zcat.el, automatic uncompress of .Z file for GNU emacs [comp.emacs]

[Graham Gough]

Archive-name: zcat.el/graham
Original-posting-by: graham at r3.cs.man.ac.uk (Graham Gough)
Original-subject: Re: Automatic uncompress of .Z files?
Reposted-by: emv at math.lsa.umich.edu (Edward Vielmetti)

[This is an experimental alt.sources re-posting from the newsgroup(s)
comp.emacs. Comments on this service to emv at math.lsa.umich.edu 
(Edward Vielmetti).]


>From article <7365 at cs.utexas.edu>, by ctp at cs.utexas.edu (Clyde T. Poole):
> Sometime awhile back, I believe I saw a posting including some emacs
> lisp code to implement the automatic uncompress of .Z files (files
> compressed with the unix compress utility).  I would appreciate it if
> someone would provide me with the code or give me pointers to where I
> can find it.
> 

This  isn't the one that was posted then and isn't  the  most  elegant
piece  of  e-lisp  I've  ever  written,  but it's served me well for a
couple of years. I hope it does what is required,

Graham Gough

----------------------------------------------------------
Graham D. Gough, Department of Computer Science,
University of Manchester, Oxford Road, Manchester, M13 9PL, U.K.
Tel: (+44) 61-275 6277
JANET: graham at uk.ac.man.cs   USENET: ..ukc!man.cs.r3!graham

------------------------cut here ------------------------
;;
;; zcat.el
;;
;;; This file is not  part of GNU Emacs, however, GNU copyleft applies
;;
;; Visiting compressed files.
;;
;; Graham Gough (graham at uk.ac.man.cs.ux) 13/5/87
;; 
;; To use just load via .emacs, everything else is automatic
;;

(or (assoc "\\.Z$" auto-mode-alist)
    (setq auto-mode-alist (append  auto-mode-alist '(("\\.Z$" . zcat-buffer)))))

(defvar delete-compressed-files t "*Non-nil means delete the compressed version 
 of a file when a buffer is saved. Only has effect if original file visited
 was compressed.")

(defun delete-compressed-file ()
  "   Deletes (on confirmation) compressed version of file associated with
   current buffer"
  (interactive)
  (let ((fname (concat (buffer-file-name) ".Z"))
	ret)
    (if  (file-exists-p fname)
	(progn
	  (setq answer (yes-or-no-p (concat "Delete compressed file (" fname ")? ")))
	  (if answer 
	      (condition-case ()
		  (delete-file fname)
		(error
		 (message "Can't delete compressed file.")
		 (setq ret t))))))
    nil))

(defun zcat-buffer ()
  "   Uncompresses contents of buffer, respecting read-only status. Changes
   buffer-name, visited-file-name and mode appropriately. If buffer is saved, 
   compressed file is (optionally) deleted.
   Bug: Doesn't find an existing uncompressed buffer, creates a new one"
  (interactive)
  (let ((buf-stat buffer-read-only)	     ; remember read-only status
	(new-buf-name (substring (buffer-name) 0 -2)) ; get new buffer name
	(new-buf-fname (substring (buffer-file-name) 0 -2))) ; and file name
    (setq buffer-read-only nil)
    (message "Uncompressing %s .." (buffer-name))
    (shell-command-on-region (point-min) (point-max) "zcat" t)
    (message "Done")
    (setq buffer-read-only buf-stat)	     ; reinstate original
					     ; buffer-read-only status
    (rename-buffer
     (let ((newbname new-buf-name)
	   (counter 1))
       (while (get-buffer newbname)
	 (setq newbname
	       (concat new-buf-name "<" (prin1-to-string counter) ">"))
	 (setq counter (1+ counter)))
       newbname))			     ;  generate appropriate name.
    (set-visited-file-name new-buf-fname)
    (set-auto-mode)
    (if (not delete-compressed-files)
	nil
      (make-variable-buffer-local 'write-file-hooks)
      (setq write-file-hooks
	    (append write-file-hooks '(delete-compressed-file))))
    (set-buffer-modified-p nil)		     ; this means that auto-saves
					     ; and saves only take place
					     ; if buffer is really modified
    (goto-char (point-min))))