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5e046f6d | 1 | ;;; derived.el --- allow inheritance of major modes |
84ae4908 | 2 | ;; (formerly mode-clone.el) |
5e046f6d | 3 | |
d59c3137 | 4 | ;; Copyright (C) 1993, 1994, 1999, 2001, 2002, 2003, 2004, |
f0fa15c5 | 5 | ;; 2005, 2006, 2007 Free Software Foundation, Inc. |
5e046f6d JB |
6 | |
7 | ;; Author: David Megginson (dmeggins@aix1.uottawa.ca) | |
8 | ;; Maintainer: FSF | |
9 | ;; Keywords: extensions | |
10 | ||
11 | ;; This file is part of GNU Emacs. | |
12 | ||
13 | ;; GNU Emacs is free software; you can redistribute it and/or modify | |
14 | ;; it under the terms of the GNU General Public License as published by | |
15 | ;; the Free Software Foundation; either version 2, or (at your option) | |
16 | ;; any later version. | |
17 | ||
18 | ;; GNU Emacs is distributed in the hope that it will be useful, | |
19 | ;; but WITHOUT ANY WARRANTY; without even the implied warranty of | |
20 | ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
21 | ;; GNU General Public License for more details. | |
22 | ||
23 | ;; You should have received a copy of the GNU General Public License | |
24 | ;; along with GNU Emacs; see the file COPYING. If not, write to the | |
3a35cf56 LK |
25 | ;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, |
26 | ;; Boston, MA 02110-1301, USA. | |
5e046f6d JB |
27 | \f |
28 | ;;; Commentary: | |
29 | ||
30 | ;; GNU Emacs is already, in a sense, object oriented -- each object | |
31 | ;; (buffer) belongs to a class (major mode), and that class defines | |
32 | ;; the relationship between messages (input events) and methods | |
33 | ;; (commands) by means of a keymap. | |
34 | ;; | |
35 | ;; The only thing missing is a good scheme of inheritance. It is | |
36 | ;; possible to simulate a single level of inheritance with generous | |
37 | ;; use of hooks and a bit of work -- sgml-mode, for example, also runs | |
38 | ;; the hooks for text-mode, and keymaps can inherit from other keymaps | |
39 | ;; -- but generally, each major mode ends up reinventing the wheel. | |
40 | ;; Ideally, someone should redesign all of Emacs's major modes to | |
41 | ;; follow a more conventional object-oriented system: when defining a | |
42 | ;; new major mode, the user should need only to name the existing mode | |
43 | ;; it is most similar to, then list the (few) differences. | |
44 | ;; | |
45 | ;; In the mean time, this package offers most of the advantages of | |
46 | ;; full inheritance with the existing major modes. The macro | |
47 | ;; `define-derived-mode' allows the user to make a variant of an existing | |
48 | ;; major mode, with its own keymap. The new mode will inherit the key | |
49 | ;; bindings of its parent, and will, in fact, run its parent first | |
50 | ;; every time it is called. For example, the commands | |
51 | ;; | |
52 | ;; (define-derived-mode hypertext-mode text-mode "Hypertext" | |
53 | ;; "Major mode for hypertext.\n\n\\{hypertext-mode-map}" | |
54 | ;; (setq case-fold-search nil)) | |
55 | ;; | |
56 | ;; (define-key hypertext-mode-map [down-mouse-3] 'do-hyper-link) | |
57 | ;; | |
58 | ;; will create a function `hypertext-mode' with its own (sparse) | |
59 | ;; keymap `hypertext-mode-map.' The command M-x hypertext-mode will | |
60 | ;; perform the following actions: | |
61 | ;; | |
62 | ;; - run the command (text-mode) to get its default setup | |
63 | ;; - replace the current keymap with 'hypertext-mode-map,' which will | |
64 | ;; inherit from 'text-mode-map'. | |
