Various docstring and commentary fixes, including

[bpt/emacs.git] / lisp / replace.el

;;; replace.el --- replace commands for Emacs.

;; Copyright (C) 1985, 86, 87, 92, 94, 96, 1997 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, Inc., 59 Temple Place - Suite 330,
;; Boston, MA 02111-1307, USA.

;;; Commentary:

;; This package supplies the string and regular-expression replace functions
;; documented in the Emacs user's manual.

;;; Code:

(defcustom case-replace t
  "*Non-nil means query-replace should preserve case in replacements."
  :type 'boolean
  :group 'matching)

(defvar query-replace-history nil)

(defvar query-replace-interactive nil
  "Non-nil means `query-replace' uses the last search string.
That becomes the \"string to replace\".")

(defun query-replace-read-args (string regexp-flag)
  (let (from to)
    (if query-replace-interactive
	(setq from (car (if regexp-flag regexp-search-ring search-ring)))
      (setq from (read-from-minibuffer (format "%s: " string)
				       nil nil nil
				       'query-replace-history nil t)))
    (setq to (read-from-minibuffer (format "%s %s with: " string from)
				   nil nil nil
				   'query-replace-history nil t))
    (list from to current-prefix-arg)))

(defun query-replace (from-string to-string &optional arg)
  "Replace some occurrences of FROM-STRING with TO-STRING.
As each match is found, the user must type a character saying
what to do with it.  For directions, type \\[help-command] at that time.

In Transient Mark mode, if the mark is active, operate on the contents
of the region.  Otherwise, operate from point to the end of the buffer.

If `query-replace-interactive' is non-nil, the last incremental search
string is used as FROM-STRING--you don't have to specify it with the
minibuffer.

Preserves case in each replacement if `case-replace' and `case-fold-search'
are non-nil and FROM-STRING has no uppercase letters.
\(Preserving case means that if the string matched is all caps, or capitalized,
then its replacement is upcased or capitalized.)

Third arg DELIMITED (prefix arg if interactive), if non-nil, means replace
only matches surrounded by word boundaries.

To customize possible responses, change the \"bindings\" in `query-replace-map'."
  (interactive (query-replace-read-args "Query replace" nil))
  (perform-replace from-string to-string t nil arg))

(define-key esc-map "%" 'query-replace)

(defun query-replace-regexp (regexp to-string &optional arg)
  "Replace some things after point matching REGEXP with TO-STRING.
As each match is found, the user must type a character saying
what to do with it.  For directions, type \\[help-command] at that time.

In Transient Mark mode, if the mark is active, operate on the contents
of the region.  Otherwise, operate from point to the end of the buffer.

If `query-replace-interactive' is non-nil, the last incremental search
regexp is used as REGEXP--you don't have to specify it with the
minibuffer.

Preserves case in each replacement if `case-replace' and `case-fold-search'
are non-nil and REGEXP has no uppercase letters.
Third arg DELIMITED (prefix arg if interactive), if non-nil, means replace
only matches surrounded by word boundaries.
In TO-STRING, `\\&' stands for whatever matched the whole of REGEXP,
and `\\=\\N' (where N is a digit) stands for
 whatever what matched the Nth `\\(...\\)' in REGEXP."
  (interactive (query-replace-read-args "Query replace regexp" t))
  (perform-replace regexp to-string t t arg))

(defun map-query-replace-regexp (regexp to-strings &optional arg)
  "Replace some matches for REGEXP with various strings, in rotation.
The second argument TO-STRINGS contains the replacement strings, separated
by spaces.  This command works like `query-replace-regexp' except
that each successive replacement uses the next successive replacement string,
wrapping around from the last such string to the first.

In Transient Mark mode, if the mark is active, operate on the contents
of the region.  Otherwise, operate from point to the end of the buffer.

Non-interactively, TO-STRINGS may be a list of replacement strings.

If `query-replace-interactive' is non-nil, the last incremental search
regexp is used as REGEXP--you don't have to specify it with the minibuffer.

