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 ;;; This is duplicated in vc.el.
  34 (defvar diff-switches "-c"
  35   "*A string or list of strings specifying switches to be be passed to diff.")
  36
  37 (defvar diff-regexp-alist
  38   '(
  39     ;; -u format: @@ -OLDSTART,OLDEND +NEWSTART,NEWEND @@
  40     ("^@@ -\\([0-9]+\\),[0-9]+ \\+\\([0-9]+\\),[0-9]+ @@$" 1 2)
  41
  42     ;; -c format: *** OLDSTART,OLDEND ****
  43     ("^\\*\\*\\* \\([0-9]+\\),[0-9]+ \\*\\*\\*\\*$" 1 nil)
  44     ;;            --- NEWSTART,NEWEND ----
  45     ("^--- \\([0-9]+\\),[0-9]+ ----$" nil 1)
  46
  47     ;; plain diff format: OLDSTART[,OLDEND]{a,d,c}NEWSTART[,NEWEND]
  48     ("^\\([0-9]+\\)\\(,[0-9]+\\)?[adc]\\([0-9]+\\)\\(,[0-9]+\\)?$" 1 3)
  49
  50     ;; -e (ed) format: OLDSTART[,OLDEND]{a,d,c}
  51     ("^\\([0-9]+\\)\\(,[0-9]+\\)?[adc]$" 1)
  52
  53     ;; -f format: {a,d,c}OLDSTART[ OLDEND]
  54     ;; -n format: {a,d,c}OLDSTART LINES-CHANGED
  55     ("^[adc]\\([0-9]+\\)\\( [0-9]+\\)?$" 1)
  56     )
  57   "Alist (REGEXP OLD-IDX NEW-IDX) of regular expressions to match difference
  58 sections in \\[diff] output.  If REGEXP matches, the OLD-IDX'th
  59 subexpression gives the line number in the old file, and NEW-IDX'th
  60 subexpression gives the line number in the new file.  If OLD-IDX or NEW-IDX
  61 is nil, REGEXP matches only half a section.")
  62
  63 (defvar diff-old-file nil
  64   "This is the old file name in the comparison in this buffer.")
  65 (defvar diff-new-file nil
  66   "This is the new file name in the comparison in this buffer.")
  67 (defvar diff-old-temp-file nil
  68   "This is the name of a temp file to be deleted after diff finishes.")
  69 (defvar diff-new-temp-file nil
  70   "This is the name of a temp file to be deleted after diff finishes.")
  71
  72 ;; See compilation-parse-errors-function (compile.el).
  73 (defun diff-parse-differences (limit-search find-at-least)
  74   (setq compilation-error-list nil)
  75   (message "Parsing differences...")
  76
  77   ;; Don't reparse diffs already seen at last parse.
  78   (if compilation-parsing-end (goto-char compilation-parsing-end))
  79
  80   ;; Construct in REGEXP a regexp composed of all those in dired-regexp-alist.
  81   (let ((regexp (mapconcat (lambda (elt)
  82                              (concat "\\(" (car elt) "\\)"))
  83                            diff-regexp-alist
  84                            "\\|"))
  85         ;; (GROUP-IDX OLD-IDX NEW-IDX)
  86         (groups (let ((subexpr 1))
  87                   (mapcar (lambda (elt)
  88                             (prog1
  89                                 (cons subexpr
  90                                       (mapcar (lambda (n)
  91                                                 (and n
  92                                                      (+ subexpr n)))
  93                                               (cdr elt)))
  94                               (setq subexpr (+ subexpr 1
  95                                                (count-regexp-groupings
  96                                                 (car elt))))))
  97                           diff-regexp-alist)))
  98
  99         (new-error
 100          (function (lambda (file subexpr)
 101                      (setq compilation-error-list
 102                            (cons
 103                             (cons (save-excursion
 104                                     ;; Report location of message
 105                                     ;; at beginning of line.
 106                                     (goto-char
 107                                      (match-beginning subexpr))
 108                                     (beginning-of-line)
 109                                     (point-marker))
 110                                   ;; Report location of corresponding text.
 111                                   (let ((line (string-to-int
 112                                                (buffer-substring
 113                                                 (match-beginning subexpr)
 114                                                 (match-end subexpr)))))
 115                                     (save-excursion
 116                                       (set-buffer (find-file-noselect file))
 117                                       (save-excursion
 118                                         (goto-line line)
 119                                         (point-marker)))))
 120                             compilation-error-list)))))
 121
 122         (found-desired nil)
 123         (num-loci-found 0)
 124         g)
 125
 126     (while (and (not found-desired)
 127                 ;; We don't just pass LIMIT-SEARCH to re-search-forward
 128                 ;; because we want to find matches containing LIMIT-SEARCH
 129                 ;; but which extend past it.
 130                 (re-search-forward regexp nil t))
 131
 132       ;; Find which individual regexp matched.
 133       (setq g groups)
 134       (while (and g (null (match-beginning (car (car g)))))
 135         (setq g (cdr g)))
 136       (setq g (car g))
 137
 138       (if (nth 1 g)                     ;OLD-IDX
 139           (funcall new-error diff-old-file (nth 1 g)))
 140       (if (nth 2 g)                     ;NEW-IDX
 141           (funcall new-error diff-new-file (nth 2 g)))
 142
 143       (setq num-loci-found (1+ num-loci-found))
 144       (if (or (and find-at-least
 145                    (>= num-loci-found find-at-least))
 146               (and limit-search (>= (point) limit-search)))
 147               ;; We have found as many new loci as the user wants,
 148               ;; or the user wanted a specific diff, and we're past it.
