code.delx.au - gnu-emacs/blob - lisp/map-ynp.el

   1 ;;; map-ynp.el --- General-purpose boolean question-asker.
   2
   3 ;;; Copyright (C) 1991, 1992, 1993 Free Software Foundation, Inc.
   4
   5 ;; Author: Roland McGrath <roland@gnu.ai.mit.edu>
   6 ;; Keywords: lisp, extensions
   7
   8 ;;; This program 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 2, or (at your option)
  11 ;;; any later version.
  12 ;;;
  13 ;;; This program 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 ;;; A copy of the GNU General Public License can be obtained from this
  19 ;;; program's author (send electronic mail to roland@ai.mit.edu) or from
  20 ;;; the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA
  21 ;;; 02139, USA.
  22
  23 ;;; Commentary:
  24
  25 ;;; map-y-or-n-p is a general-purpose question-asking function.
  26 ;;; It asks a series of y/n questions (a la y-or-n-p), and decides to
  27 ;;; applies an action to each element of a list based on the answer.
  28 ;;; The nice thing is that you also get some other possible answers
  29 ;;; to use, reminiscent of query-replace: ! to answer y to all remaining
  30 ;;; questions; ESC or q to answer n to all remaining questions; . to answer
  31 ;;; y once and then n for the remainder; and you can get help with C-h.
  32
  33 ;;; Code:
  34
  35 ;;;###autoload
  36 (defun map-y-or-n-p (prompter actor list &optional help action-alist
  37                               no-cursor-in-echo-area)
  38   "Ask a series of boolean questions.
  39 Takes args PROMPTER ACTOR LIST, and optional args HELP and ACTION-ALIST.
  40
  41 LIST is a list of objects, or a function of no arguments to return the next
  42 object or nil.
  43
  44 If PROMPTER is a string, the prompt is \(format PROMPTER OBJECT\).  If not
  45 a string, PROMPTER is a function of one arg (an object from LIST), which
  46 returns a string to be used as the prompt for that object.  If the return
  47 value is not a string, it is eval'd to get the answer; it may be nil to
  48 ignore the object, t to act on the object without asking the user, or a
  49 form to do a more complex prompt.
  50
  51 ACTOR is a function of one arg (an object from LIST),
  52 which gets called with each object that the user answers `yes' for.
  53
  54 If HELP is given, it is a list (OBJECT OBJECTS ACTION),
  55 where OBJECT is a string giving the singular noun for an elt of LIST;
  56 OBJECTS is the plural noun for elts of LIST, and ACTION is a transitive
  57 verb describing ACTOR.  The default is \(\"object\" \"objects\" \"act on\"\).
  58
  59 At the prompts, the user may enter y, Y, or SPC to act on that object;
  60 n, N, or DEL to skip that object; ! to act on all following objects;
  61 ESC or q to exit (skip all following objects); . (period) to act on the
  62 current object and then exit; or \\[help-command] to get help.
  63
  64 If ACTION-ALIST is given, it is an alist (KEY FUNCTION HELP) of extra keys
  65 that will be accepted.  KEY is a character; FUNCTION is a function of one
  66 arg (an object from LIST); HELP is a string.  When the user hits KEY,
  67 FUNCTION is called.  If it returns non-nil, the object is considered
  68 \"acted upon\", and the next object from LIST is processed.  If it returns
  69 nil, the prompt is repeated for the same object.
  70
  71 Final optional argument NO-CURSOR-IN-ECHO-AREA non-nil says not to set
  72 `cursor-in-echo-area' while prompting.
  73
  74 This function uses `query-replace-map' to define the standard responses,
  75 but not all of the responses which `query-replace' understands
  76 are meaningful here.
  77
  78 Returns the number of actions taken."
  79   (let* ((user-keys (if action-alist
  80                         (concat (mapconcat (function
  81                                             (lambda (elt)
  82                                               (key-description
  83                                                (char-to-string (car elt)))))
  84                                            action-alist ", ")
  85                                 " ")
  86                       ""))
  87          ;; Make a map that defines each user key as a vector containing
  88          ;; its definition.
  89          (map (cons 'keymap
  90                     (append (mapcar (lambda (elt)
  91                                       (cons (car elt) (vector (nth 1 elt))))
  92                                     action-alist)
  93                             query-replace-map)))
  94          (actions 0)
  95          prompt char elt tail def delayed-switch-frame
  96          (next (if (or (and list (symbolp list))
  97                        (subrp list)
  98                        (byte-code-function-p list)
  99                        (and (consp list)
 100                             (eq (car list) 'lambda)))
 101                    (function (lambda ()
 102                                (setq elt (funcall list))))
 103                  (function (lambda ()
 104                              (if list
 105                                  (progn
 106                                    (setq elt (car list)
 107                                          list (cdr list))
 108                                    t)
 109                                nil))))))
 110     (unwind-protect
 111         (progn
 112           (if (stringp prompter)
 113               (setq prompter (` (lambda (object)
 114                                   (format (, prompter) object)))))
 115           (while (funcall next)
 116             (setq prompt (funcall prompter elt))
 117             (if (stringp prompt)
 118                 (progn
 119                   (setq quit-flag nil)
 120                   ;; Prompt the user about this object.
