01: /*
02: * assq.java
03: *
04: * Copyright (C) 2003 Peter Graves
05: * $Id: assq.java,v 1.2 2003/12/13 00:58:51 piso Exp $
06: *
07: * This program is free software; you can redistribute it and/or
08: * modify it under the terms of the GNU General Public License
09: * as published by the Free Software Foundation; either version 2
10: * of the License, or (at your option) any later version.
11: *
12: * This program is distributed in the hope that it will be useful,
13: * but WITHOUT ANY WARRANTY; without even the implied warranty of
14: * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15: * GNU General Public License for more details.
16: *
17: * You should have received a copy of the GNU General Public License
18: * along with this program; if not, write to the Free Software
19: * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
20: */
21:
22: package org.armedbear.lisp;
23:
24: // ### assq item alist => entry
25: public final class assq extends Primitive2 {
26: private assq() {
27: super ("assq", PACKAGE_EXT);
28: }
29:
30: public LispObject execute(LispObject item, LispObject alist)
31: throws ConditionThrowable {
32: while (alist != NIL) {
33: LispObject cons = alist.car();
34: if (cons instanceof Cons) {
35: if (cons.car() == item)
36: return cons;
37: } else if (cons != NIL)
38: return signal(new TypeError(cons, "list"));
39: alist = alist.cdr();
40: }
41: return NIL;
42: }
43:
44: private static final assq ASSQ = new assq();
45: }
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