eldoc.el 17.6 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) 1996-2016 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
    (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)
200 201 202 203
    (remove-hook 'pre-command-hook 'eldoc-pre-command-refresh-echo-area t)
    (when eldoc-timer
      (cancel-timer eldoc-timer)
      (setq eldoc-timer nil)))))
204 205 206

;;;###autoload
(define-minor-mode global-eldoc-mode
Lars Ingebrigtsen's avatar
Lars Ingebrigtsen committed
207 208 209 210 211 212 213 214 215 216
  "Toggle Global Eldoc mode on or off.
With a prefix argument ARG, enable Global Eldoc mode if ARG is
positive, and disable it otherwise.  If called from Lisp, enable
the mode if ARG is omitted or nil, and toggle it if ARG is toggle.

If Global Eldoc mode is on, `eldoc-mode' will be enabled in all
buffers where it's applicable.  These are buffers that have modes
that have enabled eldoc support.  See `eldoc-documentation-function'."
  :group 'eldoc
  :global t
217 218
  :initialize 'custom-initialize-delay
  :init-value t
219 220
  (setq eldoc-last-message nil)
  (if global-eldoc-mode
221
      (progn
222 223 224 225
	(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)))
226

Noah Friedman's avatar
Noah Friedman committed
227
;;;###autoload
228
(define-obsolete-function-alias 'turn-on-eldoc-mode 'eldoc-mode "24.4")
Noah Friedman's avatar
Noah Friedman committed
229

230

231 232
(defun eldoc-schedule-timer ()
  (or (and eldoc-timer
233
           (memq eldoc-timer timer-idle-list)) ;FIXME: Why?
234
      (setq eldoc-timer
235
            (run-with-idle-timer
Dmitry Gutov's avatar
Dmitry Gutov committed
236
	     eldoc-idle-delay nil
237 238
	     (lambda ()
               (when (or eldoc-mode
239 240 241
                         (and global-eldoc-mode
                              (not (memq eldoc-documentation-function
                                         '(nil ignore)))))
242
                 (eldoc-print-current-symbol-info))))))
243 244 245 246 247 248

  ;; 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))))

249 250 251 252 253 254 255 256
(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
257
	(add-hook 'minibuffer-exit-hook
258 259 260
		  (lambda () (setq eldoc-mode-line-string nil
			      ;; http://debbugs.gnu.org/16920
			      eldoc-last-message nil))
261
		  nil t)
262 263 264 265 266 267 268 269 270 271
	(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 " "))
272 273 274
			mode-line-format)))
          (setq eldoc-mode-line-string
                (when (stringp format-string)
275
                  (apply #'format-message format-string args)))
276
          (force-mode-line-update)))
277 278
    (apply 'message format-string args)))

279 280
(defun eldoc-message (&rest args)
  (let ((omessage eldoc-last-message))
281
    (setq eldoc-last-message
282 283 284 285 286 287
	  (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))
288
		(t (apply #'format-message args))))
289 290 291
    ;; 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.
292 293
    ;; Emacs way of preventing log messages.
    (let ((message-log-max nil))
294 295 296
      (cond (eldoc-last-message
	     (funcall eldoc-message-function "%s" eldoc-last-message))
	    (omessage (funcall eldoc-message-function nil)))))
297 298
  eldoc-last-message)

299 300 301 302
(defun eldoc--message-command-p (command)
  (and (symbolp command)
       (intern-soft (symbol-name command) eldoc-message-commands)))

303 304 305 306 307 308 309 310
;; 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
311
       (not (minibufferp))      ;We don't use the echo area when in minibuffer.
312
       (if (and (eldoc-display-message-no-interference-p)
313
		(eldoc--message-command-p this-command))
314
	   (eldoc-message eldoc-last-message)
315 316
         ;; 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.
317
         (setq eldoc-last-message nil))))
318 319 320

;; Decide whether now is a good time to display a message.
(defun eldoc-display-message-p ()
321
  (and (eldoc-display-message-no-interference-p)
322 323 324 325
       ;; 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.
326 327 328
       (not this-command)
       (eldoc--message-command-p last-command)))

Noah Friedman's avatar
Noah Friedman committed
329

330 331
;; Check various conditions about the current environment that might make
;; it undesirable to print eldoc messages right this instant.
332
(defun eldoc-display-message-no-interference-p ()
333
  (not (or executing-kbd-macro (bound-and-true-p edebug-active))))
334

335

336
;;;###autoload
337
(defvar eldoc-documentation-function #'ignore
338
  "Function to call to return doc string.
339 340 341 342 343 344
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.

345 346 347 348 349
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.

350
Major modes should modify this variable using `add-function', for example:
Paul Eggert's avatar
Paul Eggert committed
351 352
  (add-function :before-until (local \\='eldoc-documentation-function)
                #\\='foo-mode-eldoc-function)
353 354 355
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.")
356

357
(defun eldoc-print-current-symbol-info ()
358 359 360
  ;; 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"
361 362 363 364 365
    (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))
366 367
	 (eldoc-message (funcall eldoc-documentation-function)))))

368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393
;; If the entire line cannot fit in the echo area, the symbol name may be
;; truncated or eliminated entirely from the output to make room for the
;; description.
(defun eldoc-docstring-format-sym-doc (prefix doc &optional face)
  (when (symbolp prefix)
    (setq prefix (concat (propertize (symbol-name prefix) 'face face) ": ")))
  (let* ((ea-multi eldoc-echo-area-use-multiline-p)
         ;; Subtract 1 from window width since emacs will not write
         ;; any chars to the last column, or in later versions, will
         ;; cause a wraparound and resize of the echo area.
         (ea-width (1- (window-width (minibuffer-window))))
         (strip (- (+ (length prefix) (length doc)) ea-width)))
    (cond ((or (<= strip 0)
               (eq ea-multi t)
               (and ea-multi (> (length doc) ea-width)))
           (concat prefix doc))
          ((> (length doc) ea-width)
           (substring (format "%s" doc) 0 ea-width))
          ((>= strip (string-match-p ":? *\\'" prefix))
           doc)
          (t
           ;; Show the end of the partial symbol name, rather
           ;; than the beginning, since the former is more likely
           ;; to be unique given package namespace conventions.
           (concat (substring prefix strip) doc)))))

394 395 396 397 398 399 400
;; 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)
401 402 403 404
  (dolist (name cmds)
    (and (symbolp name)
         (setq name (symbol-name name)))
    (set (intern name eldoc-message-commands) t)))
405 406

(defun eldoc-add-command-completions (&rest names)
407
  (dolist (name names)
408
    (apply #'eldoc-add-command (all-completions name obarray 'commandp))))
409 410

(defun eldoc-remove-command (&rest cmds)
411 412 413 414
  (dolist (name cmds)
    (and (symbolp name)
         (setq name (symbol-name name)))
    (unintern name eldoc-message-commands)))
415 416

(defun eldoc-remove-command-completions (&rest names)
417
  (dolist (name names)
418
    (apply #'eldoc-remove-command
419
           (all-completions name eldoc-message-commands))))
420

421

422 423
;; Prime the command list.
(eldoc-add-command-completions
424
 "back-to-indentation"
425 426 427 428 429 430 431
 "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
432 433 434 435

(provide 'eldoc)

;;; eldoc.el ends here