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1 | ;;; help-mode.el --- `help-mode' used by *Help* buffers |
2 | ||
3 | ;; Copyright (C) 1985, 1986, 1993, 1994, 1998, 1999, 2000, 2001 | |
4 | ;; Free Software Foundation, Inc. | |
5 | ||
6 | ;; Maintainer: FSF | |
7 | ;; Keywords: help, internal | |
8 | ||
9 | ;; This file is part of GNU Emacs. | |
10 | ||
11 | ;; GNU Emacs is free software; you can redistribute it and/or modify | |
12 | ;; it under the terms of the GNU General Public License as published by | |
13 | ;; the Free Software Foundation; either version 2, or (at your option) | |
14 | ;; any later version. | |
15 | ||
16 | ;; GNU Emacs is distributed in the hope that it will be useful, | |
17 | ;; but WITHOUT ANY WARRANTY; without even the implied warranty of | |
18 | ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
19 | ;; GNU General Public License for more details. | |
20 | ||
21 | ;; You should have received a copy of the GNU General Public License | |
22 | ;; along with GNU Emacs; see the file COPYING. If not, write to the | |
23 | ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330, | |
24 | ;; Boston, MA 02111-1307, USA. | |
25 | ||
26 | ;;; Commentary: | |
27 | ||
28 | ;; Defines `help-mode', which is the mode used by *Help* buffers, and | |
29 | ;; associated support machinery, such as adding hyperlinks, etc., | |
30 | ||
31 | ;;; Code: | |
32 | ||
33 | (require 'button) | |
34 | (eval-when-compile (require 'view)) | |
35 | ||
36 | (defvar help-mode-map (make-sparse-keymap) | |
37 | "Keymap for help mode.") | |
38 | ||
39 | (set-keymap-parent help-mode-map button-buffer-map) | |
40 | ||
41 | (define-key help-mode-map "\C-c\C-b" 'help-go-back) | |
42 | (define-key help-mode-map "\C-c\C-c" 'help-follow) | |
43 | ;; Documentation only, since we use minor-mode-overriding-map-alist. | |
44 | (define-key help-mode-map "\r" 'help-follow) | |
45 | ||
46 | (defvar help-xref-stack nil | |
47 | "A stack of ways by which to return to help buffers after following xrefs. | |
48 | Used by `help-follow' and `help-xref-go-back'. | |
49 | An element looks like (POSITION FUNCTION ARGS...), where POSITION is | |
50 | `(POINT . BUFFER-NAME)'. | |
51 | To use the element, do (apply FUNCTION ARGS) then goto the point in | |
52 | the named buffer.") | |
53 | (put 'help-xref-stack 'permanent-local t) | |
54 | ||
55 | (defvar help-xref-stack-item nil | |
56 | "An item for `help-follow' in this buffer to push onto `help-xref-stack'. | |
57 | The format is (FUNCTION ARGS...).") | |
58 | (put 'help-xref-stack-item 'permanent-local t) | |
59 | ||
60 | (setq-default help-xref-stack nil help-xref-stack-item nil) | |
61 | ||
62 | ||
63 | \f | |
64 | ;; Button types used by help | |
65 | ||
66 | ;; Make some button types that all use the same naming conventions | |
67 | (dolist (help-type '("function" "variable" "face" | |
68 | "coding-system" "input-method" "character-set")) | |
69 | (define-button-type (intern (purecopy (concat "help-" help-type))) | |
70 | 'help-function (intern (concat "describe-" help-type)) | |
71 | 'help-echo (purecopy (concat "mouse-2, RET: describe this " help-type)) | |
72 | 'action #'help-button-action)) | |
73 | ||
74 | ;; make some more ideosyncratic button types | |
75 | ||
76 | (define-button-type 'help-symbol | |
77 | 'help-function #'help-xref-interned | |
78 | 'help-echo (purecopy "mouse-2, RET: describe this symbol") | |
79 | 'action #'help-button-action) | |
80 | ||
81 | (define-button-type 'help-back | |
82 | 'help-function #'help-xref-go-back | |
83 | 'help-echo (purecopy "mouse-2, RET: go back to previous help buffer") | |
