Showing the changes to java/pkg/sun/misc/LRUCache.java (1 of 18352 files). Show all
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| 1 | +/* | |
| 2 | + * Copyright (c) 2003, 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 | + | |
| 26 | +package sun.misc; | |
| 27 | + | |
| 28 | +/** | |
| 29 | + * Utility class for small LRU caches. | |
| 30 | + * | |
| 31 | + * @author Mark Reinhold | |
| 32 | + */ | |
| 33 | +public abstract class LRUCache<N,V> { | |
| 34 | + | |
| 35 | + private V[] oa = null; | |
| 36 | + private final int size; | |
| 37 | + | |
| 38 | + public LRUCache(int size) { | |
| 39 | + this.size = size; | |
| 40 | + } | |
| 41 | + | |
| 42 | + abstract protected V create(N name); | |
| 43 | + | |
| 44 | + abstract protected boolean hasName(V ob, N name); | |
| 45 | + | |
| 46 | + public static void moveToFront(Object[] oa, int i) { | |
| 47 | + Object ob = oa[i]; | |
| 48 | + for (int j = i; j > 0; j--) | |
| 49 | + oa[j] = oa[j - 1]; | |
| 50 | + oa[0] = ob; | |
| 51 | + } | |
| 52 | + | |
| 53 | + public V forName(N name) { | |
| 54 | + if (oa == null) { | |
| 55 | + oa = (V[])new Object[size]; | |
| 56 | + } else { | |
| 57 | + for (int i = 0; i < oa.length; i++) { | |
| 58 | + V ob = oa[i]; | |
| 59 | + if (ob == null) | |
| 60 | + continue; | |
| 61 | + if (hasName(ob, name)) { | |
| 62 | + if (i > 0) | |
| 63 | + moveToFront(oa, i); | |
| 64 | + return ob; | |
| 65 | + } | |
| 66 | + } | |
| 67 | + } | |
| 68 | + | |
| 69 | + // Create a new object | |
| 70 | + V ob = create(name); | |
| 71 | + oa[oa.length - 1] = ob; | |
| 72 | + moveToFront(oa, oa.length - 1); | |
| 73 | + return ob; | |
| 74 | + } | |
| 75 | + | |
| 76 | +} | |