eldoc.el 15.8 KB
Newer Older
1
;;; eldoc.el --- Show function arglist or variable docstring in echo area  -*- lexical-binding:t; -*-
Noah Friedman's avatar
Noah Friedman committed
2

Paul Eggert's avatar
Paul Eggert committed
3
;; Copyright (C) 1996-2015 Free Software Foundation, Inc.
Noah Friedman's avatar
Noah Friedman committed
4

5 6
;; Author: Noah Friedman <friedman@splode.com>
;; Maintainer: friedman@splode.com
Noah Friedman's avatar
Noah Friedman committed
7 8 9
;; Keywords: extensions
;; Created: 1995-10-06

10
;; This file is part of GNU Emacs.
Noah Friedman's avatar
Noah Friedman committed
11

12
;; GNU Emacs is free software: you can redistribute it and/or modify
Noah Friedman's avatar
Noah Friedman committed
13
;; it under the terms of the GNU General Public License as published by
14 15
;; the Free Software Foundation, either version 3 of the License, or
;; (at your option) any later version.
16 17

;; GNU Emacs is distributed in the hope that it will be useful,
Noah Friedman's avatar
Noah Friedman committed
18 19 20
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;; GNU General Public License for more details.
21

Noah Friedman's avatar
Noah Friedman committed
22
;; You should have received a copy of the GNU General Public License
23
;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
Noah Friedman's avatar
Noah Friedman committed
24 25 26

;;; Commentary:

27 28 29 30 31 32 33 34
;; This program was inspired by the behavior of the "mouse documentation
;; window" on many Lisp Machine systems; as you type a function's symbol
;; name as part of a sexp, it will print the argument list for that
;; function.  Behavior is not identical; for example, you need not actually
;; type the function name, you need only move point around in a sexp that
;; calls it.  Also, if point is over a documented variable, it will print
;; the one-line documentation for that variable instead, to remind you of
;; that variable's meaning.
Noah Friedman's avatar
Noah Friedman committed
35 36 37 38

;; One useful way to enable this minor mode is to put the following in your
;; .emacs:
;;
39 40 41
;;      (add-hook 'emacs-lisp-mode-hook 'eldoc-mode)
;;      (add-hook 'lisp-interaction-mode-hook 'eldoc-mode)
;;      (add-hook 'ielm-mode-hook 'eldoc-mode)
Glenn Morris's avatar
Glenn Morris committed
42
;;      (add-hook 'eval-expression-minibuffer-setup-hook 'eldoc-mode)
Noah Friedman's avatar
Noah Friedman committed
43

44
;; Major modes for other languages may use ElDoc by defining an
45
;; appropriate function as the buffer-local value of
Richard M. Stallman's avatar
Richard M. Stallman committed
46
;; `eldoc-documentation-function'.
47

Noah Friedman's avatar
Noah Friedman committed
48 49
;;; Code:

50 51
(defgroup eldoc nil
  "Show function arglist or variable docstring in echo area."
52
  :group 'lisp
53 54 55
  :group 'extensions)

(defcustom eldoc-idle-delay 0.50
56
  "Number of seconds of idle time to wait before printing.
Noah Friedman's avatar
Noah Friedman committed
57 58 59
If user input arrives before this interval of time has elapsed after the
last input, no documentation will be printed.

60 61 62
If this variable is set to 0, no idle time is required."
  :type 'number
  :group 'eldoc)
Noah Friedman's avatar
Noah Friedman committed
63

64 65 66 67 68 69
(defcustom eldoc-print-after-edit nil
  "If non-nil eldoc info is only shown when editing.
Changing the value requires toggling `eldoc-mode'."
  :type 'boolean
  :group 'eldoc)

70
;;;###autoload
71
(defcustom eldoc-minor-mode-string (purecopy " ElDoc")
72
  "String to display in mode line when ElDoc Mode is enabled; nil for none."
73
  :type '(choice string (const :tag "None" nil))
74
  :group 'eldoc)
75

76
(defcustom eldoc-argument-case #'identity
Noah Friedman's avatar
Noah Friedman committed
77 78 79
  "Case to display argument names of functions, as a symbol.
This has two preferred values: `upcase' or `downcase'.
Actually, any name of a function which takes a string as an argument and
80 81
returns another string is acceptable.

