--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/lisp/packages/emerge.el	Mon Aug 13 08:45:50 2007 +0200
@@ -0,0 +1,3234 @@
+;;; emerge.el --- merge diffs under Emacs control
+
+;;; The author has placed this file in the public domain.
+
+;; Author: Dale R. Worley <drw@math.mit.edu>
+;; Version: 5xemacs
+;; Keywords: unix, tools
+
+;; This software was created by Dale R. Worley and is
+;; distributed free of charge.  It is placed in the public domain and
+;; permission is granted to anyone to use, duplicate, modify and redistribute
+;; it provided that this notice is attached.
+
+;; Dale R. Worley provides absolutely NO WARRANTY OF ANY KIND
+;; with respect to this software.  The entire risk as to the quality and
+;; performance of this software is with the user.  IN NO EVENT WILL DALE
+;; R. WORLEY BE LIABLE TO ANYONE FOR ANY DAMAGES ARISING OUT THE
+;; USE OF THIS SOFTWARE, INCLUDING, WITHOUT LIMITATION, DAMAGES RESULTING FROM
+;; LOST DATA OR LOST PROFITS, OR FOR ANY SPECIAL, INCIDENTAL OR CONSEQUENTIAL
+;; DAMAGES.
+
+;;; Synched up with: FSF 19.30.
+
+;; LCD Archive Entry:
+;; emerge|Dale R. Worley|drw@math.mit.edu
+;; |File merge
+;; |92-12-11|version 5 gamma|~/packages/emerge.el.Z
+
+;;; Code
+
+(defmacro emerge-eval-in-buffer (buffer &rest forms)
+  "Macro to switch to BUFFER, evaluate FORMS, returns to original buffer.
+Differs from `save-excursion' in that it doesn't save the point and mark."
+  (` (let ((StartBuffer (current-buffer)))
+    (unwind-protect
+	(progn
+	  (set-buffer (, buffer))
+	  (,@ forms))
+      (set-buffer StartBuffer)))))
+
+(defconst emerge-xemacs-p (not (not (string-match "XEmacs" emacs-version)))
+  "Non-nil if this is XEmacs.  Don't alter manually, because it also
+turns on work-arounds for bugs.")
+
+(defmacro emerge-defvar-local (var value doc) 
+  "Defines SYMBOL as an advertised variable.
+Performs a defvar, then executes `make-variable-buffer-local' on
+the variable.  Also sets the `preserved' property, so that
+`kill-all-local-variables' (called by major-mode setting commands)
+won't destroy Emerge control variables."
+  (` (progn
+       (defvar (, var) (, value) (, doc))
+       (make-variable-buffer-local '(, var))
+       (put '(, var)
+	    ;; This "if" can't be optimized by having "(, )" wrapped arount it,
+	    ;; because byte-compilation will then try to evaluate it while
+	    ;; macro-expanding the uses of emerge-defvar-local, and
+	    ;; emerge-xemacs-p is not defined at that time.
+	    (if emerge-xemacs-p 'permanent-local 'preserved)
+	    t))))
+
+;; Add entries to minor-mode-alist so that emerge modes show correctly
+(defvar emerge-minor-modes-list '((emerge-mode " Emerge")
+				  (emerge-fast-mode " F")
+				  (emerge-edit-mode " E")
+				  (emerge-auto-advance " A")
+				  (emerge-skip-prefers " S")))
+(if (not (assq 'emerge-mode minor-mode-alist))
+    (setq minor-mode-alist (append emerge-minor-modes-list
+				   minor-mode-alist)))
+
+;; We need to define this function so describe-mode can describe Emerge mode.
+(defun emerge-mode ()
+  "Emerge mode is used by the Emerge file-merging package.
+It is entered only through one of the functions:
+	`emerge-files'
+	`emerge-files-with-ancestor'
+	`emerge-buffers'
+	`emerge-buffers-with-ancestor'
+	`emerge-files-command'
+	`emerge-files-with-ancestor-command'
+	`emerge-files-remote'
+	`emerge-files-with-ancestor-remote'
+
+Commands:
+\\{emerge-basic-keymap}
+Commands must be prefixed by \\<emerge-fast-keymap>\\[emerge-basic-keymap] in `edit' mode,
+but can be invoked directly in `fast' mode.")
+
+(defvar emerge-version "5xemacs"
+  "The version of Emerge.")
+
+(defun emerge-version ()
+  "Return string describing the version of Emerge.
+When called interactively, displays the version."
+  (interactive)
+  (if (interactive-p)
+      (message "Emerge version %s" (emerge-version))
+    emerge-version))
+
+;;; Emerge configuration variables
+
+;; Commands that produce difference files
+;; All that can be configured is the name of the programs to execute
+;; (emerge-diff-program and emerge-diff3-program) and the options
+;; to be provided (emerge-diff-options).  The order in which the file names
+;; are given is fixed.
+;; The file names are always expanded (see expand-file-name) before being
+;; passed to diff, thus they need not be invoked under a shell that 
+;; understands `~'.
+;; The code which processes the diff/diff3 output depends on all the
+;; finicky details of their output, including the somewhat strange
+;; way they number lines of a file.
+(defvar emerge-diff-program "diff"
+  "*Name of the program which compares two files.")
+(defvar emerge-diff3-program "diff3"
+  "*Name of the program which compares three files.
+Its arguments are the ancestor file and the two variant files.")
+(defvar emerge-diff-options ""
+  "*Options to pass to `emerge-diff-program' and `emerge-diff3-program'.")
+(defvar emerge-match-diff-line (let ((x "\\([0-9]+\\)\\(\\|,\\([0-9]+\\)\\)"))
+				 (concat "^" x "\\([acd]\\)" x "$"))
+  "*Pattern to match lines produced by diff that describe differences.
+This is as opposed to lines from the source files.")
+(defvar emerge-diff-ok-lines-regexp
+  "^\\([0-9,]+[acd][0-9,]+$\\|[<>] \\|---\\)"
+  "*Regexp that matches normal output lines from `emerge-diff-program'.
+Lines that do not match are assumed to be error messages.")
+(defvar emerge-diff3-ok-lines-regexp
+  "^\\([1-3]:\\|====\\|  \\)"
+  "*Regexp that matches normal output lines from `emerge-diff3-program'.
+Lines that do not match are assumed to be error messages.")
+
+(defvar emerge-rcs-ci-program "ci"
+  "*Name of the program that checks in RCS revisions.")
+(defvar emerge-rcs-co-program "co"
+  "*Name of the program that checks out RCS revisions.")
+
+(defvar emerge-process-local-variables nil
+  "*Non-nil if Emerge should process local-variables lists in merge buffers.
+\(You can explicitly request processing the local-variables
+by executing `(hack-local-variables)'.)")
+(defvar emerge-execute-line-deletions nil
+  "*If non-nil: `emerge-execute-line' makes no output if an input was deleted.
+It concludes that an input version has been deleted when an ancestor entry
+is present, only one A or B entry is present, and an output entry is present.
+If nil: In such circumstances, the A or B file that is present will be
+copied to the designated output file.")
+
+(defvar emerge-before-flag "vvvvvvvvvvvvvvvvvvvv\n"
+  "*Flag placed above the highlighted block of code.  Must end with newline.
+Must be set before Emerge is loaded, or  emerge-new-flags  must be run
+after setting.")
+(defvar emerge-after-flag "^^^^^^^^^^^^^^^^^^^^\n"
+  "*Flag placed below the highlighted block of code.  Must end with newline.
+Must be set before Emerge is loaded, or  emerge-new-flags  must be run
+after setting.")
+
+(defvar emerge-split-horizontally t
+  ;; XEmacs - even when this works, jwz hates it.
+  "*Flag to control whether emerge will split windows horizontally or not.
+Nil means that windows will be split vertically.") 
+
+;; Hook variables
+
+(defvar emerge-startup-hook nil
+  "*Hook to run in the merge buffer after the merge has been set up.")
+(defvar emerge-select-hook nil
+  "*Hook to run after a difference has been selected.
+The variable `n' holds the (internal) number of the difference.")
+(defvar emerge-unselect-hook nil
+  "*Hook to run after a difference has been unselected.
+The variable `n' holds the (internal) number of the difference.")
+
+;; Variables to control the default directories of the arguments to
+;; Emerge commands.
+
+(defvar emerge-default-last-directories nil
+  "*If nil, default dir for filenames in emerge is `default-directory'.
+If non-nil, filenames complete in the directory of the last argument of the
+same type to an `emerge-files...' command.")
+
+(defvar emerge-last-dir-A nil
+  "Last directory for the first file of an `emerge-files...' command.")
+(defvar emerge-last-dir-B nil
+  "Last directory for the second file of an `emerge-files...' command.")
+(defvar emerge-last-dir-ancestor nil
+  "Last directory for the ancestor file of an `emerge-files...' command.")
+(defvar emerge-last-dir-output nil
+  "Last directory for the output file of an `emerge-files...' command.")
+(defvar emerge-last-revision-A nil
+  "Last RCS revision used for first file of an `emerge-revisions...' command.")
+(defvar emerge-last-revision-B nil
+  "Last RCS revision used for second file of an `emerge-revisions...' command.")
+(defvar emerge-last-revision-ancestor nil
+  "Last RCS revision used for ancestor file of an `emerge-revisions...' command.")
+
+(defvar emerge-before-flag-length)
+(defvar emerge-before-flag-lines)
+(defvar emerge-before-flag-match)
+(defvar emerge-after-flag-length)
+(defvar emerge-after-flag-lines)
+(defvar emerge-after-flag-match)
+;;(defvar emerge-diff-buffer)
+;;(defvar emerge-diff-error-buffer)
+(defvar emerge-prefix-argument)
+(defvar emerge-exit-func)		; was just exit-func, but fsf
+					; renamed it and it's not used anywhere
+(defvar emerge-globalized-difference-list)
+(defvar emerge-globalized-number-of-differences)
+
+(defvar A-begin)
+(defvar A-end)
+(defvar B-begin)
+(defvar B-end)
+(defvar merge-begin)
+(defvar merge-end)
+;;(defvar diff)
+(defvar diff-vector)
+(defvar valid-diff)
+
+;; Set up the face to highlight the current difference
+(if emerge-xemacs-p
+    (or (and (find-face 'emerge-highlight-face)
+	     (face-differs-from-default-p 'emerge-highlight-face))
+	(copy-face 'bold-italic 'emerge-highlight-face)))
+
+;;(defvar emerge-mark-with-text (not emerge-xemacs-p))
+;; this doesn't work yet -jwz
+;; and probably never will now that there's ediff --stig
+(defvar emerge-mark-with-text t)
+
+;; These function definitions need to be up here, because they are used
+;; during loading.
+(defun emerge-new-flags ()
+  "Function to be called after `emerge-{before,after}-flag'.
+This is called after these functions are changed to compute values that
+depend on the flags."
+  (setq emerge-before-flag-length (length emerge-before-flag))
+  (setq emerge-before-flag-lines
+	(emerge-count-matches-string emerge-before-flag "\n"))
+  (setq emerge-before-flag-match (regexp-quote emerge-before-flag))
+  (setq emerge-after-flag-length (length emerge-after-flag))
+  (setq emerge-after-flag-lines
+	(emerge-count-matches-string emerge-after-flag "\n"))
+  (setq emerge-after-flag-match (regexp-quote emerge-after-flag)))
+
+(defun emerge-count-matches-string (string regexp)
+  "Return the number of matches in STRING for REGEXP."
+  (let ((i 0)
+	(count 0))
+    (while (string-match regexp string i)
+      (setq count (1+ count))
+      (setq i (match-end 0)))
+    count))
+
+;; Calculate dependent variables
+(emerge-new-flags)
+
+(defvar emerge-min-visible-lines 3
+  "*Number of lines that we want to show above and below the flags when we are
+displaying a difference.")
+
+(defvar emerge-temp-file-prefix
+  (let ((env (or (getenv "TMPDIR")
+		 (getenv "TMP")
+		 (getenv "TEMP")))
+	d)
+    (setq d (if (and env (> (length env) 0))
+		env
+	      "/tmp"))
+    (if (= (aref d (1- (length d))) ?/)
+	(setq d (substring d 0 -1)))
+    (concat d "/emerge"))
+  "*Prefix to put on Emerge temporary file names.
+Do not start with `~/' or `~user-name/'.")
+
+(defvar emerge-temp-file-mode 384	; u=rw only
+  "*Mode for Emerge temporary files.")
+
+(defvar emerge-combine-versions-template
+  "#ifdef NEW\n%b#else /* NEW */\n%a#endif /* NEW */\n"
+  "*Template for `emerge-combine-versions' to combine the two versions.
+The template is inserted as a string, with the following interpolations:
+	%a	the A version of the difference
+	%b	the B version of the difference
+	%%	the character `%'
+Don't forget to end the template with a newline.
+Note that this variable can be made local to a particular merge buffer by
+giving a prefix argument to `emerge-set-combine-versions-template'.")
+
+;; Build keymaps
+
+(defvar emerge-basic-keymap nil
+  "Keymap of Emerge commands.
+Directly available in `fast' mode;
+must be prefixed by \\<emerge-fast-keymap>\\[emerge-basic-keymap] in `edit' mode.")
+
+(defvar emerge-fast-keymap nil
+  "Local keymap used in Emerge `fast' mode.
+Makes Emerge commands directly available.")
+
+(defvar emerge-command-prefix "\C-c"
+  "*Command prefix for Emerge commands in 'edit' mode.
+Must be set before Emerge is loaded.")
+
+;; This function sets up the fixed keymaps.  It is executed when the first
+;; Emerge is done to allow the user maximum time to set up the global keymap.
