name = ",name=" + name
        if message.proto3() {
                name += ",proto3"
        }
        oneof := ""
        if field.OneofIndex != nil {
                oneof = ",oneof"
        }
        return strconv.Quote(fmt.Sprintf("%s,%d,%s%s%s%s%s%s",
                wiretype,
                field.GetNumber(),
                optrepreq,
                packed,
                name,
                enum,
                oneof,
                defaultValue))
}

func needsStar(typ descriptor.FieldDescriptorProto_Type) bool {
        switch typ {
        case descriptor.FieldDescriptorProto_TYPE_GROUP:
                return false
        case descriptor.FieldDescriptorProto_TYPE_MESSAGE:
                return false
        case descriptor.FieldDescriptorProto_TYPE_BYTES:
                return false
        }
        return true
}

// TypeName is the printed name appropriate for an item. If the object is in the current file,
// TypeName drops the package name and underscores the rest.
// Otherwise the object is from another package; and the result is the underscored
// package name followed by the item name.
// The result always has an initial capital.
func (g *Generator) TypeName(obj Object) string {
        return g.DefaultPackageName(obj) + CamelCaseSlice(obj.TypeName())
}

// GoType returns a string representing the type name, and the wire type
func (g *Generator) GoType(message *Descriptor, field *descriptor.FieldDescriptorProto) (typ string, wire string) {
        // TODO: Options.
        switch *field.Type {
        case descriptor.FieldDescriptorProto_TYPE_DOUBLE:
                typ, wire = "float64", "fixed64"
        case descriptor.FieldDescriptorProto_TYPE_FLOAT:
                typ, wire = "float32", "fixed32"
        case descriptor.FieldDescriptorProto_TYPE_INT64:
                typ, wire = "int64", "varint"
        case descriptor.FieldDescriptorProto_TYPE_UINT64:
                typ, wire = "uint64", "varint"
        case descriptor.FieldDescriptorProto_TYPE_INT32:
                typ, wire = "int32", "varint"
        case descriptor.FieldDescriptorProto_TYPE_UINT32:
                typ, wire = "uint32", "varint"
        case descriptor.FieldDescriptorProto_TYPE_FIXED64:
                typ, wire = "uint64", "fixed64"
        case descriptor.FieldDescriptorProto_TYPE_FIXED32:
                typ, wire = "uint32", "fixed32"
        case descriptor.FieldDescriptorProto_TYPE_BOOL:
                typ, wire = "bool", "varint"
        case descriptor.FieldDescriptorProto_TYPE_STRING:
                typ, wire = "string", "bytes"
        case descriptor.FieldDescriptorProto_TYPE_GROUP:
                desc := g.ObjectNamed(field.GetTypeName())
                typ, wire = "*"+g.TypeName(desc), "group"
        case descriptor.FieldDescriptorProto_TYPE_MESSAGE:
                desc := g.ObjectNamed(field.GetTypeName())
                typ, wire = "*"+g.TypeName(desc), "bytes"
        case descriptor.FieldDescriptorProto_TYPE_BYTES:
                typ, wire = "[]byte", "bytes"
        case descriptor.FieldDescriptorProto_TYPE_ENUM:
                desc := g.ObjectNamed(field.GetTypeName())
                typ, wire = g.TypeName(desc), "varint"
        case descriptor.FieldDescriptorProto_TYPE_SFIXED32:
                typ, wire = "int32", "fixed32"
        case descriptor.FieldDescriptorProto_TYPE_SFIXED64:
                typ, wire = "int64", "fixed64"
        case descriptor.FieldDescriptorProto_TYPE_SINT32:
                typ, wire = "int32", "zigzag32"
        case descriptor.FieldDescriptorProto_TYPE_SINT64:
                typ, wire = "int64", "zigzag64"
        default:
                g.Fail("unknown type for", field.GetName())
        }
        if isRepeated(field) {
                typ = "[]" + typ
        } else if message != nil && message.proto3() {
                return
        } else if field.OneofIndex != nil && message != nil {
                return
        } else if needsStar(*field.Type) {
                typ = "*" + typ
        }
        return
}

func (g *Generator) RecordTypeUse(t string) {
        if _, ok := g.typeNameToObject[t]; !ok {
                return
        }
        importPath := g.ObjectNamed(t).GoImportPath()
        if importPath == g.outputImportPath {
                // Don't record use of objects in our package.
                return
        }
        g.AddImport(importPath)
        g.usedPackages[importPath] = true
}

// Method names that may be generated.  Fields with these names get an
// underscore appended. Any change to this set is a potential incompatible
// API change because it changes generated field names.
var methodNames = [...]string{
        "Reset",
        "String",
        "ProtoMessage",
        "Marshal",
        "Unmarshal",
        "ExtensionRangeArray",
        "ExtensionMap",
        "Descriptor",
}

// Names of messages in the `google.protobuf` package for which
// we will generate XXX_WellKnownType methods.
var wellKnownTypes = map[string]bool{
        "Any":       true,
        "Duration":  true,
        "Empty":     true,
        "Struct":    true,
        "Timestamp": true,

        "Value":       true,
        "ListValue":   true,
        "DoubleValue": true,
        "FloatValue":  true,
        "Int64Value":  true,
        "UInt64Value": true,
        "Int32Value":  true,
        "UInt32Value": true,
        "BoolValue":   true,
        "StringValue": true,
        "BytesValue":  true,
}

