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[bytom/vapor.git] / 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"
        "fmt"
        "go/parser"
        "go/printer"
        "go/token"
        "log"
        "os"
        "path"
        "strconv"
        "strings"
        "unicode"
        "unicode/utf8"

        "github.com/golang/protobuf/proto"

        "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 = 2

// 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)
}

// 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 *descriptor.FileDescriptorProto // File this object comes from.
}

// PackageName is name in the package clause in the generated file.
func (c *common) PackageName() string { return uniquePackageOf(c.file) }

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

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

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

// 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, 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

        index int // The index of this file in the list of files to generate code for

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

// PackageName is the package name we'll use in the generated code to refer to this file.
func (d *FileDescriptor) PackageName() string { return uniquePackageOf(d.FileDescriptorProto) }

// 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 { return fmt.Sprintf("fileDescriptor%d", d.index) }

// 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, pkg string, ok bool) {
        pkg = d.GetOptions().GetGoPackage()
        if pkg == "" {
                return
        }
        ok = true
        // The presence of a slash implies there's an import path.
        slash := strings.LastIndex(pkg, "/")
        if slash < 0 {
                return
        }
        impPath, pkg = pkg, pkg[slash+1:]
        // A semicolon-delimited suffix overrides the package name.
        sc := strings.IndexByte(impPath, ';')
        if sc < 0 {
                return
        }
        impPath, pkg = impPath[:sc], impPath[sc+1:]
        return
}

// goPackageName returns the Go package name to use in the
// generated Go file.  The result explicit reports whether the name
// came from an option go_package statement.  If explicit is false,
// the name was derived from the protocol buffer's package statement
// or the input file name.
func (d *FileDescriptor) goPackageName() (name string, explicit bool) {
        // Does the file have a "go_package" option?
        if _, pkg, ok := d.goPackageOption(); ok {
                return pkg, true
        }

        // Does the file have a package clause?
        if pkg := d.GetPackage(); pkg != "" {
                return pkg, false
        }
        // Use the file base name.
        return baseName(d.GetName()), false
}

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

        // 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(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, pkg string)
}

type messageSymbol struct {
        sym                         string
        hasExtensions, isMessageSet bool
        hasOneof                    bool
        getters                     []getterSymbol
}

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, pkg string) {
        remoteSym := pkg + "." + ms.sym

        g.P("type ", ms.sym, " ", remoteSym)
        g.P("func (m *", ms.sym, ") Reset() { (*", remoteSym, ")(m).Reset() }")
        g.P("func (m *", ms.sym, ") String() string { return (*", remoteSym, ")(m).String() }")
        g.P("func (*", ms.sym, ") ProtoMessage() {}")
        if ms.hasExtensions {
                g.P("func (*", ms.sym, ") ExtensionRangeArray() []", g.Pkg["proto"], ".ExtensionRange ",
                        "{ return (*", remoteSym, ")(nil).ExtensionRangeArray() }")
                if ms.isMessageSet {
                        g.P("func (m *", ms.sym, ") Marshal() ([]byte, error) ",
                                "{ return (*", remoteSym, ")(m).Marshal() }")
                        g.P("func (m *", ms.sym, ") Unmarshal(buf []byte) error ",
                                "{ return (*", remoteSym, ")(m).Unmarshal(buf) }")
                }
        }
        if ms.hasOneof {
                // Oneofs and public imports do not mix well.
                // We can make them work okay for the binary format,
                // but they're going to break weirdly for text/JSON.
                enc := "_" + ms.sym + "_OneofMarshaler"
                dec := "_" + ms.sym + "_OneofUnmarshaler"
                size := "_" + ms.sym + "_OneofSizer"
                encSig := "(msg " + g.Pkg["proto"] + ".Message, b *" + g.Pkg["proto"] + ".Buffer) error"
                decSig := "(msg " + g.Pkg["proto"] + ".Message, tag, wire int, b *" + g.Pkg["proto"] + ".Buffer) (bool, error)"
                sizeSig := "(msg " + g.Pkg["proto"] + ".Message) int"
                g.P("func (m *", ms.sym, ") XXX_OneofFuncs() (func", encSig, ", func", decSig, ", func", sizeSig, ", []interface{}) {")
                g.P("return ", enc, ", ", dec, ", ", size, ", nil")
                g.P("}")

                g.P("func ", enc, encSig, " {")
                g.P("m := msg.(*", ms.sym, ")")
                g.P("m0 := (*", remoteSym, ")(m)")
                g.P("enc, _, _, _ := m0.XXX_OneofFuncs()")
                g.P("return enc(m0, b)")
                g.P("}")

                g.P("func ", dec, decSig, " {")
                g.P("m := msg.(*", ms.sym, ")")
                g.P("m0 := (*", remoteSym, ")(m)")
                g.P("_, dec, _, _ := m0.XXX_OneofFuncs()")
                g.P("return dec(m0, tag, wire, b)")
                g.P("}")

                g.P("func ", size, sizeSig, " {")
                g.P("m := msg.(*", ms.sym, ")")
                g.P("m0 := (*", remoteSym, ")(m)")
                g.P("_, _, size, _ := m0.XXX_OneofFuncs()")
                g.P("return size(m0)")
                g.P("}")
        }
        for _, get := range ms.getters {

                if get.typeName != "" {
                        g.RecordTypeUse(get.typeName)
                }
                typ := get.typ
                val := "(*" + remoteSym + ")(m)." + get.name + "()"
                if get.genType {
                        // typ will be "*pkg.T" (message/group) or "pkg.T" (enum)
                        // or "map[t]*pkg.T" (map to message/enum).
                        // The first two of those might have a "[]" prefix if it is repeated.
                        // Drop any package qualifier since we have hoisted the type into this package.
                        rep := strings.HasPrefix(typ, "[]")
                        if rep {
                                typ = typ[2:]
                        }
                        isMap := strings.HasPrefix(typ, "map[")
                        star := typ[0] == '*'
                        if !isMap { // map types handled lower down
                                typ = typ[strings.Index(typ, ".")+1:]
                        }
                        if star {
                                typ = "*" + typ
                        }
                        if rep {
                                // Go does not permit conversion between slice types where both
                                // element types are named. That means we need to generate a bit
                                // of code in this situation.
                                // typ is the element type.
                                // val is the expression to get the slice from the imported type.

