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97 lines
3.0 KiB
EmacsLisp
97 lines
3.0 KiB
EmacsLisp
;;; paren.el --- highlight matching paren.
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;; Copyright (C) 1993 Free Software Foundation, Inc.
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;; Author: rms@gnu.ai.mit.edu
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;; Maintainer: FSF
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;; Keywords: languages, faces
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;; This file is part of GNU Emacs.
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;; GNU Emacs is free software; you can redistribute it and/or modify
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;; it under the terms of the GNU General Public License as published by
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;; the Free Software Foundation; either version 2, or (at your option)
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;; any later version.
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;; GNU Emacs is distributed in the hope that it will be useful,
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;; but WITHOUT ANY WARRANTY; without even the implied warranty of
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;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;; GNU General Public License for more details.
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;; You should have received a copy of the GNU General Public License
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;; along with GNU Emacs; see the file COPYING. If not, write to
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;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
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;;; Commentary:
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;; Load this and it will display highlighting on whatever
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;; paren matches the one before or after point.
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;;; Code:
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(defvar show-paren-overlay nil)
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;; Find the place to show, if there is one,
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;; and show it until input arrives.
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(defun show-paren-command-hook ()
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(let (pos dir mismatch (oldpos (point))
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(face (if (face-equal 'highlight 'region)
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'underline 'highlight)))
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(cond ((eq (char-syntax (following-char)) ?\()
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(setq dir 1))
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((eq (char-syntax (preceding-char)) ?\))
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(setq dir -1)))
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(save-excursion
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(save-restriction
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;; Determine the range within which to look for a match.
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(if blink-matching-paren-distance
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(narrow-to-region (max (point-min)
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(- (point) blink-matching-paren-distance))
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(min (point-max)
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(+ (point) blink-matching-paren-distance))))
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;; Scan across one sexp within that range.
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(condition-case ()
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(setq pos (scan-sexps (point) dir))
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(error nil))
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;; See if the "matching" paren is the right kind of paren
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;; to match the one we started at.
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(if pos
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(let ((beg (min pos oldpos)) (end (max pos oldpos)))
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(and (/= (char-syntax (char-after beg)) ?\$)
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(setq mismatch
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(/= (char-after (1- end))
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(logand (lsh (aref (syntax-table)
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(char-after beg))
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-8)
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255))))))
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;; If they don't properly match, don't show.
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(if mismatch
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(progn
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(message "Paren mismatch")
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;;; (setq pos nil)
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))))
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(cond (pos
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(if show-paren-overlay
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(move-overlay show-paren-overlay (- pos dir) pos)
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(setq show-paren-overlay
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(make-overlay (- pos dir) pos)))
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(overlay-put show-paren-overlay 'face face)
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;;; This is code to blink the highlighting.
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;;; It is desirable to avoid this because
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;;; it would interfere with auto-save and gc when idle.
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;;; (while (sit-for 1)
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;;; (overlay-put show-paren-overlay
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;;; 'face
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;;; (if (overlay-get show-paren-overlay
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;;; 'face)
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;;; nil face)))
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)
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(t
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(and show-paren-overlay (overlay-buffer show-paren-overlay)
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(delete-overlay show-paren-overlay))))))
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(add-hook 'post-command-hook 'show-paren-command-hook)
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(provide 'paren)
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;;; paren.el ends here
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