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;;; files.el --- file input and output commands for Emacs

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;; Copyright (C) 1985, 1986, 1987, 1992, 1993 Free Software Foundation, Inc.
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;; Maintainer: FSF

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;; This file is part of GNU Emacs.

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

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

;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs; see the file COPYING.  If not, write to
;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.

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;;; Commentary:

;; Defines most of Emacs's file- and directory-handling functions,
;; including basic file visiting, backup generation, link handling,
;; ITS-id version control, load- and write-hook handling, and the like.

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;;; Code:

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(defconst delete-auto-save-files t
  "*Non-nil means delete a buffer's auto-save file when the buffer is saved.")

(defconst directory-abbrev-alist
  nil
  "*Alist of abbreviations for file directories.
A list of elements of the form (FROM . TO), each meaning to replace
FROM with TO when it appears in a directory name.  This replacement is
done when setting up the default directory of a newly visited file.
*Every* FROM string should start with `^'.

Use this feature when you have directories which you normally refer to
via absolute symbolic links.  Make TO the name of the link, and FROM
the name it is linked to.")

;;; Turn off backup files on VMS since it has version numbers.
(defconst make-backup-files (not (eq system-type 'vax-vms))
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  "*Non-nil means make a backup of a file the first time it is saved.
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This can be done by renaming the file or by copying.

Renaming means that Emacs renames the existing file so that it is a
backup file, then writes the buffer into a new file.  Any other names
that the old file had will now refer to the backup file.  The new file
is owned by you and its group is defaulted.

Copying means that Emacs copies the existing file into the backup
file, then writes the buffer on top of the existing file.  Any other
names that the old file had will now refer to the new (edited) file.
The file's owner and group are unchanged.

The choice of renaming or copying is controlled by the variables
`backup-by-copying', `backup-by-copying-when-linked' and
`backup-by-copying-when-mismatch'.")

;; Do this so that local variables based on the file name
;; are not overridden by the major mode.
(defvar backup-inhibited nil
  "Non-nil means don't make a backup file for this buffer.")
(put 'backup-inhibited 'permanent-local t)

(defconst backup-by-copying nil
 "*Non-nil means always use copying to create backup files.
See documentation of variable `make-backup-files'.")

(defconst backup-by-copying-when-linked nil
 "*Non-nil means use copying to create backups for files with multiple names.
This causes the alternate names to refer to the latest version as edited.
This variable is relevant only if `backup-by-copying' is nil.")

(defconst backup-by-copying-when-mismatch nil
  "*Non-nil means create backups by copying if this preserves owner or group.
Renaming may still be used (subject to control of other variables)
when it would not result in changing the owner or group of the file;
that is, for files which are owned by you and whose group matches
the default for a new file created there by you.
This variable is relevant only if `backup-by-copying' is nil.")

(defvar backup-enable-predicate
  '(lambda (name)
     (or (< (length name) 5)
	 (not (string-equal "/tmp/" (substring name 0 5)))))
  "Predicate that looks at a file name and decides whether to make backups.
Called with an absolute file name as argument, it returns t to enable backup.")

(defconst buffer-offer-save nil
  "*Non-nil in a buffer means offer to save the buffer on exit
even if the buffer is not visiting a file.
Automatically local in all buffers.")
(make-variable-buffer-local 'buffer-offer-save)

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(defconst find-file-existing-other-name nil
  "*Non-nil means find a file under alternative names, in existing buffers.
This means if any existing buffer is visiting the file you want
under another name, you get the existing buffer instead of a new buffer.")

(defconst find-file-visit-truename nil
  "*Non-nil means visit a file under its truename.
The truename of a file is found by chasing all links
both at the file level and at the levels of the containing directories.")

(defvar buffer-file-truename nil
  "The truename of the file visited in the current buffer.
This variable is automatically local in all buffers, when non-nil.")
(make-variable-buffer-local 'buffer-file-truename)
(put 'buffer-file-truename 'permanent-local t)

(defvar buffer-file-number nil
  "The device number and file number of the file visited in the current buffer.
The value is a list of the form (FILENUM DEVNUM).
This pair of numbers uniquely identifies the file.
If the buffer is visiting a new file, the value is nil.")
(make-variable-buffer-local 'buffer-file-number)
(put 'buffer-file-number 'permanent-local t)

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(defconst file-precious-flag nil
  "*Non-nil means protect against I/O errors while saving files.
Some modes set this non-nil in particular buffers.")

(defvar version-control nil
  "*Control use of version numbers for backup files.
t means make numeric backup versions unconditionally.
nil means make them for files that have some already.
never means do not make them.")

(defvar dired-kept-versions 2
  "*When cleaning directory, number of versions to keep.")

(defvar trim-versions-without-asking nil
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  "*If t, deletes excess backup versions silently.
If nil, asks confirmation.  Any other value prevents any trimming.")
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(defvar kept-old-versions 2
  "*Number of oldest versions to keep when a new numbered backup is made.")

(defvar kept-new-versions 2
  "*Number of newest versions to keep when a new numbered backup is made.
Includes the new backup.  Must be > 0")

(defconst require-final-newline nil
  "*Value of t says silently ensure a file ends in a newline when it is saved.
Non-nil but not t says ask user whether to add a newline when there isn't one.
nil means don't add newlines.")

(defconst auto-save-default t
  "*Non-nil says by default do auto-saving of every file-visiting buffer.")

(defconst auto-save-visited-file-name nil
  "*Non-nil says auto-save a buffer in the file it is visiting, when practical.
Normally auto-save files are written under other names.")

(defconst save-abbrevs nil
  "*Non-nil means save word abbrevs too when files are saved.
Loading an abbrev file sets this to t.")

(defconst find-file-run-dired t
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  "*Non-nil says run dired if `find-file' is given the name of a directory.")
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;;;It is not useful to make this a local variable.
;;;(put 'find-file-not-found-hooks 'permanent-local t)
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(defvar find-file-not-found-hooks nil
  "List of functions to be called for `find-file' on nonexistent file.
These functions are called as soon as the error is detected.
`buffer-file-name' is already set up.
The functions are called in the order given until one of them returns non-nil.")

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;;;It is not useful to make this a local variable.
;;;(put 'find-file-hooks 'permanent-local t)
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(defvar find-file-hooks nil
  "List of functions to be called after a buffer is loaded from a file.
The buffer's local variables (if any) will have been processed before the
functions are called.")

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;;; In case someone does make it local.
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(put 'write-file-hooks 'permanent-local t)
(defvar write-file-hooks nil
  "List of functions to be called before writing out a buffer to a file.
If one of them returns non-nil, the file is considered already written
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and the rest are not called.
These hooks are considered to pertain to the visited file.
So this list is cleared if you change the visited file name.
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See also `write-contents-hooks'.
Don't make this variable buffer-local; instead, use `local-write-file-hooks'.")

