lisp/diff.el

   1 ;;; diff.el --- Run `diff' in compilation-mode.
   2
   3 ;; Copyright (C) 1992 Free Software Foundation, Inc.
   4
   5 ;; Keywords: unix, tools
   6
   7 ;; This file is part of GNU Emacs.
   8
   9 ;; GNU Emacs is free software; you can redistribute it and/or modify
  10 ;; it under the terms of the GNU General Public License as published by
  11 ;; the Free Software Foundation; either version 2, or (at your option)
  12 ;; any later version.
  13
  14 ;; GNU Emacs is distributed in the hope that it will be useful,
  15 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  16 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17 ;; GNU General Public License for more details.
  18
  19 ;; You should have received a copy of the GNU General Public License
  20 ;; along with GNU Emacs; see the file COPYING.  If not, write to
  21 ;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
  22
  23 ;;; Commentary:
  24
  25 ;; This package helps you explore differences between files, using the
  26 ;; UNIX command diff(1).  The commands are `diff' and `diff-backup'.
  27 ;; You can specify options with `diff-switches'.
  28
  29 ;;; Code:
  30
  31 (require 'compile)
  32
  33 (defvar diff-switches "-c"
  34   "*A string or list of strings specifying switches to be be passed to diff.")
  35
  36 (defvar diff-regexp-alist
  37   '(
  38     ;; -u format: @@ -OLDSTART,OLDEND +NEWSTART,NEWEND @@
  39     ("^@@ -\\([0-9]+\\),[0-9]+ \\+\\([0-9]+\\),[0-9]+ @@$" 1 2)
  40
  41     ;; -c format: *** OLDSTART,OLDEND ****
  42     ("^\\*\\*\\* \\([0-9]+\\),[0-9]+ \\*\\*\\*\\*$" 1 nil)
  43     ;;            --- NEWSTART,NEWEND ----
  44     ("^--- \\([0-9]+\\),[0-9]+ ----$" nil 1)
  45
  46     ;; plain diff format: OLDSTART[,OLDEND]{a,d,c}NEWSTART[,NEWEND]
  47     ("^\\([0-9]+\\)\\(,[0-9]+\\)?[adc]\\([0-9]+\\)\\(,[0-9]+\\)?$" 1 3)
  48
  49     ;; -e (ed) format: OLDSTART[,OLDEND]{a,d,c}
  50     ("^\\([0-9]+\\)\\(,[0-9]+\\)?[adc]$" 1)
  51
  52     ;; -f format: {a,d,c}OLDSTART[ OLDEND]
  53     ;; -n format: {a,d,c}OLDSTART LINES-CHANGED
  54     ("^[adc]\\([0-9]+\\)\\( [0-9]+\\)?$" 1)
  55     )
  56   "Alist (REGEXP OLD-IDX NEW-IDX) of regular expressions to match difference
  57 sections in \\[diff] output.  If REGEXP matches, the OLD-IDX'th
  58 subexpression gives the line number in the old file, and NEW-IDX'th
  59 subexpression gives the line number in the new file.  If OLD-IDX or NEW-IDX
  60 is nil, REGEXP matches only half a section.")
  61
  62 (defvar diff-old-file nil
  63   "This is the old file name in the comparison in this buffer.")
  64 (defvar diff-new-file nil
  65   "This is the new file name in the comparison in this buffer.")
  66 (defvar diff-old-temp-file nil
  67   "This is the name of a temp file to be deleted after diff finishes.")
  68 (defvar diff-new-temp-file nil
  69   "This is the name of a temp file to be deleted after diff finishes.")
  70
  71 ;; See compilation-parse-errors-function (compile.el).
  72 (defun diff-parse-differences (limit-search find-at-least)
  73   (setq compilation-error-list nil)
  74   (message "Parsing differences...")
  75
  76   ;; Don't reparse diffs already seen at last parse.
  77   (goto-char compilation-parsing-end)
  78
  79   ;; Construct in REGEXP a regexp composed of all those in dired-regexp-alist.