                                ctyp := typ // conversion type expression; "Foo" or "(*Foo)"
                                if star {
                                        ctyp = "(" + typ + ")"
                                }

                                g.P("func (m *", ms.sym, ") ", get.name, "() []", typ, " {")
                                g.In()
                                g.P("o := ", val)
                                g.P("if o == nil {")
                                g.In()
                                g.P("return nil")
                                g.Out()
                                g.P("}")
                                g.P("s := make([]", typ, ", len(o))")
                                g.P("for i, x := range o {")
                                g.In()
                                g.P("s[i] = ", ctyp, "(x)")
                                g.Out()
                                g.P("}")
                                g.P("return s")
                                g.Out()
                                g.P("}")
                                continue
                        }
                        if isMap {
                                // Split map[keyTyp]valTyp.
                                bra, ket := strings.Index(typ, "["), strings.Index(typ, "]")
                                keyTyp, valTyp := typ[bra+1:ket], typ[ket+1:]
                                // Drop any package qualifier.
                                // Only the value type may be foreign.
                                star := valTyp[0] == '*'
                                valTyp = valTyp[strings.Index(valTyp, ".")+1:]
                                if star {
                                        valTyp = "*" + valTyp
                                }

                                typ := "map[" + keyTyp + "]" + valTyp
                                g.P("func (m *", ms.sym, ") ", get.name, "() ", typ, " {")
                                g.P("o := ", val)
                                g.P("if o == nil { return nil }")
                                g.P("s := make(", typ, ", len(o))")
                                g.P("for k, v := range o {")
                                g.P("s[k] = (", valTyp, ")(v)")
                                g.P("}")
                                g.P("return s")
                                g.P("}")
                                continue
                        }
                        // Convert imported type into the forwarding type.
                        val = "(" + typ + ")(" + val + ")"
                }

                g.P("func (m *", ms.sym, ") ", get.name, "() ", typ, " { return ", val, " }")
        }

}

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

func (es enumSymbol) GenerateAlias(g *Generator, pkg string) {
        s := es.name
        g.P("type ", s, " ", pkg, ".", s)
        g.P("var ", s, "_name = ", pkg, ".", s, "_name")
        g.P("var ", s, "_value = ", pkg, ".", s, "_value")
        g.P("func (x ", s, ") String() string { return (", pkg, ".", s, ")(x).String() }")
        if !es.proto3 {
                g.P("func (x ", s, ") Enum() *", s, "{ return (*", s, ")((", pkg, ".", s, ")(x).Enum()) }")
                g.P("func (x *", s, ") UnmarshalJSON(data []byte) error { return (*", pkg, ".", s, ")(x).UnmarshalJSON(data) }")
        }
}

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, pkg string) {
        v := 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 {
        PackageName() string // The name we use in our output (a_b_c), possibly renamed for uniqueness.
        TypeName() []string
        File() *descriptor.FileDescriptorProto
}

// Each package name we generate must be unique. The package we're generating
// gets its own name but every other package must have a unique name that does
// not conflict in the code we generate.  These names are chosen globally (although
// they don't have to be, it simplifies things to do them globally).
func uniquePackageOf(fd *descriptor.FileDescriptorProto) string {
        s, ok := uniquePackageName[fd]
        if !ok {
                log.Fatal("internal error: no package name defined for " + fd.GetName())
        }
        return s
}

// 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

        packageName      string                     // What we're calling ourselves.
        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.
        usedPackages     map[string]bool            // Names of packages used in current file.
        typeNameToObject map[string]Object          // Key is a fully-qualified name in input syntax.
        init             []string                   // Lines to emit in the init function.
        indent           string
        writeOutput      bool
}

// 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 "plugins":
                        pluginList = v
                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 {
        pkg := obj.PackageName()
        if pkg == g.packageName {
                return ""
        }
        return pkg + "."
}

// For each input file, the unique package name to use, underscored.
var uniquePackageName = make(map[*descriptor.FileDescriptorProto]string)

// Package names already registered.  Key is the name from the .proto file;
// value is the name that appears in the generated code.
var pkgNamesInUse = make(map[string]bool)

// Create and remember a guaranteed unique package name for this file descriptor.
// Pkg is the candidate name.  If f is nil, it's a builtin package like "proto" and
// has no file descriptor.
func RegisterUniquePackageName(pkg string, f *FileDescriptor) string {
        // Convert dots to underscores before finding a unique alias.
        pkg = strings.Map(badToUnderscore, pkg)

        for i, orig := 1, pkg; pkgNamesInUse[pkg]; i++ {
                // It's a duplicate; must rename.
                pkg = orig + strconv.Itoa(i)
        }
        // Install it.
        pkgNamesInUse[pkg] = true
        if f != nil {
                uniquePackageName[f.FileDescriptorProto] = pkg
        }
        return pkg
}

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,
}

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

        p = strings.Map(badToUnderscore, p)
        // Identifier must not be keyword: insert _.
        if isGoKeyword[p] {
                p = "_" + p
        }
        // Identifier must not begin with digit: insert _.
        if r, _ := utf8.DecodeRuneInString(p); unicode.IsDigit(r) {
                p = "_" + p
        }
        return 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() {
        // Register the name for this package.  It will be the first name
        // registered so is guaranteed to be unmodified.
        pkg, explicit := g.genFiles[0].goPackageName()

        // Check all files for an explicit go_package option.
        for _, f := range g.genFiles {
                thisPkg, thisExplicit := f.goPackageName()
                if thisExplicit {
                        if !explicit {
                                // Let this file's go_package option serve for all input files.
                                pkg, explicit = thisPkg, true
                        } else if thisPkg != pkg {
                                g.Fail("inconsistent package names:", thisPkg, pkg)
                        }
                }
        }

        // If we don't have an explicit go_package option but we have an
        // import path, use that.
        if !explicit {
                p := g.defaultGoPackage()
                if p != "" {
                        pkg, explicit = p, true
                }
        }

        // If there was no go_package and no import path to use,
        // double-check that all the inputs have the same implicit
        // Go package name.
        if !explicit {
                for _, f := range g.genFiles {
                        thisPkg, _ := f.goPackageName()
                        if thisPkg != pkg {
                                g.Fail("inconsistent package names:", thisPkg, pkg)
                        }
                }
        }

        g.packageName = RegisterUniquePackageName(pkg, g.genFiles[0])

        // Register the support package names. They might collide with the
        // name of a package we import.
        g.Pkg = map[string]string{
                "fmt":   RegisterUniquePackageName("fmt", nil),
                "math":  RegisterUniquePackageName("math", nil),
                "proto": RegisterUniquePackageName("proto", nil),
        }

AllFiles:
        for _, f := range g.allFiles {
                for _, genf := range g.genFiles {
                        if f == genf {
                                // In this package already.
                                uniquePackageName[f.FileDescriptorProto] = g.packageName
                                continue AllFiles
                        }
                }
                // The file is a dependency, so we want to ignore its go_package option
                // because that is only relevant for its specific generated output.
                pkg := f.GetPackage()
                if pkg == "" {
                        pkg = baseName(*f.Name)
                }
                RegisterUniquePackageName(pkg, f)
        }
}

