go-tour-61.go

package main

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

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++ {
        if (p[i] >= 'A' && p[i] <= 'M') || (p[i] >= 'a' && p[i] <= 'm') {
            p[i] += 13
        } else if (p[i] >= 'N' && p[i] <= 'Z') || (p[i] >= 'n' && p[i] <= 'z'){
            p[i] -= 13
        }
    }
    return
}

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