  80   (let ((regexp (mapconcat (lambda (elt)
  81                              (concat "\\(" (car elt) "\\)"))
  82                            diff-regexp-alist
  83                            "\\|"))
  84         ;; (GROUP-IDX OLD-IDX NEW-IDX)
  85         (groups (let ((subexpr 1))
  86                   (mapcar (lambda (elt)
  87                             (prog1
  88                                 (cons subexpr
  89                                       (mapcar (lambda (n)
  90                                                 (and n
  91                                                      (+ subexpr n)))
  92                                               (cdr elt)))
  93                               (setq subexpr (+ subexpr 1
  94                                                (count-regexp-groupings
  95                                                 (car elt))))))
  96                           diff-regexp-alist)))
  97
  98         (new-error
  99          (function (lambda (file subexpr)
 100                      (setq compilation-error-list
 101                            (cons
 102                             (cons (save-excursion
 103                                     ;; Report location of message
 104                                     ;; at beginning of line.
 105                                     (goto-char
 106                                      (match-beginning subexpr))
 107                                     (beginning-of-line)
 108                                     (point-marker))
 109                                   ;; Report location of corresponding text.
 110                                   (let ((line (string-to-int
 111                                                (buffer-substring
 112                                                 (match-beginning subexpr)
 113                                                 (match-end subexpr)))))
 114                                     (save-excursion
 115                                       (set-buffer (find-file-noselect file))
 116                                       (save-excursion
 117                                         (goto-line line)
 118                                         (point-marker)))))
 119                             compilation-error-list)))))
 120
 121         (found-desired nil)
 122         (num-loci-found 0)
 123         g)
 124
 125     (while (and (not found-desired)
 126                 ;; We don't just pass LIMIT-SEARCH to re-search-forward
 127                 ;; because we want to find matches containing LIMIT-SEARCH
 128                 ;; but which extend past it.
 129                 (re-search-forward regexp nil t))
 130
 131       ;; Find which individual regexp matched.
 132       (setq g groups)
 133       (while (and g (null (match-beginning (car (car g)))))
 134         (setq g (cdr g)))
 135       (setq g (car g))
 136
 137       (if (nth 1 g)                     ;OLD-IDX
 138           (funcall new-error diff-old-file (nth 1 g)))
 139       (if (nth 2 g)                     ;NEW-IDX
 140           (funcall new-error diff-new-file (nth 2 g)))
 141
 142       (setq num-loci-found (1+ num-loci-found))
 143       (if (or (and find-at-least
 144                    (>= num-loci-found find-at-least))
 145               (and limit-search (>= (point) limit-search)))
 146               ;; We have found as many new loci as the user wants,
 147               ;; or the user wanted a specific diff, and we're past it.
 148           (setq found-desired t)))
 149     (if found-desired
 150         (setq compilation-parsing-end (point))
 151       ;; Set to point-max, not point, so we don't perpetually
 152       ;; parse the last bit of text when it isn't a diff header.
 153       (setq compilation-parsing-end (point-max)))
 154     (message "Parsing differences...done"))
 155   (setq compilation-error-list (nreverse compilation-error-list)))
 156
 157 ;;;###autoload
 158 (defun diff (old new &optional switches)
 159   "Find and display the differences between OLD and NEW files.
 160 Interactively the current buffer's file name is the default for for NEW
 161 and a backup file for NEW is the default for OLD.
