1;;; help-mode.el --- `help-mode' used by *Help* buffers 2 3;; Copyright (C) 1985, 1986, 1993, 1994, 1998, 1999, 2000, 2001, 2002, 4;; 2003, 2004, 2005, 2006, 2007 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., 51 Franklin Street, Fifth Floor, 24;; Boston, MA 02110-1301, 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(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 [mouse-2] 'help-follow-mouse) 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-symbol) 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. 49Used by `help-follow' and `help-xref-go-back'. 50An element looks like (POSITION FUNCTION ARGS...). 51To use the element, do (apply FUNCTION ARGS) then goto the point.") 52(put 'help-xref-stack 'permanent-local t) 53(make-variable-buffer-local 'help-xref-stack) 54 55(defvar help-xref-stack-item nil 56 "An item for `help-follow' in this buffer to push onto `help-xref-stack'. 57The format is (FUNCTION ARGS...).") 58(put 'help-xref-stack-item 'permanent-local t) 59(make-variable-buffer-local 'help-xref-stack-item) 60 61(setq-default help-xref-stack nil help-xref-stack-item nil) 62 63(defcustom help-mode-hook nil 64 "Hook run by `help-mode'." 65 :type 'hook 66 :group 'help) 67 68;; Button types used by help 69 70(define-button-type 'help-xref 71 'follow-link t 72 'action #'help-button-action) 73 74(defun help-button-action (button) 75 "Call BUTTON's help function." 76 (help-do-xref (button-start button) 77 (button-get button 'help-function) 78 (button-get button 'help-args))) 79 80;; These 6 calls to define-button-type were generated in a dolist 81;; loop, but that is bad because it means these button types don't 82;; have an easily found definition. 83 84(define-button-type 'help-function 85 :supertype 'help-xref 86 'help-function 'describe-function 87 'help-echo (purecopy "mouse-2, RET: describe this function")) 88 89(define-button-type 'help-variable 90 :supertype 'help-xref 91 'help-function 'describe-variable 92 'help-echo (purecopy "mouse-2, RET: describe this variable")) 93 94(define-button-type 'help-face 95 :supertype 'help-xref 96 'help-function 'describe-face 97 'help-echo (purecopy "mouse-2, RET: describe this face")) 98 99(define-button-type 'help-coding-system 100 :supertype 'help-xref 101 'help-function 'describe-coding-system 102 'help-echo (purecopy "mouse-2, RET: describe this coding system")) 103 104(define-button-type 'help-input-method 105 :supertype 'help-xref 106 'help-function 'describe-input-method 107 'help-echo (purecopy "mouse-2, RET: describe this input method")) 108 109(define-button-type 'help-character-set 110 :supertype 'help-xref 111 'help-function 'describe-character-set 112 'help-echo (purecopy "mouse-2, RET: describe this character set")) 113 114;; make some more ideosyncratic button types 115 116(define-button-type 'help-symbol 117 :supertype 'help-xref 118 'help-function #'help-xref-interned 119 'help-echo (purecopy "mouse-2, RET: describe this symbol")) 120 121(define-button-type 'help-back 122 :supertype 'help-xref 123 'help-function #'help-xref-go-back 124 'help-echo (purecopy "mouse-2, RET: go back to previous help buffer")) 125 126(define-button-type 'help-info 127 :supertype 'help-xref 128 'help-function #'info 129 'help-echo (purecopy "mouse-2, RET: read this Info node")) 130 131(define-button-type 'help-url 132 :supertype 'help-xref 133 'help-function #'browse-url 134 'help-echo (purecopy "mouse-2, RET: view this URL in a browser")) 135 136(define-button-type 'help-customize-variable 137 :supertype 'help-xref 138 'help-function (lambda (v) 139 (customize-variable v)) 140 'help-echo (purecopy "mouse-2, RET: customize variable")) 141 142(define-button-type 'help-customize-face 143 :supertype 'help-xref 144 'help-function (lambda (v) 145 (customize-face v)) 146 'help-echo (purecopy "mouse-2, RET: customize face")) 147 148(define-button-type 'help-function-def 149 :supertype 'help-xref 150 'help-function (lambda (fun file) 151 (require 'find-func) 152 (when (eq file 'C-source) 153 (setq file 154 (help-C-file-name (indirect-function fun) 'fun))) 155 ;; Don't use find-function-noselect because it follows 156 ;; aliases (which fails for built-in functions). 