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a51ab2f357
* lisp/paren.el: Use lexical-binding. (show-paren--default): Use imperative form in doc-string. * test/lisp/paren-tests.el: New file with tests for paren.el.
298 lines
11 KiB
EmacsLisp
298 lines
11 KiB
EmacsLisp
;;; paren.el --- highlight matching paren -*- lexical-binding:t -*-
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;; Copyright (C) 1993, 1996, 2001-2019 Free Software Foundation, Inc.
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;; Author: rms@gnu.org
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;; Maintainer: emacs-devel@gnu.org
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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 3 of the License, or
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;; (at your option) 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. If not, see <https://www.gnu.org/licenses/>.
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;;; Commentary:
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;; Put this into your ~/.emacs:
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;; (show-paren-mode t)
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;; It will display highlighting on whatever paren matches the one
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;; before or after point.
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;;; Code:
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(defgroup paren-showing nil
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"Showing (un)matching of parens and expressions."
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:prefix "show-paren-"
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:group 'paren-matching)
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(defcustom show-paren-style 'parenthesis
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"Style used when showing a matching paren.
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Valid styles are `parenthesis' (meaning show the matching paren),
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`expression' (meaning show the entire expression enclosed by the paren) and
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`mixed' (meaning show the matching paren if it is visible, and the expression
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otherwise)."
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:type '(choice (const parenthesis) (const expression) (const mixed)))
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(defcustom show-paren-delay 0.125
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"Time in seconds to delay before showing a matching paren.
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If you change this without using customize while `show-paren-mode' is
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active, you must toggle the mode off and on again for this to take effect."
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:type '(number :tag "seconds")
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:initialize 'custom-initialize-default
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:set (lambda (sym val)
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(if (not show-paren-mode)
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(set sym val)
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(show-paren-mode -1)
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(set sym val)
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(show-paren-mode 1))))
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(defcustom show-paren-priority 1000
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"Priority of paren highlighting overlays."
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:type 'integer
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:version "21.1")
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(defcustom show-paren-ring-bell-on-mismatch nil
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"If non-nil, beep if mismatched paren is detected."
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:type 'boolean
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:version "20.3")
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(defcustom show-paren-when-point-inside-paren nil
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"If non-nil, show parens when point is just inside one.
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This will only be done when point isn't also just outside a paren."
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:type 'boolean
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:version "25.1")
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(defcustom show-paren-when-point-in-periphery nil
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"If non-nil, show parens when point is in the line's periphery.
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The periphery is at the beginning or end of a line or in any
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whitespace there."
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:type 'boolean
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:version "25.1")
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(defcustom show-paren-highlight-openparen t
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"Non-nil turns on openparen highlighting when matching forward.
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When nil, and point stands just before an open paren, the paren
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is not highlighted, the cursor being regarded as adequate to mark
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its position."
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:type 'boolean)
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(defvar show-paren--idle-timer nil)
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(defvar show-paren--overlay
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(let ((ol (make-overlay (point) (point) nil t))) (delete-overlay ol) ol)
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"Overlay used to highlight the matching paren.")
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(defvar show-paren--overlay-1
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(let ((ol (make-overlay (point) (point) nil t))) (delete-overlay ol) ol)
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"Overlay used to highlight the paren at point.")
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;;;###autoload
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(define-minor-mode show-paren-mode
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"Toggle visualization of matching parens (Show Paren mode).
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Show Paren mode is a global minor mode. When enabled, any
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matching parenthesis is highlighted in `show-paren-style' after
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`show-paren-delay' seconds of Emacs idle time."
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:global t :group 'paren-showing
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;; Enable or disable the mechanism.
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;; First get rid of the old idle timer.
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(when show-paren--idle-timer
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(cancel-timer show-paren--idle-timer)
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(setq show-paren--idle-timer nil))
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(setq show-paren--idle-timer (run-with-idle-timer
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show-paren-delay t
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#'show-paren-function))
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(unless show-paren-mode
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(delete-overlay show-paren--overlay)
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(delete-overlay show-paren--overlay-1)))
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(defun show-paren--unescaped-p (pos)
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"Determine whether the paren after POS is unescaped."
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(save-excursion
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(goto-char pos)
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(= (logand (skip-syntax-backward "/\\") 1) 0)))
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(defun show-paren--categorize-paren (pos)
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"Determine whether the character after POS has paren syntax,
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and if so, return a cons (DIR . OUTSIDE), where DIR is 1 for an
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open paren, -1 for a close paren, and OUTSIDE is the buffer
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position of the outside of the paren. If the character isn't a
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paren, or it is an escaped paren, return nil."
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(cond
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((and (eq (syntax-class (syntax-after pos)) 4)
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(show-paren--unescaped-p pos))
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(cons 1 pos))
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((and (eq (syntax-class (syntax-after pos)) 5)
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(show-paren--unescaped-p pos))
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(cons -1 (1+ pos)))))
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(defun show-paren--locate-near-paren ()
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"Locate an unescaped paren \"near\" point to show.
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If one is found, return the cons (DIR . OUTSIDE), where DIR is 1
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for an open paren, -1 for a close paren, and OUTSIDE is the buffer
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position of the outside of the paren. Otherwise return nil."
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(let* ((ind-pos (save-excursion (back-to-indentation) (point)))
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(eol-pos
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(save-excursion
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(end-of-line) (skip-chars-backward " \t" ind-pos) (point)))
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(before (show-paren--categorize-paren (1- (point))))
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(after (show-paren--categorize-paren (point))))
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(cond
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;; Point is immediately outside a paren.
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((eq (car before) -1) before)
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((eq (car after) 1) after)
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;; Point is immediately inside a paren.
