;;; ehelp.el --- bindings for electric-help mode ;; Copyright (C) 1986 Free Software Foundation, Inc. ;; Maintainer: FSF ;; Keywords: help, extensions ;; 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 ;; along with GNU Emacs; see the file COPYING. If not, write to ;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. ;;; Commentary: ;; This package provides a pre-packaged `Electric Help Mode' for ;; browsing on-line help screens. There is one entry point, ;; `with-electric-help'; All you have to give it is a no-argument ;; function that generates the actual text of the help into the current ;; buffer. ;;; Code: (require 'electric) (defvar electric-help-map () "Keymap defining commands available in `electric-help-mode'.") (put 'electric-help-undefined 'suppress-keymap t) (if electric-help-map () (let ((map (make-keymap))) (fillarray (car (cdr map)) 'electric-help-undefined) (define-key map (char-to-string meta-prefix-char) (copy-keymap map)) (define-key map (char-to-string help-char) 'electric-help-help) (define-key map "?" 'electric-help-help) (define-key map " " 'scroll-up) (define-key map "\^?" 'scroll-down) (define-key map "." 'beginning-of-buffer) (define-key map "<" 'beginning-of-buffer) (define-key map ">" 'end-of-buffer) ;(define-key map "\C-g" 'electric-help-exit) (define-key map "q" 'electric-help-exit) (define-key map "Q" 'electric-help-exit) ;;a better key than this? (define-key map "r" 'electric-help-retain) (setq electric-help-map map))) (defun electric-help-mode () "`with-electric-help' temporarily places its buffer in this mode. \(On exit from `with-electric-help', the buffer is put in `default-major-mode'.)" (setq buffer-read-only t) (setq mode-name "Help") (setq major-mode 'help) (setq mode-line-buffer-identification '(" Help: %b")) (use-local-map electric-help-map) ;; this is done below in with-electric-help ;(run-hooks 'electric-help-mode-hook) ) (defun with-electric-help (thunk &optional buffer noerase) "Arguments are THUNK &optional BUFFER NOERASE. BUFFER defaults to \"*Help*\" THUNK is a function of no arguments which is called to initialize the contents of BUFFER. BUFFER will be erased before THUNK is called unless NOERASE is non-nil. THUNK will be called with `standard-output' bound to the buffer specified by BUFFER After THUNK has been called, this function \"electrically\" pops up a window in which BUFFER is displayed and allows the user to scroll through that buffer in electric-help-mode. When the user exits (with `electric-help-exit', or otherwise) the help buffer's window disappears (i.e., we use `save-window-excursion') BUFFER is put into `default-major-mode' (or `fundamental-mode') when we exit" (setq buffer (get-buffer-create (or buffer "*Help*"))) (let ((one (one-window-p t)) (config (current-window-configuration)) (bury nil)) (unwind-protect (save-excursion (if one (goto-char (window-start (selected-window)))) (let ((pop-up-windows t)) (pop-to-buffer buffer)) (save-excursion (set-buffer buffer) (electric-help-mode) (setq buffer-read-only nil) (or noerase (erase-buffer))) (let ((standard-output buffer)) (if (not (funcall thunk)) (progn (set-buffer buffer) (set-buffer-modified-p nil) (goto-char (point-min)) (if one (shrink-window-if-larger-than-buffer (selected-window)))))) (set-buffer buffer) (run-hooks 'electric-help-mode-hook) (if (eq (car-safe (electric-help-command-loop)) 'retain) (setq config (current-window-configuration)) (setq bury t))) (message "") (set-buffer buffer) (setq buffer-read-only nil) (condition-case () (funcall (or default-major-mode 'fundamental-mode)) (error nil)) (set-window-configuration config) (if bury (progn ;;>> Perhaps this shouldn't be done. ;; so that when we say "Press space to bury" we mean it (replace-buffer-in-windows buffer) ;; must do this outside of save-window-excursion (bury-buffer buffer)))))) (defun electric-help-command-loop () (catch 'exit (if (pos-visible-in-window-p (point-max)) (progn (message "<<< Press Space to bury the help buffer >>>") (if (equal (setq unread-command-events (list (read-event))) '(?\ )) (progn (setq unread-command-events nil) (throw 'exit t))))) (let (up down both neither (standard (and (eq (key-binding " ") 'scroll-up) (eq (key-binding "\^?") 