1 ;;; derived.el --- allow inheritance of major modes
2 ;;; (formerly mode-clone.el)
4 ;; Copyright (C) 1993, 1994, 1999, 2003 Free Software Foundation, Inc.
6 ;; Author: David Megginson (dmeggins@aix1.uottawa.ca)
7 ;; Maintainer: SXEmacs Development Team
8 ;; Keywords: extensions, dumped
10 ;; This file is part of SXEmacs.
12 ;; SXEmacs 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 3 of the License, or
15 ;; (at your option) any later version.
17 ;; SXEmacs 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.
22 ;; You should have received a copy of the GNU General Public License
23 ;; along with this program. If not, see <http://www.gnu.org/licenses/>.
25 ;;; Synched up with: FSF 21.3.
29 ;; This file is dumped with SXEmacs.
31 ;; XEmacs is already, in a sense, object oriented -- each object
32 ;; (buffer) belongs to a class (major mode), and that class defines
33 ;; the relationship between messages (input events) and methods
34 ;; (commands) by means of a keymap.
36 ;; The only thing missing is a good scheme of inheritance. It is
37 ;; possible to simulate a single level of inheritance with generous
38 ;; use of hooks and a bit of work -- sgml-mode, for example, also runs
39 ;; the hooks for text-mode, and keymaps can inherit from other keymaps
40 ;; -- but generally, each major mode ends up reinventing the wheel.
41 ;; Ideally, someone should redesign all of Emacs's major modes to
42 ;; follow a more conventional object-oriented system: when defining a
43 ;; new major mode, the user should need only to name the existing mode
44 ;; it is most similar to, then list the (few) differences.
46 ;; In the mean time, this package offers most of the advantages of
47 ;; full inheritance with the existing major modes. The macro
48 ;; `define-derived-mode' allows the user to make a variant of an existing
49 ;; major mode, with its own keymap. The new mode will inherit the key
50 ;; bindings of its parent, and will, in fact, run its parent first
51 ;; every time it is called. For example, the commands
53 ;; (define-derived-mode hypertext-mode text-mode "Hypertext"
54 ;; "Major mode for hypertext.\n\n\\{hypertext-mode-map}"
55 ;; (setq case-fold-search nil))
57 ;; (define-key hypertext-mode-map [down-mouse-3] 'do-hyper-link)
59 ;; will create a function `hypertext-mode' with its own (sparse)
60 ;; keymap `hypertext-mode-map.' The command M-x hypertext-mode will
61 ;; perform the following actions:
63 ;; - run the command (text-mode) to get its default setup
64 ;; - replace the current keymap with 'hypertext-mode-map,' which will
65 ;; inherit from 'text-mode-map'.
66 ;; - replace the current syntax table with
67 ;; 'hypertext-mode-syntax-table', which will borrow its defaults
68 ;; from the current text-mode-syntax-table.
69 ;; - replace the current abbrev table with
70 ;; 'hypertext-mode-abbrev-table', which will borrow its defaults
71 ;; from the current text-mode-abbrev table
72 ;; - change the mode line to read "Hypertext"
73 ;; - assign the value 'hypertext-mode' to the 'major-mode' variable
74 ;; - run the body of commands provided in the macro -- in this case,
75 ;; set the local variable `case-fold-search' to nil.
77 ;; The advantages of this system are threefold. First, text mode is
78 ;; untouched -- if you had added the new keystroke to `text-mode-map,'
79 ;; possibly using hooks, you would have added it to all text buffers
80 ;; -- here, it appears only in hypertext buffers, where it makes
81 ;; sense. Second, it is possible to build even further, and make
82 ;; a derived mode from a derived mode. The commands
84 ;; (define-derived-mode html-mode hypertext-mode "HTML")
85 ;; [various key definitions]
87 ;; will add a new major mode for HTML with very little fuss.
89 ;; Note also the function `derived-mode-p' which can tell if the current
90 ;; mode derives from another. In a hypertext-mode, buffer, for example,
91 ;; (derived-mode-p 'text-mode) would return non-nil. This should always
92 ;; be used in place of (eq major-mode 'text-mode).
96 ;;; PRIVATE: defsubst must be defined before they are first used
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")))
102 (defsubst derived-mode-map-name (mode)
103 "Construct a map name based on a MODE name."
104 (intern (concat (symbol-name mode) "-map")))
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")))
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")))
114 ;; PUBLIC: define a new major mode which inherits from an existing one.
116 ;; XEmacs -- no 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.
120 The arguments to this command are as follow:
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.
131 BODY can start with a bunch of keyword arguments. The following keyword
132 arguments are currently understood:
134 Declare the customization group that corresponds to this mode.
136 Use TABLE instead of the default.
137 A nil value means to simply use the same syntax-table as the parent.
139 Use TABLE instead of the default.
140 A nil value means to simply use the same abbrev-table as the parent.
142 Here is how you could define LaTeX-Thesis mode as a variant of LaTeX mode:
144 (define-derived-mode LaTeX-thesis-mode LaTeX-mode \"LaTeX-Thesis\")
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.
