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1 | ;;; derived.el --- allow inheritance of major modes |
2 | ;;; (formerly mode-clone.el) | |
3 | ||
4 | ;; Copyright (C) 1993, 1994, 1999, 2003 Free Software Foundation, Inc. | |
5 | ||
6 | ;; Author: David Megginson (dmeggins@aix1.uottawa.ca) | |
7 | ;; Maintainer: FSF | |
8 | ;; Keywords: extensions | |
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 | |
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. | |
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 | |
45 | ;; full inheritance with the existing major modes. The macro | |
46 | ;; `define-derived-mode' allows the user to make a variant of an existing | |
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 | ;; | |
51 | ;; (define-derived-mode hypertext-mode text-mode "Hypertext" | |
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. | |
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 | |
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. | |
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 | |
79 | ;; sense. Second, it is possible to build even further, and make | |
80 | ;; a derived mode from a derived mode. The commands | |
81 | ;; | |
82 | ;; (define-derived-mode html-mode hypertext-mode "HTML") | |
83 | ;; [various key definitions] | |
84 | ;; | |
85 | ;; will add a new major mode for HTML with very little fuss. | |
86 | ;; | |
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). | |
91 | \f | |
92 | ;;; Code: | |
93 | ||
94 | (eval-when-compile (require 'cl)) | |
95 | ||
96 | ;;; PRIVATE: defsubst must be defined before they are first used | |
97 | ||
98 | (defsubst derived-mode-hook-name (mode) | |
99 | "Construct the mode hook name based on mode name MODE." | |
100 | (intern (concat (symbol-name mode) "-hook"))) | |
101 | ||
102 | (defsubst derived-mode-map-name (mode) | |
103 | "Construct a map name based on a MODE name." | |
104 | (intern (concat (symbol-name mode) "-map"))) | |
105 | ||
106 | (defsubst derived-mode-syntax-table-name (mode) | |
107 | "Construct a syntax-table name based on a MODE name." | |
108 | (intern (concat (symbol-name mode) "-syntax-table"))) | |
109 | ||
110 | (defsubst derived-mode-abbrev-table-name (mode) | |
111 | "Construct an abbrev-table name based on a MODE name." | |
112 | (intern (concat (symbol-name mode) "-abbrev-table"))) | |
113 | ||
114 | ;; PUBLIC: define a new major mode which inherits from an existing one. | |
115 | ||
116 | ;;;###autoload | |
117 | (defmacro define-derived-mode (child parent name &optional docstring &rest body) | |
118 | "Create a new mode as a variant of an existing mode. | |
119 | ||
120 | The arguments to this command are as follow: | |
121 | ||
122 | CHILD: the name of the command for the derived mode. | |
123 | PARENT: the name of the command for the parent mode (e.g. `text-mode') | |
124 | or nil if there is no parent. | |
125 | NAME: a string which will appear in the status line (e.g. \"Hypertext\") | |
126 | DOCSTRING: an optional documentation string--if you do not supply one, | |
127 | the function will attempt to invent something useful. | |
128 | BODY: forms to execute just before running the | |
129 | hooks for the new mode. Do not use `interactive' here. | |
130 | ||
131 | BODY can start with a bunch of keyword arguments. The following keyword | |
132 | arguments are currently understood: | |
133 | :group GROUP | |
134 | Declare the customization group that corresponds to this mode. | |
135 | :syntax-table TABLE | |
136 | Use TABLE instead of the default. | |
137 | A nil value means to simply use the same syntax-table as the parent. | |
138 | :abbrev-table TABLE | |
139 | Use TABLE instead of the default. | |
140 | A nil value means to simply use the same abbrev-table as the parent. | |
141 | ||
142 | Here is how you could define LaTeX-Thesis mode as a variant of LaTeX mode: | |
143 | ||
144 | (define-derived-mode LaTeX-thesis-mode LaTeX-mode \"LaTeX-Thesis\") | |
145 | ||
146 | You could then make new key bindings for `LaTeX-thesis-mode-map' | |
147 | without changing regular LaTeX mode. In this example, BODY is empty, | |