+(defun emerge-setup-fixed-keymaps ()
+  ;; Set up the basic keymap
+  (setq emerge-basic-keymap (make-keymap))
+  (set-keymap-name emerge-basic-keymap 'emerge-basic-keymap)
+  (suppress-keymap emerge-basic-keymap)	; this sets 0..9 to digit-argument and
+					; - to negative-argument
+  (define-key emerge-basic-keymap "p" 'emerge-previous-difference)
+  (define-key emerge-basic-keymap "n" 'emerge-next-difference)
+  (define-key emerge-basic-keymap "a" 'emerge-select-A)
+  (define-key emerge-basic-keymap "b" 'emerge-select-B)
+  (define-key emerge-basic-keymap "j" 'emerge-jump-to-difference)
+  (define-key emerge-basic-keymap "." 'emerge-find-difference)
+  (define-key emerge-basic-keymap "q" 'emerge-quit)
+  (define-key emerge-basic-keymap "\C-]" 'emerge-abort)
+  (define-key emerge-basic-keymap "f" 'emerge-fast-mode)
+  (define-key emerge-basic-keymap "e" 'emerge-edit-mode)
+  (define-key emerge-basic-keymap "s" nil)
+  (define-key emerge-basic-keymap "sa" 'emerge-auto-advance)
+  (define-key emerge-basic-keymap "ss" 'emerge-skip-prefers)
+  (define-key emerge-basic-keymap "l" 'emerge-recenter)
+  (define-key emerge-basic-keymap "d" nil)
+  (define-key emerge-basic-keymap "da" 'emerge-default-A)
+  (define-key emerge-basic-keymap "db" 'emerge-default-B)
+  (define-key emerge-basic-keymap "c" nil)
+  (define-key emerge-basic-keymap "ca" 'emerge-copy-as-kill-A)
+  (define-key emerge-basic-keymap "cb" 'emerge-copy-as-kill-B)
+  (define-key emerge-basic-keymap "i" nil)
+  (define-key emerge-basic-keymap "ia" 'emerge-insert-A)
+  (define-key emerge-basic-keymap "ib" 'emerge-insert-B)
+  (define-key emerge-basic-keymap "m" 'emerge-mark-difference)
+  (define-key emerge-basic-keymap "v" 'emerge-scroll-up)
+  (define-key emerge-basic-keymap "^" 'emerge-scroll-down)
+  (define-key emerge-basic-keymap "<" 'emerge-scroll-left)
+  (define-key emerge-basic-keymap ">" 'emerge-scroll-right)
+  (define-key emerge-basic-keymap "|" 'emerge-scroll-reset)
+  (define-key emerge-basic-keymap "x" nil)
+  (define-key emerge-basic-keymap "x1" 'emerge-one-line-window)
+  (define-key emerge-basic-keymap "xa" 'emerge-find-difference-A)
+  (define-key emerge-basic-keymap "xb" 'emerge-find-difference-B)
+  (define-key emerge-basic-keymap "xc" 'emerge-combine-versions)
+  (define-key emerge-basic-keymap "xC" 'emerge-combine-versions-register)
+  (define-key emerge-basic-keymap "xd" 'emerge-find-difference)
+  (define-key emerge-basic-keymap "xf" 'emerge-file-names)
+  (define-key emerge-basic-keymap "xj" 'emerge-join-differences)
+  (define-key emerge-basic-keymap "xl" 'emerge-line-numbers)
+  (define-key emerge-basic-keymap "xm" 'emerge-set-merge-mode)
+  (define-key emerge-basic-keymap "xs" 'emerge-split-difference)
+  (define-key emerge-basic-keymap "xt" 'emerge-trim-difference)
+  (define-key emerge-basic-keymap "xx" 'emerge-set-combine-versions-template)
+  ;; Allow emerge-basic-keymap to be referenced indirectly
+  (fset 'emerge-basic-keymap emerge-basic-keymap)
+  ;; Set up the fast mode keymap
+  (setq emerge-fast-keymap (make-sparse-keymap))
+  (set-keymap-parent emerge-fast-keymap emerge-basic-keymap)
+  (set-keymap-name emerge-fast-keymap 'emerge-fast-keymap)
+  ;; Allow prefixed commands to work in fast mode
+  (define-key emerge-fast-keymap emerge-command-prefix 'emerge-basic-keymap)
+  ;; Allow emerge-fast-keymap to be referenced indirectly
+  (fset 'emerge-fast-keymap emerge-fast-keymap)
+  ;; Suppress write-file and save-buffer
+  (substitute-key-definition 'write-file 'emerge-query-write-file
+			     emerge-fast-keymap (current-global-map))
+  (substitute-key-definition 'save-buffer 'emerge-query-save-buffer
+			     emerge-fast-keymap (current-global-map)))
+
+;;fsf   (define-key emerge-basic-keymap [menu-bar] (make-sparse-keymap))
+;;fsf 
+;;fsf   (define-key emerge-fast-keymap [menu-bar options]
+;;fsf     (cons "Options" emerge-options-menu))
+;;fsf   (define-key emerge-fast-keymap [menu-bar merge]
+;;fsf     (cons "Merge" emerge-merge-menu))
+;;fsf   (define-key emerge-fast-keymap [menu-bar move]
+;;fsf     (cons "Move" emerge-move-menu))
+;;fsf 
+;;fsf   (define-key emerge-move-menu [emerge-scroll-reset]
+;;fsf     '("Scroll Reset" . emerge-scroll-reset))
+;;fsf   (define-key emerge-move-menu [emerge-scroll-right]
+;;fsf     '("Scroll Right" . emerge-scroll-right))
+;;fsf   (define-key emerge-move-menu [emerge-scroll-left]
+;;fsf     '("Scroll Left" . emerge-scroll-left))
+;;fsf   (define-key emerge-move-menu [emerge-scroll-down]
+;;fsf     '("Scroll Down" . emerge-scroll-down))
+;;fsf   (define-key emerge-move-menu [emerge-scroll-up]
+;;fsf     '("Scroll Up" . emerge-scroll-up))
+;;fsf   (define-key emerge-move-menu [emerge-recenter]
+;;fsf     '("Recenter" . emerge-recenter))
+;;fsf   (define-key emerge-move-menu [emerge-mark-difference]
+;;fsf     '("Mark Difference" . emerge-mark-difference))
+;;fsf   (define-key emerge-move-menu [emerge-jump-to-difference]
+;;fsf     '("Jump To Difference" . emerge-jump-to-difference))
+;;fsf   (define-key emerge-move-menu [emerge-find-difference]
+;;fsf     '("Find Difference" . emerge-find-difference))
+;;fsf   (define-key emerge-move-menu [emerge-previous-difference]
+;;fsf     '("Previous Difference" . emerge-previous-difference))
+;;fsf   (define-key emerge-move-menu [emerge-next-difference]
+;;fsf     '("Next Difference" . emerge-next-difference))
+;;fsf 
+;;fsf 
+;;fsf   (define-key emerge-options-menu [emerge-one-line-window]
+;;fsf     '("One Line Window" . emerge-one-line-window))
+;;fsf   (define-key emerge-options-menu [emerge-set-merge-mode]
+;;fsf     '("Set Merge Mode" . emerge-set-merge-mode))
+;;fsf   (define-key emerge-options-menu [emerge-set-combine-template]
+;;fsf     '("Set Combine Template..." . emerge-set-combine-template))
+;;fsf   (define-key emerge-options-menu [emerge-default-B]
+;;fsf     '("Default B" . emerge-default-B))
+;;fsf   (define-key emerge-options-menu [emerge-default-A]
+;;fsf     '("Default A" . emerge-default-A))
+;;fsf   (define-key emerge-options-menu [emerge-skip-prefers]
+;;fsf     '("Skip Prefers" . emerge-skip-prefers))
+;;fsf   (define-key emerge-options-menu [emerge-auto-advance]
+;;fsf     '("Auto Advance" . emerge-auto-advance))
+;;fsf   (define-key emerge-options-menu [emerge-edit-mode]
+;;fsf     '("Edit Mode" . emerge-edit-mode))
+;;fsf   (define-key emerge-options-menu [emerge-fast-mode]
+;;fsf     '("Fast Mode" . emerge-fast-mode))
+;;fsf 
+;;fsf   (define-key emerge-merge-menu [emerge-abort] '("Abort" . emerge-abort))
+;;fsf   (define-key emerge-merge-menu [emerge-quit] '("Quit" . emerge-quit))
+;;fsf   (define-key emerge-merge-menu [emerge-split-difference]
+;;fsf     '("Split Difference" . emerge-split-difference))
+;;fsf   (define-key emerge-merge-menu [emerge-join-differences]
+;;fsf     '("Join Differences" . emerge-join-differences))
+;;fsf   (define-key emerge-merge-menu [emerge-trim-difference]
+;;fsf     '("Trim Difference" . emerge-trim-difference))
+;;fsf   (define-key emerge-merge-menu [emerge-combine-versions]
+;;fsf     '("Combine Versions" . emerge-combine-versions))
+;;fsf   (define-key emerge-merge-menu [emerge-copy-as-kill-B]
+;;fsf     '("Copy B as Kill" . emerge-copy-as-kill-B))
+;;fsf   (define-key emerge-merge-menu [emerge-copy-as-kill-A]
+;;fsf     '("Copy A as Kill" . emerge-copy-as-kill-A))
+;;fsf   (define-key emerge-merge-menu [emerge-insert-B]
+;;fsf     '("Insert B" . emerge-insert-B))
+;;fsf   (define-key emerge-merge-menu [emerge-insert-A]
+;;fsf     '("Insert A" . emerge-insert-A))
+;;fsf   (define-key emerge-merge-menu [emerge-select-B]
+;;fsf     '("Select B" . emerge-select-B))
+;;fsf   (define-key emerge-merge-menu [emerge-select-A]
+;;fsf     '("Select A" . emerge-select-A)))
+
+(defvar emerge-menu
+  '(["Buffers ..."			emerge-buffers			t]
+    ["Buffers With Ancestor ..."	emerge-buffers-with-ancestor	t]
+    ["Files ..."			emerge-files			t]
+    ["Files with Ancestor ..."		emerge-files-with-ancestor	t]
+    ["Revisions ..."			emerge-revisions		t]
+    ["Revisions with Ancestor ..."	emerge-revisions-with-ancestor	t]
+    ["Merge Directories ..."		emerge-merge-directories	t])
+  "Menubar entry for using Emerge.")
+
+(defvar emerge-mode-menu
+  '(
+    ["Next Difference"			emerge-next-difference		t]
+    ["Previous Difference"		emerge-previous-difference	t]
+    ("Other Motion"
+     ["Find Difference"			emerge-find-difference		t]
+     ["Jump To Difference"		emerge-jump-to-difference	t]
+     ["Mark Difference"			emerge-mark-difference		t]
+     ["Recenter"			emerge-recenter			t]
+     ["Scroll Up"			emerge-scroll-up		t]
+     ["Scroll Down"			emerge-scroll-down		t]
+     ["Scroll Left"			emerge-scroll-left		t]
+     ["Scroll Right"			emerge-scroll-right		t]
+     ["Scroll Reset"			emerge-scroll-reset		t])
+    "---"
+    ["Select A"				emerge-select-A			t]
+    ["Select B"				emerge-select-B			t]
+    ["Insert A"				emerge-insert-A			t]
+    ["Insert B"				emerge-insert-B			t]
+    ["Copy A as Kill"			emerge-copy-as-kill-A		t]
+    ["Copy B as Kill"			emerge-copy-as-kill-B		t]
+    ("Other Merge"
+      ["Combine Versions"		emerge-combine-versions		t]
+      ["Trim Difference"		emerge-trim-difference		t]
+      ["Join Differences"		emerge-join-differences		t]
+      ["Split Difference"		emerge-split-difference		t])
+    "---"
+    ("Options"
+     ["Fast Mode"			emerge-fast-mode		t]
+     ["Edit Mode"			emerge-edit-mode		t]
+     ["Auto Advance"			emerge-auto-advance		t]
+     ["Skip Prefers"			emerge-skip-prefers		t]
+     ["Default A"			emerge-default-A		t]
+     ["Default B"			emerge-default-B		t]
+     ["Set Combine Template..."		emerge-set-combine-template	t]
+     ["Set Merge Mode"			emerge-set-merge-mode		t]
+     ["One Line Window"			emerge-one-line-window		t])
+    ["Abort"				emerge-abort			t]
+    ["Quit"				emerge-quit			t])
+  "Menubar entry while in Emerge minor mode.")
+
+;; Variables which control each merge.  They are local to the merge buffer.
+
+;; Mode variables
+(emerge-defvar-local emerge-mode nil
+  "Indicator for emerge-mode.")
+(emerge-defvar-local emerge-fast-mode nil
+  "Indicator for emerge-mode fast submode.")
+(emerge-defvar-local emerge-edit-mode nil
+  "Indicator for emerge-mode edit submode.")
+(emerge-defvar-local emerge-A-buffer nil
+  "The buffer in which the A variant is stored.")
+(emerge-defvar-local emerge-B-buffer nil
+  "The buffer in which the B variant is stored.")
+(emerge-defvar-local emerge-merge-buffer nil
+  "The buffer in which the merged file is manipulated.")
+(emerge-defvar-local emerge-ancestor-buffer nil
+  "The buffer in which the ancestor variant is stored,
+or nil if there is none.")
+
+(defconst emerge-saved-variables
+  '((buffer-modified-p set-buffer-modified-p)
+    buffer-read-only
+    buffer-auto-save-file-name)
+  "Variables and properties of a buffer which are saved, modified and restored
+during a merge.")
+(defconst emerge-merging-values '(nil t nil)
+  "Values to be assigned to emerge-saved-variables during a merge.")
+
+(emerge-defvar-local emerge-A-buffer-values nil
+  "Remembers emerge-saved-variables for emerge-A-buffer.")
+(emerge-defvar-local emerge-B-buffer-values nil
+  "Remembers emerge-saved-variables for emerge-B-buffer.")
+
+(emerge-defvar-local emerge-difference-list nil
+  "Vector of differences between the variants, and markers in the buffers to
+show where they are.  Each difference is represented by a vector of seven
+elements.  The first two are markers to the beginning and end of the difference
+section in the A buffer, the second two are markers for the B buffer, the third
+two are markers for the merge buffer, and the last element is the \"state\" of
+that difference in the merge buffer.
+  A section of a buffer is described by two markers, one to the beginning of
+the first line of the section, and one to the beginning of the first line
+after the section.  (If the section is empty, both markers point to the same
+point.)  If the section is part of the selected difference, then the markers
+are moved into the flags, so the user can edit the section without disturbing
+the markers.
+  The \"states\" are:
+	A		the merge buffer currently contains the A variant
+	B		the merge buffer currently contains the B variant
+	default-A	the merge buffer contains the A variant by default,
+			but this difference hasn't been selected yet, so
+			change-default commands can alter it
+	default-B	the merge buffer contains the B variant by default,
+			but this difference hasn't been selected yet, so
+			change-default commands can alter it
+	prefer-A	in a three-file merge, the A variant is the preferred
+			choice
+	prefer-B	in a three-file merge, the B variant is the preferred
+			choice")
+(emerge-defvar-local emerge-current-difference -1
+  "The difference that is currently selected.")
+(emerge-defvar-local emerge-number-of-differences nil
+  "Number of differences found.")
+(emerge-defvar-local emerge-edit-keymap nil
+  "The local keymap for the merge buffer, with the emerge commands defined in
+it.  Used to save the local keymap during fast mode, when the local keymap is
+replaced by emerge-fast-keymap.")
+(emerge-defvar-local emerge-old-keymap nil
+  "The original local keymap for the merge buffer.")
+(emerge-defvar-local emerge-auto-advance nil
+  "*If non-nil, emerge-select-A and emerge-select-B automatically advance to
+the next difference.")
+(emerge-defvar-local emerge-skip-prefers nil
+  "*If non-nil, differences for which there is a preference are automatically
+skipped.")
+(emerge-defvar-local emerge-quit-hook nil
+  "Hooks to run in the merge buffer after the merge has been finished.
+`emerge-prefix-argument' will hold the prefix argument of the `emerge-quit'
+command.
+This is *not* a user option, since Emerge uses it for its own processing.")
+(emerge-defvar-local emerge-output-description nil
+  "Describes output destination of emerge, for `emerge-file-names'.")
+
+;;; Setup functions for two-file mode.
+
+(defun emerge-files-internal (file-A file-B &optional startup-hooks quit-hooks
+				     output-file)
+  (if (not (file-readable-p file-A))
+      (error "File \"%s\" does not exist or is not readable" file-A))
+  (if (not (file-readable-p file-B))
+      (error "File \"%s\" does not exist or is not readable" file-B))
+  (let ((buffer-A (find-file-noselect file-A))
+	(buffer-B (find-file-noselect file-B)))
+    ;; Record the directories of the files
+    (setq emerge-last-dir-A (file-name-directory file-A))
+    (setq emerge-last-dir-B (file-name-directory file-B))
+    (if output-file
+	(setq emerge-last-dir-output (file-name-directory output-file)))
+    ;; Make sure the entire files are seen, and they reflect what is on disk
+    (emerge-eval-in-buffer 
+     buffer-A
+     (widen)
+     (if (emerge-remote-file-p)
+	 (progn
+	   ;; Store in a local file
+	   (setq file-A (emerge-make-temp-file "A"))
+	   (write-region (point-min) (point-max) file-A nil 'no-message)
+	   (setq startup-hooks
+		 (cons (` (lambda () (delete-file (, file-A))))
+		       startup-hooks)))
+       ;; Verify that the file matches the buffer
+       (emerge-verify-file-buffer)))
+    (emerge-eval-in-buffer
+     buffer-B
+     (widen)
+     (if (emerge-remote-file-p)
+	 (progn
+	   ;; Store in a local file
+	   (setq file-B (emerge-make-temp-file "B"))
+	   (write-region (point-min) (point-max) file-B nil 'no-message)
+	   (setq startup-hooks
+		 (cons (` (lambda () (delete-file (, file-B))))
+		       startup-hooks)))
+       ;; Verify that the file matches the buffer
+       (emerge-verify-file-buffer)))
+    (emerge-setup buffer-A file-A buffer-B file-B startup-hooks quit-hooks
+		  output-file)))
+
+;; Start up Emerge on two files
+(defun emerge-setup (buffer-A file-A buffer-B file-B startup-hooks quit-hooks
+			      output-file)
+  (setq file-A (expand-file-name file-A))
+  (setq file-B (expand-file-name file-B))
+  (setq output-file (and output-file (expand-file-name output-file)))
+  (let* ((merge-buffer-name (emerge-unique-buffer-name "*merge" "*"))
+	 ;; create the merge buffer from buffer A, so it inherits buffer A's
+	 ;; default directory, etc.
+	 (merge-buffer (emerge-eval-in-buffer
+			buffer-A
+			(get-buffer-create merge-buffer-name))))
+    (emerge-eval-in-buffer
+     merge-buffer
+     (emerge-copy-modes buffer-A)
+     (setq buffer-read-only nil)
+     (auto-save-mode 1)
+     (setq emerge-mode t)
+     (setq emerge-A-buffer buffer-A)
+     (setq emerge-B-buffer buffer-B)
+     (setq emerge-ancestor-buffer nil)
+     (setq emerge-merge-buffer merge-buffer)
+     (setq emerge-output-description
+	   (if output-file
+	       (concat "Output to file: " output-file)
+	     (concat "Output to buffer: " (buffer-name merge-buffer))))
+     (insert-buffer emerge-A-buffer)
+     (emerge-set-keys)
+     (setq emerge-difference-list (emerge-make-diff-list file-A file-B))
+     (setq emerge-number-of-differences (length emerge-difference-list))
+     (setq emerge-current-difference -1)
+     (setq emerge-quit-hook quit-hooks)
+     (emerge-remember-buffer-characteristics)
+     (emerge-handle-local-variables))
+    (emerge-setup-windows buffer-A buffer-B merge-buffer t)
+    (emerge-eval-in-buffer merge-buffer
+			   (run-hooks 'startup-hooks 'emerge-startup-hook)
+			   (setq buffer-read-only t))))
+
+;; Generate the Emerge difference list between two files
+(defun emerge-make-diff-list (file-A file-B)
+  (let ((diff-buffer (get-buffer-create "*emerge-diff*")))
+    (emerge-eval-in-buffer
+     diff-buffer
+     (erase-buffer)
+     (shell-command
+      (format "%s %s %s %s"
+	      emerge-diff-program emerge-diff-options
+	      (emerge-protect-metachars file-A)
+	      (emerge-protect-metachars file-B))
+      t))
+    (emerge-prepare-error-list emerge-diff-ok-lines-regexp diff-buffer)
+    (emerge-convert-diffs-to-markers
+     emerge-A-buffer emerge-B-buffer emerge-merge-buffer
+     (emerge-extract-diffs diff-buffer))))
+
+(defun emerge-extract-diffs (diff-buffer)
+  (let (list)
+    (emerge-eval-in-buffer
+     diff-buffer
+     (goto-char (point-min))
+     (while (re-search-forward emerge-match-diff-line nil t)
+       (let* ((a-begin (string-to-int (buffer-substring (match-beginning 1)
+							(match-end 1))))
+	      (a-end  (let ((b (match-beginning 3))
+			    (e (match-end 3)))
+			(if b
+			    (string-to-int (buffer-substring b e))
+			  a-begin)))
+	      (diff-type (buffer-substring (match-beginning 4) (match-end 4)))
+	      (b-begin (string-to-int (buffer-substring (match-beginning 5)
+							(match-end 5))))
+	      (b-end (let ((b (match-beginning 7))
+			   (e (match-end 7)))
+		       (if b
+			   (string-to-int (buffer-substring b e))
+			 b-begin))))
+	 ;; fix the beginning and end numbers, because diff is somewhat
+	 ;; strange about how it numbers lines
+	 (if (string-equal diff-type "a")
+	     (progn
+	       (setq b-end (1+ b-end))
+	       (setq a-begin (1+ a-begin))
+	       (setq a-end a-begin))
+	   (if (string-equal diff-type "d")
+	       (progn
+		 (setq a-end (1+ a-end))
+		 (setq b-begin (1+ b-begin))
+		 (setq b-end b-begin))
+	     ;; (string-equal diff-type "c")
+	     (progn
+	       (setq a-end (1+ a-end))
+	       (setq b-end (1+ b-end)))))
+	 (setq list (cons (vector a-begin a-end
+				  b-begin b-end
+				  'default-A)
+			  list)))))
+    (nreverse list)))
+
+;; Set up buffer of diff/diff3 error messages.
