1;;; help.el --- help commands for Emacs 2 3;; Copyright (C) 1985, 1986, 1993, 1994 Free Software Foundation, Inc. 4 5;; Maintainer: FSF 6;; Keywords: help, internal 7 8;; This file is part of GNU Emacs. 9 10;; GNU Emacs is free software; you can redistribute it and/or modify 11;; it under the terms of the GNU General Public License as published by 12;; the Free Software Foundation; either version 2, or (at your option) 13;; any later version. 14 15;; GNU Emacs is distributed in the hope that it will be useful, 16;; but WITHOUT ANY WARRANTY; without even the implied warranty of 17;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 18;; GNU General Public License for more details. 19 20;; You should have received a copy of the GNU General Public License 21;; along with GNU Emacs; see the file COPYING. If not, write to 22;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. 23 24;;; Commentary: 25 26;; This code implements GNU Emac's on-line help system, the one invoked by 27;;`M-x help-for-help'. 28 29;;; Code: 30 31;; Get the macro make-help-screen when this is compiled, 32;; or run interpreted, but not when the compiled code is loaded. 33(eval-when-compile (require 'help-macro)) 34 35(defvar help-map (make-sparse-keymap) 36 "Keymap for characters following the Help key.") 37 38(define-key global-map (char-to-string help-char) 'help-command) 39(fset 'help-command help-map) 40 41(define-key help-map (char-to-string help-char) 'help-for-help) 42(define-key help-map "?" 'help-for-help) 43 44(define-key help-map "\C-c" 'describe-copying) 45(define-key help-map "\C-d" 'describe-distribution) 46(define-key help-map "\C-w" 'describe-no-warranty) 47(define-key help-map "\C-p" 'describe-project) 48(define-key help-map "a" 'command-apropos) 49 50(define-key help-map "b" 'describe-bindings) 51 52(define-key help-map "c" 'describe-key-briefly) 53(define-key help-map "k" 'describe-key) 54 55(define-key help-map "d" 'describe-function) 56(define-key help-map "f" 'describe-function) 57 58(define-key help-map "i" 'info) 59(define-key help-map "\C-f" 'Info-goto-emacs-command-node) 60(define-key help-map "\C-k" 'Info-goto-emacs-key-command-node) 61 62(define-key help-map "l" 'view-lossage) 63 64(define-key help-map "m" 'describe-mode) 65 66(define-key help-map "\C-n" 'view-emacs-news) 67(define-key help-map "n" 'view-emacs-news) 68 69(define-key help-map "p" 'finder-by-keyword) 70(autoload 'finder-by-keyword "finder") 71 72(define-key help-map "s" 'describe-syntax) 73 74(define-key help-map "t" 'help-with-tutorial) 75 76(define-key help-map "w" 'where-is) 77 78(define-key help-map "v" 'describe-variable) 79 80(define-key help-map "q" 'help-quit) 81 82(defun help-quit () 83 (interactive) 84 nil) 85 86(defun help-with-tutorial () 87 "Select the Emacs learn-by-doing tutorial." 88 (interactive) 89 (let ((file (expand-file-name "~/TUTORIAL"))) 90 (delete-other-windows) 91 (if (get-file-buffer file) 92 (switch-to-buffer (get-file-buffer file)) 93 (switch-to-buffer (create-file-buffer file)) 94 (setq buffer-file-name file) 95 (setq default-directory (expand-file-name "~/")) 96 (setq buffer-auto-save-file-name nil) 97 (insert-file-contents (expand-file-name "TUTORIAL" data-directory)) 98 (goto-char (point-min)) 99 (search-forward "\n<<") 100 (beginning-of-line) 101 (delete-region (point) (progn (end-of-line) (point))) 102 (let ((n (- (window-height (selected-window)) 103 (count-lines (point-min) (point)) 104 6))) 105 (if (< n 12) 106 (newline n) 107 ;; Some people get confused by the large gap. 108 (newline (/ n 2)) 109 (insert "[Middle of page left blank for didactic purposes. " 110 "Text continues below]") 111 (newline (- n (/ n 2))))) 112 (goto-char (point-min)) 113 (set-buffer-modified-p nil)))) 114 115(defun describe-key-briefly (key) 116 "Print the name of the function KEY invokes. KEY is a string." 117 (interactive "kDescribe key briefly: ") 118 ;; If this key seq ends with a down event, discard the 119 ;; following click or drag event. Otherwise that would 120 ;; erase the message. 121 (let ((type (aref key (1- (length key))))) 122 (if (listp type) (setq type (car type))) 123 (and (symbolp type) 124 (memq 'down (event-modifiers type)) 125 (read-event))) 126 (let ((defn (key-binding key))) 127 (if (or (null defn) (integerp defn)) 128 (message "%s is undefined" (key-description key)) 129 (message "%s runs the command %s" 130 (key-description key) 131 (if (symbolp defn) defn (prin1-to-string defn)))))) 132 133(defun print-help-return-message (&optional function) 134 "Display or return message saying how to restore windows after help command. 