65 | ;; - replace the current syntax table with | |
66 | ;; 'hypertext-mode-syntax-table', which will borrow its defaults | |
67 | ;; from the current text-mode-syntax-table. | |
68 | ;; - replace the current abbrev table with | |
69 | ;; 'hypertext-mode-abbrev-table', which will borrow its defaults | |
70 | ;; from the current text-mode-abbrev table | |
71 | ;; - change the mode line to read "Hypertext" | |
72 | ;; - assign the value 'hypertext-mode' to the 'major-mode' variable | |
73 | ;; - run the body of commands provided in the macro -- in this case, | |
74 | ;; set the local variable `case-fold-search' to nil. | |
75 | ;; | |
76 | ;; The advantages of this system are threefold. First, text mode is | |
77 | ;; untouched -- if you had added the new keystroke to `text-mode-map,' | |
78 | ;; possibly using hooks, you would have added it to all text buffers | |
79 | ;; -- here, it appears only in hypertext buffers, where it makes | |
80 | ;; sense. Second, it is possible to build even further, and make | |
81 | ;; a derived mode from a derived mode. The commands | |
82 | ;; | |
83 | ;; (define-derived-mode html-mode hypertext-mode "HTML") | |
84 | ;; [various key definitions] | |
85 | ;; | |
86 | ;; will add a new major mode for HTML with very little fuss. | |
87 | ;; | |
88 | ;; Note also the function `derived-mode-p' which can tell if the current | |
89 | ;; mode derives from another. In a hypertext-mode, buffer, for example, | |
90 | ;; (derived-mode-p 'text-mode) would return non-nil. This should always | |
91 | ;; be used in place of (eq major-mode 'text-mode). | |
92 | \f | |
93 | ;;; Code: | |
94 | ||
95 | (eval-when-compile (require 'cl)) | |
96 | ||
97 | ;;; PRIVATE: defsubst must be defined before they are first used | |
98 | ||
99 | (defsubst derived-mode-hook-name (mode) | |
fea34e9f | 100 | "Construct a mode-hook name based on a MODE name." |
5e046f6d JB |
101 | (intern (concat (symbol-name mode) "-hook"))) |
102 | ||
103 | (defsubst derived-mode-map-name (mode) | |
104 | "Construct a map name based on a MODE name." | |
105 | (intern (concat (symbol-name mode) "-map"))) | |
106 | ||
107 | (defsubst derived-mode-syntax-table-name (mode) | |
108 | "Construct a syntax-table name based on a MODE name." | |
109 | (intern (concat (symbol-name mode) "-syntax-table"))) | |
110 | ||
111 | (defsubst derived-mode-abbrev-table-name (mode) | |
112 | "Construct an abbrev-table name based on a MODE name." | |
113 | (intern (concat (symbol-name mode) "-abbrev-table"))) | |
114 | ||
115 | ;; PUBLIC: define a new major mode which inherits from an existing one. | |
116 | ||
117 | ;;;###autoload | |
118 | (defmacro define-derived-mode (child parent name &optional docstring &rest body) | |
119 | "Create a new mode as a variant of an existing mode. | |
120 | ||
121 | The arguments to this command are as follow: | |
122 | ||
123 | CHILD: the name of the command for the derived mode. | |
124 | PARENT: the name of the command for the parent mode (e.g. `text-mode') | |
125 | or nil if there is no parent. | |
126 | NAME: a string which will appear in the status line (e.g. \"Hypertext\") | |
127 | DOCSTRING: an optional documentation string--if you do not supply one, | |
128 | the function will attempt to invent something useful. | |
129 | BODY: forms to execute just before running the | |
130 | hooks for the new mode. Do not use `interactive' here. | |
131 | ||
132 | BODY can start with a bunch of keyword arguments. The following keyword | |
