emacs / lisp / button.el

  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
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
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
;;; button.el --- clickable buttons
;;
;; Copyright (C) 2001, 2002, 2003, 2004, 2005,
;;   2006, 2007, 2008, 2009 Free Software Foundation, Inc.
;;
;; Author: Miles Bader <miles@gnu.org>
;; Keywords: extensions
;;
;; This file is part of GNU Emacs.
;;
;; GNU Emacs is free software: you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation, either version 3 of the License, or
;; (at your option) any later version.

;; GNU Emacs is distributed in the hope that it will be useful,
;; 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.

;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.

;;; Commentary:
;;
;; This package defines functions for inserting and manipulating
;; clickable buttons in Emacs buffers, such as might be used for help
;; hyperlinks, etc.
;;
;; In some ways it duplicates functionality also offered by the
;; `widget' package, but the button package has the advantage that it
;; is (1) much faster, (2) much smaller, and (3) much, much, simpler
;; (the code, that is, not the interface).
;;
;; Buttons can either use overlays, in which case the button is
;; represented by the overlay itself, or text-properties, in which case
;; the button is represented by a marker or buffer-position pointing
;; somewhere in the button.  In the latter case, no markers into the
;; buffer are retained, which is important for speed if there are are
;; extremely large numbers of buttons.
;;
;; Using `define-button-type' to define default properties for buttons
;; is not necessary, but it is is encouraged, since doing so makes the
;; resulting code clearer and more efficient.
;;

;;; Code:


;; Globals

;; Use color for the MS-DOS port because it doesn't support underline.
;; FIXME if MS-DOS correctly answers the (supports) question, it need
;; no longer be a special case.
(defface button '((((type pc) (class color))
		   (:foreground "lightblue"))
		  (((supports :underline t)) :underline t)
		  (t (:foreground "lightblue")))
  "Default face used for buttons."
  :group 'basic-faces)

(defvar button-map
  (let ((map (make-sparse-keymap)))
    ;; The following definition needs to avoid using escape sequences that
    ;; might get converted to ^M when building loaddefs.el
    (define-key map [(control ?m)] 'push-button)
    (define-key map [mouse-2] 'push-button)
    map)
  "Keymap used by buttons.")

(defvar button-buffer-map
  (let ((map (make-sparse-keymap)))
    (define-key map [?\t] 'forward-button)
    (define-key map "\e\t" 'backward-button)
    (define-key map [backtab] 'backward-button)
    map)
  "Keymap useful for buffers containing buttons.
Mode-specific keymaps may want to use this as their parent keymap.")

;; Default properties for buttons
(put 'default-button 'face 'button)
(put 'default-button 'mouse-face 'highlight)
(put 'default-button 'keymap button-map)
(put 'default-button 'type 'button)
;; action may be either a function to call, or a marker to go to
(put 'default-button 'action 'ignore)
(put 'default-button 'help-echo "mouse-2, RET: Push this button")
;; Make overlay buttons go away if their underlying text is deleted.
(put 'default-button 'evaporate t)
;; Prevent insertions adjacent to the text-property buttons from
;; inheriting its properties.
(put 'default-button 'rear-nonsticky t)

;; A `category-symbol' property for the default button type
(put 'button 'button-category-symbol 'default-button)


;; Button types (which can be used to hold default properties for buttons)

;; Because button-type properties are inherited by buttons using the
;; special `category' property (implemented by both overlays and
;; text-properties), we need to store them on a symbol to which the
;; `category' properties can point.  Instead of using the symbol that's
;; the name of each button-type, however, we use a separate symbol (with
;; `-button' appended, and uninterned) to store the properties.  This is
;; to avoid name clashes.

;; [this is an internal function]
(defsubst button-category-symbol (type)
  "Return the symbol used by button-type TYPE to store properties.
Buttons inherit them by setting their `category' property to that symbol."
  (or (get type 'button-category-symbol)
      (error "Unknown button type `%s'" type)))

(defun define-button-type (name &rest properties)
  "Define a `button type' called NAME (a symbol).
The remaining arguments form a sequence of PROPERTY VALUE pairs,
specifying properties to use as defaults for buttons with this type
\(a button's type may be set by giving it a `type' property when
creating the button, using the :type keyword argument).

