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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 | ||
89f5b33f | 41 | (define-key help-mode-map [mouse-2] 'help-follow-mouse) |
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42 | (define-key help-mode-map "\C-c\C-b" 'help-go-back) |
43 | (define-key help-mode-map "\C-c\C-c" 'help-follow) | |
44 | ;; Documentation only, since we use minor-mode-overriding-map-alist. | |
45 | (define-key help-mode-map "\r" 'help-follow) | |
46 | ||
47 | (defvar help-xref-stack nil | |
48 | "A stack of ways by which to return to help buffers after following xrefs. | |
49 | Used by `help-follow' and `help-xref-go-back'. | |
89f5b33f SM |
50 | An element looks like (POSITION FUNCTION ARGS...). |
51 | To use the element, do (apply FUNCTION ARGS) then goto the point.") | |
f4ed5b19 | 52 | (put 'help-xref-stack 'permanent-local t) |
89f5b33f | 53 | (make-variable-buffer-local 'help-xref-stack) |
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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) | |
89f5b33f | 59 | (make-variable-buffer-local 'help-xref-stack-item) |
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60 | |
61 | (setq-default help-xref-stack nil help-xref-stack-item nil) | |
62 | ||
1700f41d RS |
63 | (defcustom help-mode-hook nil |
64 | "Hook run by `help-mode'." | |
65 | :type 'hook | |
66 | :group 'help) | |
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67 | \f |
68 | ;; Button types used by help | |
69 | ||
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70 | (define-button-type 'help-xref |
71 | 'action #'help-button-action) | |
72 | ||
73 | (defun help-button-action (button) | |
74 | "Call BUTTON's help function." | |
75 | (help-do-xref (button-start button) | |
76 | (button-get button 'help-function) | |
77 | (button-get button 'help-args))) | |
78 | ||
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79 | ;; Make some button types that all use the same naming conventions |
80 | (dolist (help-type '("function" "variable" "face" | |
81 | "coding-system" "input-method" "character-set")) | |
82 | (define-button-type (intern (purecopy (concat "help-" help-type))) | |
6e881567 | 83 | :supertype 'help-xref |
f4ed5b19 | 84 | 'help-function (intern (concat "describe-" help-type)) |
6e881567 | 85 | 'help-echo (purecopy (concat "mouse-2, RET: describe this " help-type)))) |
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86 | |
87 | ;; make some more ideosyncratic button types | |
88 | ||
89 | (define-button-type 'help-symbol | |
6e881567 | 90 | :supertype 'help-xref |
f4ed5b19 | 91 | 'help-function #'help-xref-interned |
6e881567 | 92 | 'help-echo (purecopy "mouse-2, RET: describe this symbol")) |
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93 | |
94 | (define-button-type 'help-back | |
6e881567 | 95 | :supertype 'help-xref |
f4ed5b19 | 96 | 'help-function #'help-xref-go-back |
6e881567 | 97 | 'help-echo (purecopy "mouse-2, RET: go back to previous help buffer")) |
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98 | |
99 | (define-button-type 'help-info | |
6e881567 | 100 | :supertype 'help-xref |
f4ed5b19 | 101 | 'help-function #'info |
6e881567 | 102 | 'help-echo (purecopy"mouse-2, RET: read this Info node")) |
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103 | |
104 | (define-button-type 'help-customize-variable | |
6e881567 | 105 | :supertype 'help-xref |
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106 | 'help-function (lambda (v) |
