249 lines
10 KiB
EmacsLisp
249 lines
10 KiB
EmacsLisp
;;; reveal.el --- Automatically reveal hidden text at point -*- lexical-binding: t -*-
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;; Copyright (C) 2000-2024 Free Software Foundation, Inc.
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;; Author: Stefan Monnier <monnier@iro.umontreal.ca>
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;; Keywords: outlines
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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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;; Reveal mode is a minor mode that makes sure that text around point
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;; is always visible. When point enters a region of hidden text,
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;; `reveal-mode' temporarily makes it visible.
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;;
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;; Overlays can also use the `display' property. For them to be
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;; revealed, the `reveal-toggle-invisible' property also has to be
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;; present, and should be a function to toggle between having a
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;; display property and not.
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;;
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;; This is normally used in conjunction with `outline-minor-mode',
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;; `hs-minor-mode', `hide-ifdef-mode', ...
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;;
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;; It only works with packages that hide text using overlays.
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;; Packages can provide special support for it by placing
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;; a function in the `reveal-toggle-invisible' property on the symbol
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;; used as the value of the `invisible' overlay property.
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;; The function is called right after revealing (or re-hiding) the
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;; text with two arguments: the overlay and a boolean that's non-nil
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;; if we have just revealed the text. When revealing, that function
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;; may re-hide some of the text.
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;;; Todo:
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;; - find other hysteresis features.
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;; - don't hide after a scroll command
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;; - delay hiding by a couple seconds (i.e. hide in the background)
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;;; Code:
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(defgroup reveal nil
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"Reveal hidden text on the fly."
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:group 'convenience)
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(defcustom reveal-around-mark t
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"Reveal text around the mark, if active."
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:type 'boolean
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:group 'reveal)
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(defcustom reveal-auto-hide t
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"Automatically hide revealed text when leaving it.
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If nil, the `reveal-hide-revealed' command can be useful to hide
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revealed text manually."
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:type 'boolean
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:version "28.1")
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(defvar-local reveal-open-spots nil
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"List of spots in the buffer which are open.
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Each element has the form (WINDOW . OVERLAY).")
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(defvar-local reveal-last-tick nil)
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;; Actual code
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(defun reveal-post-command ()
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;; Refresh the spots that might have changed.
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;; `Refreshing' here means to try and re-hide the corresponding text.
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;; We don't refresh everything correctly:
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;; - we only refresh spots in the current window.
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;; FIXME: do we actually know that (current-buffer) = (window-buffer) ?
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(with-local-quit
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(with-demoted-errors "Reveal: %s"
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(let ((old-ols
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(delq nil
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(mapcar
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(lambda (x)
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;; We refresh any spot in the current window as well
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;; as any spots associated with a dead window or
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;; a window which does not show this buffer any more.
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(cond
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((eq (car x) (selected-window)) (cdr x))
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((not (and (window-live-p (car x))
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(eq (window-buffer (car x))
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(current-buffer))))
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;; Adopt this since it's owned by a window that's
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;; either not live or at least not showing this
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;; buffer any more.
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(setcar x (selected-window))
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(cdr x))))
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reveal-open-spots))))
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(setq old-ols (reveal-open-new-overlays old-ols))
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(when reveal-auto-hide
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(reveal-close-old-overlays old-ols))))))
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(defun reveal-open-new-overlays (old-ols)
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(let ((repeat t))
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(while repeat
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(setq repeat nil)
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(dolist (ol (nconc (when (and reveal-around-mark mark-active)
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(overlays-at (mark)))
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(overlays-at (point))))
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(setq old-ols (delq ol old-ols))
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(when (overlay-start ol) ;Check it's still live.
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;; We either have an invisible overlay, or a display
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;; overlay. Always reveal invisible text, but only reveal
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;; display properties if `reveal-toggle-invisible' is
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;; present.
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(let* ((inv (overlay-get ol 'invisible))
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(disp (and (overlay-get ol 'display)
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(overlay-get ol 'reveal-toggle-invisible)))
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(hidden (invisible-p inv))
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(ellipsis (and hidden (not (eq t hidden))))
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open)
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(when (and (or ellipsis disp)
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(or (setq open
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(or (overlay-get ol 'reveal-toggle-invisible)
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(and (symbolp inv)
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(get inv 'reveal-toggle-invisible))
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(overlay-get
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ol 'isearch-open-invisible-temporary)))
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(overlay-get ol 'isearch-open-invisible)
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(and (consp buffer-invisibility-spec)
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(cdr (assq inv buffer-invisibility-spec)))))
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(when inv
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(overlay-put ol 'reveal-invisible inv))
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(push (cons (selected-window) ol) reveal-open-spots)
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(if (null open)
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(overlay-put ol 'invisible nil)
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;; Use the provided opening function and repeat (since the
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;; opening function might have hidden a subpart around point
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;; or moved/killed some of the overlays).