// getterDefault finds the default value for the field to return from a getter,
// regardless of if it's a built in default or explicit from the source. Returns e.g. "nil", `""`, "Default_MessageType_FieldName"
func (g *Generator) getterDefault(field *descriptor.FieldDescriptorProto, goMessageType string) string {
        if isRepeated(field) {
                return "nil"
        }
        if def := field.GetDefaultValue(); def != "" {
                defaultConstant := g.defaultConstantName(goMessageType, field.GetName())
                if *field.Type != descriptor.FieldDescriptorProto_TYPE_BYTES {
                        return defaultConstant
                }
                return "append([]byte(nil), " + defaultConstant + "...)"
        }
        switch *field.Type {
        case descriptor.FieldDescriptorProto_TYPE_BOOL:
                return "false"
        case descriptor.FieldDescriptorProto_TYPE_STRING:
                return `""`
        case descriptor.FieldDescriptorProto_TYPE_GROUP, descriptor.FieldDescriptorProto_TYPE_MESSAGE, descriptor.FieldDescriptorProto_TYPE_BYTES:
                return "nil"
        case descriptor.FieldDescriptorProto_TYPE_ENUM:
                obj := g.ObjectNamed(field.GetTypeName())
                var enum *EnumDescriptor
                if id, ok := obj.(*ImportedDescriptor); ok {
                        // The enum type has been publicly imported.
                        enum, _ = id.o.(*EnumDescriptor)
                } else {
                        enum, _ = obj.(*EnumDescriptor)
                }
                if enum == nil {
                        log.Printf("don't know how to generate getter for %s", field.GetName())
                        return "nil"
                }
                if len(enum.Value) == 0 {
                        return "0 // empty enum"
                }
                first := enum.Value[0].GetName()
                return g.DefaultPackageName(obj) + enum.prefix() + first
        default:
                return "0"
        }
}

// defaultConstantName builds the name of the default constant from the message
// type name and the untouched field name, e.g. "Default_MessageType_FieldName"
func (g *Generator) defaultConstantName(goMessageType, protoFieldName string) string {
        return "Default_" + goMessageType + "_" + CamelCase(protoFieldName)
}

// The different types of fields in a message and how to actually print them
// Most of the logic for generateMessage is in the methods of these types.
//
// Note that the content of the field is irrelevant, a simpleField can contain
// anything from a scalar to a group (which is just a message).
//
// Extension fields (and message sets) are however handled separately.
//
// simpleField - a field that is neiter weak nor oneof, possibly repeated
// oneofField - field containing list of subfields:
// - oneofSubField - a field within the oneof

// msgCtx contains the context for the generator functions.
type msgCtx struct {
        goName  string      // Go struct name of the message, e.g. MessageName
        message *Descriptor // The descriptor for the message
}

// fieldCommon contains data common to all types of fields.
type fieldCommon struct {
        goName     string // Go name of field, e.g. "FieldName" or "Descriptor_"
        protoName  string // Name of field in proto language, e.g. "field_name" or "descriptor"
        getterName string // Name of the getter, e.g. "GetFieldName" or "GetDescriptor_"
        goType     string // The Go type as a string, e.g. "*int32" or "*OtherMessage"
        tags       string // The tag string/annotation for the type, e.g. `protobuf:"varint,8,opt,name=region_id,json=regionId"`
        fullPath   string // The full path of the field as used by Annotate etc, e.g. "4,0,2,0"
}

// getProtoName gets the proto name of a field, e.g. "field_name" or "descriptor".
func (f *fieldCommon) getProtoName() string {
        return f.protoName
}

// getGoType returns the go type of the field  as a string, e.g. "*int32".
func (f *fieldCommon) getGoType() string {
        return f.goType
}

// simpleField is not weak, not a oneof, not an extension. Can be required, optional or repeated.
type simpleField struct {
        fieldCommon
        protoTypeName string                               // Proto type name, empty if primitive, e.g. ".google.protobuf.Duration"
        protoType     descriptor.FieldDescriptorProto_Type // Actual type enum value, e.g. descriptor.FieldDescriptorProto_TYPE_FIXED64
        deprecated    string                               // Deprecation comment, if any, e.g. "// Deprecated: Do not use."
        getterDef     string                               // Default for getters, e.g. "nil", `""` or "Default_MessageType_FieldName"
        protoDef      string                               // Default value as defined in the proto file, e.g "yoshi" or "5"
        comment       string                               // The full comment for the field, e.g. "// Useful information"
}

// decl prints the declaration of the field in the struct (if any).
func (f *simpleField) decl(g *Generator, mc *msgCtx) {
        g.P(f.comment, Annotate(mc.message.file, f.fullPath, f.goName), "\t", f.goType, "\t`", f.tags, "`", f.deprecated)
}

// getter prints the getter for the field.
func (f *simpleField) getter(g *Generator, mc *msgCtx) {
        star := ""
        tname := f.goType
        if needsStar(f.protoType) && tname[0] == '*' {
                tname = tname[1:]
                star = "*"
        }
        if f.deprecated != "" {
                g.P(f.deprecated)
        }
        g.P("func (m *", mc.goName, ") ", Annotate(mc.message.file, f.fullPath, f.getterName), "() "+tname+" {")
        if f.getterDef == "nil" { // Simpler getter
                g.P("if m != nil {")
                g.P("return m." + f.goName)
                g.P("}")
                g.P("return nil")
                g.P("}")
                g.P()
                return
        }
        if mc.message.proto3() {
                g.P("if m != nil {")
        } else {
                g.P("if m != nil && m." + f.goName + " != nil {")
        }
        g.P("return " + star + "m." + f.goName)
        g.P("}")
        g.P("return ", f.getterDef)
        g.P("}")
        g.P()
}

// setter prints the setter method of the field.
func (f *simpleField) setter(g *Generator, mc *msgCtx) {
        // No setter for regular fields yet
}

// getProtoDef returns the default value explicitly stated in the proto file, e.g "yoshi" or "5".
func (f *simpleField) getProtoDef() string {
        return f.protoDef
}

// getProtoTypeName returns the protobuf type name for the field as returned by field.GetTypeName(), e.g. ".google.protobuf.Duration".
func (f *simpleField) getProtoTypeName() string {
        return f.protoTypeName
}

// getProtoType returns the *field.Type value, e.g. descriptor.FieldDescriptorProto_TYPE_FIXED64.
func (f *simpleField) getProtoType() descriptor.FieldDescriptorProto_Type {
        return f.protoType
}

