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;;; simple.el --- basic editing commands for Emacs

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;; Copyright (C) 1985, 86, 87, 93, 94, 95, 96, 1997
;;        Free Software Foundation, Inc.
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;; This file is part of GNU Emacs.

;; GNU Emacs is free software; you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
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;; the Free Software Foundation; either version 2, or (at your option)
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;; any later version.

;; GNU Emacs is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;; GNU General Public License for more details.

;; You should have received a copy of the GNU General Public License
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;; along with GNU Emacs; see the file COPYING.  If not, write to the
;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
;; Boston, MA 02111-1307, USA.
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;;; Commentary:

;; A grab-bag of basic Emacs commands not specifically related to some
;; major mode or to file-handling.

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;;; Code:
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(defgroup killing nil
  "Killing and yanking commands"
  :group 'editing)

(defgroup fill-comments nil
  "Indenting and filling of comments."
  :prefix "comment-"
  :group 'fill)

(defgroup paren-matching nil
  "Highlight (un)matching of parens and expressions."
  :prefix "paren-"
  :prefix "blink-matching-"
  :group 'matching)


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(defun newline (&optional arg)
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  "Insert a newline, and move to left margin of the new line if it's blank.
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The newline is marked with the text-property `hard'.
With arg, insert that many newlines.
In Auto Fill mode, if no numeric arg, break the preceding line if it's long."
  (interactive "*P")
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  (barf-if-buffer-read-only)
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  ;; Inserting a newline at the end of a line produces better redisplay in
  ;; try_window_id than inserting at the beginning of a line, and the textual
  ;; result is the same.  So, if we're at beginning of line, pretend to be at
  ;; the end of the previous line.
  (let ((flag (and (not (bobp)) 
		   (bolp)
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		   ;; Make sure no functions want to be told about
		   ;; the range of the changes.
		   (not after-change-function)
		   (not before-change-function)
		   (not after-change-functions)
		   (not before-change-functions)
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		   ;; Make sure there are no markers here.
		   (not (buffer-has-markers-at (1- (point))))
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		   ;; Make sure no text properties want to know
		   ;; where the change was.
		   (not (get-char-property (1- (point)) 'modification-hooks))
		   (not (get-char-property (1- (point)) 'insert-behind-hooks))
		   (or (eobp)
		       (not (get-char-property (point) 'insert-in-front-hooks)))
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		   ;; Make sure the newline before point isn't intangible.
		   (not (get-char-property (1- (point)) 'intangible))
		   ;; Make sure the newline before point isn't read-only.
		   (not (get-char-property (1- (point)) 'read-only))
		   ;; Make sure the newline before point isn't invisible.
		   (not (get-char-property (1- (point)) 'invisible))
		   ;; Make sure the newline before point has the same
		   ;; properties as the char before it (if any).
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		   (< (or (previous-property-change (point)) -2) 
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		      (- (point) 2))))
	(was-page-start (and (bolp)
			     (looking-at page-delimiter)))
	(beforepos (point)))
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    (if flag (backward-char 1))
    ;; Call self-insert so that auto-fill, abbrev expansion etc. happens.
    ;; Set last-command-char to tell self-insert what to insert.
    (let ((last-command-char ?\n)
	  ;; Don't auto-fill if we have a numeric argument.
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	  ;; Also not if flag is true (it would fill wrong line);
	  ;; there is no need to since we're at BOL.
	  (auto-fill-function (if (or arg flag) nil auto-fill-function)))
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      (unwind-protect
	  (self-insert-command (prefix-numeric-value arg))
	;; If we get an error in self-insert-command, put point at right place.
	(if flag (forward-char 1))))
    ;; If we did *not* get an error, cancel that forward-char.
    (if flag (backward-char 1))
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    ;; Mark the newline(s) `hard'.
    (if use-hard-newlines
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	(set-hard-newline-properties 
	 (- (point) (if arg (prefix-numeric-value arg) 1)) (point)))
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    ;; If the newline leaves the previous line blank,
    ;; and we have a left margin, delete that from the blank line.
    (or flag
	(save-excursion
	  (goto-char beforepos)
	  (beginning-of-line)
	  (and (looking-at "[ \t]$")
	       (> (current-left-margin) 0)
	       (delete-region (point) (progn (end-of-line) (point))))))
    (if flag (forward-char 1))
    ;; Indent the line after the newline, except in one case:
    ;; when we added the newline at the beginning of a line
    ;; which starts a page.
    (or was-page-start
	(move-to-left-margin nil t)))
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  nil)

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(defun set-hard-newline-properties (from to)
  (let ((sticky (get-text-property from 'rear-nonsticky)))
    (put-text-property from to 'hard 't)
    ;; If rear-nonsticky is not "t", add 'hard to rear-nonsticky list
    (if (and (listp sticky) (not (memq 'hard sticky)))
	(put-text-property from (point) 'rear-nonsticky
			   (cons 'hard sticky)))))

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(defun open-line (arg)
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  "Insert a newline and leave point before it.
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If there is a fill prefix and/or a left-margin, insert them on the new line
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if the line would have been blank.
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With arg N, insert N newlines."
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  (interactive "*p")
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  (let* ((do-fill-prefix (and fill-prefix (bolp)))
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	 (do-left-margin (and (bolp) (> (current-left-margin) 0)))
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	 (loc (point)))
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    (newline arg)
    (goto-char loc)
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    (while (> arg 0)
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      (cond ((bolp)
	     (if do-left-margin (indent-to (current-left-margin)))
	     (if do-fill-prefix (insert-and-inherit fill-prefix))))
      (forward-line 1)
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      (setq arg (1- arg)))
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    (goto-char loc)
    (end-of-line)))
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(defun split-line ()
  "Split current line, moving portion beyond point vertically down."
  (interactive "*")
  (skip-chars-forward " \t")
  (let ((col (current-column))
	(pos (point)))
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    (newline 1)
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    (indent-to col 0)
    (goto-char pos)))

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(defvar quoted-insert-character-offset 2048
  "Offset added by \\[quoted-insert] to character codes 0200 and above.")

