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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 |
931d0724 | 8 | ;; Keywords: obsolete |
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 | ||
c7ea3acc SM |
29 | ;; Obsolete. |
30 | ;; Use the `derived-major-mode' provided by easy-mmode.el instead. | |
8ccce2b0 SM |
31 | ;; It is only kept for backward compatibility with Emacs-20 byte-compiled |
32 | ;; files that refer to `derived-mode-init-mode-variables' and other functions. | |
c7ea3acc SM |
33 | |
34 | ||
35 | ||
76078cf0 RS |
36 | ;; GNU Emacs is already, in a sense, object oriented -- each object |
37 | ;; (buffer) belongs to a class (major mode), and that class defines | |
38 | ;; the relationship between messages (input events) and methods | |
39 | ;; (commands) by means of a keymap. | |
40 | ;; | |
41 | ;; The only thing missing is a good scheme of inheritance. It is | |
42 | ;; possible to simulate a single level of inheritance with generous | |
43 | ;; use of hooks and a bit of work -- sgml-mode, for example, also runs | |
44 | ;; the hooks for text-mode, and keymaps can inherit from other keymaps | |
45 | ;; -- but generally, each major mode ends up reinventing the wheel. | |
46 | ;; Ideally, someone should redesign all of Emacs's major modes to | |
47 | ;; follow a more conventional object-oriented system: when defining a | |
48 | ;; new major mode, the user should need only to name the existing mode | |
49 | ;; it is most similar to, then list the (few) differences. | |
50 | ;; | |
51 | ;; In the mean time, this package offers most of the advantages of | |
b72226e3 | 52 | ;; full inheritance with the existing major modes. The macro |
06d35594 | 53 | ;; `define-derived-mode' allows the user to make a variant of an existing |
76078cf0 RS |
54 | ;; major mode, with its own keymap. The new mode will inherit the key |
55 | ;; bindings of its parent, and will, in fact, run its parent first | |
56 | ;; every time it is called. For example, the commands | |
57 | ;; | |
06d35594 | 58 | ;; (define-derived-mode hypertext-mode text-mode "Hypertext" |
76078cf0 RS |
59 | ;; "Major mode for hypertext.\n\n\\{hypertext-mode-map}" |
60 | ;; (setq case-fold-search nil)) | |
61 | ;; | |
62 | ;; (define-key hypertext-mode-map [down-mouse-3] 'do-hyper-link) | |
63 | ;; | |
64 | ;; will create a function `hypertext-mode' with its own (sparse) | |
65 | ;; keymap `hypertext-mode-map.' The command M-x hypertext-mode will | |
66 | ;; perform the following actions: | |
67 | ;; | |
68 | ;; - run the command (text-mode) to get its default setup | |
69 | ;; - replace the current keymap with 'hypertext-mode-map,' which will | |
70 | ;; inherit from 'text-mode-map'. | |
71 | ;; - replace the current syntax table with | |
72 | ;; 'hypertext-mode-syntax-table', which will borrow its defaults | |
73 | ;; from the current text-mode-syntax-table. | |
26757b4b RS |
74 | ;; - replace the current abbrev table with |
75 | ;; 'hypertext-mode-abbrev-table', which will borrow its defaults | |
76 | ;; from the current text-mode-abbrev table | |
76078cf0 RS |
77 | ;; - change the mode line to read "Hypertext" |
78 | ;; - assign the value 'hypertext-mode' to the 'major-mode' variable | |
79 | ;; - run the body of commands provided in the macro -- in this case, | |
80 | ;; set the local variable `case-fold-search' to nil. | |
76078cf0 RS |
81 | ;; |
