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;;; info.el --- info package for Emacs
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;; Copyright (C) 1985, 86, 92, 93, 94, 95, 96, 97, 98, 99, 2000, 2001, 2002
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;;  Free Software Foundation, Inc.
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;; Maintainer: FSF
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;; Keywords: help
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;; This file is part of GNU Emacs.

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

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

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

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;; Note that nowadays we expect info files to be made using makeinfo.
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;;; Code:

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(eval-when-compile (require 'jka-compr))

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(defgroup info nil
  "Info subsystem"
  :group 'help
  :group 'docs)


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(defvar Info-history nil
  "List of info nodes user has visited.
Each element of list is a list (FILENAME NODENAME BUFFERPOS).")

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(defcustom Info-enable-edit nil
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  "*Non-nil means the \\<Info-mode-map>\\[Info-edit] command in Info can edit the current node.
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This is convenient if you want to write info files by hand.
However, we recommend that you not do this.
It is better to write a Texinfo file and generate the Info file from that,
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because that gives you a printed manual as well."
  :type 'boolean
  :group 'info)
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(defvar Info-enable-active-nodes nil
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  "Non-nil allows Info to execute Lisp code associated with nodes.
The Lisp code is executed when the node is selected.")
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(put 'Info-enable-active-nodes 'risky-local-variable t)
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(defface info-node
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  '((((class color) (background light)) (:foreground "brown" :weight bold :slant italic))
    (((class color) (background dark)) (:foreground "white" :weight bold :slant italic))
    (t (:weight bold :slant italic)))
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  "Face for Info node names."
  :group 'info)

(defface info-menu-5
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  '((((class color)) (:foreground "red1"))
    (t (:underline t)))
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  "Face for every third `*' in an Info menu."
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  :group 'info)

(defface info-xref
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  '((((class color) (background light)) (:foreground "magenta4" :weight bold))
    (((class color) (background dark)) (:foreground "cyan" :weight bold))
    (t (:weight bold)))
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  "Face for Info cross-references."
  :group 'info)

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(defcustom Info-fontify-maximum-menu-size 100000
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  "*Maximum size of menu to fontify if `font-lock-mode' is non-nil."
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  :type 'integer
  :group 'info)
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(defcustom Info-use-header-line t
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  "*Non-nil means to put the beginning-of-node links in an Emacs header-line.
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A header-line does not scroll with the rest of the buffer."
  :type 'boolean
  :group 'info)

(defface info-header-xref
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  '((t (:inherit info-xref)))
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  "Face for Info cross-references in a node header."
  :group 'info)

(defface info-header-node
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  '((t (:inherit info-node)))
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  "Face for Info nodes in a node header."
  :group 'info)

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(defvar Info-directory-list nil
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  "List of directories to search for Info documentation files.
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If nil, meaning not yet initialized, Info uses the environment
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variable INFOPATH to initialize it, or `Info-default-directory-list'
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if there is no INFOPATH variable in the environment.
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When `Info-directory-list' is initialized from the value of
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`Info-default-directory-list', and Emacs is installed in one of the
standard directories, the directory of Info files that come with Emacs
is put last (so that local Info files override standard ones).

When `Info-directory-list' is initialized from the value of
`Info-default-directory-list', and Emacs is not installed in one
of the standard directories, the first element of the resulting
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list is the directory where Emacs installs the Info files that
come with it.  This is so that Emacs's own manual, which suits the
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version of Emacs you are using, will always be found first.  This
is useful when you install an experimental version of Emacs without
removing the standard installation.

If you want to override the order of directories in
`Info-default-directory-list', set INFOPATH in the environment.
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If you run the Emacs executable from the `src' directory in the Emacs
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source tree, and INFOPATH is not defined, the `info' directory in the
source tree is used as the first element of `Info-directory-list', in
place of the installation Info directory.  This is useful when you run
a version of Emacs without installing it.")
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(defcustom Info-additional-directory-list nil
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  "List of additional directories to search for Info documentation files.
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These directories are searched after those in `Info-directory-list'."
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  :type '(repeat directory)
  :group 'info)
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(defcustom Info-scroll-prefer-subnodes t
  "*If non-nil, \\<Info-mode-map>\\[Info-scroll-up] in a menu visits subnodes.
If this is non-nil, and you scroll far enough in a node that its menu
appears on the screen, the next \\<Info-mode-map>\\[Info-scroll-up]
moves to a subnode indicated by the following menu item.  This means
that you visit a subnode before getting to the end of the menu.

Setting this option to nil results in behavior similar to the stand-alone
Info reader program, which visits the first subnode from the menu only
when you hit the end of the current node."
  :type 'boolean
  :group 'info)

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(defcustom Info-hide-note-references t
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  "*If non-nil, hide the tag and section reference in *note and * menu items.
Also replaces the \"*note\" text with \"see\".
If value is a number, the reference section is still shown."
  :version "21.4"
  :type '(choice (const :tag "Replace tag and hide reference" t)
		 (const :tag "Replace only tag" tag)
		 (const :tag "No reformatting" nil))
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  :group 'info)

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(defcustom Info-mode-hook '(turn-on-font-lock)
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  "Hooks run when `info-mode' is called."
  :type 'hook
  :group 'info)

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(defvar Info-current-file nil
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  "Info file that Info is now looking at, or nil.
This is the name that was specified in Info, not the actual file name.
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It doesn't contain directory names or file name extensions added by Info.
Can also be t when using `Info-on-current-buffer'.")
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(defvar Info-current-subfile nil
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  "Info subfile that is actually in the *info* buffer now.
nil if current info file is not split into subfiles.")
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(defvar Info-current-node nil
  "Name of node that Info is now looking at, or nil.")

