lisp/vc/diff.el

   1 ;;; diff.el --- run `diff' in compilation-mode
   2
   3 ;; Copyright (C) 1992, 1994, 1996, 2001, 2002, 2003, 2004, 2005, 2006,
   4 ;;   2007, 2008, 2009, 2010 Free Software Foundation, Inc.
   5
   6 ;; Author: Frank Bresz
   7 ;; (according to authors.el)
   8 ;; Maintainer: FSF
   9 ;; Keywords: unix, vc, tools
  10
  11 ;; This file is part of GNU Emacs.
  12
  13 ;; GNU Emacs is free software: you can redistribute it and/or modify
  14 ;; it under the terms of the GNU General Public License as published by
  15 ;; the Free Software Foundation, either version 3 of the License, or
  16 ;; (at your option) any later version.
  17
  18 ;; GNU Emacs is distributed in the hope that it will be useful,
  19 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  20 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  21 ;; GNU General Public License for more details.
  22
  23 ;; You should have received a copy of the GNU General Public License
  24 ;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
  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 (purecopy "-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 (purecopy "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 only if no diffs
  66 were found."
  67   (if diff-old-temp-file (delete-file diff-old-temp-file))
  68   (if diff-new-temp-file (delete-file diff-new-temp-file))
  69   (save-excursion
  70     (goto-char (point-max))
  71     (let ((inhibit-read-only t))
  72       (insert (format "\nDiff finished%s.  %s\n"
  73                       (cond ((equal 0 code) " (no differences)")
  74                             ((equal 2 code) " (diff error)")
  75                             (t ""))
  76                       (current-time-string))))))
  77
  78 (defvar diff-old-file nil)
  79 (defvar diff-new-file nil)
  80 (defvar diff-extra-args nil)
  81
  82 ;;;###autoload
  83 (defun diff (old new &optional switches no-async)
  84   "Find and display the differences between OLD and NEW files.
  85 When called interactively, read OLD and NEW using the minibuffer;
  86 the default for NEW is the current buffer's file name, and the
  87 default for OLD is a backup file for NEW, if one exists.
  88 If NO-ASYNC is non-nil, call diff synchronously.
  89
  90 When called interactively with a prefix argument, prompt
  91 interactively for diff switches.  Otherwise, the switches
  92 specified in `diff-switches' are passed to the diff command."
  93   (interactive
  94    (let (oldf newf)
  95      (setq newf (buffer-file-name)
  96            newf (if (and newf (file-exists-p newf))
  97                     (read-file-name
  98                      (concat "Diff new file (default "
  99                              (file-name-nondirectory newf) "): ")
 100                      nil newf t)
 101                   (read-file-name "Diff new file: " nil nil t)))
 102      (setq oldf (file-newest-backup newf)
 103            oldf (if (and oldf (file-exists-p oldf))
 104                     (read-file-name
 105                      (concat "Diff original file (default "
 106                              (file-name-nondirectory oldf) "): ")
 107                      (file-name-directory oldf) oldf t)
 108                   (read-file-name "Diff original file: "
 109                                   (file-name-directory newf) nil t)))
 110      (list oldf newf (diff-switches))))
 111   (setq new (expand-file-name new)
 112         old (expand-file-name old))
 113   (or switches (setq switches diff-switches)) ; If not specified, use default.
 114   (let* ((old-alt (file-local-copy old))
 115         (new-alt (file-local-copy new))
 116          (command
 117           (mapconcat 'identity
 118                      `(,diff-command
 119                        ;; Use explicitly specified switches
 120                        ,@(if (listp switches) switches (list switches))
 121                        ,@(if (or old-alt new-alt)
 122                              (list "-L" old "-L" new))
 123                        ,(shell-quote-argument (or old-alt old))
 124                        ,(shell-quote-argument (or new-alt new)))
 125                      " "))
 126          (buf (get-buffer-create "*Diff*"))
 127          (thisdir default-directory)
 128          proc)
 129     (save-excursion
 130       (display-buffer buf)
 131       (set-buffer buf)
 132       (setq buffer-read-only nil)
 133       (buffer-disable-undo (current-buffer))
 134       (let ((inhibit-read-only t))
 135         (erase-buffer))
 136       (buffer-enable-undo (current-buffer))
 137       (diff-mode)
 138       ;; Use below 2 vars for backward-compatibility.
 139       (set (make-local-variable 'diff-old-file) old)
 140       (set (make-local-variable 'diff-new-file) new)
 141       (set (make-local-variable 'diff-extra-args) (list switches no-async))
 142       (set (make-local-variable 'revert-buffer-function)
 143            (lambda (ignore-auto noconfirm)
 144              (apply 'diff diff-old-file diff-new-file diff-extra-args)))
 145       (set (make-local-variable 'diff-old-temp-file) old-alt)
 146       (set (make-local-variable 'diff-new-temp-file) new-alt)
 147       (setq default-directory thisdir)
 148       (let ((inhibit-read-only t))
 149         (insert command "\n"))
 150       (if (and (not no-async) (fboundp 'start-process))
 151           (progn
 152             (setq proc (start-process "Diff" buf shell-file-name
 153                                       shell-command-switch command))
 154             (set-process-filter proc 'diff-process-filter)
 155             (set-process-sentinel
 156              proc (lambda (proc msg)
 157                     (with-current-buffer (process-buffer proc)
 158                       (diff-sentinel (process-exit-status proc))))))
 159         ;; Async processes aren't available.
 160         (let ((inhibit-read-only t))
 161           (diff-sentinel
 162            (call-process shell-file-name nil buf nil
 163                          shell-command-switch command)))))
 164     buf))
 165
 166 (defun diff-process-filter (proc string)
 167   (with-current-buffer (process-buffer proc)
 168     (let ((moving (= (point) (process-mark proc))))
 169       (save-excursion
 170         ;; Insert the text, advancing the process marker.
 171         (goto-char (process-mark proc))
 172         (let ((inhibit-read-only t))
 173           (insert string))
 174         (set-marker (process-mark proc) (point)))
 175       (if moving (goto-char (process-mark proc))))))
 176
 177 ;;;###autoload
 178 (defun diff-backup (file &optional switches)
 179   "Diff this file with its backup file or vice versa.
 180 Uses the latest backup, if there are several numerical backups.
 181 If this file is a backup, diff it with its original.
 182 The backup file is the first file given to `diff'.
 183 With prefix arg, prompt for diff switches."
 184   (interactive (list (read-file-name "Diff (file with backup): ")
 185                      (diff-switches)))
 186   (let (bak ori)
 187     (if (backup-file-name-p file)
 188         (setq bak file
 189               ori (file-name-sans-versions file))
 190       (setq bak (or (diff-latest-backup-file file)
 191                     (error "No backup found for %s" file))
 192             ori file))
 193     (diff bak ori switches)))
 194
 195 (defun diff-latest-backup-file (fn)     ; actually belongs into files.el
 196   "Return the latest existing backup of FILE, or nil."
 197   (let ((handler (find-file-name-handler fn 'diff-latest-backup-file)))
 198     (if handler
 199         (funcall handler 'diff-latest-backup-file fn)
 200       (file-newest-backup fn))))
 201
 202 (provide 'diff)
 203
 204 ;; arch-tag: 7de2c29b-7ea5-4b85-9b9d-72dd860de2bd
 205 ;;; diff.el ends here