133 | arguments are currently understood: | |
134 | :group GROUP | |
135 | Declare the customization group that corresponds to this mode. | |
3e2c3ab0 | 136 | The command `customize-mode' uses this. |
5e046f6d JB |
137 | :syntax-table TABLE |
138 | Use TABLE instead of the default. | |
139 | A nil value means to simply use the same syntax-table as the parent. | |
140 | :abbrev-table TABLE | |
141 | Use TABLE instead of the default. | |
142 | A nil value means to simply use the same abbrev-table as the parent. | |
143 | ||
144 | Here is how you could define LaTeX-Thesis mode as a variant of LaTeX mode: | |
145 | ||
146 | (define-derived-mode LaTeX-thesis-mode LaTeX-mode \"LaTeX-Thesis\") | |
147 | ||
148 | You could then make new key bindings for `LaTeX-thesis-mode-map' | |
149 | without changing regular LaTeX mode. In this example, BODY is empty, | |
150 | and DOCSTRING is generated by default. | |
151 | ||
152 | On a more complicated level, the following command uses `sgml-mode' as | |
153 | the parent, and then sets the variable `case-fold-search' to nil: | |
154 | ||
155 | (define-derived-mode article-mode sgml-mode \"Article\" | |
156 | \"Major mode for editing technical articles.\" | |
157 | (setq case-fold-search nil)) | |
158 | ||
159 | Note that if the documentation string had been left out, it would have | |
8d11b450 GM |
160 | been generated automatically, with a reference to the keymap. |
161 | ||
162 | The new mode runs the hook constructed by the function | |
a5079d40 LT |
163 | `derived-mode-hook-name'. |
164 | ||
165 | See Info node `(elisp)Derived Modes' for more details." | |
5e046f6d JB |
166 | (declare (debug (&define name symbolp sexp [&optional stringp] |
167 | [&rest keywordp sexp] def-body))) | |
168 | ||
169 | (when (and docstring (not (stringp docstring))) | |
170 | ;; Some trickiness, since what appears to be the docstring may really be | |
171 | ;; the first element of the body. | |
172 | (push docstring body) | |
173 | (setq docstring nil)) | |
174 | ||
175 | (when (eq parent 'fundamental-mode) (setq parent nil)) | |
176 | ||
177 | (let ((map (derived-mode-map-name child)) | |
178 | (syntax (derived-mode-syntax-table-name child)) | |
179 | (abbrev (derived-mode-abbrev-table-name child)) | |
180 | (declare-abbrev t) | |
181 | (declare-syntax t) | |
182 | (hook (derived-mode-hook-name child)) | |
183 | (group nil)) | |
184 | ||
185 | ;; Process the keyword args. | |
186 | (while (keywordp (car body)) | |
187 | (case (pop body) | |
188 | (:group (setq group (pop body))) | |
189 | (:abbrev-table (setq abbrev (pop body)) (setq declare-abbrev nil)) | |
190 | (:syntax-table (setq syntax (pop body)) (setq declare-syntax nil)) | |
191 | (t (pop body)))) | |
192 | ||
193 | (setq docstring (derived-mode-make-docstring | |
194 | parent child docstring syntax abbrev)) | |
195 | ||
196 | `(progn | |
156680e2 LT |
197 | (unless (get ',hook 'variable-documentation) |
198 | (put ',hook 'variable-documentation | |
199 | ,(format "Hook run when entering %s mode. | |
200 | No problems result if this variable is not bound. | |
201 | `add-hook' automatically binds it. (This is true for all hook variables.)" | |
202 | name))) | |
cc793355 JL |
203 | (unless (boundp ',map) |
204 | (put ',map 'definition-name ',child)) | |
5e046f6d JB |
205 | (defvar ,map (make-sparse-keymap)) |
206 | ,(if declare-syntax | |
cc793355 JL |
207 | `(progn |
208 | (unless (boundp ',syntax) | |
209 | (put ',syntax 'definition-name ',child)) | |
