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;;; ehelp.el --- bindings for electric-help mode -*- lexical-binding: t -*-
;; Copyright (C) 1986, 1995, 2000-2015 Free Software Foundation, Inc.
;; Author: Richard Mlynarik
;; (according to ack.texi and authors.el)
;; Maintainer: emacs-devel@gnu.org
;; 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 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 <http://www.gnu.org/licenses/>.
;;; Commentary:
;; This package provides a pre-packaged `Electric Help Mode' for
;; browsing Emacs 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.
;; To make this the default, you must do
;; (require 'ehelp)
;; (define-key global-map "\C-h" 'ehelp-command)
;; (define-key global-map [help] 'ehelp-command)
;; (define-key global-map [f1] 'ehelp-command)
;;; Code:
(require 'electric)
(defvar electric-help-form-to-execute nil)
(defgroup electric-help ()
"Electric help facility."
:version "21.1"
:group 'help)
(defcustom electric-help-shrink-window t
"If set, adjust help window sizes to buffer sizes when displaying help."
:type 'boolean
:group 'electric-help)
(defcustom electric-help-mode-hook nil
"Hook run by `with-electric-help' after initializing the buffer."
:type 'hook
:group 'electric-help)
(put 'electric-help-undefined 'suppress-keymap t)
(defvar electric-help-map
(let ((map (make-keymap)))
;; FIXME fragile. Should derive from help-mode-map in a smarter way.
(set-keymap-parent map button-buffer-map)
;; allow all non-self-inserting keys - search, scroll, etc, but
;; let M-x and C-x exit ehelp mode and retain buffer:
(suppress-keymap map)
(define-key map "\C-u" 'electric-help-undefined)
(define-key map [?\C-0] 'electric-help-undefined)
(define-key map [?\C-1] 'electric-help-undefined)
(define-key map [?\C-2] 'electric-help-undefined)
(define-key map [?\C-3] 'electric-help-undefined)
(define-key map [?\C-4] 'electric-help-undefined)
(define-key map [?\C-5] 'electric-help-undefined)
(define-key map [?\C-6] 'electric-help-undefined)
(define-key map [?\C-7] 'electric-help-undefined)
(define-key map [?\C-8] 'electric-help-undefined)
(define-key map [?\C-9] 'electric-help-undefined)
(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 [?\S-\ ] 'scroll-down)
(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)
(define-key map "r" 'electric-help-retain)
(define-key map "\ex" 'electric-help-execute-extended)
(define-key map "\C-x" 'electric-help-ctrl-x-prefix)
map)
"Keymap defining commands available in `electric-help-mode'.")
(defvar electric-help-orig-major-mode nil)
(make-variable-buffer-local 'electric-help-orig-major-mode)
(defun electric-help-mode ()
"`with-electric-help' temporarily places its buffer in this mode.
\(On exit from `with-electric-help', the original `major-mode' is restored.)"
(setq buffer-read-only t)
(setq electric-help-orig-major-mode major-mode)
(setq mode-name "Help")
(setq major-mode 'help-mode)
(setq mode-line-buffer-identification '(" Help: %b"))
(use-local-map electric-help-map)
(add-hook 'mouse-leave-buffer-hook 'electric-help-retain)
(view-mode -1)
;; this is done below in with-electric-help
;(run-hooks 'electric-help-mode-hook)
)
;;;###autoload
(defun with-electric-help (thunk &optional buffer noerase minheight)
"Pop up an \"electric\" help buffer.
THUNK is a function of no arguments which is called to initialize the
contents of BUFFER. BUFFER defaults to `*Help*'. BUFFER will be
erased before THUNK is called unless NOERASE is non-nil. THUNK will
be called while BUFFER is current and with `standard-output' bound to
the buffer specified by BUFFER.
If THUNK returns nil, we display BUFFER starting at the top, and shrink
the window to fit. If THUNK returns non-nil, we don't do those things.
