1;;; paren.el --- highlight matching paren
2
3;; Copyright (C) 1993, 1996, 2001, 2002, 2003, 2004,
4;;   2005, 2006, 2007 Free Software Foundation, Inc.
5
6;; Author: rms@gnu.org
7;; Maintainer: FSF
8;; Keywords: languages, faces
9
10;; This file is part of GNU Emacs.
11
12;; GNU Emacs is free software; you can redistribute it and/or modify
13;; it under the terms of the GNU General Public License as published by
14;; the Free Software Foundation; either version 2, or (at your option)
15;; any later version.
16
17;; GNU Emacs is distributed in the hope that it will be useful,
18;; but WITHOUT ANY WARRANTY; without even the implied warranty of
19;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
20;; GNU General Public License for more details.
21
22;; You should have received a copy of the GNU General Public License
23;; along with GNU Emacs; see the file COPYING.  If not, write to the
24;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
25;; Boston, MA 02110-1301, USA.
26
27;;; Commentary:
28
29;; Put this into your ~/.emacs:
30
31;;  (show-paren-mode t)
32
33;; It will display highlighting on whatever paren matches the one
34;; before or after point.
35
36;;; Code:
37
38(defgroup paren-showing nil
39  "Showing (un)matching of parens and expressions."
40  :prefix "show-paren-"
41  :group 'paren-matching)
42
43;; This is the overlay used to highlight the matching paren.
44(defvar show-paren-overlay nil)
45;; This is the overlay used to highlight the closeparen right before point.
46(defvar show-paren-overlay-1 nil)
47
48(defcustom show-paren-style 'parenthesis
49  "*Style used when showing a matching paren.
50Valid styles are `parenthesis' (meaning show the matching paren),
51`expression' (meaning show the entire expression enclosed by the paren) and
52`mixed' (meaning show the matching paren if it is visible, and the expression
53otherwise)."
54  :type '(choice (const parenthesis) (const expression) (const mixed))
55  :group 'paren-showing)
56
57(defcustom show-paren-delay
58  (if (featurep 'lisp-float-type) (/ (float 1) (float 8)) 1)
59  "*Time in seconds to delay before showing a matching paren."
60  :type '(number :tag "seconds")
61  :group 'paren-showing)
62
63(defcustom show-paren-priority 1000
64  "*Priority of paren highlighting overlays."
65  :type 'integer
66  :group 'paren-showing
67  :version "21.1")
68
69(defcustom show-paren-ring-bell-on-mismatch nil
70  "*If non-nil, beep if mismatched paren is detected."
71  :type 'boolean
72  :group 'paren-showing
73  :version "20.3")
74
75(defgroup paren-showing-faces nil
76  "Group for faces of Show Paren mode."
77  :group 'paren-showing
78  :group 'faces
79  :version "22.1")
80
81(defface show-paren-match
82  '((((class color) (background light))
83     :background "turquoise")		; looks OK on tty (becomes cyan)
84    (((class color) (background dark))
85     :background "steelblue3")		; looks OK on tty (becomes blue)
86    (((background dark))
87     :background "grey50")
88    (t
89     :background "gray"))
90  "Show Paren mode face used for a matching paren."
91  :group 'paren-showing-faces)
92;; backward-compatibility alias
93(put 'show-paren-match-face 'face-alias 'show-paren-match)
94
95(defface show-paren-mismatch
96  '((((class color)) (:foreground "white" :background "purple"))
97    (t (:inverse-video t)))
98  "Show Paren mode face used for a mismatching paren."
99  :group 'paren-showing-faces)
100;; backward-compatibility alias
101(put 'show-paren-mismatch-face 'face-alias 'show-paren-mismatch)
102
103(defvar show-paren-highlight-openparen t
104  "*Non-nil turns on openparen highlighting when matching forward.")
105
106(defvar show-paren-idle-timer nil)
107
108;;;###autoload
109(define-minor-mode show-paren-mode
110  "Toggle Show Paren mode.
111With prefix ARG, turn Show Paren mode on if and only if ARG is positive.
112Returns the new status of Show Paren mode (non-nil means on).
113
114When Show Paren mode is enabled, any matching parenthesis is highlighted
115in `show-paren-style' after `show-paren-delay' seconds of Emacs idle time."
116  :global t :group 'paren-showing
117    ;; Enable or disable the mechanism.
118    ;; First get rid of the old idle timer.
119    (if show-paren-idle-timer
120	(cancel-timer show-paren-idle-timer))
121    (setq show-paren-idle-timer nil)
122    ;; If show-paren-mode is enabled in some buffer now,
123    ;; set up a new timer.
124    (when (memq t (mapcar (lambda (buffer)
125			    (with-current-buffer buffer
126			      show-paren-mode))
127			  (buffer-list)))
128      (setq show-paren-idle-timer (run-with-idle-timer
129				   show-paren-delay t
130				   'show-paren-function)))
131    (unless show-paren-mode
132      (and show-paren-overlay
133	   (eq (overlay-buffer show-paren-overlay) (current-buffer))
134	   (delete-overlay show-paren-overlay))
135      (and show-paren-overlay-1
136	   (eq (overlay-buffer show-paren-overlay-1) (current-buffer))
137	   (delete-overlay show-paren-overlay-1))))
138
139;; Find the place to show, if there is one,
140;; and show it until input arrives.