135Computes a message and applies the optional argument FUNCTION to it. 136If FUNCTION is nil, applies `message' to it, thus printing it." 137 (and (not (get-buffer-window standard-output)) 138 (funcall (or function 'message) 139 (concat 140 (substitute-command-keys 141 (if (one-window-p t) 142 (if pop-up-windows 143 "Type \\[delete-other-windows] to remove help window." 144 "Type \\[switch-to-buffer] RET to remove help window.") 145 "Type \\[switch-to-buffer-other-window] RET to restore the other window.")) 146 (substitute-command-keys 147 " \\[scroll-other-window] to scroll the help."))))) 148 149(defun describe-key (key) 150 "Display documentation of the function invoked by KEY. KEY is a string." 151 (interactive "kDescribe key: ") 152 ;; If this key seq ends with a down event, discard the 153 ;; following click or drag event. Otherwise that would 154 ;; erase the message. 155 (let ((type (aref key (1- (length key))))) 156 (if (listp type) (setq type (car type))) 157 (and (symbolp type) 158 (memq 'down (event-modifiers type)) 159 (read-event))) 160 (let ((defn (key-binding key))) 161 (if (or (null defn) (integerp defn)) 162 (message "%s is undefined" (key-description key)) 163 (with-output-to-temp-buffer "*Help*" 164 (prin1 defn) 165 (princ ":\n") 166 (if (documentation defn) 167 (princ (documentation defn)) 168 (princ "not documented")) 169 (print-help-return-message))))) 170 171(defun describe-mode () 172 "Display documentation of current major mode and minor modes. 173For this to work correctly for a minor mode, the mode's indicator variable 174\(listed in `minor-mode-alist') must also be a function whose documentation 175describes the minor mode." 176 (interactive) 177 (with-output-to-temp-buffer "*Help*" 178 (let ((minor-modes minor-mode-alist) 179 (locals (buffer-local-variables))) 180 (while minor-modes 181 (let* ((minor-mode (car (car minor-modes))) 182 (indicator (car (cdr (car minor-modes)))) 183 (local-binding (assq minor-mode locals))) 184 ;; Document a minor mode if it is listed in minor-mode-alist, 185 ;; bound locally in this buffer, non-nil, and has a function 186 ;; definition. 187 (if (and local-binding 188 (cdr local-binding) 189 (fboundp minor-mode)) 190 (let ((pretty-minor-mode minor-mode)) 191 (if (string-match "-mode$" (symbol-name minor-mode)) 192 (setq pretty-minor-mode 193 (capitalize 194 (substring (symbol-name minor-mode) 195 0 (match-beginning 0))))) 196 (while (and indicator (symbolp indicator)) 197 (setq indicator (symbol-value indicator))) 198 (princ (format "%s minor mode (indicator%s):\n" 199 pretty-minor-mode indicator)) 200 (princ (documentation minor-mode)) 201 (princ "\n\n")))) 202 (setq minor-modes (cdr minor-modes)))) 203 (princ mode-name) 204 (princ " mode:\n") 205 (princ (documentation major-mode)) 206 (print-help-return-message))) 207 208;; So keyboard macro definitions are documented correctly 209(fset 'defining-kbd-macro (symbol-function 'start-kbd-macro)) 210 211(defun describe-distribution () 212 "Display info on how to obtain the latest version of GNU Emacs." 213 (interactive) 214 (find-file-read-only 215 (expand-file-name "DISTRIB" data-directory))) 216 217(defun describe-copying () 218 "Display info on how you may redistribute copies of GNU Emacs." 219 (interactive) 220 (find-file-read-only 221 (expand-file-name "COPYING" data-directory)) 222 (goto-char (point-min))) 223 224(defun describe-project () 225 "Display info on the GNU project." 226 (interactive) 227 (find-file-read-only 228 (expand-file-name "GNU" data-directory)) 229 (goto-char (point-min))) 230 231(defun describe-no-warranty () 232 "Display info on all the kinds of warranty Emacs does NOT have." 233 (interactive) 234 (describe-copying) 235 (let (case-fold-search) 236 (search-forward "NO WARRANTY") 237 (recenter 0))) 238 239(defun describe-prefix-bindings () 240 "Describe the bindings of the prefix used to reach this command. 241The prefix described consists of all but the last event 242of the key sequence that ran this command." 243 (interactive) 244 (let* ((key (this-command-keys)) 245 (prefix (make-vector (1- (length key)) nil)) 246 i) 247 (setq i 0) 248 (while (< i (length prefix)) 249 (aset prefix i (aref key i)) 250 (setq i (1+ i))) 251 (describe-bindings prefix))) 252;; Make C-h after a prefix, when not specifically bound, 253;; run describe-prefix-bindings. 