82 83
Note that this variable has no effect, unless
`eldoc-documentation-function' handles it explicitly."
84 85 86
  :type '(radio (function-item upcase)
		(function-item downcase)
                function)
87
  :group 'eldoc)
Stefan Monnier's avatar
Stefan Monnier committed
88
(make-obsolete-variable 'eldoc-argument-case nil "25.1")
Noah Friedman's avatar
Noah Friedman committed
89

90
(defcustom eldoc-echo-area-use-multiline-p 'truncate-sym-name-if-fit
91
  "Allow long ElDoc messages to resize echo area display.
92
If value is t, never attempt to truncate messages; complete symbol name
93 94 95
and function arglist or 1-line variable documentation will be displayed
even if echo area must be resized to fit.

96
If value is any non-nil value other than t, symbol name may be truncated
97 98 99 100 101 102
if it will enable the function arglist or documentation string to fit on a
single line without resizing window.  Otherwise, behavior is just like
former case.

If value is nil, messages are always truncated to fit in a single line of
display in the echo area.  Function or variable symbol name may be
103 104
truncated to make more of the arglist or documentation string visible.

105 106
Note that this variable has no effect, unless
`eldoc-documentation-function' handles it explicitly."
107 108 109 110 111 112
  :type '(radio (const :tag "Always" t)
                (const :tag "Never" nil)
                (const :tag "Yes, but truncate symbol names if it will\
 enable argument list to fit on one line" truncate-sym-name-if-fit))
  :group 'eldoc)

113 114
(defface eldoc-highlight-function-argument
  '((t (:inherit bold)))
115
  "Face used for the argument at point in a function's argument list.
116 117
Note that this face has no effect unless the `eldoc-documentation-function'
handles it explicitly."
118 119
  :group 'eldoc)

120 121
;;; No user options below here.

122
(defvar eldoc-message-commands-table-size 31
123
  "Used by `eldoc-add-command' to initialize `eldoc-message-commands' obarray.
124 125 126 127 128
It should probably never be necessary to do so, but if you
choose to increase the number of buckets, you must do so before loading
this file since the obarray is initialized at load time.
Remember to keep it a prime number to improve hash performance.")

129 130
(defvar eldoc-message-commands
  ;; Don't define as `defconst' since it would then go to (read-only) purespace.
131 132
  (make-vector eldoc-message-commands-table-size 0)
  "Commands after which it is appropriate to print in the echo area.
133
ElDoc does not try to print function arglists, etc., after just any command,
134
because some commands print their own messages in the echo area and these
135
functions would instantly overwrite them.  But `self-insert-command' as well
136 137 138 139
as most motion commands are good candidates.
This variable contains an obarray of symbols; do not manipulate it
directly.  Instead, use `eldoc-add-command' and `eldoc-remove-command'.")

140
;; Not a constant.
141 142
(defvar eldoc-last-data (make-vector 3 nil)
  ;; Don't define as `defconst' since it would then go to (read-only) purespace.
143 144
  "Bookkeeping; elements are as follows:
  0 - contains the last symbol read from the buffer.
145 146
  1 - contains the string last displayed in the echo area for variables,
      or argument string for functions.
147 148
  2 - `function' if function args, `variable' if variable documentation.")
(make-obsolete-variable 'eldoc-last-data "use your own instead" "25.1")
149

150
(defvar eldoc-last-message nil)
Noah Friedman's avatar
Noah Friedman committed
151

152
(defvar eldoc-timer nil "ElDoc's timer object.")
153

154
(defvar eldoc-current-idle-delay eldoc-idle-delay
155
  "Idle time delay currently in use by timer.
156
This is used to determine if `eldoc-idle-delay' is changed by the user.")
Noah Friedman's avatar
Noah Friedman committed
157

158
(defvar eldoc-message-function #'eldoc-minibuffer-message
159 160 161
  "The function used by `eldoc-message' to display messages.
It should receive the same arguments as `message'.")

