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;;; blink-paren.el --- blink the matching paren, just like Zmacs
;; Copyright (C) 1992, 1993, 1994 Free Software Foundation, Inc.
;; Author: devin@lucid.com.
;; Keywords: faces
;; This file is part of XEmacs.
;; XEmacs 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 2, or (at your option)
;; any later version.
;; XEmacs 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 XEmacs; see the file COPYING. If not, write to the
;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
;; Boston, MA 02111-1307, USA.
;;; Synched up with: Not in FSF.
(defvar blink-paren-timeout 0.2
"*If the cursor is on a parenthesis, the matching parenthesis will blink.
This variable controls how long each phase of the blink lasts in seconds.
This should be a fractional part of a second (a float.)")
(defvar highlight-paren-expression nil
"*If true, highlight the whole expression of the paren under the cursor
instead of blinking (or highlighting) the matching paren. This will highlight
the expression using the `highlight-expression' face.")
;;; The blinking paren alternates between the faces blink-paren-on and
;;; blink-paren-off. The default is for -on to look just like default
;;; text, and -off to be invisible. You can change this so that, for
;;; example, the blinking paren fluctuates between bold and italic...
;;;
;;; You can make the matching paren merely be highlighted (and not blink)
;;; by setting the blink-paren-on and blink-paren-off faces to have the same
;;; attributes; if you do this, then emacs will not consume as much CPU.
;;;
;;; If highlight-paren-expression is true, then the whole sexp between the
;;; parens will be displayed in the `highlight-expression' face instead.
(make-face 'blink-paren-on)
(make-face 'blink-paren-off)
(make-face 'highlight-expression)
;; extent used to change the face of the matching paren
(defvar blink-paren-extent nil)
;; timeout to blink the face
(defvar blink-paren-timeout-id nil)
;; find if we should look foward or backward to find the matching paren
(defun blink-paren-sexp-dir ()
(cond ((and (< (point) (point-max))
(eq (char-syntax (char-after (point))) ?\())
1)
((and (> (point) (point-min))
(eq (char-syntax (char-after (- (point) 1))) ?\)))
-1)
(t ())))
;; make an extent on the matching paren if any. return it.
(defun blink-paren-make-extent ()
(let ((dir (blink-paren-sexp-dir)))
(and dir
(condition-case ()
(let* ((parse-sexp-ignore-comments t)
(other-pos (let ((pmin (point-min))
(pmax (point-max))
(point (point)))
(unwind-protect
(progn
(narrow-to-region
(max pmin (- point blink-matching-paren-distance))
(min pmax (+ point blink-matching-paren-distance)))
(forward-sexp dir) (point))
(narrow-to-region pmin pmax)
(goto-char point))))
(extent (if (= dir 1)
(make-extent (if highlight-paren-expression
(point)
(- other-pos 1))
other-pos)
(make-extent other-pos
(if highlight-paren-expression
(point)
(+ other-pos 1))))))
(set-extent-face extent (if highlight-paren-expression
'highlight-expression
'blink-paren-on))
extent)
(error nil)))))
;; callback for the timeout
;; swap the face of the extent on the matching paren
(defun blink-paren-timeout (arg)
;; The extent could have been deleted for some reason and not point to a
;; buffer anymore. So catch any error to remove the timeout.
(condition-case ()
(set-extent-face blink-paren-extent
(if (eq (extent-face blink-paren-extent)
'blink-paren-on)
'blink-paren-off
'blink-paren-on))
(error (blink-paren-pre-command))))
;; called after each command is executed in the post-command-hook
;; add the extent and the time-out if we are on a paren.
(defun blink-paren-post-command ()
(blink-paren-pre-command)
(if (and (setq blink-paren-extent (blink-paren-make-extent))
(not highlight-paren-expression)
(not (and (face-equal 'blink-paren-on 'blink-paren-off)
(progn
(set-extent-face blink-paren-extent 'blink-paren-on)
t)))
(or (floatp blink-paren-timeout)
(integerp blink-paren-timeout)))
(setq blink-paren-timeout-id
(add-timeout blink-paren-timeout 'blink-paren-timeout ()
blink-paren-timeout))))
;; called before a new command is executed in the pre-command-hook
;; cleanup by removing the extent and the time-out
(defun blink-paren-pre-command ()
(condition-case c ; don't ever signal an error in pre-command-hook!
(let ((inhibit-quit t))
(if blink-paren-timeout-id
(disable-timeout (prog1 blink-paren-timeout-id
(setq blink-paren-timeout-id nil))))
(if blink-paren-extent
(delete-extent (prog1 blink-paren-extent
(setq blink-paren-extent nil)))))
(error
(message "blink paren error! %s" c))))
(defun blink-paren (&optional arg)
"Toggles paren blinking on and off.
With a positive argument, turns it on.
With a non-positive argument, turns it off."
(interactive "P")
(let* ((was-on (not (not (memq 'blink-paren-pre-command pre-command-hook))))
(on-p (if (null arg)
(not was-on)
(> (prefix-numeric-value arg) 0))))
(cond (on-p
;; in case blink paren was dumped, this needs to be setup
(or (face-differs-from-default-p 'blink-paren-off)
(progn
(set-face-background 'blink-paren-off (face-background 'default))
(set-face-foreground 'blink-paren-off (face-background 'default))))
(or (face-differs-from-default-p 'highlight-expression)
(set-face-underline-p 'highlight-expression t))
(add-hook 'pre-command-hook 'blink-paren-pre-command)
(add-hook 'post-command-hook 'blink-paren-post-command)
(setq blink-matching-paren nil))
(t
(remove-hook 'pre-command-hook 'blink-paren-pre-command)
(remove-hook 'post-command-hook 'blink-paren-post-command)
(and blink-paren-extent (detach-extent blink-paren-extent))
(setq blink-matching-paren t)))
on-p))
(defun blink-paren-init ()
"obsolete - use `blink-paren' instead."
(interactive)
(blink-paren 1))
(provide 'blink-paren)
(blink-paren 1)
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