(put 'local-write-file-hooks 'permanent-local t)
(defvar local-write-file-hooks nil
  "Just like `write-file-hooks', except intended for per-buffer use.
The functions in this list are called before the ones in
`write-file-hooks'.")
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(defvar write-contents-hooks nil
  "List of functions to be called before writing out a buffer to a file.
If one of them returns non-nil, the file is considered already written
and the rest are not called.
These hooks are considered to pertain to the buffer's contents,
not to the particular visited file; thus, `set-visited-file-name' does
not clear this variable, but changing the major mode does clear it.
See also `write-file-hooks'.")
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(defconst enable-local-variables t
  "*Control use of local-variables lists in files you visit.
The value can be t, nil or something else.
A value of t means local-variables lists are obeyed;
nil means they are ignored; anything else means query.

The command \\[normal-mode] always obeys local-variables lists
and ignores this variable.")

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(defconst enable-local-eval 'maybe
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  "*Control processing of the \"variable\" `eval' in a file's local variables.
The value can be t, nil or something else.
A value of t means obey `eval' variables;
nil means ignore them; anything else means query.

The command \\[normal-mode] always obeys local-variables lists
and ignores this variable.")
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;; Avoid losing in versions where CLASH_DETECTION is disabled.
(or (fboundp 'lock-buffer)
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    (defalias 'lock-buffer 'ignore))
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(or (fboundp 'unlock-buffer)
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    (defalias 'unlock-buffer 'ignore))
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(defun pwd ()
  "Show the current default directory."
  (interactive nil)
  (message "Directory %s" default-directory))

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(defvar cd-path nil
  "Value of the CDPATH environment variable, as a list.
Not actually set up until the first time you you use it.")

(defun parse-colon-path (cd-path)
  "Explode a colon-separated list of paths into a string list."
  (and cd-path
       (let (cd-prefix cd-list (cd-start 0) cd-colon)
	 (setq cd-path (concat cd-path ":"))
	 (while (setq cd-colon (string-match ":" cd-path cd-start))
	   (setq cd-list
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		 (nconc cd-list
			(list (substitute-in-file-name
			       (file-name-as-directory
				(substring cd-path cd-start cd-colon))))))
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	   (setq cd-start (+ cd-colon 1)))
	 cd-list)))

(defun cd-absolute (dir)
  "Change current directory to given absolute path DIR."
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  (interactive "DChange default directory: ")
  (setq dir (expand-file-name dir))
  (if (not (eq system-type 'vax-vms))
      (setq dir (file-name-as-directory dir)))
  (if (not (file-directory-p dir))
      (error "%s is not a directory" dir)
    (if (file-executable-p dir)
	(setq default-directory dir)
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      (error "Cannot cd to %s:  Permission denied" dir))))
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(defun cd (dir)
  "Make DIR become the current buffer's default directory.
If your environment imcludes a $CDPATH variable, cd tries each one of that
colon-separated list of directories when resolving a relative cd."
  (interactive "FChange default directory: ")
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  (let ((first (aref dir 0)))
    (if (or (= first ?/) (= first ?~))
	(cd-absolute (expand-file-name dir))
      (if (null cd-path)
	  (let ((trypath (parse-colon-path (getenv "CDPATH"))))
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	    (setq cd-path (or trypath (list "./")))))
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      (if (not (catch 'found
		 (mapcar
		  (function (lambda (x)
			      (let ((f (expand-file-name (concat x dir))))
				(if (file-directory-p f)
				    (progn
				      (cd-absolute f)
				      (throw 'found t))))))
		  cd-path)
		 nil))
	  (error "No such directory on your cd path.")))
    ))
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(defun load-file (file)
  "Load the Lisp file named FILE."
  (interactive "fLoad file: ")
  (load (expand-file-name file) nil nil t))

(defun load-library (library)
  "Load the library named LIBRARY.
This is an interface to the function `load'."
  (interactive "sLoad library: ")
  (load library))
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;; OTHER is the other file to be compared.
(defun file-local-copy (file)
  "Copy the file FILE into a temporary file on this machine.
Returns the name of the local copy, or nil, if FILE is directly
accessible."
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  (let ((handler (find-file-name-handler file)))
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    (if handler
	(funcall handler 'file-local-copy file)
      nil)))
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(defun file-truename (filename)
  "Return the truename of FILENAME, which should be absolute.
The truename of a file name is found by chasing symbolic links
both at the level of the file and at the level of the directories
containing it, until no links are left at any level."
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  (if (string= filename "~")
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      (progn
	(setq filename (expand-file-name filename))
	(if (string= filename "")
	    (setq filename "/"))))
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  (let ((handler (find-file-name-handler filename)))
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    ;; For file name that has a special handler, call handler.
    ;; This is so that ange-ftp can save time by doing a no-op.
    (if handler
	(funcall handler 'file-truename filename)
      (let ((dir (file-name-directory filename))
	    target dirfile)
	;; Get the truename of the directory.
	(setq dirfile (directory-file-name dir))
	;; If these are equal, we have the (or a) root directory.
	(or (string= dir dirfile)
	    (setq dir (file-name-as-directory (file-truename dirfile))))
	;; Put it back on the file name.
	(setq filename (concat dir (file-name-nondirectory filename)))
	;; Is the file name the name of a link?
	(setq target (file-symlink-p filename))
	(if target
	    ;; Yes => chase that link, then start all over
	    ;; since the link may point to a directory name that uses links.
	    (file-truename (expand-file-name target dir))
	  ;; No, we are done!
	  filename)))))
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(defun file-chase-links (filename)
  "Chase links in FILENAME until a name that is not a link.
Does not examine containing directories for links,
unlike `file-truename'."
  (let (tem (count 100) (newname filename))
    (while (setq tem (file-symlink-p newname))
      (if (= count 0)
	  (error "Apparent cycle of symbolic links for %s" filename))
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      ;; Handle `..' by hand, since it needs to work in the
      ;; target of any directory symlink.
      ;; This code is not quite complete; it does not handle
      ;; embedded .. in some cases such as ./../foo and foo/bar/../../../lose.
      (while (string-match "\\.\\./" tem)
	(setq tem (substring tem 3))
	(setq newname (file-name-as-directory
		       ;; Do the .. by hand.
		       (directory-file-name
			(file-name-directory
			 ;; Chase links in the default dir of the symlink.
			 (file-chase-links
			  (directory-file-name
			   (file-name-directory newname))))))))
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      (setq newname (expand-file-name tem (file-name-directory newname)))
      (setq count (1- count)))
    newname))
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(defun switch-to-buffer-other-window (buffer)
  "Select buffer BUFFER in another window."
  (interactive "BSwitch to buffer in other window: ")
  (let ((pop-up-windows t))
    (pop-to-buffer buffer t)))