+(defun emerge-prepare-error-list (ok-regexp diff-buffer)
+  (setq emerge-diff-error-buffer (get-buffer-create "*emerge-diff-errors*"))
+  (emerge-eval-in-buffer
+   emerge-diff-error-buffer
+   (erase-buffer)
+   (insert-buffer diff-buffer)
+   (delete-matching-lines ok-regexp)))
+
+;;; Top-level and setup functions for three-file mode.
+
+(defun emerge-files-with-ancestor-internal (file-A file-B file-ancestor
+					    &optional startup-hooks quit-hooks
+					    output-file)
+  (if (not (file-readable-p file-A))
+      (error "File \"%s\" does not exist or is not readable" file-A))
+  (if (not (file-readable-p file-B))
+      (error "File \"%s\" does not exist or is not readable" file-B))
+  (if (not (file-readable-p file-ancestor))
+      (error "File \"%s\" does not exist or is not readable" file-ancestor))
+  (let ((buffer-A (find-file-noselect file-A))
+	(buffer-B (find-file-noselect file-B))
+	(buffer-ancestor (find-file-noselect file-ancestor)))
+    ;; Record the directories of the files
+    (setq emerge-last-dir-A (file-name-directory file-A))
+    (setq emerge-last-dir-B (file-name-directory file-B))
+    (setq emerge-last-dir-ancestor (file-name-directory file-ancestor))
+    (if output-file
+	(setq emerge-last-dir-output (file-name-directory output-file)))
+    ;; Make sure the entire files are seen, and they reflect what is on disk
+    (emerge-eval-in-buffer
+     buffer-A
+     (widen)
+     (if (emerge-remote-file-p)
+	 (progn
+	   ;; Store in a local file
+	   (setq file-A (emerge-make-temp-file "A"))
+	   (write-region (point-min) (point-max) file-A nil 'no-message)
+	   (setq startup-hooks
+		 (cons (` (lambda () (delete-file (, file-A))))
+		       startup-hooks)))
+       ;; Verify that the file matches the buffer
+       (emerge-verify-file-buffer)))
+    (emerge-eval-in-buffer
+     buffer-B
+     (widen)
+     (if (emerge-remote-file-p)
+	 (progn
+	   ;; Store in a local file
+	   (setq file-B (emerge-make-temp-file "B"))
+	   (write-region (point-min) (point-max) file-B nil 'no-message)
+	   (setq startup-hooks
+		 (cons (` (lambda () (delete-file (, file-B))))
+		       startup-hooks)))
+       ;; Verify that the file matches the buffer
+       (emerge-verify-file-buffer)))
+    (emerge-eval-in-buffer
+     buffer-ancestor
+     (widen)
+     (if (emerge-remote-file-p)
+	 (progn
+	   ;; Store in a local file
+	   (setq file-ancestor (emerge-make-temp-file "anc"))
+	   (write-region (point-min) (point-max) file-ancestor nil 'no-message)
+	   (setq startup-hooks
+		 (cons (` (lambda () (delete-file (, file-ancestor))))
+		       startup-hooks)))
+       ;; Verify that the file matches the buffer
+       (emerge-verify-file-buffer)))
+    (emerge-setup-with-ancestor buffer-A file-A buffer-B file-B
+				buffer-ancestor file-ancestor
+				startup-hooks quit-hooks output-file)))
+
+;; Start up Emerge on two files with an ancestor
+(defun emerge-setup-with-ancestor (buffer-A file-A buffer-B file-B
+					    buffer-ancestor file-ancestor
+					    &optional startup-hooks quit-hooks
+					    output-file)
+  (setq file-A (expand-file-name file-A))
+  (setq file-B (expand-file-name file-B))
+  (setq file-ancestor (expand-file-name file-ancestor))
+  (setq output-file (and output-file (expand-file-name output-file)))
+  (let* ((merge-buffer-name (emerge-unique-buffer-name "*merge" "*"))
+	 ;; create the merge buffer from buffer A, so it inherits buffer A's
+	 ;; default directory, etc.
+	 (merge-buffer (emerge-eval-in-buffer
+			buffer-A
+			(get-buffer-create merge-buffer-name))))
+    (emerge-eval-in-buffer
+     merge-buffer
+     (emerge-copy-modes buffer-A)
+     (setq buffer-read-only nil)
+     (auto-save-mode 1)
+     (setq emerge-mode t)
+     (setq emerge-A-buffer buffer-A)
+     (setq emerge-B-buffer buffer-B)
+     (setq emerge-ancestor-buffer buffer-ancestor)
+     (setq emerge-merge-buffer merge-buffer)
+     (setq emerge-output-description
+	   (if output-file
+	       (concat "Output to file: " output-file)
+	     (concat "Output to buffer: " (buffer-name merge-buffer))))
+     (insert-buffer emerge-A-buffer)
+     (emerge-set-keys)
+     (setq emerge-difference-list
+	   (emerge-make-diff3-list file-A file-B file-ancestor))
+     (setq emerge-number-of-differences (length emerge-difference-list))
+     (setq emerge-current-difference -1)
+     (setq emerge-quit-hook quit-hooks)
+     (emerge-remember-buffer-characteristics)
+     (emerge-select-prefer-Bs)
+     (emerge-handle-local-variables))
+    (emerge-setup-windows buffer-A buffer-B merge-buffer t)
+    (emerge-eval-in-buffer merge-buffer
+			   (run-hooks 'startup-hooks 'emerge-startup-hook)
+			   (setq buffer-read-only t))))
+
+;; Generate the Emerge difference list between two files with an ancestor
+(defun emerge-make-diff3-list (file-A file-B file-ancestor)
+  (let ((diff-buffer (get-buffer-create "*emerge-diff*")))
+    (emerge-eval-in-buffer
+     diff-buffer
+     (erase-buffer)
+     (shell-command
+      (format "%s %s %s %s %s"
+	      emerge-diff3-program emerge-diff-options
+	      ;; #### - fsf reverses file-ancestor and file-A, why?
+	      (emerge-protect-metachars file-ancestor)
+	      (emerge-protect-metachars file-A)
+	      (emerge-protect-metachars file-B))
+      t))
+    (emerge-prepare-error-list emerge-diff3-ok-lines-regexp diff-buffer)
+    (emerge-convert-diffs-to-markers
+     emerge-A-buffer emerge-B-buffer emerge-merge-buffer
+     (emerge-extract-diffs3 diff-buffer))))
+
+(defun emerge-extract-diffs3 (diff-buffer)
+  (let (list)
+    (emerge-eval-in-buffer
+     diff-buffer
+     (while (re-search-forward "^====\\(.?\\)$" nil t)
+       ;; leave point after matched line
+       (beginning-of-line 2)
+       (let ((agreement (buffer-substring (match-beginning 1) (match-end 1))))
+	 ;; if the A and B files are the same, ignore the difference
+	 (if (not (string-equal agreement "1"))	; this goes with the file-A/ancestor reversal
+	     (setq list
+		   (cons 
+		    (let* ((pos (point))
+                           (group-2 (emerge-get-diff3-group "2"))
+                           (group-3 (progn (goto-char pos)
+                                           (emerge-get-diff3-group "3"))))
+		      (vector (car group-2) (car (cdr group-2))
+			      (car group-3) (car (cdr group-3))
+			      (cond ((string-equal agreement "2") 'prefer-A)
+				    ((string-equal agreement "3") 'prefer-B)
+				    (t 'default-A))))
+		    list))))))
+    (nreverse list)))
+
+(defun emerge-get-diff3-group (file)
+  ;; This save-excursion allows emerge-get-diff3-group to be called for the
+  ;; various groups of lines (1, 2, 3) in any order, and for the lines to
+  ;; appear in any order.  The reason this is necessary is that Gnu diff3
+  ;; can produce the groups in the order 1, 2, 3 or 1, 3, 2.
+  (save-excursion
+    (re-search-forward
+     (concat "^" file ":\\([0-9]+\\)\\(,\\([0-9]+\\)\\)?\\([ac]\\)$"))
+    (beginning-of-line 2)
+    ;; treatment depends on whether it is an "a" group or a "c" group
+    (if (string-equal (buffer-substring (match-beginning 4) (match-end 4)) "c")
+	;; it is a "c" group
+	(if (match-beginning 2)
+	    ;; it has two numbers
+	    (list (string-to-int
+		   (buffer-substring (match-beginning 1) (match-end 1)))
+		  (1+ (string-to-int
+		       (buffer-substring (match-beginning 3) (match-end 3)))))
+	  ;; it has one number
+	  (let ((x (string-to-int
+		    (buffer-substring (match-beginning 1) (match-end 1)))))
+	    (list x (1+ x))))
+      ;; it is an "a" group
+      (let ((x (1+ (string-to-int
+		    (buffer-substring (match-beginning 1) (match-end 1))))))
+	(list x x)))))
+
+;;; Functions to start Emerge on files
+
+;;;###autoload
+(defun emerge-files (arg file-A file-B file-out &optional startup-hooks
+		     quit-hooks)
+  "Run Emerge on two files."
+  (interactive
+   (let (f)
+     (list current-prefix-arg
+	   (setq f (emerge-read-file-name "File A to merge" emerge-last-dir-A
+					  nil nil t))
+	   (emerge-read-file-name "File B to merge" emerge-last-dir-B nil f t)
+	   (and current-prefix-arg
+		(emerge-read-file-name "Output file" emerge-last-dir-output
+				       f f nil)))))
+  (emerge-files-internal
+   file-A file-B startup-hooks
+   (if file-out
+       (cons (` (lambda () (emerge-files-exit (, file-out))))
+	     quit-hooks)
+     quit-hooks)
+   file-out))
+
+;;;###autoload
+(fset 'emerge 'emerge-files)
+
+;;;###autoload
+(defun emerge-files-with-ancestor (arg file-A file-B file-ancestor file-out
+				   &optional startup-hooks quit-hooks)
+  "Run Emerge on two files, giving another file as the ancestor."
+  (interactive
+   (let (f)
+     (list current-prefix-arg
+	   (setq f (emerge-read-file-name "File A to merge" emerge-last-dir-A
+					  nil nil t))
+	   (emerge-read-file-name "File B to merge" emerge-last-dir-B nil f t)
+	   (emerge-read-file-name "Ancestor file" emerge-last-dir-ancestor
+				  nil f t)
+	   (and current-prefix-arg
+		(emerge-read-file-name "Output file" emerge-last-dir-output
+				       f f nil)))))
+  (emerge-files-with-ancestor-internal
+   file-A file-B file-ancestor startup-hooks
+   (if file-out
+       (cons (` (lambda () (emerge-files-exit (, file-out))))
+	     quit-hooks)
+     quit-hooks)
+   file-out))
+
+;; Write the merge buffer out in place of the file the A buffer is visiting.
+(defun emerge-files-exit (file-out)
+  ;; if merge was successful was given, save to disk
+  (if (not emerge-prefix-argument)
+      (emerge-write-and-delete file-out)))
+
+;;; Functions to start Emerge on buffers
+
+;;;###autoload
+(defun emerge-buffers (buffer-A buffer-B &optional startup-hooks quit-hooks)
+  "Run Emerge on two buffers."
+  (interactive "bBuffer A to merge: \nbBuffer B to merge: ")
+  (let ((emerge-file-A (emerge-make-temp-file "A"))
+	(emerge-file-B (emerge-make-temp-file "B")))
+    (emerge-eval-in-buffer
+     buffer-A
+     (write-region (point-min) (point-max) emerge-file-A nil 'no-message))
+    (emerge-eval-in-buffer
+     buffer-B
+     (write-region (point-min) (point-max) emerge-file-B nil 'no-message))
+    (emerge-setup (get-buffer buffer-A) emerge-file-A
+		  (get-buffer buffer-B) emerge-file-B
+		  (cons (` (lambda ()
+			     (delete-file (, emerge-file-A))
+			     (delete-file (, emerge-file-B))))
+			startup-hooks)
+		  quit-hooks
+		  nil)))
+
+;;;###autoload
+(defun emerge-buffers-with-ancestor (buffer-A buffer-B buffer-ancestor
+					      &optional startup-hooks
+					      quit-hooks)
+  "Run Emerge on two buffers, giving another buffer as the ancestor."
+  (interactive
+   "bBuffer A to merge: \nbBuffer B to merge: \nbAncestor buffer: ")
+  (let ((emerge-file-A (emerge-make-temp-file "A"))
+	(emerge-file-B (emerge-make-temp-file "B"))
+	(emerge-file-ancestor (emerge-make-temp-file "anc")))
+    (emerge-eval-in-buffer
+     buffer-A
+     (write-region (point-min) (point-max) emerge-file-A nil 'no-message))
+    (emerge-eval-in-buffer
+     buffer-B
+     (write-region (point-min) (point-max) emerge-file-B nil 'no-message))
+    (emerge-eval-in-buffer
+     buffer-ancestor
+     (write-region (point-min) (point-max) emerge-file-ancestor nil
+		   'no-message))
+    (emerge-setup-with-ancestor (get-buffer buffer-A) emerge-file-A
+				(get-buffer buffer-B) emerge-file-B
+				(get-buffer buffer-ancestor)
+				emerge-file-ancestor
+				(cons (` (lambda ()
+					   (delete-file (, emerge-file-A))
+					   (delete-file (, emerge-file-B))
+					   (delete-file
+					    (, emerge-file-ancestor))))
+				      startup-hooks)
+				quit-hooks
+				nil)))
+
+;;; Functions to start Emerge from the command line
+
+;;;###autoload
+(defun emerge-files-command ()
+  (let ((file-a (nth 0 command-line-args-left))
+	(file-b (nth 1 command-line-args-left))
+	(file-out (nth 2 command-line-args-left)))
+    (setq command-line-args-left (nthcdr 3 command-line-args-left))
+    (emerge-files-internal
+     file-a file-b nil
+     (list (` (lambda () (emerge-command-exit (, file-out))))))))
+
+;;;###autoload
+(defun emerge-files-with-ancestor-command ()
+  (let (file-a file-b file-anc file-out)
+    ;; check for a -a flag, for filemerge compatibility
+    (if (string= (car command-line-args-left) "-a")
+	;; arguments are "-a ancestor file-a file-b file-out"
+	(progn
+	  (setq file-a (nth 2 command-line-args-left))
+	  (setq file-b (nth 3 command-line-args-left))
+	  (setq file-anc (nth 1 command-line-args-left))
+	  (setq file-out (nth 4 command-line-args-left))
+	  (setq command-line-args-left (nthcdr 5 command-line-args-left)))
+      ;; arguments are "file-a file-b ancestor file-out"
+      (setq file-a (nth 0 command-line-args-left))
+      (setq file-b (nth 1 command-line-args-left))
+      (setq file-anc (nth 2 command-line-args-left))
+      (setq file-out (nth 3 command-line-args-left))
+      (setq command-line-args-left (nthcdr 4 command-line-args-left)))
+    (emerge-files-with-ancestor-internal
+     file-a file-b file-anc nil
+     (list (` (lambda () (emerge-command-exit (, file-out))))))))
+      
+(defun emerge-command-exit (file-out)
+  (emerge-write-and-delete file-out)
+  (kill-emacs (if emerge-prefix-argument 1 0)))
+
+;;; Functions to start Emerge via remote request
+
+;;;###autoload
+(defun emerge-files-remote (file-a file-b file-out)
+  (emerge-files-internal
+   file-a file-b nil
+   (list (` (lambda () (emerge-remote-exit (, file-out) '(, emerge-exit-func)))))
+   file-out)
+  (throw 'client-wait nil))
+
+;;;###autoload
+(defun emerge-files-with-ancestor-remote (file-a file-b file-anc file-out)
+  (emerge-files-with-ancestor-internal
+   file-a file-b file-anc nil
+   (list (` (lambda () (emerge-remote-exit (, file-out) '(, emerge-exit-func)))))
+   file-out)
+  (throw 'client-wait nil))
+
+(defun emerge-remote-exit (file-out emerge-exit-func)
+  (emerge-write-and-delete file-out)
+  (kill-buffer emerge-merge-buffer)
+  (funcall emerge-exit-func (if emerge-prefix-argument 1 0)))
+
+;;; Functions to start Emerge on RCS versions
+
+;;;###autoload
+(defun emerge-revisions (arg file revision-A revision-B
+			 &optional startup-hooks quit-hooks)
+  "Emerge two RCS revisions of a file."
