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/*
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* Copyright (c) 2005, 2006, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Oracle designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Oracle in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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package javax.script;
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import java.util.*;
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import java.net.URL;
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import java.io.*;
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import java.security.*;
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import sun.misc.Service;
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import sun.misc.ServiceConfigurationError;
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import sun.reflect.Reflection;
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import sun.security.util.SecurityConstants;
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/**
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* The <code>ScriptEngineManager</code> implements a discovery and instantiation
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* mechanism for <code>ScriptEngine</code> classes and also maintains a
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* collection of key/value pairs storing state shared by all engines created
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* by the Manager. This class uses the <a href="../../../technotes/guides/jar/jar.html#Service%20Provider">service provider</a> mechanism to enumerate all the
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* implementations of <code>ScriptEngineFactory</code>. <br><br>
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* The <code>ScriptEngineManager</code> provides a method to return an array of all these factories
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* as well as utility methods which look up factories on the basis of language name, file extension
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* and mime type.
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* <p>
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* The <code>Bindings</code> of key/value pairs, referred to as the "Global Scope" maintained
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* by the manager is available to all instances of <code>ScriptEngine</code> created
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* by the <code>ScriptEngineManager</code>. The values in the <code>Bindings</code> are
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* generally exposed in all scripts.
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*
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* @author Mike Grogan
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* @author A. Sundararajan
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* @since 1.6
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*/
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public class ScriptEngineManager {
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private static final boolean DEBUG = false;
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/**
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* If the thread context ClassLoader can be accessed by the caller,
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* then the effect of calling this constructor is the same as calling
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* <code>ScriptEngineManager(Thread.currentThread().getContextClassLoader())</code>.
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* Otherwise, the effect is the same as calling <code>ScriptEngineManager(null)</code>.
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*
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* @see java.lang.Thread#getContextClassLoader
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*/
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public ScriptEngineManager() {
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ClassLoader ctxtLoader = Thread.currentThread().getContextClassLoader();
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if (canCallerAccessLoader(ctxtLoader)) {
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if (DEBUG) System.out.println("using " + ctxtLoader);
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init(ctxtLoader);
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} else {
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if (DEBUG) System.out.println("using bootstrap loader");
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init(null);
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}
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}
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/**
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* This constructor loads the implementations of
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* <code>ScriptEngineFactory</code> visible to the given
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* <code>ClassLoader</code> using the <a href="../../../technotes/guides/jar/jar.html#Service%20Provider">service provider</a> mechanism.<br><br>
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* If loader is <code>null</code>, the script engine factories that are
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* bundled with the platform and that are in the usual extension
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* directories (installed extensions) are loaded. <br><br>
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*
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* @param loader ClassLoader used to discover script engine factories.
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*/
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public ScriptEngineManager(ClassLoader loader) {
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init(loader);
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}
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private void init(final ClassLoader loader) {
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globalScope = new SimpleBindings();
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engineSpis = new HashSet<ScriptEngineFactory>();
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nameAssociations = new HashMap<String, ScriptEngineFactory>();
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extensionAssociations = new HashMap<String, ScriptEngineFactory>();
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mimeTypeAssociations = new HashMap<String, ScriptEngineFactory>();
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AccessController.doPrivileged(new PrivilegedAction<Object>() {
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public Object run() {
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initEngines(loader);
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return null;
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}
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});
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}
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private void initEngines(final ClassLoader loader) {
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Iterator itr = null;
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try {
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if (loader != null) {
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itr = Service.providers(ScriptEngineFactory.class, loader);
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} else {
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itr = Service.installedProviders(ScriptEngineFactory.class);
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}
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} catch (ServiceConfigurationError err) {
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System.err.println("Can't find ScriptEngineFactory providers: " +
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err.getMessage());
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if (DEBUG) {
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err.printStackTrace();
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}
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// do not throw any exception here. user may want to
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// manage his/her own factories using this manager
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// by explicit registratation (by registerXXX) methods.
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return;
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}
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try {
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while (itr.hasNext()) {
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try {
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ScriptEngineFactory fact = (ScriptEngineFactory) itr.next();
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engineSpis.add(fact);
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} catch (ServiceConfigurationError err) {
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System.err.println("ScriptEngineManager providers.next(): "
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+ err.getMessage());
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if (DEBUG) {
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err.printStackTrace();
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}
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// one factory failed, but check other factories...