A prefix argument N says to use each replacement string N times
before rotating to the next."
  (interactive
   (let (from to)
     (setq from (if query-replace-interactive
		    (car regexp-search-ring)
		  (read-from-minibuffer "Map query replace (regexp): "
					nil nil nil
					'query-replace-history nil t)))
     (setq to (read-from-minibuffer
	       (format "Query replace %s with (space-separated strings): "
		       from)
	       nil nil nil
	       'query-replace-history nil t))
     (list from to current-prefix-arg)))
  (let (replacements)
    (if (listp to-strings)
	(setq replacements to-strings)
      (while (/= (length to-strings) 0)
	(if (string-match " " to-strings)
	    (setq replacements
		  (append replacements
			  (list (substring to-strings 0
					   (string-match " " to-strings))))
		  to-strings (substring to-strings
				       (1+ (string-match " " to-strings))))
	  (setq replacements (append replacements (list to-strings))
		to-strings ""))))
    (perform-replace regexp replacements t t nil arg)))

(defun replace-string (from-string to-string &optional delimited)
  "Replace occurrences of FROM-STRING with TO-STRING.
Preserve case in each match if `case-replace' and `case-fold-search'
are non-nil and FROM-STRING has no uppercase letters.
\(Preserving case means that if the string matched is all caps, or capitalized,
then its replacement is upcased or capitalized.)

In Transient Mark mode, if the mark is active, operate on the contents
of the region.  Otherwise, operate from point to the end of the buffer.

Third arg DELIMITED (prefix arg if interactive), if non-nil, means replace
only matches surrounded by word boundaries.

If `query-replace-interactive' is non-nil, the last incremental search
string is used as FROM-STRING--you don't have to specify it with the
minibuffer.

This function is usually the wrong thing to use in a Lisp program.
What you probably want is a loop like this:
  (while (search-forward FROM-STRING nil t)
    (replace-match TO-STRING nil t))
which will run faster and will not set the mark or print anything.
\(You may need a more complex loop if FROM-STRING can match the null string
and TO-STRING is also null.)"
  (interactive (query-replace-read-args "Replace string" nil))
  (perform-replace from-string to-string nil nil delimited))

(defun replace-regexp (regexp to-string &optional delimited)
  "Replace things after point matching REGEXP with TO-STRING.
Preserve case in each match if `case-replace' and `case-fold-search'
are non-nil and REGEXP has no uppercase letters.
Third arg DELIMITED (prefix arg if interactive), if non-nil, means replace
only matches surrounded by word boundaries.
In TO-STRING, `\\&' stands for whatever matched the whole of REGEXP,
and `\\=\\N' (where N is a digit) stands for
 whatever what matched the Nth `\\(...\\)' in REGEXP.

In Transient Mark mode, if the mark is active, operate on the contents
of the region.  Otherwise, operate from point to the end of the buffer.

If `query-replace-interactive' is non-nil, the last incremental search
regexp is used as REGEXP--you don't have to specify it with the minibuffer.

This function is usually the wrong thing to use in a Lisp program.
What you probably want is a loop like this:
  (while (re-search-forward REGEXP nil t)
    (replace-match TO-STRING nil nil))
which will run faster and will not set the mark or print anything."
  (interactive (query-replace-read-args "Replace regexp" t))
  (perform-replace regexp to-string nil t delimited))
\f
(defvar regexp-history nil
  "History list for some commands that read regular expressions.")

(defalias 'delete-non-matching-lines 'keep-lines)
(defun keep-lines (regexp)
  "Delete all lines except those containing matches for REGEXP.
A match split across lines preserves all the lines it lies in.
Applies to all lines after point."
  (interactive (list (read-from-minibuffer
		      "Keep lines (containing match for regexp): "
		      nil nil nil 'regexp-history nil t)))
  (save-excursion
    (or (bolp) (forward-line 1))
    (let ((start (point)))
      (while (not (eobp))
	;; Start is first char not preserved by previous match.
	(if (not (re-search-forward regexp nil 'move))
	    (delete-region start (point-max))
	  (let ((end (save-excursion (goto-char (match-beginning 0))
				     (beginning-of-line)
				     (point))))
	    ;; Now end is first char preserved by the new match.
	    (if (< start end)
		(delete-region start end))))
	(setq start (save-excursion (forward-line 1)
				    (point)))
	;; If the match was empty, avoid matching again at same place.
	(and (not (eobp)) (= (match-beginning 0) (match-end 0))
	     (forward-char 1))))))

