simple.el

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

;; Copyright (C) 1985, 1986, 1987, 1993, 1994 Free Software Foundation, Inc.

;; 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
;; the Free Software Foundation; either version 2, or (at your option)
;; 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
;; along with GNU Emacs; see the file COPYING.  If not, write to
;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.

;;; Commentary:

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

;;; Code:

(defun open-line (arg)
  "Insert a newline and leave point before it.
If there is a fill prefix, insert the fill prefix on the new line
if the line would have been empty.
With arg N, insert N newlines."
  (interactive "*p")
  (let* ((do-fill-prefix (and fill-prefix (bolp)))
	 (loc (point)))
    (while (> arg 0)
      (if do-fill-prefix (insert-and-inherit fill-prefix))
      (newline 1)
      (setq arg (1- arg)))
    (goto-char loc))
  (end-of-line))

(defun split-line ()
  "Split current line, moving portion beyond point vertically down."
  (interactive "*")
  (skip-chars-forward " \t")
  (let ((col (current-column))
	(pos (point)))
    (newline 1)
    (indent-to col 0)
    (goto-char pos)))

(defun quoted-insert (arg)
  "Read next input character and insert it.
This is useful for inserting control characters.
You may also type up to 3 octal digits, to insert a character with that code.

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."
  (interactive "*p")
  (let ((char (if (or (not overwrite-mode)
		      (eq overwrite-mode 'overwrite-mode-binary))
		  (read-quoted-char)
		(read-char))))
    (if (> arg 0)
	(if (eq overwrite-mode 'overwrite-mode-binary)
	    (delete-char arg)))
    (while (> arg 0)
      (insert-and-inherit char)
      (setq arg (1- arg)))))

(defun delete-indentation (&optional arg)
  "Join this line to previous and fix up whitespace at join.
If there is a fill prefix, delete it from the beginning of this line.
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)))
	;; If the second line started with the fill prefix,
	;; delete the prefix.
	(if (and fill-prefix
		 (<= (+ (point) (length fill-prefix)) (point-max))
		 (string= fill-prefix
			  (buffer-substring (point)
					    (+ (point) (length fill-prefix)))))
	    (delete-region (point) (+ (point) (length fill-prefix))))
	(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.
On nonblank line, delete any immediately following blank lines."
  (interactive "*")
  (let (thisblank singleblank)
    (save-excursion
      (beginning-of-line)
      (setq thisblank (looking-at "[ \t]*$"))
      ;; Set singleblank if there is just one blank line here.
      (setq singleblank
	    (and thisblank
		 (not (looking-at "[ \t]*\n[ \t]*$"))
		 (or (bobp)
		     (progn (forward-line -1)
			    (not (looking-at "[ \t]*$")))))))
    ;; Delete preceding blank lines, and this one too if it's the only one.
    (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)))))
    ;; Delete following blank lines, unless the current line is blank
    ;; and there are no following blank lines.
    (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))
			   (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)))))

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

;; Internal subroutine of delete-char
(defun kill-forward-chars (arg)
  (if (listp arg) (setq arg (car arg)))
  (if (eq arg '-) (setq arg -1))
  (kill-region (point) (+ (point) arg)))

;; Internal subroutine of backward-delete-char
(defun kill-backward-chars (arg)
  (if (listp arg) (setq arg (car arg)))
  (if (eq arg '-) (setq arg -1))
  (kill-region (point) (- (point) arg)))

(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)
and KILLP is t if a prefix arg was specified."
  (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)))))
  (delete-backward-char arg killp)
  ;; In overwrite mode, back over columns while clearing them out,
  ;; unless at end of line.
  (and overwrite-mode (not (eolp))
       (save-excursion (insert-char ?\  arg))))

(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.
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.

Don't use this command in Lisp programs!
\(goto-char (point-min)) is faster and avoids clobbering the mark."
  (interactive "P")
  (push-mark)
  (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))))
  (if arg (forward-line 1)))

(defun end-of-buffer (&optional arg)
  "Move point to the end of the buffer; leave mark at previous position.
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.

