lisp/diff.el

   1 ;;; diff.el --- run `diff' in compilation-mode
   2
   3 ;; Copyright (C) 1992, 1994, 1996, 2001, 2002, 2003, 2004,
   4 ;;   2005, 2006, 2007 Free Software Foundation, Inc.
   5
   6 ;; Maintainer: FSF
   7 ;; Keywords: unix, tools
   8
   9 ;; This file is part of GNU Emacs.
  10
  11 ;; GNU Emacs is free software; you can redistribute it and/or modify
  12 ;; it under the terms of the GNU General Public License as published by
  13 ;; the Free Software Foundation; either version 2, or (at your option)
  14 ;; any later version.
  15
  16 ;; GNU Emacs is distributed in the hope that it will be useful,
  17 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  18 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19 ;; GNU General Public License for more details.
  20
  21 ;; You should have received a copy of the GNU General Public License
  22 ;; along with GNU Emacs; see the file COPYING.  If not, write to the
  23 ;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  24 ;; Boston, MA 02110-1301, USA.
  25
  26 ;;; Commentary:
  27
  28 ;; This package helps you explore differences between files, using the
  29 ;; UNIX command diff(1).  The commands are `diff' and `diff-backup'.
  30 ;; You can specify options with `diff-switches'.
  31
  32 ;;; Code:
  33
  34 (defgroup diff nil
  35   "Comparing files with `diff'."
  36   :group 'tools)
  37
  38 ;;;###autoload
  39 (defcustom diff-switches "-c"
  40   "*A string or list of strings specifying switches to be passed to diff."
  41   :type '(choice string (repeat string))
  42   :group 'diff)
  43
  44 ;;;###autoload
  45 (defcustom diff-command "diff"
  46   "*The command to use to run diff."
  47   :type 'string
  48   :group 'diff)
  49
  50 (defvar diff-old-temp-file nil
  51   "This is the name of a temp file to be deleted after diff finishes.")
  52 (defvar diff-new-temp-file nil
  53   "This is the name of a temp file to be deleted after diff finishes.")
  54
  55 ;; prompt if prefix arg present
  56 (defun diff-switches ()
  57   (if current-prefix-arg
  58       (read-string "Diff switches: "
  59                    (if (stringp diff-switches)
  60                        diff-switches
  61                      (mapconcat 'identity diff-switches " ")))))
  62
  63 (defun diff-sentinel (code)
  64   "Code run when the diff process exits.
  65 CODE is the exit code of the process.  It should be 0 iff no diffs were found."
  66   (if diff-old-temp-file (delete-file diff-old-temp-file))
  67   (if diff-new-temp-file (delete-file diff-new-temp-file))
  68   (save-excursion
  69     (goto-char (point-max))
  70     (let ((inhibit-read-only t))
  71       (insert (format "\nDiff finished%s.  %s\n"
  72                       (if (equal 0 code) " (no differences)" "")
  73                       (current-time-string))))))
  74
  75 ;;;###autoload
  76 (defun diff (old new &optional switches no-async)
  77   "Find and display the differences between OLD and NEW files.
  78 Interactively the current buffer's file name is the default for NEW
  79 and a backup file for NEW is the default for OLD.
  80 If NO-ASYNC is non-nil, call diff synchronously.
  81 With prefix arg, prompt for diff switches."
  82   (interactive
  83    (let (oldf newf)
  84      (setq newf (buffer-file-name)
  85            newf (if (and newf (file-exists-p newf))
  86                     (read-file-name
  87                      (concat "Diff new file (default "
  88                              (file-name-nondirectory newf) "): ")
  89                      nil newf t)
  90                   (read-file-name "Diff new file: " nil nil t)))
  91      (setq oldf (file-newest-backup newf)
  92            oldf (if (and oldf (file-exists-p oldf))
  93                     (read-file-name
  94                      (concat "Diff original file (default "
  95                              (file-name-nondirectory oldf) "): ")
  96                      (file-name-directory oldf) oldf t)
  97                   (read-file-name "Diff original file: "
  98                                   (file-name-directory newf) nil t)))
  99      (list oldf newf (diff-switches))))
 100   (setq new (expand-file-name new)
 101         old (expand-file-name old))
 102   (or switches (setq switches diff-switches)) ; If not specified, use default.