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(defun switch-to-buffer-other-frame (buffer)
  "Switch to buffer BUFFER in another frame."
  (interactive "BSwitch to buffer in other frame: ")
  (let ((pop-up-frames t))
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    (pop-to-buffer buffer t)))
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(defun find-file (filename)
  "Edit file FILENAME.
Switch to a buffer visiting file FILENAME,
creating one if none already exists."
  (interactive "FFind file: ")
  (switch-to-buffer (find-file-noselect filename)))

(defun find-file-other-window (filename)
  "Edit file FILENAME, in another window.
May create a new window, or reuse an existing one.
See the function `display-buffer'."
  (interactive "FFind file in other window: ")
  (switch-to-buffer-other-window (find-file-noselect filename)))

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(defun find-file-other-frame (filename)
  "Edit file FILENAME, in another frame.
May create a new frame, or reuse an existing one.
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See the function `display-buffer'."
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  (interactive "FFind file in other frame: ")
  (switch-to-buffer-other-frame (find-file-noselect filename)))
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(defun find-file-read-only (filename)
  "Edit file FILENAME but don't allow changes.
Like \\[find-file] but marks buffer as read-only.
Use \\[toggle-read-only] to permit editing."
  (interactive "fFind file read-only: ")
  (find-file filename)
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  (setq buffer-read-only t)
  (current-buffer))
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(defun find-file-read-only-other-window (filename)
  "Edit file FILENAME in another window but don't allow changes.
Like \\[find-file-other-window] but marks buffer as read-only.
Use \\[toggle-read-only] to permit editing."
  (interactive "fFind file read-only other window: ")
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  (find-file-other-window filename)
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  (setq buffer-read-only t)
  (current-buffer))
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(defun find-file-read-only-other-frame (filename)
  "Edit file FILENAME in another frame but don't allow changes.
Like \\[find-file-other-frame] but marks buffer as read-only.
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Use \\[toggle-read-only] to permit editing."
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  (interactive "fFind file read-only other frame: ")
  (find-file-other-frame filename)
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  (setq buffer-read-only t)
  (current-buffer))
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(defun find-alternate-file (filename)
  "Find file FILENAME, select its buffer, kill previous buffer.
If the current buffer now contains an empty file that you just visited
\(presumably by mistake), use this command to visit the file you really want."
  (interactive
   (let ((file buffer-file-name)
	 (file-name nil)
	 (file-dir nil))
     (and file
	  (setq file-name (file-name-nondirectory file)
		file-dir (file-name-directory file)))
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     (list (read-file-name
	    "Find alternate file: " file-dir nil nil file-name))))
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  (and (buffer-modified-p)
       ;; (not buffer-read-only)
       (not (yes-or-no-p (format "Buffer %s is modified; kill anyway? "
				 (buffer-name))))
       (error "Aborted"))
  (let ((obuf (current-buffer))
	(ofile buffer-file-name)
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	(onum buffer-file-number)
	(otrue buffer-file-truename)
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	(oname (buffer-name)))
    (rename-buffer " **lose**")
    (setq buffer-file-name nil)
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    (setq buffer-file-number nil)
    (setq buffer-file-truename nil)
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    (unwind-protect
	(progn
	  (unlock-buffer)
	  (find-file filename))
      (cond ((eq obuf (current-buffer))
	     (setq buffer-file-name ofile)
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	     (setq buffer-file-number onum)
	     (setq buffer-file-truename otrue)
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	     (lock-buffer)
	     (rename-buffer oname))))
    (or (eq (current-buffer) obuf)
	(kill-buffer obuf))))

(defun create-file-buffer (filename)
  "Create a suitably named buffer for visiting FILENAME, and return it.
FILENAME (sans directory) is used unchanged if that name is free;
otherwise a string <2> or <3> or ... is appended to get an unused name."
  (let ((lastname (file-name-nondirectory filename)))
    (if (string= lastname "")
	(setq lastname filename))
    (generate-new-buffer lastname)))

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(defun generate-new-buffer (name)
  "Create and return a buffer with a name based on NAME.
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Choose the buffer's name using `generate-new-buffer-name'."
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  (get-buffer-create (generate-new-buffer-name name)))

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(defconst automount-dir-prefix "^/tmp_mnt/"
  "Regexp to match the automounter prefix in a directory name.")

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(defvar abbreviated-home-dir nil
  "The the user's homedir abbreviated according to `directory-abbrev-list'.")

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(defun abbreviate-file-name (filename)
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  "Return a version of FILENAME shortened using `directory-abbrev-alist'.
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This also substitutes \"~\" for the user's home directory.
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Type \\[describe-variable] directory-abbrev-alist RET for more information."
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  ;; Get rid of the prefixes added by the automounter.
  (if (and (string-match automount-dir-prefix filename)
	   (file-exists-p (file-name-directory
			   (substring filename (1- (match-end 0))))))
      (setq filename (substring filename (1- (match-end 0)))))
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  (let ((tail directory-abbrev-alist))
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    ;; If any elt of directory-abbrev-alist matches this name,
    ;; abbreviate accordingly.
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    (while tail
      (if (string-match (car (car tail)) filename)
	  (setq filename
		(concat (cdr (car tail)) (substring filename (match-end 0)))))
      (setq tail (cdr tail)))
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    ;; Compute and save the abbreviated homedir name.
    ;; We defer computing this until the first time it's needed, to
    ;; give time for directory-abbrev-alist to be set properly.
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    ;; We include a slash at the end, to avoid spurious matches
    ;; such as `/usr/foobar' when the home dir is `/usr/foo'.
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    (or abbreviated-home-dir
	(setq abbreviated-home-dir
	      (let ((abbreviated-home-dir "$foo"))
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		(concat "^" (abbreviate-file-name (expand-file-name "~/"))))))
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    ;; If FILENAME starts with the abbreviated homedir,
    ;; make it start with `~' instead.
    (if (string-match abbreviated-home-dir filename)
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	(setq filename
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	      (concat "~"
		      ;; If abbreviated-home-dir ends with a slash,
		      ;; don't remove the corresponding slash from
		      ;; filename.  On MS-DOS and OS/2, you can have
		      ;; home directories like "g:/", in which it is
		      ;; important not to remove the slash.  And what
		      ;; about poor root on Unix systems?
		      (if (eq ?/ (aref abbreviated-home-dir
				       (1- (length abbreviated-home-dir))))
			  "/"
			"")
		      (substring filename (match-end 0)))))
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    filename))

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(defvar find-file-not-true-dirname-list nil
  "*List of logical names for which visiting shouldn't save the true dirname.
On VMS, when you visit a file using a logical name that searches a path,
you may or may not want the visited file name to record the specific
directory where the file was found.  If you *do not* want that, add the logical
name to this list as a string.")