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(defun quoted-insert (arg)
  "Read next input character and insert it.
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This is useful for inserting control characters.
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You may also type up to 3 octal digits, to insert a character with that code.
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In overwrite mode, this function inserts the character anyway, and
does not handle octal digits specially.  This means that if you use
overwrite as your normal editing mode, you can use this function to
insert characters when necessary.

In binary overwrite mode, this function does overwrite, and octal
digits are interpreted as a character code.  This is supposed to make
this function useful in editing binary files."
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  (interactive "*p")
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  (let ((char (if (or (not overwrite-mode)
		      (eq overwrite-mode 'overwrite-mode-binary))
		  (read-quoted-char)
		(read-char))))
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    ;; Assume character codes 0200 - 0377 stand for 
    ;; European characters in Latin-1, and convert them
    ;; to Emacs characters.
    (and enable-multibyte-characters
	 (>= char ?\200)
	 (setq char (+ quoted-insert-character-offset char)))
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    (if (> arg 0)
	(if (eq overwrite-mode 'overwrite-mode-binary)
	    (delete-char arg)))
    (while (> arg 0)
      (insert-and-inherit char)
      (setq arg (1- arg)))))
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(defun delete-indentation (&optional arg)
  "Join this line to previous and fix up whitespace at join.
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If there is a fill prefix, delete it from the beginning of this line.
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With argument, join this line to following line."
  (interactive "*P")
  (beginning-of-line)
  (if arg (forward-line 1))
  (if (eq (preceding-char) ?\n)
      (progn
	(delete-region (point) (1- (point)))
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	;; If the second line started with the fill prefix,
	;; delete the prefix.
	(if (and fill-prefix
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		 (<= (+ (point) (length fill-prefix)) (point-max))
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		 (string= fill-prefix
			  (buffer-substring (point)
					    (+ (point) (length fill-prefix)))))
	    (delete-region (point) (+ (point) (length fill-prefix))))
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	(fixup-whitespace))))

(defun fixup-whitespace ()
  "Fixup white space between objects around point.
Leave one space or none, according to the context."
  (interactive "*")
  (save-excursion
    (delete-horizontal-space)
    (if (or (looking-at "^\\|\\s)")
	    (save-excursion (forward-char -1)
			    (looking-at "$\\|\\s(\\|\\s'")))
	nil
      (insert ?\ ))))

(defun delete-horizontal-space ()
  "Delete all spaces and tabs around point."
  (interactive "*")
  (skip-chars-backward " \t")
  (delete-region (point) (progn (skip-chars-forward " \t") (point))))

(defun just-one-space ()
  "Delete all spaces and tabs around point, leaving one space."
  (interactive "*")
  (skip-chars-backward " \t")
  (if (= (following-char) ? )
      (forward-char 1)
    (insert ? ))
  (delete-region (point) (progn (skip-chars-forward " \t") (point))))

(defun delete-blank-lines ()
  "On blank line, delete all surrounding blank lines, leaving just one.
On isolated blank line, delete that one.
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On nonblank line, delete any immediately following blank lines."
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  (interactive "*")
  (let (thisblank singleblank)
    (save-excursion
      (beginning-of-line)
      (setq thisblank (looking-at "[ \t]*$"))
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      ;; Set singleblank if there is just one blank line here.
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      (setq singleblank
	    (and thisblank
		 (not (looking-at "[ \t]*\n[ \t]*$"))
		 (or (bobp)
		     (progn (forward-line -1)
			    (not (looking-at "[ \t]*$")))))))
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    ;; Delete preceding blank lines, and this one too if it's the only one.
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    (if thisblank
	(progn
	  (beginning-of-line)
	  (if singleblank (forward-line 1))
	  (delete-region (point)
			 (if (re-search-backward "[^ \t\n]" nil t)
			     (progn (forward-line 1) (point))
			   (point-min)))))
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    ;; Delete following blank lines, unless the current line is blank
    ;; and there are no following blank lines.
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    (if (not (and thisblank singleblank))
	(save-excursion
	  (end-of-line)
	  (forward-line 1)
	  (delete-region (point)
			 (if (re-search-forward "[^ \t\n]" nil t)
			     (progn (beginning-of-line) (point))
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			   (point-max)))))
    ;; Handle the special case where point is followed by newline and eob.
    ;; Delete the line, leaving point at eob.
    (if (looking-at "^[ \t]*\n\\'")
	(delete-region (point) (point-max)))))
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(defun back-to-indentation ()
  "Move point to the first non-whitespace character on this line."
  (interactive)
  (beginning-of-line 1)
  (skip-chars-forward " \t"))

