;;; helper.el --- utility help package supporting help in electric modes -*- lexical-binding: t; -*- ;; Copyright (C) 1985-2023 Free Software Foundation, Inc. ;; Author: K. Shane Hartman ;; Maintainer: emacs-devel@gnu.org ;; Keywords: help ;; 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 . ;;; Commentary: ;;; Code: ;; hey, here's a helping hand. ;; Bind this to a string for in "... Other keys ". ;; 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-keymap Helper-help-map "m" #'Helper-describe-mode "b" #'Helper-describe-bindings "c" #'Helper-describe-key-briefly "k" #'Helper-describe-key ;;"f" #'Helper-describe-function ;;"v" #'Helper-describe-variable "?" #'Helper-help-options (key-description (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)) (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 (mapcar #'substitute-command-keys '("\\`SPC' forward, \\`DEL' back. Other keys %s" "\\`SPC' scrolls forward. Other keys %s" "\\`DEL' scrolls back. Other keys %s" "Type anything to %s"))) blurb) (setq continue (read-event)) (cond ((and (memq continue '(?\s ?\C-v)) (< state 2)) (scroll-up)) ((eq continue ?\C-l) (recenter)) ((and (or (eq continue 'backspace) (eq continue ?\177)) (zerop (% state 2))) (scroll-down)) (t (setq continue nil)))))))) (defun Helper-help-options () "Describe help options." (interactive) (message (substitute-command-keys "\\`c' (key briefly), \\`m' (mode), \\`k' (key), \\`b' (bindings)")) (sit-for 4)) (defun Helper-describe-key-briefly (key) "Briefly describe binding of KEY." (interactive "kDescribe key briefly: ") (describe-key-briefly key) (sit-for 4)) (defun Helper-describe-key (key) "Describe binding of KEY." (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 (format-mode-line mode-name)) (documentation (documentation major-mode))) (with-current-buffer (get-buffer-create "*Help*") (setq buffer-read-only nil) (erase-buffer) (insert name " Mode\n" documentation) (help-mode))) (Helper-help-scroller)) ;;;###autoload (defun Helper-describe-bindings () "Describe local key bindings of current mode." (interactive) (save-window-excursion (describe-bindings)) (Helper-help-scroller)) ;;;###autoload (defun Helper-help () "Provide help for current mode." (interactive) (let ((continue t) c) (while continue (message (substitute-command-keys "Help (Type \\`?' for further options)")) (setq c (read-key-sequence nil)) (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)))))) (provide 'helper) ;;; helper.el ends here