1;;; eldoc.el --- show function arglist or variable docstring in echo area 2 3;; Copyright (C) 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 4;; 2005, 2006, 2007 Free Software Foundation, Inc. 5 6;; Author: Noah Friedman <friedman@splode.com> 7;; Maintainer: friedman@splode.com 8;; Keywords: extensions 9;; Created: 1995-10-06 10 11;; This file is part of GNU Emacs. 12 13;; GNU Emacs is free software; you can redistribute it and/or modify 14;; it under the terms of the GNU General Public License as published by 15;; the Free Software Foundation; either version 2, or (at your option) 16;; any later version. 17 18;; GNU Emacs is distributed in the hope that it will be useful, 19;; but WITHOUT ANY WARRANTY; without even the implied warranty of 20;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 21;; GNU General Public License for more details. 22 23;; You should have received a copy of the GNU General Public License 24;; along with GNU Emacs; see the file COPYING. If not, write to the 25;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, 26;; Boston, MA 02110-1301, USA. 27 28;;; Commentary: 29 30;; This program was inspired by the behavior of the "mouse documentation 31;; window" on many Lisp Machine systems; as you type a function's symbol 32;; name as part of a sexp, it will print the argument list for that 33;; function. Behavior is not identical; for example, you need not actually 34;; type the function name, you need only move point around in a sexp that 35;; calls it. Also, if point is over a documented variable, it will print 36;; the one-line documentation for that variable instead, to remind you of 37;; that variable's meaning. 38 39;; One useful way to enable this minor mode is to put the following in your 40;; .emacs: 41;; 42;; (add-hook 'emacs-lisp-mode-hook 'turn-on-eldoc-mode) 43;; (add-hook 'lisp-interaction-mode-hook 'turn-on-eldoc-mode) 44;; (add-hook 'ielm-mode-hook 'turn-on-eldoc-mode) 45 46;; Major modes for other languages may use Eldoc by defining an 47;; appropriate function as the buffer-local value of 48;; `eldoc-documentation-function'. 49 50;;; Code: 51 52(require 'help-fns) ;For fundoc-usage handling functions. 53 54(defgroup eldoc nil 55 "Show function arglist or variable docstring in echo area." 56 :group 'lisp 57 :group 'extensions) 58 59(defcustom eldoc-idle-delay 0.50 60 "*Number of seconds of idle time to wait before printing. 61If user input arrives before this interval of time has elapsed after the 62last input, no documentation will be printed. 63 64If this variable is set to 0, no idle time is required." 65 :type 'number 66 :group 'eldoc) 67 68;;;###autoload 69(defcustom eldoc-minor-mode-string " ElDoc" 70 "*String to display in mode line when Eldoc Mode is enabled; nil for none." 71 :type '(choice string (const :tag "None" nil)) 72 :group 'eldoc) 73 74(defcustom eldoc-argument-case 'upcase 75 "Case to display argument names of functions, as a symbol. 76This has two preferred values: `upcase' or `downcase'. 77Actually, any name of a function which takes a string as an argument and 78returns another string is acceptable." 79 :type '(radio (function-item upcase) 80 (function-item downcase) 81 function) 82 :group 'eldoc) 83 84(defcustom eldoc-echo-area-use-multiline-p 'truncate-sym-name-if-fit 85 "*Allow long eldoc messages to resize echo area display. 86If value is t, never attempt to truncate messages; complete symbol name 87and function arglist or 1-line variable documentation will be displayed 88even if echo area must be resized to fit. 89 90If value is any non-nil value other than t, symbol name may be truncated 91if it will enable the function arglist or documentation string to fit on a 92single line without resizing window. Otherwise, behavior is just like 93former case. 94 95If value is nil, messages are always truncated to fit in a single line of 96display in the echo area. Function or variable symbol name may be 97truncated to make more of the arglist or documentation string visible." 98 :type '(radio (const :tag "Always" t) 99 (const :tag "Never" nil) 100 (const :tag "Yes, but truncate symbol names if it will\ 101 enable argument list to fit on one line" truncate-sym-name-if-fit)) 102 :group 'eldoc) 103 104;;; No user options below here. 105 106(defvar eldoc-message-commands-table-size 31 107 "This is used by eldoc-add-command to initialize eldoc-message-commands 108as an obarray. 