(defalias 'delete-matching-lines 'flush-lines)
(defun flush-lines (regexp)
  "Delete lines containing matches for REGEXP.
If a match is split across lines, all the lines it lies in are deleted.
Applies to lines after point."
  (interactive (list (read-from-minibuffer
		      "Flush lines (containing match for regexp): "
		      nil nil nil 'regexp-history nil t)))
  (save-excursion
    (while (and (not (eobp))
		(re-search-forward regexp nil t))
      (delete-region (save-excursion (goto-char (match-beginning 0))
				     (beginning-of-line)
				     (point))
		     (progn (forward-line 1) (point))))))

(defalias 'count-matches 'how-many)
(defun how-many (regexp)
  "Print number of matches for REGEXP following point."
  (interactive (list(read-from-minibuffer
		     "How many matches for (regexp): "
		     nil nil nil 'regexp-history nil t)))
  (let ((count 0) opoint)
    (save-excursion
     (while (and (not (eobp))
		 (progn (setq opoint (point))
			(re-search-forward regexp nil t)))
       (if (= opoint (point))
	   (forward-char 1)
	 (setq count (1+ count))))
     (message "%d occurrences" count))))
\f
(defvar occur-mode-map ())
(if occur-mode-map
    ()
  (setq occur-mode-map (make-sparse-keymap))
  (define-key occur-mode-map [mouse-2] 'occur-mode-mouse-goto)
  (define-key occur-mode-map "\C-c\C-c" 'occur-mode-goto-occurrence)
  (define-key occur-mode-map "\C-m" 'occur-mode-goto-occurrence)
  (define-key occur-mode-map "\M-n" 'occur-next)
  (define-key occur-mode-map "\M-p" 'occur-prev)
  (define-key occur-mode-map "g" 'revert-buffer))


(defvar occur-buffer nil
  "Name of buffer for last occur.")


(defvar occur-nlines nil
  "Number of lines of context to show around matching line.")

(defvar occur-command-arguments nil
  "Arguments that were given to `occur' when it made this buffer.")

(put 'occur-mode 'mode-class 'special)

(defun occur-mode ()
  "Major mode for output from \\[occur].
\\<occur-mode-map>Move point to one of the items in this buffer, then use
\\[occur-mode-goto-occurrence] to go to the occurrence that the item refers to.
Alternatively, click \\[occur-mode-mouse-goto] on an item to go to it.

\\{occur-mode-map}"
  (kill-all-local-variables)
  (use-local-map occur-mode-map)
  (setq major-mode 'occur-mode)
  (setq mode-name "Occur")
  (make-local-variable 'revert-buffer-function)
  (setq revert-buffer-function 'occur-revert-function)
  (make-local-variable 'occur-buffer)
  (make-local-variable 'occur-nlines)
  (make-local-variable 'occur-command-arguments)
  (run-hooks 'occur-mode-hook))

;; Handle revert-buffer for *Occur* buffers.
(defun occur-revert-function (ignore1 ignore2)
  (let ((args occur-command-arguments ))
    (save-excursion
      (set-buffer occur-buffer)
      (apply 'occur args))))

(defun occur-mode-mouse-goto (event)
  "In Occur mode, go to the occurrence whose line you click on."
  (interactive "e")
  (let (buffer pos)
    (save-excursion
      (set-buffer (window-buffer (posn-window (event-end event))))
      (save-excursion
	(goto-char (posn-point (event-end event)))
	(setq pos (occur-mode-find-occurrence))
	(setq buffer occur-buffer)))
    (pop-to-buffer buffer)
    (goto-char (marker-position pos))))

(defun occur-mode-find-occurrence ()
  (if (or (null occur-buffer)
	  (null (buffer-name occur-buffer)))
      (progn
	(setq occur-buffer nil)
	(error "Buffer in which occurrences were found is deleted")))
  (let ((pos (get-text-property (point) 'occur)))
    (if (null pos)
	(error "No occurrence on this line")
      pos)))