// oneofSubFields are kept slize held by each oneofField. They do not appear in the top level slize of fields for the message.
type oneofSubField struct {
        fieldCommon
        protoTypeName string                               // Proto type name, empty if primitive, e.g. ".google.protobuf.Duration"
        protoType     descriptor.FieldDescriptorProto_Type // Actual type enum value, e.g. descriptor.FieldDescriptorProto_TYPE_FIXED64
        oneofTypeName string                               // Type name of the enclosing struct, e.g. "MessageName_FieldName"
        fieldNumber   int                                  // Actual field number, as defined in proto, e.g. 12
        getterDef     string                               // Default for getters, e.g. "nil", `""` or "Default_MessageType_FieldName"
        protoDef      string                               // Default value as defined in the proto file, e.g "yoshi" or "5"
        deprecated    string                               // Deprecation comment, if any.
}

// typedNil prints a nil casted to the pointer to this field.
// - for XXX_OneofWrappers
func (f *oneofSubField) typedNil(g *Generator) {
        g.P("(*", f.oneofTypeName, ")(nil),")
}

// getProtoDef returns the default value explicitly stated in the proto file, e.g "yoshi" or "5".
func (f *oneofSubField) getProtoDef() string {
        return f.protoDef
}

// getProtoTypeName returns the protobuf type name for the field as returned by field.GetTypeName(), e.g. ".google.protobuf.Duration".
func (f *oneofSubField) getProtoTypeName() string {
        return f.protoTypeName
}

// getProtoType returns the *field.Type value, e.g. descriptor.FieldDescriptorProto_TYPE_FIXED64.
func (f *oneofSubField) getProtoType() descriptor.FieldDescriptorProto_Type {
        return f.protoType
}

// oneofField represents the oneof on top level.
// The alternative fields within the oneof are represented by oneofSubField.
type oneofField struct {
        fieldCommon
        subFields []*oneofSubField // All the possible oneof fields
        comment   string           // The full comment for the field, e.g. "// Types that are valid to be assigned to MyOneof:\n\\"
}

// decl prints the declaration of the field in the struct (if any).
func (f *oneofField) decl(g *Generator, mc *msgCtx) {
        comment := f.comment
        for _, sf := range f.subFields {
                comment += "//\t*" + sf.oneofTypeName + "\n"
        }
        g.P(comment, Annotate(mc.message.file, f.fullPath, f.goName), " ", f.goType, " `", f.tags, "`")
}

// getter for a oneof field will print additional discriminators and interfaces for the oneof,
// also it prints all the getters for the sub fields.
func (f *oneofField) getter(g *Generator, mc *msgCtx) {
        // The discriminator type
        g.P("type ", f.goType, " interface {")
        g.P(f.goType, "()")
        g.P("}")
        g.P()
        // The subField types, fulfilling the discriminator type contract
        for _, sf := range f.subFields {
                g.P("type ", Annotate(mc.message.file, sf.fullPath, sf.oneofTypeName), " struct {")
                g.P(Annotate(mc.message.file, sf.fullPath, sf.goName), " ", sf.goType, " `", sf.tags, "`")
                g.P("}")
                g.P()
        }
        for _, sf := range f.subFields {
                g.P("func (*", sf.oneofTypeName, ") ", f.goType, "() {}")
                g.P()
        }
        // Getter for the oneof field
        g.P("func (m *", mc.goName, ") ", Annotate(mc.message.file, f.fullPath, f.getterName), "() ", f.goType, " {")
        g.P("if m != nil { return m.", f.goName, " }")
        g.P("return nil")
        g.P("}")
        g.P()
        // Getters for each oneof
        for _, sf := range f.subFields {
                if sf.deprecated != "" {
                        g.P(sf.deprecated)
                }
                g.P("func (m *", mc.goName, ") ", Annotate(mc.message.file, sf.fullPath, sf.getterName), "() "+sf.goType+" {")
                g.P("if x, ok := m.", f.getterName, "().(*", sf.oneofTypeName, "); ok {")
                g.P("return x.", sf.goName)
                g.P("}")
                g.P("return ", sf.getterDef)
                g.P("}")
                g.P()
        }
}

// setter prints the setter method of the field.
func (f *oneofField) setter(g *Generator, mc *msgCtx) {
        // No setters for oneof yet
}

// topLevelField interface implemented by all types of fields on the top level (not oneofSubField).
type topLevelField interface {
        decl(g *Generator, mc *msgCtx)   // print declaration within the struct
        getter(g *Generator, mc *msgCtx) // print getter
        setter(g *Generator, mc *msgCtx) // print setter if applicable
}

// defField interface implemented by all types of fields that can have defaults (not oneofField, but instead oneofSubField).
type defField interface {
        getProtoDef() string                                // default value explicitly stated in the proto file, e.g "yoshi" or "5"
        getProtoName() string                               // proto name of a field, e.g. "field_name" or "descriptor"
        getGoType() string                                  // go type of the field  as a string, e.g. "*int32"
        getProtoTypeName() string                           // protobuf type name for the field, e.g. ".google.protobuf.Duration"
        getProtoType() descriptor.FieldDescriptorProto_Type // *field.Type value, e.g. descriptor.FieldDescriptorProto_TYPE_FIXED64
}

