Commit | Line | Data |
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55535639 | 1 | ;;; derived.el --- allow inheritance of major modes |
06d35594 | 2 | ;;; (formerly mode-clone.el) |
76078cf0 | 3 | |
04c817d4 | 4 | ;; Copyright (C) 1993, 1994, 1999 Free Software Foundation, Inc. |
76078cf0 RS |
5 | |
6 | ;; Author: David Megginson (dmeggins@aix1.uottawa.ca) | |
26757b4b | 7 | ;; Maintainer: FSF |
6ad50101 | 8 | ;; Keywords: extensions |
76078cf0 RS |
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 2, or (at your option) | |
15 | ;; 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 | |
b578f267 EN |
23 | ;; along with GNU Emacs; see the file COPYING. If not, write to the |
24 | ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330, | |
25 | ;; Boston, MA 02111-1307, USA. | |
76078cf0 RS |
26 | \f |
27 | ;;; Commentary: | |
28 | ||
29 | ;; GNU Emacs is already, in a sense, object oriented -- each object | |
30 | ;; (buffer) belongs to a class (major mode), and that class defines | |
31 | ;; the relationship between messages (input events) and methods | |
32 | ;; (commands) by means of a keymap. | |
33 | ;; | |
34 | ;; The only thing missing is a good scheme of inheritance. It is | |
35 | ;; possible to simulate a single level of inheritance with generous | |
36 | ;; use of hooks and a bit of work -- sgml-mode, for example, also runs | |
37 | ;; the hooks for text-mode, and keymaps can inherit from other keymaps | |
38 | ;; -- but generally, each major mode ends up reinventing the wheel. | |
39 | ;; Ideally, someone should redesign all of Emacs's major modes to | |
40 | ;; follow a more conventional object-oriented system: when defining a | |
41 | ;; new major mode, the user should need only to name the existing mode | |
42 | ;; it is most similar to, then list the (few) differences. | |
43 | ;; | |
44 | ;; In the mean time, this package offers most of the advantages of | |
b72226e3 | 45 | ;; full inheritance with the existing major modes. The macro |
06d35594 | 46 | ;; `define-derived-mode' allows the user to make a variant of an existing |
76078cf0 RS |
47 | ;; major mode, with its own keymap. The new mode will inherit the key |
48 | ;; bindings of its parent, and will, in fact, run its parent first | |
49 | ;; every time it is called. For example, the commands | |
50 | ;; | |
06d35594 | 51 | ;; (define-derived-mode hypertext-mode text-mode "Hypertext" |
76078cf0 RS |
52 | ;; "Major mode for hypertext.\n\n\\{hypertext-mode-map}" |
53 | ;; (setq case-fold-search nil)) | |
54 | ;; | |
55 | ;; (define-key hypertext-mode-map [down-mouse-3] 'do-hyper-link) | |
56 | ;; | |
57 | ;; will create a function `hypertext-mode' with its own (sparse) | |
58 | ;; keymap `hypertext-mode-map.' The command M-x hypertext-mode will | |
59 | ;; perform the following actions: | |
60 | ;; | |
61 | ;; - run the command (text-mode) to get its default setup | |
62 | ;; - replace the current keymap with 'hypertext-mode-map,' which will | |
63 | ;; inherit from 'text-mode-map'. | |
64 | ;; - replace the current syntax table with | |
65 | ;; 'hypertext-mode-syntax-table', which will borrow its defaults | |
66 | ;; from the current text-mode-syntax-table. | |
26757b4b RS |
67 | ;; - replace the current abbrev table with |
