Tour of Go 2.0

Exercise: rot13Reader

A powerful pattern: an io.Reader that wraps another io.Reader and transforms the data as it flows through.

gzip.NewReader works this way — it takes a compressed stream and returns a decompressed one. Same interface, transformed data.

Your job: implement rot13Reader. It wraps an io.Reader and applies the ROT13 cipher to every alphabetical byte it reads.

The struct is already defined. Add a Read method that reads from r.r and shifts each letter by 13 positions.

main.go ▶ Run in Playground 
package main

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

type rot13Reader struct {
	r io.Reader
}

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