 121                   (let ((cursor-in-echo-area (not no-cursor-in-echo-area)))
 122                     (message "%s(y, n, !, ., q, %sor %s) "
 123                              prompt user-keys
 124                              (key-description (vector help-char)))
 125                     (setq char (read-event)))
 126                   ;; Show the answer to the question.
 127                   (message "%s(y, n, !, ., q, %sor %s) %s"
 128                            prompt user-keys
 129                            (key-description (vector help-char))
 130                            (single-key-description char))
 131                   (setq def (lookup-key map (vector char)))
 132                   (cond ((eq def 'exit)
 133                          (setq next (function (lambda () nil))))
 134                         ((eq def 'act)
 135                          ;; Act on the object.
 136                          (funcall actor elt)
 137                          (setq actions (1+ actions)))
 138                         ((eq def 'skip)
 139                          ;; Skip the object.
 140                          )
 141                         ((eq def 'act-and-exit)
 142                          ;; Act on the object and then exit.
 143                          (funcall actor elt)
 144                          (setq actions (1+ actions)
 145                                next (function (lambda () nil))))
 146                         ((eq def 'quit)
 147                          (setq quit-flag t)
 148                          (setq next (` (lambda ()
 149                                          (setq next '(, next))
 150                                          '(, elt)))))
 151                         ((eq def 'automatic)
 152                          ;; Act on this and all following objects.
 153                          (if (eval (funcall prompter elt))
 154                              (progn
 155                                (funcall actor elt)
 156                                (setq actions (1+ actions))))
 157                          (while (funcall next)
 158                            (if (eval (funcall prompter elt))
 159                                (progn
 160                                  (funcall actor elt)
 161                                  (setq actions (1+ actions))))))
 162                         ((eq def 'help)
 163                          (with-output-to-temp-buffer "*Help*"
 164                            (princ
 165                             (let ((object (if help (nth 0 help) "object"))
 166                                   (objects (if help (nth 1 help) "objects"))
 167                                   (action (if help (nth 2 help) "act on")))
 168                               (concat
 169                                (format "Type SPC or `y' to %s the current %s;
 170 DEL or `n' to skip the current %s;
 171 ! to %s all remaining %s;
 172 ESC or `q' to exit;\n"
 173                                        action object object action objects)
 174                                       (mapconcat (function
 175                                                   (lambda (elt)
 176                                                     (format "%c to %s"
 177                                                             (nth 0 elt)
 178                                                             (nth 2 elt))))
 179                                                  action-alist
 180                                                  ";\n")
 181                                       (if action-alist ";\n")
 182                                       (format "or . (period) to %s \
 183 the current %s and exit."
 184                                               action object)))))
 185
 186                          (setq next (` (lambda ()
 187                                          (setq next '(, next))
 188                                          '(, elt)))))
 189                         ((vectorp def)
 190                          ;; A user-defined key.
 191                          (if (funcall (aref def 0) elt) ;Call its function.
 192                              ;; The function has eaten this object.
 193                              (setq actions (1+ actions))
 194                            ;; Regurgitated; try again.
 195                            (setq next (` (lambda ()
 196                                            (setq next '(, next))
 197                                            '(, elt))))))
 198                         ((and (consp char)
 199                               (eq (car char) 'switch-frame))
 200                          ;; switch-frame event.  Put it off until we're done.
 201                          (setq delayed-switch-frame char)
 202                          (setq next (` (lambda ()
 203                                          (setq next '(, next))
 204                                          '(, elt)))))
 205                         (t
 206                          ;; Random char.
 207                          (message "Type %s for help."
 208                                   (key-description (vector help-char)))
 209                          (beep)
 210                          (sit-for 1)
 211                          (setq next (` (lambda ()
 212                                          (setq next '(, next))
 213                                          '(, elt)))))))
 214               (if (eval prompt)
 215                   (progn
 216                     (funcall actor elt)
 217                     (setq actions (1+ actions)))))))
 218       (if delayed-switch-frame
 219           (setq unread-command-events
 220                 (cons delayed-switch-frame unread-command-events))))
 221     ;; Clear the last prompt from the minibuffer.
 222     (message "")
 223     ;; Return the number of actions that were taken.
 224     actions))
 225
 226 ;;; map-ynp.el ends here