lisp/textmodes/page.el

   1 ;;; page.el --- page motion commands for Emacs
   2
   3 ;; Copyright (C) 1985, 2001, 2002, 2003, 2004, 2005,
   4 ;;   2006, 2007 Free Software Foundation, Inc.
   5
   6 ;; Maintainer: FSF
   7 ;; Keywords: wp convenience
   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 ;; This code provides the page-oriented movement and selection commands
  29 ;; documented in the Emacs manual.
  30
  31 ;;; Code:
  32
  33 (defun forward-page (&optional count)
  34   "Move forward to page boundary.  With arg, repeat, or go back if negative.
  35 A page boundary is any line whose beginning matches the regexp
  36 `page-delimiter'."
  37   (interactive "p")
  38   (or count (setq count 1))
  39   (while (and (> count 0) (not (eobp)))
  40     ;; In case the page-delimiter matches the null string,
  41     ;; don't find a match without moving.
  42     (if (bolp) (forward-char 1))
  43     (if (re-search-forward page-delimiter nil t)
  44         nil
  45       (goto-char (point-max)))
  46     (setq count (1- count)))
  47   (while (and (< count 0) (not (bobp)))
  48     ;; In case the page-delimiter matches the null string,
  49     ;; don't find a match without moving.
  50     (and (save-excursion (re-search-backward page-delimiter nil t))
  51          (= (match-end 0) (point))
  52          (goto-char (match-beginning 0)))
  53     (forward-char -1)
  54     (if (re-search-backward page-delimiter nil t)
  55         ;; We found one--move to the end of it.
  56         (goto-char (match-end 0))
  57       ;; We found nothing--go to beg of buffer.
  58       (goto-char (point-min)))
  59     (setq count (1+ count))))
  60
  61 (defun backward-page (&optional count)
  62   "Move backward to page boundary.  With arg, repeat, or go fwd if negative.
  63 A page boundary is any line whose beginning matches the regexp
  64 `page-delimiter'."
  65   (interactive "p")
  66   (or count (setq count 1))
  67   (forward-page (- count)))
  68
  69 (defun mark-page (&optional arg)
  70   "Put mark at end of page, point at beginning.
  71 A numeric arg specifies to move forward or backward by that many pages,
  72 thus marking a page other than the one point was originally in."
  73   (interactive "P")
  74   (setq arg (if arg (prefix-numeric-value arg) 0))
  75   (if (> arg 0)
  76       (forward-page arg)
  77     (if (< arg 0)
  78         (forward-page (1- arg))))
  79   (forward-page)
  80   (push-mark nil t t)
  81   (forward-page -1))
  82
  83 (defun narrow-to-page (&optional arg)
  84   "Make text outside current page invisible.
  85 A numeric arg specifies to move forward or backward by that many pages,
  86 thus showing a page other than the one point was originally in."
  87   (interactive "P")
  88   (setq arg (if arg (prefix-numeric-value arg) 0))
  89   (save-excursion
  90     (widen)
  91     (if (> arg 0)
  92         (forward-page arg)
  93       (if (< arg 0)
  94           (let ((adjust 0)
  95                 (opoint (point)))
  96             ;; If we are not now at the beginning of a page,
  97             ;; move back one extra time, to get to the start of this page.
  98             (save-excursion
  99               (beginning-of-line)
 100               (or (and (looking-at page-delimiter)
 101                        (eq (match-end 0) opoint))
 102                   (setq adjust 1)))
 103             (forward-page (- arg adjust)))))
 104     ;; Find the end of the page.
 105     (set-match-data nil)
 106     (forward-page)
 107     ;; If we stopped due to end of buffer, stay there.
 108     ;; If we stopped after a page delimiter, put end of restriction
 109     ;; at the beginning of that line.
 110     ;; Before checking the match that was found,
 111     ;; verify that forward-page actually set the match data.
 112     (if (and (match-beginning 0)
 113              (save-excursion
 114                (goto-char (match-beginning 0)) ; was (beginning-of-line)
 115                (looking-at page-delimiter)))
 116         (goto-char (match-beginning 0))) ; was (beginning-of-line)
 117     (narrow-to-region (point)
 118                       (progn
 119                         ;; Find the top of the page.
 120                         (forward-page -1)
 121                         ;; If we found beginning of buffer, stay there.
 122                         ;; If extra text follows page delimiter on same line,
 123                         ;; include it.
 124                         ;; Otherwise, show text starting with following line.
 125                         (if (and (eolp) (not (bobp)))
 126                             (forward-line 1))
 127                         (point)))))
 128 (put 'narrow-to-page 'disabled t)
 129
 130 (defun count-lines-page ()
 131   "Report number of lines on current page, and how many are before or after point."
 132   (interactive)
 133   (save-excursion
 134     (let ((opoint (point)) beg end
 135           total before after)
 136       (forward-page)
 137       (beginning-of-line)
 138       (or (looking-at page-delimiter)
 139           (end-of-line))
 140       (setq end (point))
 141       (backward-page)
 142       (setq beg (point))
 143       (setq total (count-lines beg end)
 144             before (count-lines beg opoint)
 145             after (count-lines opoint end))
 146       (message "Page has %d lines (%d + %d)" total before after))))
 147
 148 (defun what-page ()
 149   "Print page and line number of point."
 150   (interactive)
 151   (save-restriction
 152     (widen)
 153     (save-excursion
 154       (beginning-of-line)
 155       (let ((count 1)
 156             (opoint (point)))
 157         (goto-char 1)
 158         (while (re-search-forward page-delimiter opoint t)
 159           (setq count (1+ count)))
 160         (message "Page %d, line %d"
 161                  count
 162                  (1+ (count-lines (point) opoint)))))))
 163 \f
 164 ;;; Place `provide' at end of file.
 165 (provide 'page)
 166
 167 ;;; arch-tag: e8d7a0bd-8655-4b6e-b852-f2ee25316a1d
 168 ;;; page.el ends here