 162 With prefix arg, prompt for diff switches."
 163   (interactive
 164    (nconc
 165     (let (oldf newf)
 166       (nreverse
 167        (list
 168         (setq newf (buffer-file-name)
 169               newf (if (and newf (file-exists-p newf))
 170                        (read-file-name
 171                         (concat "Diff new file: ("
 172                                 (file-name-nondirectory newf) ") ")
 173                         nil newf t)
 174                      (read-file-name "Diff new file: " nil nil t)))
 175         (setq oldf (file-newest-backup newf)
 176               oldf (if (and oldf (file-exists-p oldf))
 177                        (read-file-name
 178                         (concat "Diff original file: ("
 179                                 (file-name-nondirectory oldf) ") ")
 180                         (file-name-directory oldf) oldf t)
 181                      (read-file-name "Diff original file: "
 182                                      (file-name-directory newf) nil t))))))
 183     (if current-prefix-arg
 184         (list (read-string "Diff switches: "
 185                            (if (stringp diff-switches)
 186                                diff-switches
 187                              (mapconcat 'identity diff-switches " "))))
 188       nil)))
 189   (setq new (expand-file-name new)
 190         old (expand-file-name old))
 191   (let ((old-alt (file-local-copy old))
 192         (new-alt (file-local-copy new))
 193         buf)
 194     (unwind-protect
 195         (let ((command
 196                (mapconcat 'identity
 197                           (append '("diff")
 198                                   (if (consp diff-switches)
 199                                       diff-switches
 200                                     (list diff-switches))
 201                                   (if (or old-alt new-alt)
 202                                       (list "-L" old "-L" new))
 203                                   (list (or old-alt old))
 204                                   (list (or new-alt new)))
 205                           " ")))
 206           (setq buf
 207                 (compile-internal command
 208                                   "No more differences" "Diff"
 209                                   'diff-parse-differences))
 210           (save-excursion
 211             (set-buffer buf)
 212             (set (make-local-variable 'diff-old-file) old)
 213             (set (make-local-variable 'diff-new-file) new)
 214             (set (make-local-variable 'diff-old-temp-file) old-alt)
 215             (set (make-local-variable 'diff-new-temp-file) new-alt)
 216             (set (make-local-variable 'compilation-finish-function)
 217                  (function (lambda (buff msg)
 218                              (if diff-old-temp-file
 219                                  (delete-file diff-old-temp-file))
 220                              (if diff-new-temp-file
 221                                  (delete-file diff-new-temp-file))))))
 222           buf))))
 223
 224 ;;;###autoload
 225 (defun diff-backup (file &optional switches)
 226   "Diff this file with its backup file or vice versa.
 227 Uses the latest backup, if there are several numerical backups.
 228 If this file is a backup, diff it with its original.
 229 The backup file is the first file given to `diff'."
 230   (interactive (list (read-file-name "Diff (file with backup): ")
 231                      (if current-prefix-arg
 232                          (read-string "Diff switches: "
 233                                       (if (stringp diff-switches)
 234                                           diff-switches
 235                                         (mapconcat 'identity
 236                                                    diff-switches " ")))
 237                        nil)))
 238   (let (bak ori)
 239     (if (backup-file-name-p file)
 240         (setq bak file
 241               ori (file-name-sans-versions file))
 242       (setq bak (or (diff-latest-backup-file file)
 243                     (error "No backup found for %s" file))
 244             ori file))
 245     (diff bak ori switches)))
 246
 247 (defun diff-latest-backup-file (fn)     ; actually belongs into files.el
 248   "Return the latest existing backup of FILE, or nil."
 249   ;; First try simple backup, then the highest numbered of the
 250   ;; numbered backups.
 251   ;; Ignore the value of version-control because we look for existing
 252   ;; backups, which maybe were made earlier or by another user with
 253   ;; a different value of version-control.
 254   (setq fn (expand-file-name fn))
 255   (or
 256    (let ((bak (make-backup-file-name fn)))
 257      (if (file-exists-p bak) bak))
 258    (let* ((dir (file-name-directory fn))
 259           (base-versions (concat (file-name-nondirectory fn) ".~"))
 260           (bv-length (length base-versions)))
 261      (concat dir
 262              (car (sort
 263                    (file-name-all-completions base-versions dir)
 264                    ;; bv-length is a fluid var for backup-extract-version:
 265                    (function
 266                     (lambda (fn1 fn2)
 267                       (> (backup-extract-version fn1)
 268                          (backup-extract-version fn2))))))))))
 269
 270 ;;; diff.el ends here