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:
153 (define-derived-mode article-mode sgml-mode \"Article\"
154 \"Major mode for editing technical articles.\"
155 (setq case-fold-search nil))
157 Note that if the documentation string had been left out, it would have
158 been generated automatically, with a reference to the keymap.
160 The new mode runs the hook constructed by the function
161 `derived-mode-hook-name'."
162 (declare (debug (&define name symbolp sexp [&optional stringp]
163 [&rest keywordp sexp] def-body)))
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))
171 (when (eq parent 'fundamental-mode) (setq parent nil))
173 (let ((map (derived-mode-map-name child))
174 (syntax (derived-mode-syntax-table-name child))
175 (abbrev (derived-mode-abbrev-table-name child))
178 (hook (derived-mode-hook-name child))
181 ;; Process the keyword args.
182 (while (keywordp (car 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))
189 (setq docstring (derived-mode-make-docstring
190 parent child docstring syntax abbrev))
193 (defvar ,hook nil ,(format "Hook run when entering %s mode." name))
194 (defvar ,map (make-sparse-keymap))
196 `(defvar ,syntax (make-syntax-table)))
199 (progn (define-abbrev-table ',abbrev nil) ,abbrev)))
200 (put ',child 'derived-mode-parent ',parent)
201 ,(if group `(put ',child 'custom-mode-group ,group))
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.
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-parents ,map (list (current-local-map))))
222 ,(when declare-syntax
223 ;; XEmacs change: we do not have char-table-parent
224 `(derived-mode-merge-syntax-tables
225 (syntax-table) ,syntax))))
228 ,(when syntax `(set-syntax-table ,syntax))
229 ,(when abbrev `(setq local-abbrev-table ,abbrev))
230 ; Splice in the body (if any).
233 ;; Run the hooks, if any.
234 ;; Make the generated code work in older Emacs versions
235 ;; that do not yet have run-mode-hooks.
236 (if (fboundp 'run-mode-hooks)
237 (run-mode-hooks ',hook)
238 (run-hooks ',hook))))))
240 ;; PUBLIC: find the ultimate class of a derived mode.
242 (defun derived-mode-class (mode)
243 "Find the class of a major MODE.
244 A mode's class is the first ancestor which is NOT a derived mode.
245 Use the `derived-mode-parent' property of the symbol to trace backwards.
246 Since major-modes might all derive from `fundamental-mode', this function
248 (while (get mode 'derived-mode-parent)
249 (setq mode (get mode 'derived-mode-parent)))
251 (make-obsolete 'derived-mode-class 'derived-mode-p)
253 ;; PUBLIC: find if the current mode derives from another.
254 ;; from GNU Emacs 21 subr.el
256 (defun derived-mode-p (&rest modes)
257 "Non-nil if the current major mode is derived from one of MODES.
258 Uses the `derived-mode-parent' property of the symbol to trace backwards."
259 (let ((parent major-mode))
260 (while (and (not (memq parent modes))
261 (setq parent (get parent 'derived-mode-parent))))
267 (defun derived-mode-make-docstring (parent child &optional
268 docstring syntax abbrev)
269 "Construct a docstring for a new mode if none is provided."
271 (let ((map (derived-mode-map-name child))
272 (hook (derived-mode-hook-name child)))
274 (unless (stringp docstring)
275 ;; Use a default docstring.
279 Uses keymap `%s', abbrev table `%s' and syntax-table `%s'." map abbrev syntax)
280 (format "Major mode derived from `%s' by `define-derived-mode'.
281 It inherits all of the parent's attributes, but has its own keymap,
282 abbrev table and syntax table:
286 which more-or-less shadow %s's corresponding tables."
287 parent map abbrev syntax parent))))
289 (unless (string-match (regexp-quote (symbol-name hook)) docstring)
290 ;; Make sure the docstring mentions the mode's hook.
296 "\n\nIn addition to any hooks its parent mode "
297 (if (string-match (regexp-quote (format "`%s'" parent))
299 (format "`%s' " parent))
300 "might have run,\nthis mode "))
301 (format "runs the hook `%s'" hook)
302 ", as the final step\nduring initialization.")))
304 (unless (or (string-match (regexp-quote "\\{") docstring)
305 (string-match (regexp-quote "\\[") docstring))
306 ;; And don't forget to put the mode's keymap.
307 (setq docstring (concat docstring "\n\n\\{" (symbol-name map) "}")))
313 ;; The functions below are only provided for backward compatibility with
314 ;; code byte-compiled with versions of derived.el prior to Emacs-21.
316 (defsubst derived-mode-setup-function-name (mode)
317 "Construct a setup-function name based on a MODE name."
318 (intern (concat (symbol-name mode) "-setup")))
321 ;; Utility functions for defining a derived mode.
323 ;; XEmacs -- don't autoload
324 (defun derived-mode-init-mode-variables (mode)
325 "Initialise variables for a new MODE.
326 Right now, if they don't already exist, set up a blank keymap, an
327 empty syntax table, and an empty abbrev table -- these will be merged
328 the first time the mode is used."
