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/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 * 
 * Copyright 1997-2007 Sun Microsystems, Inc. All rights reserved.
 * 
 * The contents of this file are subject to the terms of either the GNU
 * General Public License Version 2 only ("GPL") or the Common Development
 * and Distribution License("CDDL") (collectively, the "License").  You
 * may not use this file except in compliance with the License. You can obtain
 * a copy of the License at https://glassfish.dev.java.net/public/CDDL+GPL.html
 * or glassfish/bootstrap/legal/LICENSE.txt.  See the License for the specific
 * language governing permissions and limitations under the License.
 * 
 * When distributing the software, include this License Header Notice in each
 * file and include the License file at glassfish/bootstrap/legal/LICENSE.txt.
 * Sun designates this particular file as subject to the "Classpath" exception
 * as provided by Sun in the GPL Version 2 section of the License file that
 * accompanied this code.  If applicable, add the following below the License
 * Header, with the fields enclosed by brackets [] replaced by your own
 * identifying information: "Portions Copyrighted [year]
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 * If you wish your version of this file to be governed by only the CDDL or
 * only the GPL Version 2, indicate your decision by adding "[Contributor]
 * elects to include this software in this distribution under the [CDDL or GPL
 * Version 2] license."  If you don't indicate a single choice of license, a
 * recipient has the option to distribute your version of this file under
 * either the CDDL, the GPL Version 2 or to extend the choice of license to
 * its licensees as provided above.  However, if you add GPL Version 2 code
 * and therefore, elected the GPL Version 2 license, then the option applies
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 */

package com.sun.tools.xjc;

import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLClassLoader;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

import javax.xml.bind.JAXBContext;

import com.sun.istack.tools.MaskingClassLoader;
import com.sun.istack.tools.ParallelWorldClassLoader;

/**
 * Creates a class loader configured to run XJC 1.0/2.0 safely without
 * interference with JAXB 2.0 API in Mustang.
 *
 * @author Kohsuke Kawaguchi
 */
class ClassLoaderBuilder {

    /**
     * Creates a new class loader that eventually delegates to the given {@link ClassLoader}
     * such that XJC can be loaded by using this classloader.
     *
     * @param v
     *      Either "1.0" or "2.0", indicating the version of the -source value.
     */
    protected static ClassLoader createProtectiveClassLoader(ClassLoader cl, String v) throws ClassNotFoundException, MalformedURLException {
        if(noHack)  return cl;  // provide an escape hatch

        boolean mustang = false;

        if(JAXBContext.class.getClassLoader()==null) {
            // JAXB API is loaded from the bootstrap. We need to override one with ours
            mustang = true;

            List mask = new ArrayList(Arrays.asList(maskedPackages));
            mask.add("javax.xml.bind.");

            cl = new MaskingClassLoader(cl,mask);

            URL apiUrl = cl.getResource("javax/xml/bind/annotation/XmlSeeAlso.class");
            if(apiUrl==null)
                throw new ClassNotFoundException("There's no JAXB 2.1 API in the classpath");

            cl = new URLClassLoader(new URL[]{ParallelWorldClassLoader.toJarUrl(apiUrl)},cl);
        }

        //Leave XJC2 in the publicly visible place
        // and then isolate XJC1 in a child class loader,
        // then use a MaskingClassLoader
        // so that the XJC2 classes in the parent class loader
        //  won't interfere with loading XJC1 classes in a child class loader

        if (v.equals("1.0")) {
            if(!mustang)
                // if we haven't used Masking ClassLoader, do so now.
                cl = new MaskingClassLoader(cl,toolPackages);
            cl = new ParallelWorldClassLoader(cl,"1.0/");
        } else {
            if(mustang)
                // the whole RI needs to be loaded in a separate class loader
                cl = new ParallelWorldClassLoader(cl,"");
        }

        return cl;
    }


    /**
     * The list of package prefixes we want the
     * {@link MaskingClassLoader} to prevent the parent
     * classLoader from loading
     */
    private static String[] maskedPackages = new String[]{
        // toolPackages + alpha
        "com.sun.tools.",
        "com.sun.codemodel.",
        "com.sun.relaxng.",
        "com.sun.xml.xsom.",
        "com.sun.xml.bind.",
    };

    private static String[] toolPackages = new String[]{
        "com.sun.tools.",
        "com.sun.codemodel.",
        "com.sun.relaxng.",
        "com.sun.xml.xsom."
    };

    /**
     * Escape hatch in case this class loader hack breaks.
     */
    public static final boolean noHack = Boolean.getBoolean(XJCFacade.class.getName()+".nohack");
}