68 | ;; 'hypertext-mode-abbrev-table', which will borrow its defaults | |
69 | ;; from the current text-mode-abbrev table | |
76078cf0 RS |
70 | ;; - change the mode line to read "Hypertext" |
71 | ;; - assign the value 'hypertext-mode' to the 'major-mode' variable | |
72 | ;; - run the body of commands provided in the macro -- in this case, | |
73 | ;; set the local variable `case-fold-search' to nil. | |
76078cf0 RS |
74 | ;; |
75 | ;; The advantages of this system are threefold. First, text mode is | |
76 | ;; untouched -- if you had added the new keystroke to `text-mode-map,' | |
77 | ;; possibly using hooks, you would have added it to all text buffers | |
78 | ;; -- here, it appears only in hypertext buffers, where it makes | |
06d35594 RS |
79 | ;; sense. Second, it is possible to build even further, and make |
80 | ;; a derived mode from a derived mode. The commands | |
76078cf0 | 81 | ;; |
06d35594 | 82 | ;; (define-derived-mode html-mode hypertext-mode "HTML") |
76078cf0 | 83 | ;; [various key definitions] |
4fb0e558 | 84 | ;; |
76078cf0 RS |
85 | ;; will add a new major mode for HTML with very little fuss. |
86 | ;; | |
6ad50101 SM |
87 | ;; Note also the function `derived-mode-p' which can tell if the current |
88 | ;; mode derives from another. In a hypertext-mode, buffer, for example, | |
89 | ;; (derived-mode-p 'text-mode) would return non-nil. This should always | |
90 | ;; be used in place of (eq major-mode 'text-mode). | |
76078cf0 RS |
91 | \f |
92 | ;;; Code: | |
93 | ||
4fb0e558 SS |
94 | ;;; PRIVATE: defsubst must be defined before they are first used |
95 | ||
96 | (defsubst derived-mode-hook-name (mode) | |
97 | "Construct the mode hook name based on mode name MODE." | |
98 | (intern (concat (symbol-name mode) "-hook"))) | |
99 | ||
100 | (defsubst derived-mode-map-name (mode) | |
101 | "Construct a map name based on a MODE name." | |
102 | (intern (concat (symbol-name mode) "-map"))) | |
103 | ||
104 | (defsubst derived-mode-syntax-table-name (mode) | |
105 | "Construct a syntax-table name based on a MODE name." | |
106 | (intern (concat (symbol-name mode) "-syntax-table"))) | |
107 | ||
108 | (defsubst derived-mode-abbrev-table-name (mode) | |
109 | "Construct an abbrev-table name based on a MODE name." | |
110 | (intern (concat (symbol-name mode) "-abbrev-table"))) | |
111 | ||
76078cf0 RS |
112 | ;; PUBLIC: define a new major mode which inherits from an existing one. |
113 | ||
6ad50101 | 114 | ;;;###autoload |
06d35594 RS |
115 | (defmacro define-derived-mode (child parent name &optional docstring &rest body) |
116 | "Create a new mode as a variant of an existing mode. | |
76078cf0 RS |
117 | |
118 | The arguments to this command are as follow: | |
119 | ||
06d35594 | 120 | CHILD: the name of the command for the derived mode. |
3848aeeb GM |
121 | PARENT: the name of the command for the parent mode (e.g. `text-mode') |
122 | or nil if there is no parent. | |
04c817d4 | 123 | NAME: a string which will appear in the status line (e.g. \"Hypertext\") |
b72226e3 RS |
124 | DOCSTRING: an optional documentation string--if you do not supply one, |
125 | the function will attempt to invent something useful. | |
126 | BODY: forms to execute just before running the | |
4c82860a | 127 | hooks for the new mode. Do not use `interactive' here. |
76078cf0 | 128 | |