Don't use this command in Lisp programs!
\(goto-char (point-max)) is faster and avoids clobbering the mark."
  (interactive "P")
  (push-mark)
  (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))))
  ;; If we went to a place in the middle of the buffer,
  ;; adjust it to the beginning of a line.
  (if arg (forward-line 1)
    ;; 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)))
	(progn
	  (overlay-recenter (point))
	  (recenter -3)))))

(defun mark-whole-buffer ()
  "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."
  (interactive)
  (push-mark (point))
  (push-mark (point-max) nil t)
  (goto-char (point-min)))

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

(defun what-line ()
  "Print the current line number (in the buffer) of point."
  (interactive)
  (save-restriction
    (widen)
    (save-excursion
      (beginning-of-line)
      (message "Line %d"
	       (1+ (count-lines 1 (point)))))))

(defun count-lines (start end)
  "Return number of lines between START and END.
This is usually the number of newlines between them,
but can be one more if START is not equal to END
and the greater of them is not at the start of a line."
  (save-excursion
    (save-restriction
      (narrow-to-region start end)
      (goto-char (point-min))
      (if (eq selective-display t)
	  (save-match-data
	    (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)))
	      (goto-char (point-max))
	      (if (and (/= start end)
		       (not (bolp)))
		  (1+ done)
		done)))
	(- (buffer-size) (forward-line (buffer-size)))))))

(defun what-cursor-position ()
  "Print info on cursor position (on screen and within buffer)."
  (interactive)
  (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))
      (if (or (/= beg 1) (/= end (1+ total)))
	  (message "Char: %s (0%o, %d, 0x%x)  point=%d of %d(%d%%) <%d - %d>  column %d %s"
		   (single-key-description char) char char char pos total percent beg end col hscroll)
	(message "Char: %s (0%o, %d, 0x%x)  point=%d of %d(%d%%)  column %d %s"
		 (single-key-description char) char char char pos total percent col hscroll)))))

(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))

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

(put 'eval-expression 'disabled t)

(defvar read-expression-history nil)

;; We define this, rather than making `eval' interactive,
;; for the sake of completion of names like eval-region, eval-current-buffer.
(defun eval-expression (expression)
  "Evaluate EXPRESSION and print value in minibuffer.
Value is also consed on to front of the variable `values'."
  (interactive
   (list (read-from-minibuffer "Eval: "
			       nil read-expression-map t
			       'read-expression-history)))
  (setq values (cons (eval expression) values))
  (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."
  (let ((command (read-from-minibuffer prompt
				       (prin1-to-string command)
				       read-expression-map t
				       '(command-history . 1))))
    ;; If command was added to command-history as a string,
    ;; get rid of that.  We want only evallable expressions there.
    (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)))
    (eval command)))

(defun repeat-complex-command (arg)
  "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.
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."
  (interactive "p")
  (let ((elt (nth (1- arg) command-history))
	(minibuffer-history-position arg)
	(minibuffer-history-sexp-flag t)
	newcmd)
    (if elt
	(progn
	  (setq newcmd
		(let ((print-level nil))
		  (read-from-minibuffer
		   "Redo: " (prin1-to-string elt) read-expression-map t
		   (cons 'command-history arg))))

	  ;; If command was added to command-history as a string,
	  ;; get rid of that.  We want only evallable expressions there.
	  (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)))
	  (eval newcmd))
      (ding))))

(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
  "Non-nil when doing history operations on `command-history'.
More generally, indicates that the history list being acted on
contains expressions rather than strings.")
(setq minibuffer-history-variable 'minibuffer-history)
(setq minibuffer-history-position nil)
(defvar minibuffer-history-search-history nil)

(mapcar
 (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)
	      ;; (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
		  (progn (error "EMACS BUG!") (cdr command))
		(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))))
 '(("\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))
   ("\er" . previous-matching-history-element)
   ("\es" . next-matching-history-element)))

(defun previous-matching-history-element (regexp n)
  "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
   (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 "")
	       (setcar minibuffer-history-search-history
		       (nth 1 minibuffer-history-search-history))
	     regexp)
	   (prefix-numeric-value current-prefix-arg))))
  (let ((history (symbol-value minibuffer-history-variable))
	prevpos
	(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)
		     "No later matching history item"
		   "No earlier matching history item")))
      (if (string-match regexp
			(if minibuffer-history-sexp-flag
			    (let ((print-level nil))
			      (prin1-to-string (nth (1- pos) history)))
			  (nth (1- pos) history)))
	  (setq n (+ n (if (< n 0) 1 -1)))))
    (setq minibuffer-history-position pos)
    (erase-buffer)
    (let ((elt (nth (1- pos) history)))
      (insert (if minibuffer-history-sexp-flag
		  (let ((print-level nil))
		    (prin1-to-string elt))
		elt)))
      (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))))

