Small docstring update

[sxemacs] / lisp / info.el

;;; info.el --- info package for SXEmacs.
;; Keywords: help

;; Copyright (C) 1985, 1986, 1993, 1997 Free Software Foundation, Inc.
;; Copyright (C) 2005 Steve Youngs.

;; Author: Dave Gillespie <daveg@synaptics.com>
;;         Richard Stallman <rms@gnu.ai.mit.edu>
;; Maintainer: Dave Gillespie <daveg@synaptics.com>
;; Version: 1.07 of 7/22/93
;; Keywords: docs, help

;; This file is part of SXEmacs.

;; SXEmacs is free software: you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation, either version 3 of the License, or
;; (at your option) any later version.

;; SXEmacs 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 this program.  If not, see <http://www.gnu.org/licenses/>.

;;; Synched up with: Not synched with FSF.

;; Commentary:

;; This is based on an early Emacs 19 info.el file.
;;
;; Note that Info-directory has been replaced by Info-directory-list,
;; a search path of directories in which to find Info files.
;; Also, Info tries adding ".info" to a file name if the name itself
;; is not found.
;;
;; See the change log below for further details.


;; LCD Archive Entry:
;; info-dg|Dave Gillespie|daveg@synaptics.com
;; |Info reader with many enhancements; replaces standard info.el.
;; |93-07-22|1.07|~/modes/info.el

;; Also available from anonymous FTP on csvax.cs.caltech.edu.


;; Change Log:

;; Modified 3/7/1991 by Dave Gillespie:
;; (Author's address: daveg@synaptics.com or daveg@csvax.cs.caltech.edu)
;;
;; Added keys:  i, t, <, >, [, ], {, }, 6, 7, 8, 9, 0.
;; Look at help for info-mode (type ? in Info) for descriptions.
;;
;; If Info-directory-list is undefined and there is no INFOPATH
;; in the environment, use value of Info-directory for compatibility
;; with Emacs 18.57.
;;
;; All files named "localdir" found in the path are appended to "dir",
;; the Info directory.  For this to work, "dir" should contain only
;; one node (Top), and each "localdir" should contain no ^_ or ^L
;; characters.  Generally they will contain only one or several
;; additional lines for the top-level menu.  Note that "dir" is
;; modified in memory each time it is loaded, but not on disk.
;;
;; If "dir" contains a line of the form:  "* Locals:"
;; then the "localdir"s are inserted there instead of at the end.


;; Modified 4/3/1991 by Dave Gillespie:
;;
;; Added Info-mode-hook (suggested by Sebastian Kremer).
;; Also added epoch-info-startup/select-hooks from Simon Spero's info.el.
;;
;; Added automatic decoding of compressed Info files.
;; See documentation for the variable Info-suffix-list.  Default is to
;; run "uncompress" on ".Z" files and "unyabba" on ".Y" files.
;; (See comp.sources.unix v24i073-076 for yabba/unyabba, a free software
;; alternative to compress/uncompress.)
;; Note: "dir" and "localdir" files should not be compressed.
;;
;; Changed variables like Info-enable-edit to be settable by M-x set-variable.
;;
;; Added Info-auto-advance variable.  If t, SPC and DEL will act like
;; } and {, i.e., they advance to the next/previous node if at the end
;; of the buffer.
;;
;; Changed `u' to restore point to most recent location in that node.
;; Added `=' to do this manually at any time.  (Suggested by David Fox).
;;
;; Changed `m' and `0-9' to try interpreting menu name as a file name
;; if not found as a node name.  This allows (dir) menus of the form,
;;     Emacs::          Cool text editor
;; as a shorthand for
;;     Emacs:(emacs).   Cool text editor
;;
;; Enhanced `i' to use line-number information in the index.
;; Added `,' to move among all matches to a previous `i' command.
;;
;; Added `a' (Info-annotate) for adding personal notes to any Info node.
;; Notes are not stored in the actual Info files, but in the user's own
;; ~/.infonotes file.
;;
;; Added Info-footnote-tag, made default be "Ref" instead of "Note".
;;
;; Got mouse-click stuff to work under Emacs version 18.  Check it out!
;; Left and right clicks scroll the Info window.
;; Middle click goes to clicked-on node, e.g., "Next:", a menu, or a note.