84 | 'action #'help-button-action) | |
85 | ||
86 | (define-button-type 'help-info | |
87 | 'help-function #'info | |
88 | 'help-echo (purecopy"mouse-2, RET: read this Info node") | |
89 | 'action #'help-button-action) | |
90 | ||
91 | (define-button-type 'help-customize-variable | |
92 | 'help-function (lambda (v) | |
93 | (if help-xref-stack | |
94 | (pop help-xref-stack)) | |
95 | (customize-variable v)) | |
96 | 'help-echo (purecopy "mouse-2, RET: customize variable") | |
97 | 'action #'help-button-action) | |
98 | ||
99 | (define-button-type 'help-function-def | |
100 | 'help-function (lambda (fun file) | |
101 | (require 'find-func) | |
102 | ;; Don't use find-function-noselect because it follows | |
103 | ;; aliases (which fails for built-in functions). | |
104 | (let* ((location (find-function-search-for-symbol | |
105 | fun nil file))) | |
106 | (pop-to-buffer (car location)) | |
107 | (goto-char (cdr location)))) | |
108 | 'help-echo (purecopy "mouse-2, RET: find function's definition") | |
109 | 'action #'help-button-action) | |
110 | ||
111 | (define-button-type 'help-variable-def | |
112 | 'help-function (lambda (var &optional file) | |
113 | (let ((location | |
114 | (find-variable-noselect var file))) | |
115 | (pop-to-buffer (car location)) | |
116 | (goto-char (cdr location)))) | |
117 | 'help-echo (purecopy"mouse-2, RET: find variable's definition") | |
118 | 'action #'help-button-action) | |
119 | ||
120 | (defun help-button-action (button) | |
121 | "Call BUTTON's help function." | |
122 | (help-do-xref (button-start button) | |
123 | (button-get button 'help-function) | |
124 | (button-get button 'help-args))) | |
125 | ||
126 | \f | |
127 | ;;;###autoload | |
128 | (define-derived-mode help-mode nil "Help" | |
129 | "Major mode for viewing help text and navigating references in it. | |
130 | Entry to this mode runs the normal hook `help-mode-hook'. | |
131 | Commands: | |
132 | \\{help-mode-map}" | |
133 | (setq font-lock-defaults nil) ; font-lock would defeat xref | |
134 | (view-mode) | |
135 | (make-local-variable 'view-no-disable-on-exit) | |
136 | (setq view-no-disable-on-exit t)) | |
137 | ||
138 | ;;;###autoload | |
139 | (defun help-mode-setup () | |
140 | (help-mode) | |
141 | (setq buffer-read-only nil)) | |
142 | ||
143 | ;;;###autoload | |
144 | (defun help-mode-finish () | |
145 | (when (eq major-mode 'help-mode) | |
146 | ;; View mode's read-only status of existing *Help* buffer is lost | |
147 | ;; by with-output-to-temp-buffer. | |
148 | (toggle-read-only 1) | |
149 | (help-make-xrefs (current-buffer))) | |
150 | (setq view-return-to-alist | |
151 | (list (cons (selected-window) help-return-method)))) | |
152 | ||
153 | \f | |
154 | ;;; Grokking cross-reference information in doc strings and | |
155 | ;;; hyperlinking it. | |
156 | ||
157 | ;; This may have some scope for extension and the same or something | |
158 | ;; similar should be done for widget doc strings, which currently use | |
159 | ;; another mechanism. | |
160 | ||
161 | (defcustom help-highlight-p t | |
162 | "*If non-nil, `help-make-xrefs' highlight cross-references. | |
163 | Under a window system it highlights them with face defined by | |
164 | `help-highlight-face'." | |
165 | :group 'help | |
166 | :version "20.3" | |
167 | :type 'boolean) | |
168 | ||
169 | (defcustom help-highlight-face 'underline | |
170 | "Face used by `help-make-xrefs' to highlight cross-references. | |
171 | Must be previously-defined." | |
172 | :group 'help | |
173 | :version "20.3" | |
174 | :type 'face) | |
175 | ||
176 | (defvar help-back-label (purecopy "[back]") | |