(defun newline-and-indent ()
  "Insert a newline, then indent according to major mode.
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Indentation is done using the value of `indent-line-function'.
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In programming language modes, this is the same as TAB.
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In some text modes, where TAB inserts a tab, this command indents to the
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column specified by the function `current-left-margin'."
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  (interactive "*")
  (delete-region (point) (progn (skip-chars-backward " \t") (point)))
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  (newline)
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  (indent-according-to-mode))

(defun reindent-then-newline-and-indent ()
  "Reindent current line, insert newline, then indent the new line.
Indentation of both lines is done according to the current major mode,
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which means calling the current value of `indent-line-function'.
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In programming language modes, this is the same as TAB.
In some text modes, where TAB inserts a tab, this indents to the
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column specified by the function `current-left-margin'."
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  (interactive "*")
  (save-excursion
    (delete-region (point) (progn (skip-chars-backward " \t") (point)))
    (indent-according-to-mode))
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  (newline)
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  (indent-according-to-mode))

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;; Internal subroutine of delete-char
(defun kill-forward-chars (arg)
  (if (listp arg) (setq arg (car arg)))
  (if (eq arg '-) (setq arg -1))
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  (kill-region (point) (forward-point arg)))
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;; Internal subroutine of backward-delete-char
(defun kill-backward-chars (arg)
  (if (listp arg) (setq arg (car arg)))
  (if (eq arg '-) (setq arg -1))
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  (kill-region (point) (forward-point (- arg))))
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(defun backward-delete-char-untabify (arg &optional killp)
  "Delete characters backward, changing tabs into spaces.
Delete ARG chars, and kill (save in kill ring) if KILLP is non-nil.
Interactively, ARG is the prefix arg (default 1)
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and KILLP is t if a prefix arg was specified."
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  (interactive "*p\nP")
  (let ((count arg))
    (save-excursion
      (while (and (> count 0) (not (bobp)))
	(if (= (preceding-char) ?\t)
	    (let ((col (current-column)))
	      (forward-char -1)
	      (setq col (- col (current-column)))
	      (insert-char ?\ col)
	      (delete-char 1)))
	(forward-char -1)
	(setq count (1- count)))))
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  (delete-backward-char arg killp))
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(defun zap-to-char (arg char)
  "Kill up to and including ARG'th occurrence of CHAR.
Goes backward if ARG is negative; error if CHAR not found."
  (interactive "p\ncZap to char: ")
  (kill-region (point) (progn
			 (search-forward (char-to-string char) nil nil arg)
;			 (goto-char (if (> arg 0) (1- (point)) (1+ (point))))
			 (point))))

(defun beginning-of-buffer (&optional arg)
  "Move point to the beginning of the buffer; leave mark at previous position.
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With arg N, put point N/10 of the way from the beginning.

If the buffer is narrowed, this command uses the beginning and size
of the accessible part of the buffer.
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Don't use this command in Lisp programs!
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\(goto-char (point-min)) is faster and avoids clobbering the mark."
  (interactive "P")
  (push-mark)
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  (let ((size (- (point-max) (point-min))))
    (goto-char (if arg
		   (+ (point-min)
		      (if (> size 10000)
			  ;; Avoid overflow for large buffer sizes!
			  (* (prefix-numeric-value arg)
			     (/ size 10))
			(/ (+ 10 (* size (prefix-numeric-value arg))) 10)))
		 (point-min))))
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  (if arg (forward-line 1)))

(defun end-of-buffer (&optional arg)
  "Move point to the end of the buffer; leave mark at previous position.
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With arg N, put point N/10 of the way from the end.

If the buffer is narrowed, this command uses the beginning and size
of the accessible part of the buffer.
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Don't use this command in Lisp programs!
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\(goto-char (point-max)) is faster and avoids clobbering the mark."
  (interactive "P")
  (push-mark)
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  (let ((size (- (point-max) (point-min))))
    (goto-char (if arg
		   (- (point-max)
		      (if (> size 10000)
			  ;; Avoid overflow for large buffer sizes!
			  (* (prefix-numeric-value arg)
			     (/ size 10))
			(/ (* size (prefix-numeric-value arg)) 10)))
		 (point-max))))
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  ;; If we went to a place in the middle of the buffer,
  ;; adjust it to the beginning of a line.
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  (if arg (forward-line 1)
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    ;; If the end of the buffer is not already on the screen,
    ;; then scroll specially to put it near, but not at, the bottom.
    (if (let ((old-point (point)))
	  (save-excursion
		    (goto-char (window-start))
		    (vertical-motion (window-height))
		    (< (point) old-point)))
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	(progn
	  (overlay-recenter (point))
	  (recenter -3)))))
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(defun mark-whole-buffer ()
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  "Put point at beginning and mark at end of buffer.
You probably should not use this function in Lisp programs;
it is usually a mistake for a Lisp function to use any subroutine
that uses or sets the mark."
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  (interactive)
  (push-mark (point))
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  (push-mark (point-max) nil t)
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  (goto-char (point-min)))

(defun count-lines-region (start end)
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  "Print number of lines and characters in the region."
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  (interactive "r")
  (message "Region has %d lines, %d characters"
	   (count-lines start end) (- end start)))

