lisp/reveal.el

   1 ;;; reveal.el --- Automatically reveal hidden text at point
   2
   3 ;; Copyright (C) 2000, 2001  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 ;; This file 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 ;; This file 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 ;; Actual code
  63
  64 (defun reveal-post-command ()
  65   ;; Refresh the spots that might have changed.
  66   ;; `Refreshing' here means to try and re-hide the corresponding text.
  67   ;; We don't refresh everything correctly:
  68   ;; - we only refresh spots in the current window.
  69   ;; FIXME: do we actually know that (current-buffer) = (window-buffer) ?
  70   (with-local-quit
  71    (let* ((spots (cvs-partition
  72                   (lambda (x)
  73                     ;; We refresh any spot in the current window as well
  74                     ;; as any spots associated with a dead window or a window
  75                     ;; which does not show this buffer any more.
  76                     (or (eq (car x) (selected-window))
  77                         (not (window-live-p (car x)))
  78                         (not (eq (window-buffer (car x))
  79                                  (current-buffer)))))
  80                   reveal-open-spots))
  81           (old-ols (mapcar 'cdr (car spots)))
  82           (repeat t)
  83           ;; `post-command-hook' binds it to t, but the user might want to
  84           ;; interrupt our work if we somehow get stuck in an infinite loop.
  85           (inhibit-quit nil)
  86           inv open)
  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          (when (setq inv (overlay-get ol 'invisible))
  97            (when (or (overlay-get ol 'isearch-open-invisible)
  98                      (and (consp buffer-invisibility-spec)
  99                           (assq inv buffer-invisibility-spec)))
 100              (overlay-put ol 'reveal-invisible inv)
 101              (overlay-put ol 'invisible nil)
 102              (when (setq open (get inv 'reveal-toggle-invisible))
 103                ;; Use the provided opening function and repeat (since the
 104                ;; opening function might have hidden a subpart around point).
 105                (setq repeat t)
 106                (condition-case err
 107                    (funcall open ol t)
 108                  (error (message "!!Reveal-show: %s !!" err))))))))
 109      ;; Close old overlays.
 110      (dolist (ol old-ols)
 111        (when (and (setq inv (overlay-get ol 'reveal-invisible))
 112                   (eq (current-buffer) (overlay-buffer ol))
 113                   (not (rassq ol reveal-open-spots)))
 114          (if (and (>= (point) (save-excursion
 115                                 (goto-char (overlay-start ol))
 116                                 (line-beginning-position 1)))
 117                   (<= (point) (save-excursion
 118                                 (goto-char (overlay-end ol))
 119                                 (line-beginning-position 2))))
 120              ;; Still near the overlay: keep it open.
 121              (push (cons (selected-window) ol) reveal-open-spots)
 122            ;; Really close it.
 123            (overlay-put ol 'invisible inv)
 124            (when (setq open (get inv 'reveal-toggle-invisible))
 125              (condition-case err
 126                  (funcall open ol nil)
 127                (error (message "!!Reveal-hide: %s !!" err))))))))))
 128
 129 ;;;###autoload
 130 (define-minor-mode reveal-mode
 131   "Toggle Reveal mode on or off.
 132 Reveal mode renders invisible text around point visible again.
 133
 134 Interactively, with no prefix argument, toggle the mode.
 135 With universal prefix ARG (or if ARG is nil) turn mode on.
 136 With zero or negative ARG turn mode off."
 137   :lighter (global-reveal-mode nil " Reveal")
 138   (if reveal-mode
 139       (progn
 140         (set (make-local-variable 'search-invisible) t)
 141         (add-hook 'post-command-hook 'reveal-post-command nil t))
 142     (kill-local-variable 'search-invisible)
 143     (remove-hook 'post-command-hook 'reveal-post-command t)))
 144
 145 ;;;###autoload
 146 (define-minor-mode global-reveal-mode
 147   "Toggle Reveal mode in all buffers on or off.
 148 Reveal mode renders invisible text around point visible again.
 149
 150 Interactively, with no prefix argument, toggle the mode.
 151 With universal prefix ARG (or if ARG is nil) turn mode on.
 152 With zero or negative ARG turn mode off."
 153   :global t
 154   (setq-default reveal-mode global-reveal-mode)
 155   (if global-reveal-mode
 156       (progn
 157         (setq search-invisible t)
 158         (add-hook 'post-command-hook 'reveal-post-command))
 159     (setq search-invisible 'open)       ;FIXME
 160     (remove-hook 'post-command-hook 'reveal-post-command)))
 161
 162 (provide 'reveal)
 163 ;;; reveal.el ends here