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(defun find-file-noselect (filename &optional nowarn)
  "Read file FILENAME into a buffer and return the buffer.
If a buffer exists visiting FILENAME, return that one, but
verify that the file has not changed since visited or saved.
The buffer is not selected, just returned to the caller."
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  (setq filename
	(abbreviate-file-name
	 (expand-file-name filename)))
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  (if (file-directory-p filename)
      (if find-file-run-dired
	  (dired-noselect filename)
	(error "%s is a directory." filename))
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    (let* ((buf (get-file-buffer filename))
	   (truename (abbreviate-file-name (file-truename filename)))
	   (number (nthcdr 10 (file-attributes truename)))
	   ;; Find any buffer for a file which has same truename.
	   (same-truename
	    (or buf ; Shortcut
		(let (found
		      (list (buffer-list)))
		  (while (and (not found) list)
		    (save-excursion
		      (set-buffer (car list))
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		      (if (and buffer-file-name
			       (string= buffer-file-truename truename))
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			(setq found (car list))))
		    (setq list (cdr list)))
		  found)))
	   (same-number
	    (or buf ; Shortcut
		(and number
		     (let (found
			   (list (buffer-list)))
		       (while (and (not found) list)
			 (save-excursion
			   (set-buffer (car list))
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			   (if (and (equal buffer-file-number number)
				    ;; Verify this buffer's file number
				    ;; still belongs to its file.
				    (file-exists-p buffer-file-name)
				    (equal (nthcdr 10 (file-attributes buffer-file-name)) number))
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			     (setq found (car list))))
			 (setq list (cdr list)))
		       found))))
	   error)
      ;; Let user know if there is a buffer with the same truename.
      (if (and (not buf) same-truename (not nowarn))
	  (message "%s and %s are the same file (%s)"
		   filename (buffer-file-name same-truename)
		   truename)
	(if (and (not buf) same-number (not nowarn))
	  (message "%s and %s are the same file"
		   filename (buffer-file-name same-number))))

      ;; Optionally also find that buffer.
      (if (or find-file-existing-other-name find-file-visit-truename)
	  (setq buf (or same-truename same-number)))
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      (if buf
	  (or nowarn
	      (verify-visited-file-modtime buf)
	      (cond ((not (file-exists-p filename))
		     (error "File %s no longer exists!" filename))
		    ((yes-or-no-p
		      (format
		       (if (buffer-modified-p buf)
    "File %s changed on disk.  Discard your edits? "
    "File %s changed on disk.  Read the new version? ")
		       (file-name-nondirectory filename)))
		     (save-excursion
		       (set-buffer buf)
		       (revert-buffer t t)))))
	(save-excursion
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;;; The truename stuff makes this obsolete.
;;;	  (let* ((link-name (car (file-attributes filename)))
;;;		 (linked-buf (and (stringp link-name)
;;;				  (get-file-buffer link-name))))
;;;	    (if (bufferp linked-buf)
;;;		(message "Symbolic link to file in buffer %s"
;;;			 (buffer-name linked-buf))))
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	  (setq buf (create-file-buffer filename))
	  (set-buffer buf)
	  (erase-buffer)
	  (condition-case ()
	      (insert-file-contents filename t)
	    (file-error
	     (setq error t)
	     ;; Run find-file-not-found-hooks until one returns non-nil.
	     (let ((hooks find-file-not-found-hooks))
	       (while (and hooks
			   (not (funcall (car hooks))))
		 (setq hooks (cdr hooks))))))
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	  ;; Find the file's truename, and maybe use that as visited name.
	  (setq buffer-file-truename (abbreviate-file-name truename))
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	  (setq buffer-file-number number)
	  ;; On VMS, we may want to remember which directory in a search list
	  ;; the file was found in.
	  (and (eq system-type 'vax-vms)
	       (let (logical)
		 (if (string-match ":" (file-name-directory filename))
		     (setq logical (substring (file-name-directory filename)
					      0 (match-beginning 0))))
		 (not (member logical find-file-not-true-dirname-list)))
	       (setq buffer-file-name buffer-file-truename))
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	  (if find-file-visit-truename
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	      (setq buffer-file-name
		    (setq filename
			  (expand-file-name buffer-file-truename))))
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	  ;; Set buffer's default directory to that of the file.
	  (setq default-directory (file-name-directory filename))
	  ;; Turn off backup files for certain file names.  Since
	  ;; this is a permanent local, the major mode won't eliminate it.
	  (and (not (funcall backup-enable-predicate buffer-file-name))
	       (progn
		 (make-local-variable 'backup-inhibited)
		 (setq backup-inhibited t)))
	  (after-find-file error (not nowarn))))
      buf)))

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(defun after-find-file (&optional error warn noauto)
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  "Called after finding a file and by the default revert function.
Sets buffer mode, parses local variables.
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Optional args ERROR, WARN, and NOAUTO: ERROR non-nil means there was an
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error in reading the file.  WARN non-nil means warn if there
exists an auto-save file more recent than the visited file.
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NOAUTO means don't mess with auto-save mode.
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Finishes by calling the functions in `find-file-hooks'."
  (setq buffer-read-only (not (file-writable-p buffer-file-name)))
  (if noninteractive
      nil
    (let* (not-serious
	   (msg
	    (cond ((and error (file-attributes buffer-file-name))
		   (setq buffer-read-only t)
		   "File exists, but is read-protected.")
		  ((not buffer-read-only)
		   (if (and warn
			    (file-newer-than-file-p (make-auto-save-file-name)
						    buffer-file-name))
		       "Auto save file is newer; consider M-x recover-file"
		     (setq not-serious t)
		     (if error "(New file)" nil)))
		  ((not error)
		   (setq not-serious t)
		   "Note: file is write protected")
		  ((file-attributes (directory-file-name default-directory))
		   "File not found and directory write-protected")
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		  ((file-exists-p (file-name-directory buffer-file-name))
		   (setq buffer-read-only nil))
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		  (t
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		   (setq buffer-read-only nil)
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		   (if (file-exists-p (file-name-directory (directory-file-name (file-name-directory buffer-file-name))))
		       "Use M-x make-dir RET RET to create the directory"
		     "Use C-u M-x make-dir RET RET to create directory and its parents")))))
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      (if msg
	  (progn
	    (message msg)
	    (or not-serious (sit-for 1 nil t)))))
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    (if (and auto-save-default (not noauto))
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	(auto-save-mode t)))
  (normal-mode t)
  (mapcar 'funcall find-file-hooks))

(defun normal-mode (&optional find-file)
  "Choose the major mode for this buffer automatically.
Also sets up any specified local variables of the file.
Uses the visited file name, the -*- line, and the local variables spec.