162 163 164 165 166 167 168 169 170 171
(defun eldoc-edit-message-commands ()
  (let ((cmds (make-vector 31 0))
	(re (regexp-opt '("delete" "insert" "edit" "electric" "newline"))))
    (mapatoms (lambda (s)
		(and (commandp s)
		     (string-match-p re (symbol-name s))
		     (intern (symbol-name s) cmds)))
	      obarray)
    cmds))

Noah Friedman's avatar
Noah Friedman committed
172 173

;;;###autoload
174
(define-minor-mode eldoc-mode
Chong Yidong's avatar
Chong Yidong committed
175 176 177 178 179 180 181 182 183 184 185
  "Toggle echo area display of Lisp objects at point (ElDoc mode).
With a prefix argument ARG, enable ElDoc mode if ARG is positive,
and disable it otherwise.  If called from Lisp, enable ElDoc mode
if ARG is omitted or nil.

ElDoc mode is a buffer-local minor mode.  When enabled, the echo
area displays information about a function or variable in the
text where point is.  If point is on a documented variable, it
displays the first line of that variable's doc string.  Otherwise
it displays the argument list of the function called in the
expression point is on."
Lute Kamstra's avatar
Lute Kamstra committed
186
  :group 'eldoc :lighter eldoc-minor-mode-string
187
  (setq eldoc-last-message nil)
188
  (cond
189
   ((memq eldoc-documentation-function '(nil ignore))
190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205
    (message "There is no ElDoc support in this buffer")
    (setq eldoc-mode nil))
   (eldoc-mode
    (when eldoc-print-after-edit
      (setq-local eldoc-message-commands (eldoc-edit-message-commands)))
    (add-hook 'post-command-hook 'eldoc-schedule-timer nil t)
    (add-hook 'pre-command-hook 'eldoc-pre-command-refresh-echo-area nil t))
   (t
    (kill-local-variable 'eldoc-message-commands)
    (remove-hook 'post-command-hook 'eldoc-schedule-timer t)
    (remove-hook 'pre-command-hook 'eldoc-pre-command-refresh-echo-area t))))

;;;###autoload
(define-minor-mode global-eldoc-mode
  "Enable `eldoc-mode' in all buffers where it's applicable."
  :group 'eldoc :global t
206 207
  :initialize 'custom-initialize-delay
  :init-value t
208 209
  (setq eldoc-last-message nil)
  (if global-eldoc-mode
210
      (progn
211 212 213 214
	(add-hook 'post-command-hook #'eldoc-schedule-timer)
	(add-hook 'pre-command-hook #'eldoc-pre-command-refresh-echo-area))
    (remove-hook 'post-command-hook #'eldoc-schedule-timer)
    (remove-hook 'pre-command-hook #'eldoc-pre-command-refresh-echo-area)))
215

Noah Friedman's avatar
Noah Friedman committed
216
;;;###autoload
217
(define-obsolete-function-alias 'turn-on-eldoc-mode 'eldoc-mode "24.4")
Noah Friedman's avatar
Noah Friedman committed
218

219

220 221
(defun eldoc-schedule-timer ()
  (or (and eldoc-timer
222
           (memq eldoc-timer timer-idle-list)) ;FIXME: Why?
223
      (setq eldoc-timer
224 225
            (run-with-idle-timer
	     eldoc-idle-delay t
226 227
	     (lambda ()
               (when (or eldoc-mode
228 229 230
                         (and global-eldoc-mode
                              (not (memq eldoc-documentation-function
                                         '(nil ignore)))))
231
                 (eldoc-print-current-symbol-info))))))
232 233 234 235 236 237

