source: trunk/abcl/src/org/armedbear/lisp/shiftf.lisp @ 14215

Last change on this file since 14215 was 11391, checked in by vvoutilainen, 12 years ago

ABCL license is GPL + Classpath exception. This was intended
by Peter Graves, the original author. For reference, see

  • Property svn:eol-style set to native
  • Property svn:keywords set to Id
File size: 3.4 KB
1;;; shiftf.lisp
3;;; Copyright (C) 2003-2004 Peter Graves
4;;; $Id: shiftf.lisp 11391 2008-11-15 22:38:34Z vvoutilainen $
6;;; This program is free software; you can redistribute it and/or
7;;; modify it under the terms of the GNU General Public License
8;;; as published by the Free Software Foundation; either version 2
9;;; of the License, or (at your option) any later version.
11;;; This program is distributed in the hope that it will be useful,
12;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
14;;; GNU General Public License for more details.
16;;; You should have received a copy of the GNU General Public License
17;;; along with this program; if not, write to the Free Software
18;;; Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
20;;; As a special exception, the copyright holders of this library give you
21;;; permission to link this library with independent modules to produce an
22;;; executable, regardless of the license terms of these independent
23;;; modules, and to copy and distribute the resulting executable under
24;;; terms of your choice, provided that you also meet, for each linked
25;;; independent module, the terms and conditions of the license of that
26;;; module.  An independent module is a module which is not derived from
27;;; or based on this library.  If you modify this library, you may extend
28;;; this exception to your version of the library, but you are not
29;;; obligated to do so.  If you do not wish to do so, delete this
30;;; exception statement from your version.
32;;; From CMUCL.
34(in-package "SYSTEM")
36(require '#:collect)
38(defmacro shiftf (&rest args &environment env)
39  "One or more SETF-style place expressions, followed by a single
40   value expression.  Evaluates all of the expressions in turn, then
41   assigns the value of each expression to the place on its left,
42   returning the value of the leftmost."
43  (when args
44    (collect ((let*-bindings) (mv-bindings) (setters) (getters))
45             ;; The last arg isn't necessarily a place, so we have to handle
46             ;; that separately.
47             (dolist (arg (butlast args))
48               (multiple-value-bind
49                 (temps subforms store-vars setter getter)
50                 (get-setf-expansion arg env)
51                 (loop
52                   for temp in temps
53                   for subform in subforms
54                   do (let*-bindings `(,temp ,subform)))
55                 (mv-bindings store-vars)
56                 (setters setter)
57                 (getters getter)))
58             ;; Handle the last arg specially here.  Just put something to
59             ;; force the setter so the setter for the previous var gets set,
60             ;; and the getter is just the last arg itself.
61             (setters nil)
62             (getters (car (last args)))
64             (labels ((thunk (mv-bindings getters)
65                             (if mv-bindings
66                                 `((multiple-value-bind
67                                     ,(car mv-bindings)
68                                     ,(car getters)
69                                     ,@(thunk (cdr mv-bindings) (cdr getters))))
70                                 `(,@(butlast (setters))))))
71                     `(let* ,(let*-bindings)
72                        (multiple-value-bind ,(car (mv-bindings))
73                          ,(car (getters))
74                          ,@(thunk (mv-bindings) (cdr (getters)))
75                          (values ,@(car (mv-bindings)))))))))
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