Update //third_party/protobuf to version 3.

third_party/protobuf/examples/add_person.go

+package main
+
+import (
+        "bufio"
+        "fmt"
+        "io"
+        "io/ioutil"
+        "log"
+        "os"
+        "strings"
+
+        "github.com/golang/protobuf/proto"
+        pb "github.com/google/protobuf/examples/tutorial"
+)
+
+func promptForAddress(r io.Reader) (*pb.Person, error) {
+        // A protocol buffer can be created like any struct.
+        p := &pb.Person{}
+
+        rd := bufio.NewReader(r)
+        fmt.Print("Enter person ID number: ")
+        // An int32 field in the .proto file is represented as an int32 field
+        // in the generated Go struct.
+        if _, err := fmt.Fscanf(rd, "%d\n", &p.Id); err != nil {
+                return p, err
+        }
+
+        fmt.Print("Enter name: ")
+        name, err := rd.ReadString('\n')
+        if err != nil {
+                return p, err
+        }
+        // A string field in the .proto file results in a string field in Go.
+        // We trim the whitespace because rd.ReadString includes the trailing
+        // newline character in its output.
+        p.Name = strings.TrimSpace(name)
+
+        fmt.Print("Enter email address (blank for none): ")
+        email, err := rd.ReadString('\n')
+        if err != nil {
+                return p, err
+        }
+        p.Email = strings.TrimSpace(email)
+
+        for {
+                fmt.Print("Enter a phone number (or leave blank to finish): ")
+                phone, err := rd.ReadString('\n')
+                if err != nil {
+                        return p, err
+                }
+                phone = strings.TrimSpace(phone)
+                if phone == "" {
+                        break
+                }
+                // The PhoneNumber message type is nested within the Person
+                // message in the .proto file.  This results in a Go struct
+                // named using the name of the parent prefixed to the name of
+                // the nested message.  Just as with pb.Person, it can be
+                // created like any other struct.
+                pn := &pb.Person_PhoneNumber{
+                        Number: phone,
+                }
+
+                fmt.Print("Is this a mobile, home, or work phone? ")
+                ptype, err := rd.ReadString('\n')
+                if err != nil {
+                        return p, err
+                }
+                ptype = strings.TrimSpace(ptype)
+
+                // A proto enum results in a Go constant for each enum value.
+                switch ptype {
+                case "mobile":
+                        pn.Type = pb.Person_MOBILE
+                case "home":
+                        pn.Type = pb.Person_HOME
+                case "work":
+                        pn.Type = pb.Person_WORK
+                default:
+                        fmt.Printf("Unknown phone type %q.  Using default.\n", ptype)
+                }
+
+                // A repeated proto field maps to a slice field in Go.  We can
+                // append to it like any other slice.
+                p.Phones = append(p.Phones, pn)
+        }
+
+        return p, nil
+}
+
+// Main reads the entire address book from a file, adds one person based on
+// user input, then writes it back out to the same file.
+func main() {
+        if len(os.Args) != 2 {
+                log.Fatalf("Usage:  %s ADDRESS_BOOK_FILE\n", os.Args[0])
+        }
+        fname := os.Args[1]
+
+        // Read the existing address book.
+        in, err := ioutil.ReadFile(fname)
+        if err != nil {
+                if os.IsNotExist(err) {
+                        fmt.Printf("%s: File not found.  Creating new file.\n", fname)
+                } else {
+                        log.Fatalln("Error reading file:", err)
+                }
+        }
+
+        // [START marshal_proto]
+        book := &pb.AddressBook{}
+        // [START_EXCLUDE]
+        if err := proto.Unmarshal(in, book); err != nil {
+                log.Fatalln("Failed to parse address book:", err)
+        }
+
+        // Add an address.
+        addr, err := promptForAddress(os.Stdin)
+        if err != nil {
+                log.Fatalln("Error with address:", err)
+        }
+        book.People = append(book.People, addr)
+        // [END_EXCLUDE]
+
+        // Write the new address book back to disk.
+        out, err := proto.Marshal(book)
+        if err != nil {
+                log.Fatalln("Failed to encode address book:", err)
+        }
+        if err := ioutil.WriteFile(fname, out, 0644); err != nil {
+                log.Fatalln("Failed to write address book:", err)
+        }
+        // [END marshal_proto]
+}