1 /*
 2  * Copyright (c) 2024-26, Oracle and/or its affiliates. All rights reserved.
 3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 4  *
 5  * This code is free software; you can redistribute it and/or modify it
 6  * under the terms of the GNU General Public License version 2 only, as
 7  * published by the Free Software Foundation.  Oracle designates this
 8  * particular file as subject to the "Classpath" exception as provided
 9  * by Oracle in the LICENSE file that accompanied this code.
10  *
11  * This code is distributed in the hope that it will be useful, but WITHOUT
12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14  * version 2 for more details (a copy is included in the LICENSE file that
15  * accompanied this code).
16  *
17  * You should have received a copy of the GNU General Public License version
18  * 2 along with this work; if not, write to the Free Software Foundation,
19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20  *
21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22  * or visit www.oracle.com if you need additional information or have any
23  * questions.
24  */
25 package optkl.util;
26 
27 import java.util.LinkedHashMap;
28 import java.util.Map;
29 import java.util.function.Consumer;
30 
31 public class Interner<N> {
32     protected final Map<N, N> interned = new LinkedHashMap<>();
33 
34     public N intern(N n, Consumer<N> ifAbsent) {
35         if (!interned.containsKey(n)) {
36             interned.put(n, n);
37             ifAbsent.accept(n);
38         }
39         return interned.get(n);
40     }
41 
42     public boolean add(N n) {
43         boolean[] added ={false};
44         intern(n,_->added[0]=true);
45         return added[0];
46     }
47 }