This function is called automatically from `find-file'.  In that case,
we may set up specified local variables depending on the value of
`enable-local-variables': if it is t, we do; if it is nil, we don't;
otherwise, we query.  `enable-local-variables' is ignored if you
run `normal-mode' explicitly."
  (interactive)
  (or find-file (funcall (or default-major-mode 'fundamental-mode)))
  (condition-case err
      (set-auto-mode)
    (error (message "File mode specification error: %s"
		    (prin1-to-string err))))
  (condition-case err
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      (let ((enable-local-variables (or (not find-file)
					enable-local-variables)))
	(hack-local-variables))
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    (error (message "File local-variables error: %s"
		    (prin1-to-string err)))))

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(defvar auto-mode-alist (mapcar 'purecopy
				'(("\\.text\\'" . text-mode)
				  ("\\.c\\'" . c-mode)
				  ("\\.h\\'" . c-mode)
				  ("\\.tex\\'" . TeX-mode)
				  ("\\.ltx\\'" . LaTeX-mode)
				  ("\\.el\\'" . emacs-lisp-mode)
				  ("\\.mm\\'" . nroff-mode)
				  ("\\.me\\'" . nroff-mode)
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				  ("\\.ms\\'" . nroff-mode)
				  ("\\.man\\'" . nroff-mode)
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				  ("\\.scm\\'" . scheme-mode)
				  ("\\.l\\'" . lisp-mode)
				  ("\\.lisp\\'" . lisp-mode)
				  ("\\.f\\'" . fortran-mode)
				  ("\\.for\\'" . fortran-mode)
				  ("\\.mss\\'" . scribe-mode)
				  ("\\.pl\\'" . prolog-mode)
				  ("\\.cc\\'" . c++-mode)
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				  ("\\.hh\\'" . c++-mode)
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				  ("\\.C\\'" . c++-mode)
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				  ("\\.H\\'" . c++-mode)
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;;;				  ("\\.mk\\'" . makefile-mode)
;;;				  ("[Mm]akefile" . makefile-mode)
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;;; Less common extensions come here
;;; so more common ones above are found faster.
				  ("\\.s\\'" . asm-mode)
				  ("ChangeLog\\'" . change-log-mode)
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				  ("ChangeLog.[0-9]+\\'" . change-log-mode)
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				  ("\\$CHANGE_LOG\\$\\.TXT" . change-log-mode)
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;; The following should come after the ChangeLog pattern
;; for the sake of ChangeLog.1, etc.
				  ("\\.[12345678]\\'" . nroff-mode)
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				  ("\\.TeX\\'" . TeX-mode)
				  ("\\.sty\\'" . LaTeX-mode)
				  ("\\.bbl\\'" . LaTeX-mode)
				  ("\\.bib\\'" . bibtex-mode)
				  ("\\.article\\'" . text-mode)
				  ("\\.letter\\'" . text-mode)
				  ("\\.texinfo\\'" . texinfo-mode)
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				  ("\\.texi\\'" . texinfo-mode)
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				  ("\\.lsp\\'" . lisp-mode)
				  ("\\.awk\\'" . awk-mode)
				  ("\\.prolog\\'" . prolog-mode)
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				  ("\\.tar\\'" . tar-mode)
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				  ;; Mailer puts message to be edited in
				  ;; /tmp/Re.... or Message
				  ("^/tmp/Re" . text-mode)
				  ("/Message[0-9]*\\'" . text-mode)
				  ;; some news reader is reported to use this
				  ("^/tmp/fol/" . text-mode)
				  ("\\.y\\'" . c-mode)
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				  ("\\.lex\\'" . c-mode)
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				  ("\\.oak\\'" . scheme-mode)
				  ("\\.scm.[0-9]*\\'" . scheme-mode)
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				  ("\\.sgm\\'" . sgml-mode)
				  ("\\.sgml\\'" . sgml-mode)
				  ("\\.dtd\\'" . sgml-mode)
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				  ;; .emacs following a directory delimiter
				  ;; in either Unix or VMS syntax.
				  ("[]>:/]\\..*emacs\\'" . emacs-lisp-mode)
				  ("\\.ml\\'" . lisp-mode)))
  "\
Alist of filename patterns vs corresponding major mode functions.
Each element looks like (REGEXP . FUNCTION).
Visiting a file whose name matches REGEXP causes FUNCTION to be called.")

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(defconst inhibit-local-variables-regexps '("\\.tar$")
  "List of regexps; if one matches a file name, don't look for local vars.")

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(defun set-auto-mode ()
  "Select major mode appropriate for current buffer.
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This checks for a -*- mode tag in the buffer's text, or
compares the filename against the entries in auto-mode-alist.  It does
not check for the \"mode:\" local variable in the Local Variables
section of the file; for that, use `hack-local-variables'.

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If `enable-local-variables' is nil, this function does not check for a
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-*- mode tag."
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  ;; Look for -*-MODENAME-*- or -*- ... mode: MODENAME; ... -*-
  (let (beg end mode)
    (save-excursion
      (goto-char (point-min))
      (skip-chars-forward " \t\n")
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      (if (and enable-local-variables
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	       ;; Don't look for -*- if this file name matches any
	       ;; of the regexps in inhibit-local-variables-regexps.
	       (not (let ((temp inhibit-local-variables-regexps))
		      (while (and temp
				  (not (string-match (car temp)
						     buffer-file-name)))
			(setq temp (cdr temp)))
		      (not temp)))
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	       (search-forward "-*-" (save-excursion
				       ;; If the file begins with "#!"
				       ;; (exec interpreter magic), look
				       ;; for mode frobs in the first two
				       ;; lines.  You cannot necessarily
				       ;; put them in the first line of
				       ;; such a file without screwing up
				       ;; the interpreter invocation.
				       (end-of-line (and (looking-at "^#!") 2))
				       (point)) t)
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	       (progn
		 (skip-chars-forward " \t")
		 (setq beg (point))
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		 (search-forward "-*-"
				 (save-excursion (end-of-line) (point))
				 t))
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	       (progn
		 (forward-char -3)
		 (skip-chars-backward " \t")
		 (setq end (point))
		 (goto-char beg)
		 (if (search-forward ":" end t)
		     (progn
		       (goto-char beg)
		       (if (let ((case-fold-search t))
			     (search-forward "mode:" end t))
			   (progn
			     (skip-chars-forward " \t")
			     (setq beg (point))
			     (if (search-forward ";" end t)
				 (forward-char -1)
			       (goto-char end))
			     (skip-chars-backward " \t")
			     (setq mode (buffer-substring beg (point))))))
		   (setq mode (buffer-substring beg end)))))
	  (setq mode (intern (concat (downcase mode) "-mode")))
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	(if buffer-file-name
	    (let ((alist auto-mode-alist)
		  (name buffer-file-name))
	      (let ((case-fold-search (eq system-type 'vax-vms)))
		;; Remove backup-suffixes from file name.
		(setq name (file-name-sans-versions name))
		;; Find first matching alist entry.
		(while (and (not mode) alist)
		  (if (string-match (car (car alist)) name)
		      (setq mode (cdr (car alist))))
		  (setq alist (cdr alist))))))))
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    (if mode (funcall mode))))