+  (interactive
+   (list current-prefix-arg
+	 (read-file-name "File to merge: " nil nil 'confirm)
+	 (read-string "Revision A to merge: " emerge-last-revision-A)
+	 (read-string "Revision B to merge: " emerge-last-revision-B)))
+  (setq emerge-last-revision-A revision-A
+	emerge-last-revision-B revision-B)
+  (emerge-revisions-internal
+   file revision-A revision-B startup-hooks
+   (if arg
+       (cons (` (lambda ()
+		  (shell-command
+		   (, (format "%s %s" emerge-rcs-ci-program file)))))
+	     quit-hooks)
+     quit-hooks)))
+
+;;;###autoload
+(defun emerge-revisions-with-ancestor (arg file revision-A
+					   revision-B ancestor
+					   &optional
+					   startup-hooks quit-hooks)
+  "Emerge two RCS revisions of a file, with another revision as ancestor."
+  (interactive
+   (list current-prefix-arg
+	 (read-file-name "File to merge: " nil nil 'confirm)
+	 (read-string "Revision A to merge: " emerge-last-revision-A)
+	 (read-string "Revision B to merge: " emerge-last-revision-B)
+	 (read-string "Ancestor: " emerge-last-revision-ancestor)))
+  (setq emerge-last-revision-A revision-A
+	emerge-last-revision-B revision-B
+	emerge-last-revision-ancestor ancestor)
+  (emerge-revision-with-ancestor-internal
+   file revision-A revision-B ancestor startup-hooks
+   (if arg
+       (let ((cmd ))
+	 (cons (` (lambda ()
+		    (shell-command
+		     (, (format "%s %s" emerge-rcs-ci-program file)))))
+	       quit-hooks))
+     quit-hooks)))
+
+(defun emerge-revisions-internal (file revision-A revision-B &optional
+				      startup-hooks quit-hooks output-file)
+  (let ((buffer-A (get-buffer-create (format "%s,%s" file revision-A)))
+	(buffer-B (get-buffer-create (format "%s,%s" file revision-B)))
+	(emerge-file-A (emerge-make-temp-file "A"))
+	(emerge-file-B (emerge-make-temp-file "B")))
+    ;; Get the revisions into buffers
+    (emerge-eval-in-buffer
+     buffer-A
+     (erase-buffer)
+     (shell-command
+      (format "%s -q -p%s %s" emerge-rcs-co-program revision-A file)
+      t)
+     (write-region (point-min) (point-max) emerge-file-A nil 'no-message)
+     (set-buffer-modified-p nil))
+    (emerge-eval-in-buffer
+     buffer-B
+     (erase-buffer)
+     (shell-command
+      (format "%s -q -p%s %s" emerge-rcs-co-program revision-B file)
+      t)
+     (write-region (point-min) (point-max) emerge-file-B nil 'no-message)
+     (set-buffer-modified-p nil))
+    ;; Do the merge
+    (emerge-setup buffer-A emerge-file-A
+		  buffer-B emerge-file-B
+		  (cons (` (lambda ()
+			     (delete-file (, emerge-file-A))
+			     (delete-file (, emerge-file-B))))
+			startup-hooks)
+		  (cons (` (lambda () (emerge-files-exit (, file))))
+			quit-hooks)
+		  nil)))
+
+(defun emerge-revision-with-ancestor-internal (file revision-A revision-B
+						    ancestor
+						    &optional startup-hooks
+						    quit-hooks output-file)
+  (let ((buffer-A (get-buffer-create (format "%s,%s" file revision-A)))
+	(buffer-B (get-buffer-create (format "%s,%s" file revision-B)))
+	(buffer-ancestor (get-buffer-create (format "%s,%s" file ancestor)))
+	(emerge-file-A (emerge-make-temp-file "A"))
+	(emerge-file-B (emerge-make-temp-file "B"))
+	(emerge-ancestor (emerge-make-temp-file "ancestor")))
+    ;; Get the revisions into buffers
+    (emerge-eval-in-buffer
+     buffer-A
+     (erase-buffer)
+     (shell-command
+      (format "%s -q -p%s %s" emerge-rcs-co-program
+	      revision-A file)
+      t)
+     (write-region (point-min) (point-max) emerge-file-A nil 'no-message)
+     (set-buffer-modified-p nil))
+    (emerge-eval-in-buffer
+     buffer-B
+     (erase-buffer)
+     (shell-command
+      (format "%s -q -p%s %s" emerge-rcs-co-program revision-B file)
+      t)
+     (write-region (point-min) (point-max) emerge-file-B nil 'no-message)
+     (set-buffer-modified-p nil))
+    (emerge-eval-in-buffer
+     buffer-ancestor
+     (erase-buffer)
+     (shell-command
+      (format "%s -q -p%s %s" emerge-rcs-co-program ancestor file)
+      t)
+     (write-region (point-min) (point-max) emerge-ancestor nil 'no-message)
+     (set-buffer-modified-p nil))
+    ;; Do the merge
+    (emerge-setup-with-ancestor
+     buffer-A emerge-file-A buffer-B emerge-file-B
+     buffer-ancestor emerge-ancestor
+     (cons (` (lambda ()
+		(delete-file (, emerge-file-A))
+		(delete-file (, emerge-file-B))
+		(delete-file (, emerge-ancestor))))
+	   startup-hooks)
+     (cons (` (lambda () (emerge-files-exit (, file))))
+	   quit-hooks)
+     output-file)))
+
+;;; Function to start Emerge based on a line in a file
+
+(defun emerge-execute-line ()
+  "Run Emerge using files named in current text line.
+Looks in that line for whitespace-separated entries of these forms:
+	a=file1
+	b=file2
+	ancestor=file3
+	output=file4
+to specify the files to use in Emerge.
+
+In addition, if only one of `a=file' or `b=file' is present,
+and `output=file' is present:
+If `emerge-execute-line-deletions' is non-nil and `ancestor=file'
+is present, it is assumed that the file in question has been deleted,
+and it is not copied to the output file.
+Otherwise, the A or B file present is copied to the output file."
+  (interactive)
+  (let (file-A file-B file-ancestor file-out
+	       (case-fold-search t))
+    ;; Stop if at end of buffer (even though we might be in a line, if
+    ;; the line does not end with newline)
+    (if (eobp)
+	(error "At end of buffer"))
+    ;; Go to the beginning of the line
+    (beginning-of-line)
+    ;; Skip any initial whitespace
+    (if (looking-at "[ \t]*")
+	(goto-char (match-end 0)))
+    ;; Process the entire line
+    (while (not (eolp))
+      ;; Get the next entry
+      (if (looking-at "\\([a-z]+\\)=\\([^ \t\n]+\\)[ \t]*")
+	  ;; Break apart the tab (before =) and the filename (after =)
+	  (let ((tag (downcase
+		      (buffer-substring (match-beginning 1) (match-end 1))))
+		(file (buffer-substring (match-beginning 2) (match-end 2))))
+	    ;; Move point after the entry
+	    (goto-char (match-end 0))
+	    ;; Store the filename in the right variable
+	    (cond
+	     ((string-equal tag "a")
+	      (if file-A
+		  (error "This line has two `A' entries"))
+	      (setq file-A file))
+	     ((string-equal tag "b")
+	      (if file-B
+		  (error "This line has two `B' entries"))
+	      (setq file-B file))
+	     ((or (string-equal tag "anc") (string-equal tag "ancestor"))
+	      (if file-ancestor
+		  (error "This line has two `ancestor' entries"))
+	      (setq file-ancestor file))
+	     ((or (string-equal tag "out") (string-equal tag "output"))
+	      (if file-out
+		  (error "This line has two `output' entries"))
+	      (setq file-out file))
+	     (t
+	      (error "Unrecognized entry"))))
+	;; If the match on the entry pattern failed
+	(error "Unparsable entry")))
+    ;; Make sure that file-A and file-B are present
+    (if (not (or (and file-A file-B) file-out))
+	(error "Must have both `A' and `B' entries"))
+    (if (not (or file-A file-B))
+	(error "Must have `A' or `B' entry"))
+    ;; Go to the beginning of the next line, so next execution will use
+    ;; next line in buffer.
+    (beginning-of-line 2)
+    ;; Execute the correct command
+    (cond
+     ;; Merge of two files with ancestor
+     ((and file-A file-B file-ancestor)
+      (message "Merging %s and %s..." file-A file-B)
+      (emerge-files-with-ancestor (not (not file-out)) file-A file-B
+				  file-ancestor file-out
+				  nil
+				  ;; When done, return to this buffer.
+				  (list
+				   (` (lambda ()
+					(switch-to-buffer (, (current-buffer)))
+					(message "Merge done."))))))
+     ;; Merge of two files without ancestor
+     ((and file-A file-B)
+      (message "Merging %s and %s..." file-A file-B)
+      (emerge-files (not (not file-out)) file-A file-B file-out
+		    nil
+		    ;; When done, return to this buffer.
+		    (list 
+		     (` (lambda ()
+			  (switch-to-buffer (, (current-buffer)))
+			  (message "Merge done."))))))
+     ;; There is an output file (or there would have been an error above),
+     ;; but only one input file.
+     ;; The file appears to have been deleted in one version; do nothing.
+     ((and file-ancestor emerge-execute-line-deletions)
+      (message "No action."))
+     ;; The file should be copied from the version that contains it
+     (t (let ((input-file (or file-A file-B)))
+	  (message "Copying...")
+	  (copy-file input-file file-out)
+	  (message "%s copied to %s." input-file file-out))))))
+
+;;; Sample function for creating information for emerge-execute-line
+
+(defvar emerge-merge-directories-filename-regexp "[^.]"
+  "Regexp describing files to be processed by `emerge-merge-directories'.")
+
+;;;###autoload
+(defun emerge-merge-directories (a-dir b-dir ancestor-dir output-dir)
+  (interactive 
+   (list
+    (read-file-name "A directory: " nil nil 'confirm)
+    (read-file-name "B directory: " nil nil 'confirm)
+    (read-file-name "Ancestor directory (null for none): " nil nil 'confirm)
+    (read-file-name "Output directory (null for none): " nil nil 'confirm)))
+  ;; Check that we're not on a line
+  (if (not (and (bolp) (eolp)))
+      (error "There is text on this line"))
+  ;; Turn null strings into nil to indicate directories not used.
+  (if (and ancestor-dir (string-equal ancestor-dir ""))
+      (setq ancestor-dir nil))
+  (if (and output-dir (string-equal output-dir ""))
+      (setq output-dir nil))
+  ;; Canonicalize the directory names
+  (setq a-dir (expand-file-name a-dir))
+  (if (not (string-equal (substring a-dir -1) "/"))
+      (setq a-dir (concat a-dir "/")))
+  (setq b-dir (expand-file-name b-dir))
+  (if (not (string-equal (substring b-dir -1) "/"))
+      (setq b-dir (concat b-dir "/")))
+  (if ancestor-dir
+      (progn
+	(setq ancestor-dir (expand-file-name ancestor-dir))
+	(if (not (string-equal (substring ancestor-dir -1) "/"))
+	    (setq ancestor-dir (concat ancestor-dir "/")))))
+  (if output-dir
+      (progn
+	(setq output-dir (expand-file-name output-dir))
+	(if (not (string-equal (substring output-dir -1) "/"))
+	    (setq output-dir (concat output-dir "/")))))
+  ;; Set the mark to where we start
+  (push-mark)
+  ;; Find out what files are in the directories.
+  (let* ((a-dir-files
+	  (directory-files a-dir nil emerge-merge-directories-filename-regexp))
+	 (b-dir-files
+	  (directory-files b-dir nil emerge-merge-directories-filename-regexp))
+	 (ancestor-dir-files
+	  (and ancestor-dir
+	       (directory-files ancestor-dir nil
+				emerge-merge-directories-filename-regexp)))
+	 (all-files (sort (nconc (copy-sequence a-dir-files)
+				 (copy-sequence b-dir-files)
+				 (copy-sequence ancestor-dir-files))
+			  (function string-lessp))))
+    ;; Remove duplicates from all-files.
+    (let ((p all-files))
+      (while p
+	(if (and (cdr p) (string-equal (car p) (car (cdr p))))
+	    (setcdr p (cdr (cdr p)))
+	  (setq p (cdr p)))))
+    ;; Generate the control lines for the various files.
+    (while all-files
+      (let ((f (car all-files)))
+	(setq all-files (cdr all-files))
+	(if (and a-dir-files (string-equal (car a-dir-files) f))
+	    (progn
+	      (insert "A=" a-dir f "\t")
+	      (setq a-dir-files (cdr a-dir-files))))
+	(if (and b-dir-files (string-equal (car b-dir-files) f))
+	    (progn
+	      (insert "B=" b-dir f "\t")
+	      (setq b-dir-files (cdr b-dir-files))))
+	(if (and ancestor-dir-files (string-equal (car ancestor-dir-files) f))
+	    (progn
+	      (insert "ancestor=" ancestor-dir f "\t")
+	      (setq ancestor-dir-files (cdr ancestor-dir-files))))
+	(if output-dir
+	    (insert "output=" output-dir f "\t"))
+	(backward-delete-char 1)
+	(insert "\n")))))
+
+;;; Common setup routines
+
+;; Set up the window configuration.  If POS is given, set the points to
+;; the beginnings of the buffers.
+(defun emerge-setup-windows (buffer-A buffer-B merge-buffer &optional pos)
+  ;; Make sure we are not in the minibuffer window when we try to delete
+  ;; all other windows.
+  (if (eq (selected-window) (minibuffer-window))
+      (other-window 1))
+  (delete-other-windows)
+  (switch-to-buffer merge-buffer)
+  (emerge-refresh-mode-line)
+  ;; in v18, split-window and split-window-vertically were the same,
+  ;; but in v19, split-window-vertically might select the other window.
+  ;;  (split-window-vertically)
+  (split-window)
+  (if emerge-split-horizontally
+      (split-window-horizontally)
+    (split-window))
+  (switch-to-buffer buffer-A)
+  (if pos
+      (goto-char (point-min)))
+  (other-window 1)
+  (switch-to-buffer buffer-B)
+  (if pos
+      (goto-char (point-min)))
+  (other-window 1)
+  (if pos
+      (goto-char (point-min)))
+  ;; If diff/diff3 reports errors, display them rather than the merge buffer.
+  (if (/= 0 (emerge-eval-in-buffer emerge-diff-error-buffer (buffer-size)))
+      (progn
+	(ding)
+	(message "Errors found in diff/diff3 output.  Merge buffer is %s."
+		 (buffer-name emerge-merge-buffer))
+	(switch-to-buffer emerge-diff-error-buffer))))
+
+;; Set up the keymap in the merge buffer
+(defun emerge-set-keys ()
+  ;; Set up fixed keymaps if necessary
+  (if (not emerge-basic-keymap)
+      (emerge-setup-fixed-keymaps))
+  ;; Save the old local map
+  (setq emerge-old-keymap (current-local-map))
+  ;; Construct the edit keymap
+  (setq emerge-edit-keymap (if emerge-old-keymap
+			       (copy-keymap emerge-old-keymap)
+			     (make-sparse-keymap)))
+  ;; Install the Emerge commands
+  (emerge-force-define-key emerge-edit-keymap emerge-command-prefix
+			   'emerge-basic-keymap)
+  ;;fsf   (define-key emerge-edit-keymap [menu-bar] (make-sparse-keymap))
+  ;;fsf 
+  ;;fsf   ;; Create the additional menu bar items.
+  ;;fsf   (define-key emerge-edit-keymap [menu-bar options]
+  ;;fsf     (cons "Options" emerge-options-menu))
+  ;;fsf   (define-key emerge-edit-keymap [menu-bar merge]
+  ;;fsf     (cons "Merge" emerge-merge-menu))
+  ;;fsf   (define-key emerge-edit-keymap [menu-bar move]
+  ;;fsf     (cons "Move" emerge-move-menu))
+
+  ;; Suppress write-file and save-buffer
+  (substitute-key-definition 'write-file 'emerge-query-write-file
+			     emerge-edit-keymap (current-global-map))
+  (substitute-key-definition 'save-buffer 'emerge-query-save-buffer
+			     emerge-edit-keymap (current-global-map))
+  (substitute-key-definition 'write-file 'emerge-query-write-file
+			     emerge-edit-keymap (current-global-map))
+  (substitute-key-definition 'save-buffer 'emerge-query-save-buffer
+			     emerge-edit-keymap (current-global-map))
+  (use-local-map emerge-fast-keymap)
+  (make-local-variable 'current-menubar)
+  (add-menu nil "Emerge" emerge-mode-menu)
+  (setq emerge-edit-mode nil)
+  (setq emerge-fast-mode t))
+
+(defun emerge-remember-buffer-characteristics ()
+  "Record certain properties of the buffers being merged.
+Must be called in the merge buffer.  Remembers read-only, modified,
+auto-save, and saves them in buffer local variables.  Sets the buffers
+read-only and turns off `auto-save-mode'.
+These characteristics are restored by `emerge-restore-buffer-characteristics'."
+  ;; force auto-save, because we will turn off auto-saving in buffers for the
+  ;; duration
+  (do-auto-save)
+  ;; remember and alter buffer characteristics
+  (setq emerge-A-buffer-values
+	(emerge-eval-in-buffer
+	 emerge-A-buffer
+	 (prog1
+	     (emerge-save-variables emerge-saved-variables)
+	   (emerge-restore-variables emerge-saved-variables
+				     emerge-merging-values))))
+  (setq emerge-B-buffer-values
+	(emerge-eval-in-buffer
+	 emerge-B-buffer
+	 (prog1
+	     (emerge-save-variables emerge-saved-variables)
+	   (emerge-restore-variables emerge-saved-variables
+				     emerge-merging-values)))))
+
+(defun emerge-restore-buffer-characteristics ()
+  "Restores characteristics saved by `emerge-remember-buffer-characteristics'."