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(defvar Info-tag-table-marker nil
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  "Marker pointing at beginning of current Info file's tag table.
Marker points nowhere if file has no tag table.")

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(defvar Info-tag-table-buffer nil
  "Buffer used for indirect tag tables.")

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(defvar Info-current-file-completions nil
  "Cached completion list for current Info file.")

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(defvar Info-index-alternatives nil
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  "List of possible matches for last `Info-index' command.")
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(defvar Info-standalone nil
  "Non-nil if Emacs was started solely as an Info browser.")
190

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(defvar Info-suffix-list
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  ;; The MS-DOS list should work both when long file names are
  ;; supported (Windows 9X), and when only 8+3 file names are available.
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  (if (eq system-type 'ms-dos)
      '( (".gz"      . "gunzip")
	 (".z"       . "gunzip")
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	 (".bz2"     . ("bzip2" "-dc"))
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	 (".inz"     . "gunzip")
	 (".igz"     . "gunzip")
	 (".info.Z"  . "gunzip")
	 (".info.gz" . "gunzip")
	 ("-info.Z"  . "gunzip")
	 ("-info.gz" . "gunzip")
	 ("/index.gz". "gunzip")
	 ("/index.z" . "gunzip")
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	 (".inf"     . nil)
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	 (".info"    . nil)
	 ("-info"    . nil)
	 ("/index"   . nil)
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	 (""         . nil))
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    '( (".info.Z".    "uncompress")
       (".info.Y".    "unyabba")
       (".info.gz".   "gunzip")
       (".info.z".    "gunzip")
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       (".info.bz2" . ("bzip2" "-dc"))
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       (".info".      nil)
       ("-info.Z".   "uncompress")
       ("-info.Y".   "unyabba")
       ("-info.gz".  "gunzip")
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       ("-info.bz2" . ("bzip2" "-dc"))
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       ("-info.z".   "gunzip")
       ("-info".     nil)
       ("/index.Z".   "uncompress")
       ("/index.Y".   "unyabba")
       ("/index.gz".  "gunzip")
       ("/index.z".   "gunzip")
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       ("/index.bz2". ("bzip2" "-dc"))
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       ("/index".     nil)
       (".Z".         "uncompress")
       (".Y".         "unyabba")
       (".gz".        "gunzip")
       (".z".         "gunzip")
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       (".bz2" .      ("bzip2" "-dc"))
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       ("".           nil)))
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  "List of file name suffixes and associated decoding commands.
Each entry should be (SUFFIX . STRING); the file is given to
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the command as standard input.

STRING may be a list of strings.  In that case, the first element is
the command name, and the rest are arguments to that command.

If STRING is nil, no decoding is done.
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Because the SUFFIXes are tried in order, the empty string should
be last in the list.")
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;; Concatenate SUFFIX onto FILENAME.  SUFFIX should start with a dot.
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;; First, on MS-DOS with no long file names support, delete some of
;; the extension in FILENAME to make room.
(defun info-insert-file-contents-1 (filename suffix lfn)
  (if lfn	; long file names are supported
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      (concat filename suffix)
    (let* ((sans-exts (file-name-sans-extension filename))
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	   ;; How long is the extension in FILENAME (not counting the dot).
	   (ext-len (max 0 (- (length filename) (length sans-exts) 1)))
	   ext-left)
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      ;; SUFFIX starts with a dot.  If FILENAME already has one,
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      ;; get rid of the one in SUFFIX (unless suffix is empty).
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      (or (and (<= ext-len 0)
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	       (not (eq (aref filename (1- (length filename))) ?.)))
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	  (= (length suffix) 0)
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	  (setq suffix (substring suffix 1)))
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      ;; How many chars of that extension should we keep?
      (setq ext-left (min ext-len (max 0 (- 3 (length suffix)))))
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      ;; Get rid of the rest of the extension, and add SUFFIX.
      (concat (substring filename 0 (- (length filename)
				       (- ext-len ext-left)))
	      suffix))))

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(defun info-file-exists-p (filename)
  (and (file-exists-p filename)
       (not (file-directory-p filename))))

