lisp/vc/diff.el

   1 ;;; diff.el --- run `diff' in compilation-mode
   2
   3 ;; Copyright (C) 1992, 1994, 1996, 2001-2011 Free Software Foundation, Inc.
   4
   5 ;; Author: Frank Bresz
   6 ;; (according to authors.el)
   7 ;; Maintainer: FSF
   8 ;; Keywords: unix, vc, tools
   9
  10 ;; This file is part of GNU Emacs.
  11
  12 ;; GNU Emacs is free software: you can redistribute it and/or modify
  13 ;; it under the terms of the GNU General Public License as published by
  14 ;; the Free Software Foundation, either version 3 of the License, or
  15 ;; (at your option) any later version.
  16
  17 ;; GNU Emacs is distributed in the hope that it will be useful,
  18 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  19 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20 ;; GNU General Public License for more details.
  21
  22 ;; You should have received a copy of the GNU General Public License
  23 ;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
  24
  25 ;;; Commentary:
  26
  27 ;; This package helps you explore differences between files, using the
  28 ;; UNIX command diff(1).  The commands are `diff' and `diff-backup'.
  29 ;; You can specify options with `diff-switches'.
  30
  31 ;;; Code:
  32
  33 (eval-when-compile (require 'cl))
  34
  35 (defgroup diff nil
  36   "Comparing files with `diff'."
  37   :group 'tools)
  38
  39 ;;;###autoload
  40 (defcustom diff-switches (purecopy "-c")
  41   "A string or list of strings specifying switches to be passed to diff."
  42   :type '(choice string (repeat string))
  43   :group 'diff)
  44
  45 ;;;###autoload
  46 (defcustom diff-command (purecopy "diff")
  47   "The command to use to run diff."
  48   :type 'string
  49   :group 'diff)
  50
  51 ;; prompt if prefix arg present
  52 (defun diff-switches ()
  53   (if current-prefix-arg
  54       (read-string "Diff switches: "
  55                    (if (stringp diff-switches)
  56                        diff-switches
  57                      (mapconcat 'identity diff-switches " ")))))
  58
  59 (defun diff-sentinel (code &optional old-temp-file new-temp-file)
  60   "Code run when the diff process exits.
  61 CODE is the exit code of the process.  It should be 0 only if no diffs
  62 were found.
  63 If optional args OLD-TEMP-FILE and/or NEW-TEMP-FILE are non-nil,
  64 delete the temporary files so named."
  65   (if old-temp-file (delete-file old-temp-file))
  66   (if new-temp-file (delete-file new-temp-file))
  67   (save-excursion
  68     (goto-char (point-max))
  69     (let ((inhibit-read-only t))
  70       (insert (format "\nDiff finished%s.  %s\n"
  71                       (cond ((equal 0 code) " (no differences)")
  72                             ((equal 2 code) " (diff error)")
  73                             (t ""))
  74                       (current-time-string))))))
  75
  76 ;;;###autoload
  77 (defun diff (old new &optional switches no-async)
  78   "Find and display the differences between OLD and NEW files.
  79 When called interactively, read OLD and NEW using the minibuffer;
  80 the default for NEW is the current buffer's file name, and the
  81 default for OLD is a backup file for NEW, if one exists.
  82 If NO-ASYNC is non-nil, call diff synchronously.
  83
  84 When called interactively with a prefix argument, prompt
  85 interactively for diff switches.  Otherwise, the switches
  86 specified in `diff-switches' are passed to the diff command."
  87   (interactive
  88    (let* ((newf (if (and buffer-file-name (file-exists-p buffer-file-name))
  89                     (read-file-name
  90                      (concat "Diff new file (default "
  91                              (file-name-nondirectory buffer-file-name) "): ")
  92                      nil buffer-file-name t)
  93                   (read-file-name "Diff new file: " nil nil t)))
  94           (oldf (file-newest-backup newf)))
  95      (setq oldf (if (and oldf (file-exists-p oldf))
  96                     (read-file-name
  97                      (concat "Diff original file (default "
  98                              (file-name-nondirectory oldf) "): ")
  99                      (file-name-directory oldf) oldf t)
 100                   (read-file-name "Diff original file: "
 101                                   (file-name-directory newf) nil t)))
 102      (list oldf newf (diff-switches))))
 103   (display-buffer
 104    (diff-no-select old new switches no-async)))
 105
 106 (defun diff-file-local-copy (file-or-buf)
 107   (if (bufferp file-or-buf)
 108       (with-current-buffer file-or-buf
 109         (let ((tempfile (make-temp-file "buffer-content-")))
 110           (write-region nil nil tempfile nil 'nomessage)
 111           tempfile))
 112     (file-local-copy file-or-buf)))
 113
 114 (defun diff-no-select (old new &optional switches no-async buf)
 115   ;; Noninteractive helper for creating and reverting diff buffers
 116   (unless (bufferp new) (setq new (expand-file-name new)))
 117   (unless (bufferp old) (setq old (expand-file-name old)))
 118   (or switches (setq switches diff-switches)) ; If not specified, use default.
