exercise2: rot13reader

exercises/rot13reader.go

@@ -0,0 +1,46 @@
+package main
+
+import (
+	"io"
+	"os"
+	"strings"
+)
+
+type rot13Reader struct {
+	r io.Reader
+}
+
+const capitalA = 65
+const capitalZ = 89
+const capitalMid = 77
+const A = 97
+const Z = 122
+const Mid = 109
+
+func (rot *rot13Reader) Read(b []byte) (n int, err error) {
+	n, err = rot.r.Read(b)
+
+	for i := 0; i < n; i++ {
+
+		if b[i] <= capitalZ && b[i] >= capitalA {
+			if b[i] <= capitalMid {
+				b[i] = b[i] + 13
+			} else {
+				b[i] = b[i] - 13
+			}
+		} else if b[i] <= Z && b[i] >= A {
+			if b[i] <= Mid {
+				b[i] = b[i] + 13
+			} else {
+				b[i] = b[i] - 13
+			}
+		}
+	}
+	return
+}
+
+func main() {
+	s := strings.NewReader("Lbh penpxrq gur pbqr!")
+	r := rot13Reader{s}
+	io.Copy(os.Stdout, &r)
+}