107 | (if help-xref-stack | |
108 | (pop help-xref-stack)) | |
109 | (customize-variable v)) | |
6e881567 | 110 | 'help-echo (purecopy "mouse-2, RET: customize variable")) |
f4ed5b19 | 111 | |
07f904a3 | 112 | (define-button-type 'help-customize-face |
6e881567 | 113 | :supertype 'help-xref |
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114 | 'help-function (lambda (v) |
115 | (if help-xref-stack | |
116 | (pop help-xref-stack)) | |
117 | (customize-face v)) | |
6e881567 | 118 | 'help-echo (purecopy "mouse-2, RET: customize face")) |
07f904a3 | 119 | |
f4ed5b19 | 120 | (define-button-type 'help-function-def |
6e881567 | 121 | :supertype 'help-xref |
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122 | 'help-function (lambda (fun file) |
123 | (require 'find-func) | |
124 | ;; Don't use find-function-noselect because it follows | |
125 | ;; aliases (which fails for built-in functions). | |
126 | (let* ((location (find-function-search-for-symbol | |
127 | fun nil file))) | |
128 | (pop-to-buffer (car location)) | |
129 | (goto-char (cdr location)))) | |
6e881567 | 130 | 'help-echo (purecopy "mouse-2, RET: find function's definition")) |
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131 | |
132 | (define-button-type 'help-variable-def | |
6e881567 | 133 | :supertype 'help-xref |
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134 | 'help-function (lambda (var &optional file) |
135 | (let ((location | |
136 | (find-variable-noselect var file))) | |
137 | (pop-to-buffer (car location)) | |
138 | (goto-char (cdr location)))) | |
6e881567 | 139 | 'help-echo (purecopy"mouse-2, RET: find variable's definition")) |
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140 | |
141 | \f | |
142 | ;;;###autoload | |
1700f41d | 143 | (defun help-mode () |
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144 | "Major mode for viewing help text and navigating references in it. |
145 | Entry to this mode runs the normal hook `help-mode-hook'. | |
146 | Commands: | |
147 | \\{help-mode-map}" | |
1700f41d RS |
148 | (interactive) |
149 | (kill-all-local-variables) | |
150 | (use-local-map help-mode-map) | |
151 | (setq mode-name "Help") | |
152 | (setq major-mode 'help-mode) | |
153 | (make-local-variable 'font-lock-defaults) | |
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154 | (setq font-lock-defaults nil) ; font-lock would defeat xref |
155 | (view-mode) | |
156 | (make-local-variable 'view-no-disable-on-exit) | |
1700f41d RS |
157 | (setq view-no-disable-on-exit t) |
158 | (run-hooks 'help-mode-hook)) | |
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159 | |
160 | ;;;###autoload | |
161 | (defun help-mode-setup () | |
162 | (help-mode) | |
163 | (setq buffer-read-only nil)) | |
164 | ||
165 | ;;;###autoload | |
166 | (defun help-mode-finish () | |
167 | (when (eq major-mode 'help-mode) | |
168 | ;; View mode's read-only status of existing *Help* buffer is lost | |
169 | ;; by with-output-to-temp-buffer. | |
170 | (toggle-read-only 1) | |
171 | (help-make-xrefs (current-buffer))) | |
172 | (setq view-return-to-alist | |
173 | (list (cons (selected-window) help-return-method)))) | |
174 | ||
175 | \f | |
176 | ;;; Grokking cross-reference information in doc strings and | |
177 | ;;; hyperlinking it. | |
178 | ||
179 | ;; This may have some scope for extension and the same or something | |
180 | ;; similar should be done for widget doc strings, which currently use | |
181 | ;; another mechanism. | |
182 | ||