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(defun hack-local-variables-prop-line ()
  ;; Set local variables specified in the -*- line.
  ;; Returns t if mode was set.
  (save-excursion
    (goto-char (point-min))
    (skip-chars-forward " \t\n\r")
    (let ((result '())
	  (end (save-excursion (end-of-line) (point)))
	  mode-p)
      ;; Parse the -*- line into the `result' alist.
      (cond ((not (search-forward "-*-" end t))
	     ;; doesn't have one.
	     nil)
	    ((looking-at "[ \t]*\\([^ \t\n\r:;]+\\)\\([ \t]*-\\*-\\)")
	     ;; Simple form: "-*- MODENAME -*-".
	     (setq result
	       (list (cons 'mode
			   (intern (buffer-substring
				    (match-beginning 1)
				    (match-end 1)))))))
	    (t
	     ;; Hairy form: '-*-' [ <variable> ':' <value> ';' ]* '-*-'
	     ;; (last ";" is optional).
	     (save-excursion
	       (if (search-forward "-*-" end t)
		   (setq end (- (point) 3))
		 (error "-*- not terminated before end of line")))
	     (while (< (point) end)
	       (or (looking-at "[ \t]*\\([^ \t\n:]+\\)[ \t]*:[ \t]*")
		   (error "malformed -*- line"))
	       (goto-char (match-end 0))
	       (let ((key (intern (downcase (buffer-substring
					     (match-beginning 1)
					     (match-end 1)))))
		     (val (save-restriction
			    (narrow-to-region (point) end)
			    (read (current-buffer)))))
		 (setq result (cons (cons key val) result))
		 (skip-chars-forward " \t;")))
	     (setq result (nreverse result))))

      ;; Mode is magic.
      (let (mode)
	(while (setq mode (assq 'mode result))
	  (setq mode-p t result (delq mode result))
	  (funcall (intern (concat (downcase (symbol-name (cdr mode)))
				   "-mode")))))
      
      (if (and result
	       (or (eq enable-local-variables t)
		   (and enable-local-variables
			(save-window-excursion
			  (switch-to-buffer (current-buffer))
			  (y-or-n-p (format "Set local variables as specified in -*- line of %s? "
					    (file-name-nondirectory buffer-file-name)))))))
	  (while result
	    (let ((key (car (car result)))
		  (val (cdr (car result))))
	      ;; 'mode has already been removed from this list.
	      (hack-one-local-variable key val))
	    (setq result (cdr result))))
      mode-p)))

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(defun hack-local-variables ()
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  "Parse and put into effect this buffer's local variables spec."
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  (hack-local-variables-prop-line)
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  ;; Look for "Local variables:" line in last page.
  (save-excursion
    (goto-char (point-max))
    (search-backward "\n\^L" (max (- (point-max) 3000) (point-min)) 'move)
    (if (let ((case-fold-search t))
	  (and (search-forward "Local Variables:" nil t)
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	       (or (eq enable-local-variables t)
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		   (and enable-local-variables
			(save-window-excursion
			  (switch-to-buffer (current-buffer))
			  (save-excursion
			    (beginning-of-line)
			    (set-window-start (selected-window) (point)))
			  (y-or-n-p (format "Set local variables as specified at end of %s? "
					    (file-name-nondirectory buffer-file-name))))))))
	(let ((continue t)
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	      prefix prefixlen suffix beg
	      (enable-local-eval enable-local-eval))
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	  ;; The prefix is what comes before "local variables:" in its line.
	  ;; The suffix is what comes after "local variables:" in its line.
	  (skip-chars-forward " \t")
	  (or (eolp)
	      (setq suffix (buffer-substring (point)
					     (progn (end-of-line) (point)))))
	  (goto-char (match-beginning 0))
	  (or (bolp)
	      (setq prefix
		    (buffer-substring (point)
				      (progn (beginning-of-line) (point)))))
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	  (if prefix (setq prefixlen (length prefix)
			   prefix (regexp-quote prefix)))
	  (if suffix (setq suffix (concat (regexp-quote suffix) "$")))
	  (while continue
	    ;; Look at next local variable spec.
	    (if selective-display (re-search-forward "[\n\C-m]")
	      (forward-line 1))
	    ;; Skip the prefix, if any.
	    (if prefix
		(if (looking-at prefix)
		    (forward-char prefixlen)
		  (error "Local variables entry is missing the prefix")))
	    ;; Find the variable name; strip whitespace.
	    (skip-chars-forward " \t")
	    (setq beg (point))
	    (skip-chars-forward "^:\n")
	    (if (eolp) (error "Missing colon in local variables entry"))
	    (skip-chars-backward " \t")
	    (let* ((str (buffer-substring beg (point)))
		   (var (read str))
		  val)
	      ;; Setting variable named "end" means end of list.
	      (if (string-equal (downcase str) "end")
		  (setq continue nil)
		;; Otherwise read the variable value.
		(skip-chars-forward "^:")
		(forward-char 1)
		(setq val (read (current-buffer)))
		(skip-chars-backward "\n")
		(skip-chars-forward " \t")
		(or (if suffix (looking-at suffix) (eolp))
		    (error "Local variables entry is terminated incorrectly"))
		;; Set the variable.  "Variables" mode and eval are funny.
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		(hack-one-local-variable var val))))))))

(defconst ignored-local-variables
  '(enable-local-eval)
  "Variables to be ignored in a file's local variable spec.")

