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[emacs.git] / lisp / paren.el
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1 ;;; paren.el --- highlight matching paren.
3 ;; Copyright (C) 1993, 1996 Free Software Foundation, Inc.
5 ;; Author: rms@gnu.org
6 ;; Maintainer: FSF
7 ;; Keywords: languages, faces
9 ;; This file is part of GNU Emacs.
11 ;; GNU Emacs is free software; you can redistribute it and/or modify
12 ;; it under the terms of the GNU General Public License as published by
13 ;; the Free Software Foundation; either version 2, or (at your option)
14 ;; any later version.
16 ;; GNU Emacs is distributed in the hope that it will be useful,
17 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
18 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19 ;; GNU General Public License for more details.
21 ;; You should have received a copy of the GNU General Public License
22 ;; along with GNU Emacs; see the file COPYING. If not, write to the
23 ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
24 ;; Boston, MA 02111-1307, USA.
26 ;;; Commentary:
28 ;; Load this and it will display highlighting on whatever
29 ;; paren matches the one before or after point.
31 ;;; Code:
33 (defgroup paren-showing nil
34 "Showing (un)matching of parens and expressions."
35 :prefix "show-paren-"
36 :group 'paren-matching)
38 ;; This is the overlay used to highlight the matching paren.
39 (defvar show-paren-overlay nil)
40 ;; This is the overlay used to highlight the closeparen right before point.
41 (defvar show-paren-overlay-1 nil)
43 ;;;###autoload
44 (defcustom show-paren-mode nil
45 "*Toggle Show Paren mode.
46 When Show Paren mode is enabled, any matching parenthesis is highlighted
47 after `show-paren-delay' seconds of Emacs idle time.
48 Setting this variable directly does not take effect;
49 use either \\[customize] or the function `show-paren-mode'."
50 :set (lambda (symbol value)
51 (show-paren-mode (or value 0)))
52 :initialize 'custom-initialize-default
53 :type 'boolean
54 :group 'paren-showing
55 :require 'paren)
57 (defcustom show-paren-style 'parenthesis
58 "*Style used when showing a matching paren.
59 Valid styles are `parenthesis' (meaning show the matching paren),
60 `expression' (meaning show the entire expression enclosed by the paren) and
61 `mixed' (meaning show the matching paren if it is visible, and the expression
62 otherwise)."
63 :type '(choice (const parenthesis) (const expression) (const mixed))
64 :group 'paren-showing)
66 (defcustom show-paren-delay
67 (if (featurep 'lisp-float-type) (/ (float 1) (float 8)) 1)
68 "*Time in seconds to delay before showing a matching paren."
69 :type '(number :tag "seconds")
70 :group 'paren-showing)
72 (defcustom show-paren-ring-bell-on-mismatch nil
73 "*If non-nil, beep if mismatched paren is detected."
74 :type 'boolean
75 :group 'paren-showing
76 :version "20.3")
78 (defface show-paren-match-face
79 '((((class color)) (:background "turquoise"))
80 (t (:background "gray")))
81 "Show Paren mode face used for a matching paren."
82 :group 'faces
83 :group 'paren-showing)
85 (defface show-paren-mismatch-face
86 '((((class color)) (:foreground "white" :background "purple"))
87 (t (:reverse-video t)))
88 "Show Paren mode face used for a mismatching paren."
89 :group 'faces
90 :group 'paren-showing)
92 (defvar show-paren-idle-timer nil)
94 ;;;###autoload
95 (defun show-paren-mode (&optional arg)
96 "Toggle Show Paren mode.
97 With prefix ARG, turn Show Paren mode on if and only if ARG is positive.
98 Returns the new status of Show Paren mode (non-nil means on).
100 When Show Paren mode is enabled, any matching parenthesis is highlighted
101 in `show-paren-style' after `show-paren-delay' seconds of Emacs idle time."
102 (interactive "P")
103 (let ((on-p (if arg
104 (> (prefix-numeric-value arg) 0)
105 (not show-paren-mode))))
106 (setq show-paren-mode on-p)
107 ;; Turn off the usual paren-matching method
108 ;; when this one is turned on.
109 (if (local-variable-p 'show-paren-mode)
110 (make-local-variable 'blink-matching-paren-on-screen)
111 (kill-local-variable 'blink-matching-paren-on-screen))
112 (setq blink-matching-paren-on-screen (not on-p))
114 ;; Now enable or disable the mechanism.
115 ;; First get rid of the old idle timer.
116 (if show-paren-idle-timer
117 (cancel-timer show-paren-idle-timer))
118 (setq show-paren-idle-timer nil)
119 ;; If show-paren-mode is enabled in some buffer now,
120 ;; set up a new timer.
