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b035a678 | 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 RS |
83 | ;; [various key definitions] |
84 | ;; | |
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 | ||
94 | ;; PUBLIC: define a new major mode which inherits from an existing one. | |
95 | ||
6ad50101 | 96 | ;;;###autoload |
06d35594 RS |
97 | (defmacro define-derived-mode (child parent name &optional docstring &rest body) |
98 | "Create a new mode as a variant of an existing mode. | |
76078cf0 RS |
99 | |
100 | The arguments to this command are as follow: | |
101 | ||
06d35594 | 102 | CHILD: the name of the command for the derived mode. |
04c817d4 DL |
103 | PARENT: the name of the command for the parent mode (e.g. `text-mode'). |
104 | NAME: a string which will appear in the status line (e.g. \"Hypertext\") | |
b72226e3 RS |
105 | DOCSTRING: an optional documentation string--if you do not supply one, |
106 | the function will attempt to invent something useful. | |
107 | BODY: forms to execute just before running the | |
76078cf0 RS |
108 | hooks for the new mode. |
109 | ||
06d35594 | 110 | Here is how you could define LaTeX-Thesis mode as a variant of LaTeX mode: |
76078cf0 | 111 | |
06d35594 | 112 | (define-derived-mode LaTeX-thesis-mode LaTeX-mode \"LaTeX-Thesis\") |
76078cf0 | 113 | |
b72226e3 RS |
114 | You could then make new key bindings for `LaTeX-thesis-mode-map' |
115 | without changing regular LaTeX mode. In this example, BODY is empty, | |
116 | and DOCSTRING is generated by default. | |
76078cf0 | 117 | |
04c817d4 | 118 | On a more complicated level, the following command uses `sgml-mode' as |
06d35594 | 119 | the parent, and then sets the variable `case-fold-search' to nil: |
76078cf0 | 120 | |
06d35594 | 121 | (define-derived-mode article-mode sgml-mode \"Article\" |
76078cf0 RS |
122 | \"Major mode for editing technical articles.\" |
123 | (setq case-fold-search nil)) | |
124 | ||
125 | Note that if the documentation string had been left out, it would have | |
126 | been generated automatically, with a reference to the keymap." | |
127 | ||
6ad50101 SM |
128 | (when (and docstring (not (stringp docstring))) |
129 | ;; Some trickiness, since what appears to be the docstring may really be | |
130 | ;; the first element of the body. | |
131 | (push docstring body) | |
132 | (setq docstring nil)) | |
133 | ||
134 | (unless parent (setq parent 'fundamental-mode)) | |
135 | ||
136 | (let ((map (derived-mode-map-name child)) | |
137 | (syntax (derived-mode-syntax-table-name child)) | |
138 | (abbrev (derived-mode-abbrev-table-name child)) | |
139 | (hook (derived-mode-hook-name child)) | |
140 | (docstring (derived-mode-make-docstring parent child docstring))) | |
141 | ||
142 | `(progn | |
143 | (defvar ,map (make-sparse-keymap)) | |
144 | (defvar ,syntax (make-char-table 'syntax-table nil)) | |
145 | (defvar ,abbrev) | |
146 | (define-abbrev-table ',abbrev nil) | |
147 | (put ',child 'derived-mode-parent ',parent) | |
148 | ||
149 | (defun ,child () | |
150 | ,docstring | |
151 | (interactive) | |
76078cf0 | 152 | ; Run the parent. |
b761da87 | 153 | ;; (combine-run-hooks |
6ad50101 SM |
154 | |
155 | (,parent) | |
76078cf0 | 156 | ; Identify special modes. |
6ad50101 SM |
157 | (if (get (quote ,parent) 'special) |
158 | (put (quote ,child) 'special t)) | |
76078cf0 | 159 | ; Identify the child mode. |
6ad50101 SM |
160 | (setq major-mode (quote ,child)) |
161 | (setq mode-name ,name) | |
76078cf0 | 162 | ; Set up maps and tables. |
6ad50101 SM |
163 | (unless (keymap-parent ,map) |
164 | (set-keymap-parent ,map (current-local-map))) | |
165 | (let ((parent (char-table-parent ,syntax))) | |
166 | (unless (and parent (not (eq parent (standard-syntax-table)))) | |
167 | (set-char-table-parent ,syntax (syntax-table)))) | |