 103   (let* ((old-alt (file-local-copy old))
 104         (new-alt (file-local-copy new))
 105          (command
 106           (mapconcat 'identity
 107                      `(,diff-command
 108                        ;; Use explicitly specified switches
 109                        ,@(if (listp switches) switches (list switches))
 110                        ,@(if (or old-alt new-alt)
 111                              (list "-L" old "-L" new))
 112                        ,(shell-quote-argument (or old-alt old))
 113                        ,(shell-quote-argument (or new-alt new)))
 114                      " "))
 115          (buf (get-buffer-create "*Diff*"))
 116          (thisdir default-directory)
 117          proc)
 118     (save-excursion
 119       (display-buffer buf)
 120       (set-buffer buf)
 121       (setq buffer-read-only nil)
 122       (buffer-disable-undo (current-buffer))
 123       (let ((inhibit-read-only t))
 124         (erase-buffer))
 125       (buffer-enable-undo (current-buffer))
 126       (diff-mode)
 127       (set (make-local-variable 'revert-buffer-function)
 128            `(lambda (ignore-auto noconfirm)
 129               (diff ',old ',new ',switches ',no-async)))
 130       (set (make-local-variable 'diff-old-temp-file) old-alt)
 131       (set (make-local-variable 'diff-new-temp-file) new-alt)
 132       (setq default-directory thisdir)
 133       (let ((inhibit-read-only t))
 134         (insert command "\n"))
 135       (if (and (not no-async) (fboundp 'start-process))
 136           (progn
 137             (setq proc (start-process "Diff" buf shell-file-name
 138                                       shell-command-switch command))
 139             (set-process-filter proc 'diff-process-filter)
 140             (set-process-sentinel
 141              proc (lambda (proc msg)
 142                     (with-current-buffer (process-buffer proc)
 143                       (diff-sentinel (process-exit-status proc))))))
 144         ;; Async processes aren't available.
 145         (let ((inhibit-read-only t))
 146           (diff-sentinel
 147            (call-process shell-file-name nil buf nil
 148                          shell-command-switch command)))))
 149     buf))
 150
 151 (defun diff-process-filter (proc string)
 152   (with-current-buffer (process-buffer proc)
 153     (let ((moving (= (point) (process-mark proc))))
 154       (save-excursion
 155         ;; Insert the text, advancing the process marker.
 156         (goto-char (process-mark proc))
 157         (let ((inhibit-read-only t))
 158           (insert string))
 159         (set-marker (process-mark proc) (point)))
 160       (if moving (goto-char (process-mark proc))))))
 161
 162 ;;;###autoload
 163 (defun diff-backup (file &optional switches)
 164   "Diff this file with its backup file or vice versa.
 165 Uses the latest backup, if there are several numerical backups.
 166 If this file is a backup, diff it with its original.
 167 The backup file is the first file given to `diff'.
 168 With prefix arg, prompt for diff switches."
 169   (interactive (list (read-file-name "Diff (file with backup): ")
 170                      (diff-switches)))
 171   (let (bak ori)
 172     (if (backup-file-name-p file)
 173         (setq bak file
 174               ori (file-name-sans-versions file))
 175       (setq bak (or (diff-latest-backup-file file)
 176                     (error "No backup found for %s" file))
 177             ori file))
 178     (diff bak ori switches)))
 179
 180 (defun diff-latest-backup-file (fn)     ; actually belongs into files.el
 181   "Return the latest existing backup of FILE, or nil."
 182   (let ((handler (find-file-name-handler fn 'diff-latest-backup-file)))
 183     (if handler
 184         (funcall handler 'diff-latest-backup-file fn)
 185       (file-newest-backup fn))))
 186
 187 (provide 'diff)
 188
 189 ;;; arch-tag: 7de2c29b-7ea5-4b85-9b9d-72dd860de2bd
 190 ;;; diff.el ends here