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(setq repeat t)
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(condition-case err
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(funcall open ol nil)
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(error (message "!!Reveal-show (funcall %s %s nil): %s !!"
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open ol err)
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;; Let's default to a meaningful behavior to avoid
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;; getting stuck in an infinite loop.
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(setq repeat nil)
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(overlay-put ol 'invisible nil))))))))))
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old-ols)
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(defun reveal-close-old-overlays (old-ols)
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(if (or track-mouse ;Don't close in the middle of a click.
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(not (eq reveal-last-tick
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(setq reveal-last-tick (buffer-modified-tick)))))
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;; The buffer was modified since last command: let's refrain from
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;; closing any overlay because it tends to behave poorly when
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;; inserting text at the end of an overlay (basically the overlay
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;; should be rear-advance when it's open, but things like
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;; outline-minor-mode make it non-rear-advance because it's
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;; a better choice when it's closed).
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nil
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;; The last command was only a point motion or some such
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;; non-buffer-modifying command. Let's close whatever can be closed.
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(dolist (ol old-ols)
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(if (and (overlay-start ol) ;Check it's still live.
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(>= (point) (save-excursion
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(goto-char (overlay-start ol))
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(line-beginning-position 1)))
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(<= (point) (save-excursion
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(goto-char (overlay-end ol))
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(line-beginning-position 2)))
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;; If the application has moved the overlay to some other
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;; buffer, we'd better reset the buffer to its
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;; original state.
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(eq (current-buffer) (overlay-buffer ol)))
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;; Still near the overlay: keep it open.
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nil
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;; Really close it.
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(let* ((inv (overlay-get ol 'reveal-invisible))
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(open (or (overlay-get ol 'reveal-toggle-invisible)
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(get inv 'reveal-toggle-invisible)
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(overlay-get ol 'isearch-open-invisible-temporary))))
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(if (and (overlay-start ol) ;Check it's still live.
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open)
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(condition-case err
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(funcall open ol t)
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(error (message "!!Reveal-hide (funcall %s %s t): %s !!"
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open ol err)))
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(overlay-put ol 'invisible inv))
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;; Remove the overlay from the list of open spots.
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(overlay-put ol 'reveal-invisible nil)
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(setq reveal-open-spots
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(delq (rassoc ol reveal-open-spots)
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reveal-open-spots)))))))
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(defun reveal-hide-revealed ()
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"Hide all revealed text.
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If there is revealed text under point, this command does not hide
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that text."
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(interactive)
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(let ((reveal-auto-hide t))
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(reveal-post-command)))
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(defvar-keymap reveal-mode-map
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;; Override the default move-beginning-of-line and move-end-of-line
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;; which skips valuable invisible text.
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"<remap> <move-beginning-of-line>" #'beginning-of-line
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"<remap> <move-end-of-line>" #'end-of-line)
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;;;###autoload
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(define-minor-mode reveal-mode
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"Toggle uncloaking of invisible text near point (Reveal mode).
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Reveal mode is a buffer-local minor mode. When enabled, it
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reveals invisible text around point.
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Also see the `reveal-auto-hide' variable."
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:group 'reveal
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:lighter (global-reveal-mode nil " Reveal")
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:keymap reveal-mode-map
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(if reveal-mode
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(progn
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(setq-local search-invisible t)
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(add-hook 'post-command-hook 'reveal-post-command nil t))
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(kill-local-variable 'search-invisible)
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(remove-hook 'post-command-hook 'reveal-post-command t)))
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;;;###autoload
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(define-minor-mode global-reveal-mode
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"Toggle Reveal mode in all buffers (Global Reveal mode).
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Reveal mode renders invisible text around point visible again."
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:global t :group 'reveal
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(setq-default reveal-mode global-reveal-mode)
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(if global-reveal-mode
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(progn
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(setq search-invisible t)
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(add-hook 'post-command-hook 'reveal-post-command))
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(setq search-invisible 'open) ;FIXME
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(remove-hook 'post-command-hook 'reveal-post-command)))
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(provide 'reveal)
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;;; reveal.el ends here
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