121 (when (memq t (mapcar (lambda (buffer)
122 (with-current-buffer buffer
123 show-paren-mode))
124 (buffer-list)))
125 (setq show-paren-idle-timer (run-with-idle-timer
126 show-paren-delay t
127 'show-paren-function)))
128 (unless on-p
129 (and show-paren-overlay
130 (eq (overlay-buffer show-paren-overlay) (current-buffer))
131 (delete-overlay show-paren-overlay))
132 (and show-paren-overlay-1
133 (eq (overlay-buffer show-paren-overlay-1) (current-buffer))
134 (delete-overlay show-paren-overlay-1)))))
136 ;; Find the place to show, if there is one,
137 ;; and show it until input arrives.
138 (defun show-paren-function ()
139 (if show-paren-mode
140 (let (pos dir mismatch face (oldpos (point)))
141 (cond ((eq (char-syntax (preceding-char)) ?\))
142 (setq dir -1))
143 ((eq (char-syntax (following-char)) ?\()
144 (setq dir 1)))
146 ;; Find the other end of the sexp.
147 (when dir
148 (save-excursion
149 (save-restriction
150 ;; Determine the range within which to look for a match.
151 (when blink-matching-paren-distance
152 (narrow-to-region
153 (max (point-min) (- (point) blink-matching-paren-distance))
154 (min (point-max) (+ (point) blink-matching-paren-distance))))
155 ;; Scan across one sexp within that range.
156 ;; Errors or nil mean there is a mismatch.
157 (condition-case ()
158 (setq pos (scan-sexps (point) dir))
159 (error (setq pos t mismatch t)))
160 ;; If found a "matching" paren, see if it is the right
161 ;; kind of paren to match the one we started at.
162 (when (integerp pos)
163 (let ((beg (min pos oldpos)) (end (max pos oldpos)))
164 (when (/= (char-syntax (char-after beg)) ?\$)
165 (setq mismatch
166 (not (eq (char-before end)
167 ;; This can give nil.
168 (matching-paren (char-after beg)))))))))))
170 ;; Highlight the other end of the sexp, or unhighlight if none.
171 (if (not pos)
172 (progn
173 ;; If not at a paren that has a match,
174 ;; turn off any previous paren highlighting.
175 (and show-paren-overlay (overlay-buffer show-paren-overlay)
176 (delete-overlay show-paren-overlay))
177 (and show-paren-overlay-1 (overlay-buffer show-paren-overlay-1)
178 (delete-overlay show-paren-overlay-1)))
180 ;; Use the correct face.
181 (if mismatch
182 (progn
183 (if show-paren-ring-bell-on-mismatch
184 (beep))
185 (setq face 'show-paren-mismatch-face))
186 (setq face 'show-paren-match-face))
188 ;; If matching backwards, highlight the closeparen
189 ;; before point as well as its matching open.
190 ;; If matching forward, and the openparen is unbalanced,
191 ;; highlight the paren at point to indicate misbalance.
192 ;; Otherwise, turn off any such highlighting.
193 (if (and (= dir 1) (integerp pos))
194 (when (and show-paren-overlay-1
195 (overlay-buffer show-paren-overlay-1))
196 (delete-overlay show-paren-overlay-1))
197 (let ((from (if (= dir 1)
198 (point)
199 (forward-point -1)))
200 (to (if (= dir 1)
201 (forward-point 1)
202 (point))))
203 (if show-paren-overlay-1
204 (move-overlay show-paren-overlay-1 from to (current-buffer))
205 (setq show-paren-overlay-1 (make-overlay from to)))
206 ;; Always set the overlay face, since it varies.
207 (overlay-put show-paren-overlay-1 'face face)))
209 ;; Turn on highlighting for the matching paren, if found.
210 ;; If it's an unmatched paren, turn off any such highlighting.
211 (unless (integerp pos)
212 (delete-overlay show-paren-overlay))
213 (let ((to (if (or (eq show-paren-style 'expression)
214 (and (eq show-paren-style 'mixed)
215 (not (pos-visible-in-window-p pos))))
216 (point)
217 pos))
218 (from (if (or (eq show-paren-style 'expression)
219 (and (eq show-paren-style 'mixed)
220 (not (pos-visible-in-window-p pos))))
222 (save-excursion
223 (goto-char pos)
224 (forward-point (- dir))))))
225 (if show-paren-overlay
226 (move-overlay show-paren-overlay from to (current-buffer))
227 (setq show-paren-overlay (make-overlay from to))))
229 ;; Always set the overlay face, since it varies.
230 (overlay-put show-paren-overlay 'face face)))
231 ;; show-paren-mode is nil in this buffer.
232 (and show-paren-overlay
233 (delete-overlay show-paren-overlay))
234 (and show-paren-overlay-1
235 (delete-overlay show-paren-overlay-1))))
237 (provide 'paren)
239 (if show-paren-mode
240 (show-paren-mode t))
242 ;;; paren.el ends here