157 (let ((location 158 (find-function-search-for-symbol fun nil file))) 159 (pop-to-buffer (car location)) 160 (if (cdr location) 161 (goto-char (cdr location)) 162 (message "Unable to find location in file")))) 163 'help-echo (purecopy "mouse-2, RET: find function's definition")) 164 165(define-button-type 'help-variable-def 166 :supertype 'help-xref 167 'help-function (lambda (var &optional file) 168 (when (eq file 'C-source) 169 (setq file (help-C-file-name var 'var))) 170 (let ((location (find-variable-noselect var file))) 171 (pop-to-buffer (car location)) 172 (if (cdr location) 173 (goto-char (cdr location)) 174 (message "Unable to find location in file")))) 175 'help-echo (purecopy "mouse-2, RET: find variable's definition")) 176 177(define-button-type 'help-face-def 178 :supertype 'help-xref 179 'help-function (lambda (fun file) 180 (require 'find-func) 181 ;; Don't use find-function-noselect because it follows 182 ;; aliases (which fails for built-in functions). 183 (let ((location 184 (find-function-search-for-symbol fun 'defface file))) 185 (pop-to-buffer (car location)) 186 (if (cdr location) 187 (goto-char (cdr location)) 188 (message "Unable to find location in file")))) 189 'help-echo (purecopy "mouse-2, RET: find face's definition")) 190 191 192;;;###autoload 193(defun help-mode () 194 "Major mode for viewing help text and navigating references in it. 195Entry to this mode runs the normal hook `help-mode-hook'. 196Commands: 197\\{help-mode-map}" 198 (interactive) 199 (kill-all-local-variables) 200 (use-local-map help-mode-map) 201 (setq mode-name "Help") 202 (setq major-mode 'help-mode) 203 (view-mode) 204 (make-local-variable 'view-no-disable-on-exit) 205 (setq view-no-disable-on-exit t) 206 (setq view-exit-action (lambda (buffer) 207 (or (window-minibuffer-p (selected-window)) 208 (one-window-p t) 209 (delete-window)))) 210 (run-mode-hooks 'help-mode-hook)) 211 212;;;###autoload 213(defun help-mode-setup () 214 (help-mode) 215 (setq buffer-read-only nil)) 216 217;;;###autoload 218(defun help-mode-finish () 219 (let ((entry (assq (selected-window) view-return-to-alist))) 220 (if entry 221 ;; When entering Help mode from the Help window, 222 ;; such as by following a link, preserve the same 223 ;; meaning for the q command. 224 ;; (setcdr entry (cons (selected-window) help-return-method)) 225 nil 226 (setq view-return-to-alist 227 (cons (cons (selected-window) help-return-method) 228 view-return-to-alist)))) 229 (when (eq major-mode 'help-mode) 230 ;; View mode's read-only status of existing *Help* buffer is lost 231 ;; by with-output-to-temp-buffer. 232 (toggle-read-only 1) 233 (help-make-xrefs (current-buffer)))) 234 235;; Grokking cross-reference information in doc strings and 236;; hyperlinking it. 237 238;; This may have some scope for extension and the same or something 239;; similar should be done for widget doc strings, which currently use 240;; another mechanism. 241 242(defvar help-back-label (purecopy "[back]") 243 "Label to use by `help-make-xrefs' for the go-back reference.") 244 245(defconst help-xref-symbol-regexp 246 (purecopy (concat "\\(\\<\\(\\(variable\\|option\\)\\|" ; Link to var 247 "\\(function\\|command\\)\\|" ; Link to function 248 "\\(face\\)\\|" ; Link to face 249 "\\(symbol\\|program\\|property\\)\\|" ; Don't link 250 "\\(source \\(?:code \\)?\\(?:of\\|for\\)\\)\\)" 251 "[ \t\n]+\\)?" 252 ;; Note starting with word-syntax character: 253 "`\\(\\sw\\(\\sw\\|\\s_\\)+\\)'")) 254 "Regexp matching doc string references to symbols. 255 256The words preceding the quoted symbol can be used in doc strings to 257distinguish references to variables, functions and symbols.") 