06d35594 | 129 | Here is how you could define LaTeX-Thesis mode as a variant of LaTeX mode: |
76078cf0 | 130 | |
06d35594 | 131 | (define-derived-mode LaTeX-thesis-mode LaTeX-mode \"LaTeX-Thesis\") |
76078cf0 | 132 | |
b72226e3 RS |
133 | You could then make new key bindings for `LaTeX-thesis-mode-map' |
134 | without changing regular LaTeX mode. In this example, BODY is empty, | |
135 | and DOCSTRING is generated by default. | |
76078cf0 | 136 | |
04c817d4 | 137 | On a more complicated level, the following command uses `sgml-mode' as |
06d35594 | 138 | the parent, and then sets the variable `case-fold-search' to nil: |
76078cf0 | 139 | |
06d35594 | 140 | (define-derived-mode article-mode sgml-mode \"Article\" |
76078cf0 RS |
141 | \"Major mode for editing technical articles.\" |
142 | (setq case-fold-search nil)) | |
143 | ||
144 | Note that if the documentation string had been left out, it would have | |
145 | been generated automatically, with a reference to the keymap." | |
146 | ||
6ad50101 SM |
147 | (when (and docstring (not (stringp docstring))) |
148 | ;; Some trickiness, since what appears to be the docstring may really be | |
149 | ;; the first element of the body. | |
150 | (push docstring body) | |
151 | (setq docstring nil)) | |
152 | ||
3848aeeb | 153 | (when (eq parent 'fundamental-mode) (setq parent nil)) |
6ad50101 SM |
154 | |
155 | (let ((map (derived-mode-map-name child)) | |
156 | (syntax (derived-mode-syntax-table-name child)) | |
157 | (abbrev (derived-mode-abbrev-table-name child)) | |
158 | (hook (derived-mode-hook-name child)) | |
159 | (docstring (derived-mode-make-docstring parent child docstring))) | |
4fb0e558 | 160 | |
6ad50101 SM |
161 | `(progn |
162 | (defvar ,map (make-sparse-keymap)) | |
3848aeeb | 163 | (defvar ,syntax (make-syntax-table)) |
b6b7eda9 SM |
164 | (defvar ,abbrev |
165 | (progn (define-abbrev-table ',abbrev nil) ,abbrev)) | |
6ad50101 | 166 | (put ',child 'derived-mode-parent ',parent) |
4fb0e558 | 167 | |
6ad50101 SM |
168 | (defun ,child () |
169 | ,docstring | |
170 | (interactive) | |
76078cf0 | 171 | ; Run the parent. |
d6cf8a24 | 172 | (delay-mode-hooks |
6ad50101 | 173 | |
3848aeeb | 174 | (,(or parent 'kill-all-local-variables)) |
76078cf0 | 175 | ; Identify the child mode. |
6ad50101 SM |
176 | (setq major-mode (quote ,child)) |
177 | (setq mode-name ,name) | |
3848aeeb GM |
178 | ; Identify special modes. |
179 | ,(when parent | |
180 | `(progn | |
181 | (if (get (quote ,parent) 'special) | |
182 | (put (quote ,child) 'special t)) | |
76078cf0 | 183 | ; Set up maps and tables. |
3848aeeb GM |
184 | (unless (keymap-parent ,map) |
185 | (set-keymap-parent ,map (current-local-map))) | |
186 | (let ((parent (char-table-parent ,syntax))) | |
187 | (unless (and parent (not (eq parent (standard-syntax-table)))) | |
188 | (set-char-table-parent ,syntax (syntax-table)))) | |
189 | (when local-abbrev-table | |
190 | (mapatoms | |
191 | (lambda (symbol) | |
192 | (or (intern-soft (symbol-name symbol) ,abbrev) | |
193 | (define-abbrev ,abbrev (symbol-name symbol) | |
194 | (symbol-value symbol) (symbol-function symbol)))) | |
195 | local-abbrev-table)))) | |
4fb0e558 | 196 | |
6ad50101 SM |
197 | (use-local-map ,map) |
198 | (set-syntax-table ,syntax) | |
199 | (setq local-abbrev-table ,abbrev) | |