177 | "Label to use by `help-make-xrefs' for the go-back reference.") | |
178 | ||
179 | (defconst help-xref-symbol-regexp | |
180 | (purecopy (concat "\\(\\<\\(\\(variable\\|option\\)\\|" | |
181 | "\\(function\\|command\\)\\|" | |
182 | "\\(face\\)\\|" | |
183 | "\\(symbol\\)\\|" | |
184 | "\\(source \\(?:code \\)?\\(?:of\\|for\\)\\)\\)\\s-+\\)?" | |
185 | ;; Note starting with word-syntax character: | |
186 | "`\\(\\sw\\(\\sw\\|\\s_\\)+\\)'")) | |
187 | "Regexp matching doc string references to symbols. | |
188 | ||
189 | The words preceding the quoted symbol can be used in doc strings to | |
190 | distinguish references to variables, functions and symbols.") | |
191 | ||
192 | (defconst help-xref-mule-regexp nil | |
193 | "Regexp matching doc string references to MULE-related keywords. | |
194 | ||
195 | It is usually nil, and is temporarily bound to an appropriate regexp | |
196 | when help commands related to multilingual environment (e.g., | |
197 | `describe-coding-system') are invoked.") | |
198 | ||
199 | ||
200 | (defconst help-xref-info-regexp | |
201 | (purecopy "\\<[Ii]nfo[ \t\n]+node[ \t\n]+`\\([^']+\\)'") | |
202 | "Regexp matching doc string references to an Info node.") | |
203 | ||
204 | ;;;###autoload | |
205 | (defun help-setup-xref (item interactive-p) | |
206 | "Invoked from commands using the \"*Help*\" buffer to install some xref info. | |
207 | ||
208 | ITEM is a (FUNCTION . ARGS) pair appropriate for recreating the help | |
209 | buffer after following a reference. INTERACTIVE-P is non-nil if the | |
210 | calling command was invoked interactively. In this case the stack of | |
211 | items for help buffer \"back\" buttons is cleared." | |
212 | (if interactive-p | |
213 | (setq help-xref-stack nil)) | |
214 | (setq help-xref-stack-item item)) | |
215 | ||
216 | (defvar help-xref-following nil | |
217 | "Non-nil when following a help cross-reference.") | |
218 | ||
219 | ;;;###autoload | |
220 | (defun help-make-xrefs (&optional buffer) | |
221 | "Parse and hyperlink documentation cross-references in the given BUFFER. | |
222 | ||
223 | Find cross-reference information in a buffer and, if | |
224 | `help-highlight-p' is non-nil, highlight it with face defined by | |
225 | `help-highlight-face'; activate such cross references for selection | |
226 | with `help-follow'. Cross-references have the canonical form `...' | |
227 | and the type of reference may be disambiguated by the preceding | |
228 | word(s) used in `help-xref-symbol-regexp'. | |
229 | ||
230 | If the variable `help-xref-mule-regexp' is non-nil, find also | |
231 | cross-reference information related to multilingual environment | |
232 | \(e.g., coding-systems). This variable is also used to disambiguate | |
233 | the type of reference as the same way as `help-xref-symbol-regexp'. | |
234 | ||
235 | A special reference `back' is made to return back through a stack of | |
236 | help buffers. Variable `help-back-label' specifies the text for | |
237 | that." | |
238 | (interactive "b") | |
239 | (save-excursion | |
240 | (set-buffer (or buffer (current-buffer))) | |
241 | (goto-char (point-min)) | |
242 | ;; Skip the header-type info, though it might be useful to parse | |
243 | ;; it at some stage (e.g. "function in `library'"). | |
244 | (forward-paragraph) | |
245 | (let ((old-modified (buffer-modified-p))) | |
246 | (let ((stab (syntax-table)) | |
247 | (case-fold-search t) | |
248 | (inhibit-read-only t)) | |
249 | (set-syntax-table emacs-lisp-mode-syntax-table) | |
250 | ;; The following should probably be abstracted out. | |
251 | (unwind-protect | |
252 | (progn | |
253 | ;; Info references | |