183 | (defcustom help-highlight-p t | |
184 | "*If non-nil, `help-make-xrefs' highlight cross-references. | |
185 | Under a window system it highlights them with face defined by | |
186 | `help-highlight-face'." | |
187 | :group 'help | |
188 | :version "20.3" | |
189 | :type 'boolean) | |
190 | ||
191 | (defcustom help-highlight-face 'underline | |
192 | "Face used by `help-make-xrefs' to highlight cross-references. | |
193 | Must be previously-defined." | |
194 | :group 'help | |
195 | :version "20.3" | |
196 | :type 'face) | |
197 | ||
198 | (defvar help-back-label (purecopy "[back]") | |
199 | "Label to use by `help-make-xrefs' for the go-back reference.") | |
200 | ||
201 | (defconst help-xref-symbol-regexp | |
202 | (purecopy (concat "\\(\\<\\(\\(variable\\|option\\)\\|" | |
203 | "\\(function\\|command\\)\\|" | |
204 | "\\(face\\)\\|" | |
205 | "\\(symbol\\)\\|" | |
206 | "\\(source \\(?:code \\)?\\(?:of\\|for\\)\\)\\)\\s-+\\)?" | |
207 | ;; Note starting with word-syntax character: | |
208 | "`\\(\\sw\\(\\sw\\|\\s_\\)+\\)'")) | |
209 | "Regexp matching doc string references to symbols. | |
210 | ||
211 | The words preceding the quoted symbol can be used in doc strings to | |
212 | distinguish references to variables, functions and symbols.") | |
213 | ||
214 | (defconst help-xref-mule-regexp nil | |
215 | "Regexp matching doc string references to MULE-related keywords. | |
216 | ||
217 | It is usually nil, and is temporarily bound to an appropriate regexp | |
218 | when help commands related to multilingual environment (e.g., | |
219 | `describe-coding-system') are invoked.") | |
220 | ||
221 | ||
222 | (defconst help-xref-info-regexp | |
223 | (purecopy "\\<[Ii]nfo[ \t\n]+node[ \t\n]+`\\([^']+\\)'") | |
224 | "Regexp matching doc string references to an Info node.") | |
225 | ||
226 | ;;;###autoload | |
227 | (defun help-setup-xref (item interactive-p) | |
228 | "Invoked from commands using the \"*Help*\" buffer to install some xref info. | |
229 | ||
230 | ITEM is a (FUNCTION . ARGS) pair appropriate for recreating the help | |
231 | buffer after following a reference. INTERACTIVE-P is non-nil if the | |
232 | calling command was invoked interactively. In this case the stack of | |
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233 | items for help buffer \"back\" buttons is cleared. |
234 | ||
235 | This should be called very early, before the output buffer is cleared, | |
236 | because we want to record the \"previous\" position of point so we can | |
237 | restore it properly when going back." | |
238 | (with-current-buffer (help-buffer) | |
239 | (if interactive-p | |
240 | ;; Why do we want to prevent the user from going back ?? -stef | |
241 | (setq help-xref-stack nil) | |
242 | (when help-xref-stack-item | |
243 | (push (cons (point) help-xref-stack-item) help-xref-stack))) | |
244 | (setq help-xref-stack-item item))) | |
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245 | |
246 | (defvar help-xref-following nil | |
247 | "Non-nil when following a help cross-reference.") | |
248 | ||
89f5b33f | 249 | (defun help-buffer () |
89f5b33f SM |
250 | (buffer-name ;for with-output-to-temp-buffer |
251 | (if help-xref-following | |
252 | (current-buffer) | |
253 | (get-buffer-create "*Help*")))) | |
254 | ||
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255 | ;;;###autoload |
256 | (defun help-make-xrefs (&optional buffer) | |
257 | "Parse and hyperlink documentation cross-references in the given BUFFER. | |
258 | ||