210 | (defvar ,syntax (make-syntax-table)))) | |
5e046f6d | 211 | ,(if declare-abbrev |
cc793355 JL |
212 | `(progn |
213 | (put ',abbrev 'definition-name ',child) | |
214 | (defvar ,abbrev | |
215 | (progn (define-abbrev-table ',abbrev nil) ,abbrev)))) | |
5e046f6d JB |
216 | (put ',child 'derived-mode-parent ',parent) |
217 | ,(if group `(put ',child 'custom-mode-group ,group)) | |
218 | ||
219 | (defun ,child () | |
220 | ,docstring | |
221 | (interactive) | |
222 | ; Run the parent. | |
223 | (delay-mode-hooks | |
224 | ||
225 | (,(or parent 'kill-all-local-variables)) | |
226 | ; Identify the child mode. | |
227 | (setq major-mode (quote ,child)) | |
228 | (setq mode-name ,name) | |
229 | ; Identify special modes. | |
230 | ,(when parent | |
231 | `(progn | |
232 | (if (get (quote ,parent) 'mode-class) | |
233 | (put (quote ,child) 'mode-class | |
234 | (get (quote ,parent) 'mode-class))) | |
235 | ; Set up maps and tables. | |
236 | (unless (keymap-parent ,map) | |
84ae4908 SM |
237 | ;; It would probably be better to set the keymap's parent |
238 | ;; at the toplevel rather than inside the mode function, | |
239 | ;; but this is not easy for at least the following reasons: | |
240 | ;; - the parent (and its keymap) may not yet be loaded. | |
241 | ;; - the parent's keymap name may be called something else | |
242 | ;; than <parent>-mode-map. | |
5e046f6d JB |
243 | (set-keymap-parent ,map (current-local-map))) |
244 | ,(when declare-syntax | |
245 | `(let ((parent (char-table-parent ,syntax))) | |
246 | (unless (and parent | |
247 | (not (eq parent (standard-syntax-table)))) | |
248 | (set-char-table-parent ,syntax (syntax-table))))))) | |
249 | ||
250 | (use-local-map ,map) | |
251 | ,(when syntax `(set-syntax-table ,syntax)) | |
252 | ,(when abbrev `(setq local-abbrev-table ,abbrev)) | |
253 | ; Splice in the body (if any). | |
254 | ,@body | |
255 | ) | |
256 | ;; Run the hooks, if any. | |
cdcfbcb2 | 257 | (run-mode-hooks ',hook))))) |
5e046f6d JB |
258 | |
259 | ;; PUBLIC: find the ultimate class of a derived mode. | |
260 | ||
261 | (defun derived-mode-class (mode) | |
262 | "Find the class of a major MODE. | |
263 | A mode's class is the first ancestor which is NOT a derived mode. | |
264 | Use the `derived-mode-parent' property of the symbol to trace backwards. | |
265 | Since major-modes might all derive from `fundamental-mode', this function | |
266 | is not very useful." | |
267 | (while (get mode 'derived-mode-parent) | |
268 | (setq mode (get mode 'derived-mode-parent))) | |
269 | mode) | |
bf247b6e | 270 | (make-obsolete 'derived-mode-class 'derived-mode-p "22.1") |
5e046f6d JB |
271 | |
272 | \f | |
273 | ;;; PRIVATE | |
274 | ||
275 | (defun derived-mode-make-docstring (parent child &optional | |
276 | docstring syntax abbrev) | |
277 | "Construct a docstring for a new mode if none is provided." | |
278 | ||
279 | (let ((map (derived-mode-map-name child)) | |
280 | (hook (derived-mode-hook-name child))) | |
281 | ||
282 | (unless (stringp docstring) | |
283 | ;; Use a default docstring. | |
284 | (setq docstring | |
285 | (if (null parent) | |
286 | (format "Major-mode. | |
287 | Uses keymap `%s', abbrev table `%s' and syntax-table `%s'." map abbrev syntax) | |
288 | (format "Major mode derived from `%s' by `define-derived-mode'. | |
289 | It inherits all of the parent's attributes, but has its own keymap, | |
290 | abbrev table and syntax table: | |
291 | ||
292 | `%s', `%s' and `%s' | |
293 | ||
294 | which more-or-less shadow %s's corresponding tables." | |