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(defun info-insert-file-contents (filename &optional visit)
  "Insert the contents of an info file in the current buffer.
Do the right thing if the file has been compressed or zipped."
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  (let* ((tail Info-suffix-list)
	 (lfn (or (not (fboundp 'msdos-long-file-names))
		  (msdos-long-file-names)))
	 (check-short (and (fboundp 'msdos-long-file-names)
			   lfn))
	 fullname decoder done)
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    (if (info-file-exists-p filename)
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	;; FILENAME exists--see if that name contains a suffix.
	;; If so, set DECODE accordingly.
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	(progn
	  (while (and tail
		      (not (string-match
			    (concat (regexp-quote (car (car tail))) "$")
			    filename)))
	    (setq tail (cdr tail)))
	  (setq fullname filename
		decoder (cdr (car tail))))
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      ;; Try adding suffixes to FILENAME and see if we can find something.
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      (while (and tail (not done))
	(setq fullname (info-insert-file-contents-1 filename
						    (car (car tail)) lfn))
	(if (info-file-exists-p fullname)
	    (setq done t
		  ;; If we found a file with a suffix, set DECODER
		  ;; according to the suffix.
		  decoder (cdr (car tail)))
	  ;; When the MS-DOS port runs on Windows, we need to check
	  ;; the short variant of a long file name as well.
	  (when check-short
	    (setq fullname (info-insert-file-contents-1 filename
							(car (car tail)) nil))
	    (if (info-file-exists-p fullname)
		(setq done t
		      decoder (cdr (car tail))))))
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	(setq tail (cdr tail)))
      (or tail
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	  (error "Can't find %s or any compressed version of it" filename)))
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    ;; check for conflict with jka-compr
    (if (and (featurep 'jka-compr)
	     (jka-compr-installed-p)
	     (jka-compr-get-compression-info fullname))
	(setq decoder nil))
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    (if decoder
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	(progn
	  (insert-file-contents-literally fullname visit)
	  (let ((buffer-read-only nil)
		(coding-system-for-write 'no-conversion)
		(default-directory (or (file-name-directory fullname)
				       default-directory)))
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	    (or (consp decoder)
		(setq decoder (list decoder)))
	    (apply 'call-process-region (point-min) (point-max)
		   (car decoder) t t nil (cdr decoder))))
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      (insert-file-contents fullname visit))))
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(defun info-initialize ()
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  "Initialize `Info-directory-list', if that hasn't been done yet."
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  (unless Info-directory-list
    (let ((path (getenv "INFOPATH"))
	  (source (expand-file-name "info/" source-directory))
	  (sibling (if installation-directory
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		       (expand-file-name "info/" installation-directory)
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		     (if invocation-directory
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			 (let ((infodir (expand-file-name
					 "../info/"
					 invocation-directory)))
			   (if (file-exists-p infodir)
			       infodir
			     (setq infodir (expand-file-name
					    "../../../info/"
					    invocation-directory))
			     (and (file-exists-p infodir)
				  infodir))))))
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	  alternative)
      (setq Info-directory-list
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	    (prune-directory-list
	     (if path
		 (split-string path (regexp-quote path-separator))
	       (if (and sibling (file-exists-p sibling))
		   ;; Uninstalled, Emacs builddir != srcdir.
		   (setq alternative sibling)
		 ;; Uninstalled, builddir == srcdir
		 (setq alternative source))
	       (if (or (member alternative Info-default-directory-list)
		       ;; On DOS/NT, we use movable executables always,
		       ;; and we must always find the Info dir at run time.
		       (if (memq system-type '(ms-dos windows-nt))
			   nil
			 ;; Use invocation-directory for Info
			 ;; only if we used it for exec-directory also.
			 (not (string= exec-directory
				       (expand-file-name "lib-src/"
							 installation-directory))))
		       (not (file-exists-p alternative)))
		   Info-default-directory-list
		 ;; `alternative' contains the Info files that came with this
		 ;; version, so we should look there first.  `Info-insert-dir'
		 ;; currently expects to find `alternative' first on the list.
		 (cons alternative
		       (reverse (cdr (reverse Info-default-directory-list)))))))))))
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;;;###autoload
(defun info-other-window (&optional file)
  "Like `info' but show the Info buffer in another window."
  (interactive (if current-prefix-arg
		   (list (read-file-name "Info file name: " nil nil t))))
  (let (same-window-buffer-names)
    (info file)))
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;;;###autoload (add-hook 'same-window-buffer-names "*info*")
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;;;###autoload
(defun info (&optional file)
  "Enter Info, the documentation browser.
Optional argument FILE specifies the file to examine;
the default is the top-level directory of Info.
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Called from a program, FILE may specify an Info node of the form
`(FILENAME)NODENAME'.
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In interactive use, a prefix argument directs this command
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to read a file name from the minibuffer.

The search path for Info files is in the variable `Info-directory-list'.
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The top-level Info directory is made by combining all the files named `dir'
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in all the directories in that path."
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  (interactive (if current-prefix-arg
		   (list (read-file-name "Info file name: " nil nil t))))
  (if file
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      (progn
	(pop-to-buffer "*info*")
	;; If argument already contains parentheses, don't add another set
	;; since the argument will then be parsed improperly.  This also
	;; has the added benefit of allowing node names to be included
	;; following the parenthesized filename.
	(if (and (stringp file) (string-match "(.*)" file))
	    (Info-goto-node file)
	  (Info-goto-node (concat "(" file ")"))))
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    (if (get-buffer "*info*")
	(pop-to-buffer "*info*")
      (Info-directory))))
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;;;###autoload
(defun info-emacs-manual ()
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  "Display the Emacs manual in Info mode."
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  (interactive)
  (info "emacs"))

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;;;###autoload
(defun info-standalone ()
  "Run Emacs as a standalone Info reader.
Usage:  emacs -f info-standalone [filename]
In standalone mode, \\<Info-mode-map>\\[Info-exit] exits Emacs itself."
  (setq Info-standalone t)
  (if (and command-line-args-left
	   (not (string-match "^-" (car command-line-args-left))))
      (condition-case err
	  (progn
	    (info (car command-line-args-left))
	    (setq command-line-args-left (cdr command-line-args-left)))
	(error (send-string-to-terminal
		(format "%s\n" (if (eq (car-safe err) 'error)
				   (nth 1 err) err)))
	       (save-buffers-kill-emacs)))
    (info)))
440

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;; See if the accessible portion of the buffer begins with a node
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;; delimiter, and the node header line which follows matches REGEXP.
;; Typically, this test will be followed by a loop that examines the
;; rest of the buffer with (search-forward "\n\^_"), and it's a pity
;; to have the overhead of this special test inside the loop.