(defun what-line ()
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  "Print the current buffer line number and narrowed line number of point."
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  (interactive)
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  (let ((opoint (point)) start)
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    (save-excursion
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      (save-restriction
	(goto-char (point-min))
	(widen)
	(beginning-of-line)
	(setq start (point))
	(goto-char opoint)
	(beginning-of-line)
	(if (/= start 1)
	    (message "line %d (narrowed line %d)"
		     (1+ (count-lines 1 (point)))
		     (1+ (count-lines start (point))))
	  (message "Line %d" (1+ (count-lines 1 (point)))))))))

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(defun count-lines (start end)
  "Return number of lines between START and END.
This is usually the number of newlines between them,
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but can be one more if START is not equal to END
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and the greater of them is not at the start of a line."
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  (save-excursion
    (save-restriction
      (narrow-to-region start end)
      (goto-char (point-min))
      (if (eq selective-display t)
	  (save-match-data
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	    (let ((done 0))
	      (while (re-search-forward "[\n\C-m]" nil t 40)
		(setq done (+ 40 done)))
	      (while (re-search-forward "[\n\C-m]" nil t 1)
		(setq done (+ 1 done)))
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	      (goto-char (point-max))
	      (if (and (/= start end)
		       (not (bolp)))
		  (1+ done)
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		done)))
	(- (buffer-size) (forward-line (buffer-size)))))))
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(defun what-cursor-position (&optional detail)
  "Print info on cursor position (on screen and within buffer).
With prefix argument, print detailed info of a character on cursor position."
  (interactive "P")
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  (let* ((char (following-char))
	 (beg (point-min))
	 (end (point-max))
         (pos (point))
	 (total (buffer-size))
	 (percent (if (> total 50000)
		      ;; Avoid overflow from multiplying by 100!
		      (/ (+ (/ total 200) (1- pos)) (max (/ total 100) 1))
		    (/ (+ (/ total 2) (* 100 (1- pos))) (max total 1))))
	 (hscroll (if (= (window-hscroll) 0)
		      ""
		    (format " Hscroll=%d" (window-hscroll))))
	 (col (current-column)))
    (if (= pos end)
	(if (or (/= beg 1) (/= end (1+ total)))
	    (message "point=%d of %d(%d%%) <%d - %d>  column %d %s"
		     pos total percent beg end col hscroll)
	  (message "point=%d of %d(%d%%)  column %d %s"
		   pos total percent col hscroll))
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      (let ((str (if detail (format " %s" (split-char char)) "")))
	(if (or (/= beg 1) (/= end (1+ total)))
	    (message "Char: %s (0%o, %d, 0x%x) %s point=%d of %d(%d%%) <%d - %d>  column %d %s"
		     (if (< char 256)
			 (single-key-description char)
		       (char-to-string char))
		     char char char str pos total percent beg end col hscroll)
	  (message "Char: %s (0%o, %d, 0x%x)%s point=%d of %d(%d%%)  column %d %s"
		   (if (< char 256)
		       (single-key-description char)
		     (char-to-string char))
		   char char char str pos total percent col hscroll))))))
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(defun fundamental-mode ()
  "Major mode not specialized for anything in particular.
Other major modes are defined by comparison with this one."
  (interactive)
  (kill-all-local-variables))

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(defvar read-expression-map (cons 'keymap minibuffer-local-map)
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  "Minibuffer keymap used for reading Lisp expressions.")
(define-key read-expression-map "\M-\t" 'lisp-complete-symbol)

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(defvar read-expression-history nil)

;; We define this, rather than making `eval' interactive,
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;; for the sake of completion of names like eval-region, eval-current-buffer.
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(defun eval-expression (eval-expression-arg)
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  "Evaluate EXPRESSION and print value in minibuffer.
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Value is also consed on to front of the variable `values'."
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  (interactive
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   (list (read-from-minibuffer "Eval: "
			       nil read-expression-map t
			       'read-expression-history)))
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  (setq values (cons (eval eval-expression-arg) values))
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  (prin1 (car values) t))

(defun edit-and-eval-command (prompt command)
  "Prompting with PROMPT, let user edit COMMAND and eval result.
COMMAND is a Lisp expression.  Let user edit that expression in
the minibuffer, then read and evaluate the result."
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  (let ((command (read-from-minibuffer prompt
				       (prin1-to-string command)
				       read-expression-map t
				       '(command-history . 1))))
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    ;; If command was added to command-history as a string,
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    ;; get rid of that.  We want only evaluable expressions there.
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    (if (stringp (car command-history))
	(setq command-history (cdr command-history)))

    ;; If command to be redone does not match front of history,
    ;; add it to the history.
    (or (equal command (car command-history))
	(setq command-history (cons command command-history)))
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    (eval command)))

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(defun repeat-complex-command (arg)
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  "Edit and re-evaluate last complex command, or ARGth from last.
A complex command is one which used the minibuffer.
The command is placed in the minibuffer as a Lisp form for editing.
The result is executed, repeating the command as changed.
If the command has been changed or is not the most recent previous command
it is added to the front of the command history.
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You can use the minibuffer history commands \\<minibuffer-local-map>\\[next-history-element] and \\[previous-history-element]
to get different commands to edit and resubmit."
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  (interactive "p")
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  (let ((elt (nth (1- arg) command-history))
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	newcmd)
    (if elt
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	(progn
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	  (setq newcmd
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		(let ((print-level nil)
		      (minibuffer-history-position arg)
		      (minibuffer-history-sexp-flag t))
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		  (read-from-minibuffer
		   "Redo: " (prin1-to-string elt) read-expression-map t
		   (cons 'command-history arg))))
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	  ;; If command was added to command-history as a string,
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	  ;; get rid of that.  We want only evaluable expressions there.
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	  (if (stringp (car command-history))
	      (setq command-history (cdr command-history)))

