1 ;;; eldoc.el --- show function arglist or variable docstring in echo area
3 ;; Copyright (C) 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004,
4 ;; 2005, 2006, 2007, 2008 Free Software Foundation, Inc.
6 ;; Author: Noah Friedman <friedman@splode.com>
7 ;; Maintainer: friedman@splode.com
8 ;; Keywords: extensions
11 ;; This file is part of GNU Emacs.
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 3, or (at your option)
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.
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.
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.
39 ;; One useful way to enable this minor mode is to put the following in your
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)
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'.
52 (require 'help-fns
) ;For fundoc-usage handling functions.
55 "Show function arglist or variable docstring in echo area."
59 (defcustom eldoc-idle-delay
0.50
60 "*Number of seconds of idle time to wait before printing.
61 If user input arrives before this interval of time has elapsed after the
62 last input, no documentation will be printed.
64 If this variable is set to 0, no idle time is required."
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
))
74 (defcustom eldoc-argument-case
'upcase
75 "Case to display argument names of functions, as a symbol.
76 This has two preferred values: `upcase' or `downcase'.
77 Actually, any name of a function which takes a string as an argument and
78 returns another string is acceptable."
79 :type
'(radio (function-item upcase
)
80 (function-item downcase
)
84 (defcustom eldoc-echo-area-use-multiline-p
'truncate-sym-name-if-fit
85 "*Allow long eldoc messages to resize echo area display.
86 If value is t, never attempt to truncate messages; complete symbol name
87 and function arglist or 1-line variable documentation will be displayed
88 even if echo area must be resized to fit.
90 If value is any non-nil value other than t, symbol name may be truncated
91 if it will enable the function arglist or documentation string to fit on a
92 single line without resizing window. Otherwise, behavior is just like
95 If value is nil, messages are always truncated to fit in a single line of
96 display in the echo area. Function or variable symbol name may be
97 truncated 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
))
104 ;;; No user options below here.
106 (defvar eldoc-message-commands-table-size
31
107 "This is used by `eldoc-add-command' to initialize `eldoc-message-commands'
109 It should probably never be necessary to do so, but if you
110 choose to increase the number of buckets, you must do so before loading
111 this file since the obarray is initialized at load time.
112 Remember to keep it a prime number to improve hash performance.")
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.
117 Eldoc does not try to print function arglists, etc. after just any command,
118 because some commands print their own messages in the echo area and these
119 functions would instantly overwrite them. But `self-insert-command' as well
120 as most motion commands are good candidates.
121 This variable contains an obarray of symbols; do not manipulate it
122 directly. Instead, use `eldoc-add-command' and `eldoc-remove-command'.")
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
)
132 (defvar eldoc-timer nil
"eldoc's timer object.")
134 (defvar eldoc-current-idle-delay eldoc-idle-delay
135 "Idle time delay currently in use by timer.
136 This is used to determine if `eldoc-idle-delay' is changed by the user.")
140 (define-minor-mode eldoc-mode
141 "Toggle ElDoc mode on or off.
142 In ElDoc mode, the echo area displays information about a
143 function or variable in the text where point is. If point is
144 on a documented variable, it displays the first line of that
145 variable's doc string. Otherwise it displays the argument list
146 of the function called in the expression point is on.
148 With 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
)
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
)))
159 (defun turn-on-eldoc-mode ()
160 "Unequivocally turn on ElDoc mode (see command `eldoc-mode')."
165 (defun eldoc-schedule-timer ()
167 (memq eldoc-timer timer-idle-list
))
169 (run-with-idle-timer eldoc-idle-delay t
170 'eldoc-print-current-symbol-info
)))
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
))))
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
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
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
)))))
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
))))
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
))))
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 ()
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)))))
233 (defvar eldoc-documentation-function nil
234 "If non-nil, function to call to return doc string.
235 The function of no args should return a one-line string for displaying
236 doc about a function etc. appropriate to the context around point.