// generateDefaultConstants adds constants for default values if needed, which is only if the default value is.
// explicit in the proto.
func (g *Generator) generateDefaultConstants(mc *msgCtx, topLevelFields []topLevelField) {
        // Collect fields that can have defaults
        dFields := []defField{}
        for _, pf := range topLevelFields {
                if f, ok := pf.(*oneofField); ok {
                        for _, osf := range f.subFields {
                                dFields = append(dFields, osf)
                        }
                        continue
                }
                dFields = append(dFields, pf.(defField))
        }
        for _, df := range dFields {
                def := df.getProtoDef()
                if def == "" {
                        continue
                }
                fieldname := g.defaultConstantName(mc.goName, df.getProtoName())
                typename := df.getGoType()
                if typename[0] == '*' {
                        typename = typename[1:]
                }
                kind := "const "
                switch {
                case typename == "bool":
                case typename == "string":
                        def = strconv.Quote(def)
                case typename == "[]byte":
                        def = "[]byte(" + strconv.Quote(unescape(def)) + ")"
                        kind = "var "
                case def == "inf", def == "-inf", def == "nan":
                        // These names are known to, and defined by, the protocol language.
                        switch def {
                        case "inf":
                                def = "math.Inf(1)"
                        case "-inf":
                                def = "math.Inf(-1)"
                        case "nan":
                                def = "math.NaN()"
                        }
                        if df.getProtoType() == descriptor.FieldDescriptorProto_TYPE_FLOAT {
                                def = "float32(" + def + ")"
                        }
                        kind = "var "
                case df.getProtoType() == descriptor.FieldDescriptorProto_TYPE_FLOAT:
                        if f, err := strconv.ParseFloat(def, 32); err == nil {
                                def = fmt.Sprint(float32(f))
                        }
                case df.getProtoType() == descriptor.FieldDescriptorProto_TYPE_DOUBLE:
                        if f, err := strconv.ParseFloat(def, 64); err == nil {
                                def = fmt.Sprint(f)
                        }
                case df.getProtoType() == descriptor.FieldDescriptorProto_TYPE_ENUM:
                        // Must be an enum.  Need to construct the prefixed name.
                        obj := g.ObjectNamed(df.getProtoTypeName())
                        var enum *EnumDescriptor
                        if id, ok := obj.(*ImportedDescriptor); ok {
                                // The enum type has been publicly imported.
                                enum, _ = id.o.(*EnumDescriptor)
                        } else {
                                enum, _ = obj.(*EnumDescriptor)
                        }
                        if enum == nil {
                                log.Printf("don't know how to generate constant for %s", fieldname)
                                continue
                        }
                        def = g.DefaultPackageName(obj) + enum.prefix() + def
                }
                g.P(kind, fieldname, " ", typename, " = ", def)
                g.file.addExport(mc.message, constOrVarSymbol{fieldname, kind, ""})
        }
        g.P()
}

// generateInternalStructFields just adds the XXX_<something> fields to the message struct.
func (g *Generator) generateInternalStructFields(mc *msgCtx, topLevelFields []topLevelField) {
        g.P("XXX_NoUnkeyedLiteral\tstruct{} `json:\"-\"`") // prevent unkeyed struct literals
        if len(mc.message.ExtensionRange) > 0 {
                messageset := ""
                if opts := mc.message.Options; opts != nil && opts.GetMessageSetWireFormat() {
                        messageset = "protobuf_messageset:\"1\" "
                }
                g.P(g.Pkg["proto"], ".XXX_InternalExtensions `", messageset, "json:\"-\"`")
        }
        g.P("XXX_unrecognized\t[]byte `json:\"-\"`")
        g.P("XXX_sizecache\tint32 `json:\"-\"`")

}

// generateOneofFuncs adds all the utility functions for oneof, including marshalling, unmarshalling and sizer.
func (g *Generator) generateOneofFuncs(mc *msgCtx, topLevelFields []topLevelField) {
        ofields := []*oneofField{}
        for _, f := range topLevelFields {
                if o, ok := f.(*oneofField); ok {
                        ofields = append(ofields, o)
                }
        }
        if len(ofields) == 0 {
                return
        }

        // OneofFuncs
        g.P("// XXX_OneofWrappers is for the internal use of the proto package.")
        g.P("func (*", mc.goName, ") XXX_OneofWrappers() []interface{} {")
        g.P("return []interface{}{")
        for _, of := range ofields {
                for _, sf := range of.subFields {
                        sf.typedNil(g)
                }
        }
        g.P("}")
        g.P("}")
        g.P()
}

// generateMessageStruct adds the actual struct with it's members (but not methods) to the output.
func (g *Generator) generateMessageStruct(mc *msgCtx, topLevelFields []topLevelField) {
        comments := g.PrintComments(mc.message.path)

        // Guarantee deprecation comments appear after user-provided comments.
        if mc.message.GetOptions().GetDeprecated() {
                if comments {
                        // Convention: Separate deprecation comments from original
                        // comments with an empty line.
                        g.P("//")
                }
                g.P(deprecationComment)
        }

        g.P("type ", Annotate(mc.message.file, mc.message.path, mc.goName), " struct {")
        for _, pf := range topLevelFields {
                pf.decl(g, mc)
        }
        g.generateInternalStructFields(mc, topLevelFields)
        g.P("}")
}

// generateGetters adds getters for all fields, including oneofs and weak fields when applicable.
func (g *Generator) generateGetters(mc *msgCtx, topLevelFields []topLevelField) {
        for _, pf := range topLevelFields {
                pf.getter(g, mc)
        }
}

// generateSetters add setters for all fields, including oneofs and weak fields when applicable.
func (g *Generator) generateSetters(mc *msgCtx, topLevelFields []topLevelField) {
        for _, pf := range topLevelFields {
                pf.setter(g, mc)
        }
}

// generateCommonMethods adds methods to the message that are not on a per field basis.
func (g *Generator) generateCommonMethods(mc *msgCtx) {
        // Reset, String and ProtoMessage methods.
        g.P("func (m *", mc.goName, ") Reset() { *m = ", mc.goName, "{} }")
        g.P("func (m *", mc.goName, ") String() string { return ", g.Pkg["proto"], ".CompactTextString(m) }")
        g.P("func (*", mc.goName, ") ProtoMessage() {}")
        var indexes []string
        for m := mc.message; m != nil; m = m.parent {
                indexes = append([]string{strconv.Itoa(m.index)}, indexes...)
        }
        g.P("func (*", mc.goName, ") Descriptor() ([]byte, []int) {")
        g.P("return ", g.file.VarName(), ", []int{", strings.Join(indexes, ", "), "}")
        g.P("}")
        g.P()
        // TODO: Revisit the decision to use a XXX_WellKnownType method
        // if we change proto.MessageName to work with multiple equivalents.
        if mc.message.file.GetPackage() == "google.protobuf" && wellKnownTypes[mc.message.GetName()] {
                g.P("func (*", mc.goName, `) XXX_WellKnownType() string { return "`, mc.message.GetName(), `" }`)
                g.P()
        }