In addition, the keyword argument :supertype may be used to specify a
button-type from which NAME inherits its default property values
\(however, the inheritance happens only when NAME is defined; subsequent
changes to a supertype are not reflected in its subtypes)."
  (let ((catsym (make-symbol (concat (symbol-name name) "-button")))
	(super-catsym
	 (button-category-symbol
	  (or (plist-get properties 'supertype)
	      (plist-get properties :supertype)
	      'button))))
    ;; Provide a link so that it's easy to find the real symbol.
    (put name 'button-category-symbol catsym)
    ;; Initialize NAME's properties using the global defaults.
    (let ((default-props (symbol-plist super-catsym)))
      (while default-props
	(put catsym (pop default-props) (pop default-props))))
    ;; Add NAME as the `type' property, which will then be returned as
    ;; the type property of individual buttons.
    (put catsym 'type name)
    ;; Add the properties in PROPERTIES to the real symbol.
    (while properties
      (let ((prop (pop properties)))
	(when (eq prop :supertype)
	  (setq prop 'supertype))
	(put catsym prop (pop properties))))
    ;; Make sure there's a `supertype' property
    (unless (get catsym 'supertype)
      (put catsym 'supertype 'button))
    name))

(defun button-type-put (type prop val)
  "Set the button-type TYPE's PROP property to VAL."
  (put (button-category-symbol type) prop val))

(defun button-type-get (type prop)
  "Get the property of button-type TYPE named PROP."
  (get (button-category-symbol type) prop))

(defun button-type-subtype-p (type supertype)
  "Return t if button-type TYPE is a subtype of SUPERTYPE."
  (or (eq type supertype)
      (and type
	   (button-type-subtype-p (button-type-get type 'supertype)
				  supertype))))


;; Button properties and other attributes

(defun button-start (button)
  "Return the position at which BUTTON starts."
  (if (overlayp button)
      (overlay-start button)
    ;; Must be a text-property button.
    (or (previous-single-property-change (1+ button) 'button)
	(point-min))))

(defun button-end (button)
  "Return the position at which BUTTON ends."
  (if (overlayp button)
      (overlay-end button)
    ;; Must be a text-property button.
    (or (next-single-property-change button 'button)
	(point-max))))

(defun button-get (button prop)
  "Get the property of button BUTTON named PROP."
  (if (overlayp button)
      (overlay-get button prop)
    ;; Must be a text-property button.
    (get-text-property button prop)))

(defun button-put (button prop val)
  "Set BUTTON's PROP property to VAL."
  ;; Treat some properties specially.
  (cond ((memq prop '(type :type))
	 ;; We translate a `type' property a `category' property, since
	 ;; that's what's actually used by overlays/text-properties for
	 ;; inheriting properties.
	 (setq prop 'category)
	 (setq val (button-category-symbol val)))
	((eq prop 'category)
	 ;; Disallow updating the `category' property directly.
	 (error "Button `category' property may not be set directly")))
  ;; Add the property.
  (if (overlayp button)
      (overlay-put button prop val)
    ;; Must be a text-property button.
    (put-text-property
     (or (previous-single-property-change (1+ button) 'button)
	 (point-min))
     (or (next-single-property-change button 'button)
	 (point-max))
     prop val)))

(defsubst button-activate (button &optional use-mouse-action)
  "Call BUTTON's action property.
If USE-MOUSE-ACTION is non-nil, invoke the button's mouse-action
instead of its normal action; if the button has no mouse-action,
the normal action is used instead."
  (let ((action (or (and use-mouse-action (button-get button 'mouse-action))
		    (button-get button 'action))))
    (if (markerp action)
	(save-selected-window
	  (select-window (display-buffer (marker-buffer action)))
	  (goto-char action)
	  (recenter 0))
      (funcall action button))))

(defun button-label (button)
  "Return BUTTON's text label."
  (buffer-substring-no-properties (button-start button) (button-end button)))

(defsubst button-type (button)
  "Return BUTTON's button-type."
  (button-get button 'type))

(defun button-has-type-p (button type)
  "Return t if BUTTON has button-type TYPE, or one of TYPE's subtypes."
  (button-type-subtype-p (button-get button 'type) type))


;; Creating overlay buttons

(defun make-button (beg end &rest properties)
  "Make a button from BEG to END in the current buffer.
The remaining arguments form a sequence of PROPERTY VALUE pairs,
specifying properties to add to the button.
In addition, the keyword argument :type may be used to specify a
button-type from which to inherit other properties; see
`define-button-type'.