76078cf0 | 200 | ; Splice in the body (if any). |
b761da87 | 201 | ,@body |
d6cf8a24 | 202 | ) |
04c817d4 | 203 | ; Run the hooks, if any. |
d6cf8a24 | 204 | (run-mode-hooks ',hook))))) |
6ad50101 | 205 | |
06d35594 | 206 | ;; PUBLIC: find the ultimate class of a derived mode. |
76078cf0 | 207 | |
06d35594 | 208 | (defun derived-mode-class (mode) |
04c817d4 | 209 | "Find the class of a major MODE. |
06d35594 | 210 | A mode's class is the first ancestor which is NOT a derived mode. |
6ad50101 SM |
211 | Use the `derived-mode-parent' property of the symbol to trace backwards. |
212 | Since major-modes might derive from each other and from `fundamental-mode', | |
213 | this function is not very useful. Use `derived-mode-p' instead." | |
06d35594 RS |
214 | (while (get mode 'derived-mode-parent) |
215 | (setq mode (get mode 'derived-mode-parent))) | |
76078cf0 RS |
216 | mode) |
217 | ||
218 | \f | |
6ad50101 | 219 | ;;; PRIVATE |
76078cf0 | 220 | |
6ad50101 SM |
221 | (defun derived-mode-make-docstring (parent child &optional docstring) |
222 | "Construct a docstring for a new mode if none is provided." | |
223 | ||
224 | (let ((map (derived-mode-map-name child)) | |
225 | (syntax (derived-mode-syntax-table-name child)) | |
226 | (abbrev (derived-mode-abbrev-table-name child)) | |
227 | (hook (derived-mode-hook-name child))) | |
228 | ||
229 | (unless (stringp docstring) | |
230 | ;; Use a default docstring. | |
231 | (setq docstring | |
3848aeeb GM |
232 | (if (null parent) |
233 | (format "Major-mode. | |
234 | Uses keymap `%s', abbrev table `%s' and syntax-table `%s'." map abbrev syntax) | |
235 | (format "Major mode derived from `%s' by `define-derived-mode'. | |
6ad50101 SM |
236 | It inherits all of the parent's attributes, but has its own keymap, |
237 | abbrev table and syntax table: | |
238 | ||
239 | `%s', `%s' and `%s' | |
240 | ||
241 | which more-or-less shadow %s's corresponding tables." | |
3848aeeb | 242 | parent map abbrev syntax parent)))) |
4fb0e558 | 243 | |
6ad50101 SM |
244 | (unless (string-match (regexp-quote (symbol-name hook)) docstring) |
245 | ;; Make sure the docstring mentions the mode's hook | |
246 | (setq docstring | |
247 | (concat docstring | |
3848aeeb | 248 | (if (null parent) |
6ad50101 SM |
249 | "\n\nThis mode " |
250 | (concat | |
251 | "\n\nIn addition to any hooks its parent mode " | |
252 | (if (string-match (regexp-quote (format "`%s'" parent)) | |
253 | docstring) nil | |
254 | (format "`%s' " parent)) | |
255 | "might have run,\nthis mode ")) | |
256 | (format "runs the hook `%s'" hook) | |
257 | ", as the final step\nduring initialization."))) | |
4fb0e558 | 258 | |
6ad50101 SM |
259 | (unless (string-match "\\\\[{[]" docstring) |
260 | ;; And don't forget to put the mode's keymap | |
261 | (setq docstring (concat docstring "\n\n\\{" (symbol-name map) "}"))) | |
262 | ||
263 | docstring)) | |
264 | ||
265 | \f | |
266 | ;;; OBSOLETE | |
267 | ;; The functions below are only provided for backward compatibility with | |
268 | ;; code byte-compiled with versions of derived.el prior to Emacs-21. | |
269 | ||
270 | (defsubst derived-mode-setup-function-name (mode) | |
271 | "Construct a setup-function name based on a MODE name." | |
272 | (intern (concat (symbol-name mode) "-setup"))) | |
273 | ||