;; "Set" one variable in a local variables spec.
;; A few variable names are treated specially.
(defun hack-one-local-variable (var val)
  (cond ((eq var 'mode)
	 (funcall (intern (concat (downcase (symbol-name val))
				  "-mode"))))
	((memq var ignored-local-variables)
	 nil)
	;; "Setting" eval means either eval it or do nothing.
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	;; Likewise for setting hook variables.
	((or (eq var 'eval)
	     (string-match "-hooks?$\\|-functions?$" (symbol-name var)))
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	 (if (and (not (string= (user-login-name) "root"))
		  (or (eq enable-local-eval t)
		      (and enable-local-eval
			   (save-window-excursion
			     (switch-to-buffer (current-buffer))
			     (save-excursion
			       (beginning-of-line)
			       (set-window-start (selected-window) (point)))
			     (setq enable-local-eval
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				   (y-or-n-p (format "Process `eval' or hook local variables in file %s? "
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						     (file-name-nondirectory buffer-file-name))))))))
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	     (if (eq var 'eval)
		 (save-excursion (eval val))
	       (make-local-variable var)
	       (set var val))
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	   (message "Ignoring `eval:' in file's local variables")))
	;; Ordinary variable, really set it.
	(t (make-local-variable var)
	   (set var val))))

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(defun set-visited-file-name (filename)
  "Change name of file visited in current buffer to FILENAME.
The next time the buffer is saved it will go in the newly specified file.
nil or empty string as argument means make buffer not be visiting any file.
Remember to delete the initial contents of the minibuffer
if you wish to pass an empty string as the argument."
  (interactive "FSet visited file name: ")
  (if filename
      (setq filename
	    (if (string-equal filename "")
		nil
	      (expand-file-name filename))))
  (or (equal filename buffer-file-name)
      (null filename)
      (progn
	(lock-buffer filename)
	(unlock-buffer)))
  (setq buffer-file-name filename)
  (if filename				; make buffer name reflect filename.
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      (let ((new-name (file-name-nondirectory buffer-file-name)))
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	(if (string= new-name "")
	    (error "Empty file name"))
	(if (eq system-type 'vax-vms)
	    (setq new-name (downcase new-name)))
	(setq default-directory (file-name-directory buffer-file-name))
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	(rename-buffer new-name t)))
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  (setq buffer-backed-up nil)
  (clear-visited-file-modtime)
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  (if filename
      (progn
	(setq buffer-file-truename
	      (abbreviate-file-name (file-truename buffer-file-name)))
	(if find-file-visit-truename
	    (setq buffer-file-name buffer-file-truename))
	(setq buffer-file-number (nth 10 (file-attributes buffer-file-name))))
    (setq buffer-file-truename nil buffer-file-number nil))
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  ;; write-file-hooks is normally used for things like ftp-find-file
  ;; that visit things that are not local files as if they were files.
  ;; Changing to visit an ordinary local file instead should flush the hook.
  (kill-local-variable 'write-file-hooks)
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  (kill-local-variable 'local-write-file-hooks)
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  (kill-local-variable 'revert-buffer-function)
  (kill-local-variable 'backup-inhibited)
  ;; Turn off backup files for certain file names.
  ;; Since this is a permanent local, the major mode won't eliminate it.
  (and (not (funcall backup-enable-predicate buffer-file-name))
       (progn
	 (make-local-variable 'backup-inhibited)
	 (setq backup-inhibited t)))
  ;; If auto-save was not already on, turn it on if appropriate.
  (if (not buffer-auto-save-file-name)
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      (and buffer-file-name auto-save-default
	   (auto-save-mode t))
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    ;; If auto save is on, start using a new name.
    ;; We deliberately don't rename or delete the old auto save
    ;; for the old visited file name.  This is because perhaps
    ;; the user wants to save the new state and then compare with the
    ;; previous state from the auto save file.
    (setq buffer-auto-save-file-name
	  (make-auto-save-file-name)))
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  (if buffer-file-name
      (set-buffer-modified-p t)))

(defun write-file (filename)
  "Write current buffer into file FILENAME.
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Makes buffer visit that file, and marks it not modified.
If the buffer is already visiting a file, you can specify
a directory name as FILENAME, to write a file of the same
old name in that directory."
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;;  (interactive "FWrite file: ")
  (interactive
   (list (if buffer-file-name
	     (read-file-name "Write file: "
				 nil nil nil nil)
	   (read-file-name "Write file: "
			       (cdr (assq 'default-directory
					  (buffer-local-variables)))
			       nil nil (buffer-name)))))
  (or (null filename) (string-equal filename "")
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      (progn
	;; If arg is just a directory,
	;; use same file name, but in that directory.
	(if (and (file-directory-p filename) buffer-file-name)
	    (setq filename (concat (file-name-as-directory filename)
				   (file-name-nondirectory buffer-file-name))))
	(set-visited-file-name filename)))
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  (set-buffer-modified-p t)
  (save-buffer))

(defun backup-buffer ()
  "Make a backup of the disk file visited by the current buffer, if appropriate.
This is normally done before saving the buffer the first time.
If the value is non-nil, it is the result of `file-modes' on the original
file; this means that the caller, after saving the buffer, should change
the modes of the new file to agree with the old modes."
  (if (and make-backup-files (not backup-inhibited)
	   (not buffer-backed-up)
	   (file-exists-p buffer-file-name)
	   (memq (aref (elt (file-attributes buffer-file-name) 8) 0)
		 '(?- ?l)))
      (let ((real-file-name buffer-file-name)
	    backup-info backupname targets setmodes)
	;; If specified name is a symbolic link, chase it to the target.
	;; Thus we make the backups in the directory where the real file is.
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	(setq real-file-name (file-chase-links real-file-name))
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	(setq backup-info (find-backup-file-name real-file-name)
	      backupname (car backup-info)
	      targets (cdr backup-info))
;;;     (if (file-directory-p buffer-file-name)
;;;         (error "Cannot save buffer in directory %s" buffer-file-name))
        (condition-case ()
	    (let ((delete-old-versions
		   ;; If have old versions to maybe delete,
		   ;; ask the user to confirm now, before doing anything.
		   ;; But don't actually delete til later.
		   (and targets
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			(or (eq trim-versions-without-asking t) (eq trim-versions-without-asking nil))
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			(or trim-versions-without-asking
			    (y-or-n-p (format "Delete excess backup versions of %s? "
					      real-file-name))))))
	      ;; Actually write the back up file.
	      (condition-case ()
		  (if (or file-precious-flag
;			  (file-symlink-p buffer-file-name)
			  backup-by-copying
			  (and backup-by-copying-when-linked
			       (> (file-nlinks real-file-name) 1))
			  (and backup-by-copying-when-mismatch
			       (let ((attr (file-attributes real-file-name)))
				 (or (nth 9 attr)
				     (/= (nth 2 attr) (user-uid))))))
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		      (condition-case ()
			  (copy-file real-file-name backupname t t)
			(file-error
			 ;; If copying fails because file BACKUPNAME
			 ;; is not writable, delete that file and try again.
			 (if (and (file-exists-p backupname)
				  (not (file-writable-p backupname)))
			     (delete-file backupname))
			 (copy-file real-file-name backupname t t)))
		    ;; rename-file should delete old backup.
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		    (rename-file real-file-name backupname t)
		    (setq setmodes (file-modes backupname)))
		(file-error
		 ;; If trouble writing the backup, write it in ~.
		 (setq backupname (expand-file-name "~/%backup%~"))
		 (message "Cannot write backup file; backing up in ~/%%backup%%~")
		 (sleep-for 1)
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		 (condition-case ()
		     (copy-file real-file-name backupname t t)
		   (file-error
		    ;; If copying fails because file BACKUPNAME
		    ;; is not writable, delete that file and try again.
		    (if (and (file-exists-p backupname)
			     (not (file-writable-p backupname)))
			(delete-file backupname))
		    (copy-file real-file-name backupname t t)))))
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	      (setq buffer-backed-up t)
	      ;; Now delete the old versions, if desired.
	      (if delete-old-versions
		  (while targets
		    (condition-case ()
			(delete-file (car targets))
		      (file-error nil))
		    (setq targets (cdr targets))))
	      setmodes)
	(file-error nil)))))