(defun occur-mode-goto-occurrence ()
  "Go to the occurrence the current line describes."
  (interactive)
  (let ((pos (occur-mode-find-occurrence)))
    (pop-to-buffer occur-buffer)
    (goto-char (marker-position pos))))

(defun occur-next (&optional n)
  "Move to the Nth (default 1) next match in the *Occur* buffer."
  (interactive "p")
  (if (not n) (setq n 1))
  (let ((r))
    (while (> n 0)
      (if (get-text-property (point) 'occur-point)
	  (forward-char 1))
      (setq r (next-single-property-change (point) 'occur-point))
      (if r
	  (goto-char r)
	(error "no more matches"))
      (setq n (1- n)))))



(defun occur-prev (&optional n)
  "Move to the Nth (default 1) previous match in the *Occur* buffer."
  (interactive "p")
  (if (not n) (setq n 1))
  (let ((r))
    (while (> n 0)
    
      (setq r (get-text-property (point) 'occur-point))
      (if r (forward-char -1))
      
      (setq r (previous-single-property-change (point) 'occur-point))
      (if r
	  (goto-char (- r 1))
	(error "no earlier matches"))
      
      (setq n (1- n)))))
\f
(defcustom list-matching-lines-default-context-lines 0
  "*Default number of context lines to include around a `list-matching-lines'
match.  A negative number means to include that many lines before the match.
A positive number means to include that many lines both before and after."
  :type 'integer
  :group 'matching)

(defalias 'list-matching-lines 'occur)

(defvar list-matching-lines-face 'bold
  "*Face used by M-x list-matching-lines to show the text that matches.
If the value is nil, don't highlight the matching portions specially.")

(defun occur (regexp &optional nlines)
  "Show all lines in the current buffer containing a match for REGEXP.

If a match spreads across multiple lines, all those lines are shown.

Each line is displayed with NLINES lines before and after, or -NLINES
before if NLINES is negative.
NLINES defaults to `list-matching-lines-default-context-lines'.
Interactively it is the prefix arg.

The lines are shown in a buffer named `*Occur*'.
It serves as a menu to find any of the occurrences in this buffer.
\\<occur-mode-map>\\[describe-mode] in that buffer will explain how.