141(defun show-paren-function ()
142  (if show-paren-mode
143      (let ((oldpos (point))
144	    (dir (cond ((eq (syntax-class (syntax-after (1- (point)))) 5) -1)
145                       ((eq (syntax-class (syntax-after (point)))      4) 1)))
146	    pos mismatch face)
147	;;
148	;; Find the other end of the sexp.
149	(when dir
150	  (save-excursion
151	    (save-restriction
152	      ;; Determine the range within which to look for a match.
153	      (when blink-matching-paren-distance
154		(narrow-to-region
155		 (max (point-min) (- (point) blink-matching-paren-distance))
156		 (min (point-max) (+ (point) blink-matching-paren-distance))))
157	      ;; Scan across one sexp within that range.
158	      ;; Errors or nil mean there is a mismatch.
159	      (condition-case ()
160		  (setq pos (scan-sexps (point) dir))
161		(error (setq pos t mismatch t)))
162	      ;; Move back the other way and verify we get back to the
163	      ;; starting point.  If not, these two parens don't really match.
164	      ;; Maybe the one at point is escaped and doesn't really count.
165	      (when (integerp pos)
166		(unless (condition-case ()
167			    (eq (point) (scan-sexps pos (- dir)))
168			  (error nil))
169		  (setq pos nil)))
170	      ;; If found a "matching" paren, see if it is the right
171	      ;; kind of paren to match the one we started at.
172	      (when (integerp pos)
173		(let ((beg (min pos oldpos)) (end (max pos oldpos)))
174		  (unless (eq (syntax-class (syntax-after beg)) 8)
175		    (setq mismatch
176			  (not (or (eq (char-before end)
177				       ;; This can give nil.
178				       (cdr (syntax-after beg)))
179				   (eq (char-after beg)
180				       ;; This can give nil.
181				       (cdr (syntax-after (1- end))))
182                                   ;; The cdr might hold a new paren-class
183                                   ;; info rather than a matching-char info,
184                                   ;; in which case the two CDRs should match.
185                                   (eq (cdr (syntax-after (1- end)))
186                                       (cdr (syntax-after beg))))))))))))
187	;;
188	;; Highlight the other end of the sexp, or unhighlight if none.
189	(if (not pos)
190	    (progn
191	      ;; If not at a paren that has a match,
192	      ;; turn off any previous paren highlighting.
193	      (and show-paren-overlay (overlay-buffer show-paren-overlay)
194		   (delete-overlay show-paren-overlay))
195	      (and show-paren-overlay-1 (overlay-buffer show-paren-overlay-1)
196		   (delete-overlay show-paren-overlay-1)))
197	  ;;
198	  ;; Use the correct face.
199	  (if mismatch
200	      (progn
201		(if show-paren-ring-bell-on-mismatch
202		    (beep))
203		(setq face 'show-paren-mismatch))
204	    (setq face 'show-paren-match))
205	  ;;
206	  ;; If matching backwards, highlight the closeparen
207	  ;; before point as well as its matching open.
208	  ;; If matching forward, and the openparen is unbalanced,
209	  ;; highlight the paren at point to indicate misbalance.
210	  ;; Otherwise, turn off any such highlighting.
211	  (if (and (not show-paren-highlight-openparen) (= dir 1) (integerp pos))
212	      (when (and show-paren-overlay-1
213			 (overlay-buffer show-paren-overlay-1))
214		(delete-overlay show-paren-overlay-1))
215	    (let ((from (if (= dir 1)
216			    (point)
217			  (forward-point -1)))
218		  (to (if (= dir 1)
219			  (forward-point 1)
220			(point))))
221	      (if show-paren-overlay-1
222		  (move-overlay show-paren-overlay-1 from to (current-buffer))
223		(setq show-paren-overlay-1 (make-overlay from to nil t)))
224	      ;; Always set the overlay face, since it varies.
225	      (overlay-put show-paren-overlay-1 'priority show-paren-priority)
226	      (overlay-put show-paren-overlay-1 'face face)))
227	  ;;
228	  ;; Turn on highlighting for the matching paren, if found.
229	  ;; If it's an unmatched paren, turn off any such highlighting.
230	  (unless (integerp pos)
231	    (delete-overlay show-paren-overlay))
232	  (let ((to (if (or (eq show-paren-style 'expression)
233			    (and (eq show-paren-style 'mixed)
234				 (not (pos-visible-in-window-p pos))))
235			(point)
236		      pos))
237		(from (if (or (eq show-paren-style 'expression)
238			      (and (eq show-paren-style 'mixed)
239				   (not (pos-visible-in-window-p pos))))
240			  pos
241			(save-excursion
242			  (goto-char pos)
243			  (forward-point (- dir))))))
244	    (if show-paren-overlay
245		(move-overlay show-paren-overlay from to (current-buffer))
246	      (setq show-paren-overlay (make-overlay from to nil t))))
247	  ;;
248	  ;; Always set the overlay face, since it varies.
249	  (overlay-put show-paren-overlay 'priority show-paren-priority)
250	  (overlay-put show-paren-overlay 'face face)))
251    ;; show-paren-mode is nil in this buffer.
252    (and show-paren-overlay
253	 (delete-overlay show-paren-overlay))
254    (and show-paren-overlay-1
255	 (delete-overlay show-paren-overlay-1))))
256
257(provide 'paren)
258
259;; arch-tag: d0969b88-7ac0-4bd0-bd53-e73b892b86a9
260;;; paren.el ends here
261