+  (let ((A-values emerge-A-buffer-values)
+	(B-values emerge-B-buffer-values))
+    (emerge-eval-in-buffer emerge-A-buffer
+			   (emerge-restore-variables emerge-saved-variables
+						     A-values))
+    (emerge-eval-in-buffer emerge-B-buffer
+			   (emerge-restore-variables emerge-saved-variables
+						     B-values))))
+;; Move to line DESIRED-LINE assuming we are at line CURRENT-LINE.
+;; Return DESIRED-LINE.
+(defun emerge-goto-line (desired-line current-line)
+  (forward-line (- desired-line current-line))
+  desired-line)
+
+(defun emerge-convert-diffs-to-markers (A-buffer
+					B-buffer
+					merge-buffer
+					lineno-list)
+  (let* (marker-list
+	 (A-point-min (emerge-eval-in-buffer A-buffer (point-min)))
+	 (offset (1- A-point-min))
+	 (B-point-min (emerge-eval-in-buffer B-buffer (point-min)))
+	 ;; Record current line number in each buffer
+	 ;; so we don't have to count from the beginning.
+	 (a-line 1)
+	 (b-line 1))
+    (emerge-eval-in-buffer A-buffer (goto-char (point-min)))
+    (emerge-eval-in-buffer B-buffer (goto-char (point-min)))
+    (while lineno-list
+      (let* ((list-element (car lineno-list))
+	     a-begin-marker
+	     a-end-marker
+	     b-begin-marker
+	     b-end-marker
+	     merge-begin-marker
+	     merge-end-marker
+	     (a-begin (aref list-element 0))
+	     (a-end (aref list-element 1))
+	     (b-begin (aref list-element 2))
+	     (b-end (aref list-element 3))
+	     (state (aref list-element 4)))
+	;; place markers at the appropriate places in the buffers
+	(emerge-eval-in-buffer
+	 A-buffer
+	 (setq a-line (emerge-goto-line a-begin a-line))
+	 (setq a-begin-marker (point-marker))
+	 (setq a-line (emerge-goto-line a-end a-line))
+	 (setq a-end-marker (point-marker)))
+	(emerge-eval-in-buffer
+	 B-buffer
+	 (setq b-line (emerge-goto-line b-begin b-line))
+	 (setq b-begin-marker (point-marker))
+	 (setq b-line (emerge-goto-line b-end b-line))
+	 (setq b-end-marker (point-marker)))
+	(setq merge-begin-marker (set-marker
+				  (make-marker)
+				  (- (marker-position a-begin-marker)
+				     offset)
+				  merge-buffer))
+	(setq merge-end-marker (set-marker
+				(make-marker)
+				(- (marker-position a-end-marker)
+				   offset)
+				merge-buffer))
+	;; record all the markers for this difference
+	(setq marker-list (cons (vector a-begin-marker a-end-marker
+					b-begin-marker b-end-marker
+					merge-begin-marker merge-end-marker
+					state)
+				marker-list)))
+      (setq lineno-list (cdr lineno-list)))
+    ;; convert the list of difference information into a vector for
+    ;; fast access
+    (setq emerge-difference-list (apply 'vector (nreverse marker-list)))))
+
+;; If we have an ancestor, select all B variants that we prefer 
+(defun emerge-select-prefer-Bs ()
+  (let ((n 0))
+    (while (< n emerge-number-of-differences)
+      (if (eq (aref (aref emerge-difference-list n) 6) 'prefer-B)
+	  (progn
+	    (emerge-unselect-and-select-difference n t)
+	    (emerge-select-B)
+	    (aset (aref emerge-difference-list n) 6 'prefer-B)))
+      (setq n (1+ n))))
+  (emerge-unselect-and-select-difference -1))
+
+;; Process the local-variables list at the end of the merged file, if
+;; requested.
+(defun emerge-handle-local-variables ()
+  (if emerge-process-local-variables
+      (condition-case err
+	  (hack-local-variables t)
+	(error (message "Local-variables error in merge buffer: %s"
+			(prin1-to-string err))))))
+
+;;; Common exit routines
+
+(defun emerge-write-and-delete (file-out)
+  ;; clear screen format
+  (delete-other-windows)
+  ;; delete A, B, and ancestor buffers, if they haven't been changed
+  (if (not (buffer-modified-p emerge-A-buffer))
+      (kill-buffer emerge-A-buffer))
+  (if (not (buffer-modified-p emerge-B-buffer))
+      (kill-buffer emerge-B-buffer))
+  (if (and emerge-ancestor-buffer
+	   (not (buffer-modified-p emerge-ancestor-buffer)))
+      (kill-buffer emerge-ancestor-buffer))
+  ;; Write merge buffer to file
+  (and file-out
+       (write-file file-out)))
+
+;;; Commands
+
+(defun emerge-recenter (&optional arg)
+  "Bring the highlighted region of all three merge buffers into view.
+This brings the buffers into view if they are in windows.
+With an argument, reestablish the default three-window display."
+  (interactive "P")
+  ;; If there is an argument, rebuild the window structure
+  (if arg
+      (emerge-setup-windows emerge-A-buffer emerge-B-buffer
+			    emerge-merge-buffer))
+  ;; Redisplay whatever buffers are showing, if there is a selected difference
+  (if (and (>= emerge-current-difference 0)
+	   (< emerge-current-difference emerge-number-of-differences))
+      (let* ((merge-buffer emerge-merge-buffer)
+	     (buffer-A emerge-A-buffer)
+	     (buffer-B emerge-B-buffer)
+	     (window-A (get-buffer-window buffer-A 'visible))
+	     (window-B (get-buffer-window buffer-B 'visible))
+	     (merge-window (get-buffer-window merge-buffer))
+	     (diff-vector
+	      (aref emerge-difference-list emerge-current-difference)))
+	;; note that emerge-{before,after}-flag-length are meaningless
+	;; when (not emerge-mark-with-text).  -jwz.
+	(if window-A (progn
+		       (select-window window-A)
+		       (emerge-position-region
+			(- (aref diff-vector 0)
+			   (if emerge-mark-with-text
+			       (1- emerge-before-flag-length)
+			     0))
+			(+ (aref diff-vector 1)
+			   (if emerge-mark-with-text
+			       (1- emerge-after-flag-length)
+			     0))
+			(1+ (aref diff-vector 0)))))
+	(if window-B (progn
+		       (select-window window-B)
+		       (emerge-position-region
+			(- (aref diff-vector 2)
+			   (if emerge-mark-with-text
+			       (1- emerge-before-flag-length)
+			     0))
+			(+ (aref diff-vector 3)
+			   (if emerge-mark-with-text
+			       (1- emerge-after-flag-length)
+			     0))
+			(1+ (aref diff-vector 2)))))
+	(if merge-window (progn
+			   (select-window merge-window)
+			   (emerge-position-region
+			    (- (aref diff-vector 4)
+			       (if emerge-mark-with-text
+				   (1- emerge-before-flag-length)
+				 0))
+			    (+ (aref diff-vector 5)
+			       (if emerge-mark-with-text
+				   (1- emerge-after-flag-length)
+				 0))
+			    (1+ (aref diff-vector 4))))))))
+
+;;; Window scrolling operations
+;; These operations are designed to scroll all three windows the same amount,
+;; so as to keep the text in them aligned.
+
+;; Perform some operation on all three windows (if they are showing).
+;; Catches all errors on the operation in the A and B windows, but not
+;; in the merge window.  Usually, errors come from scrolling off the
+;; beginning or end of the buffer, and this gives a nice error message:
+;; End of buffer is reported in the merge buffer, but if the scroll was
+;; possible in the A or B windows, it is performed there before the error
+;; is reported.
+(defun emerge-operate-on-windows (operation arg)
+  (let* ((merge-buffer emerge-merge-buffer)
+	 (buffer-A emerge-A-buffer)
+	 (buffer-B emerge-B-buffer)
+	 (window-A (get-buffer-window buffer-A 'visible))
+	 (window-B (get-buffer-window buffer-B 'visible))
+	 (merge-window (get-buffer-window merge-buffer)))
+    (if window-A (progn
+		   (select-window window-A)
+		   (condition-case nil
+		       (funcall operation arg)
+		     (error))))
+    (if window-B (progn
+		   (select-window window-B)
+		   (condition-case nil
+		       (funcall operation arg)
+		     (error))))
+    (if merge-window (progn
+		       (select-window merge-window)
+		       (funcall operation arg)))))
+
+(defun emerge-scroll-up (&optional arg)
+  "Scroll up all three merge buffers, if they are in windows.
+With argument N, scroll N lines; otherwise scroll by nearly
+the height of the merge window.
+`C-u -' alone as argument scrolls half the height of the merge window."
+  (interactive "P")
+  (emerge-operate-on-windows
+   'scroll-up 
+   ;; calculate argument to scroll-up
+   ;; if there is an explicit argument
+   (if (and arg (not (equal arg '-)))
+       ;; use it
+       (prefix-numeric-value arg)
+     ;; if not, see if we can determine a default amount (the window height)
+     (let ((merge-window (get-buffer-window emerge-merge-buffer)))
+       (if (null merge-window)
+	   ;; no window, use nil
+	   nil
+	 (let ((default-amount
+		 (- (window-height merge-window) 1 next-screen-context-lines)))
+	   ;; the window was found
+	   (if arg
+	       ;; C-u as argument means half of default amount
+	       (/ default-amount 2)
+	     ;; no argument means default amount
+	     default-amount)))))))
+
+(defun emerge-scroll-down (&optional arg)
+  "Scroll down all three merge buffers, if they are in windows.
+With argument N, scroll N lines; otherwise scroll by nearly
+the height of the merge window.
+`C-u -' alone as argument scrolls half the height of the merge window."
+  (interactive "P")
+  (emerge-operate-on-windows
+   'scroll-down
+   ;; calculate argument to scroll-down
+   ;; if there is an explicit argument
+   (if (and arg (not (equal arg '-)))
+       ;; use it
+       (prefix-numeric-value arg)
+     ;; if not, see if we can determine a default amount (the window height)
+     (let ((merge-window (get-buffer-window emerge-merge-buffer)))
+       (if (null merge-window)
+	   ;; no window, use nil
+	   nil
+	 (let ((default-amount
+		 (- (window-height merge-window) 1 next-screen-context-lines)))
+	   ;; the window was found
+	   (if arg
+	       ;; C-u as argument means half of default amount
+	       (/ default-amount 2)
+	     ;; no argument means default amount
+	     default-amount)))))))
+
+(defun emerge-scroll-left (&optional arg)
+  "Scroll left all three merge buffers, if they are in windows.
+If an argument is given, that is how many columns are scrolled, else nearly
+the width of the A and B windows.  `C-u -' alone as argument scrolls half the
+width of the A and B windows."
+  (interactive "P")
+  (emerge-operate-on-windows
+   'scroll-left
+   ;; calculate argument to scroll-left
+   ;; if there is an explicit argument
+   (if (and arg (not (equal arg '-)))
+       ;; use it
+       (prefix-numeric-value arg)
+     ;; if not, see if we can determine a default amount
+     ;; (half the window width)
+     (let ((merge-window (get-buffer-window emerge-merge-buffer)))
+       (if (null merge-window)
+	   ;; no window, use nil
+	   nil
+	 (let ((default-amount
+		 (- (/ (window-width merge-window) 2) 3)))
+	   ;; the window was found
+	   (if arg
+	       ;; C-u as argument means half of default amount
+	       (/ default-amount 2)
+	     ;; no argument means default amount
+	     default-amount)))))))
+
+(defun emerge-scroll-right (&optional arg)
+  "Scroll right all three merge buffers, if they are in windows.
+If an argument is given, that is how many columns are scrolled, else nearly
+the width of the A and B windows.  `C-u -' alone as argument scrolls half the
+width of the A and B windows."
+  (interactive "P")
+  (emerge-operate-on-windows
+   'scroll-right
+   ;; calculate argument to scroll-right
+   ;; if there is an explicit argument
+   (if (and arg (not (equal arg '-)))
+       ;; use it
+       (prefix-numeric-value arg)
+     ;; if not, see if we can determine a default amount
+     ;; (half the window width)
+     (let ((merge-window (get-buffer-window emerge-merge-buffer)))
+       (if (null merge-window)
+	   ;; no window, use nil
+	   nil
+	 (let ((default-amount
+		 (- (/ (window-width merge-window) 2) 3)))
+	   ;; the window was found
+	   (if arg
+	       ;; C-u as argument means half of default amount
+	       (/ default-amount 2)
+	     ;; no argument means default amount
+	     default-amount)))))))
+
+(defun emerge-scroll-reset ()
+  "Reset horizontal scrolling in Emerge.
+This resets the horizontal scrolling of all three merge buffers
+to the left margin, if they are in windows."
+  (interactive)
+  (emerge-operate-on-windows
+   (function (lambda (x) (set-window-hscroll (selected-window) 0)))
+   nil))
+
+;; Attempt to show the region nicely.
+;; If there are min-lines lines above and below the region, then don't do
+;; anything.
+;; If not, recenter the region to make it so.
+;; If that isn't possible, remove context lines balancedly from top and botton
+;; so the entire region shows.
+;; If that isn't possible, show the top of the region.
+;; BEG must be at the beginning of a line.
+(defun emerge-position-region (beg end pos)
+  ;; First test whether the entire region is visible with
+  ;; emerge-min-visible-lines above and below it
+  (if (not (and (<= (progn
+		      (move-to-window-line emerge-min-visible-lines)
+		      (point))
+		    beg)
+		(<= end (progn
+			  (move-to-window-line
+			   (- (1+ emerge-min-visible-lines)))
+			  (point)))))
+      ;; We failed that test, see if it fits at all
+      ;; Meanwhile positioning it correctly in case it doesn't fit
+      (progn
+	(set-window-start (selected-window) beg)
+	(if (pos-visible-in-window-p end)
+	    ;; Determine the number of lines that the region occupies
+	    (let ((lines 0))
+	      (while (> end (progn
+			      (move-to-window-line lines)
+			      (point)))
+		(setq lines (1+ lines)))
+	      ;; And position the beginning on the right line
+	      (goto-char beg)
+	      (recenter (/ (1+ (- (1- (window-height (selected-window)))
+				  lines))
+			   2))))))
+  (goto-char pos))
+
+(defun emerge-next-difference ()
+  "Advance to the next difference."
+  (interactive)
+  (if (< emerge-current-difference emerge-number-of-differences)
+      (let ((n (1+ emerge-current-difference)))
+	(while (and emerge-skip-prefers
+		    (< n emerge-number-of-differences)
+		    (memq (aref (aref emerge-difference-list n) 6)
+			  '(prefer-A prefer-B)))
+	  (setq n (1+ n)))
+	(let ((buffer-read-only nil))
+	  (emerge-unselect-and-select-difference n)))
+    (error "At end")))
+
+(defun emerge-previous-difference ()
+  "Go to the previous difference."
+  (interactive)
+  (if (> emerge-current-difference -1)
+      (let ((n (1- emerge-current-difference)))
+	(while (and emerge-skip-prefers
+		    (> n -1)
+		    (memq (aref (aref emerge-difference-list n) 6)
+			  '(prefer-A prefer-B)))
+	  (setq n (1- n)))
+	(let ((buffer-read-only nil))
+	  (emerge-unselect-and-select-difference n)))
+    (error "At beginning")))
+
+(defun emerge-jump-to-difference (difference-number)
+  "Go to the N-th difference."
+  (interactive "p")
+  (let ((buffer-read-only nil))
+    (setq difference-number (1- difference-number))
+    (if (and (>= difference-number -1)
+	     (< difference-number (1+ emerge-number-of-differences)))
+	(emerge-unselect-and-select-difference difference-number)
+      (error "Bad difference number"))))
+
+(defun emerge-abort ()
+  "Abort the Emerge session."
+  (interactive)
+  (emerge-quit t))
+
+(defun emerge-quit (arg)
+  "Finish the Emerge session and exit Emerge.
+Prefix argument means to abort rather than successfully finish.
+The difference depends on how the merge was started,
+but usually means to not write over one of the original files, or to signal
+to some process which invoked Emerge a failure code.
+
+Unselects the selected difference, if any, restores the read-only and modified
+flags of the merged file buffers, restores the local keymap of the merge
+buffer, and sets off various emerge flags.  Using Emerge commands in this
+buffer after this will cause serious problems."
+  (interactive "P")
+  (if (prog1
+	  (y-or-n-p
+	   (if (not arg)
+	       "Do you really want to successfully finish this merge? "
+	     "Do you really want to abort this merge? "))
+	(message ""))
+      (emerge-really-quit arg)))
+
+;; Perform the quit operations.
+(defun emerge-really-quit (arg)
+  (setq buffer-read-only nil)
+  (emerge-unselect-and-select-difference -1)
+  (emerge-restore-buffer-characteristics)
+  ;; null out the difference markers so they don't slow down future editing
+  ;; operations
+  (mapcar (function (lambda (d)
+		      (set-marker (aref d 0) nil)
+		      (set-marker (aref d 1) nil)
+		      (set-marker (aref d 2) nil)
+		      (set-marker (aref d 3) nil)
+		      (set-marker (aref d 4) nil)
+		      (set-marker (aref d 5) nil)))
+	  emerge-difference-list)
+  ;; allow them to be garbage collected
+  (setq emerge-difference-list nil)
+  ;; restore the menubar
+  ;; don't make the menubar become un-local because the major mode might
+  ;; have already made it local and added an item.
