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/*
* Copyright (c) 2002, 2018, 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.
*
* 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 nsk.share.sysdict;
import nsk.share.*;
/**
* A binary tree of class loaders.
*
* @see TreeNodesDenotation
*/
public class ClassLoadersBTree {
/**
* Cannot instantiate while a tree root and height
* are not specified.
*
* @see #ClassLoadersBTree(ClassLoader,int)
*/
protected ClassLoadersBTree() {
}
/**
* Given the <tt>root</tt> loader, instantiate a binary tree
* of loaders up to the given tree <tt>height</tt>.
*
* @see #getHeight()
* @see #getRoot()
* @see #getLoader(String)
* @see #getLoader(int,int)
*/
public ClassLoadersBTree(ClassLoader root, int height) {
if (height < 1)
throw new IllegalArgumentException("wrong height: " + height);
loaders = new ClassLoader [ height ] [];
for (int level=0; level<height; level++)
loaders[level] = new ClassLoader [1 << level];
loaders[0][0] = root;
generateSubtree("");
}
private void generateSubtree(String name) {
int level = name.length();
int height = loaders.length;
if (level+1 == height)
return;
String nameL = name + "L";
String nameR = name + "R";
int[] index = denotation.indexFor(name);
int[] indexL = denotation.indexFor(nameL);
int[] indexR = denotation.indexFor(nameR);
// assertion: index[0] == level
// assertion: indexL[0] == indexR[0] == level+1
int item = index[1];
int itemL = indexL[1];
int itemR = indexR[1];
ClassLoader parent = loaders[level][item];
ClassLoader childL = new DummyClassLoader(parent);
ClassLoader childR = new DummyClassLoader(parent); // another item
loaders[level+1][itemL] = childL;
loaders[level+1][itemR] = childR;
generateSubtree(nameL);
generateSubtree(nameR);
}
private ClassLoader loaders[][]; // loaders[0][0] is root
private Denotation denotation = new TreeNodesDenotation();
/**
* Return the loader found at the given <tt>level</tt> of
* this loaders tree, and having the given <tt>item</tt>
* number at the enumeration of that <tt>level</tt>.
*
* <p>The value of <tt>level</tt> must be from <tt>0</tt>
* to <tt>getHeight()-1</tt>, and the <tt>item</tt> number
* must be from <tt>0</tt> to <tt>2<sup>level</sup>-1</tt>.
*
* @see #getHeight()
* @see #getRoot()
* @see #getLoader(String)
*/
public ClassLoader getLoader(int level, int item) {
return loaders[level][item];
}
/**
* Return the loader having the giving <tt>name</tt> at
* the standard denotation of binary tree nodes.
*
* @see #getHeight()
* @see #getRoot()
* @see #getLoader(int,int)
*/
public ClassLoader getLoader(String name) {
int[] index = denotation.indexFor(name);
int level = index[0];
int item = index[1];
return loaders[level][item];
}
/**
* Return the tree's height.
*
* @see #ClassLoadersBTree(ClassLoader,int)
* @see #getLoader(int,int)
* @see #getLoader(String)
*/
public int getHeight() {
return loaders.length;
}
/**
* Return the tree's root loader.
*
* @see #ClassLoadersBTree(ClassLoader,int)
* @see #getLoader(int,int)
* @see #getLoader(String)
*/
public ClassLoader getRoot() {
return loaders[0][0];
}
}
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