Also see `make-text-button', `insert-button'."
  (let ((overlay (make-overlay beg end nil t nil)))
    (while properties
      (button-put overlay (pop properties) (pop properties)))
    ;; Put a pointer to the button in the overlay, so it's easy to get
    ;; when we don't actually have a reference to the overlay.
    (overlay-put overlay 'button overlay)
    ;; If the user didn't specify a type, use the default.
    (unless (overlay-get overlay 'category)
      (overlay-put overlay 'category 'default-button))
    ;; OVERLAY is the button, so return it
    overlay))

(defun insert-button (label &rest properties)
  "Insert a button with the label LABEL.
The remaining arguments form a sequence of PROPERTY VALUE pairs,
specifying properties to add to the button.
In addition, the keyword argument :type may be used to specify a
button-type from which to inherit other properties; see
`define-button-type'.

Also see `insert-text-button', `make-button'."
  (apply #'make-button
	 (prog1 (point) (insert label))
	 (point)
	 properties))


;; Creating text-property buttons

(defun make-text-button (beg end &rest properties)
  "Make a button from BEG to END in the current buffer.
The remaining arguments form a sequence of PROPERTY VALUE pairs,
specifying properties to add to the button.
In addition, the keyword argument :type may be used to specify a
button-type from which to inherit other properties; see
`define-button-type'.

This function is like `make-button', except that the button is actually
part of the text instead of being a property of the buffer.  Creating
large numbers of buttons can also be somewhat faster using
`make-text-button'.

BEG can also be a string, in which case it is made into a button.

Also see `insert-text-button'."
  (let ((object nil)
        (type-entry
	 (or (plist-member properties 'type)
	     (plist-member properties :type))))
    (when (stringp beg)
      (setq object beg beg 0 end (length object)))
    ;; Disallow setting the `category' property directly.
    (when (plist-get properties 'category)
      (error "Button `category' property may not be set directly"))
    (if (null type-entry)
	;; The user didn't specify a `type' property, use the default.
	(setq properties (cons 'category (cons 'default-button properties)))
      ;; The user did specify a `type' property.  Translate it into a
      ;; `category' property, which is what's actually used by
      ;; text-properties for inheritance.
      (setcar type-entry 'category)
      (setcar (cdr type-entry)
	      (button-category-symbol (car (cdr type-entry)))))
    ;; Now add all the text properties at once
    (add-text-properties beg end
                         ;; Each button should have a non-eq `button'
                         ;; property so that next-single-property-change can
                         ;; detect boundaries reliably.
                         (cons 'button (cons (list t) properties))
                         object)
    ;; Return something that can be used to get at the button.
    beg))

(defun insert-text-button (label &rest properties)
  "Insert a button with the label LABEL.
The remaining arguments form a sequence of PROPERTY VALUE pairs,
specifying properties to add to the button.
In addition, the keyword argument :type may be used to specify a
button-type from which to inherit other properties; see
`define-button-type'.

This function is like `insert-button', except that the button is
actually part of the text instead of being a property of the buffer.
Creating large numbers of buttons can also be somewhat faster using
`insert-text-button'.

Also see `make-text-button'."
  (apply #'make-text-button
	 (prog1 (point) (insert label))
	 (point)
	 properties))


;; Finding buttons in a buffer

(defun button-at (pos)
  "Return the button at position POS in the current buffer, or nil."
  (let ((button (get-char-property pos 'button)))
    (if (or (overlayp button) (null button))
	button
      ;; Must be a text-property button; return a marker pointing to it.
      (copy-marker pos t))))

(defun next-button (pos &optional count-current)
  "Return the next button after position POS in the current buffer.
If COUNT-CURRENT is non-nil, count any button at POS in the search,
instead of starting at the next button."
    (unless count-current
      ;; Search for the next button boundary.
      (setq pos (next-single-char-property-change pos 'button)))
    (and (< pos (point-max))
	 (or (button-at pos)
	     ;; We must have originally been on a button, and are now in
	     ;; the inter-button space.  Recurse to find a button.
	     (next-button pos))))