  ;; If user has changed the idle delay, update the timer.
  (cond ((not (= eldoc-idle-delay eldoc-current-idle-delay))
         (setq eldoc-current-idle-delay eldoc-idle-delay)
         (timer-set-idle-time eldoc-timer eldoc-idle-delay t))))

238 239 240 241 242 243 244 245
(defvar eldoc-mode-line-string nil)
(put 'eldoc-mode-line-string 'risky-local-variable t)

(defun eldoc-minibuffer-message (format-string &rest args)
  "Display messages in the mode-line when in the minibuffer.
Otherwise work like `message'."
  (if (minibufferp)
      (progn
246
	(add-hook 'minibuffer-exit-hook
247 248 249
		  (lambda () (setq eldoc-mode-line-string nil
			      ;; http://debbugs.gnu.org/16920
			      eldoc-last-message nil))
250
		  nil t)
251 252 253 254 255 256 257 258 259 260
	(with-current-buffer
	    (window-buffer
	     (or (window-in-direction 'above (minibuffer-window))
		 (minibuffer-selected-window)
		 (get-largest-window)))
	  (unless (and (listp mode-line-format)
		       (assq 'eldoc-mode-line-string mode-line-format))
	    (setq mode-line-format
		  (list "" '(eldoc-mode-line-string
			     (" " eldoc-mode-line-string " "))
261 262 263 264 265
			mode-line-format)))
          (setq eldoc-mode-line-string
                (when (stringp format-string)
                  (apply 'format format-string args)))
          (force-mode-line-update)))
266 267
    (apply 'message format-string args)))

268 269
(defun eldoc-message (&rest args)
  (let ((omessage eldoc-last-message))
270
    (setq eldoc-last-message
271 272 273 274 275 276 277
	  (cond ((eq (car args) eldoc-last-message) eldoc-last-message)
		((null (car args)) nil)
		;; If only one arg, no formatting to do, so put it in
		;; eldoc-last-message so eq test above might succeed on
		;; subsequent calls.
		((null (cdr args)) (car args))
		(t (apply 'format args))))
278 279 280
    ;; In emacs 19.29 and later, and XEmacs 19.13 and later, all messages
    ;; are recorded in a log.  Do not put eldoc messages in that log since
    ;; they are Legion.
281 282
    ;; Emacs way of preventing log messages.
    (let ((message-log-max nil))
283 284 285
      (cond (eldoc-last-message
	     (funcall eldoc-message-function "%s" eldoc-last-message))
	    (omessage (funcall eldoc-message-function nil)))))
286 287
  eldoc-last-message)

288 289 290 291
(defun eldoc--message-command-p (command)
  (and (symbolp command)
       (intern-soft (symbol-name command) eldoc-message-commands)))

292 293 294 295 296 297 298 299
;; This function goes on pre-command-hook for XEmacs or when using idle
;; timers in Emacs.  Motion commands clear the echo area for some reason,
;; which make eldoc messages flicker or disappear just before motion
;; begins.  This function reprints the last eldoc message immediately
;; before the next command executes, which does away with the flicker.
;; This doesn't seem to be required for Emacs 19.28 and earlier.
(defun eldoc-pre-command-refresh-echo-area ()
  (and eldoc-last-message
300
       (not (minibufferp))      ;We don't use the echo area when in minibuffer.
301
       (if (and (eldoc-display-message-no-interference-p)
302
		(eldoc--message-command-p this-command))
303
	   (eldoc-message eldoc-last-message)
304 305
         ;; No need to call eldoc-message since the echo area will be cleared
         ;; for us, but do note that the last-message will be gone.
306
         (setq eldoc-last-message nil))))
307 308 309