168 | (when local-abbrev-table | |
169 | (mapatoms | |
170 | (lambda (symbol) | |
171 | (or (intern-soft (symbol-name symbol) ,abbrev) | |
172 | (define-abbrev ,abbrev (symbol-name symbol) | |
173 | (symbol-value symbol) (symbol-function symbol)))) | |
174 | local-abbrev-table)) | |
175 | ||
176 | (use-local-map ,map) | |
177 | (set-syntax-table ,syntax) | |
178 | (setq local-abbrev-table ,abbrev) | |
76078cf0 | 179 | ; Splice in the body (if any). |
b761da87 SM |
180 | ,@body |
181 | ;; ) | |
04c817d4 | 182 | ; Run the hooks, if any. |
6ad50101 SM |
183 | (run-hooks ',hook))))) |
184 | ||
185 | ;; PUBLIC: find if the current mode derives from another. | |
76078cf0 | 186 | |
6ad50101 SM |
187 | (defun derived-mode-p (&rest modes) |
188 | "Non-nil if the current major mode is derived from one of MODES. | |
189 | Uses the `derived-mode-parent' property of the symbol to trace backwards." | |
190 | (let ((parent major-mode)) | |
191 | (while (and (not (memq parent modes)) | |
192 | (setq parent (get parent 'derived-mode-parent)))) | |
193 | parent)) | |
76078cf0 | 194 | |
06d35594 | 195 | ;; PUBLIC: find the ultimate class of a derived mode. |
76078cf0 | 196 | |
06d35594 | 197 | (defun derived-mode-class (mode) |
04c817d4 | 198 | "Find the class of a major MODE. |
06d35594 | 199 | A mode's class is the first ancestor which is NOT a derived mode. |
6ad50101 SM |
200 | Use the `derived-mode-parent' property of the symbol to trace backwards. |
201 | Since major-modes might derive from each other and from `fundamental-mode', | |
202 | this function is not very useful. Use `derived-mode-p' instead." | |
06d35594 RS |
203 | (while (get mode 'derived-mode-parent) |
204 | (setq mode (get mode 'derived-mode-parent))) | |
76078cf0 RS |
205 | mode) |
206 | ||
207 | \f | |
6ad50101 | 208 | ;;; PRIVATE |
76078cf0 | 209 | |
e2154af9 RS |
210 | (defsubst derived-mode-hook-name (mode) |
211 | "Construct the mode hook name based on mode name MODE." | |
212 | (intern (concat (symbol-name mode) "-hook"))) | |
76078cf0 | 213 | |
06d35594 | 214 | (defsubst derived-mode-map-name (mode) |
04c817d4 | 215 | "Construct a map name based on a MODE name." |
76078cf0 RS |
216 | (intern (concat (symbol-name mode) "-map"))) |
217 | ||
06d35594 | 218 | (defsubst derived-mode-syntax-table-name (mode) |
04c817d4 | 219 | "Construct a syntax-table name based on a MODE name." |
76078cf0 RS |
220 | (intern (concat (symbol-name mode) "-syntax-table"))) |
221 | ||
06d35594 | 222 | (defsubst derived-mode-abbrev-table-name (mode) |
04c817d4 | 223 | "Construct an abbrev-table name based on a MODE name." |
76078cf0 RS |
224 | (intern (concat (symbol-name mode) "-abbrev-table"))) |
225 | ||
6ad50101 SM |
226 | (defun derived-mode-make-docstring (parent child &optional docstring) |
227 | "Construct a docstring for a new mode if none is provided." | |
228 | ||
229 | (let ((map (derived-mode-map-name child)) | |
230 | (syntax (derived-mode-syntax-table-name child)) | |
231 | (abbrev (derived-mode-abbrev-table-name child)) | |
232 | (hook (derived-mode-hook-name child))) | |
233 | ||
234 | (unless (stringp docstring) | |
235 | ;; Use a default docstring. | |
236 | (setq docstring | |
237 | (format "Major mode derived from `%s' by `define-derived-mode'. | |
238 | It inherits all of the parent's attributes, but has its own keymap, | |
239 | abbrev table and syntax table: | |
240 | ||
241 | `%s', `%s' and `%s' | |
242 | ||
243 | which more-or-less shadow %s's corresponding tables." | |
244 | parent map abbrev syntax parent))) | |
245 | ||
246 | (unless (string-match (regexp-quote (symbol-name hook)) docstring) | |
247 | ;; Make sure the docstring mentions the mode's hook | |
248 | (setq docstring | |
249 | (concat docstring | |
250 | (if (eq parent 'fundamental-mode) | |