        // Extension support methods
        if len(mc.message.ExtensionRange) > 0 {
                g.P()
                g.P("var extRange_", mc.goName, " = []", g.Pkg["proto"], ".ExtensionRange{")
                for _, r := range mc.message.ExtensionRange {
                        end := fmt.Sprint(*r.End - 1) // make range inclusive on both ends
                        g.P("{Start: ", r.Start, ", End: ", end, "},")
                }
                g.P("}")
                g.P("func (*", mc.goName, ") ExtensionRangeArray() []", g.Pkg["proto"], ".ExtensionRange {")
                g.P("return extRange_", mc.goName)
                g.P("}")
                g.P()
        }

        // TODO: It does not scale to keep adding another method for every
        // operation on protos that we want to switch over to using the
        // table-driven approach. Instead, we should only add a single method
        // that allows getting access to the *InternalMessageInfo struct and then
        // calling Unmarshal, Marshal, Merge, Size, and Discard directly on that.

        // Wrapper for table-driven marshaling and unmarshaling.
        g.P("func (m *", mc.goName, ") XXX_Unmarshal(b []byte) error {")
        g.P("return xxx_messageInfo_", mc.goName, ".Unmarshal(m, b)")
        g.P("}")

        g.P("func (m *", mc.goName, ") XXX_Marshal(b []byte, deterministic bool) ([]byte, error) {")
        g.P("return xxx_messageInfo_", mc.goName, ".Marshal(b, m, deterministic)")
        g.P("}")

        g.P("func (m *", mc.goName, ") XXX_Merge(src ", g.Pkg["proto"], ".Message) {")
        g.P("xxx_messageInfo_", mc.goName, ".Merge(m, src)")
        g.P("}")

        g.P("func (m *", mc.goName, ") XXX_Size() int {") // avoid name clash with "Size" field in some message
        g.P("return xxx_messageInfo_", mc.goName, ".Size(m)")
        g.P("}")

        g.P("func (m *", mc.goName, ") XXX_DiscardUnknown() {")
        g.P("xxx_messageInfo_", mc.goName, ".DiscardUnknown(m)")
        g.P("}")

        g.P("var xxx_messageInfo_", mc.goName, " ", g.Pkg["proto"], ".InternalMessageInfo")
        g.P()
}

// Generate the type, methods and default constant definitions for this Descriptor.
func (g *Generator) generateMessage(message *Descriptor) {
        topLevelFields := []topLevelField{}
        oFields := make(map[int32]*oneofField)
        // The full type name
        typeName := message.TypeName()
        // The full type name, CamelCased.
        goTypeName := CamelCaseSlice(typeName)

        usedNames := make(map[string]bool)
        for _, n := range methodNames {
                usedNames[n] = true
        }

        // allocNames finds a conflict-free variation of the given strings,
        // consistently mutating their suffixes.
        // It returns the same number of strings.
        allocNames := func(ns ...string) []string {
        Loop:
                for {
                        for _, n := range ns {
                                if usedNames[n] {
                                        for i := range ns {
                                                ns[i] += "_"
                                        }
                                        continue Loop
                                }
                        }
                        for _, n := range ns {
                                usedNames[n] = true
                        }
                        return ns
                }
        }

        mapFieldTypes := make(map[*descriptor.FieldDescriptorProto]string) // keep track of the map fields to be added later

        // Build a structure more suitable for generating the text in one pass
        for i, field := range message.Field {
                // Allocate the getter and the field at the same time so name
                // collisions create field/method consistent names.
                // TODO: This allocation occurs based on the order of the fields
                // in the proto file, meaning that a change in the field
                // ordering can change generated Method/Field names.
                base := CamelCase(*field.Name)
                ns := allocNames(base, "Get"+base)
                fieldName, fieldGetterName := ns[0], ns[1]
                typename, wiretype := g.GoType(message, field)
                jsonName := *field.Name
                tag := fmt.Sprintf("protobuf:%s json:%q", g.goTag(message, field, wiretype), jsonName+",omitempty")

                oneof := field.OneofIndex != nil
                if oneof && oFields[*field.OneofIndex] == nil {
                        odp := message.OneofDecl[int(*field.OneofIndex)]
                        base := CamelCase(odp.GetName())
                        fname := allocNames(base)[0]

                        // This is the first field of a oneof we haven't seen before.
                        // Generate the union field.
                        oneofFullPath := fmt.Sprintf("%s,%d,%d", message.path, messageOneofPath, *field.OneofIndex)
                        c, ok := g.makeComments(oneofFullPath)
                        if ok {
                                c += "\n//\n"
                        }
                        c += "// Types that are valid to be assigned to " + fname + ":\n"
                        // Generate the rest of this comment later,
                        // when we've computed any disambiguation.

                        dname := "is" + goTypeName + "_" + fname
                        tag := `protobuf_oneof:"` + odp.GetName() + `"`
                        of := oneofField{
                                fieldCommon: fieldCommon{
                                        goName:     fname,
                                        getterName: "Get"+fname,
                                        goType:     dname,
                                        tags:       tag,
                                        protoName:  odp.GetName(),
                                        fullPath:   oneofFullPath,
                                },
                                comment: c,
                        }
                        topLevelFields = append(topLevelFields, &of)
                        oFields[*field.OneofIndex] = &of
                }

                if *field.Type == descriptor.FieldDescriptorProto_TYPE_MESSAGE {
                        desc := g.ObjectNamed(field.GetTypeName())
                        if d, ok := desc.(*Descriptor); ok && d.GetOptions().GetMapEntry() {
                                // Figure out the Go types and tags for the key and value types.
                                keyField, valField := d.Field[0], d.Field[1]
                                keyType, keyWire := g.GoType(d, keyField)
                                valType, valWire := g.GoType(d, valField)
                                keyTag, valTag := g.goTag(d, keyField, keyWire), g.goTag(d, valField, valWire)