(defun next-matching-history-element (regexp n)
  "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
   (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)
	   (prefix-numeric-value current-prefix-arg))))
  (previous-matching-history-element regexp (- n)))

(defun next-history-element (n)
  "Insert the next element of the minibuffer history into the minibuffer."
  (interactive "p")
  (or (zerop n)
      (let ((narg (min (max 1 (- minibuffer-history-position n))
		       (length (symbol-value minibuffer-history-variable)))))
	    (if (or (zerop narg)
		    (= minibuffer-history-position narg))
		(error (if (if (zerop narg)
			       (> n 0)
			     (= minibuffer-history-position 1))
		       "End of history; no next item"
		     "Beginning of history; no preceding item"))
	  (erase-buffer)
	  (setq minibuffer-history-position narg)
	  (let ((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))))))

(defun previous-history-element (n)
  "Inserts the previous element of the minibuffer history into the minibuffer."
  (interactive "p")
  (next-history-element (- n)))

(defun next-complete-history-element (n)
  "Get next element of history which is a completion of minibuffer contents."
  (interactive "p")
  (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)))

(defun previous-complete-history-element (n)
  "\
Get previous element of history which is a completion of minibuffer contents."
  (interactive "p")
  (next-complete-history-element (- n)))

(defun goto-line (arg)
  "Goto line ARG, counting from line 1 at beginning of buffer."
  (interactive "NGoto line: ")
  (setq arg (prefix-numeric-value arg))
  (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
(define-function 'advertised-undo 'undo)

(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")
  ;; If we don't get all the way thru, make last-command indicate that
  ;; for the following command.
  (setq this-command t)
  (let ((modified (buffer-modified-p))
	(recent-save (recent-auto-save-p)))
    (or (eq (selected-window) (minibuffer-window))
	(message "Undo!"))
    (or (eq last-command 'undo)
	(progn (undo-start)
	       (undo-more 1)))
    (undo-more (or arg 1))
    ;; 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))))
    (and modified (not (buffer-modified-p))
	 (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))

(defvar pending-undo-list nil
  "Within a run of consecutive undo commands, list remaining to be undone.")

(defun undo-start ()
  "Set `pending-undo-list' to the front of the undo list.
The next call to `undo-more' will undo the most recently made change."
  (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.
Call `undo-start' to get ready to undo recent changes,
then call `undo-more' one or more times to undo them."
  (or pending-undo-list
      (error "No further undo information"))
  (setq pending-undo-list (primitive-undo count pending-undo-list)))

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

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

(defun shell-command (command &optional output-buffer)
  "Execute string COMMAND in inferior shell; display output, if any.
If COMMAND ends in ampersand, execute it asynchronously.
The output appears in the buffer `*Shell Command*'.

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)."
  (interactive (list (read-from-minibuffer "Shell command: "
					   nil nil nil 'shell-command-history)
		     current-prefix-arg))
  (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 ($?prompt) exit" before things which are not useful
	     ;; non-interactively.  Besides, if someone wants their other
	     ;; aliases for shell commands then they can still have them.
	     (call-process shell-file-name nil t nil
			   shell-command-switch command)
	     ;; This is like exchange-point-and-mark, but doesn't activate the mark.
	     ;; It is cleaner to avoid activation, even though the command
	     ;; loop would deactivate the mark because we inserted text.
	     (goto-char (prog1 (mark t)
			  (set-marker (mark-marker) (point)
				      (current-buffer)))))
    ;; Preserve the match data in case called from a program.
    (let ((data (match-data)))
      (unwind-protect
	  (if (string-match "[ \t]*&[ \t]*$" command)
	      ;; Command ending with ampersand means asynchronous.
	      (let ((buffer (get-buffer-create
			     (or output-buffer "*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"))
		  (set-process-sentinel proc 'shell-command-sentinel)
		  (set-process-filter proc 'shell-command-filter)
		  ))
	    (shell-command-on-region (point) (point) command nil))
	(store-match-data data)))))