;; This function changes match-data, but supposedly the caller might
;; want to use the results of re-search-backward.

;; The return value is the value of point at the beginning of matching
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;; REGEXP, if the function succeeds, nil otherwise.
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(defun Info-node-at-bob-matching (regexp)
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  (and (bobp)				; are we at beginning of buffer?
       (looking-at "\^_")		; does it begin with node delimiter?
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       (let (beg)
	 (forward-line 1)
	 (setq beg (point))
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	 (forward-line 1)		; does the line after delimiter match REGEXP?
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	 (re-search-backward regexp beg t))))

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(defun Info-find-node (filename nodename &optional no-going-back)
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  "Go to an info node specified as separate FILENAME and NODENAME.
NO-GOING-BACK is non-nil if recovering from an error in this function;
it says do not attempt further (recursive) error recovery."
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  (info-initialize)
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  ;; Convert filename to lower case if not found as specified.
  ;; Expand it.
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  (if (stringp filename)
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      (let (temp temp-downcase found)
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        (setq filename (substitute-in-file-name filename))
        (if (string= (downcase filename) "dir")
            (setq found t)
          (let ((dirs (if (string-match "^\\./" filename)
                          ;; If specified name starts with `./'
                          ;; then just try current directory.
                          '("./")
                        (if (file-name-absolute-p filename)
                            ;; No point in searching for an
                            ;; absolute file name
                            '(nil)
                          (if Info-additional-directory-list
                              (append Info-directory-list
                                      Info-additional-directory-list)
                            Info-directory-list)))))
            ;; Search the directory list for file FILENAME.
            (while (and dirs (not found))
              (setq temp (expand-file-name filename (car dirs)))
              (setq temp-downcase
                    (expand-file-name (downcase filename) (car dirs)))
              ;; Try several variants of specified name.
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              (let ((suffix-list Info-suffix-list)
		    (lfn (or (not (fboundp 'msdos-long-file-names))
			     (msdos-long-file-names))))
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                (while (and suffix-list (not found))
                  (cond ((info-file-exists-p
                          (info-insert-file-contents-1
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                           temp (car (car suffix-list)) lfn))
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                         (setq found temp))
                        ((info-file-exists-p
                          (info-insert-file-contents-1
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                           temp-downcase (car (car suffix-list)) lfn))
                         (setq found temp-downcase))
			((and (fboundp 'msdos-long-file-names)
			      lfn
			      (info-file-exists-p
			       (info-insert-file-contents-1
				temp (car (car suffix-list)) nil)))
			 (setq found temp)))
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                  (setq suffix-list (cdr suffix-list))))
              (setq dirs (cdr dirs)))))
        (if found
            (setq filename found)
          (error "Info file %s does not exist" filename))))
  ;; Record the node we are leaving.
  (if (and Info-current-file (not no-going-back))
      (setq Info-history
            (cons (list Info-current-file Info-current-node (point))
                  Info-history)))
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  ;; Go into info buffer.
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  (or (eq major-mode 'Info-mode) (pop-to-buffer "*info*"))
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  (Info-find-node-2 filename nodename no-going-back))

(defun Info-on-current-buffer (&optional nodename)
  "Use the `Info-mode' to browse the current info buffer.
If a prefix arg is provided, it queries for the NODENAME which
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else defaults to \"Top\"."
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  (interactive
   (list (if current-prefix-arg
	     (completing-read "Node name: " (Info-build-node-completions)
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			      nil t "Top"))))
  (unless nodename (setq nodename "Top"))
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  (info-initialize)
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  (Info-mode)
  (set (make-local-variable 'Info-current-file) t)
  (Info-find-node-2 nil nodename))

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(defun Info-find-in-tag-table-1 (marker regexp case-fold)
  "Find a node in a tag table.
MARKER specifies the buffer and position to start searching at.
REGEXP is a regular expression matching nodes or references.  Its first
group should match `Node:' or `Ref:'.
CASE-FOLD t means search for a case-insensitive match.
If a match was found, value is a list (FOUND-ANCHOR POS MODE), where
FOUND-ANCHOR is non-nil if a `Ref:' was matched, POS is the position
where the match was found, and MODE is `major-mode' of the buffer in
which the match was found."
  (let ((case-fold-search case-fold)
	found-mode guesspos found-anchor)
    (save-excursion
      (set-buffer (marker-buffer marker))
      (goto-char marker)
    
      ;; Search tag table
      (beginning-of-line)
      (when (re-search-forward regexp nil t)
	(list (string-equal "Ref:" (match-string 1))
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	      (+ (point-min) (read (current-buffer)))
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	      major-mode)))))