254 | (save-excursion | |
255 | (while (re-search-forward help-xref-info-regexp nil t) | |
256 | (let ((data (match-string 1))) | |
257 | (save-match-data | |
258 | (unless (string-match "^([^)]+)" data) | |
259 | (setq data (concat "(emacs)" data)))) | |
260 | (help-xref-button 1 'help-info data)))) | |
261 | ;; Mule related keywords. Do this before trying | |
262 | ;; `help-xref-symbol-regexp' because some of Mule | |
263 | ;; keywords have variable or function definitions. | |
264 | (if help-xref-mule-regexp | |
265 | (save-excursion | |
266 | (while (re-search-forward help-xref-mule-regexp nil t) | |
267 | (let* ((data (match-string 7)) | |
268 | (sym (intern-soft data))) | |
269 | (cond | |
270 | ((match-string 3) ; coding system | |
271 | (and sym (coding-system-p sym) | |
272 | (help-xref-button 6 'help-coding-system sym))) | |
273 | ((match-string 4) ; input method | |
274 | (and (assoc data input-method-alist) | |
275 | (help-xref-button 7 'help-input-method data))) | |
276 | ((or (match-string 5) (match-string 6)) ; charset | |
277 | (and sym (charsetp sym) | |
278 | (help-xref-button 7 'help-character-set sym))) | |
279 | ((assoc data input-method-alist) | |
280 | (help-xref-button 7 'help-character-set data)) | |
281 | ((and sym (coding-system-p sym)) | |
282 | (help-xref-button 7 'help-coding-system sym)) | |
283 | ((and sym (charsetp sym)) | |
284 | (help-xref-button 7 'help-character-set sym))))))) | |
285 | ;; Quoted symbols | |
286 | (save-excursion | |
287 | (while (re-search-forward help-xref-symbol-regexp nil t) | |
288 | (let* ((data (match-string 8)) | |
289 | (sym (intern-soft data))) | |
290 | (if sym | |
291 | (cond | |
292 | ((match-string 3) ; `variable' &c | |
293 | (and (boundp sym) ; `variable' doesn't ensure | |
294 | ; it's actually bound | |
295 | (help-xref-button 8 'help-variable sym))) | |
296 | ((match-string 4) ; `function' &c | |
297 | (and (fboundp sym) ; similarly | |
298 | (help-xref-button 8 'help-function sym))) | |
299 | ((match-string 5) ; `face' | |
300 | (and (facep sym) | |
301 | (help-xref-button 8 'help-face sym))) | |
302 | ((match-string 6)) ; nothing for `symbol' | |
303 | ((match-string 7) | |
304 | ;; this used: | |
305 | ;; #'(lambda (arg) | |
306 | ;; (let ((location | |
307 | ;; (find-function-noselect arg))) | |
308 | ;; (pop-to-buffer (car location)) | |
309 | ;; (goto-char (cdr location)))) | |
310 | (help-xref-button 8 'help-function-def sym)) | |
311 | ((and (boundp sym) (fboundp sym)) | |
312 | ;; We can't intuit whether to use the | |
313 | ;; variable or function doc -- supply both. | |
314 | (help-xref-button 8 'help-symbol sym)) | |
315 | ((boundp sym) | |
316 | (help-xref-button 8 'help-variable sym)) | |
317 | ((fboundp sym) | |
318 | (help-xref-button 8 'help-function sym)) | |
319 | ((facep sym) | |
320 | (help-xref-button 8 'help-face sym))))))) | |
321 | ;; An obvious case of a key substitution: | |
322 | (save-excursion | |
323 | (while (re-search-forward | |
324 | ;; Assume command name is only word characters | |
325 | ;; and dashes to get things like `use M-x foo.'. | |
326 | "\\<M-x\\s-+\\(\\sw\\(\\sw\\|-\\)+\\)" nil t) | |
327 | (let ((sym (intern-soft (match-string 1)))) | |
328 | (if (fboundp sym) | |
329 | (help-xref-button 1 'help-function sym))))) | |
330 | ;; Look for commands in whole keymap substitutions: | |
331 | (save-excursion | |
332 | ;; Make sure to find the first keymap. | |
333 | (goto-char (point-min)) | |
334 | ;; Find a header and the column at which the command | |
335 | ;; name will be found. | |
336 | (while (re-search-forward "^key +binding\n\\(-+ +\\)-+\n\n" | |