148 | and DOCSTRING is generated by default. | |
149 | ||
150 | On a more complicated level, the following command uses `sgml-mode' as | |
151 | the parent, and then sets the variable `case-fold-search' to nil: | |
152 | ||
153 | (define-derived-mode article-mode sgml-mode \"Article\" | |
154 | \"Major mode for editing technical articles.\" | |
155 | (setq case-fold-search nil)) | |
156 | ||
157 | Note that if the documentation string had been left out, it would have | |
8d11b450 GM |
158 | been generated automatically, with a reference to the keymap. |
159 | ||
160 | The new mode runs the hook constructed by the function | |
161 | `derived-mode-hook-name'." | |
5e046f6d JB |
162 | (declare (debug (&define name symbolp sexp [&optional stringp] |
163 | [&rest keywordp sexp] def-body))) | |
164 | ||
165 | (when (and docstring (not (stringp docstring))) | |
166 | ;; Some trickiness, since what appears to be the docstring may really be | |
167 | ;; the first element of the body. | |
168 | (push docstring body) | |
169 | (setq docstring nil)) | |
170 | ||
171 | (when (eq parent 'fundamental-mode) (setq parent nil)) | |
172 | ||
173 | (let ((map (derived-mode-map-name child)) | |
174 | (syntax (derived-mode-syntax-table-name child)) | |
175 | (abbrev (derived-mode-abbrev-table-name child)) | |
176 | (declare-abbrev t) | |
177 | (declare-syntax t) | |
178 | (hook (derived-mode-hook-name child)) | |
179 | (group nil)) | |
180 | ||
181 | ;; Process the keyword args. | |
182 | (while (keywordp (car body)) | |
183 | (case (pop body) | |
184 | (:group (setq group (pop body))) | |
185 | (:abbrev-table (setq abbrev (pop body)) (setq declare-abbrev nil)) | |
186 | (:syntax-table (setq syntax (pop body)) (setq declare-syntax nil)) | |
187 | (t (pop body)))) | |
188 | ||
189 | (setq docstring (derived-mode-make-docstring | |
190 | parent child docstring syntax abbrev)) | |
191 | ||
192 | `(progn | |
8d11b450 | 193 | (defvar ,hook nil ,(format "Hook run when entering %s mode." name)) |
5e046f6d JB |
194 | (defvar ,map (make-sparse-keymap)) |
195 | ,(if declare-syntax | |
196 | `(defvar ,syntax (make-syntax-table))) | |
197 | ,(if declare-abbrev | |
198 | `(defvar ,abbrev | |
199 | (progn (define-abbrev-table ',abbrev nil) ,abbrev))) | |
200 | (put ',child 'derived-mode-parent ',parent) | |
201 | ,(if group `(put ',child 'custom-mode-group ,group)) | |
202 | ||
203 | (defun ,child () | |
204 | ,docstring | |
205 | (interactive) | |
206 | ; Run the parent. | |
207 | (delay-mode-hooks | |
208 | ||
209 | (,(or parent 'kill-all-local-variables)) | |
210 | ; Identify the child mode. | |
211 | (setq major-mode (quote ,child)) | |
212 | (setq mode-name ,name) | |
213 | ; Identify special modes. | |
214 | ,(when parent | |
215 | `(progn | |
216 | (if (get (quote ,parent) 'mode-class) | |
217 | (put (quote ,child) 'mode-class | |
218 | (get (quote ,parent) 'mode-class))) | |
219 | ; Set up maps and tables. | |
220 | (unless (keymap-parent ,map) | |
221 | (set-keymap-parent ,map (current-local-map))) | |
222 | ,(when declare-syntax | |
223 | `(let ((parent (char-table-parent ,syntax))) | |
224 | (unless (and parent | |
225 | (not (eq parent (standard-syntax-table)))) | |
226 | (set-char-table-parent ,syntax (syntax-table))))))) | |
227 | ||
228 | (use-local-map ,map) | |
229 | ,(when syntax `(set-syntax-table ,syntax)) | |
230 | ,(when abbrev `(setq local-abbrev-table ,abbrev)) | |
231 | ; Splice in the body (if any). | |
232 | ,@body | |
233 | ) | |
234 | ;; Run the hooks, if any. | |
235 | ;; Make the generated code work in older Emacs versions | |
236 | ;; that do not yet have run-mode-hooks. | |
237 | (if (fboundp 'run-mode-hooks) | |
238 | (run-mode-hooks ',hook) | |
239 | (run-hooks ',hook)))))) | |
240 | ||
241 | ;; PUBLIC: find the ultimate class of a derived mode. | |
242 | ||
243 | (defun derived-mode-class (mode) | |
244 | "Find the class of a major MODE. | |
245 | A mode's class is the first ancestor which is NOT a derived mode. | |
246 | Use the `derived-mode-parent' property of the symbol to trace backwards. | |
247 | Since major-modes might all derive from `fundamental-mode', this function | |
248 | is not very useful." | |