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continue;
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}
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}
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} catch (ServiceConfigurationError err) {
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System.err.println("ScriptEngineManager providers.hasNext(): "
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+ err.getMessage());
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if (DEBUG) {
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err.printStackTrace();
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}
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// do not throw any exception here. user may want to
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// manage his/her own factories using this manager
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// by explicit registratation (by registerXXX) methods.
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return;
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}
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}
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/**
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* <code>setBindings</code> stores the specified <code>Bindings</code>
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* in the <code>globalScope</code> field. ScriptEngineManager sets this
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* <code>Bindings</code> as global bindings for <code>ScriptEngine</code>
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* objects created by it.
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*
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* @param bindings The specified <code>Bindings</code>
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* @throws IllegalArgumentException if bindings is null.
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*/
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public void setBindings(Bindings bindings) {
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if (bindings == null) {
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throw new IllegalArgumentException("Global scope cannot be null.");
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}
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globalScope = bindings;
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}
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/**
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* <code>getBindings</code> returns the value of the <code>globalScope</code> field.
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* ScriptEngineManager sets this <code>Bindings</code> as global bindings for
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* <code>ScriptEngine</code> objects created by it.
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*
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* @return The globalScope field.
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*/
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public Bindings getBindings() {
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return globalScope;
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}
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/**
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* Sets the specified key/value pair in the Global Scope.
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* @param key Key to set
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* @param value Value to set.
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* @throws NullPointerException if key is null.
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* @throws IllegalArgumentException if key is empty string.
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*/
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public void put(String key, Object value) {
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globalScope.put(key, value);
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}
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/**
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* Gets the value for the specified key in the Global Scope
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* @param key The key whose value is to be returned.
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* @return The value for the specified key.
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*/
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public Object get(String key) {
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return globalScope.get(key);
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}
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/**
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* Looks up and creates a <code>ScriptEngine</code> for a given name.
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* The algorithm first searches for a <code>ScriptEngineFactory</code> that has been
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* registered as a handler for the specified name using the <code>registerEngineName</code>
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* method.
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* <br><br> If one is not found, it searches the array of <code>ScriptEngineFactory</code> instances
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* stored by the constructor for one with the specified name. If a <code>ScriptEngineFactory</code>
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* is found by either method, it is used to create instance of <code>ScriptEngine</code>.
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* @param shortName The short name of the <code>ScriptEngine</code> implementation.
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* returned by the <code>getNames</code> method of its <code>ScriptEngineFactory</code>.
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* @return A <code>ScriptEngine</code> created by the factory located in the search. Returns null
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* if no such factory was found. The <code>ScriptEngineManager</code> sets its own <code>globalScope</code>
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* <code>Bindings</code> as the <code>GLOBAL_SCOPE</code> <code>Bindings</code> of the newly
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* created <code>ScriptEngine</code>.
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* @throws NullPointerException if shortName is null.
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*/
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public ScriptEngine getEngineByName(String shortName) {
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if (shortName == null) throw new NullPointerException();
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//look for registered name first
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Object obj;
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if (null != (obj = nameAssociations.get(shortName))) {
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ScriptEngineFactory spi = (ScriptEngineFactory)obj;
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try {
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ScriptEngine engine = spi.getScriptEngine();
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engine.setBindings(getBindings(), ScriptContext.GLOBAL_SCOPE);
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return engine;
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} catch (Exception exp) {
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if (DEBUG) exp.printStackTrace();
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}
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}
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for (ScriptEngineFactory spi : engineSpis) {
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List<String> names = null;
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try {
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names = spi.getNames();
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} catch (Exception exp) {
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if (DEBUG) exp.printStackTrace();
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}
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if (names != null) {
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for (String name : names) {
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if (shortName.equals(name)) {
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try {
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ScriptEngine engine = spi.getScriptEngine();
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engine.setBindings(getBindings(), ScriptContext.GLOBAL_SCOPE);
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return engine;
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} catch (Exception exp) {
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if (DEBUG) exp.printStackTrace();
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}
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}
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}
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}
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}
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return null;
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}
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/**
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* Look up and create a <code>ScriptEngine</code> for a given extension. The algorithm
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* used by <code>getEngineByName</code> is used except that the search starts
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* by looking for a <code>ScriptEngineFactory</code> registered to handle the
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* given extension using <code>registerEngineExtension</code>.
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* @param extension The given extension
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* @return The engine to handle scripts with this extension. Returns <code>null</code>
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* if not found.