254(setq prefix-help-command 'describe-prefix-bindings) 255 256(defun view-emacs-news () 257 "Display info on recent changes to Emacs." 258 (interactive) 259 (find-file-read-only (expand-file-name "NEWS" data-directory))) 260 261(defun view-lossage () 262 "Display last 100 input keystrokes." 263 (interactive) 264 (with-output-to-temp-buffer "*Help*" 265 (princ (key-description (recent-keys))) 266 (save-excursion 267 (set-buffer standard-output) 268 (goto-char (point-min)) 269 (while (progn (move-to-column 50) (not (eobp))) 270 (search-forward " " nil t) 271 (insert "\n"))) 272 (print-help-return-message))) 273 274(defalias 'help 'help-for-help) 275(make-help-screen help-for-help 276 "a b c f C-f i k C-k l m n p s t v w C-c C-d C-n C-w, or ? for more help:" 277 "You have typed \\[help-command], the help character. Type a Help option: 278\(Use \\<help-map>\\[scroll-up] or \\[scroll-down] to scroll through this text. 279Type \\<help-map>\\[help-quit] to exit the Help command.) 280 281a command-apropos. Give a substring, and see a list of commands 282 (functions interactively callable) that contain 283 that substring. See also the apropos command. 284b describe-bindings. Display table of all key bindings. 285c describe-key-briefly. Type a command key sequence; 286 it prints the function name that sequence runs. 287f describe-function. Type a function name and get documentation of it. 288C-f Info-goto-emacs-command-node. Type a function name; 289 it takes you to the Info node for that command. 290i info. The info documentation reader. 291k describe-key. Type a command key sequence; 292 it displays the full documentation. 293C-k Info-goto-emacs-key-command-node. Type a command key sequence; 294 it takes you to the Info node for the command bound to that key. 295l view-lossage. Shows last 100 characters you typed. 296m describe-mode. Print documentation of current major mode, 297 which describes the commands peculiar to it. 298n view-emacs-news. Shows emacs news file. 299p finder-by-keyword. Find packages matching a given topic keyword. 300s describe-syntax. Display contents of syntax table, plus explanations 301t help-with-tutorial. Select the Emacs learn-by-doing tutorial. 302v describe-variable. Type name of a variable; 303 it displays the variable's documentation and value. 304w where-is. Type command name; it prints which keystrokes 305 invoke that command. 306C-c print Emacs copying permission (General Public License). 307C-d print Emacs ordering information. 308C-n print news of recent Emacs changes. 309C-p print information about the GNU project. 310C-w print information on absence of warranty for GNU Emacs." 311 help-map) 312 313;; Return a function which is called by the list containing point. 314;; If that gives no function, return a function whose name is around point. 315;; If that doesn't give a function, return nil. 316(defun function-called-at-point () 317 (or (condition-case () 318 (save-excursion 319 (save-restriction 320 (narrow-to-region (max (point-min) (- (point) 1000)) (point-max)) 321 (backward-up-list 1) 322 (forward-char 1) 323 (let (obj) 324 (setq obj (read (current-buffer))) 325 (and (symbolp obj) (fboundp obj) obj)))) 326 (error nil)) 327 (condition-case () 328 (save-excursion 329 (forward-sexp -1) 330 (skip-chars-forward "'") 331 (let ((obj (read (current-buffer)))) 332 (and (symbolp obj) (fboundp obj) obj))) 333 (error nil)))) 334 335(defun describe-function (function) 336 "Display the full documentation of FUNCTION (a symbol)." 337 (interactive 338 (let ((fn (function-called-at-point)) 339 (enable-recursive-minibuffers t) 340 val) 341 (setq val (completing-read (if fn 342 (format "Describe function (default %s): " fn) 343 "Describe function: ") 344 obarray 'fboundp t)) 345 (list (if (equal val "") 346 fn (intern val))))) 347 (with-output-to-temp-buffer "*Help*" 348 (prin1 function) 349 (princ ": ") 350 (let* ((def (symbol-function function)) 351 (beg (if (commandp def) "an interactive " "a "))) 352 (princ (cond ((or (stringp def) 353 (vectorp def)) 354 "a keyboard macro.") 355 ((subrp def) 356 (concat beg "built-in function.")) 357 ((byte-code-function-p def) 358 (concat beg "compiled Lisp function.")) 359 ((symbolp def) 360 (format "alias for `%s'." def)) 361 ((eq (car-safe def) 'lambda) 362 (concat beg "Lisp function.")) 