// 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))
        for _, f := range g.Request.ProtoFile {
                // We must wrap the descriptors before we wrap the enums
                descs := wrapDescriptors(f)
                g.buildNestedDescriptors(descs)
                enums := wrapEnumDescriptors(f, descs)
                g.buildNestedEnums(descs, enums)
                exts := wrapExtensions(f)
                fd := &FileDescriptor{
                        FileDescriptorProto: f,
                        desc:                descs,
                        enum:                enums,
                        ext:                 exts,
                        exported:            make(map[Object][]symbol),
                        proto3:              fileIsProto3(f),
                }
                extractComments(fd)
                g.allFiles = append(g.allFiles, fd)
                g.allFilesByName[f.GetName()] = fd
        }
        for _, fd := range g.allFiles {
                fd.imp = wrapImported(fd.FileDescriptorProto, 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)
                }
                fd.index = len(g.genFiles)
                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 *descriptor.FileDescriptorProto, 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 *descriptor.FileDescriptorProto) []*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 *descriptor.FileDescriptorProto, 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 *descriptor.FileDescriptorProto, 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 *descriptor.FileDescriptorProto, 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 *descriptor.FileDescriptorProto) []*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 *descriptor.FileDescriptorProto, 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)
        }

        // If the file of this object isn't a direct dependency of the current file,
        // or in the current file, then this object has been publicly imported into
        // a dependency of the current file.
        // We should return the ImportedDescriptor object for it instead.
        direct := *o.File().Name == *g.file.Name
        if !direct {
                for _, dep := range g.file.Dependency {
                        if *g.fileByName(dep).Name == *o.File().Name {
                                direct = true
                                break
                        }
                }
        }
        if !direct {
                found := false
        Loop:
                for _, dep := range g.file.Dependency {
                        df := g.fileByName(*g.fileByName(dep).Name)
                        for _, td := range df.imp {
                                if td.o == o {
                                        // Found it!
                                        o = td
                                        found = true
                                        break Loop
                                }
                        }
                }
                if !found {
                        log.Printf("protoc-gen-go: WARNING: failed finding publicly imported dependency for %v, used in %v", typeName, *g.file.Name)
                }
        }

        return o
}

// P prints the arguments to the generated output.  It handles strings and int32s, plus
// handling indirections because they may be *string, etc.
func (g *Generator) P(str ...interface{}) {
        if !g.writeOutput {
                return
        }
        g.WriteString(g.indent)
        for _, v := range str {
                switch s := v.(type) {
                case string:
                        g.WriteString(s)
                case *string:
                        g.WriteString(*s)
                case bool:
                        fmt.Fprintf(g, "%t", s)
                case *bool:
                        fmt.Fprintf(g, "%t", *s)
                case int:
                        fmt.Fprintf(g, "%d", s)
                case *int32:
                        fmt.Fprintf(g, "%d", *s)
                case *int64:
                        fmt.Fprintf(g, "%d", *s)
                case float64:
                        fmt.Fprintf(g, "%g", s)
                case *float64:
                        fmt.Fprintf(g, "%g", *s)
                default:
                        g.Fail(fmt.Sprintf("unknown type in printer: %T", 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.writeOutput = genFileMap[file]
                g.generate(file)
                if !g.writeOutput {
                        continue
                }
                g.Response.File = append(g.Response.File, &plugin.CodeGeneratorResponse_File{
                        Name:    proto.String(file.goFileName()),
                        Content: proto.String(g.String()),
                })
        }
}

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

// FileOf return the FileDescriptor for this FileDescriptorProto.
func (g *Generator) FileOf(fd *descriptor.FileDescriptorProto) *FileDescriptor {
        for _, file := range g.allFiles {
                if file.FileDescriptorProto == fd {
                        return file
                }
        }
        g.Fail("could not find file in table:", fd.GetName())
        return nil
}

// 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 = g.FileOf(file.FileDescriptorProto)
        g.usedPackages = make(map[string]bool)

        if g.file.index == 0 {
                // For one file in the package, assert version compatibility.
                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()

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

        g.generateFileDescriptor(file)

        // Generate header and imports last, though they appear first in the output.
        rem := g.Buffer
        g.Buffer = new(bytes.Buffer)
        g.generateHeader()
        g.generateImports()
        if !g.writeOutput {
                return
        }
        g.Write(rem.Bytes())

        // Reformat generated code.
        fset := token.NewFileSet()
        raw := g.Bytes()
        ast, err := parser.ParseFile(fset, "", g, 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(raw))
                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())
        }
        g.Reset()
        err = (&printer.Config{Mode: printer.TabIndent | printer.UseSpaces, Tabwidth: 8}).Fprint(g, fset, ast)
        if err != nil {
                g.Fail("generated Go source code could not be reformatted:", err.Error())
        }
}

// Generate the header, including package definition
func (g *Generator) generateHeader() {
        g.P("// Code generated by protoc-gen-go. DO NOT EDIT.")
        g.P("// source: ", g.file.Name)
        g.P()

        name := g.file.PackageName()

        if g.file.index == 0 {
                // Generate package docs for the first file in the package.
                g.P("/*")
                g.P("Package ", name, " is a generated protocol buffer package.")
                g.P()
                if loc, ok := g.file.comments[strconv.Itoa(packagePath)]; ok {
                        // not using g.PrintComments because this is a /* */ comment block.
                        text := strings.TrimSuffix(loc.GetLeadingComments(), "\n")
                        for _, line := range strings.Split(text, "\n") {
                                line = strings.TrimPrefix(line, " ")
                                // ensure we don't escape from the block comment
                                line = strings.Replace(line, "*/", "* /", -1)
                                g.P(line)
                        }
                        g.P()
                }
                var topMsgs []string
                g.P("It is generated from these files:")
                for _, f := range g.genFiles {
                        g.P("\t", f.Name)
                        for _, msg := range f.desc {
                                if msg.parent != nil {
                                        continue
                                }
                                topMsgs = append(topMsgs, CamelCaseSlice(msg.TypeName()))
                        }
                }
                g.P()
                g.P("It has these top-level messages:")
                for _, msg := range topMsgs {
                        g.P("\t", msg)
                }
                g.P("*/")
        }

        g.P("package ", name)
        g.P()
}

// 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 loc, ok := g.file.comments[path]; ok {
                text := strings.TrimSuffix(loc.GetLeadingComments(), "\n")
                for _, line := range strings.Split(text, "\n") {
                        g.P("// ", strings.TrimPrefix(line, " "))
                }
                return true
        }
        return false
}