82 | ;; The advantages of this system are threefold. First, text mode is | |
83 | ;; untouched -- if you had added the new keystroke to `text-mode-map,' | |
84 | ;; possibly using hooks, you would have added it to all text buffers | |
85 | ;; -- here, it appears only in hypertext buffers, where it makes | |
06d35594 RS |
86 | ;; sense. Second, it is possible to build even further, and make |
87 | ;; a derived mode from a derived mode. The commands | |
76078cf0 | 88 | ;; |
06d35594 | 89 | ;; (define-derived-mode html-mode hypertext-mode "HTML") |
76078cf0 RS |
90 | ;; [various key definitions] |
91 | ;; | |
92 | ;; will add a new major mode for HTML with very little fuss. | |
93 | ;; | |
06d35594 RS |
94 | ;; Note also the function `derived-mode-class,' which returns the non-derived |
95 | ;; major mode which a derived mode is based on (ie. NOT necessarily the | |
76078cf0 RS |
96 | ;; immediate parent). |
97 | ;; | |
06d35594 RS |
98 | ;; (derived-mode-class 'text-mode) ==> text-mode |
99 | ;; (derived-mode-class 'hypertext-mode) ==> text-mode | |
100 | ;; (derived-mode-class 'html-mode) ==> text-mode | |
76078cf0 RS |
101 | \f |
102 | ;;; Code: | |
103 | ||
104 | ;; PUBLIC: define a new major mode which inherits from an existing one. | |
105 | ||
c7ea3acc | 106 | ;; ;;;###autoload |
8ccce2b0 SM |
107 | ;; Don't override the definition provided by easy-mmode.el |
108 | (unless (fboundp 'define-derived-mode) | |
06d35594 RS |
109 | (defmacro define-derived-mode (child parent name &optional docstring &rest body) |
110 | "Create a new mode as a variant of an existing mode. | |
76078cf0 RS |
111 | |
112 | The arguments to this command are as follow: | |
113 | ||
06d35594 | 114 | CHILD: the name of the command for the derived mode. |
04c817d4 DL |
115 | PARENT: the name of the command for the parent mode (e.g. `text-mode'). |
116 | NAME: a string which will appear in the status line (e.g. \"Hypertext\") | |
b72226e3 RS |
117 | DOCSTRING: an optional documentation string--if you do not supply one, |
118 | the function will attempt to invent something useful. | |
119 | BODY: forms to execute just before running the | |
76078cf0 RS |
120 | hooks for the new mode. |
121 | ||
06d35594 | 122 | Here is how you could define LaTeX-Thesis mode as a variant of LaTeX mode: |
76078cf0 | 123 | |
06d35594 | 124 | (define-derived-mode LaTeX-thesis-mode LaTeX-mode \"LaTeX-Thesis\") |
76078cf0 | 125 | |
b72226e3 RS |
126 | You could then make new key bindings for `LaTeX-thesis-mode-map' |
127 | without changing regular LaTeX mode. In this example, BODY is empty, | |
128 | and DOCSTRING is generated by default. | |
76078cf0 | 129 | |
04c817d4 | 130 | On a more complicated level, the following command uses `sgml-mode' as |
06d35594 | 131 | the parent, and then sets the variable `case-fold-search' to nil: |
76078cf0 | 132 | |
06d35594 | 133 | (define-derived-mode article-mode sgml-mode \"Article\" |
76078cf0 RS |
134 | \"Major mode for editing technical articles.\" |
135 | (setq case-fold-search nil)) | |
136 | ||
137 | Note that if the documentation string had been left out, it would have | |
138 | been generated automatically, with a reference to the keymap." | |
139 | ||
140 | ; Some trickiness, since what | |
141 | ; appears to be the docstring | |
142 | ; may really be the first | |
143 | ; element of the body. | |
144 | (if (and docstring (not (stringp docstring))) | |
145 | (progn (setq body (cons docstring body)) | |
