1 /* 2 * Copyright (c) 2002, 2018, 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. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 */ 23 24 package nsk.share.sysdict; 25 26 import nsk.share.*; 27 28 /** 29 * A binary tree of class loaders. 30 * 31 * @see TreeNodesDenotation 32 */ 33 public class ClassLoadersBTree { 34 /** 35 * Cannot instantiate while a tree root and height 36 * are not specified. 37 * 38 * @see #ClassLoadersBTree(ClassLoader,int) 39 */ ClassLoadersBTree()40 protected ClassLoadersBTree() { 41 } 42 43 /** 44 * Given the <tt>root</tt> loader, instantiate a binary tree 45 * of loaders up to the given tree <tt>height</tt>. 46 * 47 * @see #getHeight() 48 * @see #getRoot() 49 * @see #getLoader(String) 50 * @see #getLoader(int,int) 51 */ ClassLoadersBTree(ClassLoader root, int height)52 public ClassLoadersBTree(ClassLoader root, int height) { 53 if (height < 1) 54 throw new IllegalArgumentException("wrong height: " + height); 55 loaders = new ClassLoader [ height ] []; 56 for (int level=0; level<height; level++) 57 loaders[level] = new ClassLoader [1 << level]; 58 loaders[0][0] = root; 59 generateSubtree(""); 60 } generateSubtree(String name)61 private void generateSubtree(String name) { 62 int level = name.length(); 63 int height = loaders.length; 64 if (level+1 == height) 65 return; 66 String nameL = name + "L"; 67 String nameR = name + "R"; 68 int[] index = denotation.indexFor(name); 69 int[] indexL = denotation.indexFor(nameL); 70 int[] indexR = denotation.indexFor(nameR); 71 // assertion: index[0] == level 72 // assertion: indexL[0] == indexR[0] == level+1 73 int item = index[1]; 74 int itemL = indexL[1]; 75 int itemR = indexR[1]; 76 ClassLoader parent = loaders[level][item]; 77 ClassLoader childL = new DummyClassLoader(parent); 78 ClassLoader childR = new DummyClassLoader(parent); // another item 79 loaders[level+1][itemL] = childL; 80 loaders[level+1][itemR] = childR; 81 generateSubtree(nameL); 82 generateSubtree(nameR); 83 } 84 85 private ClassLoader loaders[][]; // loaders[0][0] is root 86 private Denotation denotation = new TreeNodesDenotation(); 87 88 /** 89 * Return the loader found at the given <tt>level</tt> of 90 * this loaders tree, and having the given <tt>item</tt> 91 * number at the enumeration of that <tt>level</tt>. 92 * 93 * <p>The value of <tt>level</tt> must be from <tt>0</tt> 94 * to <tt>getHeight()-1</tt>, and the <tt>item</tt> number 95 * must be from <tt>0</tt> to <tt>2<sup>level</sup>-1</tt>. 96 * 97 * @see #getHeight() 98 * @see #getRoot() 99 * @see #getLoader(String) 100 */ getLoader(int level, int item)101 public ClassLoader getLoader(int level, int item) { 102 return loaders[level][item]; 103 } 104 105 /** 106 * Return the loader having the giving <tt>name</tt> at 107 * the standard denotation of binary tree nodes. 108 * 109 * @see #getHeight() 110 * @see #getRoot() 111 * @see #getLoader(int,int) 112 */ getLoader(String name)113 public ClassLoader getLoader(String name) { 114 int[] index = denotation.indexFor(name); 115 int level = index[0]; 116 int item = index[1]; 117 return loaders[level][item]; 118 } 119 120 /** 121 * Return the tree's height. 122 * 123 * @see #ClassLoadersBTree(ClassLoader,int) 124 * @see #getLoader(int,int) 125 * @see #getLoader(String) 126 */ getHeight()127 public int getHeight() { 128 return loaders.length; 129 } 130 131 /** 132 * Return the tree's root loader. 133 * 134 * @see #ClassLoadersBTree(ClassLoader,int) 135 * @see #getLoader(int,int) 136 * @see #getLoader(String) 137 */ getRoot()138 public ClassLoader getRoot() { 139 return loaders[0][0]; 140 } 141 } 142