337 | nil t) | |
338 | (let ((col (- (match-end 1) (match-beginning 1)))) | |
339 | (while | |
340 | ;; Ignore single blank lines in table, but not | |
341 | ;; double ones, which should terminate it. | |
342 | (and (not (looking-at "\n\\s-*\n")) | |
343 | (progn | |
344 | (and (eolp) (forward-line)) | |
345 | (end-of-line) | |
346 | (skip-chars-backward "^\t\n") | |
347 | (if (and (>= (current-column) col) | |
348 | (looking-at "\\(\\sw\\|-\\)+$")) | |
349 | (let ((sym (intern-soft (match-string 0)))) | |
350 | (if (fboundp sym) | |
351 | (help-xref-button 0 'help-function sym)))) | |
352 | (zerop (forward-line))))))))) | |
353 | (set-syntax-table stab)) | |
354 | ;; Delete extraneous newlines at the end of the docstring | |
355 | (goto-char (point-max)) | |
356 | (while (and (not (bobp)) (bolp)) | |
357 | (delete-char -1)) | |
358 | ;; Make a back-reference in this buffer if appropriate. | |
359 | (when (and help-xref-following help-xref-stack) | |
360 | (insert "\n\n") | |
361 | (help-insert-xref-button help-back-label 'help-back | |
362 | (current-buffer)))) | |
363 | ;; View mode steals RET from us. | |
364 | (set (make-local-variable 'minor-mode-overriding-map-alist) | |
365 | (list (cons 'view-mode | |
366 | (let ((map (make-sparse-keymap))) | |
367 | (set-keymap-parent map view-mode-map) | |
368 | (define-key map "\r" 'help-follow) | |
369 | map)))) | |
370 | (set-buffer-modified-p old-modified)))) | |
371 | ||
372 | ;;;###autoload | |
373 | (defun help-xref-button (match-number type &rest args) | |
374 | "Make a hyperlink for cross-reference text previously matched. | |
375 | MATCH-NUMBER is the subexpression of interest in the last matched | |
376 | regexp. TYPE is the type of button to use. Any remaining arguments are | |
377 | passed to the button's help-function when it is invoked. | |
378 | See `help-make-xrefs'." | |
379 | ;; Don't mung properties we've added specially in some instances. | |
380 | (unless (button-at (match-beginning match-number)) | |
381 | (make-text-button (match-beginning match-number) | |
382 | (match-end match-number) | |
383 | 'type type 'help-args args))) | |
384 | ||
385 | ;;;###autoload | |
386 | (defun help-insert-xref-button (string type &rest args) | |
387 | "Insert STRING and make a hyperlink from cross-reference text on it. | |
388 | TYPE is the type of button to use. Any remaining arguments are passed | |
389 | to the button's help-function when it is invoked. | |
390 | See `help-make-xrefs'." | |
391 | (unless (button-at (point)) | |
392 | (insert-text-button string 'type type 'help-args args))) | |
393 | ||
394 | ;;;###autoload | |
395 | (defun help-xref-on-pp (from to) | |
396 | "Add xrefs for symbols in `pp's output between FROM and TO." | |
397 | (let ((ost (syntax-table))) | |
398 | (unwind-protect | |
399 | (save-excursion | |
400 | (save-restriction | |
401 | (set-syntax-table emacs-lisp-mode-syntax-table) | |
402 | (narrow-to-region from to) | |
403 | (goto-char (point-min)) | |
404 | (while (not (eobp)) | |
405 | (cond | |
406 | ((looking-at "\"") (forward-sexp 1)) | |
407 | ((looking-at "#<") (search-forward ">" nil 'move)) | |
408 | ((looking-at "\\(\\(\\sw\\|\\s_\\)+\\)") | |
409 | (let* ((sym (intern-soft (match-string 1))) | |
410 | (type (cond ((fboundp sym) 'help-function) | |
411 | ((or (memq sym '(t nil)) | |
412 | (keywordp sym)) | |
413 | nil) | |
414 | ((and sym (boundp sym)) | |
415 | 'help-variable)))) | |
416 | (when type (help-xref-button 1 type sym))) | |
417 | (goto-char (match-end 1))) | |
418 | (t (forward-char 1)))))) | |
419 | (set-syntax-table ost)))) | |
420 | ||
421 | \f | |