146 | (setq docstring nil))) | |
06d35594 | 147 | (setq docstring (or docstring (derived-mode-make-docstring parent child))) |
76078cf0 | 148 | |
04c817d4 DL |
149 | `(progn |
150 | (derived-mode-init-mode-variables (quote ,child)) | |
151 | (defun ,child () | |
152 | ,docstring | |
153 | (interactive) | |
76078cf0 | 154 | ; Run the parent. |
04c817d4 | 155 | (,parent) |
76078cf0 | 156 | ; Identify special modes. |
04c817d4 DL |
157 | (if (get (quote ,parent) 'special) |
158 | (put (quote ,child) 'special t)) | |
76078cf0 | 159 | ; Identify the child mode. |
04c817d4 DL |
160 | (setq major-mode (quote ,child)) |
161 | (setq mode-name ,name) | |
76078cf0 | 162 | ; Set up maps and tables. |
04c817d4 DL |
163 | (derived-mode-set-keymap (quote ,child)) |
164 | (derived-mode-set-syntax-table (quote ,child)) | |
165 | (derived-mode-set-abbrev-table (quote ,child)) | |
76078cf0 | 166 | ; Splice in the body (if any). |
04c817d4 | 167 | ,@body |
b72226e3 RS |
168 | ;;; ; Run the setup function, if |
169 | ;;; ; any -- this will soon be | |
170 | ;;; ; obsolete. | |
04c817d4 DL |
171 | ;;; (derived-mode-run-setup-function (quote ,child)) |
172 | ; Run the hooks, if any. | |
8ccce2b0 | 173 | (derived-mode-run-hooks (quote ,child)))))) |
76078cf0 RS |
174 | |
175 | ||
06d35594 | 176 | ;; PUBLIC: find the ultimate class of a derived mode. |
76078cf0 | 177 | |
06d35594 | 178 | (defun derived-mode-class (mode) |
04c817d4 | 179 | "Find the class of a major MODE. |
06d35594 RS |
180 | A mode's class is the first ancestor which is NOT a derived mode. |
181 | Use the `derived-mode-parent' property of the symbol to trace backwards." | |
182 | (while (get mode 'derived-mode-parent) | |
183 | (setq mode (get mode 'derived-mode-parent))) | |
76078cf0 RS |
184 | mode) |
185 | ||
186 | \f | |
187 | ;; Inline functions to construct various names from a mode name. | |
188 | ||
06d35594 | 189 | (defsubst derived-mode-setup-function-name (mode) |
04c817d4 | 190 | "Construct a setup-function name based on a MODE name." |
76078cf0 RS |
191 | (intern (concat (symbol-name mode) "-setup"))) |
192 | ||
e2154af9 RS |
193 | (defsubst derived-mode-hook-name (mode) |
194 | "Construct the mode hook name based on mode name MODE." | |
195 | (intern (concat (symbol-name mode) "-hook"))) | |
76078cf0 | 196 | |
06d35594 | 197 | (defsubst derived-mode-map-name (mode) |
04c817d4 | 198 | "Construct a map name based on a MODE name." |
76078cf0 RS |
199 | (intern (concat (symbol-name mode) "-map"))) |
200 | ||
06d35594 | 201 | (defsubst derived-mode-syntax-table-name (mode) |
04c817d4 | 202 | "Construct a syntax-table name based on a MODE name." |
76078cf0 RS |
203 | (intern (concat (symbol-name mode) "-syntax-table"))) |
204 | ||
06d35594 | 205 | (defsubst derived-mode-abbrev-table-name (mode) |
04c817d4 | 206 | "Construct an abbrev-table name based on a MODE name." |
76078cf0 RS |
207 | (intern (concat (symbol-name mode) "-abbrev-table"))) |
208 | ||
209 | \f | |
06d35594 | 210 | ;; Utility functions for defining a derived mode. |
76078cf0 | 211 | |
ec830850 | 212 | ;;;###autoload |
06d35594 | 213 | (defun derived-mode-init-mode-variables (mode) |
04c817d4 | 214 | "Initialise variables for a new MODE. |
26757b4b RS |
215 | Right now, if they don't already exist, set up a blank keymap, an |
216 | empty syntax table, and an empty abbrev table -- these will be merged | |
217 | the first time the mode is used." | |