+  (delete-menu-item '("Emerge"))
+  ;; restore the local map
+  (use-local-map emerge-old-keymap)
+  ;; turn off all the emerge modes
+  (setq emerge-mode nil)
+  (setq emerge-fast-mode nil)
+  (setq emerge-edit-mode nil)
+  (setq emerge-auto-advance nil)
+  (setq emerge-skip-prefers nil)
+  ;; restore mode line
+  (kill-local-variable 'mode-line-buffer-identification)
+  (let ((emerge-prefix-argument arg))
+    (run-hooks 'emerge-quit-hook)))
+
+(defun emerge-select-A (&optional force)
+  "Select the A variant of this difference.  
+Refuses to function if this difference has been edited, i.e., if it
+is neither the A nor the B variant.
+A prefix argument forces the variant to be selected
+even if the difference has been edited."
+  (interactive "P")
+  (let ((operate
+	 (function (lambda ()
+		     (emerge-select-A-edit merge-begin merge-end A-begin A-end)
+		     (if emerge-auto-advance
+			 (emerge-next-difference)))))
+	(operate-no-change
+	 (function (lambda ()
+		     (if emerge-auto-advance
+			 (emerge-next-difference))))))
+    (emerge-select-version force operate-no-change operate operate)))
+
+;; Actually select the A variant
+(defun emerge-select-A-edit (merge-begin merge-end A-begin A-end)
+  (emerge-eval-in-buffer
+   emerge-merge-buffer
+   (delete-region merge-begin merge-end)
+   (goto-char merge-begin)
+   (insert-buffer-substring emerge-A-buffer A-begin A-end)
+   (goto-char merge-begin)
+   (aset diff-vector 6 'A)
+   (emerge-refresh-mode-line)))
+
+(defun emerge-select-B (&optional force)
+  "Select the B variant of this difference.
+Refuses to function if this difference has been edited, i.e., if it
+is neither the A nor the B variant.
+A prefix argument forces the variant to be selected
+even if the difference has been edited."
+  (interactive "P")
+  (let ((operate
+	 (function (lambda ()
+		     (emerge-select-B-edit merge-begin merge-end B-begin B-end)
+		     (if emerge-auto-advance
+			 (emerge-next-difference)))))
+	(operate-no-change
+	 (function (lambda ()
+		     (if emerge-auto-advance
+			 (emerge-next-difference))))))
+    (emerge-select-version force operate operate-no-change operate)))
+
+;; Actually select the B variant
+(defun emerge-select-B-edit (merge-begin merge-end B-begin B-end)
+  (emerge-eval-in-buffer
+   emerge-merge-buffer
+   (delete-region merge-begin merge-end)
+   (goto-char merge-begin)
+   (insert-buffer-substring emerge-B-buffer B-begin B-end)
+   (goto-char merge-begin)
+   (aset diff-vector 6 'B)
+   (emerge-refresh-mode-line)))
+
+(defun emerge-default-A (force)
+  "Make the A variant the default from here down.
+This selects the A variant for all differences from here down in the buffer
+which are still defaulted, i.e., which the user has not selected and for
+which there is no preference.
+A prefix argument forces all differences from here down that have
+selected the B version to become default-A as well."
+  (interactive "P")
+  (let ((buffer-read-only nil))
+    (let ((selected-difference emerge-current-difference)
+	  (n (max emerge-current-difference 0)))
+      (while (< n emerge-number-of-differences)
+	(let ((diff-vector (aref emerge-difference-list n)))
+	  (if (or (eq (aref diff-vector 6) 'default-B)
+		  (and force
+		       (eq (aref diff-vector 6) 'B)))
+	      (progn
+		(emerge-unselect-and-select-difference n t)
+		(emerge-select-A force)
+		(aset diff-vector 6 'default-A))))
+	(setq n (1+ n))
+	(if (zerop (% n 10))
+	    (message "Setting default to A...%d" n)))
+      (emerge-unselect-and-select-difference selected-difference)))
+  (message "Default choice is now A"))
+
+(defun emerge-default-B (force)
+  "Make the B variant the default from here down.
+This selects the B variant for all differences from here down in the buffer
+which are still defaulted, i.e., which the user has not selected and for
+which there is no preference.
+A prefix argument forces all differences from here down that have
+selected the A version to become default-B as well."
+  (interactive "P")
+  (let ((buffer-read-only nil))
+    (let ((selected-difference emerge-current-difference)
+	  (n (max emerge-current-difference 0)))
+      (while (< n emerge-number-of-differences)
+	(let ((diff-vector (aref emerge-difference-list n)))
+	  (if (or (eq (aref diff-vector 6) 'default-A)
+		  (and force
+		       (eq (aref diff-vector 6) 'A)))
+	      (progn
+		(emerge-unselect-and-select-difference n t)
+		(emerge-select-B force)
+		(aset diff-vector 6 'default-B))))
+	(setq n (1+ n))
+	(if (zerop (% n 10))
+	    (message "Setting default to B...%d" n)))
+      (emerge-unselect-and-select-difference selected-difference)))
+  (message "Default choice is now B"))
+
+(defun emerge-fast-mode ()
+  "Set fast mode, for Emerge.
+In this mode ordinary Emacs commands are disabled, and Emerge commands
+need not be prefixed with \\<emerge-fast-keymap>\\[emerge-basic-keymap]."
+  (interactive)
+  (setq buffer-read-only t)
+  (use-local-map emerge-fast-keymap)
+  (setq emerge-mode t)
+  (setq emerge-fast-mode t)
+  (setq emerge-edit-mode nil)
+  (message "Fast mode set")
+  (force-mode-line-update))
+
+(defun emerge-edit-mode ()
+  "Set edit mode, for Emerge.
+In this mode ordinary Emacs commands are available, and Emerge commands
+must be prefixed with \\<emerge-fast-keymap>\\[emerge-basic-keymap]."
+  (interactive)
+  (setq buffer-read-only nil)
+  (use-local-map emerge-edit-keymap)
+  (setq emerge-mode t)
+  (setq emerge-fast-mode nil)
+  (setq emerge-edit-mode t)
+  (message "Edit mode set")
+  (force-mode-line-update))
+
+(defun emerge-auto-advance (arg)
+  "Toggle Auto-Advance mode, for Emerge.
+This mode causes `emerge-select-A' and `emerge-select-B' to automatically
+advance to the next difference.
+With a positive argument, turn on Auto-Advance mode.
+With a negative argument, turn off Auto-Advance mode."
+  (interactive "P")
+  (setq emerge-auto-advance (if (null arg)
+				(not emerge-auto-advance)
+			      (> (prefix-numeric-value arg) 0)))
+  (message (if emerge-auto-advance
+	       "Auto-advance set"
+	     "Auto-advance cleared"))
+  (force-mode-line-update))
+
+(defun emerge-skip-prefers (arg)
+  "Toggle Skip-Prefers mode, for Emerge.
+This mode causes `emerge-next-difference' and `emerge-previous-difference'
+to automatically skip over differences for which there is a preference.
+With a positive argument, turn on Skip-Prefers mode.
+With a negative argument, turn off Skip-Prefers mode."
+  (interactive "P")
+  (setq emerge-skip-prefers (if (null arg)
+				(not emerge-skip-prefers)
+			      (> (prefix-numeric-value arg) 0)))
+  (message (if emerge-skip-prefers
+	       "Skip-prefers set"
+	     "Skip-prefers cleared"))
+  (force-mode-line-update))
+
+(defun emerge-copy-as-kill-A ()
+  "Put the A variant of this difference in the kill ring."
+  (interactive)
+  (emerge-validate-difference)
+  (let* ((diff-vector
+	  (aref emerge-difference-list emerge-current-difference))
+	 (A-begin (1+ (aref diff-vector 0)))
+	 (A-end (1- (aref diff-vector 1)))
+	 ;; so further kills don't append
+	 this-command)
+    (save-excursion
+      (set-buffer emerge-A-buffer)
+      (copy-region-as-kill A-begin A-end))))
+
+(defun emerge-copy-as-kill-B ()
+  "Put the B variant of this difference in the kill ring."
+  (interactive)
+  (emerge-validate-difference)
+  (let* ((diff-vector
+	  (aref emerge-difference-list emerge-current-difference))
+	 (B-begin (1+ (aref diff-vector 2)))
+	 (B-end (1- (aref diff-vector 3)))
+	 ;; so further kills don't append
+	 this-command)
+    (save-excursion
+      (set-buffer emerge-B-buffer)
+      (copy-region-as-kill B-begin B-end))))
+
+(defun emerge-insert-A (arg)
+  "Insert the A variant of this difference at the point.
+Leaves point after text, mark before.
+With prefix argument, puts point before, mark after."
+  (interactive "P")
+  (emerge-validate-difference)
+  (let* ((diff-vector
+	  (aref emerge-difference-list emerge-current-difference))
+	 (A-begin (1+ (aref diff-vector 0)))
+	 (A-end (1- (aref diff-vector 1)))
+	 (opoint (point))
+	 (buffer-read-only nil))
+    (insert-buffer-substring emerge-A-buffer A-begin A-end)
+    (if (not arg)
+	(set-mark opoint)
+      (set-mark (point))
+      (goto-char opoint))))
+
+(defun emerge-insert-B (arg)
+  "Insert the B variant of this difference at the point.
+Leaves point after text, mark before.
+With prefix argument, puts point before, mark after."
+  (interactive "P")
+  (emerge-validate-difference)
+  (let* ((diff-vector
+	  (aref emerge-difference-list emerge-current-difference))
+	 (B-begin (1+ (aref diff-vector 2)))
+	 (B-end (1- (aref diff-vector 3)))
+	 (opoint (point))
+	 (buffer-read-only nil))
+    (insert-buffer-substring emerge-B-buffer B-begin B-end)
+    (if (not arg)
+	(set-mark opoint)
+      (set-mark (point))
+      (goto-char opoint))))
+
+(defun emerge-mark-difference (arg)
+  "Leaves the point before this difference and the mark after it.
+With prefix argument, puts mark before, point after."
+  (interactive "P")
+  (emerge-validate-difference)
+  (let* ((diff-vector
+	  (aref emerge-difference-list emerge-current-difference))
+	 (merge-begin (1+ (aref diff-vector 4)))
+	 (merge-end (1- (aref diff-vector 5))))
+    (if (not arg)
+	(progn
+	  (goto-char merge-begin)
+	  (set-mark merge-end))
+      (goto-char merge-end)
+      (set-mark merge-begin))))
+
+(defun emerge-file-names ()
+  "Show the names of the buffers or files being operated on by Emerge.
+Use C-u l to reset the windows afterward."
+  (interactive)
+  (delete-other-windows)
+  (let ((temp-buffer-show-function
+	 (function
+	  (lambda (buf)
+	    ;; in v18, split-window and split-window-vertically were the same,
+	    ;; but in v19, split-window-vertically might select the other
+	    ;; window.
+	    ;; (split-window-vertically)
+	    (switch-to-buffer buf)
+	    (other-window 1)))))
+    (with-output-to-temp-buffer "*Help*"
+      (emerge-eval-in-buffer emerge-A-buffer
+			     (if buffer-file-name
+				 (progn
+				   (princ "File A is: ")
+				   (princ buffer-file-name))
+			       (progn
+				 (princ "Buffer A is: ")
+				 (princ (buffer-name))))
+			     (princ "\n"))
+      (emerge-eval-in-buffer emerge-B-buffer
+			     (if buffer-file-name
+				 (progn
+				   (princ "File B is: ")
+				   (princ buffer-file-name))
+			       (progn
+				 (princ "Buffer B is: ")
+				 (princ (buffer-name))))
+			     (princ "\n"))
+      (if emerge-ancestor-buffer
+	    (emerge-eval-in-buffer emerge-ancestor-buffer
+				   (if buffer-file-name
+				       (progn
+					 (princ "Ancestor file is: ")
+					 (princ buffer-file-name))
+				     (progn
+				       (princ "Ancestor buffer is: ")
+				       (princ (buffer-name))))
+				   (princ "\n")))
+      (princ emerge-output-description)
+      (save-excursion
+	(set-buffer standard-output)
+	(help-mode)))))
+
+(defun emerge-join-differences (arg)
+  "Join the selected difference with the following one.
+With a prefix argument, join with the preceding one."
+  (interactive "P")
+  (let ((n emerge-current-difference))
+    ;; adjust n to be first difference to join
+    (if arg
+	(setq n (1- n)))
+    ;; n and n+1 are the differences to join
+    ;; check that they are both differences
+    (if (or (< n 0) (>= n (1- emerge-number-of-differences)))
+	(error "Incorrect differences to join"))
+    ;; remove the flags
+    (emerge-unselect-difference emerge-current-difference)
+    ;; decrement total number of differences
+    (setq emerge-number-of-differences (1- emerge-number-of-differences))
+    ;; build new differences vector
+    (let ((i 0)
+	  (new-differences (make-vector emerge-number-of-differences nil)))
+      (while (< i emerge-number-of-differences)
+	(aset new-differences i
+	      (cond
+	       ((< i n) (aref emerge-difference-list i))
+	       ((> i n) (aref emerge-difference-list (1+ i)))
+	       (t (let ((prev (aref emerge-difference-list i))
+			(next (aref emerge-difference-list (1+ i))))
+		    (vector (aref prev 0)
+			    (aref next 1)
+			    (aref prev 2)
+			    (aref next 3)
+			    (aref prev 4)
+			    (aref next 5)
+			    (let ((ps (aref prev 6))
+				  (ns (aref next 6)))
+			      (cond
+			       ((eq ps ns)
+				ps)
+			       ((and (or (eq ps 'B) (eq ps 'prefer-B))
+				     (or (eq ns 'B) (eq ns 'prefer-B)))
+				'B)
+			       (t 'A))))))))
+	(setq i (1+ i)))
+      (setq emerge-difference-list new-differences))
+    ;; set the current difference correctly
+    (setq emerge-current-difference n)
+    ;; fix the mode line
+    (emerge-refresh-mode-line)
+    ;; reinsert the flags
+    (emerge-select-difference emerge-current-difference)
+    (emerge-recenter)))
+
+(defun emerge-split-difference ()
+  "Split the current difference where the points are in the three windows."
+  (interactive)
+  (let ((n emerge-current-difference))
+    ;; check that this is a valid difference
+    (emerge-validate-difference)
+    ;; get the point values and old difference
+    (let ((A-point (emerge-eval-in-buffer emerge-A-buffer
+					  (point-marker)))
+	  (B-point (emerge-eval-in-buffer emerge-B-buffer
+					  (point-marker)))
+	  (merge-point (point-marker))
+	  (old-diff (aref emerge-difference-list n)))
+      ;; check location of the points, give error if they aren't in the
+      ;; differences
+      (if (or (< A-point (aref old-diff 0))
+	      (> A-point (aref old-diff 1)))
+	  (error "Point outside of difference in A buffer"))
+      (if (or (< B-point (aref old-diff 2))
+	      (> B-point (aref old-diff 3)))
+	  (error "Point outside of difference in B buffer"))
+      (if (or (< merge-point (aref old-diff 4))
+	      (> merge-point (aref old-diff 5)))
+	  (error "Point outside of difference in merge buffer"))
+      ;; remove the flags
+      (emerge-unselect-difference emerge-current-difference)
+      ;; increment total number of differences
+      (setq emerge-number-of-differences (1+ emerge-number-of-differences))
+      ;; build new differences vector
+      (let ((i 0)
+	    (new-differences (make-vector emerge-number-of-differences nil)))
+	(while (< i emerge-number-of-differences)
+	  (aset new-differences i
+		(cond
+		 ((< i n)
+		  (aref emerge-difference-list i))
+		 ((> i (1+ n))
+		  (aref emerge-difference-list (1- i)))
+		 ((= i n)
+		  (vector (aref old-diff 0)
+			  A-point
+			  (aref old-diff 2)
+			  B-point
+			  (aref old-diff 4)
+			  merge-point
+			  (aref old-diff 6)))
+		 (t
+		  (vector (copy-marker A-point)
+			  (aref old-diff 1)
+			  (copy-marker B-point)
+			  (aref old-diff 3)
+			  (copy-marker merge-point)
+			  (aref old-diff 5)
+			  (aref old-diff 6)))))
+	  (setq i (1+ i)))
+	(setq emerge-difference-list new-differences))
+      ;; set the current difference correctly
+      (setq emerge-current-difference n)
+      ;; fix the mode line
+      (emerge-refresh-mode-line)
+      ;; reinsert the flags
+      (emerge-select-difference emerge-current-difference)
+      (emerge-recenter))))
+
+(defun emerge-trim-difference ()
+  "Trim lines off top and bottom of difference that are the same.
+If lines are the same in both the A and the B versions, strip them off.
+\(This can happen when the A and B versions have common lines that the
+ancestor version does not share.)"
+  (interactive)
+  ;; make sure we are in a real difference
+  (emerge-validate-difference)
+  ;; remove the flags
+  (emerge-unselect-difference emerge-current-difference)
+  (let* ((diff (aref emerge-difference-list emerge-current-difference))
+	 (top-a (marker-position (aref diff 0)))
+	 (bottom-a (marker-position (aref diff 1)))
+	 (top-b (marker-position (aref diff 2)))
+	 (bottom-b (marker-position (aref diff 3)))
+	 (top-m (marker-position (aref diff 4)))
+	 (bottom-m (marker-position (aref diff 5)))
+	 size success sa sb sm)
+    ;; move down the tops of the difference regions as much as possible
+    ;; Try advancing comparing 1000 chars at a time.
+    ;; When that fails, go 500 chars at a time, and so on.