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* @throws NullPointerException if extension is null.
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*/
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public ScriptEngine getEngineByExtension(String extension) {
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if (extension == null) throw new NullPointerException();
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//look for registered extension first
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Object obj;
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if (null != (obj = extensionAssociations.get(extension))) {
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ScriptEngineFactory spi = (ScriptEngineFactory)obj;
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try {
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ScriptEngine engine = spi.getScriptEngine();
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engine.setBindings(getBindings(), ScriptContext.GLOBAL_SCOPE);
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return engine;
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} catch (Exception exp) {
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if (DEBUG) exp.printStackTrace();
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}
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}
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for (ScriptEngineFactory spi : engineSpis) {
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List<String> exts = null;
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try {
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exts = spi.getExtensions();
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} catch (Exception exp) {
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if (DEBUG) exp.printStackTrace();
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}
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if (exts == null) continue;
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for (String ext : exts) {
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if (extension.equals(ext)) {
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try {
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ScriptEngine engine = spi.getScriptEngine();
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engine.setBindings(getBindings(), ScriptContext.GLOBAL_SCOPE);
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return engine;
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} catch (Exception exp) {
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if (DEBUG) exp.printStackTrace();
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}
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}
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}
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}
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return null;
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}
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/**
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* Look up and create a <code>ScriptEngine</code> for a given mime type. The algorithm
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* used by <code>getEngineByName</code> is used except that the search starts
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* by looking for a <code>ScriptEngineFactory</code> registered to handle the
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* given mime type using <code>registerEngineMimeType</code>.
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* @param mimeType The given mime type
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* @return The engine to handle scripts with this mime type. Returns <code>null</code>
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* if not found.
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* @throws NullPointerException if mimeType is null.
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*/
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public ScriptEngine getEngineByMimeType(String mimeType) {
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if (mimeType == null) throw new NullPointerException();
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//look for registered types first
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Object obj;
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if (null != (obj = mimeTypeAssociations.get(mimeType))) {
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ScriptEngineFactory spi = (ScriptEngineFactory)obj;
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try {
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ScriptEngine engine = spi.getScriptEngine();
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engine.setBindings(getBindings(), ScriptContext.GLOBAL_SCOPE);
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return engine;
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} catch (Exception exp) {
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if (DEBUG) exp.printStackTrace();
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}
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}
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for (ScriptEngineFactory spi : engineSpis) {
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List<String> types = null;
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try {
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types = spi.getMimeTypes();
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} catch (Exception exp) {
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if (DEBUG) exp.printStackTrace();
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336 |
}
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337 |
if (types == null) continue;
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338 |
for (String type : types) {
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339 |
if (mimeType.equals(type)) {
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340 |
try {
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ScriptEngine engine = spi.getScriptEngine();
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engine.setBindings(getBindings(), ScriptContext.GLOBAL_SCOPE);
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return engine;
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} catch (Exception exp) {
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if (DEBUG) exp.printStackTrace();
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}
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}
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}
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}
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350 |
return null;
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|
351 |
}
|
|
352 |
|
|
353 |
/**
|
|
354 |
* Returns an array whose elements are instances of all the <code>ScriptEngineFactory</code> classes
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|
355 |
* found by the discovery mechanism.
|
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356 |
* @return List of all discovered <code>ScriptEngineFactory</code>s.
|
|
357 |
*/
|
|
358 |
public List<ScriptEngineFactory> getEngineFactories() {
|
|
359 |
List<ScriptEngineFactory> res = new ArrayList<ScriptEngineFactory>(engineSpis.size());
|
|
360 |
for (ScriptEngineFactory spi : engineSpis) {
|
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res.add(spi);
|
|
362 |
}
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|
363 |
return Collections.unmodifiableList(res);
|
|
364 |
}
|
|
365 |
|
|
366 |
/**
|
|
367 |
* Registers a <code>ScriptEngineFactory</code> to handle a language
|
|
368 |
* name. Overrides any such association found using the Discovery mechanism.
|
|
369 |
* @param name The name to be associated with the <code>ScriptEngineFactory</code>.
|
|
370 |
* @param factory The class to associate with the given name.
|
|
371 |
* @throws NullPointerException if any of the parameters is null.
|
|
372 |
*/
|
|
373 |
public void registerEngineName(String name, ScriptEngineFactory factory) {
|
|
374 |
if (name == null || factory == null) throw new NullPointerException();
|
|
375 |
nameAssociations.put(name, factory);
|
|
376 |
}
|
|
377 |
|
|
378 |
/**
|
|
379 |
* Registers a <code>ScriptEngineFactory</code> to handle a mime type.
