4.4BSD/usr/src/contrib/emacs-18.57/lisp/ehelp.el
;; Copyright (C) 1986 Free Software Foundation, Inc.
;; 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.
(require 'electric)
(provide 'ehelp)
(defvar electric-help-map ()
"Keymap defining commands available whilst scrolling
through a buffer in electric-help-mode")
(put 'electric-help-undefined 'suppress-keymap t)
(if electric-help-map
()
(let ((map (make-keymap)))
(fillarray 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 initialise
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 (ie 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))
(two nil))
(save-window-excursion
(save-excursion
(if one (goto-char (window-start (selected-window))))
(let ((pop-up-windows t))
(pop-to-buffer buffer))
(unwind-protect
(progn
(save-excursion
(set-buffer buffer)
(electric-help-mode)
(setq buffer-read-only nil)
(or noerase (erase-buffer)))
(let ((standard-output buffer))
(if (funcall thunk)
()
(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)
(setq two (electric-help-command-loop))
(cond ((eq (car-safe two) 'retain)
(setq two (vector (window-height (selected-window))
(window-start (selected-window))
(window-hscroll (selected-window))
(point))))
(t (setq two nil))))
(message "")
(set-buffer buffer)
(setq buffer-read-only nil)
(condition-case ()
(funcall (or default-major-mode 'fundamental-mode))
(error nil)))))
(if two
(let ((pop-up-windows t)
tem)
(pop-to-buffer buffer)
(setq tem (- (window-height (selected-window)) (elt two 0)))
(if (> tem 0) (shrink-window tem))
(set-window-start (selected-window) (elt two 1) t)
(set-window-hscroll (selected-window) (elt two 2))
(goto-char (elt two 3)))
;;>> 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 (= (setq unread-command-char (read-char)) ?\ )
(progn (setq unread-command-char -1)
(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 conifiguration.
\(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)
; (let* ((keys (this-command-keys))
; (n (length keys)))
; (if (or (= n 1)
; (and (= n 2)
; meta-flag
; (eq (aref keys 0) meta-prefix-char)))
; (setq unread-command-char last-input-char
; current-prefix-arg prefix-arg)
; ;;>>> I don't care.
; ;;>>> The emacs command-loop is too much pure pain to
; ;;>>> duplicate
; ))
; (throw 'exit t))
(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