259 | Find cross-reference information in a buffer and, if | |
260 | `help-highlight-p' is non-nil, highlight it with face defined by | |
261 | `help-highlight-face'; activate such cross references for selection | |
262 | with `help-follow'. Cross-references have the canonical form `...' | |
263 | and the type of reference may be disambiguated by the preceding | |
264 | word(s) used in `help-xref-symbol-regexp'. | |
265 | ||
266 | If the variable `help-xref-mule-regexp' is non-nil, find also | |
267 | cross-reference information related to multilingual environment | |
268 | \(e.g., coding-systems). This variable is also used to disambiguate | |
269 | the type of reference as the same way as `help-xref-symbol-regexp'. | |
270 | ||
271 | A special reference `back' is made to return back through a stack of | |
272 | help buffers. Variable `help-back-label' specifies the text for | |
273 | that." | |
274 | (interactive "b") | |
275 | (save-excursion | |
276 | (set-buffer (or buffer (current-buffer))) | |
277 | (goto-char (point-min)) | |
278 | ;; Skip the header-type info, though it might be useful to parse | |
279 | ;; it at some stage (e.g. "function in `library'"). | |
280 | (forward-paragraph) | |
281 | (let ((old-modified (buffer-modified-p))) | |
282 | (let ((stab (syntax-table)) | |
283 | (case-fold-search t) | |
284 | (inhibit-read-only t)) | |
285 | (set-syntax-table emacs-lisp-mode-syntax-table) | |
286 | ;; The following should probably be abstracted out. | |
287 | (unwind-protect | |
288 | (progn | |
289 | ;; Info references | |
290 | (save-excursion | |
291 | (while (re-search-forward help-xref-info-regexp nil t) | |
292 | (let ((data (match-string 1))) | |
293 | (save-match-data | |
294 | (unless (string-match "^([^)]+)" data) | |
295 | (setq data (concat "(emacs)" data)))) | |
296 | (help-xref-button 1 'help-info data)))) | |
297 | ;; Mule related keywords. Do this before trying | |
298 | ;; `help-xref-symbol-regexp' because some of Mule | |
299 | ;; keywords have variable or function definitions. | |
300 | (if help-xref-mule-regexp | |
301 | (save-excursion | |
302 | (while (re-search-forward help-xref-mule-regexp nil t) | |
303 | (let* ((data (match-string 7)) | |
304 | (sym (intern-soft data))) | |
305 | (cond | |
306 | ((match-string 3) ; coding system | |
307 | (and sym (coding-system-p sym) | |
308 | (help-xref-button 6 'help-coding-system sym))) | |
309 | ((match-string 4) ; input method | |
310 | (and (assoc data input-method-alist) | |
311 | (help-xref-button 7 'help-input-method data))) | |
312 | ((or (match-string 5) (match-string 6)) ; charset | |
313 | (and sym (charsetp sym) | |
314 | (help-xref-button 7 'help-character-set sym))) | |
315 | ((assoc data input-method-alist) | |
316 | (help-xref-button 7 'help-character-set data)) | |
317 | ((and sym (coding-system-p sym)) | |
318 | (help-xref-button 7 'help-coding-system sym)) | |
319 | ((and sym (charsetp sym)) | |
320 | (help-xref-button 7 'help-character-set sym))))))) | |
321 | ;; Quoted symbols | |
322 | (save-excursion | |
323 | (while (re-search-forward help-xref-symbol-regexp nil t) | |
324 | (let* ((data (match-string 8)) | |
325 | (sym (intern-soft data))) | |
326 | (if sym | |
327 | (cond | |
328 | ((match-string 3) ; `variable' &c | |
329 | (and (boundp sym) ; `variable' doesn't ensure | |
330 | ; it's actually bound | |
331 | (help-xref-button 8 'help-variable sym))) | |
332 | ((match-string 4) ; `function' &c | |
333 | (and (fboundp sym) ; similarly | |