;; Decide whether now is a good time to display a message.
(defun eldoc-display-message-p ()
310
  (and (eldoc-display-message-no-interference-p)
311 312 313 314
       ;; If this-command is non-nil while running via an idle
       ;; timer, we're still in the middle of executing a command,
       ;; e.g. a query-replace where it would be annoying to
       ;; overwrite the echo area.
315 316 317
       (not this-command)
       (eldoc--message-command-p last-command)))

Noah Friedman's avatar
Noah Friedman committed
318

319 320
;; Check various conditions about the current environment that might make
;; it undesirable to print eldoc messages right this instant.
321
(defun eldoc-display-message-no-interference-p ()
322
  (not (or executing-kbd-macro (bound-and-true-p edebug-active))))
323

324

325
;;;###autoload
326
(defvar eldoc-documentation-function #'ignore
327
  "Function to call to return doc string.
328 329 330 331 332 333
The function of no args should return a one-line string for displaying
doc about a function etc. appropriate to the context around point.
It should return nil if there's no doc appropriate for the context.
Typically doc is returned if point is on a function-like name or in its
arg list.

334 335 336 337 338
The result is used as is, so the function must explicitly handle
the variables `eldoc-argument-case' and `eldoc-echo-area-use-multiline-p',
and the face `eldoc-highlight-function-argument', if they are to have any
effect.

339 340 341 342 343 344
Major modes should modify this variable using `add-function', for example:
  (add-function :before-until (local 'eldoc-documentation-function)
                #'foo-mode-eldoc-function)
so that the global documentation function (i.e. the default value of the
variable) is taken into account if the major mode specific function does not
return any documentation.")
345

346
(defun eldoc-print-current-symbol-info ()
347 348 349
  ;; This is run from post-command-hook or some idle timer thing,
  ;; so we need to be careful that errors aren't ignored.
  (with-demoted-errors "eldoc error: %s"
350 351 352 353 354
    (and (or (eldoc-display-message-p)
             ;; Erase the last message if we won't display a new one.
             (when eldoc-last-message
               (eldoc-message nil)
               nil))
355 356
	 (eldoc-message (funcall eldoc-documentation-function)))))

Noah Friedman's avatar
Noah Friedman committed
357

358 359 360 361 362 363 364
;; When point is in a sexp, the function args are not reprinted in the echo
;; area after every possible interactive command because some of them print
;; their own messages in the echo area; the eldoc functions would instantly
;; overwrite them unless it is more restrained.
;; These functions do display-command table management.

(defun eldoc-add-command (&rest cmds)
365 366 367 368
  (dolist (name cmds)
    (and (symbolp name)
         (setq name (symbol-name name)))
    (set (intern name eldoc-message-commands) t)))
369 370

(defun eldoc-add-command-completions (&rest names)
371
  (dolist (name names)
372
    (apply #'eldoc-add-command (all-completions name obarray 'commandp))))
373 374

(defun eldoc-remove-command (&rest cmds)
375 376 377 378
  (dolist (name cmds)
    (and (symbolp name)
         (setq name (symbol-name name)))
    (unintern name eldoc-message-commands)))
379 380

(defun eldoc-remove-command-completions (&rest names)
381
  (dolist (name names)
382
    (apply #'eldoc-remove-command
383
           (all-completions name eldoc-message-commands))))
384

385

386 387
;; Prime the command list.
(eldoc-add-command-completions
388 389 390 391 392 393 394
 "backward-" "beginning-of-" "delete-other-windows" "delete-window"
 "down-list" "end-of-" "exchange-point-and-mark" "forward-" "goto-"
 "handle-select-window" "indent-for-tab-command" "left-" "mark-page"
 "mark-paragraph" "mouse-set-point" "move-" "move-beginning-of-"
 "move-end-of-" "next-" "other-window" "pop-global-mark" "previous-"
 "recenter" "right-" "scroll-" "self-insert-command" "split-window-"
 "up-list")
Noah Friedman's avatar
Noah Friedman committed
395 396 397 398

(provide 'eldoc)

;;; eldoc.el ends here