;; Modified 6/29/1991 by Dave Gillespie:
;;
;; Renamed epoch-info-startup/select-hooks to Info-startup/select-hook.
;;
;; Made Info-select-node into a command on the `!' key.
;;
;; Added Info-mouse-support user option.
;;
;; Cleaned up the implementation of some routines.
;;
;; Added special treatment of quoted words in annotations:  The `g'
;; command for a nonexistent node name scans for an annotation
;; (in any node of any file) containing that name in quotes:  g foo RET
;; looks for an annotation containing:  "foo"  or:  <<foo>>
;; If found, it goes to that file and node.
;;
;; Added a call to set up Info-directory-list in Info-find-node to
;; work around a bug in GNUS where it calls Info-goto-node before info.
;;
;; Added completion for `g' command (inspired by Richard Kim's infox.el).
;; Completion knows all node names for the current file, and all annotation
;; tags (see above).  It does not complete file names or node names in
;; other files.
;;
;; Added `k' (Info-emacs-key) and `*' (Info-elisp-ref) commands.  You may
;; wish to bind these to global keys outside of Info mode.
;;
;; Allowed localdir files to be full dir-like files; only the menu part
;; of each localdir is copied.  Also, redundant menu items are omitted.
;;
;; Changed Info-history to hold only one entry at a time for each node,
;; and to be circular so that multiple `l's come back again to the most
;; recent node.  Note that the format of Info-history entries has changed,
;; which may interfere with external programs that try to operate on it.
;; (Also inspired by Kim's infox.el).
;;
;; Changed `n', `]', `l', etc. to accept prefix arguments to move several
;; steps at once.  Most accept negative arguments to move oppositely.
;;
;; Changed `?' to bury *Help* buffer afterwards to keep it out of the way.
;;
;; Rearranged `?' key's display to be a little better for new users.
;;
;; Changed `a' to save whole window configuration and restore on C-c C-c.
;;
;; Fixed the bug reported by Bill Reynolds on gnu.emacs.bugs.
;;
;; Changed Info-last to restore window-start as well as cursor position.
;;
;; Changed middle mouse button in space after end of node to do Info-last
;; if we got here by following a cross reference, else do Info-global-next.
;;
;; Added some new mouse bindings: shift-left = Info-global-next,
;; shift-right = Info-global-prev, shift-middle = Info-last.
;;
;; Fixed Info-follow-reference not to make assumptions about length
;; of Info-footnote-tag [Linus Tolke].
;;
;; Changed default for Info-auto-advance mode to be press-twice-for-next-node.
;;
;; Modified x-mouse-ignore to preserve last-command variable, so that
;; press-twice Info-auto-advance mode works with the mouse.


;; Modified 3/4/1992 by Dave Gillespie:
;;
;; Added an "autoload" command to help autoload.el.
;;
;; Changed `*' command to look for file `elisp' as well as for `lispref'.
;;
;; Fixed a bug involving footnote names containing regexp special characters.
;;
;; Fixed a bug in completion during `f' (or `r') command.
;;
;; Added TAB (Info-next-reference), M-TAB, and RET keys to Info mode.
;;
;; Added new bindings, `C-h C-k' for Info-emacs-key and `C-h C-f' for
;; Info-elisp-ref.  These bindings are made when info.el is loaded, and
;; only if those key sequences were previously unbound.  These bindings
;; work at any time, not just when Info is already running.


;; Modified 3/8/1992 by Dave Gillespie:
;;
;; Fixed some long lines that were causing trouble with mailers.