109It should probably never be necessary to do so, but if you 110choose to increase the number of buckets, you must do so before loading 111this file since the obarray is initialized at load time. 112Remember to keep it a prime number to improve hash performance.") 113 114(defconst eldoc-message-commands 115 (make-vector eldoc-message-commands-table-size 0) 116 "Commands after which it is appropriate to print in the echo area. 117Eldoc does not try to print function arglists, etc. after just any command, 118because some commands print their own messages in the echo area and these 119functions would instantly overwrite them. But self-insert-command as well 120as most motion commands are good candidates. 121This variable contains an obarray of symbols; do not manipulate it 122directly. Instead, use `eldoc-add-command' and `eldoc-remove-command'.") 123 124(defconst eldoc-last-data (make-vector 3 nil) 125 "Bookkeeping; elements are as follows: 126 0 - contains the last symbol read from the buffer. 127 1 - contains the string last displayed in the echo area for that 128 symbol, so it can be printed again if necessary without reconsing. 129 2 - 'function if function args, 'variable if variable documentation.") 130(defvar eldoc-last-message nil) 131 132(defvar eldoc-timer nil "eldoc's timer object.") 133 134(defvar eldoc-current-idle-delay eldoc-idle-delay 135 "idle time delay currently in use by timer. 136This is used to determine if `eldoc-idle-delay' is changed by the user.") 137 138 139;;;###autoload 140(define-minor-mode eldoc-mode 141 "Toggle ElDoc mode on or off. 142In ElDoc mode, the echo area displays information about a 143function or variable in the text where point is. If point is 144on a documented variable, it displays the first line of that 145variable's doc string. Otherwise it displays the argument list 146of the function called in the expression point is on. 147 148With prefix ARG, turn ElDoc mode on if and only if ARG is positive." 149 :group 'eldoc :lighter eldoc-minor-mode-string 150 (setq eldoc-last-message nil) 151 (if eldoc-mode 152 (progn 153 (add-hook 'post-command-hook 'eldoc-schedule-timer nil t) 154 (add-hook 'pre-command-hook 'eldoc-pre-command-refresh-echo-area t)) 155 (remove-hook 'post-command-hook 'eldoc-schedule-timer) 156 (remove-hook 'pre-command-hook 'eldoc-pre-command-refresh-echo-area))) 157 158;;;###autoload 159(defun turn-on-eldoc-mode () 160 "Unequivocally turn on ElDoc mode (see command `eldoc-mode')." 161 (interactive) 162 (eldoc-mode 1)) 163 164 165(defun eldoc-schedule-timer () 166 (or (and eldoc-timer 167 (memq eldoc-timer timer-idle-list)) 168 (setq eldoc-timer 169 (run-with-idle-timer eldoc-idle-delay t 170 'eldoc-print-current-symbol-info))) 171 172 ;; If user has changed the idle delay, update the timer. 173 (cond ((not (= eldoc-idle-delay eldoc-current-idle-delay)) 174 (setq eldoc-current-idle-delay eldoc-idle-delay) 175 (timer-set-idle-time eldoc-timer eldoc-idle-delay t)))) 176 177(defun eldoc-message (&rest args) 178 (let ((omessage eldoc-last-message)) 179 (setq eldoc-last-message 180 (cond ((eq (car args) eldoc-last-message) eldoc-last-message) 181 ((null (car args)) nil) 182 ;; If only one arg, no formatting to do, so put it in 183 ;; eldoc-last-message so eq test above might succeed on 184 ;; subsequent calls. 185 ((null (cdr args)) (car args)) 186 (t (apply 'format args)))) 187 ;; In emacs 19.29 and later, and XEmacs 19.13 and later, all messages 188 ;; are recorded in a log. Do not put eldoc messages in that log since 189 ;; they are Legion. 190 ;; Emacs way of preventing log messages. 191 (let ((message-log-max nil)) 192 (cond (eldoc-last-message (message "%s" eldoc-last-message)) 193 (omessage (message nil))))) 194 eldoc-last-message) 195 196;; This function goes on pre-command-hook for XEmacs or when using idle 197;; timers in Emacs. Motion commands clear the echo area for some reason, 198;; which make eldoc messages flicker or disappear just before motion 199;; begins. This function reprints the last eldoc message immediately 200;; before the next command executes, which does away with the flicker. 201;; This doesn't seem to be required for Emacs 19.28 and earlier. 202(defun eldoc-pre-command-refresh-echo-area () 203 (and eldoc-last-message 204 (if (eldoc-display-message-no-interference-p) 205 (eldoc-message eldoc-last-message) 206 (setq eldoc-last-message nil)))) 207 208;; Decide whether now is a good time to display a message. 