251 | "\n\nThis mode " | |
252 | (concat | |
253 | "\n\nIn addition to any hooks its parent mode " | |
254 | (if (string-match (regexp-quote (format "`%s'" parent)) | |
255 | docstring) nil | |
256 | (format "`%s' " parent)) | |
257 | "might have run,\nthis mode ")) | |
258 | (format "runs the hook `%s'" hook) | |
259 | ", as the final step\nduring initialization."))) | |
260 | ||
261 | (unless (string-match "\\\\[{[]" docstring) | |
262 | ;; And don't forget to put the mode's keymap | |
263 | (setq docstring (concat docstring "\n\n\\{" (symbol-name map) "}"))) | |
264 | ||
265 | docstring)) | |
266 | ||
267 | \f | |
268 | ;;; OBSOLETE | |
269 | ;; The functions below are only provided for backward compatibility with | |
270 | ;; code byte-compiled with versions of derived.el prior to Emacs-21. | |
271 | ||
272 | (defsubst derived-mode-setup-function-name (mode) | |
273 | "Construct a setup-function name based on a MODE name." | |
274 | (intern (concat (symbol-name mode) "-setup"))) | |
275 | ||
76078cf0 | 276 | \f |
06d35594 | 277 | ;; Utility functions for defining a derived mode. |
76078cf0 | 278 | |
ec830850 | 279 | ;;;###autoload |
06d35594 | 280 | (defun derived-mode-init-mode-variables (mode) |
04c817d4 | 281 | "Initialise variables for a new MODE. |
26757b4b RS |
282 | Right now, if they don't already exist, set up a blank keymap, an |
283 | empty syntax table, and an empty abbrev table -- these will be merged | |
284 | the first time the mode is used." | |
285 | ||
06d35594 | 286 | (if (boundp (derived-mode-map-name mode)) |
26757b4b | 287 | t |
04c817d4 | 288 | (eval `(defvar ,(derived-mode-map-name mode) |
26757b4b | 289 | (make-sparse-keymap) |
04c817d4 | 290 | ,(format "Keymap for %s." mode))) |
06d35594 | 291 | (put (derived-mode-map-name mode) 'derived-mode-unmerged t)) |
26757b4b | 292 | |
06d35594 | 293 | (if (boundp (derived-mode-syntax-table-name mode)) |
26757b4b | 294 | t |
04c817d4 DL |
295 | (eval `(defvar ,(derived-mode-syntax-table-name mode) |
296 | ;; Make a syntax table which doesn't specify anything | |
297 | ;; for any char. Valid data will be merged in by | |
298 | ;; derived-mode-merge-syntax-tables. | |
299 | (make-char-table 'syntax-table nil) | |
300 | ,(format "Syntax table for %s." mode))) | |
06d35594 | 301 | (put (derived-mode-syntax-table-name mode) 'derived-mode-unmerged t)) |
26757b4b | 302 | |
06d35594 | 303 | (if (boundp (derived-mode-abbrev-table-name mode)) |
26757b4b | 304 | t |
04c817d4 DL |
305 | (eval `(defvar ,(derived-mode-abbrev-table-name mode) |
306 | (progn | |
307 | (define-abbrev-table (derived-mode-abbrev-table-name mode) nil) | |
308 | (make-abbrev-table)) | |
309 | ,(format "Abbrev table for %s." mode))))) | |
76078cf0 | 310 | \f |
06d35594 | 311 | ;; Utility functions for running a derived mode. |
76078cf0 | 312 | |
06d35594 | 313 | (defun derived-mode-set-keymap (mode) |
04c817d4 | 314 | "Set the keymap of the new MODE, maybe merging with the parent." |
06d35594 | 315 | (let* ((map-name (derived-mode-map-name mode)) |
76078cf0 RS |
316 | (new-map (eval map-name)) |
317 | (old-map (current-local-map))) | |
f34e6918 RS |
318 | (and old-map |
319 | (get map-name 'derived-mode-unmerged) | |
320 | (derived-mode-merge-keymaps old-map new-map)) | |
06d35594 | 321 | (put map-name 'derived-mode-unmerged nil) |
26757b4b | 322 | (use-local-map new-map))) |
76078cf0 | 323 | |
04c817d4 DL |
324 | (defun derived-mode-set-syntax-table (mode) |
325 | "Set the syntax table of the new MODE, maybe merging with the parent." | |
06d35594 | 326 | (let* ((table-name (derived-mode-syntax-table-name mode)) |
76078cf0 RS |
327 | (old-table (syntax-table)) |
328 | (new-table (eval table-name))) | |
06d35594 RS |
329 | (if (get table-name 'derived-mode-unmerged) |
330 | (derived-mode-merge-syntax-tables old-table new-table)) | |