                                // We don't use stars, except for message-typed values.
                                // Message and enum types are the only two possibly foreign types used in maps,
                                // so record their use. They are not permitted as map keys.
                                keyType = strings.TrimPrefix(keyType, "*")
                                switch *valField.Type {
                                case descriptor.FieldDescriptorProto_TYPE_ENUM:
                                        valType = strings.TrimPrefix(valType, "*")
                                        g.RecordTypeUse(valField.GetTypeName())
                                case descriptor.FieldDescriptorProto_TYPE_MESSAGE:
                                        g.RecordTypeUse(valField.GetTypeName())
                                default:
                                        valType = strings.TrimPrefix(valType, "*")
                                }

                                typename = fmt.Sprintf("map[%s]%s", keyType, valType)
                                mapFieldTypes[field] = typename // record for the getter generation

                                tag += fmt.Sprintf(" protobuf_key:%s protobuf_val:%s", keyTag, valTag)
                        }
                }

                fieldDeprecated := ""
                if field.GetOptions().GetDeprecated() {
                        fieldDeprecated = deprecationComment
                }

                dvalue := g.getterDefault(field, goTypeName)
                if oneof {
                        tname := goTypeName + "_" + fieldName
                        // It is possible for this to collide with a message or enum
                        // nested in this message. Check for collisions.
                        for {
                                ok := true
                                for _, desc := range message.nested {
                                        if CamelCaseSlice(desc.TypeName()) == tname {
                                                ok = false
                                                break
                                        }
                                }
                                for _, enum := range message.enums {
                                        if CamelCaseSlice(enum.TypeName()) == tname {
                                                ok = false
                                                break
                                        }
                                }
                                if !ok {
                                        tname += "_"
                                        continue
                                }
                                break
                        }

                        oneofField := oFields[*field.OneofIndex]
                        tag := "protobuf:" + g.goTag(message, field, wiretype)
                        sf := oneofSubField{
                                fieldCommon: fieldCommon{
                                        goName:     fieldName,
                                        getterName: fieldGetterName,
                                        goType:     typename,
                                        tags:       tag,
                                        protoName:  field.GetName(),
                                        fullPath:   fmt.Sprintf("%s,%d,%d", message.path, messageFieldPath, i),
                                },
                                protoTypeName: field.GetTypeName(),
                                fieldNumber:   int(*field.Number),
                                protoType:     *field.Type,
                                getterDef:     dvalue,
                                protoDef:      field.GetDefaultValue(),
                                oneofTypeName: tname,
                                deprecated:    fieldDeprecated,
                        }
                        oneofField.subFields = append(oneofField.subFields, &sf)
                        g.RecordTypeUse(field.GetTypeName())
                        continue
                }

                fieldFullPath := fmt.Sprintf("%s,%d,%d", message.path, messageFieldPath, i)
                c, ok := g.makeComments(fieldFullPath)
                if ok {
                        c += "\n"
                }
                rf := simpleField{
                        fieldCommon: fieldCommon{
                                goName:     fieldName,
                                getterName: fieldGetterName,
                                goType:     typename,
                                tags:       tag,
                                protoName:  field.GetName(),
                                fullPath:   fieldFullPath,
                        },
                        protoTypeName: field.GetTypeName(),
                        protoType:     *field.Type,
                        deprecated:    fieldDeprecated,
                        getterDef:     dvalue,
                        protoDef:      field.GetDefaultValue(),
                        comment:       c,
                }
                var pf topLevelField = &rf

                topLevelFields = append(topLevelFields, pf)
                g.RecordTypeUse(field.GetTypeName())
        }

        mc := &msgCtx{
                goName:  goTypeName,
                message: message,
        }

        g.generateMessageStruct(mc, topLevelFields)
        g.P()
        g.generateCommonMethods(mc)
        g.P()
        g.generateDefaultConstants(mc, topLevelFields)
        g.P()
        g.generateGetters(mc, topLevelFields)
        g.P()
        g.generateSetters(mc, topLevelFields)
        g.P()
        g.generateOneofFuncs(mc, topLevelFields)
        g.P()

        var oneofTypes []string
        for _, f := range topLevelFields {
                if of, ok := f.(*oneofField); ok {
                        for _, osf := range of.subFields {
                                oneofTypes = append(oneofTypes, osf.oneofTypeName)
                        }
                }
        }

        opts := message.Options
        ms := &messageSymbol{
                sym:           goTypeName,
                hasExtensions: len(message.ExtensionRange) > 0,
                isMessageSet:  opts != nil && opts.GetMessageSetWireFormat(),
                oneofTypes:    oneofTypes,
        }
        g.file.addExport(message, ms)

        for _, ext := range message.ext {
                g.generateExtension(ext)
        }

        fullName := strings.Join(message.TypeName(), ".")
        if g.file.Package != nil {
                fullName = *g.file.Package + "." + fullName
        }

        g.addInitf("%s.RegisterType((*%s)(nil), %q)", g.Pkg["proto"], goTypeName, fullName)
        // Register types for native map types.
        for _, k := range mapFieldKeys(mapFieldTypes) {
                fullName := strings.TrimPrefix(*k.TypeName, ".")
                g.addInitf("%s.RegisterMapType((%s)(nil), %q)", g.Pkg["proto"], mapFieldTypes[k], fullName)
        }

}

type byTypeName []*descriptor.FieldDescriptorProto

func (a byTypeName) Len() int           { return len(a) }
func (a byTypeName) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }
func (a byTypeName) Less(i, j int) bool { return *a[i].TypeName < *a[j].TypeName }

// mapFieldKeys returns the keys of m in a consistent order.
func mapFieldKeys(m map[*descriptor.FieldDescriptorProto]string) []*descriptor.FieldDescriptorProto {
        keys := make([]*descriptor.FieldDescriptorProto, 0, len(m))
        for k := range m {
                keys = append(keys, k)
        }
        sort.Sort(byTypeName(keys))
        return keys
}

var escapeChars = [256]byte{
        'a': '\a', 'b': '\b', 'f': '\f', 'n': '\n', 'r': '\r', 't': '\t', 'v': '\v', '\\': '\\', '"': '"', '\'': '\'', '?': '?',
}