+    (setq size 1000)
+    (while (> size 0)
+      (setq success t)
+      (while success
+	(setq size (min size (- bottom-a top-a) (- bottom-b top-b)
+			(- bottom-m top-m)))
+	(setq sa (emerge-eval-in-buffer emerge-A-buffer
+					(buffer-substring top-a
+							  (+ size top-a))))
+	(setq sb (emerge-eval-in-buffer emerge-B-buffer
+					(buffer-substring top-b
+							  (+ size top-b))))
+	(setq sm (buffer-substring top-m (+ size top-m)))
+	(setq success (and (> size 0) (equal sa sb) (equal sb sm)))
+	(if success
+	    (setq top-a (+ top-a size)
+		  top-b (+ top-b size)
+		  top-m (+ top-m size))))
+      (setq size (/ size 2)))
+    ;; move up the bottoms of the difference regions as much as possible
+    ;; Try advancing comparing 1000 chars at a time.
+    ;; When that fails, go 500 chars at a time, and so on.
+    (setq size 1000)
+    (while (> size 0)
+      (setq success t)
+      (while success
+	(setq size (min size (- bottom-a top-a) (- bottom-b top-b)
+			(- bottom-m top-m)))
+	(setq sa (emerge-eval-in-buffer emerge-A-buffer
+					(buffer-substring (- bottom-a size)
+							  bottom-a)))
+	(setq sb (emerge-eval-in-buffer emerge-B-buffer
+					(buffer-substring (- bottom-b size)
+							  bottom-b)))
+	(setq sm (buffer-substring (- bottom-m size) bottom-m))
+	(setq success (and (> size 0) (equal sa sb) (equal sb sm)))
+	(if success
+	    (setq bottom-a (- bottom-a size)
+		  bottom-b (- bottom-b size)
+		  bottom-m (- bottom-m size))))
+      (setq size (/ size 2)))
+    ;; {top,bottom}-{a,b,m} are now set at the new beginnings and ends
+    ;; of the difference regions.  Move them to the beginning of lines, as
+    ;; appropriate.
+    (emerge-eval-in-buffer emerge-A-buffer
+			   (goto-char top-a)
+			   (beginning-of-line)
+			   (aset diff 0 (point-marker))
+			   (goto-char bottom-a)
+			   (beginning-of-line 2)
+			   (aset diff 1 (point-marker)))
+    (emerge-eval-in-buffer emerge-B-buffer
+			   (goto-char top-b)
+			   (beginning-of-line)
+			   (aset diff 2 (point-marker))
+			   (goto-char bottom-b)
+			   (beginning-of-line 2)
+			   (aset diff 3 (point-marker)))
+    (goto-char top-m)
+    (beginning-of-line)
+    (aset diff 4 (point-marker))
+    (goto-char bottom-m)
+    (beginning-of-line 2)
+    (aset diff 5 (point-marker))
+    ;; put the flags back in, recenter the display
+    (emerge-select-difference emerge-current-difference)
+    (emerge-recenter)))
+
+(defun emerge-find-difference (arg)
+  "Find the difference containing the current position of the point.
+If there is no containing difference and the prefix argument is positive,
+it finds the nearest following difference.  A negative prefix argument finds
+the nearest previous difference."
+  (interactive "P")
+  ;; search for the point in the merge buffer, using the markers
+  ;; for the beginning and end of the differences in the merge buffer
+  (cond ((eq (current-buffer) emerge-A-buffer)
+	 (emerge-find-difference-A arg))
+	((eq (current-buffer) emerge-B-buffer)
+	 (emerge-find-difference-B arg))
+	(t (emerge-find-difference-merge arg))))
+
+(defun emerge-find-difference-merge (arg)
+  "Find the difference containing point, in the merge buffer.
+If there is no containing difference and the prefix argument is positive,
+it finds the nearest following difference.  A negative prefix argument finds
+the nearest previous difference."
+  (interactive "P")
+  ;; search for the point in the merge buffer, using the markers
+  ;; for the beginning and end of the differences in the merge buffer
+  (emerge-find-difference1 arg (point) 4 5))
+
+(defun emerge-find-difference-A (arg)
+  "Find the difference containing point, in the A buffer.
+This command must be executed in the merge buffer.
+If there is no containing difference and the prefix argument is positive,
+it finds the nearest following difference.  A negative prefix argument finds
+the nearest previous difference."
+  (interactive "P")
+  ;; search for the point in the A buffer, using the markers
+  ;; for the beginning and end of the differences in the A buffer
+  (emerge-find-difference1 arg
+			   (emerge-eval-in-buffer emerge-A-buffer (point))
+			   0 1))
+
+(defun emerge-find-difference-B (arg)
+  "Find the difference containing point, in the B buffer.
+This command must be executed in the merge buffer.
+If there is no containing difference and the prefix argument is positive,
+it finds the nearest following difference.  A negative prefix argument finds
+the nearest previous difference."
+  (interactive "P")
+  ;; search for the point in the B buffer, using the markers
+  ;; for the beginning and end of the differences in the B buffer
+  (emerge-find-difference1 arg
+			   (emerge-eval-in-buffer emerge-B-buffer (point))
+			   2 3))
+
+(defun emerge-find-difference1 (arg location begin end)
+  (let* ((index
+	  ;; find first difference containing or after the current position
+	  (catch 'search
+	    (let ((n 0))
+	      (while (< n emerge-number-of-differences)
+		(let ((diff-vector (aref emerge-difference-list n)))
+		  (if (<= location (marker-position (aref diff-vector end)))
+		      (throw 'search n)))
+		(setq n (1+ n))))
+	    emerge-number-of-differences))
+	 (contains
+	  ;; whether the found difference contains the current position
+	  (and (< index emerge-number-of-differences)
+	       (<= (marker-position (aref (aref emerge-difference-list index)
+					  begin))
+		   location)))
+	 (arg-value
+	  ;; numeric value of prefix argument
+	  (prefix-numeric-value arg)))
+    (emerge-unselect-and-select-difference
+     (cond
+      ;; if the point is in a difference, select it
+      (contains index)
+      ;; if the arg is nil and the point is not in a difference, error
+      ((null arg) (error "No difference contains point"))
+      ;; if the arg is positive, select the following difference
+      ((> arg-value 0)
+       (if (< index emerge-number-of-differences)
+	   index
+	 (error "No difference contains or follows point")))
+      ;; if the arg is negative, select the preceding difference
+      (t
+       (if (> index 0)
+	   (1- index)
+	 (error "No difference contains or precedes point")))))))
+
+(defun emerge-line-numbers ()
+  "Display the current line numbers.
+This function displays the line numbers of the points in the A, B, and
+merge buffers."
+  (interactive)
+  (let* ((valid-diff
+	 (and (>= emerge-current-difference 0)
+	      (< emerge-current-difference emerge-number-of-differences)))
+	(diff (and valid-diff
+		   (aref emerge-difference-list emerge-current-difference)))
+	(merge-line (emerge-line-number-in-buf 4 5))
+	(A-line (emerge-eval-in-buffer emerge-A-buffer
+				       (emerge-line-number-in-buf 0 1)))
+	(B-line (emerge-eval-in-buffer emerge-B-buffer
+				       (emerge-line-number-in-buf 2 3))))
+    (message "At lines: merge = %d, A = %d, B = %d"
+	     merge-line A-line B-line)))
+
+(defun emerge-line-number-in-buf (begin-marker end-marker)
+  (let (temp)
+    (setq temp (save-excursion
+		 (beginning-of-line)
+		 (1+ (count-lines 1 (point)))))
+    (if valid-diff
+	(progn
+	  (if (> (point) (aref diff begin-marker))
+	      (setq temp (- temp emerge-before-flag-lines)))
+	  (if (> (point) (aref diff end-marker))
+	      (setq temp (- temp emerge-after-flag-lines)))))
+    temp))
+
+(defun emerge-set-combine-template (string &optional localize)
+  "Set `emerge-combine-versions-template' to STRING.
+This value controls how `emerge-combine-versions' combines the two versions.
+With prefix argument, `emerge-combine-versions-template' is made local to this
+merge buffer.  Localization is permanent for any particular merge buffer."
+  (interactive "s\nP")
+  (if localize
+      (make-local-variable 'emerge-combine-versions-template))
+  (setq emerge-combine-versions-template string)
+  (message
+   (if (assq 'emerge-combine-versions-template (buffer-local-variables))
+       "emerge-set-combine-versions-template set locally"
+     "emerge-set-combine-versions-template set")))
+
+(defun emerge-set-combine-versions-template (start end &optional localize)
+  "Copy region into `emerge-combine-versions-template'.
+This controls how `emerge-combine-versions' will combine the two versions.
+With prefix argument, `emerge-combine-versions-template' is made local to this
+merge buffer.  Localization is permanent for any particular merge buffer."
+  (interactive "r\nP")
+  (if localize
+      (make-local-variable 'emerge-combine-versions-template))
+  (setq emerge-combine-versions-template (buffer-substring start end))
+  (message
+   (if (assq 'emerge-combine-versions-template (buffer-local-variables))
+       "emerge-set-combine-versions-template set locally."
+     "emerge-set-combine-versions-template set.")))
+
+(defun emerge-combine-versions (&optional force)
+  "Combine versions using the template in `emerge-combine-versions-template'.
+Refuses to function if this difference has been edited, i.e., if it is
+neither the A nor the B variant.
+An argument forces the variant to be selected even if the difference has
+been edited."
+  (interactive "P")
+  (emerge-combine-versions-internal emerge-combine-versions-template force))
+
+(defun emerge-combine-versions-register (char &optional force)
+  "Combine the two versions using the template in register REG.
+See documentation of the variable `emerge-combine-versions-template'
+for how the template is interpreted.
+Refuses to function if this difference has been edited, i.e., if it is
+neither the A nor the B variant.
+An argument forces the variant to be selected even if the difference has
+been edited."
+  (interactive "cRegister containing template: \nP")
+  (let ((template (get-register char)))
+    (if (not (stringp template))
+	(error "Register does not contain text"))
+    (emerge-combine-versions-internal template force)))
+
+(defun emerge-combine-versions-internal (template force)
+  (let ((operate
+	 (function (lambda ()
+		     (emerge-combine-versions-edit merge-begin merge-end
+						   A-begin A-end B-begin B-end
+						   template)
+		     (if emerge-auto-advance
+			 (emerge-next-difference))))))
+    (emerge-select-version force operate operate operate)))
+
+(defun emerge-combine-versions-edit (merge-begin merge-end
+				     A-begin A-end B-begin B-end
+				     template)
+  (emerge-eval-in-buffer
+   emerge-merge-buffer
+   (delete-region merge-begin merge-end)
+   (goto-char merge-begin)
+   (let ((i 0))
+     (while (< i (length template))
+       (let ((c (aref template i)))
+	 (if (= c ?%)
+	     (progn
+	       (setq i (1+ i))
+	       (setq c 
+		     (condition-case nil
+			 (aref template i)
+		       (error ?%)))
+	       (cond ((= c ?a)
+		      (insert-buffer-substring emerge-A-buffer A-begin A-end))
+		     ((= c ?b) 
+		      (insert-buffer-substring emerge-B-buffer B-begin B-end))
+		     ((= c ?%) 
+		      (insert ?%))
+		     (t
+		      (insert c))))
+	   (insert c)))
+       (setq i (1+ i))))
+   (goto-char merge-begin)
+   (aset diff-vector 6 'combined)
+   (emerge-refresh-mode-line)))
+
+(defun emerge-set-merge-mode (mode)
+  "Set the major mode in a merge buffer.
+Overrides any change that the mode might make to the mode line or local
+keymap.  Leaves merge in fast mode."
+  (interactive
+   (list (intern (completing-read "New major mode for merge buffer: "
+				  obarray 'commandp t nil))))
+  (funcall mode)
+  (emerge-refresh-mode-line)
+  (if emerge-fast-mode
+      (emerge-fast-mode)
+    (emerge-edit-mode)))
+
+(defun emerge-one-line-window ()
+  (interactive)
+  (let ((window-min-height 1))
+    (shrink-window (- (window-height) 2))))
+
+;;; Support routines
+
+;; Select a difference by placing the visual flags around the appropriate
+;; group of lines in the A, B, and merge buffers
+(defun emerge-select-difference (n)
+  (let ((emerge-globalized-difference-list emerge-difference-list)
+	(emerge-globalized-number-of-differences emerge-number-of-differences))
+    (emerge-place-flags-in-buffer emerge-A-buffer n 0 1)
+    (emerge-place-flags-in-buffer emerge-B-buffer n 2 3)
+    (emerge-place-flags-in-buffer nil n 4 5))
+  (run-hooks 'emerge-select-hook))
+
+(defun emerge-place-flags-in-buffer (buffer difference before-index
+					    after-index)
+  (if buffer
+      (emerge-eval-in-buffer
+       buffer
+       (emerge-place-flags-in-buffer1 difference before-index after-index))
+    (emerge-place-flags-in-buffer1 difference before-index after-index)))
+
+(defun emerge-place-flags-in-buffer1 (difference before-index after-index)
+  (if (and emerge-xemacs-p (not emerge-mark-with-text))
+      ;; XEmacs highlights the difference
+      (emerge-place-flags-in-buffer1-xemacs difference before-index after-index)
+    ;; Else insert character flags
+    (let ((buffer-read-only nil))
+      ;; insert the flag before the difference
+      (let ((before (aref (aref emerge-globalized-difference-list difference)
+			  before-index))
+	    here)
+	(goto-char before)
+	;; insert the flag itself
+	(insert-before-markers emerge-before-flag)
+	(setq here (point))
+	;; Put the marker(s) referring to this position 1 character before the
+	;; end of the flag, so it won't be damaged by the user.
+	;; This gets a bit tricky, as there could be a number of markers
+	;; that have to be moved.
+	(set-marker before (1- before))
+	(let ((n (1- difference)) after-marker before-marker diff-list)
+	  (while (and
+		  (>= n 0)
+		  (progn
+		    (setq diff-list (aref emerge-globalized-difference-list n)
+			  after-marker (aref diff-list after-index))
+		    (= after-marker here)))
+	    (set-marker after-marker (1- after-marker))
+	    (setq before-marker (aref diff-list before-index))
+	    (if (= before-marker here)
+		(setq before-marker (1- before-marker)))
+	    (setq n (1- n)))))
+      ;; insert the flag after the difference
+      (let* ((after (aref (aref emerge-globalized-difference-list difference)
+			  after-index))
+	     (here (marker-position after)))
+	(goto-char here)
+	;; insert the flag itself
+	(insert emerge-after-flag)
+	;; Put the marker(s) referring to this position 1 character after the
+	;; beginning of the flag, so it won't be damaged by the user.
+	;; This gets a bit tricky, as there could be a number of markers
+	;; that have to be moved.
+	(set-marker after (1+ after))
+	(let ((n (1+ difference)) before-marker after-marker diff-list)
+	  (while (and
+		  (< n emerge-globalized-number-of-differences)
+		  (progn
+		    (setq diff-list (aref emerge-globalized-difference-list n)
+			  before-marker (aref diff-list before-index))
+		    (= before-marker here)))
+	    (set-marker before-marker (1+ before-marker))
+	    (setq after-marker (aref diff-list after-index))
+	    (if (= after-marker here)
+		(setq after-marker (1+ after-marker)))
+	    (setq n (1+ n))))))))
+
+(defun emerge-place-flags-in-buffer1-xemacs (difference before-index
+						       after-index)
+  (let* ((before (aref (aref emerge-globalized-difference-list difference)
+		       before-index))
+	 (after (aref (aref emerge-globalized-difference-list difference)
+		      after-index))
+	 (extent (make-extent (marker-position before) (marker-position after)
+			      (current-buffer))))
+    (set-extent-face extent 'emerge-highlight-face)
+    ;; Assert that this extent is slightly more important than random other
+    ;; extents that may have been inserted by things like font-lock-mode.
+    ;; This way, any conflict between the display of a highlighting face
+    ;; and the emerge face will be resolved in emerge's favor.
+    (set-extent-priority extent 1)
+    (set-extent-property extent 'emerge t)))
+
+;; Unselect a difference by removing the visual flags in the buffers.
+(defun emerge-unselect-difference (n)
+  (let ((diff-vector (aref emerge-difference-list n)))
+    (emerge-remove-flags-in-buffer emerge-A-buffer
+				   (aref diff-vector 0) (aref diff-vector 1))
+    (emerge-remove-flags-in-buffer emerge-B-buffer
+				   (aref diff-vector 2) (aref diff-vector 3))
+    (emerge-remove-flags-in-buffer emerge-merge-buffer
+				   (aref diff-vector 4) (aref diff-vector 5)))
+  (run-hooks 'emerge-unselect-hook))
+
+(defun emerge-remove-flags-in-buffer (buffer before after)
+  (if (and emerge-xemacs-p (not emerge-mark-with-text))
+      ;; XEmacs -- remove highlighting
+      (emerge-remove-flags-in-buffer-xemacs buffer before after)
+    ;; Else remove character flags
+    (emerge-eval-in-buffer
+     buffer
+     (let ((buffer-read-only nil))
+       ;; remove the flags, if they're there
+       (goto-char (- before (1- emerge-before-flag-length)))
+       (if (looking-at emerge-before-flag-match)
+	   (delete-char emerge-before-flag-length)
+	 ;; the flag isn't there
+	 (ding)
+	 (message "Trouble removing flag"))
+       (goto-char (1- after))
+       (if (looking-at emerge-after-flag-match)
+	   (delete-char emerge-after-flag-length)
+	 ;; the flag isn't there
+	 (ding)
+	 (message "Trouble removing flag"))))))
+
+(defun emerge-remove-flags-in-buffer-xemacs (buffer before after)
+  (map-extents (function (lambda (x y)
+			   (if (extent-property x 'emerge)
+			       (delete-extent x))))
+               buffer (marker-position before) (marker-position after) nil))
+
+;; Select a difference, removing any flags that exist now.