If REGEXP contains upper case characters (excluding those preceded by `\\'),
the matching is case-sensitive."
  (interactive
   (list (let* ((default (car regexp-history))
		(input
		 (read-from-minibuffer
		  (if default
		      (format "List lines matching regexp (default `%s'): "
			      default)
		    "List lines matching regexp: ")
		  nil nil nil 'regexp-history default t)))
	   (set-text-properties 0 (length input) nil input)
	   input)
	 current-prefix-arg))
  (let ((nlines (if nlines
		    (prefix-numeric-value nlines)
		  list-matching-lines-default-context-lines))
	(first t)
	;;flag to prevent printing separator for first match
	(occur-num-matches 0)
	(buffer (current-buffer))
	(dir default-directory)
	(linenum 1)
	(prevpos 
	 ;;position of most recent match
	 (point-min))
	(case-fold-search  (and case-fold-search
				(isearch-no-upper-case-p regexp t)))
	(final-context-start
	 ;; Marker to the start of context immediately following
	 ;; the matched text in *Occur*.
	 (make-marker)))
;;;	(save-excursion
;;;	  (beginning-of-line)
;;;	  (setq linenum (1+ (count-lines (point-min) (point))))
;;;	  (setq prevpos (point)))
    (save-excursion
      (goto-char (point-min))
      ;; Check first whether there are any matches at all.
      (if (not (re-search-forward regexp nil t))
	  (message "No matches for `%s'" regexp)
	;; Back up, so the search loop below will find the first match.
	(goto-char (match-beginning 0))
	(with-output-to-temp-buffer "*Occur*"
	  (save-excursion
	    (set-buffer standard-output)
	    (setq default-directory dir)
	    ;; We will insert the number of lines, and "lines", later.
	    (insert " matching ")
	    (let ((print-escape-newlines t))
	      (prin1 regexp))
	    (insert " in buffer " (buffer-name buffer) ?. ?\n)
	    (occur-mode)
	    (setq occur-buffer buffer)
	    (setq occur-nlines nlines)
	    (setq occur-command-arguments
		  (list regexp nlines)))
	  (if (eq buffer standard-output)
	      (goto-char (point-max)))
	  (save-excursion
	    ;; Find next match, but give up if prev match was at end of buffer.
	    (while (and (not (= prevpos (point-max)))
			(re-search-forward regexp nil t))
	      (goto-char (match-beginning 0))
	      (beginning-of-line)
	      (save-match-data
		(setq linenum (+ linenum (count-lines prevpos (point)))))
	      (setq prevpos (point))
	      (goto-char (match-end 0))
	      (let* ((start
		      ;;start point of text in source buffer to be put
		      ;;into *Occur*
		      (save-excursion
			      (goto-char (match-beginning 0))
			      (forward-line (if (< nlines 0)
						nlines
					      (- nlines)))
			      (point)))
		     (end	
		      ;; end point of text in source buffer to be put
		      ;; into *Occur*
		      (save-excursion 
			(goto-char (match-end 0))
			(if (> nlines 0)
			    (forward-line (1+ nlines))
			  (forward-line 1))
			(point)))
		     (match-beg
		      ;; Amount of context before matching text
		      (- (match-beginning 0) start))
		     (match-len		
		      ;; Length of matching text
		      (- (match-end 0) (match-beginning 0)))
		     (tag (format "%5d" linenum))
		     (empty (make-string (length tag) ?\ ))
		     tem		
		     insertion-start
		     ;; Number of lines of context to show for current match.
		     occur-marker	
		     ;; Marker pointing to end of match in source buffer.
		     (text-beg
		      ;; Marker pointing to start of text for one
		      ;; match in *Occur*.
		      (make-marker))
		     (text-end 
		      ;; Marker pointing to end of text for one match
		      ;; in *Occur*.
		      (make-marker))
		     )
		(save-excursion
		  (setq occur-marker (make-marker))
		  (set-marker occur-marker (point))
		  (set-buffer standard-output)
		  (setq occur-num-matches (1+ occur-num-matches))
		  (or first (zerop nlines)
		      (insert "--------\n"))
		  (setq first nil)

		  ;; Insert matching text including context lines from
		  ;; source buffer into *Occur*
		  (set-marker text-beg (point))
		  (setq insertion-start (point))
		  (insert-buffer-substring buffer start end)
		  (or (and (/= (+ start match-beg) end)
			   (with-current-buffer buffer
			     (eq (char-before end) ?\n)))
		      (insert "\n"))
		  (set-marker final-context-start 
			      (+ (- (point) (- end (match-end 0)))
				 (if (save-excursion
				       (set-buffer buffer)
				       (save-excursion
					 (goto-char (match-end 0))
					 (end-of-line)
					 (bolp)))
				     1 0)))
		  (set-marker text-end (point))
		  
		  ;; Highlight text that was matched.
		  (if list-matching-lines-face
		      (put-text-property
		       (+ (marker-position text-beg) match-beg)
		       (+ (marker-position text-beg) match-beg match-len)
		       'face list-matching-lines-face))

		  ;; `occur-point' property is used by occur-next and
		  ;; occur-prev to move between matching lines.
		  (put-text-property
		   (+ (marker-position text-beg) match-beg match-len)
		   (+ (marker-position text-beg) match-beg match-len 1)
		   'occur-point t)
		  
		  ;; Now go back to the start of the matching text
		  ;; adding the space and colon to the start of each line.
		  (goto-char insertion-start)
		  ;; Insert space and colon for lines of context before match.
		  (setq tem (if (< linenum nlines)
				(- nlines linenum)
			      nlines))
		  (while (> tem 0)
		    (insert empty ?:)
		    (forward-line 1)
		    (setq tem (1- tem)))