	  ;; If command to be redone does not match front of history,
	  ;; add it to the history.
	  (or (equal newcmd (car command-history))
	      (setq command-history (cons newcmd command-history)))
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	  (eval newcmd))
      (ding))))
577

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(defvar minibuffer-history nil
  "Default minibuffer history list.
This is used for all minibuffer input
except when an alternate history list is specified.")
(defvar minibuffer-history-sexp-flag nil
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  "Non-nil when doing history operations on `command-history'.
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More generally, indicates that the history list being acted on
contains expressions rather than strings.")
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(setq minibuffer-history-variable 'minibuffer-history)
(setq minibuffer-history-position nil)
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(defvar minibuffer-history-search-history nil)
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(mapcar
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 (lambda (key-and-command)
   (mapcar
    (lambda (keymap-and-completionp)
      ;; Arg is (KEYMAP-SYMBOL . COMPLETION-MAP-P).
      ;; If the cdr of KEY-AND-COMMAND (the command) is a cons,
      ;; its car is used if COMPLETION-MAP-P is nil, its cdr if it is t.
      (define-key (symbol-value (car keymap-and-completionp))
	(car key-and-command)
	(let ((command (cdr key-and-command)))
	  (if (consp command)
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	      ;; (and ... nil) => ... turns back on the completion-oriented
	      ;; history commands which rms turned off since they seem to
	      ;; do things he doesn't like.
	      (if (and (cdr keymap-and-completionp) nil) ;XXX turned off
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		  (progn (error "EMACS BUG!") (cdr command))
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		(car command))
	    command))))
    '((minibuffer-local-map . nil)
      (minibuffer-local-ns-map . nil)
      (minibuffer-local-completion-map . t)
      (minibuffer-local-must-match-map . t)
      (read-expression-map . nil))))
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 '(("\en" . (next-history-element . next-complete-history-element))
   ([next] . (next-history-element . next-complete-history-element))
   ("\ep" . (previous-history-element . previous-complete-history-element))
   ([prior] . (previous-history-element . previous-complete-history-element))
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   ("\er" . previous-matching-history-element)
   ("\es" . next-matching-history-element)))
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(defvar minibuffer-text-before-history nil
  "Text that was in this minibuffer before any history commands.
This is nil if there have not yet been any history commands
in this use of the minibuffer.")

(add-hook 'minibuffer-setup-hook 'minibuffer-history-initialize)

(defun minibuffer-history-initialize ()
  (setq minibuffer-text-before-history nil))