;; We have a sentinel to prevent insertion of a termination message
;; in the buffer itself.
(defun shell-command-sentinel (process signal)
  (if (and (memq (process-status process) '(exit signal))
	   (buffer-name (process-buffer process)))
      (progn
	(message "%s: %s." 
		 (car (cdr (cdr (process-command process))))
		 (substring signal 0 -1))
	(save-excursion
	  (set-buffer (process-buffer process))
	  (setq mode-line-process nil))
	(delete-process process))))

(defun shell-command-filter (proc string)
  ;; Do save-excursion by hand so that we can leave point numerically unchanged
  ;; despite an insertion immediately after it.
  (let* ((obuf (current-buffer))
	 (buffer (process-buffer proc))
	 opoint
	 (window (get-buffer-window buffer))
	 (pos (window-start window)))
    (unwind-protect
	(progn
	  (set-buffer buffer)
	  (or (= (point) (point-max))
	      (setq opoint (point)))
	  (goto-char (point-max))
	  (insert-before-markers string))
      ;; insert-before-markers moved this marker: set it back.
      (set-window-start window pos)
      ;; Finish our save-excursion.
      (if opoint
	  (goto-char opoint))
      (set-buffer obuf))))

(defun shell-command-on-region (start end command
				      &optional output-buffer interactive)
  "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.
Noninteractive args are START, END, COMMAND, FLAG.
Noninteractively FLAG means insert output in place of text from START to END,
and put point at the end, but don't alter the mark.

If the output is one line, it is displayed in the echo area,
but it is nonetheless available in buffer `*Shell Command Output*'
even though that buffer is not automatically displayed.  If there is no output
or output is inserted in the current buffer then `*Shell Command Output*' is
deleted.

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 the current buffer.
In either case, the output is inserted after point (leaving mark after it)."
  (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)))
		 (list (region-beginning) (region-end)
		       string
		       current-prefix-arg
		       (prefix-numeric-value current-prefix-arg))))
  (if (and output-buffer
	   (not (or (bufferp output-buffer) (stringp output-buffer))))
      ;; Replace specified region with output from command.
      (let ((swap (and interactive (< (point) (mark)))))
	;; Don't muck with mark
	;; unless called interactively.
	(and interactive (push-mark))
	(call-process-region start end shell-file-name t t nil
			     shell-command-switch command)
	(let ((shell-buffer (get-buffer "*Shell Command Output*")))
	  (and shell-buffer (not (eq shell-buffer (current-buffer)))
	       (kill-buffer shell-buffer)))
	(and interactive swap (exchange-point-and-mark)))
    ;; No prefix argument: put the output in a temp buffer,
    ;; replacing its entire contents.
    (let ((buffer (get-buffer-create
		   (or output-buffer "*Shell Command Output*")))
	  (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.
	      (progn (setq buffer-read-only nil)
		     (delete-region end (point-max))
		     (delete-region (point-min) start)
		     (call-process-region (point-min) (point-max)
					  shell-file-name t t nil
					  shell-command-switch command)
		     (setq success t))
	    ;; Clear the output buffer, then run the command with output there.
	    (save-excursion
	      (set-buffer buffer)
	      (setq buffer-read-only nil)
	      (erase-buffer))
	    (call-process-region start end shell-file-name
				 nil buffer nil
				 shell-command-switch command)
	    (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)
					      (progn (end-of-line) (point))))))
		(t 
		 (set-window-start (display-buffer buffer) 1))))))))

(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
 multiplies the argument by 4 each time."
  (interactive nil)
  (let ((factor 4)
	key)
;;    (describe-arg (list factor) 1)
    (setq key (read-key-sequence nil t))
    (while (equal (key-binding key) 'universal-argument)
      (setq factor (* 4 factor))
;;      (describe-arg (list factor) 1)
      (setq key (read-key-sequence nil t)))
    (prefix-arg-internal key factor nil)))