		  ;; Insert line number and colon for the lines of
		  ;; matching text.
		  (let ((this-linenum linenum))
		    (while (< (point) final-context-start)
		      (if (null tag)
			  (setq tag (format "%5d" this-linenum)))
		      (insert tag ?:)
		      (forward-line 1)
		      (setq tag nil)
		      (setq this-linenum (1+ this-linenum)))
		    (while (and (not (eobp)) (<= (point) final-context-start))
		      (insert empty ?:)
		      (forward-line 1)
		      (setq this-linenum (1+ this-linenum))))

		  ;; Insert space and colon for lines of context after match.
		  (while (and (< (point) (point-max)) (< tem nlines))
		    (insert empty ?:)
		    (forward-line 1)
		    (setq tem (1+ tem)))
		  
		  ;; Add text properties.  The `occur' prop is used to
		  ;; store the marker of the matching text in the
		  ;; source buffer.
		  (put-text-property (marker-position text-beg)
				     (- (marker-position text-end) 1)
				     'mouse-face 'highlight)
		  (put-text-property (marker-position text-beg)
				     (marker-position text-end)
				     'occur occur-marker)
		  (goto-char (point-max)))
		(forward-line 1)))
	    (set-buffer standard-output)
	    ;; Go back to top of *Occur* and finish off by printing the
	    ;; number of matching lines.
	    (goto-char (point-min))
	    (let ((message-string
		   (if (= occur-num-matches 1)
		       "1 line"
		     (format "%d lines" occur-num-matches))))
	      (insert message-string)
	      (if (interactive-p)
		  (message "%s matched" message-string)))))))))
\f
;; It would be nice to use \\[...], but there is no reasonable way
;; to make that display both SPC and Y.
(defconst query-replace-help
  "Type Space or `y' to replace one match, Delete or `n' to skip to next,
RET or `q' to exit, Period to replace one match and exit,
Comma to replace but not move point immediately,
C-r to enter recursive edit (\\[exit-recursive-edit] to get out again),
C-w to delete match and recursive edit,
C-l to clear the screen, redisplay, and offer same replacement again,
! to replace all remaining matches with no more questions,
^ to move point back to previous match."
  "Help message while in query-replace")

(defvar query-replace-map (make-sparse-keymap)
  "Keymap that defines the responses to questions in `query-replace'.
The \"bindings\" in this map are not commands; they are answers.
The valid answers include `act', `skip', `act-and-show',
`exit', `act-and-exit', `edit', `delete-and-edit', `recenter',
`automatic', `backup', `exit-prefix', and `help'.")

(define-key query-replace-map " " 'act)
(define-key query-replace-map "\d" 'skip)
(define-key query-replace-map [delete] 'skip)
(define-key query-replace-map [backspace] 'skip)
(define-key query-replace-map "y" 'act)
(define-key query-replace-map "n" 'skip)
(define-key query-replace-map "Y" 'act)
(define-key query-replace-map "N" 'skip)
(define-key query-replace-map "," 'act-and-show)
(define-key query-replace-map "q" 'exit)
(define-key query-replace-map "\r" 'exit)
(define-key query-replace-map [return] 'exit)
(define-key query-replace-map "." 'act-and-exit)
(define-key query-replace-map "\C-r" 'edit)
(define-key query-replace-map "\C-w" 'delete-and-edit)
(define-key query-replace-map "\C-l" 'recenter)
(define-key query-replace-map "!" 'automatic)
(define-key query-replace-map "^" 'backup)
(define-key query-replace-map "\C-h" 'help)
(define-key query-replace-map [f1] 'help)
(define-key query-replace-map [help] 'help)
(define-key query-replace-map "?" 'help)
(define-key query-replace-map "\C-g" 'quit)
(define-key query-replace-map "\C-]" 'quit)
(define-key query-replace-map "\e" 'exit-prefix)
(define-key query-replace-map [escape] 'exit-prefix)