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(defun previous-matching-history-element (regexp n)
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  "Find the previous history element that matches REGEXP.
\(Previous history elements refer to earlier actions.)
With prefix argument N, search for Nth previous match.
If N is negative, find the next or Nth next match."
  (interactive
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   (let* ((enable-recursive-minibuffers t)
	  (minibuffer-history-sexp-flag nil)
	  (regexp (read-from-minibuffer "Previous element matching (regexp): "
					nil
					minibuffer-local-map
					nil
					'minibuffer-history-search-history)))
     ;; Use the last regexp specified, by default, if input is empty.
     (list (if (string= regexp "")
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	       (if minibuffer-history-search-history
		   (car minibuffer-history-search-history)
		 (error "No previous history search regexp"))
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	     regexp)
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	   (prefix-numeric-value current-prefix-arg))))
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  (if (and (zerop minibuffer-history-position)
	   (null minibuffer-text-before-history))
      (setq minibuffer-text-before-history (buffer-string)))
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  (let ((history (symbol-value minibuffer-history-variable))
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	prevpos
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	(pos minibuffer-history-position))
    (while (/= n 0)
      (setq prevpos pos)
      (setq pos (min (max 1 (+ pos (if (< n 0) -1 1))) (length history)))
      (if (= pos prevpos)
	  (error (if (= pos 1)
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		     "No later matching history item"
		   "No earlier matching history item")))
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      (if (string-match regexp
			(if minibuffer-history-sexp-flag
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			    (let ((print-level nil))
			      (prin1-to-string (nth (1- pos) history)))
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			  (nth (1- pos) history)))
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	  (setq n (+ n (if (< n 0) 1 -1)))))
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    (setq minibuffer-history-position pos)
    (erase-buffer)
    (let ((elt (nth (1- pos) history)))
      (insert (if minibuffer-history-sexp-flag
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		  (let ((print-level nil))
		    (prin1-to-string elt))
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		elt)))
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      (goto-char (point-min)))
  (if (or (eq (car (car command-history)) 'previous-matching-history-element)
	  (eq (car (car command-history)) 'next-matching-history-element))
      (setq command-history (cdr command-history))))
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(defun next-matching-history-element (regexp n)
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  "Find the next history element that matches REGEXP.
\(The next history element refers to a more recent action.)
With prefix argument N, search for Nth next match.
If N is negative, find the previous or Nth previous match."
  (interactive
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   (let* ((enable-recursive-minibuffers t)
	  (minibuffer-history-sexp-flag nil)
	  (regexp (read-from-minibuffer "Next element matching (regexp): "
					nil
					minibuffer-local-map
					nil
					'minibuffer-history-search-history)))
     ;; Use the last regexp specified, by default, if input is empty.
     (list (if (string= regexp "")
	       (setcar minibuffer-history-search-history
		       (nth 1 minibuffer-history-search-history))
	     regexp)
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	   (prefix-numeric-value current-prefix-arg))))
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  (previous-matching-history-element regexp (- n)))
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(defun next-history-element (n)
  "Insert the next element of the minibuffer history into the minibuffer."
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  (interactive "p")
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  (or (zerop n)
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      (let ((narg (- minibuffer-history-position n))
	    (minimum (if minibuffer-default -1 0))
	    elt)
	(if (and (zerop minibuffer-history-position)
		 (null minibuffer-text-before-history))
	    (setq minibuffer-text-before-history (buffer-string)))
	(if (< narg minimum)
	    (error "End of history; no next item"))
	(if (> narg (length (symbol-value minibuffer-history-variable)))
	    (error "Beginning of history; no preceding item"))
	(erase-buffer)
	(setq minibuffer-history-position narg)
	(cond ((= narg -1)
	       (setq elt minibuffer-default))
	      ((= narg 0)
	       (setq elt minibuffer-text-before-history)
	       (setq minibuffer-text-before-history nil))
	      (t (setq elt (nth (1- minibuffer-history-position)
				(symbol-value minibuffer-history-variable)))))
	(insert
	 (if minibuffer-history-sexp-flag
	     (let ((print-level nil))
	       (prin1-to-string elt))
	   elt))
	(goto-char (point-min)))))
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(defun previous-history-element (n)
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  "Inserts the previous element of the minibuffer history into the minibuffer."
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  (interactive "p")
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  (next-history-element (- n)))
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(defun next-complete-history-element (n)
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  "Get next element of history which is a completion of minibuffer contents."
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  (interactive "p")
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  (let ((point-at-start (point)))
    (next-matching-history-element
     (concat "^" (regexp-quote (buffer-substring (point-min) (point)))) n)
    ;; next-matching-history-element always puts us at (point-min).
    ;; Move to the position we were at before changing the buffer contents.
    ;; This is still sensical, because the text before point has not changed.
    (goto-char point-at-start)))
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(defun previous-complete-history-element (n)
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  "\
Get previous element of history which is a completion of minibuffer contents."
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  (interactive "p")
  (next-complete-history-element (- n)))
753

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(defun goto-line (arg)
  "Goto line ARG, counting from line 1 at beginning of buffer."
  (interactive "NGoto line: ")
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  (setq arg (prefix-numeric-value arg))
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  (save-restriction
    (widen)
    (goto-char 1)
    (if (eq selective-display t)
	(re-search-forward "[\n\C-m]" nil 'end (1- arg))
      (forward-line (1- arg)))))

;Put this on C-x u, so we can force that rather than C-_ into startup msg
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(defalias 'advertised-undo 'undo)
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(defun undo (&optional arg)
  "Undo some previous changes.
Repeat this command to undo more changes.
A numeric argument serves as a repeat count."
  (interactive "*p")
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  ;; If we don't get all the way thru, make last-command indicate that
  ;; for the following command.
  (setq this-command t)
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  (let ((modified (buffer-modified-p))
	(recent-save (recent-auto-save-p)))
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    (or (eq (selected-window) (minibuffer-window))
	(message "Undo!"))
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    (or (eq last-command 'undo)
	(progn (undo-start)
	       (undo-more 1)))
    (undo-more (or arg 1))
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    ;; Don't specify a position in the undo record for the undo command.
    ;; Instead, undoing this should move point to where the change is.
    (let ((tail buffer-undo-list)
	  done)
      (while (and tail (not done) (not (null (car tail))))
	(if (integerp (car tail))
	    (progn
	      (setq done t)
	      (setq buffer-undo-list (delq (car tail) buffer-undo-list))))
	(setq tail (cdr tail))))
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    (and modified (not (buffer-modified-p))
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	 (delete-auto-save-file-if-necessary recent-save)))
  ;; If we do get all the way thru, make this-command indicate that.
  (setq this-command 'undo))
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(defvar pending-undo-list nil
  "Within a run of consecutive undo commands, list remaining to be undone.")

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(defun undo-start ()
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  "Set `pending-undo-list' to the front of the undo list.
The next call to `undo-more' will undo the most recently made change."
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  (if (eq buffer-undo-list t)
      (error "No undo information in this buffer"))
  (setq pending-undo-list buffer-undo-list))

(defun undo-more (count)
  "Undo back N undo-boundaries beyond what was already undone recently.
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Call `undo-start' to get ready to undo recent changes,
then call `undo-more' one or more times to undo them."
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  (or pending-undo-list
      (error "No further undo information"))
  (setq pending-undo-list (primitive-undo count pending-undo-list)))

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(defvar shell-command-history nil
  "History list for some commands that read shell commands.")

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(defvar shell-command-switch "-c"
  "Switch used to have the shell execute its command line argument.")