 149           (setq found-desired t)))
 150     (if found-desired
 151         (setq compilation-parsing-end (point))
 152       ;; Set to point-max, not point, so we don't perpetually
 153       ;; parse the last bit of text when it isn't a diff header.
 154       (setq compilation-parsing-end (point-max)))
 155     (message "Parsing differences...done"))
 156   (setq compilation-error-list (nreverse compilation-error-list)))
 157
 158 ;;;###autoload
 159 (defun diff (old new &optional switches)
 160   "Find and display the differences between OLD and NEW files.
 161 Interactively the current buffer's file name is the default for for NEW
 162 and a backup file for NEW is the default for OLD.
 163 With prefix arg, prompt for diff switches."
 164   (interactive
 165    (nconc
 166     (let (oldf newf)
 167       (nreverse
 168        (list
 169         (setq newf (buffer-file-name)
 170               newf (if (and newf (file-exists-p newf))
 171                        (read-file-name
 172                         (concat "Diff new file: ("
 173                                 (file-name-nondirectory newf) ") ")
 174                         nil newf t)
 175                      (read-file-name "Diff new file: " nil nil t)))
 176         (setq oldf (file-newest-backup newf)
 177               oldf (if (and oldf (file-exists-p oldf))
 178                        (read-file-name
 179                         (concat "Diff original file: ("
 180                                 (file-name-nondirectory oldf) ") ")
 181                         (file-name-directory oldf) oldf t)
 182                      (read-file-name "Diff original file: "
 183                                      (file-name-directory newf) nil t))))))
 184     (if current-prefix-arg
 185         (list (read-string "Diff switches: "
 186                            (if (stringp diff-switches)
 187                                diff-switches
 188                              (mapconcat 'identity diff-switches " "))))
 189       nil)))
 190   (setq new (expand-file-name new)
 191         old (expand-file-name old))
 192   (let ((old-alt (file-local-copy old))
 193         (new-alt (file-local-copy new))
 194         buf)
 195     (unwind-protect
 196         (let ((command
 197                (mapconcat 'identity
 198                           (append '("diff")
 199                                   ;; Use explicitly specified switches
 200                                   (if switches
 201                                       (if (consp switches)
 202                                           switches (list switches))
 203                                     ;; If not specified, use default.
 204                                     (if (consp diff-switches)
 205                                         diff-switches
 206                                       (list diff-switches)))
 207                                   (if (or old-alt new-alt)
 208                                       (list "-L" old "-L" new))
 209                                   (list (or old-alt old))
 210                                   (list (or new-alt new)))
 211                           " ")))
 212           (setq buf
 213                 (compile-internal command
 214                                   "No more differences" "Diff"
 215                                   'diff-parse-differences))
 216           (save-excursion
 217             (set-buffer buf)
 218             (set (make-local-variable 'diff-old-file) old)
 219             (set (make-local-variable 'diff-new-file) new)
 220             (set (make-local-variable 'diff-old-temp-file) old-alt)
 221             (set (make-local-variable 'diff-new-temp-file) new-alt)
 222             (set (make-local-variable 'compilation-finish-function)
 223                  (function (lambda (buff msg)
 224                              (if diff-old-temp-file
 225                                  (delete-file diff-old-temp-file))
 226                              (if diff-new-temp-file
 227                                  (delete-file diff-new-temp-file))))))
 228           buf))))
 229
 230 ;;;###autoload
 231 (defun diff-backup (file &optional switches)
 232   "Diff this file with its backup file or vice versa.
 233 Uses the latest backup, if there are several numerical backups.
 234 If this file is a backup, diff it with its original.
 235 The backup file is the first file given to `diff'."
 236   (interactive (list (read-file-name "Diff (file with backup): ")
 237                      (if current-prefix-arg
 238                          (read-string "Diff switches: "
 239                                       (if (stringp diff-switches)
 240                                           diff-switches
 241                                         (mapconcat 'identity
 242                                                    diff-switches " ")))
 243                        nil)))
 244   (let (bak ori)
 245     (if (backup-file-name-p file)
 246         (setq bak file
 247               ori (file-name-sans-versions file))
 248       (setq bak (or (diff-latest-backup-file file)
 249                     (error "No backup found for %s" file))
 250             ori file))
 251     (diff bak ori switches)))
 252
 253 (defun diff-latest-backup-file (fn)     ; actually belongs into files.el
 254   "Return the latest existing backup of FILE, or nil."
 255   ;; First try simple backup, then the highest numbered of the
 256   ;; numbered backups.
 257   ;; Ignore the value of version-control because we look for existing
 258   ;; backups, which maybe were made earlier or by another user with
 259   ;; a different value of version-control.
 260   (setq fn (expand-file-name fn))
 261   (or
 262    (let ((bak (make-backup-file-name fn)))
 263      (if (file-exists-p bak) bak))
 264    (let* ((dir (file-name-directory fn))
 265           (base-versions (concat (file-name-nondirectory fn) ".~"))
 266           (bv-length (length base-versions)))
 267      (concat dir
 268              (car (sort
 269                    (file-name-all-completions base-versions dir)
 270                    ;; bv-length is a fluid var for backup-extract-version:
 271                    (function
 272                     (lambda (fn1 fn2)
 273                       (> (backup-extract-version fn1)
 274                          (backup-extract-version fn2))))))))))
 275
 276 (provide 'diff)
 277
 278 ;;; diff.el ends here