/**

  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.

  *

  * Copyright 2013-2014 Oracle and/or its affiliates. All rights reserved.

  *

  * Oracle and Java are registered trademarks of Oracle and/or its affiliates.

  * Other names may be trademarks of their respective owners.

  *

  * 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

  * http://www.netbeans.org/cddl-gplv2.html

  * or nbbuild/licenses/CDDL-GPL-2-CP. 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

  * nbbuild/licenses/CDDL-GPL-2-CP.  Oracle designates this

  * particular file as subject to the "Classpath" exception as provided

  * by Oracle 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] [name of copyright owner]"

  *

  * Contributor(s):

  *

  * The Original Software is NetBeans. The Initial Developer of the Original

  * Software is Oracle. Portions Copyright 2013-2014 Oracle. All Rights Reserved.

  *

  * 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 do not 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

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 package org.netbeans.html.boot.impl;

 import java.io.Closeable;

 import java.io.Flushable;

 import java.io.IOException;

 import java.util.logging.Level;

 import java.util.logging.Logger;

 import org.netbeans.html.boot.spi.Fn;

 import org.objectweb.asm.Opcodes;

 /**

  *

  * @author Jaroslav Tulach

  */

 public final class FnContext implements Closeable {

     private static final Logger LOG = Logger.getLogger(FnContext.class.getName());

     private static final FnContext DUMMY;

     static {

         DUMMY = new FnContext(null, null);

         DUMMY.prev = DUMMY;

     }

     public static boolean isJavaScriptCapable(ClassLoader l) {

         if (l instanceof JsClassLoader) {

             return true;

         }

         if (l.getResource("META-INF/net.java.html.js.classes") != null) {

             return false;

         }

         return true;

     }

     public static boolean isAsmPresent() {

         Throwable t;

         try {

             Class.forName(Opcodes.class.getName());

             return true;

         } catch (LinkageError ex) {

             t = ex;

         } catch (ClassNotFoundException ex) {

             t = ex;

         }

         LOG.log(Level.SEVERE, "When using @JavaScriptBody methods, one needs to either:");

         LOG.log(Level.SEVERE, " - include asm-5.0.jar on runtime classpath");

         LOG.log(Level.SEVERE, " - post process classes, see http://bits.netbeans.org/html+java/dev/net/java/html/js/package-summary.html#post-process");

         LOG.log(Level.SEVERE, "Cannot initialize asm-5.0.jar!", t);

         return false;

     }

     private Object prev;

     private final Fn.Presenter current;

     private FnContext(Fn.Presenter prevP, Fn.Presenter newP) {

         this.current = newP;

         this.prev = prevP;

     }

     @Override

     public void close() throws IOException {

         if (prev != this) {

             currentPresenter((Fn.Presenter)prev);

             prev = this;

             if (current instanceof Flushable) {

                 ((Flushable)current).flush();

             }

         }

     }

 /*

     @Override

     protected void finalize() throws Throwable {

         if (prev != null) {

             LOG.warning("Unclosed context!");

         }

     }

 */

     public static Closeable activate(Fn.Presenter newP) {

         final Fn.Presenter oldP = currentPresenter(newP);

         if (oldP == newP) {

             return DUMMY;

         }

         return new FnContext(oldP, newP);

     }

     private static final ThreadLocal<Fn.Presenter> CURRENT = new ThreadLocal<Fn.Presenter>();

     public static Fn.Presenter currentPresenter(Fn.Presenter p) {

         Fn.Presenter prev = CURRENT.get();

         CURRENT.set(p);

         return prev;

     }

     public static Fn.Presenter currentPresenter(boolean fail) {

         Fn.Presenter p = CURRENT.get();

         if (p == null && fail) {

             throw new IllegalStateException("No current WebView context around!");

         }

         return p;

     }

 }