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() {
        // 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.Pkg["proto"] + " " + strconv.Quote(g.ImportPrefix+"github.com/golang/protobuf/proto"))
        g.P("import " + g.Pkg["fmt"] + ` "fmt"`)
        g.P("import " + g.Pkg["math"] + ` "math"`)
        for i, s := range g.file.Dependency {
                fd := g.fileByName(s)
                // Do not import our own package.
                if fd.PackageName() == g.packageName {
                        continue
                }
                filename := fd.goFileName()
                // By default, import path is the dirname of the Go filename.
                importPath := path.Dir(filename)
                if substitution, ok := g.ImportMap[s]; ok {
                        importPath = substitution
                }
                importPath = g.ImportPrefix + importPath
                // Skip weak imports.
                if g.weak(int32(i)) {
                        g.P("// skipping weak import ", fd.PackageName(), " ", strconv.Quote(importPath))
                        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.
                pname := fd.PackageName()
                if _, ok := g.usedPackages[pname]; !ok {
                        pname = "_"
                }
                g.P("import ", pname, " ", strconv.Quote(importPath))
        }
        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) {
        // Don't generate public import symbols for files that we are generating
        // code for, since those symbols will already be in this package.
        // We can't simply avoid creating the ImportedDescriptor objects,
        // because g.genFiles isn't populated at that stage.
        tn := id.TypeName()
        sn := tn[len(tn)-1]
        df := g.FileOf(id.o.File())
        filename := *df.Name
        for _, fd := range g.genFiles {
                if *fd.Name == filename {
                        g.P("// Ignoring public import of ", sn, " from ", filename)
                        g.P()
                        return
                }
        }
        g.P("// ", sn, " from public import ", filename)
        g.usedPackages[df.PackageName()] = true

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

        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()

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

                name := ccPrefix + *e.Name
                g.P(name, " ", ccTypeName, " = ", e.Number)
                g.file.addExport(enum, constOrVarSymbol{name, "const", ccTypeName})
        }
        g.Out()
        g.P(")")
        g.P("var ", ccTypeName, "_name = map[int32]string{")
        g.In()
        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.Out()
        g.P("}")
        g.P("var ", ccTypeName, "_value = map[string]int32{")
        g.In()
        for _, e := range enum.Value {
                g.P(strconv.Quote(*e.Name), ": ", e.Number, ",")
        }
        g.Out()
        g.P("}")

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

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

        if !enum.proto3() {
                g.P("func (x *", ccTypeName, ") UnmarshalJSON(data []byte) error {")
                g.In()
                g.P("value, err := ", g.Pkg["proto"], ".UnmarshalJSONEnum(", ccTypeName, `_value, data, "`, ccTypeName, `")`)
                g.P("if err != nil {")
                g.In()
                g.P("return err")
                g.Out()
                g.P("}")
                g.P("*x = ", ccTypeName, "(value)")
                g.P("return nil")
                g.Out()
                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) { return ", g.file.VarName(), ", []int{", strings.Join(indexes, ", "), "} }")
        if enum.file.GetPackage() == "google.protobuf" && enum.GetName() == "NullValue" {
                g.P("func (", ccTypeName, `) XXX_WellKnownType() string { return "`, enum.GetName(), `" }`)
        }

        g.P()
}

// 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)
                }
                defaultValue = ",def=" + defaultValue
        }
        enum := ""
        if *field.Type == descriptor.FieldDescriptorProto_TYPE_ENUM {
                // We avoid using obj.PackageName(), 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(); 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() {
                // We only need the extra tag for []byte fields;
                // no need to add noise for the others.
                if *field.Type == descriptor.FieldDescriptorProto_TYPE_BYTES {
                        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())
}

// TypeNameWithPackage is like TypeName, but always includes the package
// name even if the object is in our own package.
func (g *Generator) TypeNameWithPackage(obj Object) string {
        return obj.PackageName() + 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 obj, ok := g.typeNameToObject[t]; ok {
                // Call ObjectNamed to get the true object to record the use.
                obj = g.ObjectNamed(t)
                g.usedPackages[obj.PackageName()] = 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,
}

// Generate the type and default constant definitions for this Descriptor.
func (g *Generator) generateMessage(message *Descriptor) {
        // The full type name
        typeName := message.TypeName()
        // The full type name, CamelCased.
        ccTypeName := CamelCaseSlice(typeName)

        usedNames := make(map[string]bool)
        for _, n := range methodNames {
                usedNames[n] = true
        }
        fieldNames := make(map[*descriptor.FieldDescriptorProto]string)
        fieldGetterNames := make(map[*descriptor.FieldDescriptorProto]string)
        fieldTypes := make(map[*descriptor.FieldDescriptorProto]string)
        mapFieldTypes := make(map[*descriptor.FieldDescriptorProto]string)

        oneofFieldName := make(map[int32]string)                           // indexed by oneof_index field of FieldDescriptorProto
        oneofDisc := make(map[int32]string)                                // name of discriminator method
        oneofTypeName := make(map[*descriptor.FieldDescriptorProto]string) // without star
        oneofInsertPoints := make(map[int32]int)                           // oneof_index => offset of g.Buffer

        g.PrintComments(message.path)
        g.P("type ", ccTypeName, " struct {")
        g.In()

        // 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
                }
        }

        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")

                fieldNames[field] = fieldName
                fieldGetterNames[field] = fieldGetterName

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

                        // This is the first field of a oneof we haven't seen before.
                        // Generate the union field.
                        com := g.PrintComments(fmt.Sprintf("%s,%d,%d", message.path, messageOneofPath, *field.OneofIndex))
                        if com {
                                g.P("//")
                        }
                        g.P("// Types that are valid to be assigned to ", fname, ":")
                        // Generate the rest of this comment later,
                        // when we've computed any disambiguation.
                        oneofInsertPoints[*field.OneofIndex] = g.Buffer.Len()

                        dname := "is" + ccTypeName + "_" + fname
                        oneofFieldName[*field.OneofIndex] = fname
                        oneofDisc[*field.OneofIndex] = dname
                        tag := `protobuf_oneof:"` + odp.GetName() + `"`
                        g.P(fname, " ", dname, " `", tag, "`")
                }

                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)
                        }
                }

                fieldTypes[field] = typename

                if oneof {
                        tname := ccTypeName + "_" + 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
                        }

                        oneofTypeName[field] = tname
                        continue
                }

                g.PrintComments(fmt.Sprintf("%s,%d,%d", message.path, messageFieldPath, i))
                g.P(fieldName, "\t", typename, "\t`", tag, "`")
                g.RecordTypeUse(field.GetTypeName())
        }
        if len(message.ExtensionRange) > 0 {
                g.P(g.Pkg["proto"], ".XXX_InternalExtensions `json:\"-\"`")
        }
        if !message.proto3() {
                g.P("XXX_unrecognized\t[]byte `json:\"-\"`")
        }
        g.Out()
        g.P("}")