249 | (while (get mode 'derived-mode-parent) | |
250 | (setq mode (get mode 'derived-mode-parent))) | |
251 | mode) | |
252 | (make-obsolete 'derived-mode-class 'derived-mode-p "21.4") | |
253 | ||
254 | \f | |
255 | ;;; PRIVATE | |
256 | ||
257 | (defun derived-mode-make-docstring (parent child &optional | |
258 | docstring syntax abbrev) | |
259 | "Construct a docstring for a new mode if none is provided." | |
260 | ||
261 | (let ((map (derived-mode-map-name child)) | |
262 | (hook (derived-mode-hook-name child))) | |
263 | ||
264 | (unless (stringp docstring) | |
265 | ;; Use a default docstring. | |
266 | (setq docstring | |
267 | (if (null parent) | |
268 | (format "Major-mode. | |
269 | Uses keymap `%s', abbrev table `%s' and syntax-table `%s'." map abbrev syntax) | |
270 | (format "Major mode derived from `%s' by `define-derived-mode'. | |
271 | It inherits all of the parent's attributes, but has its own keymap, | |
272 | abbrev table and syntax table: | |
273 | ||
274 | `%s', `%s' and `%s' | |
275 | ||
276 | which more-or-less shadow %s's corresponding tables." | |
277 | parent map abbrev syntax parent)))) | |
278 | ||
279 | (unless (string-match (regexp-quote (symbol-name hook)) docstring) | |
280 | ;; Make sure the docstring mentions the mode's hook. | |
281 | (setq docstring | |
282 | (concat docstring | |
283 | (if (null parent) | |
284 | "\n\nThis mode " | |
285 | (concat | |
286 | "\n\nIn addition to any hooks its parent mode " | |
287 | (if (string-match (regexp-quote (format "`%s'" parent)) | |
288 | docstring) nil | |
289 | (format "`%s' " parent)) | |
290 | "might have run,\nthis mode ")) | |
291 | (format "runs the hook `%s'" hook) | |
292 | ", as the final step\nduring initialization."))) | |
293 | ||
294 | (unless (string-match "\\\\[{[]" docstring) | |
295 | ;; And don't forget to put the mode's keymap. | |
296 | (setq docstring (concat docstring "\n\n\\{" (symbol-name map) "}"))) | |
297 | ||
298 | docstring)) | |
299 | ||
300 | \f | |
301 | ;;; OBSOLETE | |
302 | ;; The functions below are only provided for backward compatibility with | |
303 | ;; code byte-compiled with versions of derived.el prior to Emacs-21. | |
304 | ||
305 | (defsubst derived-mode-setup-function-name (mode) | |
306 | "Construct a setup-function name based on a MODE name." | |
307 | (intern (concat (symbol-name mode) "-setup"))) | |
308 | ||
309 | \f | |
310 | ;; Utility functions for defining a derived mode. | |
311 | ||
312 | ;;;###autoload | |
313 | (defun derived-mode-init-mode-variables (mode) | |
314 | "Initialise variables for a new MODE. | |
315 | Right now, if they don't already exist, set up a blank keymap, an | |
316 | empty syntax table, and an empty abbrev table -- these will be merged | |
317 | the first time the mode is used." | |
318 | ||
319 | (if (boundp (derived-mode-map-name mode)) | |
320 | t | |
321 | (eval `(defvar ,(derived-mode-map-name mode) | |
322 | (make-sparse-keymap) | |
323 | ,(format "Keymap for %s." mode))) | |
324 | (put (derived-mode-map-name mode) 'derived-mode-unmerged t)) | |
325 | ||
326 | (if (boundp (derived-mode-syntax-table-name mode)) | |
327 | t | |
328 | (eval `(defvar ,(derived-mode-syntax-table-name mode) | |
329 | ;; Make a syntax table which doesn't specify anything | |
330 | ;; for any char. Valid data will be merged in by | |
331 | ;; derived-mode-merge-syntax-tables. | |
332 | (make-char-table 'syntax-table nil) | |
333 | ,(format "Syntax table for %s." mode))) | |
334 | (put (derived-mode-syntax-table-name mode) 'derived-mode-unmerged t)) | |
335 | ||
336 | (if (boundp (derived-mode-abbrev-table-name mode)) | |
337 | t | |
338 | (eval `(defvar ,(derived-mode-abbrev-table-name mode) | |
339 | (progn | |
340 | (define-abbrev-table (derived-mode-abbrev-table-name mode) nil) | |
341 | (make-abbrev-table)) | |
342 | ,(format "Abbrev table for %s." mode))))) | |
343 | \f | |
344 | ;; Utility functions for running a derived mode. | |
345 | ||
346 | (defun derived-mode-set-keymap (mode) | |
347 | "Set the keymap of the new MODE, maybe merging with the parent." | |
348 | (let* ((map-name (derived-mode-map-name mode)) | |