;; Modified 3/9/1992 by Dave Gillespie:
;;
;; Added `C-h C-i' (Info-query).
;;
;; Added Info-novice mode, warns if the user attempts to switch to
;; a different Info file.
;;
;; Fixed a bug that caused problems using compressed Info files
;; and Info-directory-list at the same time.
;;
;; Disabled Info-mouse-support by default if Epoch or Hyperbole is in use.
;;
;; Added an expand-file-name call to Info-find-node to fix a small bug.


;; Modified 5/22/1992 by Dave Gillespie:
;;
;; Added "standalone" operation:  "emacs -f info" runs Emacs specifically
;; for use as an Info browser.  In this mode, the `q' key quits Emacs
;; itself.  Also, "emacs -f info arg" starts in Info file "arg" instead
;; of "dir".
;;
;; Changed to prefer "foo.info" over "foo".  If both exist, "foo" is
;; probably a directory or executable program!
;;
;; Made control-mouse act like regular-mouse does in other buffers.
;; (In most systems, this will be set-cursor for left-mouse, x-cut
;; for right-mouse, and x-paste, which will be an error, for
;; middle-mouse.)
;;
;; Improved prompting and searching for `,' key.
;;
;; Fixed a bug where some "* Menu:" lines disappeared when "dir"
;; contained several nodes.


;; Modified 9/10/1992 by Dave Gillespie:
;;
;; Mixed in support for XEmacs.  Mouse works the same as in
;; the other Emacs versions by default; added Info-lucid-mouse-style
;; variable, which enables mouse operation similar to XEmacs's default.
;;
;; Fixed a bug where RET couldn't understand "* Foo::" if "Foo" was a
;; file name instead of a node name.
;;
;; Added `x' (Info-bookmark), a simple interface to the annotation
;; tags feature.  Added `j' (Info-goto-bookmark), like `g' but only
;; completes bookmarks.
;;
;; Added `<<tag>>' as alternate to `"tag"' in annotations.
;;
;; Added `v' (Info-visit-file), like Info-goto-node but specialized
;; for going to a new Info file (with file name completion).
;;
;; Added recognition of gzip'd ".z" files.


;; Modified 5/9/1993 by Dave Gillespie:
;;
;; Merged in various things from FSF's latest Emacs 19 info.el.

;; Modified 6/2/1993 by Dave Gillespie:
;;
;; Changed to use new suffix ".gz" for gzip files.


;; Modified 7/22/1993 by Dave Gillespie:
;;
;; Changed Info-footnote-tag to "See" instead of "Ref".
;;
;; Extended Info-fontify-node to work with FSF version of Emacs 19.

;; Modified 7/30/1993 by Jamie Zawinski:
;;
;; Commented out the tty and fsf19 mouse support, because why bother.
;; Commented out the politically incorrect version of XEmacs mouse support.
;; Commented out mouse scrolling bindings because the party line on that
;;  is "scrollbars are coming soon."
;; Commented out munging of help-for-help's doc; put it in help.el.
;; Did Info-edit-map the modern XEmacs way.
;; Pruned extra cruft from fontification and mouse handling code.
;; Fixed ASCII-centric bogosity in unreading of events.

;; Modified 8/11/95 by Chuck Thompson:
;;
;; Removed any pretense of ever referencing Info-directory since it
;; wasn't working anyhow.

;; Modified 4/5/97 by Tomasz J. Cholewo:
;;
;; Modified Info-search to use with-caps-disable-folding

;; Modified 6/21/97 by Hrvoje Niksic
;;
;; Fixed up Info-next-reference to work sanely when n < 0.
;; Added S-tab binding.

;; Modified 1997-07-10 by Karl M. Hegbloom
;;
;; Added `Info-minibuffer-history'
;; (also added to defaults in "lisp/utils/savehist.el")
;;  Other changes in main ChangeLog.

;; Modified 1998-03-29 by Oscar Figueiredo
;;
;; Added automatic dir/localdir (re)building capability for directories that
;; contain none or when it has become older than info files in the same
;; directory.

