/*
* Copyright (c) 2003, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package sun.misc;
/**
* Utility class for small LRU caches.
*
* @author Mark Reinhold
*/
public abstract class LRUCache<N,V> {
private V[] oa = null;
private final int size;
public LRUCache(int size) {
this.size = size;
}
abstract protected V create(N name);
abstract protected boolean hasName(V ob, N name);
public static void moveToFront(Object[] oa, int i) {
Object ob = oa[i];
for (int j = i; j > 0; j--)
oa[j] = oa[j - 1];
oa[0] = ob;
}
public V forName(N name) {
if (oa == null) {
oa = (V[])new Object[size];
} else {
for (int i = 0; i < oa.length; i++) {
V ob = oa[i];
if (ob == null)
continue;
if (hasName(ob, name)) {
if (i > 0)
moveToFront(oa, i);
return ob;
}
}
}
// Create a new object
V ob = create(name);
oa[oa.length - 1] = ob;
moveToFront(oa, oa.length - 1);
return ob;
}
}