(defun prefix-arg-internal (key factor value)
  (let ((sign 1))
    (if (and (numberp value) (< value 0))
	(setq sign -1 value (- value)))
    (if (eq value '-)
	(setq sign -1 value nil))
;;    (describe-arg value sign)
    (while (equal key "-")
      (setq sign (- sign) factor nil)
;;      (describe-arg value sign)
      (setq key (read-key-sequence nil t)))
    (while (and (stringp key)
		(= (length key) 1)
		(not (string< key "0"))
		(not (string< "9" key)))
      (setq value (+ (* (if (numberp value) value 0) 10)
		     (- (aref key 0) ?0))
	    factor nil)
;;      (describe-arg value sign)
      (setq key (read-key-sequence nil t)))
    (setq prefix-arg
	  (cond (factor (list factor))
		((numberp value) (* value sign))
		((= sign -1) '-)))
    ;; Calling universal-argument after digits
    ;; terminates the argument but is ignored.
    (if (eq (key-binding key) 'universal-argument)
	(progn
	  (describe-arg value sign)
	  (setq key (read-key-sequence nil t))))
    (setq unread-command-events (listify-key-sequence key))))

(defun describe-arg (value sign)
  (cond ((numberp value)
	 (message "Arg: %d" (* value sign)))
	((consp value)
	 (message "Arg: [%d]" (car value)))
	((< sign 0)
	 (message "Arg: -"))))

(defun digit-argument (arg)
  "Part of the numeric argument for the next command.
\\[universal-argument] following digits or minus sign ends the argument."
  (interactive "P")
  (prefix-arg-internal (char-to-string (logand last-command-char ?\177))
		       nil arg))

(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")
  (prefix-arg-internal "-" nil arg))

(defun forward-to-indentation (arg)
  "Move forward ARG lines and position at first nonblank character."
  (interactive "p")
  (forward-line arg)
  (skip-chars-forward " \t"))

(defun backward-to-indentation (arg)
  "Move backward ARG lines and position at first nonblank character."
  (interactive "p")
  (forward-line (- arg))
  (skip-chars-forward " \t"))

(defvar kill-whole-line nil
  "*If non-nil, `kill-line' with no arg at beg of line kills the whole line.")

(defun kill-line (&optional arg)
  "Kill the rest of the current line; if no nonblanks there, kill thru newline.
With prefix argument, kill that many lines from point.
Negative arguments kill lines backward.

When calling from a program, nil means \"no arg\",
a number counts as a prefix arg.

If `kill-whole-line' is non-nil, then kill the whole line
when given no argument at the beginning of a line."
  (interactive "P")
  (kill-region (point)
	       ;; It is better to move point to the other end of the kill
	       ;; before killing.  That way, in a read-only buffer, point
	       ;; moves across the text that is copied to the kill ring.
	       ;; The choice has no effect on undo now that undo records
	       ;; the value of point from before the command was run.
	       (progn
		 (if arg
		     (forward-line (prefix-numeric-value arg))
		   (if (eobp)
		       (signal 'end-of-buffer nil))
		   (if (or (looking-at "[ \t]*$") (and kill-whole-line (bolp)))
		       (forward-line 1)
		     (end-of-line)))
		 (point))))

;;;; Window system cut and paste hooks.

(defvar interprogram-cut-function nil
  "Function to call to make a killed region available to other programs.

Most window systems provide some sort of facility for cutting and
pasting text between the windows of different programs.
This variable holds a function that Emacs calls whenever text
is put in the kill ring, to make the new kill available to other
programs.

The function takes one or two arguments.
The first argument, TEXT, is a string containing
the text which should be made available.
The second, PUSH, if non-nil means this is a \"new\" kill;
nil means appending to an \"old\" kill.")

(defvar interprogram-paste-function nil
  "Function to call to get text cut from other programs.

Most window systems provide some sort of facility for cutting and
pasting text between the windows of different programs.
This variable holds a function that Emacs calls to obtain
text that other programs have provided for pasting.

The function should be called with no arguments.  If the function
returns nil, then no other program has provided such text, and the top
of the Emacs kill ring should be used.  If the function returns a
string, that string should be put in the kill ring as the latest kill.

Note that the function should return a string only if a program other
than Emacs has provided a string for pasting; if Emacs provided the
most recent string, the function should return nil.  If it is
difficult to tell whether Emacs or some other program provided the
current string, it is probably good enough to return nil if the string
is equal (according to `string=') to the last text Emacs provided.")



;;;; The kill ring data structure.

(defvar kill-ring nil
  "List of killed text sequences.
Since the kill ring is supposed to interact nicely with cut-and-paste
facilities offered by window systems, use of this variable should
interact nicely with `interprogram-cut-function' and
`interprogram-paste-function'.  The functions `kill-new',
`kill-append', and `current-kill' are supposed to implement this
interaction; you may want to use them instead of manipulating the kill
ring directly.")