331 | (put table-name 'derived-mode-unmerged nil) | |
26757b4b | 332 | (set-syntax-table new-table))) |
76078cf0 | 333 | |
06d35594 | 334 | (defun derived-mode-set-abbrev-table (mode) |
04c817d4 | 335 | "Set the abbrev table for MODE if it exists. |
26757b4b | 336 | Always merge its parent into it, since the merge is non-destructive." |
06d35594 | 337 | (let* ((table-name (derived-mode-abbrev-table-name mode)) |
26757b4b RS |
338 | (old-table local-abbrev-table) |
339 | (new-table (eval table-name))) | |
06d35594 | 340 | (derived-mode-merge-abbrev-tables old-table new-table) |
26757b4b | 341 | (setq local-abbrev-table new-table))) |
76078cf0 | 342 | |
06d35594 | 343 | ;;;(defun derived-mode-run-setup-function (mode) |
b72226e3 | 344 | ;;; "Run the setup function if it exists." |
76078cf0 | 345 | |
06d35594 | 346 | ;;; (let ((fname (derived-mode-setup-function-name mode))) |
b72226e3 RS |
347 | ;;; (if (fboundp fname) |
348 | ;;; (funcall fname)))) | |
76078cf0 | 349 | |
06d35594 | 350 | (defun derived-mode-run-hooks (mode) |
e2154af9 | 351 | "Run the mode hook for MODE." |
e2154af9 | 352 | (let ((hooks-name (derived-mode-hook-name mode))) |
76078cf0 RS |
353 | (if (boundp hooks-name) |
354 | (run-hooks hooks-name)))) | |
355 | ||
356 | ;; Functions to merge maps and tables. | |
357 | ||
06d35594 | 358 | (defun derived-mode-merge-keymaps (old new) |
04c817d4 | 359 | "Merge an OLD keymap into a NEW one. |
37a4f4b6 | 360 | The old keymap is set to be the last cdr of the new one, so that there will |
76078cf0 | 361 | be automatic inheritance." |
04c817d4 | 362 | ;; ?? Can this just use `set-keymap-parent'? |
37a4f4b6 RS |
363 | (let ((tail new)) |
364 | ;; Scan the NEW map for prefix keys. | |
365 | (while (consp tail) | |
366 | (and (consp (car tail)) | |
367 | (let* ((key (vector (car (car tail)))) | |
368 | (subnew (lookup-key new key)) | |
369 | (subold (lookup-key old key))) | |
370 | ;; If KEY is a prefix key in both OLD and NEW, merge them. | |
371 | (and (keymapp subnew) (keymapp subold) | |
372 | (derived-mode-merge-keymaps subold subnew)))) | |
373 | (and (vectorp (car tail)) | |
374 | ;; Search a vector of ASCII char bindings for prefix keys. | |
375 | (let ((i (1- (length (car tail))))) | |
376 | (while (>= i 0) | |
377 | (let* ((key (vector i)) | |
378 | (subnew (lookup-key new key)) | |
379 | (subold (lookup-key old key))) | |
380 | ;; If KEY is a prefix key in both OLD and NEW, merge them. | |
381 | (and (keymapp subnew) (keymapp subold) | |
382 | (derived-mode-merge-keymaps subold subnew))) | |
383 | (setq i (1- i))))) | |
384 | (setq tail (cdr tail)))) | |
26757b4b | 385 | (setcdr (nthcdr (1- (length new)) new) old)) |
76078cf0 | 386 | |
06d35594 | 387 | (defun derived-mode-merge-syntax-tables (old new) |
04c817d4 | 388 | "Merge an OLD syntax table into a NEW one. |
76078cf0 | 389 | Where the new table already has an entry, nothing is copied from the old one." |
5dee7dae | 390 | (set-char-table-parent new old)) |
26757b4b | 391 | |
56152e17 RS |
392 | ;; Merge an old abbrev table into a new one. |
393 | ;; This function requires internal knowledge of how abbrev tables work, | |
394 | ;; presuming that they are obarrays with the abbrev as the symbol, the expansion | |
395 | ;; as the value of the symbol, and the hook as the function definition. | |
06d35594 | 396 | (defun derived-mode-merge-abbrev-tables (old new) |
56152e17 | 397 | (if old |
04c817d4 DL |
398 | (mapatoms |
399 | (lambda (symbol) | |
400 | (or (intern-soft (symbol-name symbol) new) | |
401 | (define-abbrev new (symbol-name symbol) | |
402 | (symbol-value symbol) (symbol-function symbol)))) | |
56152e17 | 403 | old))) |
76078cf0 | 404 | |
06d35594 | 405 | (provide 'derived) |
26757b4b | 406 | |
06d35594 | 407 | ;;; derived.el ends here |