334 | (help-xref-button 8 'help-function sym))) | |
335 | ((match-string 5) ; `face' | |
336 | (and (facep sym) | |
337 | (help-xref-button 8 'help-face sym))) | |
338 | ((match-string 6)) ; nothing for `symbol' | |
339 | ((match-string 7) | |
340 | ;; this used: | |
341 | ;; #'(lambda (arg) | |
342 | ;; (let ((location | |
343 | ;; (find-function-noselect arg))) | |
344 | ;; (pop-to-buffer (car location)) | |
345 | ;; (goto-char (cdr location)))) | |
346 | (help-xref-button 8 'help-function-def sym)) | |
347 | ((and (boundp sym) (fboundp sym)) | |
348 | ;; We can't intuit whether to use the | |
349 | ;; variable or function doc -- supply both. | |
350 | (help-xref-button 8 'help-symbol sym)) | |
351 | ((boundp sym) | |
352 | (help-xref-button 8 'help-variable sym)) | |
353 | ((fboundp sym) | |
354 | (help-xref-button 8 'help-function sym)) | |
355 | ((facep sym) | |
356 | (help-xref-button 8 'help-face sym))))))) | |
357 | ;; An obvious case of a key substitution: | |
358 | (save-excursion | |
359 | (while (re-search-forward | |
360 | ;; Assume command name is only word characters | |
361 | ;; and dashes to get things like `use M-x foo.'. | |
362 | "\\<M-x\\s-+\\(\\sw\\(\\sw\\|-\\)+\\)" nil t) | |
363 | (let ((sym (intern-soft (match-string 1)))) | |
364 | (if (fboundp sym) | |
365 | (help-xref-button 1 'help-function sym))))) | |
366 | ;; Look for commands in whole keymap substitutions: | |
367 | (save-excursion | |
368 | ;; Make sure to find the first keymap. | |
369 | (goto-char (point-min)) | |
370 | ;; Find a header and the column at which the command | |
371 | ;; name will be found. | |
372 | (while (re-search-forward "^key +binding\n\\(-+ +\\)-+\n\n" | |
373 | nil t) | |
374 | (let ((col (- (match-end 1) (match-beginning 1)))) | |
375 | (while | |
376 | ;; Ignore single blank lines in table, but not | |
377 | ;; double ones, which should terminate it. | |
378 | (and (not (looking-at "\n\\s-*\n")) | |
379 | (progn | |
380 | (and (eolp) (forward-line)) | |
381 | (end-of-line) | |
382 | (skip-chars-backward "^\t\n") | |
383 | (if (and (>= (current-column) col) | |
384 | (looking-at "\\(\\sw\\|-\\)+$")) | |
385 | (let ((sym (intern-soft (match-string 0)))) | |
386 | (if (fboundp sym) | |
387 | (help-xref-button 0 'help-function sym)))) | |
388 | (zerop (forward-line))))))))) | |
389 | (set-syntax-table stab)) | |
390 | ;; Delete extraneous newlines at the end of the docstring | |
391 | (goto-char (point-max)) | |
392 | (while (and (not (bobp)) (bolp)) | |
393 | (delete-char -1)) | |
394 | ;; Make a back-reference in this buffer if appropriate. | |
89f5b33f | 395 | (when help-xref-stack |
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396 | (insert "\n\n") |
397 | (help-insert-xref-button help-back-label 'help-back | |
398 | (current-buffer)))) | |
399 | ;; View mode steals RET from us. | |
400 | (set (make-local-variable 'minor-mode-overriding-map-alist) | |
401 | (list (cons 'view-mode | |
402 | (let ((map (make-sparse-keymap))) | |
403 | (set-keymap-parent map view-mode-map) | |
404 | (define-key map "\r" 'help-follow) | |
405 | map)))) | |
406 | (set-buffer-modified-p old-modified)))) | |
407 | ||
408 | ;;;###autoload | |
409 | (defun help-xref-button (match-number type &rest args) | |
410 | "Make a hyperlink for cross-reference text previously matched. | |
411 | MATCH-NUMBER is the subexpression of interest in the last matched | |
412 | regexp. TYPE is the type of button to use. Any remaining arguments are | |
413 | passed to the button's help-function when it is invoked. | |
