lisp/reveal.el

   1 ;;; reveal.el --- Automatically reveal hidden text at point
   2
   3 ;; Copyright (C) 2000, 2001, 2004  Free Software Foundation, Inc.
   4
   5 ;; Author: Stefan Monnier <monnier@cs.yale.edu>
   6 ;; Keywords: outlines
   7
   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, Inc., 59 Temple Place - Suite 330,
  23 ;; Boston, MA 02111-1307, USA.
  24
  25 ;;; Commentary:
  26
  27 ;; Reveal mode is a minor mode that makes sure that text around point
  28 ;; is always visible.  When point enters a region of hidden text,
  29 ;; `reveal-mode' temporarily makes it visible.
  30 ;;
  31 ;; This is normally used in conjunction with `outline-minor-mode',
  32 ;; `hs-minor-mode', `hide-ifdef-mode', ...
  33 ;;
  34 ;; It only works with packages that hide text using overlays.
  35 ;; Packages can provide special support for it by placing
  36 ;; a function in the `reveal-toggle-invisible' property on the symbol
  37 ;; used as the value of the `invisible' overlay property.
  38 ;; The function is called right after revealing (or re-hiding) the
  39 ;; text with two arguments: the overlay and a boolean that's non-nil
  40 ;; if we have just revealed the text.  When revealing, that function
  41 ;; may re-hide some of the text.
  42
  43 ;;; Todo:
  44
  45 ;; - find other hysteresis features.
  46
  47 ;;; Code:
  48
  49 (require 'pcvs-util)
  50
  51 (defgroup reveal nil
  52   "Reveal hidden text on the fly."
  53   :group 'editing)
  54
  55 (defcustom reveal-around-mark t
  56   "Reveal text around the mark, if active."
  57   :type 'boolean)
  58
  59 (defvar reveal-open-spots nil)
  60 (make-variable-buffer-local 'reveal-open-spots)
  61
  62 (defvar reveal-last-tick nil)
  63 (make-variable-buffer-local 'reveal-last-tick)
  64
  65 ;; Actual code
  66
  67 (defun reveal-post-command ()
  68   ;; Refresh the spots that might have changed.
  69   ;; `Refreshing' here means to try and re-hide the corresponding text.
  70   ;; We don't refresh everything correctly:
  71   ;; - we only refresh spots in the current window.
  72   ;; FIXME: do we actually know that (current-buffer) = (window-buffer) ?
  73   (with-local-quit
  74   (condition-case err
  75    (let* ((spots (cvs-partition
  76                   (lambda (x)
  77                     ;; We refresh any spot in the current window as well
  78                     ;; as any spots associated with a dead window or a window
  79                     ;; which does not show this buffer any more.
  80                     (or (eq (car x) (selected-window))
  81                         (not (window-live-p (car x)))
  82                         (not (eq (window-buffer (car x))
  83                                  (current-buffer)))))
  84                   reveal-open-spots))
  85           (old-ols (mapcar 'cdr (car spots)))
  86           (repeat t))
  87      (setq reveal-open-spots (cdr spots))
  88      ;; Open new overlays.
  89      (while repeat
  90        (setq repeat nil)
  91        (dolist (ol (nconc (when (and reveal-around-mark mark-active)
  92                             (overlays-at (mark)))
  93                           (overlays-at (point))))
  94          (push (cons (selected-window) ol) reveal-open-spots)
  95          (setq old-ols (delq ol old-ols))
  96          (let ((open (overlay-get ol 'reveal-toggle-invisible)) inv)
  97            (when (or open
  98                      (and (setq inv (overlay-get ol 'invisible))
  99                           (symbolp inv)
 100                           (or (setq open (or (get inv 'reveal-toggle-invisible)
 101                                              (overlay-get ol 'isearch-open-invisible-temporary)))
 102                               (overlay-get ol 'isearch-open-invisible)
 103                               (and (consp buffer-invisibility-spec)
 104                                    (assq inv buffer-invisibility-spec)))
 105                           (overlay-put ol 'reveal-invisible inv)))
 106              (if (null open)
 107                  (overlay-put ol 'invisible nil)
 108                ;; Use the provided opening function and repeat (since the
 109                ;; opening function might have hidden a subpart around point).