        // Update g.Buffer to list valid oneof types.
        // We do this down here, after we've disambiguated the oneof type names.
        // We go in reverse order of insertion point to avoid invalidating offsets.
        for oi := int32(len(message.OneofDecl)); oi >= 0; oi-- {
                ip := oneofInsertPoints[oi]
                all := g.Buffer.Bytes()
                rem := all[ip:]
                g.Buffer = bytes.NewBuffer(all[:ip:ip]) // set cap so we don't scribble on rem
                for _, field := range message.Field {
                        if field.OneofIndex == nil || *field.OneofIndex != oi {
                                continue
                        }
                        g.P("//\t*", oneofTypeName[field])
                }
                g.Buffer.Write(rem)
        }

        // Reset, String and ProtoMessage methods.
        g.P("func (m *", ccTypeName, ") Reset() { *m = ", ccTypeName, "{} }")
        g.P("func (m *", ccTypeName, ") String() string { return ", g.Pkg["proto"], ".CompactTextString(m) }")
        g.P("func (*", ccTypeName, ") ProtoMessage() {}")
        var indexes []string
        for m := message; m != nil; m = m.parent {
                indexes = append([]string{strconv.Itoa(m.index)}, indexes...)
        }
        g.P("func (*", ccTypeName, ") Descriptor() ([]byte, []int) { return ", g.file.VarName(), ", []int{", strings.Join(indexes, ", "), "} }")
        // TODO: Revisit the decision to use a XXX_WellKnownType method
        // if we change proto.MessageName to work with multiple equivalents.
        if message.file.GetPackage() == "google.protobuf" && wellKnownTypes[message.GetName()] {
                g.P("func (*", ccTypeName, `) XXX_WellKnownType() string { return "`, message.GetName(), `" }`)
        }

        // Extension support methods
        var hasExtensions, isMessageSet bool
        if len(message.ExtensionRange) > 0 {
                hasExtensions = true
                // message_set_wire_format only makes sense when extensions are defined.
                if opts := message.Options; opts != nil && opts.GetMessageSetWireFormat() {
                        isMessageSet = true
                        g.P()
                        g.P("func (m *", ccTypeName, ") Marshal() ([]byte, error) {")
                        g.In()
                        g.P("return ", g.Pkg["proto"], ".MarshalMessageSet(&m.XXX_InternalExtensions)")
                        g.Out()
                        g.P("}")
                        g.P("func (m *", ccTypeName, ") Unmarshal(buf []byte) error {")
                        g.In()
                        g.P("return ", g.Pkg["proto"], ".UnmarshalMessageSet(buf, &m.XXX_InternalExtensions)")
                        g.Out()
                        g.P("}")
                        g.P("func (m *", ccTypeName, ") MarshalJSON() ([]byte, error) {")
                        g.In()
                        g.P("return ", g.Pkg["proto"], ".MarshalMessageSetJSON(&m.XXX_InternalExtensions)")
                        g.Out()
                        g.P("}")
                        g.P("func (m *", ccTypeName, ") UnmarshalJSON(buf []byte) error {")
                        g.In()
                        g.P("return ", g.Pkg["proto"], ".UnmarshalMessageSetJSON(buf, &m.XXX_InternalExtensions)")
                        g.Out()
                        g.P("}")
                        g.P("// ensure ", ccTypeName, " satisfies proto.Marshaler and proto.Unmarshaler")
                        g.P("var _ ", g.Pkg["proto"], ".Marshaler = (*", ccTypeName, ")(nil)")
                        g.P("var _ ", g.Pkg["proto"], ".Unmarshaler = (*", ccTypeName, ")(nil)")
                }

                g.P()
                g.P("var extRange_", ccTypeName, " = []", g.Pkg["proto"], ".ExtensionRange{")
                g.In()
                for _, r := range message.ExtensionRange {
                        end := fmt.Sprint(*r.End - 1) // make range inclusive on both ends
                        g.P("{", r.Start, ", ", end, "},")
                }
                g.Out()
                g.P("}")
                g.P("func (*", ccTypeName, ") ExtensionRangeArray() []", g.Pkg["proto"], ".ExtensionRange {")
                g.In()
                g.P("return extRange_", ccTypeName)
                g.Out()
                g.P("}")
        }

        // Default constants
        defNames := make(map[*descriptor.FieldDescriptorProto]string)
        for _, field := range message.Field {
                def := field.GetDefaultValue()
                if def == "" {
                        continue
                }
                fieldname := "Default_" + ccTypeName + "_" + CamelCase(*field.Name)
                defNames[field] = fieldname
                typename, _ := g.GoType(message, field)
                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 *field.Type == descriptor.FieldDescriptorProto_TYPE_FLOAT {
                                def = "float32(" + def + ")"
                        }
                        kind = "var "
                case *field.Type == descriptor.FieldDescriptorProto_TYPE_ENUM:
                        // Must be an enum.  Need to construct the prefixed name.
                        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 constant for %s", fieldname)
                                continue
                        }
                        def = g.DefaultPackageName(obj) + enum.prefix() + def
                }
                g.P(kind, fieldname, " ", typename, " = ", def)
                g.file.addExport(message, constOrVarSymbol{fieldname, kind, ""})
        }
        g.P()

        // Oneof per-field types, discriminants and getters.
        //
        // Generate unexported named types for the discriminant interfaces.
        // We shouldn't have to do this, but there was (~19 Aug 2015) a compiler/linker bug
        // that was triggered by using anonymous interfaces here.
        // TODO: Revisit this and consider reverting back to anonymous interfaces.
        for oi := range message.OneofDecl {
                dname := oneofDisc[int32(oi)]
                g.P("type ", dname, " interface { ", dname, "() }")
        }
        g.P()
        for _, field := range message.Field {
                if field.OneofIndex == nil {
                        continue
                }
                _, wiretype := g.GoType(message, field)
                tag := "protobuf:" + g.goTag(message, field, wiretype)
                g.P("type ", oneofTypeName[field], " struct{ ", fieldNames[field], " ", fieldTypes[field], " `", tag, "` }")
                g.RecordTypeUse(field.GetTypeName())
        }
        g.P()
        for _, field := range message.Field {
                if field.OneofIndex == nil {
                        continue
                }
                g.P("func (*", oneofTypeName[field], ") ", oneofDisc[*field.OneofIndex], "() {}")
        }
        g.P()
        for oi := range message.OneofDecl {
                fname := oneofFieldName[int32(oi)]
                g.P("func (m *", ccTypeName, ") Get", fname, "() ", oneofDisc[int32(oi)], " {")
                g.P("if m != nil { return m.", fname, " }")
                g.P("return nil")
                g.P("}")
        }
        g.P()

        // Field getters
        var getters []getterSymbol
        for _, field := range message.Field {
                oneof := field.OneofIndex != nil

                fname := fieldNames[field]
                typename, _ := g.GoType(message, field)
                if t, ok := mapFieldTypes[field]; ok {
                        typename = t
                }
                mname := fieldGetterNames[field]
                star := ""
                if needsStar(*field.Type) && typename[0] == '*' {
                        typename = typename[1:]
                        star = "*"
                }

