source: trunk/j/src/org/armedbear/lisp/multiple-value-bind.lisp @ 9266

Last change on this file since 9266 was 7351, checked in by piso, 17 years ago

Use traditional implementation of M-V-B in terms of M-V-C (from CMUCL).

File size: 1.8 KB
Line 
1;;; multiple-value-bind.lisp
2;;;
3;;; Copyright (C) 2004 Peter Graves
4;;; $Id: multiple-value-bind.lisp,v 1.2 2004-08-02 15:07:38 piso Exp $
5;;;
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.
10;;;
11;;; This program is distributed in the hope that it will be useful,
12;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
13;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14;;; GNU General Public License for more details.
15;;;
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.
19
20;;; Adapted from CMUCL.
21
22(in-package "SYSTEM")
23
24;; The traditional implementation of M-V-B in terms of M-V-C. ABCL implements
25;; M-V-B as a special form in the interpreter, and ABCL's compiler handles it
26;; specifically too, so this code is only here to support code walkers and the
27;; like, as required by ANSI.
28(defmacro multiple-value-bind (varlist value-form &body body)
29  (unless (and (listp varlist) (every #'symbolp varlist))
30    (error 'program-error
31           :format-control "Variable list is not a list of symbols: ~S."
32           :format-arguments (list varlist)))
33  (if (= (length varlist) 1)
34      `(let ((,(car varlist) ,value-form))
35   ,@body)
36      (let ((ignore (gensym)))
37  `(multiple-value-call #'(lambda (&optional ,@(mapcar #'list varlist) &rest ,ignore)
38                                 (declare (ignore ,ignore))
39                                 ,@body)
40                              ,value-form))))
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