218 | ||
06d35594 | 219 | (if (boundp (derived-mode-map-name mode)) |
26757b4b | 220 | t |
04c817d4 | 221 | (eval `(defvar ,(derived-mode-map-name mode) |
26757b4b | 222 | (make-sparse-keymap) |
04c817d4 | 223 | ,(format "Keymap for %s." mode))) |
06d35594 | 224 | (put (derived-mode-map-name mode) 'derived-mode-unmerged t)) |
26757b4b | 225 | |
06d35594 | 226 | (if (boundp (derived-mode-syntax-table-name mode)) |
26757b4b | 227 | t |
04c817d4 DL |
228 | (eval `(defvar ,(derived-mode-syntax-table-name mode) |
229 | ;; Make a syntax table which doesn't specify anything | |
230 | ;; for any char. Valid data will be merged in by | |
231 | ;; derived-mode-merge-syntax-tables. | |
232 | (make-char-table 'syntax-table nil) | |
233 | ,(format "Syntax table for %s." mode))) | |
06d35594 | 234 | (put (derived-mode-syntax-table-name mode) 'derived-mode-unmerged t)) |
26757b4b | 235 | |
06d35594 | 236 | (if (boundp (derived-mode-abbrev-table-name mode)) |
26757b4b | 237 | t |
04c817d4 DL |
238 | (eval `(defvar ,(derived-mode-abbrev-table-name mode) |
239 | (progn | |
240 | (define-abbrev-table (derived-mode-abbrev-table-name mode) nil) | |
241 | (make-abbrev-table)) | |
242 | ,(format "Abbrev table for %s." mode))))) | |
76078cf0 | 243 | |
06d35594 | 244 | (defun derived-mode-make-docstring (parent child) |
76078cf0 RS |
245 | "Construct a docstring for a new mode if none is provided." |
246 | ||
06d35594 | 247 | (format "This major mode is a variant of `%s', created by `define-derived-mode'. |
b72226e3 RS |
248 | It inherits all of the parent's attributes, but has its own keymap, |
249 | abbrev table and syntax table: | |
76078cf0 | 250 | |
b72226e3 | 251 | `%s-map' and `%s-syntax-table' |
76078cf0 RS |
252 | |
253 | which more-or-less shadow | |
254 | ||
b72226e3 | 255 | `%s-map' and `%s-syntax-table' |
76078cf0 RS |
256 | |
257 | \\{%s-map}" parent child child parent parent child)) | |
258 | ||
259 | \f | |
06d35594 | 260 | ;; Utility functions for running a derived mode. |
76078cf0 | 261 | |
06d35594 | 262 | (defun derived-mode-set-keymap (mode) |
04c817d4 | 263 | "Set the keymap of the new MODE, maybe merging with the parent." |
06d35594 | 264 | (let* ((map-name (derived-mode-map-name mode)) |
76078cf0 RS |
265 | (new-map (eval map-name)) |
266 | (old-map (current-local-map))) | |
f34e6918 RS |
267 | (and old-map |
268 | (get map-name 'derived-mode-unmerged) | |
269 | (derived-mode-merge-keymaps old-map new-map)) | |
06d35594 | 270 | (put map-name 'derived-mode-unmerged nil) |
26757b4b | 271 | (use-local-map new-map))) |
76078cf0 | 272 | |
04c817d4 DL |
273 | (defun derived-mode-set-syntax-table (mode) |
274 | "Set the syntax table of the new MODE, maybe merging with the parent." | |
06d35594 | 275 | (let* ((table-name (derived-mode-syntax-table-name mode)) |
76078cf0 RS |
276 | (old-table (syntax-table)) |
277 | (new-table (eval table-name))) | |
06d35594 RS |
278 | (if (get table-name 'derived-mode-unmerged) |
279 | (derived-mode-merge-syntax-tables old-table new-table)) | |
280 | (put table-name 'derived-mode-unmerged nil) | |
26757b4b | 281 | (set-syntax-table new-table))) |
76078cf0 | 282 | |
06d35594 | 283 | (defun derived-mode-set-abbrev-table (mode) |
04c817d4 | 284 | "Set the abbrev table for MODE if it exists. |
26757b4b | 285 | Always merge its parent into it, since the merge is non-destructive." |
06d35594 | 286 | (let* ((table-name (derived-mode-abbrev-table-name mode)) |
