lisp/emacs-lisp/helper.el

   1 ;;; helper.el --- utility help package supporting help in electric modes
   2
   3 ;; Copyright (C) 1985 Free Software Foundation, Inc.
   4 ;; Principal author K. Shane Hartman
   5
   6 ;; This file is part of GNU Emacs.
   7
   8 ;; GNU Emacs is free software; you can redistribute it and/or modify
   9 ;; it under the terms of the GNU General Public License as published by
  10 ;; the Free Software Foundation; either version 1, or (at your option)
  11 ;; any later version.
  12
  13 ;; GNU Emacs is distributed in the hope that it will be useful,
  14 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 ;; GNU General Public License for more details.
  17
  18 ;; You should have received a copy of the GNU General Public License
  19 ;; along with GNU Emacs; see the file COPYING.  If not, write to
  20 ;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
  21
  22
  23 ; hey, here's a helping hand.
  24
  25 ;; Bind this to a string for <blank> in "... Other keys <blank>".
  26 ;; Helper-help uses this to construct help string when scrolling.
  27 ;; Defaults to "return"
  28 (defvar Helper-return-blurb nil)
  29
  30 ;; Keymap implementation doesn't work too well for non-standard loops.
  31 ;; But define it anyway for those who can use it.  Non-standard loops
  32 ;; will probably have to use Helper-help.  You can't autoload the
  33 ;; keymap either.
  34
  35
  36 (defvar Helper-help-map nil)
  37 (if Helper-help-map
  38     nil
  39   (setq Helper-help-map (make-keymap))
  40   ;(fillarray Helper-help-map 'undefined)
  41   (define-key Helper-help-map "m" 'Helper-describe-mode)
  42   (define-key Helper-help-map "b" 'Helper-describe-bindings)
  43   (define-key Helper-help-map "c" 'Helper-describe-key-briefly)
  44   (define-key Helper-help-map "k" 'Helper-describe-key)
  45   ;(define-key Helper-help-map "f" 'Helper-describe-function)
  46   ;(define-key Helper-help-map "v" 'Helper-describe-variable)
  47   (define-key Helper-help-map "?" 'Helper-help-options)
  48   (define-key Helper-help-map (char-to-string help-char) 'Helper-help-options)
  49   (fset 'Helper-help-map Helper-help-map))
  50
  51 (defun Helper-help-scroller ()
  52   (let ((blurb (or (and (boundp 'Helper-return-blurb)
  53                         Helper-return-blurb)
  54                    "return")))
  55     (save-window-excursion
  56       (goto-char (window-start (selected-window)))
  57       (if (get-buffer-window "*Help*")
  58           (pop-to-buffer "*Help*")
  59         (switch-to-buffer "*Help*"))
  60       (goto-char (point-min))
  61       (let ((continue t) state)
  62         (while continue
  63           (setq state (+ (* 2 (if (pos-visible-in-window-p (point-max)) 1 0))
  64                          (if (pos-visible-in-window-p (point-min)) 1 0)))
  65           (message
  66             (nth state
  67                  '("Space forward, Delete back. Other keys %s"
  68                    "Space scrolls forward. Other keys %s"
  69                    "Delete scrolls back. Other keys %s"
  70                    "Type anything to %s"))
  71             blurb)
  72           (setq continue (read-char))
  73           (cond ((and (memq continue '(?\ ?\C-v)) (< state 2))
  74                  (scroll-up))
  75                 ((= continue ?\C-l)
  76                  (recenter))
  77                 ((and (= continue ?\177) (zerop (% state 2)))
  78                  (scroll-down))
  79                 (t (setq continue nil))))))))
  80
  81 (defun Helper-help-options ()
  82   "Describe help options."
  83   (interactive)
  84   (message "c (key briefly), m (mode), k (key), b (bindings)")
  85   ;(message "c (key briefly), m (mode), k (key), v (variable), f (function)")
  86   (sit-for 4))
  87
  88 (defun Helper-describe-key-briefly (key)
  89   "Briefly describe binding of KEY."
  90   (interactive "kDescribe key briefly: ")
  91   (describe-key-briefly key)
  92   (sit-for 4))
  93
  94 (defun Helper-describe-key (key)
  95   "Describe binding of KEY."
  96   (interactive "kDescribe key: ")
  97   (save-window-excursion (describe-key key))
  98   (Helper-help-scroller))
  99
 100 (defun Helper-describe-function ()
 101   "Describe a function.  Name read interactively."
 102   (interactive)
 103   (save-window-excursion (call-interactively 'describe-function))
 104   (Helper-help-scroller))
 105
 106 (defun Helper-describe-variable ()
 107   "Describe a variable.  Name read interactively."
 108   (interactive)
 109   (save-window-excursion (call-interactively 'describe-variable))
 110   (Helper-help-scroller))
 111
 112 (defun Helper-describe-mode ()
 113   "Describe the current mode."
 114   (interactive)
 115   (let ((name mode-name)
 116         (documentation (documentation major-mode)))
 117     (save-excursion
 118       (set-buffer (get-buffer-create "*Help*"))
 119       (erase-buffer)
 120       (insert name " Mode\n" documentation)))
 121   (Helper-help-scroller))
 122
 123 ;;;###autoload
 124 (defun Helper-describe-bindings ()
 125   "Describe local key bindings of current mode."
 126   (interactive)
 127   (message "Making binding list...")
 128   (save-window-excursion (describe-bindings))
 129   (Helper-help-scroller))
 130
 131 ;;;###autoload
 132 (defun Helper-help ()
 133   "Provide help for current mode."
 134   (interactive)
 135   (let ((continue t) c)
 136     (while continue
 137       (message "Help (Type ? for further options)")
 138       (setq c (char-to-string (downcase (read-char))))
 139       (setq c (lookup-key Helper-help-map c))
 140       (cond ((eq c 'Helper-help-options)
 141              (Helper-help-options))
 142             ((commandp c)
 143              (call-interactively c)
 144              (setq continue nil))
 145             (t
 146              (ding)
 147              (setq continue nil))))))
 148
 149 (provide 'helper)
 150
 151 ;;; helper.el ends here