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[emacs.git] / lisp / textmodes / page.el
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1 ;;; page.el --- page motion commands for Emacs
3 ;; Copyright (C) 1985, 2001-2014 Free Software Foundation, Inc.
5 ;; Maintainer: emacs-devel@gnu.org
6 ;; Keywords: wp convenience
7 ;; Package: emacs
9 ;; This file is part of GNU Emacs.
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 3 of the License, or
14 ;; (at your option) any later version.
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.
21 ;; You should have received a copy of the GNU General Public License
22 ;; along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>.
24 ;;; Commentary:
26 ;; This code provides the page-oriented movement and selection commands
27 ;; documented in the Emacs manual.
29 ;;; Code:
31 (defun forward-page (&optional count)
32 "Move forward to page boundary. With arg, repeat, or go back if negative.
33 A page boundary is any line whose beginning matches the regexp
34 `page-delimiter'."
35 (interactive "p")
36 (or count (setq count 1))
37 (while (and (> count 0) (not (eobp)))
38 ;; In case the page-delimiter matches the null string,
39 ;; don't find a match without moving.
40 (if (bolp) (forward-char 1))
41 (if (re-search-forward page-delimiter nil t)
42 nil
43 (goto-char (point-max)))
44 (setq count (1- count)))
45 (while (and (< count 0) (not (bobp)))
46 ;; In case the page-delimiter matches the null string,
47 ;; don't find a match without moving.
48 (and (save-excursion (re-search-backward page-delimiter nil t))
49 (= (match-end 0) (point))
50 (goto-char (match-beginning 0)))
51 (forward-char -1)
52 (if (re-search-backward page-delimiter nil t)
53 ;; We found one--move to the end of it.
54 (goto-char (match-end 0))
55 ;; We found nothing--go to beg of buffer.
56 (goto-char (point-min)))
57 (setq count (1+ count))))
59 (defun backward-page (&optional count)
60 "Move backward to page boundary. With arg, repeat, or go fwd if negative.
61 A page boundary is any line whose beginning matches the regexp
62 `page-delimiter'."
63 (interactive "p")
64 (or count (setq count 1))
65 (forward-page (- count)))
67 (defun mark-page (&optional arg)
68 "Put mark at end of page, point at beginning.
69 A numeric arg specifies to move forward or backward by that many pages,
70 thus marking a page other than the one point was originally in."
71 (interactive "P")
72 (setq arg (if arg (prefix-numeric-value arg) 0))
73 (if (> arg 0)
74 (forward-page arg)
75 (if (< arg 0)
76 (forward-page (1- arg))))
77 (forward-page)
78 (push-mark nil t t)
79 (forward-page -1))
81 (defun narrow-to-page (&optional arg)
82 "Make text outside current page invisible.
83 A numeric arg specifies to move forward or backward by that many pages,
84 thus showing a page other than the one point was originally in."
85 (interactive "P")
86 (setq arg (if arg (prefix-numeric-value arg) 0))
87 (save-excursion
88 (widen)
89 (if (> arg 0)
90 (forward-page arg)
91 (if (< arg 0)
92 (let ((adjust 0)
93 (opoint (point)))
94 ;; If we are not now at the beginning of a page,
95 ;; move back one extra time, to get to the start of this page.
96 (save-excursion
97 (beginning-of-line)
98 (or (and (looking-at page-delimiter)
99 (eq (match-end 0) opoint))
100 (setq adjust 1)))
101 (forward-page (- arg adjust)))))
102 ;; Find the end of the page.
103 (set-match-data nil)
104 (forward-page)
105 ;; If we stopped due to end of buffer, stay there.
106 ;; If we stopped after a page delimiter, put end of restriction
107 ;; at the beginning of that line.
108 ;; Before checking the match that was found,
109 ;; verify that forward-page actually set the match data.
110 (if (and (match-beginning 0)
111 (save-excursion
112 (goto-char (match-beginning 0)) ; was (beginning-of-line)
113 (looking-at page-delimiter)))
114 (goto-char (match-beginning 0))) ; was (beginning-of-line)
115 (narrow-to-region (point)
116 (progn
117 ;; Find the top of the page.
118 (forward-page -1)
119 ;; If we found beginning of buffer, stay there.
120 ;; If extra text follows page delimiter on same line,
121 ;; include it.
122 ;; Otherwise, show text starting with following line.
123 (if (and (eolp) (not (bobp)))
124 (forward-line 1))
125 (point)))))
126 (put 'narrow-to-page 'disabled t)
128 (defun count-lines-page ()
129 "Report number of lines on current page, and how many are before or after point."
130 (interactive)
131 (save-excursion
132 (let ((opoint (point)) beg end
133 total before after)
134 (forward-page)
135 (beginning-of-line)
136 (or (looking-at page-delimiter)
137 (end-of-line))
138 (setq end (point))
139 (backward-page)
140 (setq beg (point))
141 (setq total (count-lines beg end)
142 before (count-lines beg opoint)
143 after (count-lines opoint end))
144 (message "Page has %d lines (%d + %d)" total before after))))
146 (defun what-page ()
147 "Print page and line number of point."
148 (interactive)
149 (save-restriction
150 (widen)
151 (save-excursion
152 (let ((count 1)
153 (opoint (point)))
154 (goto-char (point-min))
155 (while (re-search-forward page-delimiter opoint t)
156 (if (= (match-beginning 0) (match-end 0))
157 (forward-char 1))
158 (setq count (1+ count)))
159 (message "Page %d, line %d" count (line-number-at-pos opoint))))))
163 ;;; Place `provide' at end of file.
164 (provide 'page)
166 ;;; page.el ends here