26757b4b RS |
287 | (old-table local-abbrev-table) |
288 | (new-table (eval table-name))) | |
06d35594 | 289 | (derived-mode-merge-abbrev-tables old-table new-table) |
26757b4b | 290 | (setq local-abbrev-table new-table))) |
76078cf0 | 291 | |
06d35594 | 292 | ;;;(defun derived-mode-run-setup-function (mode) |
b72226e3 | 293 | ;;; "Run the setup function if it exists." |
76078cf0 | 294 | |
06d35594 | 295 | ;;; (let ((fname (derived-mode-setup-function-name mode))) |
b72226e3 RS |
296 | ;;; (if (fboundp fname) |
297 | ;;; (funcall fname)))) | |
76078cf0 | 298 | |
06d35594 | 299 | (defun derived-mode-run-hooks (mode) |
e2154af9 | 300 | "Run the mode hook for MODE." |
76078cf0 | 301 | |
e2154af9 | 302 | (let ((hooks-name (derived-mode-hook-name mode))) |
76078cf0 RS |
303 | (if (boundp hooks-name) |
304 | (run-hooks hooks-name)))) | |
305 | ||
306 | ;; Functions to merge maps and tables. | |
307 | ||
06d35594 | 308 | (defun derived-mode-merge-keymaps (old new) |
04c817d4 | 309 | "Merge an OLD keymap into a NEW one. |
37a4f4b6 | 310 | The old keymap is set to be the last cdr of the new one, so that there will |
76078cf0 | 311 | be automatic inheritance." |
04c817d4 | 312 | ;; ?? Can this just use `set-keymap-parent'? |
37a4f4b6 RS |
313 | (let ((tail new)) |
314 | ;; Scan the NEW map for prefix keys. | |
315 | (while (consp tail) | |
316 | (and (consp (car tail)) | |
317 | (let* ((key (vector (car (car tail)))) | |
318 | (subnew (lookup-key new key)) | |
319 | (subold (lookup-key old key))) | |
320 | ;; If KEY is a prefix key in both OLD and NEW, merge them. | |
321 | (and (keymapp subnew) (keymapp subold) | |
322 | (derived-mode-merge-keymaps subold subnew)))) | |
323 | (and (vectorp (car tail)) | |
324 | ;; Search a vector of ASCII char bindings for prefix keys. | |
325 | (let ((i (1- (length (car tail))))) | |
326 | (while (>= i 0) | |
327 | (let* ((key (vector i)) | |
328 | (subnew (lookup-key new key)) | |
329 | (subold (lookup-key old key))) | |
330 | ;; If KEY is a prefix key in both OLD and NEW, merge them. | |
331 | (and (keymapp subnew) (keymapp subold) | |
332 | (derived-mode-merge-keymaps subold subnew))) | |
333 | (setq i (1- i))))) | |
334 | (setq tail (cdr tail)))) | |
26757b4b | 335 | (setcdr (nthcdr (1- (length new)) new) old)) |
76078cf0 | 336 | |
06d35594 | 337 | (defun derived-mode-merge-syntax-tables (old new) |
04c817d4 | 338 | "Merge an OLD syntax table into a NEW one. |
76078cf0 | 339 | Where the new table already has an entry, nothing is copied from the old one." |
5dee7dae | 340 | (set-char-table-parent new old)) |
26757b4b | 341 | |
56152e17 RS |
342 | ;; Merge an old abbrev table into a new one. |
343 | ;; This function requires internal knowledge of how abbrev tables work, | |
344 | ;; presuming that they are obarrays with the abbrev as the symbol, the expansion | |
345 | ;; as the value of the symbol, and the hook as the function definition. | |
06d35594 | 346 | (defun derived-mode-merge-abbrev-tables (old new) |
56152e17 | 347 | (if old |
04c817d4 DL |
348 | (mapatoms |
349 | (lambda (symbol) | |
350 | (or (intern-soft (symbol-name symbol) new) | |
351 | (define-abbrev new (symbol-name symbol) | |
352 | (symbol-value symbol) (symbol-function symbol)))) | |
56152e17 | 353 | old))) |
76078cf0 | 354 | |
06d35594 | 355 | (provide 'derived) |
26757b4b | 356 | |
06d35594 | 357 | ;;; derived.el ends here |