(defun perform-replace (from-string replacements
		        query-flag regexp-flag delimited-flag
			&optional repeat-count map)
  "Subroutine of `query-replace'.  Its complexity handles interactive queries.
Don't use this in your own program unless you want to query and set the mark
just as `query-replace' does.  Instead, write a simple loop like this:
  (while (re-search-forward \"foo[ \t]+bar\" nil t)
    (replace-match \"foobar\" nil nil))
which will run faster and probably do exactly what you want."
  (or map (setq map query-replace-map))
  (and query-flag minibuffer-auto-raise
       (raise-frame (window-frame (minibuffer-window))))
  (let ((nocasify (not (and case-fold-search case-replace
			    (string-equal from-string
					  (downcase from-string)))))
	(literal (not regexp-flag))
	(search-function (if regexp-flag 're-search-forward 'search-forward))
	(search-string from-string)
	(real-match-data nil)		; the match data for the current match
	(next-replacement nil)
	(replacement-index 0)
	(keep-going t)
	(stack nil)
	(next-rotate-count 0)
	(replace-count 0)
	(nonempty-match nil)

	;; If non-nil, it is marker saying where in the buffer to stop.
	(limit nil)

	;; Data for the next match.  If a cons, it has the same format as
	;; (match-data); otherwise it is t if a match is possible at point.
	(match-again t)

	(message
	 (if query-flag
	     (substitute-command-keys
	      "Query replacing %s with %s: (\\<query-replace-map>\\[help] for help) "))))

    ;; If region is active, in Transient Mark mode, operate on region.
    (if (and transient-mark-mode mark-active)
	(progn
	  (setq limit (copy-marker (region-end)))
	  (goto-char (region-beginning))
	  (deactivate-mark)))
    (if (stringp replacements)
	(setq next-replacement replacements)
      (or repeat-count (setq repeat-count 1)))
    (if delimited-flag
	(setq search-function 're-search-forward
	      search-string (concat "\\b"
				    (if regexp-flag from-string
				      (regexp-quote from-string))
				    "\\b")))
    (push-mark)
    (undo-boundary)
    (unwind-protect
	;; Loop finding occurrences that perhaps should be replaced.
	(while (and keep-going
		    (not (eobp))
		    ;; Use the next match if it is already known;
		    ;; otherwise, search for a match after moving forward
		    ;; one char if progress is required.
		    (setq real-match-data
			  (if (consp match-again)
			      (progn (goto-char (nth 1 match-again))
				     match-again)
			    (and (or match-again
				     (progn
				       (forward-char 1)
				       (not (eobp))))
				 (funcall search-function search-string limit t)
				 ;; For speed, use only integers and
				 ;; reuse the list used last time.
				 (match-data t real-match-data)))))

	  ;; Record whether the match is nonempty, to avoid an infinite loop
	  ;; repeatedly matching the same empty string.
	  (setq nonempty-match
		(/= (nth 0 real-match-data) (nth 1 real-match-data)))

	  ;; If the match is empty, record that the next one can't be adjacent.
	  ;; Otherwise, if matching a regular expression, do the next
	  ;; match now, since the replacement for this match may
	  ;; affect whether the next match is adjacent to this one.
	  (setq match-again
		(and nonempty-match
		     (or (not regexp-flag)
			 (and (looking-at search-string)
			      (match-data)))))