330 (if (boundp (derived-mode-map-name mode))
332 (eval `(defvar ,(derived-mode-map-name mode)
334 (make-sparse-keymap (derived-mode-map-name mode))
335 ,(format "Keymap for %s." mode)))
336 (put (derived-mode-map-name mode) 'derived-mode-unmerged t))
338 (if (boundp (derived-mode-syntax-table-name mode))
340 (eval `(defvar ,(derived-mode-syntax-table-name mode)
342 ;; Make a syntax table which doesn't specify anything
343 ;; for any char. Valid data will be merged in by
344 ;; derived-mode-merge-syntax-tables.
345 ;; (make-char-table 'syntax-table nil)
347 ,(format "Syntax table for %s." mode)))
348 (put (derived-mode-syntax-table-name mode) 'derived-mode-unmerged t))
350 (if (boundp (derived-mode-abbrev-table-name mode))
352 (eval `(defvar ,(derived-mode-abbrev-table-name mode)
354 (define-abbrev-table (derived-mode-abbrev-table-name mode) nil)
356 ,(format "Abbrev table for %s." mode)))))
358 ;; Utility functions for running a derived mode.
360 (defun derived-mode-set-keymap (mode)
361 "Set the keymap of the new MODE, maybe merging with the parent."
362 (let* ((map-name (derived-mode-map-name mode))
363 (new-map (eval map-name))
364 (old-map (current-local-map)))
366 (get map-name 'derived-mode-unmerged)
367 (derived-mode-merge-keymaps old-map new-map))
368 (put map-name 'derived-mode-unmerged nil)
369 (use-local-map new-map)))
371 (defun derived-mode-set-syntax-table (mode)
372 "Set the syntax table of the new MODE, maybe merging with the parent."
373 (let* ((table-name (derived-mode-syntax-table-name mode))
374 (old-table (syntax-table))
375 (new-table (eval table-name)))
376 (if (get table-name 'derived-mode-unmerged)
377 (derived-mode-merge-syntax-tables old-table new-table))
378 (put table-name 'derived-mode-unmerged nil)
379 (set-syntax-table new-table)))
381 (defun derived-mode-set-abbrev-table (mode)
382 "Set the abbrev table for MODE if it exists.
383 Always merge its parent into it, since the merge is non-destructive."
384 (let* ((table-name (derived-mode-abbrev-table-name mode))
385 (old-table local-abbrev-table)
386 (new-table (eval table-name)))
387 (derived-mode-merge-abbrev-tables old-table new-table)
388 (setq local-abbrev-table new-table)))
390 ;;;(defun derived-mode-run-setup-function (mode)
391 ;;; "Run the setup function if it exists."
393 ;;; (let ((fname (derived-mode-setup-function-name mode)))
394 ;;; (if (fboundp fname)
395 ;;; (funcall fname))))
397 (defun derived-mode-run-hooks (mode)
398 "Run the mode hook for MODE."
399 (let ((hooks-name (derived-mode-hook-name mode)))
400 (if (boundp hooks-name)
401 (run-hooks hooks-name))))
403 ;; Functions to merge maps and tables.
405 (defun derived-mode-merge-keymaps (old new)
406 "Merge an OLD keymap into a NEW one.
407 The old keymap is set to be the last cdr of the new one, so that there will
408 be automatic inheritance."
409 ;; XEmacs change. FSF 19.30 to 21.3 has a whole bunch of weird crap here
410 ;; for merging prefix keys and such. Hopefully none of this is
411 ;; necessary in XEmacs.
412 (set-keymap-parents new (list old)))
414 (defun derived-mode-merge-syntax-tables (old new)
415 "Merge an OLD syntax table into a NEW one.
416 Where the new table already has an entry, nothing is copied from the old one."
417 ;; XEmacs change: on the other hand, Emacs 21.3 just has
418 ;; (set-char-table-parent new old) here.
419 ;; We use map-char-table, not map-syntax-table, so we can explicitly
420 ;; check for inheritance.
422 #'(lambda (key value)
423 (let ((newval (get-range-char-table key new 'multi)))
424 (cond ((eq newval 'multi) ; OK, dive into the class hierarchy
426 #'(lambda (key1 value1)
427 (when (eq ?@ (char-syntax-from-code
428 (get-range-char-table key new ?@)))
429 (put-char-table key1 value new))
433 ((eq ?@ (char-syntax-from-code newval)) ;; class at once
434 (put-char-table key value new))))
438 ;; Merge an old abbrev table into a new one.
439 ;; This function requires internal knowledge of how abbrev tables work,
440 ;; presuming that they are obarrays with the abbrev as the symbol, the expansion
441 ;; as the value of the symbol, and the hook as the function definition.
442 (defun derived-mode-merge-abbrev-tables (old new)
446 (or (intern-soft (symbol-name symbol) new)
447 (define-abbrev new (symbol-name symbol)
448 (symbol-value symbol) (symbol-function symbol))))
453 ;;; derived.el ends here