                // Only export getter symbols for basic types,
                // and for messages and enums in the same package.
                // Groups are not exported.
                // Foreign types can't be hoisted through a public import because
                // the importer may not already be importing the defining .proto.
                // As an example, imagine we have an import tree like this:
                //   A.proto -> B.proto -> C.proto
                // If A publicly imports B, we need to generate the getters from B in A's output,
                // but if one such getter returns something from C then we cannot do that
                // because A is not importing C already.
                var getter, genType bool
                switch *field.Type {
                case descriptor.FieldDescriptorProto_TYPE_GROUP:
                        getter = false
                case descriptor.FieldDescriptorProto_TYPE_MESSAGE, descriptor.FieldDescriptorProto_TYPE_ENUM:
                        // Only export getter if its return type is in this package.
                        getter = g.ObjectNamed(field.GetTypeName()).PackageName() == message.PackageName()
                        genType = true
                default:
                        getter = true
                }
                if getter {
                        getters = append(getters, getterSymbol{
                                name:     mname,
                                typ:      typename,
                                typeName: field.GetTypeName(),
                                genType:  genType,
                        })
                }

                g.P("func (m *", ccTypeName, ") "+mname+"() "+typename+" {")
                g.In()
                def, hasDef := defNames[field]
                typeDefaultIsNil := false // whether this field type's default value is a literal nil unless specified
                switch *field.Type {
                case descriptor.FieldDescriptorProto_TYPE_BYTES:
                        typeDefaultIsNil = !hasDef
                case descriptor.FieldDescriptorProto_TYPE_GROUP, descriptor.FieldDescriptorProto_TYPE_MESSAGE:
                        typeDefaultIsNil = true
                }
                if isRepeated(field) {
                        typeDefaultIsNil = true
                }
                if typeDefaultIsNil && !oneof {
                        // A bytes field with no explicit default needs less generated code,
                        // as does a message or group field, or a repeated field.
                        g.P("if m != nil {")
                        g.In()
                        g.P("return m." + fname)
                        g.Out()
                        g.P("}")
                        g.P("return nil")
                        g.Out()
                        g.P("}")
                        g.P()
                        continue
                }
                if !oneof {
                        if message.proto3() {
                                g.P("if m != nil {")
                        } else {
                                g.P("if m != nil && m." + fname + " != nil {")
                        }
                        g.In()
                        g.P("return " + star + "m." + fname)
                        g.Out()
                        g.P("}")
                } else {
                        uname := oneofFieldName[*field.OneofIndex]
                        tname := oneofTypeName[field]
                        g.P("if x, ok := m.Get", uname, "().(*", tname, "); ok {")
                        g.P("return x.", fname)
                        g.P("}")
                }
                if hasDef {
                        if *field.Type != descriptor.FieldDescriptorProto_TYPE_BYTES {
                                g.P("return " + def)
                        } else {
                                // The default is a []byte var.
                                // Make a copy when returning it to be safe.
                                g.P("return append([]byte(nil), ", def, "...)")
                        }
                } else {
                        switch *field.Type {
                        case descriptor.FieldDescriptorProto_TYPE_BOOL:
                                g.P("return false")
                        case descriptor.FieldDescriptorProto_TYPE_STRING:
                                g.P(`return ""`)
                        case descriptor.FieldDescriptorProto_TYPE_GROUP,
                                descriptor.FieldDescriptorProto_TYPE_MESSAGE,
                                descriptor.FieldDescriptorProto_TYPE_BYTES:
                                // This is only possible for oneof fields.
                                g.P("return nil")
                        case descriptor.FieldDescriptorProto_TYPE_ENUM:
                                // The default default for an enum is the first value in the enum,
                                // not zero.
                                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())
                                        continue
                                }
                                if len(enum.Value) == 0 {
                                        g.P("return 0 // empty enum")
                                } else {
                                        first := enum.Value[0].GetName()
                                        g.P("return ", g.DefaultPackageName(obj)+enum.prefix()+first)
                                }
                        default:
                                g.P("return 0")
                        }
                }
                g.Out()
                g.P("}")
                g.P()
        }

        if !message.group {
                ms := &messageSymbol{
                        sym:           ccTypeName,
                        hasExtensions: hasExtensions,
                        isMessageSet:  isMessageSet,
                        hasOneof:      len(message.OneofDecl) > 0,
                        getters:       getters,
                }
                g.file.addExport(message, ms)
        }

        // Oneof functions
        if len(message.OneofDecl) > 0 {
                fieldWire := make(map[*descriptor.FieldDescriptorProto]string)

                // method
                enc := "_" + ccTypeName + "_OneofMarshaler"
                dec := "_" + ccTypeName + "_OneofUnmarshaler"
                size := "_" + ccTypeName + "_OneofSizer"
                encSig := "(msg " + g.Pkg["proto"] + ".Message, b *" + g.Pkg["proto"] + ".Buffer) error"
                decSig := "(msg " + g.Pkg["proto"] + ".Message, tag, wire int, b *" + g.Pkg["proto"] + ".Buffer) (bool, error)"
                sizeSig := "(msg " + g.Pkg["proto"] + ".Message) (n int)"

                g.P("// XXX_OneofFuncs is for the internal use of the proto package.")
                g.P("func (*", ccTypeName, ") XXX_OneofFuncs() (func", encSig, ", func", decSig, ", func", sizeSig, ", []interface{}) {")
                g.P("return ", enc, ", ", dec, ", ", size, ", []interface{}{")
                for _, field := range message.Field {
                        if field.OneofIndex == nil {
                                continue
                        }
                        g.P("(*", oneofTypeName[field], ")(nil),")
                }
                g.P("}")
                g.P("}")
                g.P()