	  ;; If time for a change, advance to next replacement string.
	  (if (and (listp replacements)
		   (= next-rotate-count replace-count))
	      (progn
		(setq next-rotate-count
		      (+ next-rotate-count repeat-count))
		(setq next-replacement (nth replacement-index replacements))
		(setq replacement-index (% (1+ replacement-index) (length replacements)))))
	  (if (not query-flag)
	      (progn
		(store-match-data real-match-data)
		(replace-match next-replacement nocasify literal)
		(setq replace-count (1+ replace-count)))
	    (undo-boundary)
	    (let (done replaced key def)
	      ;; Loop reading commands until one of them sets done,
	      ;; which means it has finished handling this occurrence.
	      (while (not done)
		(store-match-data real-match-data)
		(replace-highlight (match-beginning 0) (match-end 0))
		;; Bind message-log-max so we don't fill up the message log
		;; with a bunch of identical messages.
		(let ((message-log-max nil))
		  (message message from-string next-replacement))
		(setq key (read-event))
		;; Necessary in case something happens during read-event
		;; that clobbers the match data.
		(store-match-data real-match-data)
		(setq key (vector key))
		(setq def (lookup-key map key))
		;; Restore the match data while we process the command.
		(cond ((eq def 'help)
		       (with-output-to-temp-buffer "*Help*"
			 (princ
			  (concat "Query replacing "
				  (if regexp-flag "regexp " "")
				  from-string " with "
				  next-replacement ".\n\n"
				  (substitute-command-keys
				   query-replace-help)))
			 (save-excursion
			   (set-buffer standard-output)
			   (help-mode))))
		      ((eq def 'exit)
		       (setq keep-going nil)
		       (setq done t))
		      ((eq def 'backup)
		       (if stack
			   (let ((elt (car stack)))
			     (goto-char (car elt))
			     (setq replaced (eq t (cdr elt)))
			     (or replaced
				 (store-match-data (cdr elt)))
			     (setq stack (cdr stack)))
			 (message "No previous match")
			 (ding 'no-terminate)
			 (sit-for 1)))
		      ((eq def 'act)
		       (or replaced
			   (progn
			     (replace-match next-replacement nocasify literal)
			     (setq replace-count (1+ replace-count))))
		       (setq done t replaced t))
		      ((eq def 'act-and-exit)
		       (or replaced
			   (progn
			     (replace-match next-replacement nocasify literal)
			     (setq replace-count (1+ replace-count))))
		       (setq keep-going nil)
		       (setq done t replaced t))
		      ((eq def 'act-and-show)
		       (if (not replaced)
			   (progn
			     (replace-match next-replacement nocasify literal)
			     (setq replace-count (1+ replace-count))
			     (setq replaced t))))
		      ((eq def 'automatic)
		       (or replaced
			   (progn
			     (replace-match next-replacement nocasify literal)
			     (setq replace-count (1+ replace-count))))
		       (setq done t query-flag nil replaced t))
		      ((eq def 'skip)
		       (setq done t))
		      ((eq def 'recenter)
		       (recenter nil))
		      ((eq def 'edit)
		       (store-match-data
			(prog1 (match-data)
			  (save-excursion (recursive-edit))))
		       ;; Before we make the replacement,
		       ;; decide whether the search string
		       ;; can match again just after this match.
		       (if (and regexp-flag nonempty-match)
			   (setq match-again (and (looking-at search-string)
						  (match-data)))))
		      ((eq def 'delete-and-edit)
		       (delete-region (match-beginning 0) (match-end 0))
		       (store-match-data
			(prog1 (match-data)
			  (save-excursion (recursive-edit))))
		       (setq replaced t))
		      ;; Note: we do not need to treat `exit-prefix'
		      ;; specially here, since we reread
		      ;; any unrecognized character.
		      (t
		       (setq this-command 'mode-exited)
		       (setq keep-going nil)
		       (setq unread-command-events
			     (append (listify-key-sequence key)
				     unread-command-events))
		       (setq done t))))
	      ;; Record previous position for ^ when we move on.
	      ;; Change markers to numbers in the match data
	      ;; since lots of markers slow down editing.
	      (setq stack
		    (cons (cons (point)
				(or replaced (match-data t)))
			  stack)))))
      (replace-dehighlight))
    (or unread-command-events
	(message "Replaced %d occurrence%s"
		 replace-count
		 (if (= replace-count 1) "" "s")))
    (and keep-going stack)))

(defcustom query-replace-highlight t
  "*Non-nil means to highlight words during query replacement."
  :type 'boolean
  :group 'matching)

(defvar replace-overlay nil)

(defun replace-dehighlight ()
  (and replace-overlay
       (progn
	 (delete-overlay replace-overlay)
	 (setq replace-overlay nil))))

(defun replace-highlight (start end)
  (and query-replace-highlight
       (progn
	 (or replace-overlay
	     (progn
	       (setq replace-overlay (make-overlay start end))
	       (overlay-put replace-overlay 'face
			    (if (internal-find-face 'query-replace)
				'query-replace 'region))))
	 (move-overlay replace-overlay start end (current-buffer)))))

;;; replace.el ends here