414 | See `help-make-xrefs'." | |
415 | ;; Don't mung properties we've added specially in some instances. | |
416 | (unless (button-at (match-beginning match-number)) | |
417 | (make-text-button (match-beginning match-number) | |
418 | (match-end match-number) | |
419 | 'type type 'help-args args))) | |
420 | ||
421 | ;;;###autoload | |
422 | (defun help-insert-xref-button (string type &rest args) | |
423 | "Insert STRING and make a hyperlink from cross-reference text on it. | |
424 | TYPE is the type of button to use. Any remaining arguments are passed | |
425 | to the button's help-function when it is invoked. | |
426 | See `help-make-xrefs'." | |
427 | (unless (button-at (point)) | |
428 | (insert-text-button string 'type type 'help-args args))) | |
429 | ||
430 | ;;;###autoload | |
431 | (defun help-xref-on-pp (from to) | |
432 | "Add xrefs for symbols in `pp's output between FROM and TO." | |
433 | (let ((ost (syntax-table))) | |
434 | (unwind-protect | |
435 | (save-excursion | |
436 | (save-restriction | |
437 | (set-syntax-table emacs-lisp-mode-syntax-table) | |
438 | (narrow-to-region from to) | |
439 | (goto-char (point-min)) | |
440 | (while (not (eobp)) | |
441 | (cond | |
442 | ((looking-at "\"") (forward-sexp 1)) | |
443 | ((looking-at "#<") (search-forward ">" nil 'move)) | |
444 | ((looking-at "\\(\\(\\sw\\|\\s_\\)+\\)") | |
445 | (let* ((sym (intern-soft (match-string 1))) | |
446 | (type (cond ((fboundp sym) 'help-function) | |
447 | ((or (memq sym '(t nil)) | |
448 | (keywordp sym)) | |
449 | nil) | |
450 | ((and sym (boundp sym)) | |
451 | 'help-variable)))) | |
452 | (when type (help-xref-button 1 type sym))) | |
453 | (goto-char (match-end 1))) | |
454 | (t (forward-char 1)))))) | |
455 | (set-syntax-table ost)))) | |
456 | ||
457 | \f | |
458 | ;; Additional functions for (re-)creating types of help buffers. | |
459 | (defun help-xref-interned (symbol) | |
460 | "Follow a hyperlink which appeared to be an arbitrary interned SYMBOL. | |
89f5b33f | 461 | Both variable, function and face documentation are extracted into a single |
f4ed5b19 | 462 | help buffer." |
89f5b33f SM |
463 | (with-current-buffer (help-buffer) |
464 | ;; Push the previous item on the stack before clobbering the output buffer. | |
465 | (help-setup-xref nil nil) | |
466 | (let ((facedoc (when (facep symbol) | |
467 | ;; Don't record the current entry in the stack. | |
468 | (setq help-xref-stack-item nil) | |
469 | (describe-face symbol))) | |
470 | (fdoc (when (fboundp symbol) | |
471 | ;; Don't record the current entry in the stack. | |
472 | (setq help-xref-stack-item nil) | |
473 | (describe-function symbol))) | |
474 | (sdoc (when (boundp symbol) | |
475 | ;; Don't record the current entry in the stack. | |
476 | (setq help-xref-stack-item nil) | |
477 | (describe-variable symbol)))) | |
478 | (cond | |
479 | (sdoc | |
480 | ;; We now have a help buffer on the variable. | |
481 | ;; Insert the function and face text before it. | |
f4ed5b19 | 482 | (when (or fdoc facedoc) |
f4ed5b19 MB |
483 | (goto-char (point-min)) |
484 | (let ((inhibit-read-only t)) | |
485 | (when fdoc | |
89f5b33f | 486 | (insert fdoc "\n\n") |
f4ed5b19 MB |
487 | (when facedoc |
488 | (insert (make-string 30 ?-) "\n\n" (symbol-name symbol) | |
89f5b33f SM |
489 | " is also a " "face." "\n\n"))) |
490 | (when facedoc | |
491 | (insert facedoc "\n\n")) | |
f4ed5b19 MB |
492 | (insert (make-string 30 ?-) "\n\n" (symbol-name symbol) |
493 | " is also a " "variable." "\n\n")) | |