363 ((eq (car-safe def) 'macro) 364 "a Lisp macro.") 365 ((eq (car-safe def) 'mocklisp) 366 "a mocklisp function.") 367 ((eq (car-safe def) 'autoload) 368 (format "%s autoloaded Lisp %s." 369 (if (commandp def) "an interactive" "an") 370 (if (nth 4 def) "macro" "function") 371;;; Including the file name made this line too long. 372;;; (nth 1 def) 373 )) 374 (t ""))) 375 (terpri) 376 (let ((arglist (cond ((byte-code-function-p def) 377 (car (append def nil))) 378 ((eq (car-safe def) 'lambda) 379 (nth 1 def)) 380 (t t)))) 381 (if (listp arglist) 382 (progn 383 (princ (cons function 384 (mapcar (lambda (arg) 385 (if (memq arg '(&optional &rest)) 386 arg 387 (intern (upcase (symbol-name arg))))) 388 arglist))) 389 (terpri)))) 390 (if (documentation function) 391 (progn (terpri) 392 (princ (documentation function))) 393 (princ "not documented")) 394 ) 395 (print-help-return-message) 396 ;; Return the text we displayed. 397 (save-excursion (set-buffer standard-output) (buffer-string)))) 398 399(defun variable-at-point () 400 (condition-case () 401 (save-excursion 402 (forward-sexp -1) 403 (skip-chars-forward "'") 404 (let ((obj (read (current-buffer)))) 405 (and (symbolp obj) (boundp obj) obj))) 406 (error nil))) 407 408(defun describe-variable (variable) 409 "Display the full documentation of VARIABLE (a symbol). 410Returns the documentation as a string, also." 411 (interactive 412 (let ((v (variable-at-point)) 413 (enable-recursive-minibuffers t) 414 val) 415 (setq val (completing-read (if v 416 (format "Describe variable (default %s): " v) 417 "Describe variable: ") 418 obarray 'boundp t)) 419 (list (if (equal val "") 420 v (intern val))))) 421 (with-output-to-temp-buffer "*Help*" 422 (prin1 variable) 423 (princ "'s value is ") 424 (if (not (boundp variable)) 425 (princ "void.") 426 (prin1 (symbol-value variable))) 427 (terpri) (terpri) 428 (princ "Documentation:") 429 (terpri) 430 (let ((doc (documentation-property variable 'variable-documentation))) 431 (if doc 432 (princ (substitute-command-keys doc)) 433 (princ "not documented as a variable."))) 434 (print-help-return-message) 435 ;; Return the text we displayed. 436 (save-excursion (set-buffer standard-output) (buffer-string)))) 437 438(defun where-is (definition) 439 "Print message listing key sequences that invoke specified command. 440Argument is a command definition, usually a symbol with a function definition." 441 (interactive 442 (let ((fn (function-called-at-point)) 443 (enable-recursive-minibuffers t) 444 val) 445 (setq val (completing-read (if fn 446 (format "Where is command (default %s): " fn) 447 "Where is command: ") 448 obarray 'fboundp t)) 449 (list (if (equal val "") 450 fn (intern val))))) 451 (let* ((keys (where-is-internal definition overriding-local-map nil nil)) 452 (keys1 (mapconcat 'key-description keys ", "))) 453 (if (> (length keys1) 0) 454 (message "%s is on %s" definition keys1) 455 (message "%s is not on any key" definition))) 456 nil) 457 458(defun command-apropos (string) 459 "Like apropos but lists only symbols that are names of commands 460\(interactively callable functions). Argument REGEXP is a regular expression 461that is matched against command symbol names. Returns list of symbols and 462documentation found." 463 (interactive "sCommand apropos (regexp): ") 464 (let ((message 465 (let ((standard-output (get-buffer-create "*Help*"))) 466 (print-help-return-message 'identity)))) 467 (if (apropos string t 'commandp) 468 (and message (message message))))) 469 470(defun locate-library (library &optional nosuffix) 471 "Show the full path name of Emacs library LIBRARY. 472This command searches the directories in `load-path' like `M-x load-library' 473to find the file that `M-x load-library RET LIBRARY RET' would load. 474Optional second arg NOSUFFIX non-nil means don't add suffixes `.elc' or `.el' 475to the specified name LIBRARY (a la calling `load' instead of `load-library')." 476 (interactive "sLocate library: ") 477 (catch 'answer 478 (mapcar 479 '(lambda (dir) 480 (mapcar 481 '(lambda (suf) 482 (let ((try (expand-file-name (concat library suf) dir))) 483 (and (file-readable-p try) 484 (null (file-directory-p try)) 485 (progn 486 (message "Library is file %s" try) 487 (throw 'answer try))))) 488 (if nosuffix '("") '(".elc" ".el" "")))) 489 load-path) 490 (message "No library %s in search path" library) 491 nil)) 492 493;;; help.el ends here 494