422 | ;; Additional functions for (re-)creating types of help buffers. | |
423 | (defun help-xref-interned (symbol) | |
424 | "Follow a hyperlink which appeared to be an arbitrary interned SYMBOL. | |
425 | ||
426 | Both variable and function documentation are extracted into a single | |
427 | help buffer." | |
428 | (let ((fdoc (when (fboundp symbol) (describe-function symbol))) | |
429 | (facedoc (when (facep symbol) (describe-face symbol)))) | |
430 | (when (or (boundp symbol) (not fdoc)) | |
431 | (describe-variable symbol) | |
432 | ;; We now have a help buffer on the variable. Insert the function | |
433 | ;; text before it. | |
434 | (when (or fdoc facedoc) | |
435 | (with-current-buffer "*Help*" | |
436 | (goto-char (point-min)) | |
437 | (let ((inhibit-read-only t)) | |
438 | (when fdoc | |
439 | (insert fdoc "\n\n")) | |
440 | (when facedoc | |
441 | (insert (make-string 30 ?-) "\n\n" (symbol-name symbol) | |
442 | " is also a " "face." "\n\n" facedoc "\n\n")) | |
443 | (insert (make-string 30 ?-) "\n\n" (symbol-name symbol) | |
444 | " is also a " "variable." "\n\n")) | |
445 | (help-setup-xref (list #'help-xref-interned symbol) nil)))))) | |
446 | ||
447 | \f | |
448 | ;;; Navigation/hyperlinking with xrefs | |
449 | ||
450 | (defun help-xref-go-back (buffer) | |
451 | "From BUFFER, go back to previous help buffer text using `help-xref-stack'." | |
452 | (let (item position method args) | |
453 | (with-current-buffer buffer | |
454 | (when help-xref-stack | |
455 | (setq help-xref-stack (cdr help-xref-stack)) ; due to help-follow | |
456 | (setq item (pop help-xref-stack) | |
457 | position (car item) | |
458 | method (cadr item) | |
459 | args (cddr item)))) | |
460 | (apply method args) | |
461 | ;; We assume that the buffer we just recreated has the saved name, | |
462 | ;; which might not always be true. | |
463 | (when (get-buffer (cdr position)) | |
464 | (with-current-buffer (cdr position) | |
465 | (goto-char (car position)))))) | |
466 | ||
467 | (defun help-go-back () | |
468 | "Invoke the [back] button (if any) in the Help mode buffer." | |
469 | (interactive) | |
470 | (let ((back-button (button-at (1- (point-max))))) | |
471 | (if back-button | |
472 | (button-activate back-button) | |
473 | (error "No [back] button")))) | |
474 | ||
475 | (defun help-do-xref (pos function args) | |
476 | "Call the help cross-reference function FUNCTION with args ARGS. | |
477 | Things are set up properly so that the resulting help-buffer has | |
478 | a proper [back] button." | |
479 | (setq help-xref-stack (cons (cons (cons pos (buffer-name)) | |
480 | help-xref-stack-item) | |
481 | help-xref-stack)) | |
482 | (setq help-xref-stack-item nil) | |
483 | ;; There is a reference at point. Follow it. | |
484 | (let ((help-xref-following t)) | |
485 | (apply function args))) | |
486 | ||
487 | (defun help-follow (&optional pos) | |
488 | "Follow cross-reference at POS, defaulting to point. | |
489 | ||
490 | For the cross-reference format, see `help-make-xrefs'." | |
491 | (interactive "d") | |
492 | (unless pos | |
493 | (setq pos (point))) | |
494 | (unless (push-button pos) | |
495 | ;; check if the symbol under point is a function or variable | |
496 | (let ((sym | |
497 | (intern | |
498 | (save-excursion | |
499 | (goto-char pos) (skip-syntax-backward "w_") | |
500 | (buffer-substring (point) | |
501 | (progn (skip-syntax-forward "w_") | |
502 | (point))))))) | |
503 | (when (or (boundp sym) (fboundp sym)) | |
504 | (help-do-xref pos #'help-xref-interned (list sym)))))) | |
505 | ||
506 | ||
507 | (provide 'help-mode) | |
508 | ||
509 | ;;; help-mode.el ends here | |
510 | ||
511 |