295 | parent map abbrev syntax parent)))) | |
296 | ||
297 | (unless (string-match (regexp-quote (symbol-name hook)) docstring) | |
298 | ;; Make sure the docstring mentions the mode's hook. | |
299 | (setq docstring | |
300 | (concat docstring | |
301 | (if (null parent) | |
302 | "\n\nThis mode " | |
303 | (concat | |
304 | "\n\nIn addition to any hooks its parent mode " | |
305 | (if (string-match (regexp-quote (format "`%s'" parent)) | |
306 | docstring) nil | |
307 | (format "`%s' " parent)) | |
308 | "might have run,\nthis mode ")) | |
309 | (format "runs the hook `%s'" hook) | |
310 | ", as the final step\nduring initialization."))) | |
311 | ||
312 | (unless (string-match "\\\\[{[]" docstring) | |
313 | ;; And don't forget to put the mode's keymap. | |
314 | (setq docstring (concat docstring "\n\n\\{" (symbol-name map) "}"))) | |
315 | ||
316 | docstring)) | |
317 | ||
318 | \f | |
319 | ;;; OBSOLETE | |
320 | ;; The functions below are only provided for backward compatibility with | |
321 | ;; code byte-compiled with versions of derived.el prior to Emacs-21. | |
322 | ||
323 | (defsubst derived-mode-setup-function-name (mode) | |
324 | "Construct a setup-function name based on a MODE name." | |
325 | (intern (concat (symbol-name mode) "-setup"))) | |
326 | ||
327 | \f | |
328 | ;; Utility functions for defining a derived mode. | |
329 | ||
330 | ;;;###autoload | |
331 | (defun derived-mode-init-mode-variables (mode) | |
a9873dbb | 332 | "Initialize variables for a new MODE. |
5e046f6d JB |
333 | Right now, if they don't already exist, set up a blank keymap, an |
334 | empty syntax table, and an empty abbrev table -- these will be merged | |
335 | the first time the mode is used." | |
336 | ||
337 | (if (boundp (derived-mode-map-name mode)) | |
338 | t | |
339 | (eval `(defvar ,(derived-mode-map-name mode) | |
340 | (make-sparse-keymap) | |
341 | ,(format "Keymap for %s." mode))) | |
342 | (put (derived-mode-map-name mode) 'derived-mode-unmerged t)) | |
343 | ||
344 | (if (boundp (derived-mode-syntax-table-name mode)) | |
345 | t | |
346 | (eval `(defvar ,(derived-mode-syntax-table-name mode) | |
347 | ;; Make a syntax table which doesn't specify anything | |
348 | ;; for any char. Valid data will be merged in by | |
349 | ;; derived-mode-merge-syntax-tables. | |
350 | (make-char-table 'syntax-table nil) | |
351 | ,(format "Syntax table for %s." mode))) | |
352 | (put (derived-mode-syntax-table-name mode) 'derived-mode-unmerged t)) | |
353 | ||
354 | (if (boundp (derived-mode-abbrev-table-name mode)) | |
355 | t | |
356 | (eval `(defvar ,(derived-mode-abbrev-table-name mode) | |
357 | (progn | |
358 | (define-abbrev-table (derived-mode-abbrev-table-name mode) nil) | |
359 | (make-abbrev-table)) | |
360 | ,(format "Abbrev table for %s." mode))))) | |
361 | \f | |
362 | ;; Utility functions for running a derived mode. | |
363 | ||
364 | (defun derived-mode-set-keymap (mode) | |
365 | "Set the keymap of the new MODE, maybe merging with the parent." | |
366 | (let* ((map-name (derived-mode-map-name mode)) | |
367 | (new-map (eval map-name)) | |
368 | (old-map (current-local-map))) | |
369 | (and old-map | |
370 | (get map-name 'derived-mode-unmerged) | |
371 | (derived-mode-merge-keymaps old-map new-map)) | |
372 | (put map-name 'derived-mode-unmerged nil) | |
373 | (use-local-map new-map))) | |
374 | ||
375 | (defun derived-mode-set-syntax-table (mode) | |
376 | "Set the syntax table of the new MODE, maybe merging with the parent." | |