237 It should return nil if there's no doc appropriate for the context.
238 Typically doc is returned if point is on a function-like name or in its
241 This variable is expected to be made buffer-local by modes (other than
242 Emacs Lisp mode) that support Eldoc.")
244 (defun eldoc-print-current-symbol-info ()
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))
252 ((eq current-symbol current-fnsym
)
253 (or (eldoc-get-fnsym-args-string current-fnsym
)
254 (eldoc-get-var-docstring current-symbol
)))
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
))))
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)
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)))))
278 (setq args
(eldoc-function-argstring sym
))))
280 (setq doc
(eldoc-docstring-format-sym-doc sym args
))
281 (eldoc-last-data-store sym doc
'function
)))
284 ;; Return a string containing a brief (one-line) documentation string for
286 (defun eldoc-get-var-docstring (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))
292 (let ((doc (documentation-property sym
'variable-documentation t
)))
294 (setq doc
(eldoc-docstring-format-sym-doc
295 sym
(eldoc-docstring-first-line doc
)))
296 (eldoc-last-data-store sym doc
'variable
)))
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
))
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)
308 (substitute-command-keys
310 (let ((start (if (string-match "^\\*" doc
) (match-end 0) 0)))
311 (cond ((string-match "\n" doc
)
312 (substring doc start
(match-beginning 0)))
314 (t (substring doc start
))))))))
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
319 (defun eldoc-docstring-format-sym-doc (sym doc
)
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)
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
))
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
))))))
344 (defun eldoc-fnsym-in-current-sexp ()
346 (eldoc-beginning-of-sexp)
348 ;; Don't do anything if current word is inside a string.
349 (if (= (or (char-after (1- (point))) 0) ?
\")
351 (eldoc-current-symbol))
354 (defun eldoc-beginning-of-sexp ()
355 (let ((parse-sexp-ignore-comments t
))
359 (or (= (char-before) ?
\")
360 (> (point) (point-min)))))
363 ;; returns nil unless current word is an interned symbol.
364 (defun eldoc-current-symbol ()
365 (let ((c (char-after (point))))
367 (memq (char-syntax c
) '(?w ?_
))
368 (intern-soft (current-word)))))
370 ;; Do indirect function resolution if possible.
371 (defun eldoc-symbol-function (fsym)
372 (let ((defn (and (fboundp fsym
)
373 (symbol-function fsym
))))
376 (setq defn
(indirect-function fsym
))
377 (error (setq defn nil
))))
380 (defun eldoc-function-argstring (fn)
381 (eldoc-function-argstring-format (help-function-arglist fn
)))
383 (defun eldoc-function-argstring-format (arglist)
384 (cond ((not (listp arglist
))
386 ((symbolp (car arglist
))
388 (mapcar (function (lambda (s)
389 (if (memq s
'(&optional
&rest
))
391 (funcall eldoc-argument-case
394 ((stringp (car arglist
))
396 (mapcar (function (lambda (s)
397 (if (member s
'("&optional" "&rest"))
399 (funcall eldoc-argument-case s
))))
401 (concat "(" (mapconcat 'identity arglist
" ") ")"))
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.
410 (defun eldoc-add-command (&rest cmds
)
413 (setq name
(symbol-name name
)))
414 (set (intern name eldoc-message-commands
) t
)))
416 (defun eldoc-add-command-completions (&rest names
)
418 (apply 'eldoc-add-command
(all-completions name obarray
'commandp
))))
420 (defun eldoc-remove-command (&rest cmds
)
423 (setq name
(symbol-name name
)))
424 (unintern name eldoc-message-commands
)))
426 (defun eldoc-remove-command-completions (&rest names
)
428 (apply 'eldoc-remove-command
429 (all-completions name eldoc-message-commands
))))
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")
444 ;; arch-tag: c9a58f9d-2055-46c1-9b82-7248b71a8375
445 ;;; eldoc.el ends here