// unescape reverses the "C" escaping that protoc does for default values of bytes fields.
// It is best effort in that it effectively ignores malformed input. Seemingly invalid escape
// sequences are conveyed, unmodified, into the decoded result.
func unescape(s string) string {
        // NB: Sadly, we can't use strconv.Unquote because protoc will escape both
        // single and double quotes, but strconv.Unquote only allows one or the
        // other (based on actual surrounding quotes of its input argument).

        var out []byte
        for len(s) > 0 {
                // regular character, or too short to be valid escape
                if s[0] != '\\' || len(s) < 2 {
                        out = append(out, s[0])
                        s = s[1:]
                } else if c := escapeChars[s[1]]; c != 0 {
                        // escape sequence
                        out = append(out, c)
                        s = s[2:]
                } else if s[1] == 'x' || s[1] == 'X' {
                        // hex escape, e.g. "\x80
                        if len(s) < 4 {
                                // too short to be valid
                                out = append(out, s[:2]...)
                                s = s[2:]
                                continue
                        }
                        v, err := strconv.ParseUint(s[2:4], 16, 8)
                        if err != nil {
                                out = append(out, s[:4]...)
                        } else {
                                out = append(out, byte(v))
                        }
                        s = s[4:]
                } else if '0' <= s[1] && s[1] <= '7' {
                        // octal escape, can vary from 1 to 3 octal digits; e.g., "\0" "\40" or "\164"
                        // so consume up to 2 more bytes or up to end-of-string
                        n := len(s[1:]) - len(strings.TrimLeft(s[1:], "01234567"))
                        if n > 3 {
                                n = 3
                        }
                        v, err := strconv.ParseUint(s[1:1+n], 8, 8)
                        if err != nil {
                                out = append(out, s[:1+n]...)
                        } else {
                                out = append(out, byte(v))
                        }
                        s = s[1+n:]
                } else {
                        // bad escape, just propagate the slash as-is
                        out = append(out, s[0])
                        s = s[1:]
                }
        }

        return string(out)
}

func (g *Generator) generateExtension(ext *ExtensionDescriptor) {
        ccTypeName := ext.DescName()

        extObj := g.ObjectNamed(*ext.Extendee)
        var extDesc *Descriptor
        if id, ok := extObj.(*ImportedDescriptor); ok {
                // This is extending a publicly imported message.
                // We need the underlying type for goTag.
                extDesc = id.o.(*Descriptor)
        } else {
                extDesc = extObj.(*Descriptor)
        }
        extendedType := "*" + g.TypeName(extObj) // always use the original
        field := ext.FieldDescriptorProto
        fieldType, wireType := g.GoType(ext.parent, field)
        tag := g.goTag(extDesc, field, wireType)
        g.RecordTypeUse(*ext.Extendee)
        if n := ext.FieldDescriptorProto.TypeName; n != nil {
                // foreign extension type
                g.RecordTypeUse(*n)
        }

        typeName := ext.TypeName()

        // Special case for proto2 message sets: If this extension is extending
        // proto2.bridge.MessageSet, and its final name component is "message_set_extension",
        // then drop that last component.
        //
        // TODO: This should be implemented in the text formatter rather than the generator.
        // In addition, the situation for when to apply this special case is implemented
        // differently in other languages:
        // https://github.com/google/protobuf/blob/aff10976/src/google/protobuf/text_format.cc#L1560
        if extDesc.GetOptions().GetMessageSetWireFormat() && typeName[len(typeName)-1] == "message_set_extension" {
                typeName = typeName[:len(typeName)-1]
        }

        // For text formatting, the package must be exactly what the .proto file declares,
        // ignoring overrides such as the go_package option, and with no dot/underscore mapping.
        extName := strings.Join(typeName, ".")
        if g.file.Package != nil {
                extName = *g.file.Package + "." + extName
        }

        g.P("var ", ccTypeName, " = &", g.Pkg["proto"], ".ExtensionDesc{")
        g.P("ExtendedType: (", extendedType, ")(nil),")
        g.P("ExtensionType: (", fieldType, ")(nil),")
        g.P("Field: ", field.Number, ",")
        g.P(`Name: "`, extName, `",`)
        g.P("Tag: ", tag, ",")
        g.P(`Filename: "`, g.file.GetName(), `",`)

        g.P("}")
        g.P()

        g.addInitf("%s.RegisterExtension(%s)", g.Pkg["proto"], ext.DescName())

        g.file.addExport(ext, constOrVarSymbol{ccTypeName, "var", ""})
}

func (g *Generator) generateInitFunction() {
        if len(g.init) == 0 {
                return
        }
        g.P("func init() {")
        for _, l := range g.init {
                g.P(l)
        }
        g.P("}")
        g.init = nil
}

func (g *Generator) generateFileDescriptor(file *FileDescriptor) {
        // Make a copy and trim source_code_info data.
        // TODO: Trim this more when we know exactly what we need.
        pb := proto.Clone(file.FileDescriptorProto).(*descriptor.FileDescriptorProto)
        pb.SourceCodeInfo = nil

        b, err := proto.Marshal(pb)
        if err != nil {
                g.Fail(err.Error())
        }

        var buf bytes.Buffer
        w, _ := gzip.NewWriterLevel(&buf, gzip.BestCompression)
        w.Write(b)
        w.Close()
        b = buf.Bytes()

        v := file.VarName()
        g.P()
        g.P("func init() { ", g.Pkg["proto"], ".RegisterFile(", strconv.Quote(*file.Name), ", ", v, ") }")
        g.P("var ", v, " = []byte{")
        g.P("// ", len(b), " bytes of a gzipped FileDescriptorProto")
        for len(b) > 0 {
                n := 16
                if n > len(b) {
                        n = len(b)
                }

                s := ""
                for _, c := range b[:n] {
                        s += fmt.Sprintf("0x%02x,", c)
                }
                g.P(s)

                b = b[n:]
        }
        g.P("}")
}

func (g *Generator) generateEnumRegistration(enum *EnumDescriptor) {
        // // We always print the full (proto-world) package name here.
        pkg := enum.File().GetPackage()
        if pkg != "" {
                pkg += "."
        }
        // The full type name
        typeName := enum.TypeName()
        // The full type name, CamelCased.
        ccTypeName := CamelCaseSlice(typeName)
        g.addInitf("%s.RegisterEnum(%q, %[3]s_name, %[3]s_value)", g.Pkg["proto"], pkg+ccTypeName, ccTypeName)
}

// And now lots of helper functions.

