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5e28918b | 1 | ;;; paren.el --- highlight matching paren. |
e788f291 | 2 | ;; Copyright (C) 1993 Free Software Foundation, Inc. |
5e28918b | 3 | |
5e2325c9 JB |
4 | ;;; Author: rms@gnu.ai.mit.edu |
5 | ;;; Maintainer: FSF | |
6 | ;;; Keywords: languages, faces | |
7 | ||
5e28918b JB |
8 | ;; This file is part of GNU Emacs. |
9 | ||
10 | ;; GNU Emacs is free software; you can redistribute it and/or modify | |
11 | ;; it under the terms of the GNU General Public License as published by | |
12 | ;; the Free Software Foundation; either version 2, or (at your option) | |
13 | ;; any later version. | |
14 | ||
15 | ;; GNU Emacs is distributed in the hope that it will be useful, | |
16 | ;; but WITHOUT ANY WARRANTY; without even the implied warranty of | |
17 | ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
18 | ;; GNU General Public License for more details. | |
19 | ||
20 | ;; You should have received a copy of the GNU General Public License | |
21 | ;; along with GNU Emacs; see the file COPYING. If not, write to | |
22 | ;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. | |
23 | ||
24 | ;;; Commentary: | |
25 | ||
26 | ;; Load this and it will display highlighting on whatever | |
27 | ;; paren matches the one before or after point. | |
28 | ||
29 | ;;; Code: | |
30 | ||
d1475aa1 | 31 | (defvar show-paren-overlay nil) |
5e28918b | 32 | |
d1475aa1 JB |
33 | ;; Find the place to show, if there is one, |
34 | ;; and show it until input arrives. | |
35 | (defun show-paren-command-hook () | |
5e28918b JB |
36 | (let (pos dir mismatch (oldpos (point)) |
37 | (face (if (face-equal 'highlight 'region) | |
38 | 'underline 'highlight))) | |
39 | (cond ((eq (char-syntax (following-char)) ?\() | |
40 | (setq dir 1)) | |
41 | ((eq (char-syntax (preceding-char)) ?\)) | |
42 | (setq dir -1))) | |
43 | (save-excursion | |
44 | (save-restriction | |
45 | ;; Determine the range within which to look for a match. | |
46 | (if blink-matching-paren-distance | |
47 | (narrow-to-region (max (point-min) | |
48 | (- (point) blink-matching-paren-distance)) | |
49 | (min (point-max) | |
50 | (+ (point) blink-matching-paren-distance)))) | |
51 | ;; Scan across one sexp within that range. | |
52 | (condition-case () | |
53 | (setq pos (scan-sexps (point) dir)) | |
54 | (error nil)) | |
55 | ;; See if the "matching" paren is the right kind of paren | |
56 | ;; to match the one we started at. | |
57 | (if pos | |
58 | (let ((beg (min pos oldpos)) (end (max pos oldpos))) | |
59 | (and (/= (char-syntax (char-after beg)) ?\$) | |
60 | (setq mismatch | |
61 | (/= (char-after (1- end)) | |
62 | (logand (lsh (aref (syntax-table) | |
63 | (char-after beg)) | |
64 | -8) | |
65 | 255)))))) | |
d1475aa1 | 66 | ;; If they don't properly match, don't show. |
5e28918b | 67 | (if mismatch |
5e2325c9 JB |
68 | (progn |
69 | (message "Paren mismatch") | |
70 | ;;; (setq pos nil) | |
71 | )))) | |
5e28918b | 72 | (cond (pos |
d1475aa1 JB |
73 | (if show-paren-overlay |
74 | (move-overlay show-paren-overlay (- pos dir) pos) | |
75 | (setq show-paren-overlay | |
5e28918b | 76 | (make-overlay (- pos dir) pos))) |
d1475aa1 | 77 | (overlay-put show-paren-overlay 'face face) |
5e28918b JB |
78 | ;;; This is code to blink the highlighting. |
79 | ;;; It is desirable to avoid this because | |
80 | ;;; it would interfere with auto-save and gc when idle. | |
81 | ;;; (while (sit-for 1) | |
d1475aa1 | 82 | ;;; (overlay-put show-paren-overlay |
5e28918b | 83 | ;;; 'face |
d1475aa1 | 84 | ;;; (if (overlay-get show-paren-overlay |
5e28918b JB |
85 | ;;; 'face) |
86 | ;;; nil face))) | |
87 | ) | |
88 | (t | |
d1475aa1 JB |
89 | (and show-paren-overlay (overlay-buffer show-paren-overlay) |
90 | (delete-overlay show-paren-overlay)))))) | |
5e28918b | 91 | |
d1475aa1 | 92 | (add-hook 'post-command-hook 'show-paren-command-hook) |
5e28918b | 93 | |
3a3236d2 JB |
94 | (provide 'paren) |
95 | ||
96 | ;;; paren.el ends here |