lisp/elide-head.el

   1 ;;; elide-head.el --- hide headers in files
   2
   3 ;; Copyright (C) 1999, 2001, 2002, 2003, 2004, 2005,
   4 ;;   2006, 2007 Free Software Foundation, Inc.
   5
   6 ;; Author: Dave Love <fx@gnu.org>
   7 ;; Keywords: outlines tools
   8
   9 ;; This file is part of GNU Emacs.
  10
  11 ;; GNU Emacs is free software; you can redistribute it and/or modify
  12 ;; it under the terms of the GNU General Public License as published by
  13 ;; the Free Software Foundation; either version 2, or (at your option)
  14 ;; any later version.
  15
  16 ;; GNU Emacs is distributed in the hope that it will be useful,
  17 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  18 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19 ;; GNU General Public License for more details.
  20
  21 ;; You should have received a copy of the GNU General Public License
  22 ;; along with GNU Emacs; see the file COPYING.  If not, write to the
  23 ;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  24 ;; Boston, MA 02110-1301, USA.
  25
  26 ;;; Commentary:
  27
  28 ;; Functionality for eliding boilerplate text (normally copyright
  29 ;; notices) in file headers to avoid clutter when you know what it
  30 ;; says.
  31 ;;
  32 ;; `elide-head-headers-to-hide' controls what is elided by the command
  33 ;; `elide-head'.  A buffer-local invisible overlay manages the
  34 ;; elision.
  35
  36 ;; You might add `elide-head' to appropriate major mode hooks or to
  37 ;; `find-file-hook'.  Please do not do this in site init files.  If
  38 ;; you do, information may be hidden from users who don't know it
  39 ;; already.
  40
  41 ;; Note that `hs-minor-mode' will do a similar job by default, but
  42 ;; it's not selective about what leading commentary it hides.
  43
  44 ;; Inspired by jwz's hide-copyleft.el, for which we don't have an
  45 ;; assignment.
  46
  47 ;;; Code:
  48
  49 (defgroup elide-head nil
  50   "Eliding copyright headers and the like in source files."
  51   :version "21.1"
  52   :prefix "elide-head"
  53   :group 'tools)
  54
  55 (defcustom elide-head-headers-to-hide
  56   '(("is free software; you can redistribute it" . ; GNU boilerplate
  57      "Boston, MA 0211\\(1-1307\\|0-1301\\), USA\\.")
  58     ("The Regents of the University of California\\.  All rights reserved\\." .
  59      "SUCH DAMAGE\\.")                                ; BSD
  60     ("Permission is hereby granted, free of charge" . ; X11
  61      "authorization from the X Consortium\\."))
  62   "Alist of regexps defining start end end of text to elide.
  63
  64 The cars of elements of the list are searched for in order.  Text is
  65 elided with an invisible overlay from the end of the line where the
  66 first match is found to the end of the match for the corresponding
  67 cdr."
  68   :group 'elide-head
  69   :type '(alist :key-type  (string :tag "Start regexp")
  70                 :value-type (string :tag "End regexp")))
  71
  72 (defvar elide-head-overlay nil)
  73 (make-variable-buffer-local 'elide-head-overlay)
  74
  75 ;;;###autoload
  76 (defun elide-head (&optional arg)
  77   "Hide header material in buffer according to `elide-head-headers-to-hide'.
  78
  79 The header is made invisible with an overlay.  With a prefix arg, show
  80 an elided material again.
  81
  82 This is suitable as an entry on `find-file-hook' or appropriate mode hooks."
  83   (interactive "P")
  84   (if arg
  85       (elide-head-show)
  86     (save-excursion
  87       (save-restriction
  88         (let ((rest elide-head-headers-to-hide)
  89               beg end)
  90           (widen)
  91           (goto-char (point-min))
  92           (while rest
  93             (save-excursion
  94               (when (re-search-forward (caar rest) nil t)
  95                 (setq beg (point))
  96                 (when (re-search-forward (cdar rest) nil t)
  97                   (setq end (point-marker)
  98                         rest nil))))
  99             (if rest (setq rest (cdr rest))))
 100           (if (not (and beg end))
 101               (if (interactive-p)
 102                   (message "No header found"))
 103             (goto-char beg)
 104             (end-of-line)
 105             (if (overlayp elide-head-overlay)
 106                 (move-overlay elide-head-overlay (point-marker) end)
 107               (setq elide-head-overlay (make-overlay (point-marker) end)))
 108             (overlay-put elide-head-overlay 'invisible t)
 109             (overlay-put elide-head-overlay 'evaporate t)
 110             (overlay-put elide-head-overlay 'after-string "...")))))))
 111
 112 (defun elide-head-show ()
 113   "Show a header elided current buffer by \\[elide-head]."
 114   (interactive)
 115   (if (and (overlayp elide-head-overlay)
 116            (overlay-buffer elide-head-overlay))
 117       (delete-overlay elide-head-overlay)
 118     (if (interactive-p)
 119         (message "No header hidden"))))
 120
 121 (provide 'elide-head)
 122
 123 ;;; arch-tag: a00e6b5b-6aeb-45b1-b734-63e23df80928
 124 ;;; elide-head.el ends here