76078cf0 | 274 | \f |
06d35594 | 275 | ;; Utility functions for defining a derived mode. |
76078cf0 | 276 | |
ec830850 | 277 | ;;;###autoload |
06d35594 | 278 | (defun derived-mode-init-mode-variables (mode) |
04c817d4 | 279 | "Initialise variables for a new MODE. |
26757b4b RS |
280 | Right now, if they don't already exist, set up a blank keymap, an |
281 | empty syntax table, and an empty abbrev table -- these will be merged | |
282 | the first time the mode is used." | |
283 | ||
06d35594 | 284 | (if (boundp (derived-mode-map-name mode)) |
26757b4b | 285 | t |
04c817d4 | 286 | (eval `(defvar ,(derived-mode-map-name mode) |
26757b4b | 287 | (make-sparse-keymap) |
04c817d4 | 288 | ,(format "Keymap for %s." mode))) |
06d35594 | 289 | (put (derived-mode-map-name mode) 'derived-mode-unmerged t)) |
26757b4b | 290 | |
06d35594 | 291 | (if (boundp (derived-mode-syntax-table-name mode)) |
26757b4b | 292 | t |
04c817d4 DL |
293 | (eval `(defvar ,(derived-mode-syntax-table-name mode) |
294 | ;; Make a syntax table which doesn't specify anything | |
295 | ;; for any char. Valid data will be merged in by | |
296 | ;; derived-mode-merge-syntax-tables. | |
297 | (make-char-table 'syntax-table nil) | |
298 | ,(format "Syntax table for %s." mode))) | |
06d35594 | 299 | (put (derived-mode-syntax-table-name mode) 'derived-mode-unmerged t)) |
26757b4b | 300 | |
06d35594 | 301 | (if (boundp (derived-mode-abbrev-table-name mode)) |
26757b4b | 302 | t |
04c817d4 DL |
303 | (eval `(defvar ,(derived-mode-abbrev-table-name mode) |
304 | (progn | |
305 | (define-abbrev-table (derived-mode-abbrev-table-name mode) nil) | |
306 | (make-abbrev-table)) | |
307 | ,(format "Abbrev table for %s." mode))))) | |
76078cf0 | 308 | \f |
06d35594 | 309 | ;; Utility functions for running a derived mode. |
76078cf0 | 310 | |
06d35594 | 311 | (defun derived-mode-set-keymap (mode) |
04c817d4 | 312 | "Set the keymap of the new MODE, maybe merging with the parent." |
06d35594 | 313 | (let* ((map-name (derived-mode-map-name mode)) |
76078cf0 RS |
314 | (new-map (eval map-name)) |
315 | (old-map (current-local-map))) | |
f34e6918 RS |
316 | (and old-map |
317 | (get map-name 'derived-mode-unmerged) | |
318 | (derived-mode-merge-keymaps old-map new-map)) | |
06d35594 | 319 | (put map-name 'derived-mode-unmerged nil) |
26757b4b | 320 | (use-local-map new-map))) |
76078cf0 | 321 | |
04c817d4 DL |
322 | (defun derived-mode-set-syntax-table (mode) |
323 | "Set the syntax table of the new MODE, maybe merging with the parent." | |
06d35594 | 324 | (let* ((table-name (derived-mode-syntax-table-name mode)) |
76078cf0 RS |
325 | (old-table (syntax-table)) |
326 | (new-table (eval table-name))) | |
06d35594 RS |
327 | (if (get table-name 'derived-mode-unmerged) |
328 | (derived-mode-merge-syntax-tables old-table new-table)) | |
329 | (put table-name 'derived-mode-unmerged nil) | |
26757b4b | 330 | (set-syntax-table new-table))) |
76078cf0 | 331 | |
06d35594 | 332 | (defun derived-mode-set-abbrev-table (mode) |
04c817d4 | 333 | "Set the abbrev table for MODE if it exists. |
26757b4b | 334 | Always merge its parent into it, since the merge is non-destructive." |
06d35594 | 335 | (let* ((table-name (derived-mode-abbrev-table-name mode)) |
26757b4b RS |
336 | (old-table local-abbrev-table) |
