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+;; helper - utility help package for modes which want to provide help
+;; without relinquishing control, e.g. `electric' modes.
+
+;; Copyright (C) 1985 Free Software Foundation, Inc.
+;; Principal author K. Shane Hartman
+
+;; This file is part of GNU Emacs.
+
+;; GNU Emacs is free software; you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation; either version 1, or (at your option)
+;; any later version.
+
+;; GNU Emacs is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+
+;; You should have received a copy of the GNU General Public License
+;; along with GNU Emacs; see the file COPYING.  If not, write to
+;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
+
+
+(provide 'helper)			; hey, here's a helping hand.
+
+;; Bind this to a string for <blank> in "... Other keys <blank>".
+;; Helper-help uses this to construct help string when scrolling.
+;; Defaults to "return"
+(defvar Helper-return-blurb nil)
+
+;; Keymap implementation doesn't work too well for non-standard loops.
+;; But define it anyway for those who can use it.  Non-standard loops
+;; will probably have to use Helper-help.  You can't autoload the
+;; keymap either.
+
+
+(defvar Helper-help-map nil)
+(if Helper-help-map
+    nil
+  (setq Helper-help-map (make-keymap))
+  ;(fillarray Helper-help-map 'undefined)
+  (define-key Helper-help-map "m" 'Helper-describe-mode)
+  (define-key Helper-help-map "b" 'Helper-describe-bindings)
+  (define-key Helper-help-map "c" 'Helper-describe-key-briefly)
+  (define-key Helper-help-map "k" 'Helper-describe-key)
+  ;(define-key Helper-help-map "f" 'Helper-describe-function)
+  ;(define-key Helper-help-map "v" 'Helper-describe-variable)
+  (define-key Helper-help-map "?" 'Helper-help-options)
+  (define-key Helper-help-map (char-to-string help-char) 'Helper-help-options)
+  (fset 'Helper-help-map Helper-help-map))
+
+(defun Helper-help-scroller ()
+  (let ((blurb (or (and (boundp 'Helper-return-blurb)
+			Helper-return-blurb)
+		   "return")))
+    (save-window-excursion
+      (goto-char (window-start (selected-window)))
+      (if (get-buffer-window "*Help*")
+	  (pop-to-buffer "*Help*")
+	(switch-to-buffer "*Help*"))
+      (goto-char (point-min))
+      (let ((continue t) state)
+	(while continue
+	  (setq state (+ (* 2 (if (pos-visible-in-window-p (point-max)) 1 0))
+			 (if (pos-visible-in-window-p (point-min)) 1 0)))
+	  (message
+	    (nth state
+		 '("Space forward, Delete back. Other keys %s"
+		   "Space scrolls forward. Other keys %s"
+		   "Delete scrolls back. Other keys %s"
+		   "Type anything to %s"))
+	    blurb)
+	  (setq continue (read-char))
+	  (cond ((and (memq continue '(?\ ?\C-v)) (< state 2))
+		 (scroll-up))
+		((= continue ?\C-l)
+		 (recenter))
+		((and (= continue ?\177) (zerop (% state 2)))
+		 (scroll-down))
+		(t (setq continue nil))))))))
+
+(defun Helper-help-options ()
+  "Describe help options."
+  (interactive)
+  (message "c (key briefly), m (mode), k (key), b (bindings)")
+  ;(message "c (key briefly), m (mode), k (key), v (variable), f (function)")
+  (sit-for 4))
+
+(defun Helper-describe-key-briefly (key)
+  "Briefly describe binding of KEYS."
+  (interactive "kDescribe key briefly: ")
+  (describe-key-briefly key)
+  (sit-for 4))
+
+(defun Helper-describe-key (key)
+  "Describe binding of KEYS."
+  (interactive "kDescribe key: ")
+  (save-window-excursion (describe-key key))
+  (Helper-help-scroller))
+
+(defun Helper-describe-function ()
+  "Describe a function.  Name read interactively."
+  (interactive)
+  (save-window-excursion (call-interactively 'describe-function))
+  (Helper-help-scroller))
+
+(defun Helper-describe-variable ()
+  "Describe a variable.  Name read interactively."
+  (interactive)
+  (save-window-excursion (call-interactively 'describe-variable))
+  (Helper-help-scroller))
+
+(defun Helper-describe-mode ()
+  "Describe the current mode."
+  (interactive)
+  (let ((name mode-name)
+	(documentation (documentation major-mode)))
+    (save-excursion
+      (set-buffer (get-buffer-create "*Help*"))
+      (erase-buffer)
+      (insert name " Mode\n" documentation)))
+  (Helper-help-scroller))
+
+(defun Helper-describe-bindings ()
+  "Describe local key bindings of current mode."
+  (interactive)
+  (message "Making binding list...")
+  (save-window-excursion (describe-bindings))
+  (Helper-help-scroller))
+
+(defun Helper-help ()
+  "Provide help for current mode."
+  (interactive)
+  (let ((continue t) c)
+    (while continue
+      (message "Help (Type ? for further options)")
+      (setq c (char-to-string (downcase (read-char))))
+      (setq c (lookup-key Helper-help-map c))
+      (cond ((eq c 'Helper-help-options)
+	     (Helper-help-options))
+	    ((commandp c)
+	     (call-interactively c)
+	     (setq continue nil))
+	    (t
+	     (ding)
+	     (setq continue nil))))))
+