'scroll-down) (eq (key-binding "Q") 'electric-help-exit) (eq (key-binding "q") 'electric-help-exit)))) (Electric-command-loop 'exit (function (lambda () (let ((min (pos-visible-in-window-p (point-min))) (max (pos-visible-in-window-p (point-max)))) (cond ((and min max) (cond (standard "Press Q to exit ") (neither) (t (setq neither (substitute-command-keys "Press \\[scroll-up] to exit "))))) (min (cond (standard "Press SPC to scroll, Q to exit ") (up) (t (setq up (substitute-command-keys "Press \\[scroll-up] to scroll; \\[electric-help-exit] to exit "))))) (max (cond (standard "Press DEL to scroll back, Q to exit ") (down) (t (setq down (substitute-command-keys "Press \\[scroll-down] to scroll back, \\[scroll-up] to exit "))))) (t (cond (standard "Press SPC to scroll, DEL to scroll back, Q to exit ") (both) (t (setq both (substitute-command-keys "Press \\[scroll-up] to scroll, \\[scroll-down] to scroll back, \\[electric-help-exit] to exit "))))))))) t)))) ;(defun electric-help-scroll-up (arg) ; ">>>Doc" ; (interactive "P") ; (if (and (null arg) (pos-visible-in-window-p (point-max))) ; (electric-help-exit) ; (scroll-up arg))) (defun electric-help-exit () ">>>Doc" (interactive) (throw 'exit t)) (defun electric-help-retain () "Exit `electric-help', retaining the current window/buffer configuration. \(The *Help* buffer will not be selected, but \\[switch-to-buffer-other-window] RET will select it.)" (interactive) (throw 'exit '(retain))) (defun electric-help-undefined () (interactive) (error "%s is undefined -- Press %s to exit" (mapconcat 'single-key-description (this-command-keys) " ") (if (eq (key-binding "Q") 'electric-help-exit) "Q" (substitute-command-keys "\\[electric-help-exit]")))) ;>>> this needs to be hairified (recursive help, anybody?) (defun electric-help-help () (interactive) (if (and (eq (key-binding "Q") 'electric-help-exit) (eq (key-binding " ") 'scroll-up) (eq (key-binding "\^?") 'scroll-down)) (message "SPC scrolls forward, DEL scrolls back, Q exits and burys help buffer") ;; to give something for user to look at while slow substitute-cmd-keys ;; grinds away (message "Help...") (message "%s" (substitute-command-keys "\\[scroll-up] scrolls forward, \\[scroll-down] scrolls back, \\[electric-help-exit] exits."))) (sit-for 2)) (defun electric-helpify (fun) (let ((name "*Help*")) (if (save-window-excursion ;; kludge-o-rama (let* ((p (symbol-function 'print-help-return-message)) (b (get-buffer name)) (m (buffer-modified-p b))) (and b (not (get-buffer-window b)) (setq b nil)) (unwind-protect (progn (message "%s..." (capitalize (symbol-name fun))) ;; with-output-to-temp-buffer marks the buffer as unmodified. ;; kludging excessively and relying on that as some sort ;; of indication leads to the following abomination... ;;>> This would be doable without such icky kludges if either ;;>> (a) there were a function to read the interactive ;;>> args for a command and return a list of those args. ;;>> (To which one would then just apply the command) ;;>> (The only problem with this is that interactive-p ;;>> would break, but that is such a misfeature in ;;>> any case that I don't care) ;;>> It is easy to do this for emacs-lisp functions; ;;>> the only problem is getting the interactive spec ;;>> for subrs ;;>> (b) there were a function which returned a ;;>> modification-tick for a buffer. One could tell ;;>> whether a buffer had changed by whether the ;;>> modification-tick were different. ;;>> (Presumably there would have to be a way to either ;;>> restore the tick to some previous value, or to ;;>> suspend updating of the tick in order to allow ;;>> things like momentary-string-display) (and b (save-excursion (set-buffer b) (set-buffer-modified-p t))) (fset 'print-help-return-message 'ignore) (call-interactively fun) (and (get-buffer name) (get-buffer-window (get-buffer name)) (or (not b) (not (eq b (get-buffer name))) (not (buffer-modified-p b))))) (fset 'print-help-return-message p) (and b (buffer-name b) (save-excursion (set-buffer b) (set-buffer-modified-p m)))))) (with-electric-help 'ignore name t)))) (defun electric-describe-key () (interactive) (electric-helpify 'describe-key)) (defun electric-describe-mode () (interactive) (electric-helpify 'describe-mode)) (defun electric-view-lossage () (interactive) (electric-helpify 'view-lossage)) ;(defun electric-help-for-help () ; "See help-for-help" ; (interactive) ; ) (defun electric-describe-function () (interactive) (electric-helpify 'describe-function)) (defun electric-describe-variable () (interactive) (electric-helpify 'describe-variable)) (defun electric-describe-bindings () (interactive) (electric-helpify 'describe-bindings)) (defun electric-describe-syntax () (interactive) (electric-helpify 'describe-syntax)) (defun electric-command-apropos () (interactive) (electric-helpify 'command-apropos)) ;(define-key help-map "a" 'electric-command-apropos) ;;;; ehelp-map (defvar ehelp-map ()) (if ehelp-map nil (let ((map (copy-keymap help-map))) (substitute-key-definition 'describe-key 'electric-describe-key map) (substitute-key-definition 'describe-mode 'electric-describe-mode map) (substitute-key-definition 'view-lossage 'electric-view-lossage map) (substitute-key-definition 'describe-function 'electric-describe-function map) (substitute-key-definition 'describe-variable 'electric-describe-variable map) (substitute-key-definition 'describe-bindings 'electric-describe-bindings map) (substitute-key-definition 'describe-syntax 'electric-describe-syntax map) (setq ehelp-map map) (fset 'ehelp-command map))) ;; Do (define-key global-map "\C-h" 'ehelp-command) if you want to win (provide 'ehelp) ;;; ehelp.el ends here