;;; help-macro.el --- makes command line help such as help-for-help -*- lexical-binding: t -*-
;; Copyright (C) 1993-1994, 2001-2024 Free Software Foundation, Inc.
;; Author: Lynn Slater <lrs@indetech.com>
;; Maintainer: emacs-devel@gnu.org
;; Created: Mon Oct 1 11:42:39 1990
;; Adapted-By: ESR
;; Package: emacs
;; 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 3 of the License, 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. If not, see <https://www.gnu.org/licenses/>.
;;; Commentary:
;; This file supplies the macro `make-help-screen' which constructs
;; 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 example, the (long-since defunct) GNU Emacs
;; Empire Tool used this for every "nested" mode map called from the
;; main mode map.
;; The name of this package was changed from help-screen.el to
;; help-macro.el in order to fit in a 14-character limit.
;;-> *********************** 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
;;-> based in part on empire-sector-civ-threshold
;;->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)
;;; Code:
(require 'backquote)
;; This needs to be autoloaded because it is used in the
;; make-help-screen macro. Using (bound-and-true-p three-step-help)
;; is not an acceptable alternative, because nothing loads help-macro
;; in a normal session, so any user customization would never be applied.
;;;###autoload
(defcustom three-step-help nil
"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 \\[help-command] \\[help-command]
gives the window that lists the options."
:type 'boolean
:group 'help)
(defmacro make-help-screen (fname help-line help-text helped-map
&optional buffer-name)
"Construct help-menu function name FNAME.
When invoked, FNAME shows HELP-LINE and reads a command using HELPED-MAP.
If the command is the help character, FNAME displays HELP-TEXT
and continues trying to read a command using HELPED-MAP.
If HELP-TEXT contains the sequence `%THIS-KEY%', that is replaced
with the key sequence that invoked FNAME.
When FNAME finally does get a command, it executes that command
and then returns."
(declare (indent defun))
`(defun ,fname ()
"Help command."
(interactive)
(help--help-screen ,help-line ,help-text ,helped-map ,buffer-name)))
;;;###autoload
(defun help--help-screen (help-line help-text helped-map buffer-name)
(let ((line-prompt
(substitute-command-keys help-line))
(help-buffer-under-preparation t))
(when three-step-help
(message "%s" line-prompt))
(let* ((help-screen help-text)
;; 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))
(new-minor-mode-map-alist minor-mode-map-alist)
(prev-frame (selected-frame))
config new-frame key char)
(when (string-match "%THIS-KEY%" help-screen)
(setq help-screen
(replace-match (help--key-description-fontified
(substring (this-command-keys) 0 -1))
t t help-screen)))
(unwind-protect
(let ((minor-mode-map-alist nil))
(setcdr local-map helped-map)
(define-key local-map [t] #'undefined)
;; Make the scroll bar keep working normally.
(define-key local-map [vertical-scroll-bar]
(lookup-key global-map [vertical-scroll-bar]))
(if three-step-help
(progn
(setq key (let ((overriding-local-map local-map))
(read-key-sequence nil)))
;; 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)))
(setq char ??))
(when (or (eq char ??) (eq char help-char)
(memq char help-event-list))
(setq config (current-window-configuration))
(pop-to-buffer (or buffer-name " *Metahelp*") nil t)
(and (fboundp 'make-frame)
(not (eq (window-frame)
prev-frame))
(setq new-frame (window-frame)
config nil))
(setq buffer-read-only nil)
(let ((inhibit-read-only t))
(erase-buffer)
(insert (substitute-command-keys help-screen)))
(let ((minor-mode-map-alist new-minor-mode-map-alist))
(help-mode)
(variable-pitch-mode)
(setq new-minor-mode-map-alist minor-mode-map-alist))
(goto-char (point-min))
(while (or (memq char (append help-event-list
(cons help-char '( ?? ?\C-v ?\s ?\177 ?\M-v ?\S-\s
deletechar backspace vertical-scroll-bar
home end next prior up down))))
(eq (car-safe char) 'switch-frame)
(equal key "\M-v"))
(condition-case nil
(cond
((eq (car-safe char) 'switch-frame)
(handle-switch-frame char))
((memq char '(?\C-v ?\s next end))
(scroll-up))
((or (memq char '(?\177 ?\M-v ?\S-\s deletechar backspace prior home))
(equal key "\M-v"))
(scroll-down))
((memq char '(down))
(scroll-up 1))
((memq char '(up))
(scroll-down 1)))
(error nil))
(let ((cursor-in-echo-area t)
(overriding-local-map local-map))
(frame-toggle-on-screen-keyboard (selected-frame) nil)
(setq key (read-key-sequence
(format "Type one of listed options%s: "
(if (pos-visible-in-window-p
(point-max))
""
(concat ", or "
(help--key-description-fontified (kbd "<PageDown>"))
"/"
(help--key-description-fontified (kbd "<PageUp>"))
"/"
(help--key-description-fontified (kbd "SPC"))
"/"
(help--key-description-fontified (kbd "DEL"))
" to scroll")))
nil nil nil nil
;; Disable ``text conversion''. OS
;; input methods might otherwise chose
;; to insert user input directly into
;; a buffer.
t)
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))))
;; We don't need the prompt any more.
(message "")
;; 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)
(let ((defn (lookup-key local-map key)))
(if defn
(progn
(when config
(set-window-configuration config)
(setq config nil))
;; Temporarily rebind `minor-mode-map-alist'
;; to `new-minor-mode-map-alist' (Bug#10454).
(let ((minor-mode-map-alist new-minor-mode-map-alist))
;; `defn' must make sure that its frame is
;; selected, so we won't iconify it below.
(call-interactively defn))
(when new-frame
;; Do not iconify the selected frame.
(unless (eq new-frame (selected-frame))
(iconify-frame new-frame))
(setq new-frame nil)))
(unless (equal (key-description key) "C-g")
(message (substitute-command-keys
(format "No help command is bound to `\\`%s''"
(key-description key))))
(ding))))))
(when config
(set-window-configuration config))
(when new-frame
(iconify-frame new-frame))
(setq minor-mode-map-alist new-minor-mode-map-alist)))))
(provide 'help-macro)
;;; help-macro.el ends here