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(defun shell-command (command &optional output-buffer)
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  "Execute string COMMAND in inferior shell; display output, if any.
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If COMMAND ends in ampersand, execute it asynchronously.
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The output appears in the buffer `*Async Shell Command*'.
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That buffer is in shell mode.
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Otherwise, COMMAND is executed synchronously.  The output appears in the
buffer `*Shell Command Output*'.
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If the output is one line, it is displayed in the echo area *as well*,
but it is nonetheless available in buffer `*Shell Command Output*',
even though that buffer is not automatically displayed.
If there is no output, or if output is inserted in the current buffer,
then `*Shell Command Output*' is deleted.
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The optional second argument OUTPUT-BUFFER, if non-nil,
says to put the output in some other buffer.
If OUTPUT-BUFFER is a buffer or buffer name, put the output there.
If OUTPUT-BUFFER is not a buffer and not nil,
insert output in current buffer.  (This cannot be done asynchronously.)
In either case, the output is inserted after point (leaving mark after it)."
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  (interactive (list (read-from-minibuffer "Shell command: "
					   nil nil nil 'shell-command-history)
		     current-prefix-arg))
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  ;; Look for a handler in case default-directory is a remote file name.
  (let ((handler
	 (find-file-name-handler (directory-file-name default-directory)
				 'shell-command)))
    (if handler
	(funcall handler 'shell-command command output-buffer)
      (if (and output-buffer
	       (not (or (bufferp output-buffer)  (stringp output-buffer))))
	  (progn (barf-if-buffer-read-only)
		 (push-mark)
		 ;; We do not use -f for csh; we will not support broken use of
		 ;; .cshrcs.  Even the BSD csh manual says to use
		 ;; "if ($?prompt) exit" before things which are not useful
		 ;; non-interactively.  Besides, if someone wants their other
		 ;; aliases for shell commands then they can still have them.
		 (call-process shell-file-name nil t nil
			       shell-command-switch command)
		 ;; This is like exchange-point-and-mark, but doesn't
		 ;; activate the mark.  It is cleaner to avoid activation,
		 ;; even though the command loop would deactivate the mark
		 ;; because we inserted text.
		 (goto-char (prog1 (mark t)
			      (set-marker (mark-marker) (point)
					  (current-buffer)))))
	;; Preserve the match data in case called from a program.
	(save-match-data
	  (if (string-match "[ \t]*&[ \t]*$" command)
	      ;; Command ending with ampersand means asynchronous.
	      (let ((buffer (get-buffer-create
			     (or output-buffer "*Async Shell Command*")))
		    (directory default-directory)
		    proc)
		;; Remove the ampersand.
		(setq command (substring command 0 (match-beginning 0)))
		;; If will kill a process, query first.
		(setq proc (get-buffer-process buffer))
		(if proc
		    (if (yes-or-no-p "A command is running.  Kill it? ")
			(kill-process proc)
		      (error "Shell command in progress")))
		(save-excursion
		  (set-buffer buffer)
		  (setq buffer-read-only nil)
		  (erase-buffer)
		  (display-buffer buffer)
		  (setq default-directory directory)
		  (setq proc (start-process "Shell" buffer shell-file-name 
					    shell-command-switch command))
		  (setq mode-line-process '(":%s"))
		  (require 'shell) (shell-mode)
		  (set-process-sentinel proc 'shell-command-sentinel)
		  ))
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	    (shell-command-on-region (point) (point) command output-buffer)
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	    ))))))
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;; We have a sentinel to prevent insertion of a termination message
;; in the buffer itself.
(defun shell-command-sentinel (process signal)
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  (if (memq (process-status process) '(exit signal))
      (message "%s: %s." 
	       (car (cdr (cdr (process-command process))))
	       (substring signal 0 -1))))
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(defun shell-command-on-region (start end command
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				      &optional output-buffer replace)
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  "Execute string COMMAND in inferior shell with region as input.
Normally display output (if any) in temp buffer `*Shell Command Output*';
Prefix arg means replace the region with it.
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The noninteractive arguments are START, END, COMMAND, OUTPUT-BUFFER, REPLACE.
If REPLACE is non-nil, that means insert the output
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in place of text from START to END, putting point and mark around it.
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If the output is one line, it is displayed in the echo area,
but it is nonetheless available in buffer `*Shell Command Output*'
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even though that buffer is not automatically displayed.
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If there is no output, or if output is inserted in the current buffer,
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then `*Shell Command Output*' is deleted.
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If the optional fourth argument OUTPUT-BUFFER is non-nil,
that says to put the output in some other buffer.
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If OUTPUT-BUFFER is a buffer or buffer name, put the output there.
If OUTPUT-BUFFER is not a buffer and not nil,
insert output in the current buffer.
In either case, the output is inserted after point (leaving mark after it)."
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  (interactive (let ((string
		      ;; Do this before calling region-beginning
		      ;; and region-end, in case subprocess output
		      ;; relocates them while we are in the minibuffer.
		      (read-from-minibuffer "Shell command on region: "
					    nil nil nil
					    'shell-command-history)))
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		 ;; call-interactively recognizes region-beginning and
		 ;; region-end specially, leaving them in the history.
		 (list (region-beginning) (region-end)
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		       string
		       current-prefix-arg
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		       current-prefix-arg)))
  (if (or replace
	  (and output-buffer
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	       (not (or (bufferp output-buffer) (stringp output-buffer))))
	  (equal (buffer-name (current-buffer)) "*Shell Command Output*"))
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      ;; Replace specified region with output from command.
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      (let ((swap (and replace (< start end))))
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	;; Don't muck with mark unless REPLACE says we should.
	(goto-char start)
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	(and replace (push-mark))
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	(call-process-region start end shell-file-name t t nil
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			     shell-command-switch command)
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	(let ((shell-buffer (get-buffer "*Shell Command Output*")))
	  (and shell-buffer (not (eq shell-buffer (current-buffer)))
	       (kill-buffer shell-buffer)))
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	;; Don't muck with mark unless REPLACE says we should.
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	(and replace swap (exchange-point-and-mark)))
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    ;; No prefix argument: put the output in a temp buffer,
    ;; replacing its entire contents.
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    (let ((buffer (get-buffer-create
		   (or output-buffer "*Shell Command Output*")))
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	  (success nil))
      (unwind-protect
	  (if (eq buffer (current-buffer))
	      ;; If the input is the same buffer as the output,
	      ;; delete everything but the specified region,
	      ;; then replace that region with the output.
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	      (progn (setq buffer-read-only nil)
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		     (delete-region (max start end) (point-max))
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		     (delete-region (point-min) (min start end))
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		     (call-process-region (point-min) (point-max)
					  shell-file-name t t nil
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					  shell-command-switch command)
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		     (setq success t))
	    ;; Clear the output buffer, then run the command with output there.
	    (save-excursion
	      (set-buffer buffer)
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	      (setq buffer-read-only nil)
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	      (erase-buffer))
	    (call-process-region start end shell-file-name
				 nil buffer nil
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				 shell-command-switch command)
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	    (setq success t))
	;; Report the amount of output.
	(let ((lines (save-excursion
		       (set-buffer buffer)
		       (if (= (buffer-size) 0)
			   0
			 (count-lines (point-min) (point-max))))))
	  (cond ((= lines 0)
		 (if success
		     (message "(Shell command completed with no output)"))
		 (kill-buffer buffer))
		((and success (= lines 1))
		 (message "%s"
			  (save-excursion
			    (set-buffer buffer)
			    (goto-char (point-min))
			    (buffer-substring (point)
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					      (progn (end-of-line) (point))))))
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		(t 
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		 (save-excursion
		   (set-buffer buffer)
		   (goto-char (point-min)))
		 (display-buffer buffer))))))))
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(defun shell-command-to-string (command)
  "Execute shell command COMMAND and return its output as a string."
  (with-output-to-string
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    (with-current-buffer
      standard-output
      (call-process shell-file-name nil t nil shell-command-switch command))))
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(defvar universal-argument-map
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  (let ((map (make-sparse-keymap)))
    (define-key map [t] 'universal-argument-other-key)
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    (define-key map (vector meta-prefix-char t) 'universal-argument-other-key)
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    (define-key map [switch-frame] nil)
    (define-key map [?\C-u] 'universal-argument-more)
    (define-key map [?-] 'universal-argument-minus)
    (define-key map [?0] 'digit-argument)
    (define-key map [?1] 'digit-argument)
    (define-key map [?2] 'digit-argument)
    (define-key map [?3] 'digit-argument)
    (define-key map [?4] 'digit-argument)
    (define-key map [?5] 'digit-argument)
    (define-key map [?6] 'digit-argument)
    (define-key map [?7] 'digit-argument)
    (define-key map [?8] 'digit-argument)
    (define-key map [?9] 'digit-argument)
    map)
  "Keymap used while processing \\[universal-argument].")