// Is c an ASCII lower-case letter?
func isASCIILower(c byte) bool {
        return 'a' <= c && c <= 'z'
}

// Is c an ASCII digit?
func isASCIIDigit(c byte) bool {
        return '0' <= c && c <= '9'
}

// CamelCase returns the CamelCased name.
// If there is an interior underscore followed by a lower case letter,
// drop the underscore and convert the letter to upper case.
// There is a remote possibility of this rewrite causing a name collision,
// but it's so remote we're prepared to pretend it's nonexistent - since the
// C++ generator lowercases names, it's extremely unlikely to have two fields
// with different capitalizations.
// In short, _my_field_name_2 becomes XMyFieldName_2.
func CamelCase(s string) string {
        if s == "" {
                return ""
        }
        t := make([]byte, 0, 32)
        i := 0
        if s[0] == '_' {
                // Need a capital letter; drop the '_'.
                t = append(t, 'X')
                i++
        }
        // Invariant: if the next letter is lower case, it must be converted
        // to upper case.
        // That is, we process a word at a time, where words are marked by _ or
        // upper case letter. Digits are treated as words.
        for ; i < len(s); i++ {
                c := s[i]
                if c == '_' && i+1 < len(s) && isASCIILower(s[i+1]) {
                        continue // Skip the underscore in s.
                }
                if isASCIIDigit(c) {
                        t = append(t, c)
                        continue
                }
                // Assume we have a letter now - if not, it's a bogus identifier.
                // The next word is a sequence of characters that must start upper case.
                if isASCIILower(c) {
                        c ^= ' ' // Make it a capital letter.
                }
                t = append(t, c) // Guaranteed not lower case.
                // Accept lower case sequence that follows.
                for i+1 < len(s) && isASCIILower(s[i+1]) {
                        i++
                        t = append(t, s[i])
                }
        }
        return string(t)
}

// CamelCaseSlice is like CamelCase, but the argument is a slice of strings to
// be joined with "_".
func CamelCaseSlice(elem []string) string { return CamelCase(strings.Join(elem, "_")) }

// dottedSlice turns a sliced name into a dotted name.
func dottedSlice(elem []string) string { return strings.Join(elem, ".") }

// Is this field optional?
func isOptional(field *descriptor.FieldDescriptorProto) bool {
        return field.Label != nil && *field.Label == descriptor.FieldDescriptorProto_LABEL_OPTIONAL
}

// Is this field required?
func isRequired(field *descriptor.FieldDescriptorProto) bool {
        return field.Label != nil && *field.Label == descriptor.FieldDescriptorProto_LABEL_REQUIRED
}

// Is this field repeated?
func isRepeated(field *descriptor.FieldDescriptorProto) bool {
        return field.Label != nil && *field.Label == descriptor.FieldDescriptorProto_LABEL_REPEATED
}

// Is this field a scalar numeric type?
func isScalar(field *descriptor.FieldDescriptorProto) bool {
        if field.Type == nil {
                return false
        }
        switch *field.Type {
        case descriptor.FieldDescriptorProto_TYPE_DOUBLE,
                descriptor.FieldDescriptorProto_TYPE_FLOAT,
                descriptor.FieldDescriptorProto_TYPE_INT64,
                descriptor.FieldDescriptorProto_TYPE_UINT64,
                descriptor.FieldDescriptorProto_TYPE_INT32,
                descriptor.FieldDescriptorProto_TYPE_FIXED64,
                descriptor.FieldDescriptorProto_TYPE_FIXED32,
                descriptor.FieldDescriptorProto_TYPE_BOOL,
                descriptor.FieldDescriptorProto_TYPE_UINT32,
                descriptor.FieldDescriptorProto_TYPE_ENUM,
                descriptor.FieldDescriptorProto_TYPE_SFIXED32,
                descriptor.FieldDescriptorProto_TYPE_SFIXED64,
                descriptor.FieldDescriptorProto_TYPE_SINT32,
                descriptor.FieldDescriptorProto_TYPE_SINT64:
                return true
        default:
                return false
        }
}

// badToUnderscore is the mapping function used to generate Go names from package names,
// which can be dotted in the input .proto file.  It replaces non-identifier characters such as
// dot or dash with underscore.
func badToUnderscore(r rune) rune {
        if unicode.IsLetter(r) || unicode.IsDigit(r) || r == '_' {
                return r
        }
        return '_'
}

// 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[0:i]
        }
        return name
}

// The SourceCodeInfo message describes the location of elements of a parsed
// .proto file by way of a "path", which is a sequence of integers that
// describe the route from a FileDescriptorProto to the relevant submessage.
// The path alternates between a field number of a repeated field, and an index
// into that repeated field. The constants below define the field numbers that
// are used.
//
// See descriptor.proto for more information about this.
const (
        // tag numbers in FileDescriptorProto
        packagePath = 2 // package
        messagePath = 4 // message_type
        enumPath    = 5 // enum_type
        // tag numbers in DescriptorProto
        messageFieldPath   = 2 // field
        messageMessagePath = 3 // nested_type
        messageEnumPath    = 4 // enum_type
        messageOneofPath   = 8 // oneof_decl
        // tag numbers in EnumDescriptorProto
        enumValuePath = 2 // value
)

var supportTypeAliases bool

func init() {
        for _, tag := range build.Default.ReleaseTags {
                if tag == "go1.9" {
                        supportTypeAliases = true
                        return
                }
        }
}