Tour of Go Rot13

rot13.go

package main

import (
	"io"
	"os"
	"strings"
	"unicode"
)

type rot13Reader struct {
	r io.Reader
}

func (rot *rot13Reader) Read(p []byte) (n int, err error) {
	n, err = rot.r.Read(p)
	for i := 0; i < len(p); i++ {
		v := p[i]
		is_upper := unicode.IsUpper(rune(v))
		is_lower := unicode.IsLower(rune(v))
		if is_upper || is_lower {
			a := byte('a')
			if is_upper {
				a = byte('A')
			}
			p[i] = (v-a+13)%26 + a
		}
	}

	return
}

func main() {
	s := strings.NewReader("Lbh penpxrq gur pbqr!")
	r := rot13Reader{s}
	io.Copy(os.Stdout, &r)
}