209(defun eldoc-display-message-p () 210 (and (eldoc-display-message-no-interference-p) 211 ;; If this-command is non-nil while running via an idle 212 ;; timer, we're still in the middle of executing a command, 213 ;; e.g. a query-replace where it would be annoying to 214 ;; overwrite the echo area. 215 (and (not this-command) 216 (symbolp last-command) 217 (intern-soft (symbol-name last-command) 218 eldoc-message-commands)))) 219 220;; Check various conditions about the current environment that might make 221;; it undesirable to print eldoc messages right this instant. 222(defun eldoc-display-message-no-interference-p () 223 (and eldoc-mode 224 (not executing-kbd-macro) 225 (not (and (boundp 'edebug-active) edebug-active)) 226 ;; Having this mode operate in an active minibuffer/echo area causes 227 ;; interference with what's going on there. 228 (not cursor-in-echo-area) 229 (not (eq (selected-window) (minibuffer-window))))) 230 231 232;;;###autoload 233(defvar eldoc-documentation-function nil 234 "If non-nil, function to call to return doc string. 235The function of no args should return a one-line string for displaying 236doc about a function etc. appropriate to the context around point. 237It should return nil if there's no doc appropriate for the context. 238Typically doc is returned if point is on a function-like name or in its 239arg list. 240 241This variable is expected to be made buffer-local by modes (other than 242Emacs Lisp mode) that support Eldoc.") 243 244(defun eldoc-print-current-symbol-info () 245 (condition-case err 246 (and (eldoc-display-message-p) 247 (if eldoc-documentation-function 248 (eldoc-message (funcall eldoc-documentation-function)) 249 (let* ((current-symbol (eldoc-current-symbol)) 250 (current-fnsym (eldoc-fnsym-in-current-sexp)) 251 (doc (cond 252 ((eq current-symbol current-fnsym) 253 (or (eldoc-get-fnsym-args-string current-fnsym) 254 (eldoc-get-var-docstring current-symbol))) 255 (t 256 (or (eldoc-get-var-docstring current-symbol) 257 (eldoc-get-fnsym-args-string current-fnsym)))))) 258 (eldoc-message doc)))) 259 ;; This is run from post-command-hook or some idle timer thing, 260 ;; so we need to be careful that errors aren't ignored. 261 (error (message "eldoc error: %s" err)))) 262 263;; Return a string containing the function parameter list, or 1-line 264;; docstring if function is a subr and no arglist is obtainable from the 265;; docstring or elsewhere. 266(defun eldoc-get-fnsym-args-string (sym) 267 (let ((args nil) 268 (doc nil)) 269 (cond ((not (and sym (symbolp sym) (fboundp sym)))) 270 ((and (eq sym (aref eldoc-last-data 0)) 271 (eq 'function (aref eldoc-last-data 2))) 272 (setq doc (aref eldoc-last-data 1))) 273 ((setq doc (help-split-fundoc (documentation sym t) sym)) 274 (setq args (car doc)) 275 (string-match "\\`[^ )]* ?" args) 276 (setq args (concat "(" (substring args (match-end 0))))) 277 (t 278 (setq args (eldoc-function-argstring sym)))) 279 (cond (args 280 (setq doc (eldoc-docstring-format-sym-doc sym args)) 281 (eldoc-last-data-store sym doc 'function))) 282 doc)) 283 284;; Return a string containing a brief (one-line) documentation string for 285;; the variable. 286(defun eldoc-get-var-docstring (sym) 287 (when sym 288 (cond ((and (eq sym (aref eldoc-last-data 0)) 289 (eq 'variable (aref eldoc-last-data 2))) 290 (aref eldoc-last-data 1)) 291 (t 292 (let ((doc (documentation-property sym 'variable-documentation t))) 293 (cond (doc 294 (setq doc (eldoc-docstring-format-sym-doc 295 sym (eldoc-docstring-first-line doc))) 296 (eldoc-last-data-store sym doc 'variable))) 297 doc))))) 298 299(defun eldoc-last-data-store (symbol doc type) 300 (aset eldoc-last-data 0 symbol) 301 (aset eldoc-last-data 1 doc) 302 (aset eldoc-last-data 2 type)) 303 304;; Note that any leading `*' in the docstring (which indicates the variable 305;; is a user option) is removed. 306(defun eldoc-docstring-first-line (doc) 307 (and (stringp doc) 308 (substitute-command-keys 309 (save-match-data 310 (let ((start (if (string-match "^\\*" doc) (match-end 0) 0))) 311 (cond ((string-match "\n" doc) 312 (substring doc start (match-beginning 0))) 313 ((zerop start) doc) 314 (t (substring doc start)))))))) 315 316;; If the entire line cannot fit in the echo area, the symbol name may be 317;; truncated or eliminated entirely from the output to make room for the 318;; description. 