(defun Info-find-in-tag-table (marker regexp)
  "Find a node in a tag table.
MARKER specifies the buffer and position to start searching at.
REGEXP is a regular expression matching nodes or references.  Its first
group should match `Node:' or `Ref:'.
If a match was found, value is a list (FOUND-ANCHOR POS MODE), where
FOUND-ANCHOR is non-nil if a `Ref:' was matched, POS is the position
where the match was found, and MODE is `major-mode' of the buffer in
which the match was found.
This function tries to find a case-sensitive match first, then a
case-insensitive match is tried."
  (let ((result (Info-find-in-tag-table-1 marker regexp nil)))
    (when (null (car result))
      (setq result (Info-find-in-tag-table-1 marker regexp t)))
    result))

(defun Info-find-node-in-buffer-1 (regexp case-fold)
  "Find a node or anchor in the current buffer.
REGEXP is a regular expression matching nodes or references.  Its first
group should match `Node:' or `Ref:'.
CASE-FOLD t means search for a case-insensitive match.
Value is the position at which a match was found, or nil if not found."
  (let ((case-fold-search case-fold)
	found)
    (save-excursion
      (when (Info-node-at-bob-matching regexp)
	(setq found (point)))
      (while (and (not found)
		  (search-forward "\n\^_" nil t))
	(forward-line 1)
	(let ((beg (point)))
	  (forward-line 1)
	  (when (re-search-backward regexp beg t)
	    (beginning-of-line)
	    (setq found (point)))))
      found)))
		  
(defun Info-find-node-in-buffer (regexp)
  "Find a node or anchor in the current buffer.
REGEXP is a regular expression matching nodes or references.  Its first
group should match `Node:' or `Ref:'.
Value is the position at which a match was found, or nil if not found.
This function looks for a case-sensitive match first.  If none is found,
a case-insensitive match is tried."
  (or (Info-find-node-in-buffer-1 regexp nil)
      (Info-find-node-in-buffer-1 regexp t)))
  
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(defun Info-find-node-2 (filename nodename &optional no-going-back)
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  (buffer-disable-undo (current-buffer))
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  (or (eq major-mode 'Info-mode)
      (Info-mode))
  (widen)
  (setq Info-current-node nil)
  (unwind-protect
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      (let ((case-fold-search t)
	    anchorpos)
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        ;; Switch files if necessary
        (or (null filename)
            (equal Info-current-file filename)
            (let ((buffer-read-only nil))
              (setq Info-current-file nil
                    Info-current-subfile nil
                    Info-current-file-completions nil
                    buffer-file-name nil)
              (erase-buffer)
              (if (eq filename t)
                  (Info-insert-dir)
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                (info-insert-file-contents filename nil)
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                (setq default-directory (file-name-directory filename)))
              (set-buffer-modified-p nil)
              ;; See whether file has a tag table.  Record the location if yes.
              (goto-char (point-max))
              (forward-line -8)
              ;; Use string-equal, not equal, to ignore text props.
              (if (not (or (string-equal nodename "*")
                           (not
                            (search-forward "\^_\nEnd tag table\n" nil t))))
                  (let (pos)
                    ;; We have a tag table.  Find its beginning.
                    ;; Is this an indirect file?
                    (search-backward "\nTag table:\n")
                    (setq pos (point))
                    (if (save-excursion
                          (forward-line 2)
                          (looking-at "(Indirect)\n"))
                        ;; It is indirect.  Copy it to another buffer
                        ;; and record that the tag table is in that buffer.
                        (let ((buf (current-buffer))
                              (tagbuf
                               (or Info-tag-table-buffer
                                   (generate-new-buffer " *info tag table*"))))
                          (setq Info-tag-table-buffer tagbuf)
                          (save-excursion
                            (set-buffer tagbuf)
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                            (buffer-disable-undo (current-buffer))
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                            (setq case-fold-search t)
                            (erase-buffer)
                            (insert-buffer-substring buf))
                          (set-marker Info-tag-table-marker
                                      (match-end 0) tagbuf))
                      (set-marker Info-tag-table-marker pos)))
                (set-marker Info-tag-table-marker nil))
              (setq Info-current-file
                    (if (eq filename t) "dir" filename))))
        ;; Use string-equal, not equal, to ignore text props.
        (if (string-equal nodename "*")
            (progn (setq Info-current-node nodename)
                   (Info-set-mode-line))
          ;; Possibilities:
          ;;
          ;; 1. Anchor found in tag table
          ;; 2. Anchor *not* in tag table
          ;;
          ;; 3. Node found in tag table
          ;; 4. Node *not* found in tag table, but found in file
          ;; 5. Node *not* in tag table, and *not* in file
          ;;
          ;; *Or* the same, but in an indirect subfile.