+(defun emerge-unselect-and-select-difference (n &optional suppress-display)
+  (if (and (>= emerge-current-difference 0)
+	   (< emerge-current-difference emerge-number-of-differences))
+      (emerge-unselect-difference emerge-current-difference))
+  (if (and (>= n 0) (< n emerge-number-of-differences))
+      (progn
+	(emerge-select-difference n)
+	(let* ((diff-vector (aref emerge-difference-list n))
+	       (selection-type (aref diff-vector 6)))
+	  (if (eq selection-type 'default-A)
+	      (aset diff-vector 6 'A)
+	    (if (eq selection-type 'default-B)
+		(aset diff-vector 6 'B))))))
+  (setq emerge-current-difference n)
+  (if (not suppress-display)
+      (progn
+	(emerge-recenter)
+	(emerge-refresh-mode-line))))
+
+;; Perform tests to see whether user should be allowed to select a version
+;; of this difference:
+;;   a valid difference has been selected; and
+;;   the difference text in the merge buffer is:
+;;     the A version (execute a-version), or
+;;     the B version (execute b-version), or
+;;     empty (execute neither-version), or
+;;     argument FORCE is true (execute neither-version)
+;; Otherwise, signal an error.
+(defun emerge-select-version (force a-version b-version neither-version)
+  (emerge-validate-difference)
+  (let ((buffer-read-only nil))
+    (let* ((diff-vector
+	    (aref emerge-difference-list emerge-current-difference))
+	   (A-begin (1+ (aref diff-vector 0)))
+	   (A-end (1- (aref diff-vector 1)))
+	   (B-begin (1+ (aref diff-vector 2)))
+	   (B-end (1- (aref diff-vector 3)))
+	   (merge-begin (1+ (aref diff-vector 4)))
+	   (merge-end (1- (aref diff-vector 5))))
+      (if (emerge-compare-buffers emerge-A-buffer A-begin A-end
+				  emerge-merge-buffer merge-begin
+				  merge-end)
+	  (funcall a-version)
+	(if (emerge-compare-buffers emerge-B-buffer B-begin B-end
+				    emerge-merge-buffer merge-begin
+				    merge-end)
+	    (funcall b-version)
+	  (if (or force (= merge-begin merge-end))
+	      (funcall neither-version)
+	    (error "This difference region has been edited")))))))
+
+;; Read a file name, handling all of the various defaulting rules.
+
+(defun emerge-read-file-name (prompt alternative-default-dir default-file
+			      A-file must-match)
+  ;; `prompt' should not have trailing ": ", so that it can be modified
+  ;; according to context.
+  ;; If alternative-default-dir is non-nil, it should be used as the default
+  ;; directory instead if default-directory, if emerge-default-last-directories
+  ;; is set.
+  ;; If default-file is set, it should be used as the default value.
+  ;; If A-file is set, and its directory is different from
+  ;; alternative-default-dir, and if emerge-default-last-directories is set,
+  ;; the default file should be the last part of A-file in the default
+  ;; directory.  (Overriding default-file.)
+  ;; 'must-match' controlls whether non-existent file names are allowed;
+  ;; see the fourth argument of read-file-name for interpretations of values.
+  (cond
+   ;; If this is not the A-file argument (shown by non-nil A-file), and
+   ;; if emerge-default-last-directories is set, and
+   ;; the default directory exists but is not the same as the directory of the
+   ;; A-file,
+   ;; then make the default file have the same name as the A-file, but in
+   ;; the default directory.
+   ((and emerge-default-last-directories
+	 A-file
+	 alternative-default-dir
+	 (not (string-equal alternative-default-dir
+			    (file-name-directory A-file))))
+    (read-file-name (format "%s (default %s): "
+			    prompt (file-name-nondirectory A-file))
+		    alternative-default-dir
+		    (concat alternative-default-dir
+			    (file-name-nondirectory A-file))
+		    (and must-match 'confirm)))
+   ;; If there is a default file, use it.
+   (default-file
+     (read-file-name (format "%s (default %s): " prompt default-file)
+		     ;; If emerge-default-last-directories is set, use the
+		     ;; directory from the same argument of the last call of
+		     ;; Emerge as the default for this argument.
+		     (and emerge-default-last-directories
+			  alternative-default-dir)
+		     default-file (and must-match 'confirm)))
+   (t
+    (read-file-name (concat prompt ": ")
+		    ;; If emerge-default-last-directories is set, use the
+		    ;; directory from the same argument of the last call of
+		    ;; Emerge as the default for this argument.
+		    (and emerge-default-last-directories
+			 alternative-default-dir)
+		    nil (and must-match 'confirm)))))
+
+;; Revise the mode line to display which difference we have selected
+
+(defun emerge-refresh-mode-line ()
+  (setq mode-line-buffer-identification
+	(list (format "Emerge: %%b   diff %d of %d%s"
+		      (1+ emerge-current-difference)
+		      emerge-number-of-differences
+		      (if (and (>= emerge-current-difference 0)
+			       (< emerge-current-difference
+				  emerge-number-of-differences))
+			  (cdr (assq (aref (aref emerge-difference-list
+						 emerge-current-difference)
+					   6)
+				     '((A . " - A")
+				       (B . " - B")
+				       (prefer-A . " - A*")
+				       (prefer-B . " - B*")
+				       (combined . " - comb"))))
+			""))))
+  (force-mode-line-update))
+
+;; compare two regions in two buffers for containing the same text
+(defun emerge-compare-buffers (buffer-x x-begin x-end buffer-y y-begin y-end)
+  ;; first check that the two regions are the same length
+  (if (not (and (= (- x-end x-begin) (- y-end y-begin))))
+      nil
+    (catch 'exit
+      (while (< x-begin x-end)
+	;; bite off and compare no more than 1000 characters at a time
+	(let* ((compare-length (min (- x-end x-begin) 1000))
+	       (x-string (emerge-eval-in-buffer 
+			  buffer-x
+			  (buffer-substring x-begin
+					    (+ x-begin compare-length))))
+	       (y-string (emerge-eval-in-buffer
+			  buffer-y
+			  (buffer-substring y-begin
+					    (+ y-begin compare-length)))))
+	  (if (not (string-equal x-string y-string))
+	      (throw 'exit nil)
+	    (setq x-begin (+ x-begin compare-length))
+	    (setq y-begin (+ y-begin compare-length)))))
+      t)))
+
+;; Construct a unique buffer name.
+;; The first one tried is prefixsuffix, then prefix<2>suffix, 
+;; prefix<3>suffix, etc.
+(defun emerge-unique-buffer-name (prefix suffix)
+  (if (null (get-buffer (concat prefix suffix)))
+      (concat prefix suffix)
+    (let ((n 2))
+      (while (get-buffer (format "%s<%d>%s" prefix n suffix))
+	(setq n (1+ n)))
+      (format "%s<%d>%s" prefix n suffix))))
+
+;; Verify that we have a difference selected.
+(defun emerge-validate-difference ()
+  (if (not (and (>= emerge-current-difference 0)
+		(< emerge-current-difference emerge-number-of-differences)))
+      (error "No difference selected")))
+
+;;; Functions for saving and restoring a batch of variables
+
+;; These functions save (get the values of) and restore (set the values of)
+;; a list of variables.  The argument is a list of symbols (the names of
+;; the variables).  A list element can also be a list of two functions,
+;; the first of which (when called with no arguments) gets the value, and
+;; the second (when called with a value as an argment) sets the value.
+;; A "function" is anything that funcall can handle as an argument.
+
+(defun emerge-save-variables (vars)
+  (mapcar (function (lambda (v) (if (symbolp v)
+				    (symbol-value v)
+				  (funcall (car v)))))
+	  vars))
+
+(defun emerge-restore-variables (vars values)
+  (while vars
+    (let ((var (car vars))
+	  (value (car values)))
+      (if (symbolp var)
+	  (set var value)
+	(funcall (car (cdr var)) value)))
+    (setq vars (cdr vars))
+    (setq values (cdr values))))
+
+;; Make a temporary file that only we have access to.
+;; PREFIX is appended to emerge-temp-file-prefix to make the filename prefix.
+(defun emerge-make-temp-file (prefix)
+  (let ((f (make-temp-name (concat emerge-temp-file-prefix prefix))))
+    ;; create the file
+    (write-region (point-min) (point-min) f nil 'no-message)
+    (set-file-modes f emerge-temp-file-mode)
+    f))
+
+;;; Functions that query the user before he can write out the current buffer.
+
+(defun emerge-query-write-file ()
+  "Ask the user whether to write out an incomplete merge.
+If answer is yes, call `write-file' to do so.  See `emerge-query-and-call'
+for details of the querying process."
+  (interactive)
+  (emerge-query-and-call 'write-file))
+
+(defun emerge-query-save-buffer ()
+  "Ask the user whether to save an incomplete merge.
+If answer is yes, call `save-buffer' to do so.  See `emerge-query-and-call'
+for details of the querying process."
+  (interactive)
+  (emerge-query-and-call 'save-buffer))
+
+(defun emerge-query-and-call (command)
+  "Ask the user whether to save or write out the incomplete merge.
+If answer is yes, call COMMAND interactively.  During the call, the flags
+around the current difference are removed."
+  (if (yes-or-no-p "Do you really write to write out this unfinished merge? ")
+      ;; He really wants to do it -- unselect the difference for the duration
+      (progn
+	(if (and (>= emerge-current-difference 0)
+		 (< emerge-current-difference emerge-number-of-differences))
+	    (emerge-unselect-difference emerge-current-difference))
+	;; call-interactively takes the value of current-prefix-arg as the
+	;; prefix argument value to be passed to the command.  Thus, we have
+	;; to do nothing special to make sure the prefix argument is
+	;; transmitted to the command.
+	(call-interactively command)
+	(if (and (>= emerge-current-difference 0)
+		 (< emerge-current-difference emerge-number-of-differences))
+	    (progn
+	      (emerge-select-difference emerge-current-difference)
+	      (emerge-recenter))))
+    ;; He's being smart and not doing it
+    (message "Not written")))
+
+;; Make sure the current buffer (for a file) has the same contents as the
+;; file on disk, and attempt to remedy the situation if not.
+;; Signal an error if we can't make them the same, or the user doesn't want
+;; to do what is necessary to make them the same.
+(defun emerge-verify-file-buffer ()
+  ;; First check if the file has been modified since the buffer visited it.
+  (if (verify-visited-file-modtime (current-buffer))
+      (if (buffer-modified-p)
+	  ;; If buffer is not obsolete and is modified, offer to save
+	  (if (yes-or-no-p (format "Save file %s? " buffer-file-name))
+	      (save-buffer)
+	    (error "Buffer out of sync for file %s" buffer-file-name))
+	;; If buffer is not obsolete and is not modified, do nothing
+	nil)
+    (if (buffer-modified-p)
+	;; If buffer is obsolete and is modified, give error
+	(error "Buffer out of sync for file %s" buffer-file-name)
+      ;; If buffer is obsolete and is not modified, offer to revert
+      (if (yes-or-no-p (format "Revert file %s? " buffer-file-name))
+	      (revert-buffer t t)
+	(error "Buffer out of sync for file %s" buffer-file-name)))))
+
+;; Returns true if the file visited in the current buffer is not accessible
+;; through its filename, or for some other reason should be stored in a
+;; temporary file for input to diff.
+;; As written, checks whether this is an ange-ftp file.  It may be modified
+;; for customization.
+(defun emerge-remote-file-p ()
+  (and (boundp 'ange-ftp-path-format)
+       ange-ftp-path-format
+       (string-match (car ange-ftp-path-format) buffer-file-name)))
+
+;; Utilities that might have value outside of Emerge.
+
+;; Set up the mode in the current buffer to duplicate the mode in another
+;; buffer.
+(defun emerge-copy-modes (buffer)
+  ;; Set the major mode
+  (funcall (emerge-eval-in-buffer buffer major-mode)))
+
+;; Define a key, even if a prefix of it is defined
+(defun emerge-force-define-key (keymap key definition)
+  "Like `define-key', but forcibly creates prefix characters as needed.
+If some prefix of KEY has a non-prefix definition, it is redefined."
+  ;; Find out if a prefix of key is defined
+  (let ((v (lookup-key keymap key)))
+    ;; If so, undefine it
+    (if (integerp v)
+	(define-key keymap (substring key 0 v) nil)))
+  ;; Now define the key
+  (define-key keymap key definition))
+
+;; XEmacs -- nuked a bunch of junk here that provides a newer version
+;; of `describe-mode' that describes minor modes as well as the major
+;; mode.  We have this code standardly.
+
+;; Show the name of the file in the buffer.
+(defun emerge-show-file-name ()
+  "Displays the name of the file loaded into the current buffer.
+If the name won't fit on one line, the minibuffer is expanded to hold it,
+and the command waits for a keystroke from the user.  If the keystroke is
+SPC, it is ignored\; if it is anything else, it is processed as a command."
+  (interactive)
+  (let ((name (buffer-file-name)))
+    (or name
+	(setq name "Buffer has no file name."))
+    (save-window-excursion
+      (select-window (minibuffer-window))
+      (erase-buffer)
+      (insert name)
+      (if (not (pos-visible-in-window-p))
+	  (let ((echo-keystrokes 0))
+	    (while (and (not (pos-visible-in-window-p))
+			(> (1- (screen-height)) (window-height)))
+	      (enlarge-window 1))
+	    (if emerge-xemacs-p
+		(let ((e (next-command-event)))
+		  (if (not (eq 32 (event-to-character e)))
+		      (setq unread-command-event e)))
+                (let ((c (read-event)))
+                  (if (not (eq c 32))
+                      (setq unread-command-events (list c))))))))))
+
+;; Improved auto-save file names.
+;; This function fixes many problems with the standard auto-save file names:
+;; Auto-save files for non-file buffers get put in the default directory
+;; for the buffer, whether that makes sense or not.
+;; Auto-save files for file buffers get put in the directory of the file,
+;; regardless of whether we can write into it or not.
+;; Auto-save files for non-file buffers don't use the process id, so if a
+;; user runs more than on Emacs, they can make auto-save files that overwrite
+;; each other.
+;; To use this function, do:
+;;	(fset 'make-auto-save-file-name
+;;	      (symbol-function 'emerge-make-auto-save-file-name))
+(defun emerge-make-auto-save-file-name ()
+  "Return file name to use for auto-saves of current buffer.
+Does not consider `auto-save-visited-file-name';
+that is checked before calling this function.
+You can redefine this for customization.
+See also `auto-save-file-name-p'."
+  (if buffer-file-name
+      ;; if buffer has a file, try the format <file directory>/#<file name>#
+      (let ((f (concat (file-name-directory buffer-file-name)
+		       "#"
+		       (file-name-nondirectory buffer-file-name)
+		       "#")))
+	(if (file-writable-p f)
+	    ;; the file is writable, so use it
+	    f
+	  ;; the file isn't writable, so use the format
+	  ;; ~/#&<file name>&<hash of directory>#
+	  (concat (getenv "HOME")
+		  "/#&"
+		  (file-name-nondirectory buffer-file-name)
+		  "&"
+		  (emerge-hash-string-into-string
+		   (file-name-directory buffer-file-name))
+		  "#")))
+    ;; if buffer has no file, use the format ~/#%<buffer name>%<process id>#
+    (expand-file-name (concat (getenv "HOME")
+			      "/#%"
+			      ;; quote / into \! and \ into \\
+			      (emerge-unslashify-name (buffer-name))
+			      "%"
+			      (make-temp-name "")
+			      "#"))))
+
+;; Hash a string into five characters more-or-less suitable for use in a file
+;; name.  (Allowed characters are ! through ~, except /.)
+(defun emerge-hash-string-into-string (s)
+  (let ((bins (vector 0 0 0 0 0))
+	(i 0))
+    (while (< i (length s))
+      (aset bins (% i 5) (% (+ (* (aref bins (% i 5)) 35)
+			       (aref s i))
+			    65536))
+      (setq i (1+ i)))
+    (mapconcat (function (lambda (b)
+			   (setq b (+ (% b 93) ?!))
+			   (if (>= b ?/)
+			       (setq b (1+ b)))
+			   (char-to-string b)))
+	       bins "")))
+
+;; Quote any /s in a string by replacing them with \!.
+;; Also, replace any \s by \\, to make it one-to-one.
+(defun emerge-unslashify-name (s)
+  (let ((limit 0))
+    (while (string-match "[/\\]" s limit)
+      (setq s (concat (substring s 0 (match-beginning 0))
+		      (if (string= (substring s (match-beginning 0)
+					      (match-end 0))
+				   "/")
+			  "\\!"
+			"\\\\")
+		      (substring s (match-end 0))))
+      (setq limit (1+ (match-end 0)))))
+  s)
+
+;; Metacharacters that have to be protected from the shell when executing
+;; a diff/diff3 command.
+(defvar emerge-metachars "[ \t\n!\"#$&'()*;<=>?[\\^`{|~]"
+  "Characters that must be quoted with \\ when used in a shell command line.
+More precisely, a [...] regexp to match any one such character.")
+
+;; Quote metacharacters (using \) when executing a diff/diff3 command.
+(defun emerge-protect-metachars (s)
+  (let ((limit 0))
+    (while (string-match emerge-metachars s limit)
+      (setq s (concat (substring s 0 (match-beginning 0))
+		      "\\"
+		      (substring s (match-beginning 0))))
+      (setq limit (1+ (match-end 0)))))
+  s)
+
+(provide 'emerge)
+
+;;; emerge.el ends here