 110                (setq repeat t)
 111                (condition-case err
 112                    (funcall open ol nil)
 113                  (error (message "!!Reveal-show: %s !!" err)
 114                         ;; Let's default to a meaningful behavior to avoid
 115                         ;; getting stuck in an infinite loop.
 116                         (setq repeat nil)
 117                         (overlay-put ol 'invisible nil))))))))
 118      ;; Close old overlays.
 119      (if (not (eq reveal-last-tick
 120                   (setq reveal-last-tick (buffer-modified-tick))))
 121          ;; The buffer was modified since last command: let's refrain from
 122          ;; closing any overlay because it tends to behave poorly when
 123          ;; inserting text at the end of an overlay (basically the overlay
 124          ;; should be rear-advance when it's open, but things like
 125          ;; outline-minor-mode make it non-rear-advance because it's
 126          ;; a better choice when it's closed).
 127          (dolist (ol old-ols)
 128            (push (cons (selected-window) ol) reveal-open-spots))
 129        ;; The last command was only a point motion or some such
 130        ;; non-buffer-modifying command.  Let's close whatever can be closed.
 131        (dolist (ol old-ols)
 132          (when (and (eq (current-buffer) (overlay-buffer ol))
 133                     (not (rassq ol reveal-open-spots)))
 134            (if (and (>= (point) (save-excursion
 135                                   (goto-char (overlay-start ol))
 136                                   (line-beginning-position 1)))
 137                     (<= (point) (save-excursion
 138                                   (goto-char (overlay-end ol))
 139                                   (line-beginning-position 2))))
 140                ;; Still near the overlay: keep it open.
 141                (push (cons (selected-window) ol) reveal-open-spots)
 142              ;; Really close it.
 143              (let ((open (overlay-get ol 'reveal-toggle-invisible)) inv)
 144                (if (or open
 145                        (and (setq inv (overlay-get ol 'reveal-invisible))
 146                             (setq open (or (get inv 'reveal-toggle-invisible)
 147                                            (overlay-get ol 'isearch-open-invisible-temporary)))))
 148                    (condition-case err
 149                        (funcall open ol t)
 150                      (error (message "!!Reveal-hide: %s !!" err)))
 151                  (overlay-put ol 'invisible inv))))))))
 152    (error (message "Reveal: %s" err)))))
 153
 154 ;;;###autoload
 155 (define-minor-mode reveal-mode
 156   "Toggle Reveal mode on or off.
 157 Reveal mode renders invisible text around point visible again.
 158
 159 Interactively, with no prefix argument, toggle the mode.
 160 With universal prefix ARG (or if ARG is nil) turn mode on.
 161 With zero or negative ARG turn mode off."
 162   :lighter (global-reveal-mode nil " Reveal")
 163   (if reveal-mode
 164       (progn
 165         (set (make-local-variable 'search-invisible) t)
 166         (add-hook 'post-command-hook 'reveal-post-command nil t))
 167     (kill-local-variable 'search-invisible)
 168     (remove-hook 'post-command-hook 'reveal-post-command t)))
 169
 170 ;;;###autoload
 171 (define-minor-mode global-reveal-mode
 172   "Toggle Reveal mode in all buffers on or off.
 173 Reveal mode renders invisible text around point visible again.
 174
 175 Interactively, with no prefix argument, toggle the mode.
 176 With universal prefix ARG (or if ARG is nil) turn mode on.
 177 With zero or negative ARG turn mode off."
 178   :global t :group 'reveal
 179   (setq-default reveal-mode global-reveal-mode)
 180   (if global-reveal-mode
 181       (progn
 182         (setq search-invisible t)
 183         (add-hook 'post-command-hook 'reveal-post-command))
 184     (setq search-invisible 'open)       ;FIXME
 185     (remove-hook 'post-command-hook 'reveal-post-command)))
 186
 187 (provide 'reveal)
 188
 189 ;; arch-tag: 96ba0242-2274-4ed7-8e10-26bc0707b4d8
 190 ;;; reveal.el ends here