| /* |
| * 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) { |
| @SuppressWarnings("unchecked") |
| V[] temp = (V[])new Object[size]; |
| oa = temp; |
| } 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; |
| } |
| |
| } |