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((and show-paren-when-point-inside-paren before))
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((and show-paren-when-point-inside-paren after))
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;; Point is in the whitespace before the code.
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((and show-paren-when-point-in-periphery
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(<= (point) ind-pos))
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(or (show-paren--categorize-paren ind-pos)
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(show-paren--categorize-paren (1- eol-pos))))
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;; Point is in the whitespace after the code.
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((and show-paren-when-point-in-periphery
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(>= (point) eol-pos))
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(show-paren--categorize-paren (1- eol-pos))))))
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(defvar show-paren-data-function #'show-paren--default
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"Function to find the opener/closer \"near\" point and its match.
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The function is called with no argument and should return either nil
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if there's no opener/closer near point, or a list of the form
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\(HERE-BEG HERE-END THERE-BEG THERE-END MISMATCH)
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Where HERE-BEG..HERE-END is expected to be near point.")
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(defun show-paren--default ()
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"Find the opener/closer near point and its match.
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It is the default value of `show-paren-data-function'."
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(let* ((temp (show-paren--locate-near-paren))
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(dir (car temp))
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(outside (cdr temp))
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pos mismatch here-beg here-end)
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;;
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;; Find the other end of the sexp.
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(when dir
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(setq here-beg (if (eq dir 1) outside (1- outside))
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here-end (if (eq dir 1) (1+ outside) outside))
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(save-restriction
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;; Determine the range within which to look for a match.
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(when blink-matching-paren-distance
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(narrow-to-region
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(max (point-min) (- (point) blink-matching-paren-distance))
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(min (point-max) (+ (point) blink-matching-paren-distance))))
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;; Scan across one sexp within that range.
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;; Errors or nil mean there is a mismatch.
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(condition-case ()
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(setq pos (scan-sexps outside dir))
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(error (setq pos t mismatch t)))
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;; Move back the other way and verify we get back to the
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;; starting point. If not, these two parens don't really match.
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;; Maybe the one at point is escaped and doesn't really count,
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;; or one is inside a comment.
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(when (integerp pos)
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(unless (condition-case ()
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(eq outside (scan-sexps pos (- dir)))
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(error nil))
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(setq pos nil)))
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;; If found a "matching" paren, see if it is the right
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;; kind of paren to match the one we started at.
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(if (not (integerp pos))
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(if mismatch (list here-beg here-end nil nil t))
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(let ((beg (min pos outside)) (end (max pos outside)))
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(unless (eq (syntax-class (syntax-after beg)) 8)
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(setq mismatch
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(not (or (eq (char-before end)
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;; This can give nil.
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(cdr (syntax-after beg)))
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(eq (char-after beg)
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;; This can give nil.
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(cdr (syntax-after (1- end))))
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;; The cdr might hold a new paren-class
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;; info rather than a matching-char info,
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;; in which case the two CDRs should match.
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(eq (cdr (syntax-after (1- end)))
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(cdr (syntax-after beg)))))))
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(list here-beg here-end
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(if (= dir 1) (1- pos) pos)
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(if (= dir 1) pos (1+ pos))
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mismatch)))))))
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(defun show-paren-function ()
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"Highlight the parentheses until the next input arrives."
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(let ((data (and show-paren-mode (funcall show-paren-data-function))))
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(if (not data)
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(progn
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;; If show-paren-mode is nil in this buffer or if not at a paren that
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;; has a match, turn off any previous paren highlighting.
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(delete-overlay show-paren--overlay)
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(delete-overlay show-paren--overlay-1))
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;; Found something to highlight.
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(let* ((here-beg (nth 0 data))
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(here-end (nth 1 data))
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(there-beg (nth 2 data))
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(there-end (nth 3 data))
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(mismatch (nth 4 data))
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(highlight-expression
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(or (eq show-paren-style 'expression)
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(and there-beg
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(eq show-paren-style 'mixed)
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(let ((closest (if (< there-beg here-beg)
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(1- there-end) (1+ there-beg))))
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(not (pos-visible-in-window-p closest))))))
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(face
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(cond
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(mismatch
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(if show-paren-ring-bell-on-mismatch
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(beep))
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'show-paren-mismatch)
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(highlight-expression 'show-paren-match-expression)
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(t 'show-paren-match))))
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;;
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;; If matching backwards, highlight the closeparen
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;; before point as well as its matching open.
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;; If matching forward, and the openparen is unbalanced,
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;; highlight the paren at point to indicate misbalance.
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;; Otherwise, turn off any such highlighting.
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(if (or (not here-beg)
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(and (not show-paren-highlight-openparen)
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(> here-end (point))
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(<= here-beg (point))
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(integerp there-beg)))
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(delete-overlay show-paren--overlay-1)
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(move-overlay show-paren--overlay-1
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here-beg here-end (current-buffer))
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;; Always set the overlay face, since it varies.
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(overlay-put show-paren--overlay-1 'priority show-paren-priority)
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(overlay-put show-paren--overlay-1 'face face))
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;;
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;; Turn on highlighting for the matching paren, if found.
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;; If it's an unmatched paren, turn off any such highlighting.
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(if (not there-beg)
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(delete-overlay show-paren--overlay)
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(if highlight-expression
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(move-overlay show-paren--overlay
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(if (< there-beg here-beg) here-end here-beg)
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(if (< there-beg here-beg) there-beg there-end)
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(current-buffer))
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(move-overlay show-paren--overlay
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there-beg there-end (current-buffer)))
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;; Always set the overlay face, since it varies.
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(overlay-put show-paren--overlay 'priority show-paren-priority)
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(overlay-put show-paren--overlay 'face face))))))
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(provide 'paren)
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;;; paren.el ends here
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