gistfile1.go

package main

import "github.com/sergi/go-diff/diffmatchpatch"

import "bytes"
import "os"
import "os/exec"
import "io/ioutil"

func diff_native(s1, s2 string) string {
	dmp := diffmatchpatch.New()
	return dmp.PatchToText(dmp.PatchMake(s1, s2))
}

func diff_not_native(s1, s2 string) string {
	if data, err := diff_gofmt([]byte(s1), []byte(s2)); err == nil {
		data = data[bytes.IndexByte(data, '\n')+1:] // Skip first line
		data = data[bytes.IndexByte(data, '\n')+1:] // Skip second line
		return string(data)
	} else {
		panic(err)
	}
}
func diff_gofmt(b1, b2 []byte) (data []byte, err error) {
	f1, err := ioutil.TempFile("", "gofmt")
	if err != nil {
		return
	}
	defer os.Remove(f1.Name())
	defer f1.Close()

	f2, err := ioutil.TempFile("", "gofmt")
	if err != nil {
		return
	}
	defer os.Remove(f2.Name())
	defer f2.Close()

	f1.Write(b1)
	f2.Write(b2)

	data, err = exec.Command("diff", "-u", f1.Name(), f2.Name()).CombinedOutput()
	if len(data) > 0 {
		// diff exits with a non-zero status when the files don't match.
		// Ignore that failure as long as we get output.
		err = nil
	}
	return

}

var s1, s2 = `package main

import (
	"fmt"
	"io/ioutil"
	"net/http"
	"time"
)

const Const = 1 + 1

type Bar struct {
	key   string
	value int
}

func foo() (int, string) { return 5, "hi" }

func handler(w http.ResponseWriter, r *http.Request) {
	b, err := ioutil.ReadAll(r.Body)
	_ = b
	_ = err
}

func main() {
	foo()
	fmt.Println("Booyah!!!!!!!!!!!!!!!!!!!!!!!!!!!!")
	for i := 1; i <= 10; i++ {
		time.Sleep(100 * time.Millisecond)
		fmt.Println(i)
	}
	i := Bar{"i", 1236}
	i.value++
}
`, `package main

import (
	"fmt"
	"io/ioutil"
	"net/http"
	"time"
)

const Const = 1 + 1

type Bar struct {
	key   string
	value int
}

func foo() (int, string) { return 5, "hi" }

func handler(w http.ResponseWriter, r *http.Request) {
	b, err := ioutil.ReadAll(r.Body)
	_ = b
	_ = err
}

func main() {
	foo()
	fmt.Println("Booyah!!!!!!!!!!!!!!!!!!!!!!!!!!")
	for i := 1; i <= 10; i++ {
		time.Sleep(100 * time.Millisecond)
		fmt.Println(i)
	}
	i := Bar{"i", 1236}
	i.value++
}
`

func main() {
	output := diff_native(s1, s2)
	desiredOutput := diff_not_native(s1, s2)

	if output == desiredOutput {
		print("Victory! Thank you for playing.")
	} else {
		print("got:\n", output)
		print("\ndesired:\n", desiredOutput)
	}
}