258 259(defvar help-xref-mule-regexp nil 260 "Regexp matching doc string references to MULE-related keywords. 261 262It is usually nil, and is temporarily bound to an appropriate regexp 263when help commands related to multilingual environment (e.g., 264`describe-coding-system') are invoked.") 265 266 267(defconst help-xref-info-regexp 268 (purecopy "\\<[Ii]nfo[ \t\n]+\\(node\\|anchor\\)[ \t\n]+`\\([^']+\\)'") 269 "Regexp matching doc string references to an Info node.") 270 271(defconst help-xref-url-regexp 272 (purecopy "\\<[Uu][Rr][Ll][ \t\n]+`\\([^']+\\)'") 273 "Regexp matching doc string references to a URL.") 274 275;;;###autoload 276(defun help-setup-xref (item interactive-p) 277 "Invoked from commands using the \"*Help*\" buffer to install some xref info. 278 279ITEM is a (FUNCTION . ARGS) pair appropriate for recreating the help 280buffer after following a reference. INTERACTIVE-P is non-nil if the 281calling command was invoked interactively. In this case the stack of 282items for help buffer \"back\" buttons is cleared. 283 284This should be called very early, before the output buffer is cleared, 285because we want to record the \"previous\" position of point so we can 286restore it properly when going back." 287 (with-current-buffer (help-buffer) 288 (when help-xref-stack-item 289 (push (cons (point) help-xref-stack-item) help-xref-stack)) 290 (when interactive-p 291 (let ((tail (nthcdr 10 help-xref-stack))) 292 ;; Truncate the stack. 293 (if tail (setcdr tail nil)))) 294 (setq help-xref-stack-item item))) 295 296(defvar help-xref-following nil 297 "Non-nil when following a help cross-reference.") 298 299(defun help-buffer () 300 (buffer-name ;for with-output-to-temp-buffer 301 (if help-xref-following 302 (current-buffer) 303 (get-buffer-create "*Help*")))) 304 305(defvar help-xref-override-view-map 306 (let ((map (make-sparse-keymap))) 307 (set-keymap-parent map view-mode-map) 308 (define-key map "\r" nil) 309 map) 310 "Replacement keymap for `view-mode' in help buffers.") 311 312;;;###autoload 313(defun help-make-xrefs (&optional buffer) 314 "Parse and hyperlink documentation cross-references in the given BUFFER. 315 316Find cross-reference information in a buffer and activate such cross 317references for selection with `help-follow'. Cross-references have 318the canonical form `...' and the type of reference may be 319disambiguated by the preceding word(s) used in 320`help-xref-symbol-regexp'. Faces only get cross-referenced if 321preceded or followed by the word `face'. Variables without 322variable documentation do not get cross-referenced, unless 323preceded by the word `variable' or `option'. 324 325If the variable `help-xref-mule-regexp' is non-nil, find also 326cross-reference information related to multilingual environment 327\(e.g., coding-systems). This variable is also used to disambiguate 328the type of reference as the same way as `help-xref-symbol-regexp'. 329 330A special reference `back' is made to return back through a stack of 331help buffers. Variable `help-back-label' specifies the text for 332that." 333 (interactive "b") 334 (save-excursion 335 (set-buffer (or buffer (current-buffer))) 336 (goto-char (point-min)) 337 ;; Skip the header-type info, though it might be useful to parse 338 ;; it at some stage (e.g. "function in `library'"). 339 (forward-paragraph) 340 (let ((old-modified (buffer-modified-p))) 341 (let ((stab (syntax-table)) 342 (case-fold-search t) 343 (inhibit-read-only t)) 344 (set-syntax-table emacs-lisp-mode-syntax-table) 345 ;; The following should probably be abstracted out. 346 (unwind-protect 347 (progn 348 ;; Info references 349 (save-excursion 350 (while (re-search-forward help-xref-info-regexp nil t) 351 (let ((data (match-string 2))) 352 (save-match-data 353 (unless (string-match "^([^)]+)" data) 354 (setq data (concat "(emacs)" data)))) 355 (help-xref-button 2 'help-info data)))) 356 ;; URLs 357 (save-excursion 358 (while (re-search-forward help-xref-url-regexp nil t) 359 (let ((data (match-string 1))) 360 (help-xref-button 1 'help-url data)))) 361 ;; Mule related keywords. Do this before trying 362 ;; `help-xref-symbol-regexp' because some of Mule 363 ;; keywords have variable or function definitions. 