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'. The window's height will
be at least MINHEIGHT if this value is non-nil.
If THUNK returns nil, we display BUFFER starting at the top, and
shrink the window to fit if `electric-help-shrink-window' is non-nil.
If THUNK returns non-nil, we don't do those things.
When the user exits (with `electric-help-exit', or otherwise), the help
buffer's window disappears (i.e., we use `save-window-excursion'), and
BUFFER is put back into its original major mode."
(setq buffer (get-buffer-create (or buffer "*Help*")))
(let ((one (one-window-p t))
(config (current-window-configuration))
(bury nil)
(electric-help-form-to-execute nil))
(unwind-protect
(save-excursion
(when one
(goto-char (window-start)))
(let ((pop-up-windows t))
(pop-to-buffer buffer))
(with-current-buffer buffer
(when (and minheight (< (window-height) minheight))
(enlarge-window (- minheight (window-height))))
(electric-help-mode)
(setq buffer-read-only nil)
(unless noerase
(erase-buffer)))
(let ((standard-output buffer))
(unless (funcall thunk)
(set-buffer buffer)
(set-buffer-modified-p nil)
(goto-char (point-min))
(when (and one electric-help-shrink-window)
(shrink-window-if-larger-than-buffer))))
(set-buffer buffer)
(run-hooks 'electric-help-mode-hook)
(setq buffer-read-only t)
(if (eq (car-safe (electric-help-command-loop)) 'retain)
(setq config (current-window-configuration))
(setq bury t))
;; Remove the hook.
(when (memq 'electric-help-retain mouse-leave-buffer-hook)
(remove-hook 'mouse-leave-buffer-hook 'electric-help-retain)))
(message "")
(set-buffer buffer)
(setq buffer-read-only nil)
;; Restore the original major mode saved by `electric-help-mode'.
;; We should really get a usable *Help* buffer when retaining
;; the electric one with `r'. The problem is that a simple
;; call to `help-mode' won't cut it; e.g. RET is bound wrong
;; afterwards (`View-scroll-line-forward' instead of `help-follow').
;; That's because Help mode should be set with `with-help-window'
;; instead of the direct call to `help-mode'. But at least
;; RET works correctly on links after using `help-mode'.
;; This is satisfactory enough.
(condition-case ()
(funcall (or electric-help-orig-major-mode 'fundamental-mode))
(error nil))
(set-window-configuration config)
(when bury
;;>> 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))
(if (functionp electric-help-form-to-execute)
(funcall electric-help-form-to-execute)
(eval electric-help-form-to-execute)))))
(defun electric-help-command-loop ()
(catch 'exit
(if (pos-visible-in-window-p (point-max))
(progn (message "%s" (substitute-command-keys "<<< Press Space to bury the help buffer, Press \\[electric-help-retain] to retain it >>>"))
(if (equal (setq unread-command-events (list (read-event)))
'(?\s))
(progn (setq unread-command-events nil)
(throw 'exit t)))))
(let (up down both neither
(standard (and (eq (key-binding " " nil t)
'scroll-up)
(eq (key-binding "\^?" nil t)
'scroll-down)
(eq (key-binding "q" nil t)
'electric-help-exit)
(eq (key-binding "r" nil t)
'electric-help-retain))))
(Electric-command-loop
'exit
(function (lambda ()
(sit-for 0) ;necessary if last command was end-of-buffer or
;beginning-of-buffer - otherwise pos-visible-in-window-p
;will yield a wrong result.