349 | (new-map (eval map-name)) | |
350 | (old-map (current-local-map))) | |
351 | (and old-map | |
352 | (get map-name 'derived-mode-unmerged) | |
353 | (derived-mode-merge-keymaps old-map new-map)) | |
354 | (put map-name 'derived-mode-unmerged nil) | |
355 | (use-local-map new-map))) | |
356 | ||
357 | (defun derived-mode-set-syntax-table (mode) | |
358 | "Set the syntax table of the new MODE, maybe merging with the parent." | |
359 | (let* ((table-name (derived-mode-syntax-table-name mode)) | |
360 | (old-table (syntax-table)) | |
361 | (new-table (eval table-name))) | |
362 | (if (get table-name 'derived-mode-unmerged) | |
363 | (derived-mode-merge-syntax-tables old-table new-table)) | |
364 | (put table-name 'derived-mode-unmerged nil) | |
365 | (set-syntax-table new-table))) | |
366 | ||
367 | (defun derived-mode-set-abbrev-table (mode) | |
368 | "Set the abbrev table for MODE if it exists. | |
369 | Always merge its parent into it, since the merge is non-destructive." | |
370 | (let* ((table-name (derived-mode-abbrev-table-name mode)) | |
371 | (old-table local-abbrev-table) | |
372 | (new-table (eval table-name))) | |
373 | (derived-mode-merge-abbrev-tables old-table new-table) | |
374 | (setq local-abbrev-table new-table))) | |
375 | ||
376 | ;;;(defun derived-mode-run-setup-function (mode) | |
377 | ;;; "Run the setup function if it exists." | |
378 | ||
379 | ;;; (let ((fname (derived-mode-setup-function-name mode))) | |
380 | ;;; (if (fboundp fname) | |
381 | ;;; (funcall fname)))) | |
382 | ||
383 | (defun derived-mode-run-hooks (mode) | |
384 | "Run the mode hook for MODE." | |
385 | (let ((hooks-name (derived-mode-hook-name mode))) | |
386 | (if (boundp hooks-name) | |
387 | (run-hooks hooks-name)))) | |
388 | ||
389 | ;; Functions to merge maps and tables. | |
390 | ||
391 | (defun derived-mode-merge-keymaps (old new) | |
392 | "Merge an OLD keymap into a NEW one. | |
393 | The old keymap is set to be the last cdr of the new one, so that there will | |
394 | be automatic inheritance." | |
395 | ;; ?? Can this just use `set-keymap-parent'? | |
396 | (let ((tail new)) | |
397 | ;; Scan the NEW map for prefix keys. | |
398 | (while (consp tail) | |
399 | (and (consp (car tail)) | |
400 | (let* ((key (vector (car (car tail)))) | |
401 | (subnew (lookup-key new key)) | |
402 | (subold (lookup-key old key))) | |
403 | ;; If KEY is a prefix key in both OLD and NEW, merge them. | |
404 | (and (keymapp subnew) (keymapp subold) | |
405 | (derived-mode-merge-keymaps subold subnew)))) | |
406 | (and (vectorp (car tail)) | |
407 | ;; Search a vector of ASCII char bindings for prefix keys. | |
408 | (let ((i (1- (length (car tail))))) | |
409 | (while (>= i 0) | |
410 | (let* ((key (vector i)) | |
411 | (subnew (lookup-key new key)) | |
412 | (subold (lookup-key old key))) | |
413 | ;; If KEY is a prefix key in both OLD and NEW, merge them. | |
414 | (and (keymapp subnew) (keymapp subold) | |
415 | (derived-mode-merge-keymaps subold subnew))) | |
416 | (setq i (1- i))))) | |
417 | (setq tail (cdr tail)))) | |
418 | (setcdr (nthcdr (1- (length new)) new) old)) | |
419 | ||
420 | (defun derived-mode-merge-syntax-tables (old new) | |
421 | "Merge an OLD syntax table into a NEW one. | |
422 | Where the new table already has an entry, nothing is copied from the old one." | |
423 | (set-char-table-parent new old)) | |
424 | ||
425 | ;; Merge an old abbrev table into a new one. | |
426 | ;; This function requires internal knowledge of how abbrev tables work, | |
427 | ;; presuming that they are obarrays with the abbrev as the symbol, the expansion | |
428 | ;; as the value of the symbol, and the hook as the function definition. | |
429 | (defun derived-mode-merge-abbrev-tables (old new) | |
430 | (if old | |
431 | (mapatoms | |
432 | (lambda (symbol) | |
433 | (or (intern-soft (symbol-name symbol) new) | |
434 | (define-abbrev new (symbol-name symbol) | |
435 | (symbol-value symbol) (symbol-function symbol)))) | |
436 | old))) | |
437 | ||
438 | (provide 'derived) | |
439 | ||
6b61353c | 440 | ;;; arch-tag: 630be248-47d1-4f02-afa0-8207de0ebea0 |
5e046f6d | 441 | ;;; derived.el ends here |