89f5b33f SM |
494 | ;; Don't record the `describe-variable' item in the stack. |
495 | (setq help-xref-stack-item nil) | |
496 | (help-setup-xref (list #'help-xref-interned symbol) nil))) | |
497 | (fdoc | |
498 | ;; We now have a help buffer on the function. | |
499 | ;; Insert face text before it. | |
500 | (when facedoc | |
501 | (goto-char (point-max)) | |
502 | (let ((inhibit-read-only t)) | |
503 | (insert "\n\n" (make-string 30 ?-) "\n\n" (symbol-name symbol) | |
504 | " is also a " "face." "\n\n" facedoc)) | |
505 | ;; Don't record the `describe-function' item in the stack. | |
506 | (setq help-xref-stack-item nil) | |
507 | (help-setup-xref (list #'help-xref-interned symbol) nil))))))) | |
f4ed5b19 MB |
508 | |
509 | \f | |
510 | ;;; Navigation/hyperlinking with xrefs | |
511 | ||
89f5b33f SM |
512 | (defun help-follow-mouse (click) |
513 | "Follow the cross-reference that you CLICK on." | |
514 | (interactive "e") | |
515 | (let* ((start (event-start click)) | |
516 | (window (car start)) | |
517 | (pos (car (cdr start)))) | |
518 | (with-current-buffer (window-buffer window) | |
519 | (help-follow pos)))) | |
520 | ||
f4ed5b19 MB |
521 | (defun help-xref-go-back (buffer) |
522 | "From BUFFER, go back to previous help buffer text using `help-xref-stack'." | |
523 | (let (item position method args) | |
524 | (with-current-buffer buffer | |
525 | (when help-xref-stack | |
f4ed5b19 | 526 | (setq item (pop help-xref-stack) |
89f5b33f SM |
527 | ;; Clear the current item so that it won't get pushed |
528 | ;; by the function we're about to call. TODO: We could also | |
529 | ;; push it onto a "forward" stack and add a `forw' button. | |
530 | help-xref-stack-item nil | |
f4ed5b19 MB |
531 | position (car item) |
532 | method (cadr item) | |
533 | args (cddr item)))) | |
534 | (apply method args) | |
89f5b33f SM |
535 | ;; FIXME: are we sure we're in the right buffer ? |
536 | (goto-char position))) | |
f4ed5b19 MB |
537 | |
538 | (defun help-go-back () | |
539 | "Invoke the [back] button (if any) in the Help mode buffer." | |
540 | (interactive) | |
541 | (let ((back-button (button-at (1- (point-max))))) | |
542 | (if back-button | |
543 | (button-activate back-button) | |
544 | (error "No [back] button")))) | |
545 | ||
546 | (defun help-do-xref (pos function args) | |
547 | "Call the help cross-reference function FUNCTION with args ARGS. | |
548 | Things are set up properly so that the resulting help-buffer has | |
549 | a proper [back] button." | |
f4ed5b19 MB |
550 | ;; There is a reference at point. Follow it. |
551 | (let ((help-xref-following t)) | |
552 | (apply function args))) | |
553 | ||
554 | (defun help-follow (&optional pos) | |
555 | "Follow cross-reference at POS, defaulting to point. | |
556 | ||
557 | For the cross-reference format, see `help-make-xrefs'." | |
558 | (interactive "d") | |
559 | (unless pos | |
560 | (setq pos (point))) | |
561 | (unless (push-button pos) | |
562 | ;; check if the symbol under point is a function or variable | |
563 | (let ((sym | |
564 | (intern | |
565 | (save-excursion | |
566 | (goto-char pos) (skip-syntax-backward "w_") | |
567 | (buffer-substring (point) | |
568 | (progn (skip-syntax-forward "w_") | |
569 | (point))))))) | |
89f5b33f | 570 | (when (or (boundp sym) (fboundp sym) (facep sym)) |
f4ed5b19 MB |
571 | (help-do-xref pos #'help-xref-interned (list sym)))))) |
572 | ||
573 | ||
574 | (provide 'help-mode) | |
575 | ||
576 | ;;; help-mode.el ends here | |
577 | ||
578 |