          ;; Search file for a suitable node.
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	  (let ((guesspos (point-min))
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		(regexp (concat "\\(Node:\\|Ref:\\) *\\("
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				(if (stringp nodename)
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				    (regexp-quote nodename)
				  "")
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				"\\) *[,\t\n\177]"))
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		(nodepos nil))
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	    (catch 'foo
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	      ;; First, search a tag table, if any
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	      (when (marker-position Info-tag-table-marker)
		(let* ((m Info-tag-table-marker)
		       (found (Info-find-in-tag-table m regexp)))
		  
		  (when found
		    ;; FOUND is (ANCHOR POS MODE).
		    (setq guesspos (nth 1 found))
		    
		    ;; If this is an indirect file, determine which
		    ;; file really holds this node and read it in.
		    (unless (eq (nth 2 found) 'Info-mode)
		      ;; Note that the current buffer must be the
		      ;; *info* buffer on entry to
		      ;; Info-read-subfile.  Thus the hackery above.
		      (setq guesspos (Info-read-subfile guesspos)))
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		    ;; Handle anchor
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		    (when (nth 0 found)
		      (goto-char (setq anchorpos guesspos))
		      (throw 'foo t)))))
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	      ;; Else we may have a node, which we search for:
	      (goto-char (max (point-min)
			      (- (byte-to-position guesspos) 1000)))
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	      ;; Now search from our advised position (or from beg of
	      ;; buffer) to find the actual node.  First, check
	      ;; whether the node is right where we are, in case the
	      ;; buffer begins with a node.
	      (let ((pos (Info-find-node-in-buffer regexp)))
		(when pos
		  (goto-char pos)
		  (throw 'foo t))
		(error "No such anchor in tag table or node in tag table or file: %s"
		       nodename)))
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	    (Info-select-node)
	    (goto-char (or anchorpos (point-min))))))
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    ;; If we did not finish finding the specified node,
    ;; go back to the previous one.
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    (or Info-current-node no-going-back (null Info-history)
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        (let ((hist (car Info-history)))
          (setq Info-history (cdr Info-history))
          (Info-find-node (nth 0 hist) (nth 1 hist) t)
          (goto-char (nth 2 hist))))))
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;; Cache the contents of the (virtual) dir file, once we have merged
;; it for the first time, so we can save time subsequently.
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(defvar Info-dir-contents nil)

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;; Cache for the directory we decided to use for the default-directory
;; of the merged dir text.
(defvar Info-dir-contents-directory nil)

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;; Record the file attributes of all the files from which we
;; constructed Info-dir-contents.
(defvar Info-dir-file-attributes nil)

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(defvar Info-dir-file-name nil)

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;; Construct the Info directory node by merging the files named `dir'
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;; from various directories.  Set the *info* buffer's
;; default-directory to the first directory we actually get any text
;; from.
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(defun Info-insert-dir ()
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  (if (and Info-dir-contents Info-dir-file-attributes
	   ;; Verify that none of the files we used has changed
	   ;; since we used it.
	   (eval (cons 'and
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		       (mapcar (lambda (elt)
				 (let ((curr (file-attributes
					      ;; Handle symlinks
					      (file-truename (car elt)))))