 119   (unless (listp switches) (setq switches (list switches)))
 120   (or buf (setq buf (get-buffer-create "*Diff*")))
 121   (let* ((old-alt (diff-file-local-copy old))
 122          (new-alt (diff-file-local-copy new))
 123          (command
 124           (mapconcat 'identity
 125                      `(,diff-command
 126                        ;; Use explicitly specified switches
 127                        ,@switches
 128                        ,@(mapcar #'shell-quote-argument
 129                                  (nconc
 130                                   (when (or old-alt new-alt)
 131                                     (list "-L" (if (stringp old)
 132                                                    old (prin1-to-string old))
 133                                           "-L" (if (stringp new)
 134                                                    new (prin1-to-string new))))
 135                                   (list (or old-alt old)
 136                                         (or new-alt new)))))
 137                      " "))
 138          (thisdir default-directory))
 139     (with-current-buffer buf
 140       (setq buffer-read-only t)
 141       (buffer-disable-undo (current-buffer))
 142       (let ((inhibit-read-only t))
 143         (erase-buffer))
 144       (buffer-enable-undo (current-buffer))
 145       (diff-mode)
 146       (set (make-local-variable 'revert-buffer-function)
 147            (lexical-let ((old old) (new new)
 148                          (switches switches)
 149                          (no-async no-async))
 150              (lambda (ignore-auto noconfirm)
 151                (diff-no-select old new switches no-async (current-buffer)))))
 152       (setq default-directory thisdir)
 153       (let ((inhibit-read-only t))
 154         (insert command "\n"))
 155       (if (and (not no-async) (fboundp 'start-process))
 156           (let ((proc (start-process "Diff" buf shell-file-name
 157                                      shell-command-switch command)))
 158             (set-process-filter proc 'diff-process-filter)
 159             (lexical-let ((old-alt old-alt) (new-alt new-alt))
 160               (set-process-sentinel
 161                proc (lambda (proc msg)
 162                       (with-current-buffer (process-buffer proc)
 163                         (diff-sentinel (process-exit-status proc)
 164                                        old-alt new-alt))))))
 165         ;; Async processes aren't available.
 166         (let ((inhibit-read-only t))
 167           (diff-sentinel
 168            (call-process shell-file-name nil buf nil
 169                          shell-command-switch command)
 170            old-alt new-alt))))
 171     buf))
 172
 173 (defun diff-process-filter (proc string)
 174   (with-current-buffer (process-buffer proc)
 175     (let ((moving (= (point) (process-mark proc))))
 176       (save-excursion
 177         ;; Insert the text, advancing the process marker.
 178         (goto-char (process-mark proc))
 179         (let ((inhibit-read-only t))
 180           (insert string))
 181         (set-marker (process-mark proc) (point)))
 182       (if moving (goto-char (process-mark proc))))))
 183
 184 ;;;###autoload
 185 (defun diff-backup (file &optional switches)
 186   "Diff this file with its backup file or vice versa.
 187 Uses the latest backup, if there are several numerical backups.
 188 If this file is a backup, diff it with its original.
 189 The backup file is the first file given to `diff'.
 190 With prefix arg, prompt for diff switches."
 191   (interactive (list (read-file-name "Diff (file with backup): ")
 192                      (diff-switches)))
 193   (let (bak ori)
 194     (if (backup-file-name-p file)
 195         (setq bak file
 196               ori (file-name-sans-versions file))
 197       (setq bak (or (diff-latest-backup-file file)
 198                     (error "No backup found for %s" file))
 199             ori file))
 200     (diff bak ori switches)))
 201
 202 (defun diff-latest-backup-file (fn)     ; actually belongs into files.el
 203   "Return the latest existing backup of FILE, or nil."
 204   (let ((handler (find-file-name-handler fn 'diff-latest-backup-file)))
 205     (if handler
 206         (funcall handler 'diff-latest-backup-file fn)
 207       (file-newest-backup fn))))
 208
 209 ;;;###autoload
 210 (defun diff-buffer-with-file (&optional buffer)
 211   "View the differences between BUFFER and its associated file.
 212 This requires the external program `diff' to be in your `exec-path'."
 213   (interactive "bBuffer: ")
 214   (with-current-buffer (get-buffer (or buffer (current-buffer)))
 215     (diff buffer-file-name (current-buffer) nil 'noasync)))
 216
 217 (provide 'diff)
 218
 219 ;;; diff.el ends here