                // marshaler
                g.P("func ", enc, encSig, " {")
                g.P("m := msg.(*", ccTypeName, ")")
                for oi, odp := range message.OneofDecl {
                        g.P("// ", odp.GetName())
                        fname := oneofFieldName[int32(oi)]
                        g.P("switch x := m.", fname, ".(type) {")
                        for _, field := range message.Field {
                                if field.OneofIndex == nil || int(*field.OneofIndex) != oi {
                                        continue
                                }
                                g.P("case *", oneofTypeName[field], ":")
                                var wire, pre, post string
                                val := "x." + fieldNames[field] // overridden for TYPE_BOOL
                                canFail := false                // only TYPE_MESSAGE and TYPE_GROUP can fail
                                switch *field.Type {
                                case descriptor.FieldDescriptorProto_TYPE_DOUBLE:
                                        wire = "WireFixed64"
                                        pre = "b.EncodeFixed64(" + g.Pkg["math"] + ".Float64bits("
                                        post = "))"
                                case descriptor.FieldDescriptorProto_TYPE_FLOAT:
                                        wire = "WireFixed32"
                                        pre = "b.EncodeFixed32(uint64(" + g.Pkg["math"] + ".Float32bits("
                                        post = ")))"
                                case descriptor.FieldDescriptorProto_TYPE_INT64,
                                        descriptor.FieldDescriptorProto_TYPE_UINT64:
                                        wire = "WireVarint"
                                        pre, post = "b.EncodeVarint(uint64(", "))"
                                case descriptor.FieldDescriptorProto_TYPE_INT32,
                                        descriptor.FieldDescriptorProto_TYPE_UINT32,
                                        descriptor.FieldDescriptorProto_TYPE_ENUM:
                                        wire = "WireVarint"
                                        pre, post = "b.EncodeVarint(uint64(", "))"
                                case descriptor.FieldDescriptorProto_TYPE_FIXED64,
                                        descriptor.FieldDescriptorProto_TYPE_SFIXED64:
                                        wire = "WireFixed64"
                                        pre, post = "b.EncodeFixed64(uint64(", "))"
                                case descriptor.FieldDescriptorProto_TYPE_FIXED32,
                                        descriptor.FieldDescriptorProto_TYPE_SFIXED32:
                                        wire = "WireFixed32"
                                        pre, post = "b.EncodeFixed32(uint64(", "))"
                                case descriptor.FieldDescriptorProto_TYPE_BOOL:
                                        // bool needs special handling.
                                        g.P("t := uint64(0)")
                                        g.P("if ", val, " { t = 1 }")
                                        val = "t"
                                        wire = "WireVarint"
                                        pre, post = "b.EncodeVarint(", ")"
                                case descriptor.FieldDescriptorProto_TYPE_STRING:
                                        wire = "WireBytes"
                                        pre, post = "b.EncodeStringBytes(", ")"
                                case descriptor.FieldDescriptorProto_TYPE_GROUP:
                                        wire = "WireStartGroup"
                                        pre, post = "b.Marshal(", ")"
                                        canFail = true
                                case descriptor.FieldDescriptorProto_TYPE_MESSAGE:
                                        wire = "WireBytes"
                                        pre, post = "b.EncodeMessage(", ")"
                                        canFail = true
                                case descriptor.FieldDescriptorProto_TYPE_BYTES:
                                        wire = "WireBytes"
                                        pre, post = "b.EncodeRawBytes(", ")"
                                case descriptor.FieldDescriptorProto_TYPE_SINT32:
                                        wire = "WireVarint"
                                        pre, post = "b.EncodeZigzag32(uint64(", "))"
                                case descriptor.FieldDescriptorProto_TYPE_SINT64:
                                        wire = "WireVarint"
                                        pre, post = "b.EncodeZigzag64(uint64(", "))"
                                default:
                                        g.Fail("unhandled oneof field type ", field.Type.String())
                                }
                                fieldWire[field] = wire
                                g.P("b.EncodeVarint(", field.Number, "<<3|", g.Pkg["proto"], ".", wire, ")")
                                if !canFail {
                                        g.P(pre, val, post)
                                } else {
                                        g.P("if err := ", pre, val, post, "; err != nil {")
                                        g.P("return err")
                                        g.P("}")
                                }
                                if *field.Type == descriptor.FieldDescriptorProto_TYPE_GROUP {
                                        g.P("b.EncodeVarint(", field.Number, "<<3|", g.Pkg["proto"], ".WireEndGroup)")
                                }
                        }
                        g.P("case nil:")
                        g.P("default: return ", g.Pkg["fmt"], `.Errorf("`, ccTypeName, ".", fname, ` has unexpected type %T", x)`)
                        g.P("}")
                }
                g.P("return nil")
                g.P("}")
                g.P()

                // unmarshaler
                g.P("func ", dec, decSig, " {")
                g.P("m := msg.(*", ccTypeName, ")")
                g.P("switch tag {")
                for _, field := range message.Field {
                        if field.OneofIndex == nil {
                                continue
                        }
                        odp := message.OneofDecl[int(*field.OneofIndex)]
                        g.P("case ", field.Number, ": // ", odp.GetName(), ".", *field.Name)
                        g.P("if wire != ", g.Pkg["proto"], ".", fieldWire[field], " {")
                        g.P("return true, ", g.Pkg["proto"], ".ErrInternalBadWireType")
                        g.P("}")
                        lhs := "x, err" // overridden for TYPE_MESSAGE and TYPE_GROUP
                        var dec, cast, cast2 string
                        switch *field.Type {
                        case descriptor.FieldDescriptorProto_TYPE_DOUBLE:
                                dec, cast = "b.DecodeFixed64()", g.Pkg["math"]+".Float64frombits"
                        case descriptor.FieldDescriptorProto_TYPE_FLOAT:
                                dec, cast, cast2 = "b.DecodeFixed32()", "uint32", g.Pkg["math"]+".Float32frombits"
                        case descriptor.FieldDescriptorProto_TYPE_INT64:
                                dec, cast = "b.DecodeVarint()", "int64"
                        case descriptor.FieldDescriptorProto_TYPE_UINT64:
                                dec = "b.DecodeVarint()"
                        case descriptor.FieldDescriptorProto_TYPE_INT32:
                                dec, cast = "b.DecodeVarint()", "int32"
                        case descriptor.FieldDescriptorProto_TYPE_FIXED64:
                                dec = "b.DecodeFixed64()"
                        case descriptor.FieldDescriptorProto_TYPE_FIXED32:
                                dec, cast = "b.DecodeFixed32()", "uint32"
                        case descriptor.FieldDescriptorProto_TYPE_BOOL:
                                dec = "b.DecodeVarint()"
                                // handled specially below
                        case descriptor.FieldDescriptorProto_TYPE_STRING:
                                dec = "b.DecodeStringBytes()"
                        case descriptor.FieldDescriptorProto_TYPE_GROUP:
                                g.P("msg := new(", fieldTypes[field][1:], ")") // drop star
                                lhs = "err"
                                dec = "b.DecodeGroup(msg)"
                                // handled specially below
                        case descriptor.FieldDescriptorProto_TYPE_MESSAGE:
                                g.P("msg := new(", fieldTypes[field][1:], ")") // drop star
                                lhs = "err"
                                dec = "b.DecodeMessage(msg)"
                                // handled specially below
                        case descriptor.FieldDescriptorProto_TYPE_BYTES:
                                dec = "b.DecodeRawBytes(true)"
                        case descriptor.FieldDescriptorProto_TYPE_UINT32:
                                dec, cast = "b.DecodeVarint()", "uint32"
                        case descriptor.FieldDescriptorProto_TYPE_ENUM:
                                dec, cast = "b.DecodeVarint()", fieldTypes[field]
                        case descriptor.FieldDescriptorProto_TYPE_SFIXED32:
                                dec, cast = "b.DecodeFixed32()", "int32"
                        case descriptor.FieldDescriptorProto_TYPE_SFIXED64:
                                dec, cast = "b.DecodeFixed64()", "int64"
                        case descriptor.FieldDescriptorProto_TYPE_SINT32:
                                dec, cast = "b.DecodeZigzag32()", "int32"
                        case descriptor.FieldDescriptorProto_TYPE_SINT64:
                                dec, cast = "b.DecodeZigzag64()", "int64"
                        default:
                                g.Fail("unhandled oneof field type ", field.Type.String())
                        }
                        g.P(lhs, " := ", dec)
                        val := "x"
                        if cast != "" {
                                val = cast + "(" + val + ")"
                        }
                        if cast2 != "" {
                                val = cast2 + "(" + val + ")"
                        }
                        switch *field.Type {
                        case descriptor.FieldDescriptorProto_TYPE_BOOL:
                                val += " != 0"
                        case descriptor.FieldDescriptorProto_TYPE_GROUP,
                                descriptor.FieldDescriptorProto_TYPE_MESSAGE:
                                val = "msg"
                        }
                        g.P("m.", oneofFieldName[*field.OneofIndex], " = &", oneofTypeName[field], "{", val, "}")
                        g.P("return true, err")
                }
                g.P("default: return false, nil")
                g.P("}")
                g.P("}")
                g.P()