				   ;; Don't compare the access time.
				   (if curr (setcar (nthcdr 4 curr) 0))
				   (setcar (nthcdr 4 (cdr elt)) 0)
				   (equal (cdr elt) curr)))
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			       Info-dir-file-attributes))))
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      (progn
	(insert Info-dir-contents)
	(goto-char (point-min)))
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    (let ((dirs (if Info-additional-directory-list
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		    (append Info-directory-list
			    Info-additional-directory-list)
		  Info-directory-list))
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	  (dir-file-attrs nil)
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	  ;; Bind this in case the user sets it to nil.
	  (case-fold-search t)
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	  ;; This is set non-nil if we find a problem in some input files.
	  problems
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	  buffers buffer others nodes dirs-done)
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      ;; Search the directory list for the directory file.
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      (while dirs
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	(let ((truename (file-truename (expand-file-name (car dirs)))))
	  (or (member truename dirs-done)
	      (member (directory-file-name truename) dirs-done)
	      ;; Try several variants of specified name.
	      ;; Try upcasing, appending `.info', or both.
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	      (let* (file
		     (attrs
		      (or
		       (progn (setq file (expand-file-name "dir" truename))
			      (file-attributes file))
		       (progn (setq file (expand-file-name "DIR" truename))
			      (file-attributes file))
		       (progn (setq file (expand-file-name "dir.info" truename))
			      (file-attributes file))
		       (progn (setq file (expand-file-name "DIR.INFO" truename))
			      (file-attributes file)))))
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		(setq dirs-done
		      (cons truename
			    (cons (directory-file-name truename)
				  dirs-done)))
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		(if attrs
		    (save-excursion
		      (or buffers
			  (message "Composing main Info directory..."))
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		      (set-buffer (generate-new-buffer " info dir"))
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		      (condition-case nil
			  (progn
			    (insert-file-contents file)
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			    (set (make-local-variable 'Info-dir-file-name)
				 file)
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			    (push (current-buffer) buffers)
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			    (push (cons file attrs) dir-file-attrs))
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			(error (kill-buffer (current-buffer))))))))
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	  (unless (cdr dirs)
	    (set (make-local-variable 'Info-dir-contents-directory)
		 (file-name-as-directory (car dirs))))
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	  (setq dirs (cdr dirs))))
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      (or buffers
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	  (error "Can't find the Info directory node"))
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      ;; Distinguish the dir file that comes with Emacs from all the
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      ;; others.  Yes, that is really what this is supposed to do.
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      ;; The definition of `Info-directory-list' puts it first on that
      ;; list and so last in `buffers' at this point.
      (setq buffer (car (last buffers))
	    others (delq buffer buffers))
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      ;; Insert the entire original dir file as a start; note that we've
      ;; already saved its default directory to use as the default
      ;; directory for the whole concatenation.
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      (insert-buffer buffer)
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      ;; Look at each of the other buffers one by one.
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      (dolist (other others)
	(let (this-buffer-nodes)
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	  ;; In each, find all the menus.
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	  (with-current-buffer other
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	    (goto-char (point-min))
	    ;; Find each menu, and add an elt to NODES for it.
	    (while (re-search-forward "^\\* Menu:" nil t)
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	      (while (and (zerop (forward-line 1)) (eolp)))
	      (let ((beg (point))
		    nodename end)
		(re-search-backward "^\^_")
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		(search-forward "Node: ")
		(setq nodename (Info-following-node-name))
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		(search-forward "\n\^_" nil 'move)
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		(beginning-of-line)
		(setq end (point))
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		(push (list nodename other beg end) this-buffer-nodes)))
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	    (if (assoc-ignore-case "top" this-buffer-nodes)
		(setq nodes (nconc this-buffer-nodes nodes))
	      (setq problems t)
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	      (message "No `top' node in %s" Info-dir-file-name)))))
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      ;; Add to the main menu a menu item for each other node.
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      (re-search-forward "^\\* Menu:")
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      (forward-line 1)
      (let ((menu-items '("top"))
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	    (end (save-excursion (search-forward "\^_" nil t) (point))))
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	(dolist (node nodes)
	  (let ((nodename (car node)))
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	    (save-excursion
	      (or (member (downcase nodename) menu-items)
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		  (re-search-forward (concat "^\\* +"
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					     (regexp-quote nodename)
					     "::")
				     end t)
		  (progn
		    (insert "* " nodename "::" "\n")
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		    (push nodename menu-items)))))))
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      ;; Now take each node of each of the other buffers
      ;; and merge it into the main buffer.
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      (dolist (node nodes)
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	(let ((case-fold-search t)
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	      (nodename (car node)))
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	  (goto-char (point-min))
	  ;; Find the like-named node in the main buffer.
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	  (if (re-search-forward (concat "^\^_.*\n.*Node: "
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					 (regexp-quote nodename)
					 "[,\n\t]")
				 nil t)
	      (progn
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		(search-forward "\n\^_" nil 'move)
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		(beginning-of-line)
		(insert "\n"))
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	    ;; If none exists, add one.
	    (goto-char (point-max))
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	    (insert "\^_\nFile: dir\tNode: " nodename "\n\n* Menu:\n\n"))
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	  ;; Merge the text from the other buffer's menu
	  ;; into the menu in the like-named node in the main buffer.
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	  (apply 'insert-buffer-substring (cdr node))))
      (Info-dir-remove-duplicates)
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      ;; Kill all the buffers we just made.
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      (mapc 'kill-buffer buffers)
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      (goto-char (point-min))
      (if problems
	  (message "Composing main Info directory...problems encountered, see `*Messages*'")
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	(message "Composing main Info directory...done"))
      (set (make-local-variable 'Info-dir-contents) (buffer-string))
      (set (make-local-variable 'Info-dir-file-attributes) dir-file-attrs)))
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  (setq default-directory Info-dir-contents-directory))
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(defvar Info-streamline-headings
  '(("Emacs" . "Emacs")
    ("Programming" . "Programming")
    ("Libraries" . "Libraries")
    ("World Wide Web\\|Net Utilities" . "Net Utilities"))
  "List of elements (RE . NAME) to merge headings matching RE to NAME.")

(defun Info-dir-remove-duplicates ()
  (let (limit)
    (goto-char (point-min))
    ;; Remove duplicate headings in the same menu.
    (while (search-forward "\n* Menu:" nil t)
      (setq limit (save-excursion (search-forward "\n" nil t)))
      ;; Look for the next heading to unify.
      (while (re-search-forward "^\\(\\w.*\\)\n\\*" limit t)
	(let ((name (match-string 1))
	      (start (match-beginning 0))
	      (entries nil) re)
	  ;; Check whether this heading should be streamlined.
	  (save-match-data
	    (dolist (x Info-streamline-headings)
	      (when (string-match (car x) name)
		(setq name (cdr x))
		(setq re (car x)))))
	  (if re (replace-match name t t nil 1))
	  (goto-char (if (re-search-forward "^[^* \n\t]" limit t)
			 (match-beginning 0)
		       (or limit (point-max))))
	  ;; Look for other headings of the same category and merge them.
	  (save-excursion
	    (while (re-search-forward "^\\(\\w.*\\)\n\\*" limit t)
	      (when (if re (save-match-data (string-match re (match-string 1)))
		      (equal name (match-string 1)))
		(forward-line 0)
		;; Delete redundant heading.
		(delete-region (match-beginning 0) (point))
		;; Push the entries onto `text'.
		(push
		 (delete-and-extract-region
		  (point)
		  (if (re-search-forward "^[^* \n\t]" nil t)
		      (match-beginning 0)
		    (or limit (point-max)))) entries))))
	  ;; Insert the entries just found.
	  (while (= (line-beginning-position 0) (1- (point)))
	    (backward-char))
	  (dolist (entry (nreverse entries))
	    (insert entry)
	    (while (= (line-beginning-position 0) (1- (point)))
	      (delete-region (1- (point)) (point))))
      