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(defvar universal-argument-num-events nil
  "Number of argument-specifying events read by `universal-argument'.
`universal-argument-other-key' uses this to discard those events
from (this-command-keys), and reread only the final command.")

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(defun universal-argument ()
  "Begin a numeric argument for the following command.
Digits or minus sign following \\[universal-argument] make up the numeric argument.
\\[universal-argument] following the digits or minus sign ends the argument.
\\[universal-argument] without digits or minus sign provides 4 as argument.
Repeating \\[universal-argument] without digits or minus sign
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 multiplies the argument by 4 each time.
For some commands, just \\[universal-argument] by itself serves as a flag
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which is different in effect from any particular numeric argument.
These commands include \\[set-mark-command] and \\[start-kbd-macro]."
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  (interactive)
  (setq prefix-arg (list 4))
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  (setq universal-argument-num-events (length (this-command-keys)))
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  (setq overriding-terminal-local-map universal-argument-map))
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;; A subsequent C-u means to multiply the factor by 4 if we've typed
;; nothing but C-u's; otherwise it means to terminate the prefix arg.
(defun universal-argument-more (arg)
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  (interactive "P")
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  (if (consp arg)
      (setq prefix-arg (list (* 4 (car arg))))
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    (if (eq arg '-)
	(setq prefix-arg (list -4))
      (setq prefix-arg arg)
      (setq overriding-terminal-local-map nil)))
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  (setq universal-argument-num-events (length (this-command-keys))))
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(defun negative-argument (arg)
  "Begin a negative numeric argument for the next command.
\\[universal-argument] following digits or minus sign ends the argument."
  (interactive "P")
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  (cond ((integerp arg)
	 (setq prefix-arg (- arg)))
	((eq arg '-)
	 (setq prefix-arg nil))
	(t
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	 (setq prefix-arg '-)))
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  (setq universal-argument-num-events (length (this-command-keys)))
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  (setq overriding-terminal-local-map universal-argument-map))