                // sizer
                g.P("func ", size, sizeSig, " {")
                g.P("m := msg.(*", ccTypeName, ")")
                for oi, odp := range message.OneofDecl {
                        g.P("// ", odp.GetName())
                        fname := oneofFieldName[int32(oi)]
                        g.P("switch x := m.", fname, ".(type) {")
                        for _, field := range message.Field {
                                if field.OneofIndex == nil || int(*field.OneofIndex) != oi {
                                        continue
                                }
                                g.P("case *", oneofTypeName[field], ":")
                                val := "x." + fieldNames[field]
                                var wire, varint, fixed string
                                switch *field.Type {
                                case descriptor.FieldDescriptorProto_TYPE_DOUBLE:
                                        wire = "WireFixed64"
                                        fixed = "8"
                                case descriptor.FieldDescriptorProto_TYPE_FLOAT:
                                        wire = "WireFixed32"
                                        fixed = "4"
                                case descriptor.FieldDescriptorProto_TYPE_INT64,
                                        descriptor.FieldDescriptorProto_TYPE_UINT64,
                                        descriptor.FieldDescriptorProto_TYPE_INT32,
                                        descriptor.FieldDescriptorProto_TYPE_UINT32,
                                        descriptor.FieldDescriptorProto_TYPE_ENUM:
                                        wire = "WireVarint"
                                        varint = val
                                case descriptor.FieldDescriptorProto_TYPE_FIXED64,
                                        descriptor.FieldDescriptorProto_TYPE_SFIXED64:
                                        wire = "WireFixed64"
                                        fixed = "8"
                                case descriptor.FieldDescriptorProto_TYPE_FIXED32,
                                        descriptor.FieldDescriptorProto_TYPE_SFIXED32:
                                        wire = "WireFixed32"
                                        fixed = "4"
                                case descriptor.FieldDescriptorProto_TYPE_BOOL:
                                        wire = "WireVarint"
                                        fixed = "1"
                                case descriptor.FieldDescriptorProto_TYPE_STRING:
                                        wire = "WireBytes"
                                        fixed = "len(" + val + ")"
                                        varint = fixed
                                case descriptor.FieldDescriptorProto_TYPE_GROUP:
                                        wire = "WireStartGroup"
                                        fixed = g.Pkg["proto"] + ".Size(" + val + ")"
                                case descriptor.FieldDescriptorProto_TYPE_MESSAGE:
                                        wire = "WireBytes"
                                        g.P("s := ", g.Pkg["proto"], ".Size(", val, ")")
                                        fixed = "s"
                                        varint = fixed
                                case descriptor.FieldDescriptorProto_TYPE_BYTES:
                                        wire = "WireBytes"
                                        fixed = "len(" + val + ")"
                                        varint = fixed
                                case descriptor.FieldDescriptorProto_TYPE_SINT32:
                                        wire = "WireVarint"
                                        varint = "(uint32(" + val + ") << 1) ^ uint32((int32(" + val + ") >> 31))"
                                case descriptor.FieldDescriptorProto_TYPE_SINT64:
                                        wire = "WireVarint"
                                        varint = "uint64(" + val + " << 1) ^ uint64((int64(" + val + ") >> 63))"
                                default:
                                        g.Fail("unhandled oneof field type ", field.Type.String())
                                }
                                g.P("n += ", g.Pkg["proto"], ".SizeVarint(", field.Number, "<<3|", g.Pkg["proto"], ".", wire, ")")
                                if varint != "" {
                                        g.P("n += ", g.Pkg["proto"], ".SizeVarint(uint64(", varint, "))")
                                }
                                if fixed != "" {
                                        g.P("n += ", fixed)
                                }
                                if *field.Type == descriptor.FieldDescriptorProto_TYPE_GROUP {
                                        g.P("n += ", g.Pkg["proto"], ".SizeVarint(", field.Number, "<<3|", g.Pkg["proto"], ".WireEndGroup)")
                                }
                        }
                        g.P("case nil:")
                        g.P("default:")
                        g.P("panic(", g.Pkg["fmt"], ".Sprintf(\"proto: unexpected type %T in oneof\", x))")
                        g.P("}")
                }
                g.P("return n")
                g.P("}")
                g.P()
        }

        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"], ccTypeName, fullName)
}

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.
        mset := false
        if extendedType == "*proto2_bridge.MessageSet" && typeName[len(typeName)-1] == "message_set_extension" {
                typeName = typeName[:len(typeName)-1]
                mset = true
        }

        // 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.In()
        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.Out()
        g.P("}")
        g.P()

        if mset {
                // Generate a bit more code to register with message_set.go.
                g.addInitf("%s.RegisterMessageSetType((%s)(nil), %d, %q)", g.Pkg["proto"], fieldType, *field.Number, extName)
        }

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

func (g *Generator) generateInitFunction() {
        for _, enum := range g.file.enum {
                g.generateEnumRegistration(enum)
        }
        for _, d := range g.file.desc {
                for _, ext := range d.ext {
                        g.generateExtensionRegistration(ext)
                }
        }
        for _, ext := range g.file.ext {
                g.generateExtensionRegistration(ext)
        }
        if len(g.init) == 0 {
                return
        }
        g.P("func init() {")
        g.In()
        for _, l := range g.init {
                g.P(l)
        }
        g.Out()
        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.In()
        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.Out()
        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)
}

func (g *Generator) generateExtensionRegistration(ext *ExtensionDescriptor) {
        g.addInitf("%s.RegisterExtension(%s)", g.Pkg["proto"], ext.DescName())
}

// 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
)