364 (if help-xref-mule-regexp 365 (save-excursion 366 (while (re-search-forward help-xref-mule-regexp nil t) 367 (let* ((data (match-string 7)) 368 (sym (intern-soft data))) 369 (cond 370 ((match-string 3) ; coding system 371 (and sym (coding-system-p sym) 372 (help-xref-button 6 'help-coding-system sym))) 373 ((match-string 4) ; input method 374 (and (assoc data input-method-alist) 375 (help-xref-button 7 'help-input-method data))) 376 ((or (match-string 5) (match-string 6)) ; charset 377 (and sym (charsetp sym) 378 (help-xref-button 7 'help-character-set sym))) 379 ((assoc data input-method-alist) 380 (help-xref-button 7 'help-character-set data)) 381 ((and sym (coding-system-p sym)) 382 (help-xref-button 7 'help-coding-system sym)) 383 ((and sym (charsetp sym)) 384 (help-xref-button 7 'help-character-set sym))))))) 385 ;; Quoted symbols 386 (save-excursion 387 (while (re-search-forward help-xref-symbol-regexp nil t) 388 (let* ((data (match-string 8)) 389 (sym (intern-soft data))) 390 (if sym 391 (cond 392 ((match-string 3) ; `variable' &c 393 (and (or (boundp sym) ; `variable' doesn't ensure 394 ; it's actually bound 395 (get sym 'variable-documentation)) 396 (help-xref-button 8 'help-variable sym))) 397 ((match-string 4) ; `function' &c 398 (and (fboundp sym) ; similarly 399 (help-xref-button 8 'help-function sym))) 400 ((match-string 5) ; `face' 401 (and (facep sym) 402 (help-xref-button 8 'help-face sym))) 403 ((match-string 6)) ; nothing for `symbol' 404 ((match-string 7) 405;;; this used: 406;;; #'(lambda (arg) 407;;; (let ((location 408;;; (find-function-noselect arg))) 409;;; (pop-to-buffer (car location)) 410;;; (goto-char (cdr location)))) 411 (help-xref-button 8 'help-function-def sym)) 412 ((and 413 (facep sym) 414 (save-match-data (looking-at "[ \t\n]+face\\W"))) 415 (help-xref-button 8 'help-face sym)) 416 ((and (or (boundp sym) 417 (get sym 'variable-documentation)) 418 (fboundp sym)) 419 ;; We can't intuit whether to use the 420 ;; variable or function doc -- supply both. 421 (help-xref-button 8 'help-symbol sym)) 422 ((and 423 (or (boundp sym) 424 (get sym 'variable-documentation)) 425 (or 426 (documentation-property 427 sym 'variable-documentation) 428 (condition-case nil 429 (documentation-property 430 (indirect-variable sym) 431 'variable-documentation) 432 (cyclic-variable-indirection nil)))) 433 (help-xref-button 8 'help-variable sym)) 434 ((fboundp sym) 435 (help-xref-button 8 'help-function sym))))))) 436 ;; An obvious case of a key substitution: 437 (save-excursion 438 (while (re-search-forward 439 ;; Assume command name is only word characters 440 ;; and dashes to get things like `use M-x foo.'. 441 "\\<M-x\\s-+\\(\\sw\\(\\sw\\|-\\)+\\)" nil t) 442 (let ((sym (intern-soft (match-string 1)))) 443 (if (fboundp sym) 444 (help-xref-button 1 'help-function sym))))) 445 ;; Look for commands in whole keymap substitutions: 446 (save-excursion 447 ;; Make sure to find the first keymap. 448 (goto-char (point-min)) 449 ;; Find a header and the column at which the command 450 ;; name will be found. 451 452 ;; If the keymap substitution isn't the last thing in 453 ;; the doc string, and if there is anything on the 454 ;; same line after it, this code won't recognize the end of it. 455 (while (re-search-forward "^key +binding\n\\(-+ +\\)-+\n\n" 456 nil t) 457 (let ((col (- (match-end 1) (match-beginning 1)))) 458 (while 459 (and (not (eobp)) 460 ;; Stop at a pair of blank lines. 