summaryrefslogtreecommitdiff
path: root/lisp/diff.el
blob: 7b92c6a4314da7512137da71ad2b75d120711b38 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
;; "DIFF" mode for handling output from unix diff utility.
;; Copyright (C) 1990 Free Software Foundation, Inc.
;; Written fpb@ittc.wec.com 1/27/89

;; This file is part of GNU Emacs.

;; GNU Emacs is free software; you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation; either version 1, or (at your option)
;; any later version.

;; GNU Emacs is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;; GNU General Public License for more details.

;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs; see the file COPYING.  If not, write to
;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.

;; todo: diff-switches flexibility:
;; (defconst diff-switches-function
;;   '(lambda (file)
;;     (if (string-match "\\.el$" file)
;; 	 "-c -F\"^(\""
;;       "-p"))
;;  "Function to return switches to pass to the `diff' utility, in \\[diff].
;; This function is called with one arg, a file name, and returns a string
;; containing 0 or more arguments which are passed on to `diff'.
;; NOTE: This is not an ordinary hook; it may not be a list of functions.")

;;  - fpb@ittc.wec.com - Sep 25, 1990
;; Added code to support sccs diffing.
;; also fixed one minor glitch in the
;; search for the pattern.  If you only 1 addition you won't find the end
;; of the pattern (minor)

;;
(defvar diff-switches nil
  "*A list of switches to pass to the diff program.")

(defvar diff-search-pattern "^\\([0-9]\\|\\*\\*\\*\\*\\*\\*\\*\\*\\*\\*\\*\\*\\*\\*\\*\\)"
  "Regular expression that delineates difference regions in diffs.")

(defvar diff-rcs-extension ",v"
  "*Extension to find RCS file, some systems do not use ,v")

;; Initialize the keymap if it isn't already
(if (boundp 'diff-mode-map)
    nil
  (setq diff-mode-map (make-keymap))
  (suppress-keymap diff-mode-map)
  (define-key diff-mode-map "?" 'describe-mode)
  (define-key diff-mode-map "." 'diff-beginning-of-diff)
  (define-key diff-mode-map " " 'scroll-up)
  (define-key diff-mode-map "\177" 'scroll-down)
  (define-key diff-mode-map "n" 'diff-next-difference)
  (define-key diff-mode-map "p" 'diff-previous-difference)
  (define-key diff-mode-map "j" 'diff-show-difference))

;;;###autoload
(defun diff (old new)
  "Find and display the differences between OLD and NEW files.
Interactively you are prompted with the current buffer's file name for NEW
and what appears to be it's backup for OLD."
  (interactive
   (let (oldf newf)
     (reverse
      (list
       (setq newf (buffer-file-name)
	     newf (if (and newf (file-exists-p newf))
			  (read-file-name
			   (concat "Diff new file: ("
				   (file-name-nondirectory newf) ") ")
			   nil newf t)
			(read-file-name "Diff new file: " nil nil t)))
       (setq oldf (file-newest-backup newf)
	     oldf (if (and oldf (file-exists-p oldf))
			  (read-file-name
			   (concat "Diff original file: ("
				   (file-name-nondirectory oldf) ") ")
			   (file-name-directory oldf) oldf t)
			(read-file-name "Diff original file: "
					(file-name-directory newf) nil t)))))))
  (message "Comparing files %s %s..." new old)
  (setq new (expand-file-name new)
	old (expand-file-name old))
  (diff-internal-diff "diff" (append diff-switches (list new old)) nil))

(defun diff-sccs (new)
  "Find and display the differences between OLD and SCCS files."
  (interactive
   (let (newf)
      (list
       (setq newf (buffer-file-name)
	     newf (if (and newf (file-exists-p newf))
			  (read-file-name
			   (concat "Diff new file: ("
				   (file-name-nondirectory newf) ") ")
			   nil newf t)
			(read-file-name "Diff new file: " nil nil t))))))

  (message "Comparing SCCS file %s..." new)
  (setq new (expand-file-name new))
  (if (file-exists-p (concat
		      (file-name-directory new)
		      "SCCS/s."
		      (file-name-nondirectory new)))
      (diff-internal-diff "sccs"
			  (append '("diffs") diff-switches (list new))
			  2)
    (error "%s does not exist"
	   (concat (file-name-directory new) "SCCS/s."
		   (file-name-nondirectory new)))))

(defun diff-rcs (new)
  "Find and display the differences between OLD and RCS files."
  (interactive
   (let (newf)
      (list
       (setq newf (buffer-file-name)
	     newf (if (and newf (file-exists-p newf))
			  (read-file-name
			   (concat "Diff new file: ("
				   (file-name-nondirectory newf) ") ")
			   nil newf t)
			(read-file-name "Diff new file: " nil nil t))))))

  (message "Comparing RCS file %s..." new)
  (let* ((fullname (expand-file-name new))
       (rcsfile (concat (file-name-directory fullname)
                       "RCS/"
                       (file-name-nondirectory fullname)
                       diff-rcs-extension)))
    (if (file-exists-p rcsfile)
      (diff-internal-diff "rcsdiff" (append diff-switches (list fullname)) 4)
      (error "%s does not exist" rcsfile))))

