Sha256: a18b2f37c81fdd7c45dc957ee5f1cd6dd63e003d25d40c1bb3e356d9d1a4c9d2
Contents?: true
Size: 1.42 KB
Versions: 396
Compression:
Stored size: 1.42 KB
Contents
;;; atbash-cipher.el --- Atbash-Cipher (exercism)
;;; Commentary:
;;;
;;; Adapted from the Common Lisp example, at
;;; https://github.com/exercism/xlisp/blob/master/atbash-cipher/example.lisp
;;; Code:
(defun encode (plaintext)
"Encode PLAINTEXT to atbash-cipher encoding."
(to-string (group (to-cipher-seq plaintext))))
(defun to-string (seq)
"Convert SEQ of characters to a string."
(concatenate 'string seq))
(defun group (seq &optional group-size)
"Group SEQ into chunks of size GROUP-SIZE."
(let ((length (or group-size 5)))
(loop
for c in seq and i from 1
collect c
when (and (not (= i (length seq)))
(zerop (mod i length)))
collect ?\ )))
(defun to-cipher-seq (plaintext)
"Convert PLAINTEXT to a ciphered sequence."
(cleanup-ciphered-seq (map 'list #'encipher plaintext)))
(defun cleanup-ciphered-seq (seq)
"Clean values of char code 0 from SEQ."
(remove 0 seq))
(defun encipher (c)
"Encipher the character C."
(cond ((alpha-char-p c) (opposite-char (downcase c)))
((digit-char-p c) c)
(t 0)))
(defun digit-char-p (c)
"Determine if char C is numeric."
(and
(>= c ?0)
(<= c ?9)))
(defun alpha-char-p (c)
"Determine if char C is alphabetic."
(and
(>= c ?A)
(<= c ?z)))
(defun opposite-char (c)
"Find the opposite char of argument character C."
(- ?z
(- c ?a)))
(provide 'atbash-cipher)
;;; atbash-cipher.el ends here
Version data entries
396 entries across 396 versions & 1 rubygems