|
|
380 |
* Overrides any such association found using the Discovery mechanism.
|
|
381 |
*
|
|
382 |
* @param type The mime type to be associated with the
|
|
383 |
* <code>ScriptEngineFactory</code>.
|
|
384 |
*
|
|
385 |
* @param factory The class to associate with the given mime type.
|
|
386 |
* @throws NullPointerException if any of the parameters is null.
|
|
387 |
*/
|
|
388 |
public void registerEngineMimeType(String type, ScriptEngineFactory factory) {
|
|
389 |
if (type == null || factory == null) throw new NullPointerException();
|
|
390 |
mimeTypeAssociations.put(type, factory);
|
|
391 |
}
|
|
392 |
|
|
393 |
/**
|
|
394 |
* Registers a <code>ScriptEngineFactory</code> to handle an extension.
|
|
395 |
* Overrides any such association found using the Discovery mechanism.
|
|
396 |
*
|
|
397 |
* @param extension The extension type to be associated with the
|
|
398 |
* <code>ScriptEngineFactory</code>.
|
|
399 |
* @param factory The class to associate with the given extension.
|
|
400 |
* @throws NullPointerException if any of the parameters is null.
|
|
401 |
*/
|
|
402 |
public void registerEngineExtension(String extension, ScriptEngineFactory factory) {
|
|
403 |
if (extension == null || factory == null) throw new NullPointerException();
|
|
404 |
extensionAssociations.put(extension, factory);
|
|
405 |
}
|
|
406 |
|
|
407 |
/** Set of script engine factories discovered. */
|
|
408 |
private HashSet<ScriptEngineFactory> engineSpis;
|
|
409 |
|
|
410 |
/** Map of engine name to script engine factory. */
|
|
411 |
private HashMap<String, ScriptEngineFactory> nameAssociations;
|
|
412 |
|
|
413 |
/** Map of script file extension to script engine factory. */
|
|
414 |
private HashMap<String, ScriptEngineFactory> extensionAssociations;
|
|
415 |
|
|
416 |
/** Map of script script MIME type to script engine factory. */
|
|
417 |
private HashMap<String, ScriptEngineFactory> mimeTypeAssociations;
|
|
418 |
|
|
419 |
/** Global bindings associated with script engines created by this manager. */
|
|
420 |
private Bindings globalScope;
|
|
421 |
|
|
422 |
private boolean canCallerAccessLoader(ClassLoader loader) {
|
|
423 |
SecurityManager sm = System.getSecurityManager();
|
|
424 |
if (sm != null) {
|
|
425 |
ClassLoader callerLoader = getCallerClassLoader();
|
|
426 |
if (callerLoader != null) {
|
|
427 |
if (loader != callerLoader || !isAncestor(loader, callerLoader)) {
|
|
428 |
try {
|
|
429 |
sm.checkPermission(SecurityConstants.GET_CLASSLOADER_PERMISSION);
|
|
430 |
} catch (SecurityException exp) {
|
|
431 |
if (DEBUG) exp.printStackTrace();
|
|
432 |
return false;
|
|
433 |
}
|
|
434 |
} // else fallthru..
|
|
435 |
} // else fallthru..
|
|
436 |
} // else fallthru..
|
|
437 |
|
|
438 |
return true;
|
|
439 |
}
|
|
440 |
|
|
441 |
// Note that this code is same as ClassLoader.getCallerClassLoader().
|
|
442 |
// But, that method is package private and hence we can't call here.
|
|
443 |
private ClassLoader getCallerClassLoader() {
|
|
444 |
Class caller = Reflection.getCallerClass(3);
|
|
445 |
if (caller == null) {
|
|
446 |
return null;
|
|
447 |
}
|
|
448 |
return caller.getClassLoader();
|
|
449 |
}
|
|
450 |
|
|
451 |
// is cl1 ancestor of cl2?
|
|
452 |
private boolean isAncestor(ClassLoader cl1, ClassLoader cl2) {
|
|
453 |
do {
|
|
454 |
cl2 = cl2.getParent();
|
|
455 |
if (cl1 == cl2) return true;
|
|
456 |
} while (cl2 != null);
|
|
457 |
return false;
|
|
458 |
}
|
|
459 |
}
|