(defun diff-internal-diff (diff-command sw strip)
  (let ((buffer-read-only nil))
    (with-output-to-temp-buffer "*Diff Output*"
      (buffer-disable-undo standard-output)
      (save-excursion
	(set-buffer standard-output)
	(erase-buffer)
	(apply 'call-process diff-command nil t nil sw)))
    (set-buffer "*Diff Output*")
    (goto-char (point-min))
    (while sw
      (if (string= (car sw) "-c")
	  ;; strip leading filenames from context diffs
	  (progn (forward-line 2) (delete-region (point-min) (point))))
      (if (and (string= (car sw) "-C") (string= "sccs" diff-command))
	  ;; strip stuff from SCCS context diffs
	  (progn (forward-line 2) (delete-region (point-min) (point))))
      (setq sw (cdr sw)))
    (if strip
	;; strip stuff from SCCS context diffs
	(progn (forward-line strip) (delete-region (point-min) (point)))))
  (diff-mode)
  (if (string= "0" diff-total-differences)
      (let ((buffer-read-only nil))
	(insert (message "There are no differences.")))
    (narrow-to-region (point) (progn
				(forward-line 1)
				(if (re-search-forward diff-search-pattern
						       nil t)
				    (goto-char (match-beginning 0))
				  (goto-char (point-max)))))
    (setq diff-current-difference "1")))

;; Take a buffer full of Unix diff output and go into a mode to easily
;; see the next and previous difference
(defun diff-mode ()
  "Diff Mode is used by \\[diff] for perusing the output from the diff program.
All normal editing commands are turned off.  Instead, these are available:
\\<diff-mode-map>
\\[diff-beginning-of-diff]	Move point to start of this difference.
\\[scroll-up]	Scroll to next screen of this difference.
\\[scroll-down]	Scroll to previous screen of this difference.
\\[diff-next-difference]	Move to Next Difference.
\\[diff-previous-difference]	Move to Previous Difference.
\\[diff-show-difference]	Jump to difference specified by numeric position.
"
  (interactive)
  (use-local-map diff-mode-map)
  (setq buffer-read-only t
	major-mode 'diff-mode
	mode-name "Diff"
	mode-line-modified "--- "
	mode-line-process
	'(" " diff-current-difference "/" diff-total-differences))
  (make-local-variable 'diff-current-difference)
  (set (make-local-variable 'diff-total-differences)
       (int-to-string (diff-count-differences))))

(defun diff-next-difference (n)
  "Go to the beginning of the next difference.
Differences are delimited by `diff-search-pattern'."
  (interactive "p")
  (if (< n 0) (diff-previous-difference (- n))
    (if (zerop n) ()
      (goto-char (point-min))
      (forward-line 1) ; to get past the match for the start of this diff
      (widen)
      (if (re-search-forward diff-search-pattern nil 'move n)
	  (let ((start (goto-char (match-beginning 0))))
	    (forward-line 1)
	    (if (re-search-forward diff-search-pattern nil 'move)
		(goto-char (match-beginning 0)))
	    (narrow-to-region start (point))
	    (setq diff-current-difference
		  (int-to-string (+ n (string-to-int
				       diff-current-difference)))))
	(re-search-backward diff-search-pattern nil)
	(narrow-to-region (point) (point-max))
	(message "No following differences.")
	(setq diff-current-difference diff-total-differences))
      (goto-char (point-min)))))

(defun diff-previous-difference (n)
  "Go the the beginning of the previous difference.
Differences are delimited by `diff-search-pattern'."
  (interactive "p")
  (if (< n 0) (diff-next-difference (- n))
    (if (zerop n) ()
      (goto-char (point-min))
      (widen)
      (if (re-search-backward diff-search-pattern nil 'move n)
	  (setq diff-current-difference
		(int-to-string (- (string-to-int diff-current-difference) n)))
	(message "No previous differences.")
	(setq diff-current-difference "1"))
      (narrow-to-region (point) (progn
				  (forward-line 1)
				  (re-search-forward diff-search-pattern nil)
				  (goto-char (match-beginning 0))))
      (goto-char (point-min)))))

(defun diff-show-difference (n)
  "Show difference number N (prefix argument)."
  (interactive "p")
  (let ((cur (string-to-int diff-current-difference)))
    (cond ((or (= n cur)
	       (zerop n)
	       (not (natnump n))) ; should signal an error perhaps.
	   ;; just redisplay.
	   (goto-char (point-min)))
	  ((< n cur)
	   (diff-previous-difference (- cur n)))
	  ((> n cur)
	   (diff-next-difference (- n cur))))))

(defun diff-beginning-of-diff ()
  "Go to beginning of current difference."
  (interactive)
  (goto-char (point-min)))

;; This function counts up the number of differences in the buffer.
(defun diff-count-differences ()
  "Count number of differences in the current buffer."
  (message "Counting differences...")
  (save-excursion
    (save-restriction
      (widen)
      (goto-char (point-min))
      (let ((cnt 0))
	(while (re-search-forward diff-search-pattern nil t)
	  (setq cnt (1+ cnt)))
	(message "Counting differences...done (%d)" cnt)
	cnt))))