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Java > Open Source Codes > org > armedbear > lisp > simple_list_remove_duplicates


1 /*
2  * simple_list_remove_duplicates.java
3  *
4  * Copyright (C) 2004 Peter Graves
5  * $Id: simple_list_remove_duplicates.java,v 1.1 2004/03/13 17:49:00 piso Exp $
6  *
7  * This program is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU General Public License
9  * 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 // ### simple-list-remove-duplicates
25 public final class simple_list_remove_duplicates extends Primitive1
26 {
27     private simple_list_remove_duplicates()
28     {
29         super("simple-list-remove-duplicates", PACKAGE_SYS, false, "list");
30     }
31
32     public LispObject execute(LispObject list) throws ConditionThrowable
33     {
34         LispObject result = NIL;
35         while (list != NIL) {
36             LispObject item = list.car();
37             boolean duplicate = false;
38             LispObject tail = list.cdr();
39             while (tail != NIL) {
40                 if (item.eql(tail.car())) {
41                     duplicate = true;
42                     break;
43                 }
44                 tail = tail.cdr();
45             }
46             if (!duplicate)
47                 result = new Cons(item, result);
48             list = list.cdr();
49         }
50         return result.nreverse();
51     }
52
53     private static final Primitive1 SIMPLE_LIST_REMOVE_DUPLICATES =
54         new simple_list_remove_duplicates();
55 }
56
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