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- #!/run/current-system/profile/bin/guile \
- -e main -s
- !#
- (add-to-load-path (dirname (current-filename)))
- (use-modules (ice-9 getopt-long)
- (ice-9 textual-ports) ;;open-output-file
- (encrypt))
- (define (discover-shift amount)
- (let ((amount (string->number amount)))
- (if (not amount) ;; Only execute if the amount is a number.
- #f
- (let ((amount (abs amount)))
- (if (>= amount 26)
- (set! shift (modulo amount 26))
- (set! shift amount))))))
- ;; loop through each character in the file, and output the encrypted file
- (define (decrypt)
- (let ((char (get-char (current-input-port))
- (shift (discover-shift))))
- (when (not (eof-object? char))
- (if (char-alphabetic? char)
- (put-char (current-output-port)
- (encrypt shift char))
- (put-char (current-output-port) char))
- (decrypt))))
- (define (main args)
- ;;the option specification tells getopt-long how
- ;; to parse the command line
- (let* ((option-spec `((version (single-char #\v) (value #f))
- (help (single-char #\h) (value #f))
- (file (single-char #\f) (value #t)
- (predicate ,file-exists?))
- (shift (single-char #\s) (value #t)
- (predicate ,set-shift))))
- (program-name "decrypt")
- ;; tell getopt-long to parse the command line and put
- ;; the data in options
- (options (getopt-long args option-spec))
- (help-wanted (option-ref options 'help #f))
- (version-wanted (option-ref options 'version #f))
- (file-wanted (option-ref options 'file #f))
- (shift-wanted (option-ref options 'shift #f)))
- (if (or help-wanted version-wanted file-wanted)
- (cond
- (version-wanted (print-version program-name))
- (help-wanted (print-help program-name))
- (file-wanted
- (with-input-from-file file-wanted decrypt))))))
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