Cacher is the code snippet organizer for pro developers

package main

import (
	"fmt"
	"io"
	"io/ioutil"
	"log"
	"os"

	"github.com/golang/protobuf/proto"
	pb "github.com/protocolbuffers/protobuf/examples/tutorial"
)

func writePerson(w io.Writer, p *pb.Person) {
	fmt.Fprintln(w, "Person ID:", p.Id)
	fmt.Fprintln(w, "  Name:", p.Name)
	if p.Email != "" {
		fmt.Fprintln(w, "  E-mail address:", p.Email)
	}

	for _, pn := range p.Phones {
		switch pn.Type {
		case pb.Person_MOBILE:
			fmt.Fprint(w, "  Mobile phone #: ")
		case pb.Person_HOME:
			fmt.Fprint(w, "  Home phone #: ")
		case pb.Person_WORK:
			fmt.Fprint(w, "  Work phone #: ")
		}
		fmt.Fprintln(w, pn.Number)
	}
}

func listPeople(w io.Writer, book *pb.AddressBook) {
	for _, p := range book.People {
		writePerson(w, p)
	}
}

// Main reads the entire address book from a file and prints all the
// information inside.
func main() {
	if len(os.Args) != 2 {
		log.Fatalf("Usage:  %s ADDRESS_BOOK_FILE\n", os.Args[0])
	}
	fname := os.Args[1]

	// [START unmarshal_proto]
	// Read the existing address book.
	in, err := ioutil.ReadFile(fname)
	if err != nil {
		log.Fatalln("Error reading file:", err)
	}
	book := &pb.AddressBook{}
	if err := proto.Unmarshal(in, book); err != nil {
		log.Fatalln("Failed to parse address book:", err)
	}
	// [END unmarshal_proto]

	listPeople(os.Stdout, book)
}

package main

import (
	"bufio"
	"fmt"
	"io"
	"io/ioutil"
	"log"
	"os"
	"strings"

	"github.com/golang/protobuf/proto"
	pb "github.com/protocolbuffers/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]
}

package main

import (
	"strings"
	"testing"

	"github.com/golang/protobuf/proto"
	pb "github.com/protocolbuffers/protobuf/examples/tutorial"
)

func TestPromptForAddressReturnsAddress(t *testing.T) {
	in := `12345
Example Name
name@example.com
123-456-7890
home
222-222-2222
mobile
111-111-1111
work
777-777-7777
unknown

`
	got, err := promptForAddress(strings.NewReader(in))
	if err != nil {
		t.Fatalf("promptForAddress(%q) had unexpected error: %s", in, err.Error())
	}
	if got.Id != 12345 {
		t.Errorf("promptForAddress(%q) got %d, want ID %d", in, got.Id, 12345)
	}
	if got.Name != "Example Name" {
		t.Errorf("promptForAddress(%q) => want name %q, got %q", in, "Example Name", got.Name)
	}
	if got.Email != "name@example.com" {
		t.Errorf("promptForAddress(%q) => want email %q, got %q", in, "name@example.com", got.Email)
	}

	want := []*pb.Person_PhoneNumber{
		{Number: "123-456-7890", Type: pb.Person_HOME},
		{Number: "222-222-2222", Type: pb.Person_MOBILE},
		{Number: "111-111-1111", Type: pb.Person_WORK},
		{Number: "777-777-7777", Type: pb.Person_MOBILE},
	}
	if len(got.Phones) != len(want) {
		t.Errorf("want %d phone numbers, got %d", len(want), len(got.Phones))
	}
	phones := len(got.Phones)
	if phones > len(want) {
		phones = len(want)
	}
	for i := 0; i < phones; i++ {
		if !proto.Equal(got.Phones[i], want[i]) {
			t.Errorf("want phone %q, got %q", *want[i], *got.Phones[i])
		}

	}
}

package main

import (
	"bytes"
	"strings"
	"testing"

	pb "github.com/protocolbuffers/protobuf/examples/tutorial"
)

func TestWritePersonWritesPerson(t *testing.T) {
	buf := new(bytes.Buffer)
	// [START populate_proto]
	p := pb.Person{
		Id:    1234,
		Name:  "John Doe",
		Email: "jdoe@example.com",
		Phones: []*pb.Person_PhoneNumber{
			{Number: "555-4321", Type: pb.Person_HOME},
		},
	}
	// [END populate_proto]
	writePerson(buf, &p)
	got := buf.String()
	want := `Person ID: 1234
  Name: John Doe
  E-mail address: jdoe@example.com
  Home phone #: 555-4321
`
	if got != want {
		t.Errorf("writePerson(%s) =>\n\t%q, want %q", p.String(), got, want)
	}
}

