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;;; help-macro.el --- makes command line help such as help-for-help
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;; Copyright (C) 1993, 1994, 2001, 2002, 2003, 2004,
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;;   2005, 2006 Free Software Foundation, Inc.
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;; Author: Lynn Slater <lrs@indetech.com>
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;; Maintainer: FSF
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;; Created: Mon Oct  1 11:42:39 1990
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;; Adapted-By: ESR

;; 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 2, 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
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;; along with GNU Emacs; see the file COPYING.  If not, write to the
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;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
;; Boston, MA 02110-1301, USA.
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;;; Commentary:
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;; This file supplies the macro make-help-screen which constructs
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;; single character dispatching with browsable help such as that provided
;; by help-for-help. This can be used to make many modes easier to use; for
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;; example, the GNU Emacs Empire Tool uses this for every "nested" mode map
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;; called from the main mode map.

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;;       The name of this package was changed from help-screen.el to
;; help-macro.el in order to fit in a 14-character limit.

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;;-> ***********************  Example of use *********************************

;;->(make-help-screen help-for-empire-redistribute-map
;;->		  "c:civ m:mil p:population f:food ?"
;;->		  "You have discovered the GEET redistribution commands
;;->   From here, you can use the following options:
;;->
;;->c	Redistribute civs from overfull sectors into connected underfull ones
;;->	  The functions typically named by empire-ideal-civ-fcn control
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;;->          based in part on empire-sector-civ-threshold
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;;->m	Redistribute military using levels given by empire-ideal-mil-fcn
;;->p	Redistribute excess population to highways for max pop growth
;;->	  Excess is any sector so full babies will not be born.
;;->f	Even out food on highways to highway min and leave levels
;;->	  This is good to pump max food to all warehouses/dist pts
;;->
;;->
;;->Use \\[help-for-empire-redistribute-map] for help on redistribution.
;;->Use \\[help-for-empire-extract-map] for help on data extraction.
;;->Please use \\[describe-key] to find out more about any of the other keys."
;;->		  empire-shell-redistribute-map)

;;->  (define-key c-mp "\C-h" 'help-for-empire-redistribute-map)
;;->  (define-key c-mp help-character 'help-for-empire-redistribute-map)

;;; Change Log:
;;
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;; 22-Jan-1991		Lynn Slater x2048
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;;    Last Modified: Mon Oct  1 11:43:52 1990 #3 (Lynn Slater)
;;    documented better

;;; Code:

(require 'backquote)

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;;;###autoload
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(defcustom three-step-help nil
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  "*Non-nil means give more info about Help command in three steps.
The three steps are simple prompt, prompt with all options,
and window listing and describing the options.
A value of nil means skip the middle step, so that
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\\[help-command] \\[help-command] gives the window that lists the options."
  :type 'boolean
  :group 'help)
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(defmacro make-help-screen (fname help-line help-text helped-map)
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  "Construct help-menu function name FNAME.
When invoked, FNAME shows HELP-LINE and reads a command using HELPED-MAP.
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If the command is the help character, FNAME displays HELP-TEXT
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and continues trying to read a command using HELPED-MAP.
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If HELP-TEXT contains the sequence `%THIS-KEY%', that is replaced
with the key sequence that invoked FNAME.
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When FNAME finally does get a command, it executes that command
and then returns."
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 (let ((doc-fn (intern (concat (symbol-name fname) "-doc"))))
  `(progn
    (defun ,doc-fn () ,help-text)
    (defun ,fname ()
	   "Help command."
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	   (interactive)
	   (let ((line-prompt
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		  (substitute-command-keys ,help-line)))
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	     (if three-step-help
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		 (message "%s" line-prompt))
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	     (let* ((help-screen (documentation (quote ,doc-fn)))
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		    ;; We bind overriding-local-map for very small
		    ;; sections, *excluding* where we switch buffers
		    ;; and where we execute the chosen help command.
		    (local-map (make-sparse-keymap))
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		    (minor-mode-map-alist nil)
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		    (prev-frame (selected-frame))
		    config new-frame key char)
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	       (if (string-match "%THIS-KEY%" help-screen)
		   (setq help-screen
			 (replace-match (key-description (substring (this-command-keys) 0 -1))
					t t help-screen)))
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	       (unwind-protect
		   (progn
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		     (setcdr local-map ,helped-map)
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		     (define-key local-map [t] 'undefined)
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		     ;; Make the scroll bar keep working normally.
		     (define-key local-map [vertical-scroll-bar]
		       (lookup-key global-map [vertical-scroll-bar]))
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		     (if three-step-help
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			 (progn
			   (setq key (let ((overriding-local-map local-map))
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				       (read-key-sequence nil)))
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			   ;; Make the HELP key translate to C-h.
			   (if (lookup-key function-key-map key)
			       (setq key (lookup-key function-key-map key)))
			   (setq char (aref key 0)))
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		       (setq char ??))
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		     (if (or (eq char ??) (eq char help-char)
			     (memq char help-event-list))
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			 (progn
			   (setq config (current-window-configuration))
			   (switch-to-buffer-other-window "*Help*")
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			   (and (fboundp 'make-frame)
				(not (eq (window-frame (selected-window))
					 prev-frame))
				(setq new-frame (window-frame (selected-window))
				      config nil))
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			   (setq buffer-read-only nil)
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			   (let ((inhibit-read-only t))
			     (erase-buffer)
			     (insert help-screen))
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			   (help-mode)
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			   (goto-char (point-min))
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			   (while (or (memq char (append help-event-list
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							 (cons help-char '(?? ?\C-v ?\s ?\177 delete backspace vertical-scroll-bar ?\M-v))))
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				      (eq (car-safe char) 'switch-frame)
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				      (equal key "\M-v"))
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			     (condition-case nil
				 (progn
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				   (if (eq (car-safe char) 'switch-frame)
				       (handle-switch-frame char))
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				   (if (memq char '(?\C-v ?\s))
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				       (scroll-up))
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				   (if (or (memq char '(?\177 ?\M-v
							delete backspace))
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					   (equal key "\M-v"))
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				       (scroll-down)))
			       (error nil))
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			     (let ((cursor-in-echo-area t)
				   (overriding-local-map local-map))
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			       (setq key (read-key-sequence
					  (format "Type one of the options listed%s: "
						  (if (pos-visible-in-window-p
						       (point-max))
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						      "" ", or SPACE or DEL to scroll")))
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				     char (aref key 0)))

			     ;; If this is a scroll bar command, just run it.
			     (when (eq char 'vertical-scroll-bar)
			       (command-execute (lookup-key local-map key) nil key)))))
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		     ;; We don't need the prompt any more.
		     (message "")
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		     ;; Mouse clicks are not part of the help feature,
		     ;; so reexecute them in the standard environment.
		     (if (listp char)
			 (setq unread-command-events
			       (cons char unread-command-events)
			       config nil)
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		       (let ((defn (lookup-key local-map key)))
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			 (if defn
			     (progn
			       (if config
				   (progn
				     (set-window-configuration config)
				     (setq config nil)))
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			       (if new-frame
				   (progn (iconify-frame new-frame)
					  (setq new-frame nil)))
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			       (call-interactively defn))
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			   (ding)))))
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		 (if new-frame (iconify-frame new-frame))
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		 (if config
		     (set-window-configuration config))))))
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     )))
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(provide 'help-macro)
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;;; arch-tag: 59fee949-1686-485a-8a05-83418073e257
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;;; help-macro.el ends here