# $Id: rot13.tcl,v 1.2 2000/12/04 04:17:19 ams Exp $
# Copyright 2000 Abhijit Menon-Sen <ams@wiw.org>
#

proc rot {n} {
    global rots

    if {![info exists rots($n)]} {
        for {set i 0} {$i < 26} {incr i} {
            eval lappend ltr \
                [format "%c %c" [expr 65+$i] [expr 65+($i+$n)%26]] \
                [format "%c %c" [expr 97+$i] [expr 97+($i+$n)%26]]
        }
        set rots($n) $ltr
    }

    return $rots($n)
}

proc rotn {n s} {
    array set tr [rot $n]

    set l [string length $s]
    for {set i 0} {$i < $l} {incr i} { append t $tr([string index $s $i]) }

    return $t
}

proc rot13 {s} { return [rotn 13 $s] }