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(defun file-name-sans-versions (name &optional keep-backup-version)
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  "Return FILENAME sans backup versions or strings.
This is a separate procedure so your site-init or startup file can
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redefine it.
If the optional argument KEEP-BACKUP-VERSION is non-nil,
we do not remove backup version numbers, only true file version numbers."
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  (let ((handler (find-file-name-handler name)))
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    (if handler
	(funcall handler 'file-name-sans-versions name keep-backup-version)
      (substring name 0
		 (if (eq system-type 'vax-vms)
		     ;; VMS version number is (a) semicolon, optional
		     ;; sign, zero or more digits or (b) period, option
		     ;; sign, zero or more digits, provided this is the
		     ;; second period encountered outside of the
		     ;; device/directory part of the file name.
		     (or (string-match ";[---+]?[0-9]*\\'" name)
			 (if (string-match "\\.[^]>:]*\\(\\.[---+]?[0-9]*\\)\\'"
					   name)
			     (match-beginning 1))
			 (length name))
		   (if keep-backup-version
		       (length name)
		     (or (string-match "\\.~[0-9]+~\\'" name)
			 (string-match "~\\'" name)
			 (length name))))))))
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(defun make-backup-file-name (file)
  "Create the non-numeric backup file name for FILE.
This is a separate function so you can redefine it for customization."
  (concat file "~"))

(defun backup-file-name-p (file)
  "Return non-nil if FILE is a backup file name (numeric or not).
This is a separate function so you can redefine it for customization.
You may need to redefine `file-name-sans-versions' as well."
  (string-match "~$" file))

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;; This is used in various files.
;; The usage of bv-length is not very clean,
;; but I can't see a good alternative,
;; so as of now I am leaving it alone.
(defun backup-extract-version (fn)
  "Given the name of a numeric backup file, return the backup number.
Uses the free variable `bv-length', whose value should be
the index in the name where the version number begins."
  (if (and (string-match "[0-9]+~$" fn bv-length)
	   (= (match-beginning 0) bv-length))
      (string-to-int (substring fn bv-length -1))
      0))

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;; I believe there is no need to alter this behavior for VMS;
;; since backup files are not made on VMS, it should not get called.
(defun find-backup-file-name (fn)
  "Find a file name for a backup file, and suggestions for deletions.
Value is a list whose car is the name for the backup file
 and whose cdr is a list of old versions to consider deleting now."
  (if (eq version-control 'never)
      (list (make-backup-file-name fn))
    (let* ((base-versions (concat (file-name-nondirectory fn) ".~"))
	   (bv-length (length base-versions))
	   (possibilities (file-name-all-completions
			   base-versions
			   (file-name-directory fn)))
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	   (versions (sort (mapcar
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			    (function backup-extract-version)
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			    possibilities)
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			   '<))
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	   (high-water-mark (apply 'max 0 versions))
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	   (deserve-versions-p
	    (or version-control
		(> high-water-mark 0)))
	   (number-to-delete (- (length versions)
				kept-old-versions kept-new-versions -1)))
      (if (not deserve-versions-p)
	  (list (make-backup-file-name fn))
	(cons (concat fn ".~" (int-to-string (1+ high-water-mark)) "~")
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	      (if (and (> number-to-delete 0)
                       ;; Delete nothing if there is overflow
		       ;; in the number of versions to keep.
		       (>= (+ kept-new-versions kept-old-versions -1) 0))
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		  (mapcar (function (lambda (n)
				      (concat fn ".~" (int-to-string n) "~")))
			  (let ((v (nthcdr kept-old-versions versions)))
			    (rplacd (nthcdr (1- number-to-delete) v) ())
			    v))))))))

(defun file-nlinks (filename)
  "Return number of names file FILENAME has."
  (car (cdr (file-attributes filename))))
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(defun file-relative-name-1 (directory)
  (cond ((string= directory "/")
	 filename)
	((string-match (concat "^" (regexp-quote directory))
		       filename)
	 (substring filename (match-end 0)))
	(t
	 (file-relative-name-1
	  (file-name-directory (substring directory 0 -1))))))

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(defun file-relative-name (filename &optional directory)
  "Convert FILENAME to be relative to DIRECTORY (default: default-directory)."
  (setq filename (expand-file-name filename)
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	directory (file-name-as-directory (if directory
					      (expand-file-name directory)
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					      default-directory)))
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  (file-relative-name-1 directory))
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(defun save-buffer (&optional args)
  "Save current buffer in visited file if modified.  Versions described below.
By default, makes the previous version into a backup file
 if previously requested or if this is the first save.
With 1 or 3 \\[universal-argument]'s, marks this version
 to become a backup when the next save is done.
With 2 or 3 \\[universal-argument]'s,
 unconditionally makes the previous version into a backup file.
With argument of 0, never makes the previous version into a backup file.

If a file's name is FOO, the names of its numbered backup versions are
 FOO.~i~ for various integers i.  A non-numbered backup file is called FOO~.
Numeric backups (rather than FOO~) will be made if value of
 `version-control' is not the atom `never' and either there are already
 numeric versions of the file being backed up, or `version-control' is
 non-nil.
We don't want excessive versions piling up, so there are variables
 `kept-old-versions', which tells Emacs how many oldest versions to keep,
 and `kept-new-versions', which tells how many newest versions to keep.
 Defaults are 2 old versions and 2 new.
`dired-kept-versions' controls dired's clean-directory (.) command.
If `trim-versions-without-asking' is nil, system will query user
 before trimming versions.  Otherwise it does it silently."
  (int