337 | (new-table (eval table-name))) | |
06d35594 | 338 | (derived-mode-merge-abbrev-tables old-table new-table) |
26757b4b | 339 | (setq local-abbrev-table new-table))) |
76078cf0 | 340 | |
06d35594 | 341 | ;;;(defun derived-mode-run-setup-function (mode) |
b72226e3 | 342 | ;;; "Run the setup function if it exists." |
76078cf0 | 343 | |
06d35594 | 344 | ;;; (let ((fname (derived-mode-setup-function-name mode))) |
b72226e3 RS |
345 | ;;; (if (fboundp fname) |
346 | ;;; (funcall fname)))) | |
76078cf0 | 347 | |
06d35594 | 348 | (defun derived-mode-run-hooks (mode) |
e2154af9 | 349 | "Run the mode hook for MODE." |
e2154af9 | 350 | (let ((hooks-name (derived-mode-hook-name mode))) |
76078cf0 RS |
351 | (if (boundp hooks-name) |
352 | (run-hooks hooks-name)))) | |
353 | ||
354 | ;; Functions to merge maps and tables. | |
355 | ||
06d35594 | 356 | (defun derived-mode-merge-keymaps (old new) |
04c817d4 | 357 | "Merge an OLD keymap into a NEW one. |
37a4f4b6 | 358 | The old keymap is set to be the last cdr of the new one, so that there will |
76078cf0 | 359 | be automatic inheritance." |
04c817d4 | 360 | ;; ?? Can this just use `set-keymap-parent'? |
37a4f4b6 RS |
361 | (let ((tail new)) |
362 | ;; Scan the NEW map for prefix keys. | |
363 | (while (consp tail) | |
364 | (and (consp (car tail)) | |
365 | (let* ((key (vector (car (car tail)))) | |
366 | (subnew (lookup-key new key)) | |
367 | (subold (lookup-key old key))) | |
368 | ;; If KEY is a prefix key in both OLD and NEW, merge them. | |
369 | (and (keymapp subnew) (keymapp subold) | |
370 | (derived-mode-merge-keymaps subold subnew)))) | |
371 | (and (vectorp (car tail)) | |
372 | ;; Search a vector of ASCII char bindings for prefix keys. | |
373 | (let ((i (1- (length (car tail))))) | |
374 | (while (>= i 0) | |
375 | (let* ((key (vector i)) | |
376 | (subnew (lookup-key new key)) | |
377 | (subold (lookup-key old key))) | |
378 | ;; If KEY is a prefix key in both OLD and NEW, merge them. | |
379 | (and (keymapp subnew) (keymapp subold) | |
380 | (derived-mode-merge-keymaps subold subnew))) | |
381 | (setq i (1- i))))) | |
382 | (setq tail (cdr tail)))) | |
26757b4b | 383 | (setcdr (nthcdr (1- (length new)) new) old)) |
76078cf0 | 384 | |
06d35594 | 385 | (defun derived-mode-merge-syntax-tables (old new) |
04c817d4 | 386 | "Merge an OLD syntax table into a NEW one. |
76078cf0 | 387 | Where the new table already has an entry, nothing is copied from the old one." |
5dee7dae | 388 | (set-char-table-parent new old)) |
26757b4b | 389 | |
56152e17 RS |
390 | ;; Merge an old abbrev table into a new one. |
391 | ;; This function requires internal knowledge of how abbrev tables work, | |
392 | ;; presuming that they are obarrays with the abbrev as the symbol, the expansion | |
393 | ;; as the value of the symbol, and the hook as the function definition. | |
06d35594 | 394 | (defun derived-mode-merge-abbrev-tables (old new) |
56152e17 | 395 | (if old |
04c817d4 DL |
396 | (mapatoms |
397 | (lambda (symbol) | |
398 | (or (intern-soft (symbol-name symbol) new) | |
399 | (define-abbrev new (symbol-name symbol) | |
400 | (symbol-value symbol) (symbol-function symbol)))) | |
56152e17 | 401 | old))) |
4fb0e558 | 402 | |
06d35594 | 403 | (provide 'derived) |
26757b4b | 404 | |
06d35594 | 405 | ;;; derived.el ends here |