461 (not (looking-at "\n\\s-*\n"))) 462 ;; Skip a single blank line. 463 (and (eolp) (forward-line)) 464 (end-of-line) 465 (skip-chars-backward "^\t\n") 466 (if (and (>= (current-column) col) 467 (looking-at "\\(\\sw\\|-\\)+$")) 468 (let ((sym (intern-soft (match-string 0)))) 469 (if (fboundp sym) 470 (help-xref-button 0 'help-function sym)))) 471 (forward-line)))))) 472 (set-syntax-table stab)) 473 ;; Delete extraneous newlines at the end of the docstring 474 (goto-char (point-max)) 475 (while (and (not (bobp)) (bolp)) 476 (delete-char -1)) 477 (insert "\n") 478 ;; Make a back-reference in this buffer if appropriate. 479 (when help-xref-stack 480 (insert "\n") 481 (help-insert-xref-button help-back-label 'help-back 482 (current-buffer)) 483 (insert "\n"))) 484 ;; View mode steals RET from us. 485 (set (make-local-variable 'minor-mode-overriding-map-alist) 486 (list (cons 'view-mode help-xref-override-view-map))) 487 (set-buffer-modified-p old-modified)))) 488 489;;;###autoload 490(defun help-xref-button (match-number type &rest args) 491 "Make a hyperlink for cross-reference text previously matched. 492MATCH-NUMBER is the subexpression of interest in the last matched 493regexp. TYPE is the type of button to use. Any remaining arguments are 494passed to the button's help-function when it is invoked. 495See `help-make-xrefs'." 496 ;; Don't mung properties we've added specially in some instances. 497 (unless (button-at (match-beginning match-number)) 498 (make-text-button (match-beginning match-number) 499 (match-end match-number) 500 'type type 'help-args args))) 501 502;;;###autoload 503(defun help-insert-xref-button (string type &rest args) 504 "Insert STRING and make a hyperlink from cross-reference text on it. 505TYPE is the type of button to use. Any remaining arguments are passed 506to the button's help-function when it is invoked. 507See `help-make-xrefs'." 508 (unless (button-at (point)) 509 (insert-text-button string 'type type 'help-args args))) 510 511;;;###autoload 512(defun help-xref-on-pp (from to) 513 "Add xrefs for symbols in `pp's output between FROM and TO." 514 (if (> (- to from) 5000) nil 515 (with-syntax-table emacs-lisp-mode-syntax-table 516 (save-excursion 517 (save-restriction 518 (narrow-to-region from to) 519 (goto-char (point-min)) 520 (condition-case nil 521 (while (not (eobp)) 522 (cond 523 ((looking-at "\"") (forward-sexp 1)) 524 ((looking-at "#<") (search-forward ">" nil 'move)) 525 ((looking-at "\\(\\(\\sw\\|\\s_\\)+\\)") 526 (let* ((sym (intern-soft (match-string 1))) 527 (type (cond ((fboundp sym) 'help-function) 528 ((or (memq sym '(t nil)) 529 (keywordp sym)) 530 nil) 531 ((and sym 532 (or (boundp sym) 533 (get sym 534 'variable-documentation))) 535 'help-variable)))) 536 (when type (help-xref-button 1 type sym))) 537 (goto-char (match-end 1))) 538 (t (forward-char 1)))) 539 (error nil))))))) 540 541 542;; Additional functions for (re-)creating types of help buffers. 543(defun help-xref-interned (symbol) 544 "Follow a hyperlink which appeared to be an arbitrary interned SYMBOL. 545Both variable, function and face documentation are extracted into a single 546help buffer." 547 (with-current-buffer (help-buffer) 548 ;; Push the previous item on the stack before clobbering the output buffer. 549 (help-setup-xref nil nil) 550 (let ((facedoc (when (facep symbol) 551 ;; Don't record the current entry in the stack. 552 (setq help-xref-stack-item nil) 553 (describe-face symbol))) 554 (fdoc (when (fboundp symbol) 555 ;; Don't record the current entry in the stack. 556 (setq help-xref-stack-item nil) 557 (describe-function symbol))) 558 (sdoc (when (or (boundp symbol) 559 (get symbol 'variable-documentation)) 560 ;; Don't record the current entry in the stack. 561 (setq help-xref-stack-item nil) 562 (describe-variable symbol)))) 563 (cond 564 (sdoc 565 ;; We now have a help buffer on the variable. 566 ;; Insert the function and face text before it. 567 (when (or fdoc facedoc) 568 (goto-char (point-min)) 569 (let ((inhibit-read-only t)) 570 (when fdoc 571 (insert fdoc "\n\n") 572 (when facedoc 573 (insert (make-string 30 ?