(defconst kill-ring-max 30
  "*Maximum length of kill ring before oldest elements are thrown away.")

(defvar kill-ring-yank-pointer nil
  "The tail of the kill ring whose car is the last thing yanked.")

(defun kill-new (string &optional replace)
  "Make STRING the latest kill in the kill ring.
Set the kill-ring-yank pointer to point to it.
If `interprogram-cut-function' is non-nil, apply it to STRING.
Optional second argument REPLACE non-nil means that STRING will replace
the front of the kill ring, rather than being added to the list."
  (and (fboundp 'menu-bar-update-yank-menu)
       (menu-bar-update-yank-menu string (and replace (car kill-ring))))
  (if replace
      (setcar kill-ring string)
    (setq kill-ring (cons string kill-ring))
    (if (> (length kill-ring) kill-ring-max)
	(setcdr (nthcdr (1- kill-ring-max) kill-ring) nil)))
  (setq kill-ring-yank-pointer kill-ring)
  (if interprogram-cut-function
      (funcall interprogram-cut-function string t)))

(defun kill-append (string before-p)
  "Append STRING to the end of the latest kill in the kill ring.
If BEFORE-P is non-nil, prepend STRING to the kill.
If `interprogram-cut-function' is set, pass the resulting kill to
it."
  (kill-new (if before-p
		(concat string (car kill-ring))
	      (concat (car kill-ring) string)) t))

(defun current-kill (n &optional do-not-move)
  "Rotate the yanking point by N places, and then return that kill.
If N is zero, `interprogram-paste-function' is set, and calling it
returns a string, then that string is added to the front of the
kill ring and returned as the latest kill.
If optional arg DO-NOT-MOVE is non-nil, then don't actually move the 
yanking point; just return the Nth kill forward."
  (let ((interprogram-paste (and (= n 0)
				 interprogram-paste-function
				 (funcall interprogram-paste-function))))
    (if interprogram-paste
	(progn
	  ;; Disable the interprogram cut function when we add the new
	  ;; text to the kill ring, so Emacs doesn't try to own the
	  ;; selection, with identical text.
	  (let ((interprogram-cut-function nil))
	    (kill-new interprogram-paste))
	  interprogram-paste)
      (or kill-ring (error "Kill ring is empty"))
      (let ((ARGth-kill-element
	     (nthcdr (mod (- n (length kill-ring-yank-pointer))
			  (length kill-ring))
		     kill-ring)))
	(or do-not-move
	    (setq kill-ring-yank-pointer ARGth-kill-element))
	(car ARGth-kill-element)))))



;;;; Commands for manipulating the kill ring.

(defvar kill-read-only-ok nil
  "*Non-nil means don't signal an error for killing read-only text.")

(defun kill-region (beg end)
  "Kill between point and mark.
The text is deleted but saved in the kill ring.
The command \\[yank] can retrieve it from there.
\(If you want to kill and then yank immediately, use \\[copy-region-as-kill].)
If the buffer is read-only, Emacs will beep and refrain from deleting
the text, but put the text in the kill ring anyway.  This means that
you can use the killing commands to copy text from a read-only buffer.

This is the primitive for programs to kill text (as opposed to deleting it).
Supply two arguments, character numbers indicating the stretch of text
 to be killed.
Any command that calls this function is a \"kill command\".
If the previous command was also a kill command,
the text killed this time appends to the text killed last time
to make one entry in the kill ring."
  (interactive "r")
  (cond

   ;; If the buffer is read-only, we should beep, in case the person
   ;; just isn't aware of this.  However, there's no harm in putting
   ;; the region's text in the kill ring, anyway.
   ((or (and buffer-read-only (not inhibit-read-only))
	(text-property-not-all beg end 'read-only nil))
    (copy-region-as-kill beg end)
    ;; This should always barf, and give us the correct error.
    (if kill-read-only-ok
	(message "Read only text copied to kill ring")
      (setq this-command 'kill-region)
      (barf-if-buffer-read-only)))

   ;; In certain cases, we can arrange for the undo list and the kill
   ;; ring to share the same string object.  This code does that.
   ((not (or (eq buffer-undo-list t)
	     (eq last-command 'kill-region)
	     ;; Use = since positions may be numbers or markers.
	     (= beg end)))