;; Modified 1998-09-23 by Didier Verna <didier@xemacs.org>
;;
;; Use the new macro `with-search-caps-disable-folding'

;; Code:
(eval-when-compile
  (condition-case nil (require 'browse-url) (error nil)))

(defgroup info nil
  "The info package for Emacs."
  :group 'help
  :group 'docs)

(defgroup info-faces nil
  "The faces used by info browser."
  :group 'info
  :group 'faces)


(defcustom Info-inhibit-toolbar nil
  "*Non-nil means don't use the specialized Info toolbar."
  :type 'boolean
  :group 'info)

(defcustom Info-novice nil
  "*Non-nil means to ask for confirmation before switching Info files."
  :type 'boolean
  :group 'info)

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

(defvar Info-keeping-history t
  "Non-nil if Info-find-node should modify Info-history.
This is for use only by certain internal Info routines.")

(defvar Info-minibuffer-history nil
  "Minibuffer history for Info.")

(defcustom Info-enable-edit nil
  "*Non-nil means the \\<Info-mode-map>\\[Info-edit] command in Info
can edit the current node.
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,
because that gives you a printed manual as well."
  :type 'boolean
  :group 'info)

(defcustom Info-enable-active-nodes t
  "*Non-nil allows Info to execute Lisp code associated with nodes.
The Lisp code is executed when the node is selected."
  :type 'boolean
  :group 'info)

(defcustom Info-restoring-point t
  "*Non-nil means to restore the cursor position when re-entering a node."
  :type 'boolean
  :group 'info)

(defcustom Info-auto-advance 'twice
  "*Control what SPC and DEL do when they can't scroll any further.
If nil, they beep and remain in the current node.
If t, they move to the next node (like Info-global-next/prev).
If anything else, they must be pressed twice to move to the next node."
  :type '(choice (const :tag "off" nil)
                 (const :tag "advance" t)
                 (const :tag "confirm" twice))
  :group 'info)

(defcustom Info-fontify t
  "*Non-nil enables font features in XEmacs.
This variable is ignored unless running under XEmacs."
  :type 'boolean
  :group 'info)

(defcustom Info-additional-search-directory-list nil
  "*List of additional directories to search for Info documentation
files.  These directories are not searched for merging the `dir'
file. An example might be something like:
\"/usr/local/lib/xemacs/packages/lisp/calc/\""
  :type '(repeat directory)
  :group 'info)

(defcustom Info-auto-generate-directory 'if-outdated
  "*When to auto generate an info directory listing.
Possible values are:
nil or `never' never auto-generate a directory listing,
  use any existing `dir' or `localdir' file and ignore info
  directories containing none
`always' auto-generate a directory listing ignoring existing
  `dir' and `localdir' files
`if-missing', the default, auto-generates a directory listing
  if no `dir' or `localdir' file is present.  Otherwise the
  contents of any of these files is used instead.
`if-outdated' auto-generates a directory listing if the `dir'
  and `localdir' are either inexistent or outdated (touched
  less recently than an info file in the same directory)."
  :type '(choice (const :tag "never" never)
                 (const :tag "always" always)
                 (const :tag "if-missing" if-missing)
                 (const :tag "if-outdated" if-outdated))
  :group 'info)

(defcustom Info-save-auto-generated-dir 'never
  "*Whether an auto-generated info directory listing should be saved.
Possible values are:
nil or `never', the default, auto-generated info directory
  information will never be saved.
`always', auto-generated info directory information will be saved to
  a `dir' file in the same directory overwriting it if it exists
`conservative', auto-generated info directory information will be saved
  to a `dir' file in the same directory but the user is asked before
  overwriting any existing file."
  :type '(choice (const :tag "never" never)
                 (const :tag "always" always)
                 (const :tag "conservative" conservative))
  :group 'info)

(defconst Info-emacs-info-file-name "sxemacs.info"
  "The filename of the SXEmacs info for `Info-goto-emacs-command-node'
\(`\\<help-mode-map>\\[Info-goto-emacs-command-node]'\)")

;;;###autoload
(defvar Info-directory-list nil
  "List of directories to search for Info documentation files.