-) "\n\n" (symbol-name symbol) 574 " is also a " "face." "\n\n"))) 575 (when facedoc 576 (insert facedoc "\n\n")) 577 (insert (make-string 30 ?-) "\n\n" (symbol-name symbol) 578 " is also a " "variable." "\n\n")) 579 ;; Don't record the `describe-variable' item in the stack. 580 (setq help-xref-stack-item nil) 581 (help-setup-xref (list #'help-xref-interned symbol) nil))) 582 (fdoc 583 ;; We now have a help buffer on the function. 584 ;; Insert face text before it. 585 (when facedoc 586 (goto-char (point-max)) 587 (let ((inhibit-read-only t)) 588 (insert "\n\n" (make-string 30 ?-) "\n\n" (symbol-name symbol) 589 " is also a " "face." "\n\n" facedoc)) 590 ;; Don't record the `describe-function' item in the stack. 591 (setq help-xref-stack-item nil) 592 (help-setup-xref (list #'help-xref-interned symbol) nil))))))) 593 594 595;; Navigation/hyperlinking with xrefs 596 597(defun help-xref-go-back (buffer) 598 "From BUFFER, go back to previous help buffer text using `help-xref-stack'." 599 (let (item position method args) 600 (with-current-buffer buffer 601 (when help-xref-stack 602 (setq item (pop help-xref-stack) 603 ;; Clear the current item so that it won't get pushed 604 ;; by the function we're about to call. TODO: We could also 605 ;; push it onto a "forward" stack and add a `forw' button. 606 help-xref-stack-item nil 607 position (car item) 608 method (cadr item) 609 args (cddr item)))) 610 (apply method args) 611 (with-current-buffer buffer 612 (if (get-buffer-window buffer) 613 (set-window-point (get-buffer-window buffer) position) 614 (goto-char position))))) 615 616(defun help-go-back () 617 "Go back to previous topic in this help buffer." 618 (interactive) 619 (if help-xref-stack 620 (help-xref-go-back (current-buffer)) 621 (error "No previous help buffer"))) 622 623(defun help-do-xref (pos function args) 624 "Call the help cross-reference function FUNCTION with args ARGS. 625Things are set up properly so that the resulting help-buffer has 626a proper [back] button." 627 ;; There is a reference at point. Follow it. 628 (let ((help-xref-following t)) 629 (apply function args))) 630 631;; The doc string is meant to explain what buttons do. 632(defun help-follow-mouse () 633 "Follow the cross-reference that you click on." 634 (interactive) 635 (error "No cross-reference here")) 636 637;; The doc string is meant to explain what buttons do. 638(defun help-follow () 639 "Follow cross-reference at point. 640 641For the cross-reference format, see `help-make-xrefs'." 642 (interactive) 643 (error "No cross-reference here")) 644 645(defun help-follow-symbol (&optional pos) 646 "In help buffer, show docs for symbol at POS, defaulting to point. 647Show all docs for that symbol as either a variable, function or face." 648 (interactive "d") 649 (unless pos 650 (setq pos (point))) 651 ;; check if the symbol under point is a function, variable or face 652 (let ((sym 653 (intern 654 (save-excursion 655 (goto-char pos) (skip-syntax-backward "w_") 656 (buffer-substring (point) 657 (progn (skip-syntax-forward "w_") 658 (point))))))) 659 (when (or (boundp sym) 660 (get sym 'variable-documentation) 661 (fboundp sym) (facep sym)) 662 (help-do-xref pos #'help-xref-interned (list sym))))) 663 664(defun help-insert-string (string) 665 "Insert STRING to the help buffer and install xref info for it. 666This function can be used to restore the old contents of the help buffer 667when going back to the previous topic in the xref stack. It is needed 668in case when it is impossible to recompute the old contents of the 669help buffer by other means." 670 (setq help-xref-stack-item (list #'help-insert-string string)) 671 (with-output-to-temp-buffer (help-buffer) 672 (insert string))) 673 674(provide 'help-mode) 675 676;; arch-tag: 850954ae-3725-4cb4-8e91-0bf6d52d6b0b 677;;; help-mode.el ends here 678