319(defun eldoc-docstring-format-sym-doc (sym doc) 320 (save-match-data 321 (let* ((name (symbol-name sym)) 322 (ea-multi eldoc-echo-area-use-multiline-p) 323 ;; Subtract 1 from window width since emacs will not write 324 ;; any chars to the last column, or in later versions, will 325 ;; cause a wraparound and resize of the echo area. 326 (ea-width (1- (window-width (minibuffer-window)))) 327 (strip (- (+ (length name) (length ": ") (length doc)) ea-width))) 328 (cond ((or (<= strip 0) 329 (eq ea-multi t) 330 (and ea-multi (> (length doc) ea-width))) 331 (format "%s: %s" sym doc)) 332 ((> (length doc) ea-width) 333 (substring (format "%s" doc) 0 ea-width)) 334 ((>= strip (length name)) 335 (format "%s" doc)) 336 (t 337 ;; Show the end of the partial symbol name, rather 338 ;; than the beginning, since the former is more likely 339 ;; to be unique given package namespace conventions. 340 (setq name (substring name strip)) 341 (format "%s: %s" name doc)))))) 342 343 344(defun eldoc-fnsym-in-current-sexp () 345 (let ((p (point))) 346 (eldoc-beginning-of-sexp) 347 (prog1 348 ;; Don't do anything if current word is inside a string. 349 (if (= (or (char-after (1- (point))) 0) ?\") 350 nil 351 (eldoc-current-symbol)) 352 (goto-char p)))) 353 354(defun eldoc-beginning-of-sexp () 355 (let ((parse-sexp-ignore-comments t)) 356 (condition-case err 357 (while (progn 358 (forward-sexp -1) 359 (or (= (char-before) ?\") 360 (> (point) (point-min))))) 361 (error nil)))) 362 363;; returns nil unless current word is an interned symbol. 364(defun eldoc-current-symbol () 365 (let ((c (char-after (point)))) 366 (and c 367 (memq (char-syntax c) '(?w ?_)) 368 (intern-soft (current-word))))) 369 370;; Do indirect function resolution if possible. 371(defun eldoc-symbol-function (fsym) 372 (let ((defn (and (fboundp fsym) 373 (symbol-function fsym)))) 374 (and (symbolp defn) 375 (condition-case err 376 (setq defn (indirect-function fsym)) 377 (error (setq defn nil)))) 378 defn)) 379 380(defun eldoc-function-argstring (fn) 381 (eldoc-function-argstring-format (help-function-arglist fn))) 382 383(defun eldoc-function-argstring-format (arglist) 384 (cond ((not (listp arglist)) 385 (setq arglist nil)) 386 ((symbolp (car arglist)) 387 (setq arglist 388 (mapcar (function (lambda (s) 389 (if (memq s '(&optional &rest)) 390 (symbol-name s) 391 (funcall eldoc-argument-case 392 (symbol-name s))))) 393 arglist))) 394 ((stringp (car arglist)) 395 (setq arglist 396 (mapcar (function (lambda (s) 397 (if (member s '("&optional" "&rest")) 398 s 399 (funcall eldoc-argument-case s)))) 400 arglist)))) 401 (concat "(" (mapconcat 'identity arglist " ") ")")) 402 403 404;; When point is in a sexp, the function args are not reprinted in the echo 405;; area after every possible interactive command because some of them print 406;; their own messages in the echo area; the eldoc functions would instantly 407;; overwrite them unless it is more restrained. 408;; These functions do display-command table management. 409 410(defun eldoc-add-command (&rest cmds) 411 (dolist (name cmds) 412 (and (symbolp name) 413 (setq name (symbol-name name))) 414 (set (intern name eldoc-message-commands) t))) 415 416(defun eldoc-add-command-completions (&rest names) 417 (dolist (name names) 418 (apply 'eldoc-add-command (all-completions name obarray 'commandp)))) 419 420(defun eldoc-remove-command (&rest cmds) 421 (dolist (name cmds) 422 (and (symbolp name) 423 (setq name (symbol-name name))) 424 (unintern name eldoc-message-commands))) 425 426(defun eldoc-remove-command-completions (&rest names) 427 (dolist (name names) 428 (apply 'eldoc-remove-command 429 (all-completions name eldoc-message-commands)))) 430 431 432;; Prime the command list. 433(eldoc-add-command-completions 434 "backward-" "beginning-of-" "move-beginning-of-" "delete-other-windows" 435 "delete-window" "handle-select-window" 436 "end-of-" "move-end-of-" "exchange-point-and-mark" "forward-" 437 "indent-for-tab-command" "goto-" "mark-page" "mark-paragraph" 438 "mouse-set-point" "move-" "pop-global-mark" "next-" "other-window" 439 "previous-" "recenter" "scroll-" "self-insert-command" 440 "split-window-" "up-list" "down-list") 441 442(provide 'eldoc) 443 444;; arch-tag: c9a58f9d-2055-46c1-9b82-7248b71a8375 445;;; eldoc.el ends here 446