(defun previous-button (pos &optional count-current)
  "Return the previous button before position POS in the current buffer.
If COUNT-CURRENT is non-nil, count any button at POS in the search,
instead of starting at the next button."
  (let ((button (button-at pos)))
    (if button
	(if count-current
	    button
	  ;; We started out on a button, so move to its start and look
	  ;; for the previous button boundary.
	  (setq pos (previous-single-char-property-change
		     (button-start button) 'button))
	  (let ((new-button (button-at pos)))
	    (if new-button
		;; We are in a button again; this can happen if there
		;; are adjacent buttons (or at bob).
		(unless (= pos (button-start button)) new-button)
	      ;; We are now in the space between buttons.
	      (previous-button pos))))
      ;; We started out in the space between buttons.
      (setq pos (previous-single-char-property-change pos 'button))
      (or (button-at pos)
	  (and (> pos (point-min))
	       (button-at (1- pos)))))))


;; User commands

(defun push-button (&optional pos use-mouse-action)
  "Perform the action specified by a button at location POS.
POS may be either a buffer position or a mouse-event.  If
USE-MOUSE-ACTION is non-nil, invoke the button's mouse-action
instead of its normal action; if the button has no mouse-action,
the normal action is used instead.  The action may be either a
function to call or a marker to display.
POS defaults to point, except when `push-button' is invoked
interactively as the result of a mouse-event, in which case, the
mouse event is used.
If there's no button at POS, do nothing and return nil, otherwise
return t."
  (interactive
   (list (if (integerp last-command-event) (point) last-command-event)))
  (if (and (not (integerp pos)) (eventp pos))
      ;; POS is a mouse event; switch to the proper window/buffer
      (let ((posn (event-start pos)))
	(with-current-buffer (window-buffer (posn-window posn))
	  (push-button (posn-point posn) t)))
    ;; POS is just normal position
    (let ((button (button-at (or pos (point)))))
      (if (not button)
	  nil
	(button-activate button use-mouse-action)
	t))))

(defun forward-button (n &optional wrap display-message)
  "Move to the Nth next button, or Nth previous button if N is negative.
If N is 0, move to the start of any button at point.
If WRAP is non-nil, moving past either end of the buffer continues from the
other end.
If DISPLAY-MESSAGE is non-nil, the button's help-echo string is displayed.
Any button with a non-nil `skip' property is skipped over.
Returns the button found."
  (interactive "p\nd\nd")
  (let (button)
    (if (zerop n)
	;; Move to start of current button
	(if (setq button (button-at (point)))
	    (goto-char (button-start button)))
      ;; Move to Nth next button
      (let ((iterator (if (> n 0) #'next-button #'previous-button))
	    (wrap-start (if (> n 0) (point-min) (point-max)))
	    opoint fail)
	(setq n (abs n))
	(setq button t)			; just to start the loop
	(while (and (null fail) (> n 0) button)
	  (setq button (funcall iterator (point)))
	  (when (and (not button) wrap)
	    (setq button (funcall iterator wrap-start t)))
	  (when button
	    (goto-char (button-start button))
	    ;; Avoid looping forever (e.g., if all the buttons have
	    ;; the `skip' property).
	    (cond ((null opoint)
		   (setq opoint (point)))
		  ((= opoint (point))
		   (setq fail t)))
	    (unless (button-get button 'skip)
	      (setq n (1- n)))))))
    (if (null button)
	(error (if wrap "No buttons!" "No more buttons"))
      (let ((msg (and display-message (button-get button 'help-echo))))
	(when msg
	  (message "%s" msg)))
      button)))

(defun backward-button (n &optional wrap display-message)
  "Move to the Nth previous button, or Nth next button if N is negative.
If N is 0, move to the start of any button at point.
If WRAP is non-nil, moving past either end of the buffer continues from the
other end.
If DISPLAY-MESSAGE is non-nil, the button's help-echo string is displayed.
Any button with a non-nil `skip' property is skipped over.
Returns the button found."
  (interactive "p\nd\nd")
  (forward-button (- n) wrap display-message))


(provide 'button)

;; arch-tag: 5f2c7627-413b-4097-b282-630f89d9c5e9
;;; button.el ends here
Tip: Filter by directory path e.g. /media app.js to search for public/media/app.js.
Tip: Use camelCasing e.g. ProjME to search for ProjectModifiedEvent.java.
Tip: Filter by extension type e.g. /repo .js to search for all .js files in the /repo directory.
Tip: Separate your search with spaces e.g. /ssh pom.xml to search for src/ssh/pom.xml.
Tip: Use ↑ and ↓ arrow keys to navigate and return to view the file.
Tip: You can also navigate files with Ctrl+j (next) and Ctrl+k (previous) and view the file with Ctrl+o.
Tip: You can also navigate files with Alt+j (next) and Alt+k (previous) and view the file with Alt+o.