	  ;; Now remove duplicate entries under the same heading.
	  (let ((seen nil)
		(limit (point)))
	    (goto-char start)
	    (while (re-search-forward "^* \\([^:\n]+:\\(:\\|[^.\n]+\\).\\)"
				      limit 'move)
	      (let ((x (match-string 1)))
	  	(if (member-ignore-case x seen)
	  	    (delete-region (match-beginning 0)
	  			   (progn (re-search-forward "^[^ \t]" nil t)
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	  				  (match-beginning 0)))
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	  	  (push x seen))))))))))

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;; Note that on entry to this function the current-buffer must be the
;; *info* buffer; not the info tags buffer.
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(defun Info-read-subfile (nodepos)
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  ;; NODEPOS is either a position (in the Info file as a whole,
  ;; not relative to a subfile) or the name of a subfile.
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  (let (lastfilepos
	lastfilename)
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    (if (numberp nodepos)
	(save-excursion
	  (set-buffer (marker-buffer Info-tag-table-marker))
	  (goto-char (point-min))
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	  (or (looking-at "\^_")
	      (search-forward "\n\^_"))
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	  (forward-line 2)
	  (catch 'foo
	    (while (not (looking-at "\^_"))
	      (if (not (eolp))
		  (let ((beg (point))
			thisfilepos thisfilename)
		    (search-forward ": ")
		    (setq thisfilename  (buffer-substring beg (- (point) 2)))
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		    (setq thisfilepos (+ (point-min) (read (current-buffer))))
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		    ;; read in version 19 stops at the end of number.
		    ;; Advance to the next line.
		    (forward-line 1)
		    (if (> thisfilepos nodepos)
			(throw 'foo t))
		    (setq lastfilename thisfilename)
		    (setq lastfilepos thisfilepos))
		(forward-line 1)))))
      (setq lastfilename nodepos)
      (setq lastfilepos 0))
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    ;; Assume previous buffer is in Info-mode.
    ;; (set-buffer (get-buffer "*info*"))
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    (or (equal Info-current-subfile lastfilename)
	(let ((buffer-read-only nil))
	  (setq buffer-file-name nil)
	  (widen)
	  (erase-buffer)
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	  (info-insert-file-contents lastfilename)
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	  (set-buffer-modified-p nil)
	  (setq Info-current-subfile lastfilename)))
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    ;; Widen in case we are in the same subfile as before.
    (widen)
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    (goto-char (point-min))
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    (if (looking-at "\^_")
	(forward-char 1)
      (search-forward "\n\^_"))
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    (if (numberp nodepos)
	(+ (- nodepos lastfilepos) (point)))))
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(defvar Info-header-line nil
  "If the info node header is hidden, the text of the header.")
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(put 'Info-header-line 'risky-local-variable t)
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(defun Info-select-node ()
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"Select the info node that point is in.
Bind this in case the user sets it to nil."
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  (let ((case-fold-search t))
    (save-excursion
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      ;; Find beginning of node.
      (if (search-backward "\n\^_" nil 'move)
	  (forward-line 2)
	(if (looking-at "\^_")
	    (forward-line 1)
	  (signal 'search-failed (list "\n\^_"))))
      ;; Get nodename spelled as it is in the node.
      (re-search-forward "Node:[ \t]*")
      (setq Info-current-node
	    (buffer-substring-no-properties (point)
					    (progn
					      (skip-chars-forward "^,\t\n")
					      (point))))
      (Info-set-mode-line)
      ;; Find the end of it, and narrow.
      (beginning-of-line)
      (let (active-expression)
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	;; Narrow to the node contents
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	(narrow-to-region (point)
			  (if (re-search-forward "\n[\^_\f]" nil t)
			      (prog1
				  (1- (point))
				(if (looking-at "[\n\^_\f]*execute: ")
				    (progn
				      (goto-char (match-end 0))
				      (setq active-expression
					    (read (current-buffer))))))
			    (point-max)))
	(if Info-enable-active-nodes (eval active-expression))
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	(Info-fontify-node)
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	(setq Info-header-line (get-text-property (point-min) 'header-line))
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	(run-hooks 'Info-selection-hook)))))
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(defun Info-set-mode-line ()
  (setq mode-line-buffer-identification
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	(nconc (propertized-buffer-identification "%b")
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	       (list
		(concat " ("
			(file-name-nondirectory
			 (if (stringp Info-current-file)
			     Info-current-file
			   (or buffer-file-name "")))
			") "
			(or Info-current-node ""))))))
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;; Go to an info node specified with a filename-and-nodename string
;; of the sort that is found in pointers in nodes.

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(defun Info-goto-node (nodename &optional fork)
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  "Go to info node named NODENAME.  Give just NODENAME or (FILENAME)NODENAME.
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If NODENAME is of the form (FILENAME)NODENAME, the node is in the Info file
FILENAME; otherwise, NODENAME should be in the current Info file (or one of
its sub-files).
Completion is available, but only for node names in the current Info file.
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If FORK is non-nil (interactively with a prefix arg), show the node in
a new info buffer.
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If FORK is a string, it is the name to use for the new buffer."
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  (interactive (list (Info-read-node-name "Go to node: ") current-prefix-arg))
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  (info-initialize)
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  (if fork
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      (set-buffer
       (clone-buffer (concat "*info-" (if (stringp fork) fork nodename) "*") t)))
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