func TestListPeopleWritesList(t *testing.T) {
	buf := new(bytes.Buffer)
	in := pb.AddressBook{People: []*pb.Person{
		{
			Name:  "John Doe",
			Id:    101,
			Email: "john@example.com",
		},
		{
			Name: "Jane Doe",
			Id:   102,
		},
		{
			Name:  "Jack Doe",
			Id:    201,
			Email: "jack@example.com",
			Phones: []*pb.Person_PhoneNumber{
				{Number: "555-555-5555", Type: pb.Person_WORK},
			},
		},
		{
			Name:  "Jack Buck",
			Id:    301,
			Email: "buck@example.com",
			Phones: []*pb.Person_PhoneNumber{
				{Number: "555-555-0000", Type: pb.Person_HOME},
				{Number: "555-555-0001", Type: pb.Person_MOBILE},
				{Number: "555-555-0002", Type: pb.Person_WORK},
			},
		},
		{
			Name:  "Janet Doe",
			Id:    1001,
			Email: "janet@example.com",
			Phones: []*pb.Person_PhoneNumber{
				{Number: "555-777-0000"},
				{Number: "555-777-0001", Type: pb.Person_HOME},
			},
		},
	}}
	listPeople(buf, &in)
	want := strings.Split(`Person ID: 101
  Name: John Doe
  E-mail address: john@example.com
Person ID: 102
  Name: Jane Doe
Person ID: 201
  Name: Jack Doe
  E-mail address: jack@example.com
  Work phone #: 555-555-5555
Person ID: 301
  Name: Jack Buck
  E-mail address: buck@example.com
  Home phone #: 555-555-0000
  Mobile phone #: 555-555-0001
  Work phone #: 555-555-0002
Person ID: 1001
  Name: Janet Doe
  E-mail address: janet@example.com
  Mobile phone #: 555-777-0000
  Home phone #: 555-777-0001
`, "\n")
	got := strings.Split(buf.String(), "\n")
	if len(got) != len(want) {
		t.Errorf(
			"listPeople(%s) =>\n\t%q has %d lines, want %d",
			in.String(),
			buf.String(),
			len(got),
			len(want))
	}
	lines := len(got)
	if lines > len(want) {
		lines = len(want)
	}
	for i := 0; i < lines; i++ {
		if got[i] != want[i] {
			t.Errorf(
				"listPeople(%s) =>\n\tline %d %q, want %q",
				in.String(),
				i,
				got[i],
				want[i])
		}
	}
}

# See README.txt.

.PHONY: all go clean

all: go
go:     add_person_go     list_people_go
	echo "xxx"

gotest: add_person_gotest list_people_gotest

clean:
	rm -f add_person_cpp list_people_cpp add_person_java list_people_java add_person_python list_people_python
	rm -f javac_middleman AddPerson*.class ListPeople*.class com/example/tutorial/*.class
	rm -f protoc_middleman addressbook.pb.cc addressbook.pb.h addressbook_pb2.py com/example/tutorial/AddressBookProtos.java
	rm -f *.pyc
	rm -f protoc_middleman_go tutorial/*.pb.go add_person_go list_people_go
	rm -f protoc_middleman_dart dart_tutorial/*.pb*.dart
	rmdir dart_tutorial 2>/dev/null || true
	rmdir tutorial 2>/dev/null || true
	rmdir com/example/tutorial 2>/dev/null || true
	rmdir com/example 2>/dev/null || true
	rmdir com 2>/dev/null || true

protoc_middleman_go: addressbook.proto
	mkdir -p tutorial # make directory for go package
	protoc $$PROTO_PATH --go_out=tutorial addressbook.proto
	@touch protoc_middleman_go

add_person_go: add_person.go protoc_middleman_go
	go build -o add_person_go add_person.go

add_person_gotest: add_person_test.go add_person_go
	go test add_person.go add_person_test.go

list_people_go: list_people.go protoc_middleman_go
	go build -o list_people_go list_people.go

list_people_gotest: list_people.go list_people_go
	go test list_people.go list_people_test.go

// See README.txt for information and build instructions.
//
// Note: START and END tags are used in comments to define sections used in
// tutorials.  They are not part of the syntax for Protocol Buffers.
//
// To get an in-depth walkthrough of this file and the related examples, see:
// https://developers.google.com/protocol-buffers/docs/tutorials

// [START declaration]
syntax = "proto3";
package tutorial;

import "google/protobuf/timestamp.proto";
// [END declaration]

// [START java_declaration]
option java_package = "com.example.tutorial";
option java_outer_classname = "AddressBookProtos";
// [END java_declaration]

// [START csharp_declaration]
option csharp_namespace = "Google.Protobuf.Examples.AddressBook";
// [END csharp_declaration]

// [START messages]
message Person {
  string name = 1;
  int32 id = 2;  // Unique ID number for this person.
  string email = 3;

  enum PhoneType {
    MOBILE = 0;
    HOME = 1;
    WORK = 2;
  }

  message PhoneNumber {
    string number = 1;
    PhoneType type = 2;
  }

  repeated PhoneNumber phones = 4;

  google.protobuf.Timestamp last_updated = 5;
}

// Our address book file is just one of these.
message AddressBook {
  repeated Person people = 1;
}
// [END messages]