(let ((min (pos-visible-in-window-p (point-min)))
(max (pos-visible-in-window-p (1- (point-max)))))
(cond (isearch-mode 'noprompt)
((and min max)
(cond (standard "Press q to exit, r to retain ")
(neither)
(t (setq neither (substitute-command-keys "Press \\[electric-help-exit] to exit, \\[electric-help-retain] to retain ")))))
(min
(cond (standard "Press SPC to scroll, q to exit, r to retain ")
(up)
(t (setq up (substitute-command-keys "Press \\[scroll-up] to scroll, \\[electric-help-exit] to exit, \\[electric-help-retain] to retain ")))))
(max
(cond (standard "Press DEL to scroll back, q to exit, r to retain ")
(down)
(t (setq down (substitute-command-keys "Press \\[scroll-down] to scroll back, \\[electric-help-exit] to exit, \\[electric-help-retain] to retain ")))))
(t
(cond (standard "Press SPC to scroll, DEL to scroll back, q to exit, r to retain ")
(both)
(t (setq both (substitute-command-keys "Press \\[scroll-up] to scroll, \\[scroll-down] to scroll back, \\[electric-help-exit] to exit, \\[electric-help-retain] to retain ")))))))))
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 ()
"Exit `with-electric-help', restoring the previous window/buffer configuration.
\(The *Help* buffer will be buried.)"
(interactive)
;; Make sure that we don't throw twice, even if two events cause
;; calling this function:
(if (memq 'electric-help-retain mouse-leave-buffer-hook)
(progn
(remove-hook 'mouse-leave-buffer-hook 'electric-help-retain)
(throw 'exit t))))
(defun electric-help-retain ()
"Exit `with-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)
;; Make sure that we don't throw twice, even if two events cause
;; calling this function:
(if (memq 'electric-help-retain mouse-leave-buffer-hook)
(progn
(remove-hook 'mouse-leave-buffer-hook 'electric-help-retain)
(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" nil t) '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" nil t) 'electric-help-exit)
(eq (key-binding " " nil t) 'scroll-up)
(eq (key-binding "\^?" nil t) 'scroll-down)
(eq (key-binding "r" nil t) 'electric-help-retain))
(message "SPC scrolls up, DEL scrolls down, q exits burying help buffer, r exits")
(message "%s" (substitute-command-keys "\\[scroll-up] scrolls up, \\[scroll-down] scrolls down, \\[electric-help-exit] exits burying help buffer, \\[electric-help-retain] exits")))
(sit-for 2))
;;;###autoload
(defun electric-helpify (fun &optional name)
(let ((name (or name "*Help*")))
(if (save-window-excursion
;; kludge-o-rama
(let* ((p (symbol-function 'help-print-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
(with-current-buffer b
(set-buffer-modified-p t)))
(fset 'help-print-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 'help-print-return-message p)
(and b (buffer-name b)
(with-current-buffer b
(set-buffer-modified-p m))))))
(with-electric-help 'ignore name t))))
;; This is to be bound to M-x in ehelp mode. Retains ehelp buffer and then
;; continues with execute-extended-command.
(defun electric-help-execute-extended (_prefixarg)
(interactive "p")
(setq electric-help-form-to-execute
(lambda () (execute-extended-command nil)))
(electric-help-retain))
;; This is to be buond to C-x in ehelp mode. Retains ehelp buffer and then
;; continues with ctrl-x prefix.
(defun electric-help-ctrl-x-prefix (_prefixarg)
(interactive "p")
(setq electric-help-form-to-execute
(lambda ()
(message nil)
(setq unread-command-events
(append unread-command-events '(?\C-x)))))
(electric-help-retain))
(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 "*Apropos*"))
;(define-key help-map "a" 'electric-command-apropos)
(defun electric-apropos ()
(interactive)
(electric-helpify 'apropos))
;;;; ehelp-map
(defvar ehelp-map
(let ((map (copy-keymap help-map)))
(substitute-key-definition 'apropos 'electric-apropos map)
(substitute-key-definition 'command-apropos 'electric-command-apropos 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)
map))
;;;###(autoload 'ehelp-command "ehelp" "Prefix command for ehelp." t 'keymap)
(defalias 'ehelp-command ehelp-map)
(put 'ehelp-command 'documentation "Prefix command for ehelp.")
(provide 'ehelp)
;;; ehelp.el ends here
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