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  * 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

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  * 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

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  * "Portions Copyrighted [year] [name of copyright owner]"

  *

  * Contributor(s):

  *

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

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  * to extend the choice of license to its licensees as provided above.

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 package org.netbeans.html.ko4j;

 import net.java.html.json.Model;

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

 import org.apidesign.html.context.spi.Contexts;

 import org.apidesign.html.json.spi.Technology;

 import org.apidesign.html.json.spi.Transfer;

 import org.apidesign.html.json.spi.WSTransfer;

 import org.openide.util.lookup.ServiceProvider;

 /** Support for <a href="http://knockoutjs.com">knockout.js</a>

  * and its Java binding via {@link Model model classes}.

  * Registers {@link ContextProvider}, so {@link ServiceLoader} can find it.

  *

  * @author Jaroslav Tulach <jtulach@netbeans.org>

  * @since 0.7

  */

 @ServiceProvider(service = Contexts.Provider.class)

 public final class KO4J implements Contexts.Provider {

     private final Fn.Presenter presenter;

     private FXContext c;

     public KO4J() {

         this(null);

     }

     public KO4J(Fn.Presenter presenter) {

         this.presenter = presenter;

     }

     private FXContext getKO() {

         if (c == null) {

             c = new FXContext(presenter == null ? Fn.activePresenter() : presenter);

         }

         return c;

     }

     /** Return instance of the knockout.js for Java technology.

      * @return non-null instance

      */

     public Technology knockout() {

         return getKO();

     }

     /** Browser based implementation of transfer interface. Uses

      * browser method to convert string to JSON.

      * 

      * @return non-null instance

      */

     public Transfer transfer() {

         return getKO();

     }

     /** Returns browser based implementation of websocket transfer.

      * If available (for example JavaFX WebView on JDK7 does not have

      * this implementation).

      * 

      * @return an instance or <code>null</code>, if there is no

      *   <code>WebSocket</code> object in the browser

      */

     public WSTransfer<?> websockets() {

         return getKO().areWebSocketsSupported() ? getKO() : null;

     }

     /** Registers technologies at position 100:

      * <ul>

      *   <li>{@link #knockout()}</li>

      *   <li>{@link #transfer()}</li>

      *   <li>{@link #websockets()()} - if browser supports web sockets</li>

      * </ul>

      * @param context the context to register to

      * @param requestor the class requesting the registration

      */

     @Override

     public void fillContext(Contexts.Builder context, Class<?> requestor) {

         if (FXContext.isJavaScriptEnabled()) {

             context.register(Technology.class, knockout(), 100);

             context.register(Transfer.class, transfer(), 100);

             if (c.areWebSocketsSupported()) {

                 context.register(WSTransfer.class, websockets(), 100);

             }

         }

     }

 }