377 | (let* ((table-name (derived-mode-syntax-table-name mode)) | |
378 | (old-table (syntax-table)) | |
379 | (new-table (eval table-name))) | |
380 | (if (get table-name 'derived-mode-unmerged) | |
381 | (derived-mode-merge-syntax-tables old-table new-table)) | |
382 | (put table-name 'derived-mode-unmerged nil) | |
383 | (set-syntax-table new-table))) | |
384 | ||
385 | (defun derived-mode-set-abbrev-table (mode) | |
386 | "Set the abbrev table for MODE if it exists. | |
387 | Always merge its parent into it, since the merge is non-destructive." | |
388 | (let* ((table-name (derived-mode-abbrev-table-name mode)) | |
389 | (old-table local-abbrev-table) | |
390 | (new-table (eval table-name))) | |
391 | (derived-mode-merge-abbrev-tables old-table new-table) | |
392 | (setq local-abbrev-table new-table))) | |
393 | ||
3c8dd9b9 JB |
394 | (defun derived-mode-run-hooks (mode) |
395 | "Run the mode hook for MODE." | |
396 | (let ((hooks-name (derived-mode-hook-name mode))) | |
397 | (if (boundp hooks-name) | |
398 | (run-hooks hooks-name)))) | |
399 | ||
5e046f6d JB |
400 | ;; Functions to merge maps and tables. |
401 | ||
402 | (defun derived-mode-merge-keymaps (old new) | |
403 | "Merge an OLD keymap into a NEW one. | |
404 | The old keymap is set to be the last cdr of the new one, so that there will | |
405 | be automatic inheritance." | |
406 | ;; ?? Can this just use `set-keymap-parent'? | |
407 | (let ((tail new)) | |
408 | ;; Scan the NEW map for prefix keys. | |
409 | (while (consp tail) | |
410 | (and (consp (car tail)) | |
411 | (let* ((key (vector (car (car tail)))) | |
412 | (subnew (lookup-key new key)) | |
413 | (subold (lookup-key old key))) | |
414 | ;; If KEY is a prefix key in both OLD and NEW, merge them. | |
415 | (and (keymapp subnew) (keymapp subold) | |
416 | (derived-mode-merge-keymaps subold subnew)))) | |
417 | (and (vectorp (car tail)) | |
418 | ;; Search a vector of ASCII char bindings for prefix keys. | |
419 | (let ((i (1- (length (car tail))))) | |
420 | (while (>= i 0) | |
421 | (let* ((key (vector i)) | |
422 | (subnew (lookup-key new key)) | |
423 | (subold (lookup-key old key))) | |
424 | ;; If KEY is a prefix key in both OLD and NEW, merge them. | |
425 | (and (keymapp subnew) (keymapp subold) | |
426 | (derived-mode-merge-keymaps subold subnew))) | |
427 | (setq i (1- i))))) | |
428 | (setq tail (cdr tail)))) | |
429 | (setcdr (nthcdr (1- (length new)) new) old)) | |
430 | ||
431 | (defun derived-mode-merge-syntax-tables (old new) | |
432 | "Merge an OLD syntax table into a NEW one. | |
433 | Where the new table already has an entry, nothing is copied from the old one." | |
434 | (set-char-table-parent new old)) | |
435 | ||
436 | ;; Merge an old abbrev table into a new one. | |
437 | ;; This function requires internal knowledge of how abbrev tables work, | |
438 | ;; presuming that they are obarrays with the abbrev as the symbol, the expansion | |
439 | ;; as the value of the symbol, and the hook as the function definition. | |
440 | (defun derived-mode-merge-abbrev-tables (old new) | |
441 | (if old | |
442 | (mapatoms | |
443 | (lambda (symbol) | |
444 | (or (intern-soft (symbol-name symbol) new) | |
445 | (define-abbrev new (symbol-name symbol) | |
446 | (symbol-value symbol) (symbol-function symbol)))) | |
447 | old))) | |
448 | ||
449 | (provide 'derived) | |
450 | ||
84ae4908 | 451 | ;; arch-tag: 630be248-47d1-4f02-afa0-8207de0ebea0 |
5e046f6d | 452 | ;;; derived.el ends here |