content: /*******************************************************************************
   * Copyright (c) 2000, 2008 IBM Corporation and others.
   * All rights reserved. This program and the accompanying materials
   * are made available under the terms of the Eclipse Public License v1.0
   * which accompanies this distribution, and is available at
   * http://www.eclipse.org/legal/epl-v10.html
   *
   * Contributors:
   *     IBM Corporation - initial API and implementation
   *******************************************************************************/
  package org.eclipse.wst.jsdt.internal.corext.refactoring.reorg;
  
  import java.io.ByteArrayInputStream;
  import java.io.ByteArrayOutputStream;
  import java.io.DataInputStream;
  import java.io.DataOutputStream;
  import java.io.IOException;
  
  import org.eclipse.swt.dnd.ByteArrayTransfer;
  import org.eclipse.swt.dnd.TransferData;
  import org.eclipse.wst.jsdt.core.IJavaScriptElement;
  import org.eclipse.wst.jsdt.core.JavaScriptCore;
  
  public class JavaElementTransfer extends ByteArrayTransfer {
  
  	/**
  	 * Singleton instance.
  	 */
  	private static final JavaElementTransfer fInstance= new JavaElementTransfer();
  
  	// Create a unique ID to make sure that different Eclipse
  	// applications use different "types" of <code>JavaElementTransfer</code>
  	private static final String TYPE_NAME= "java-element-transfer-format:" + System.currentTimeMillis() + ":" + fInstance.hashCode(); //$NON-NLS-2$//$NON-NLS-1$
  
  	private static final int TYPEID= registerType(TYPE_NAME);
  
  	private JavaElementTransfer() {
  	}
  
  	/**
  	 * Returns the singleton instance.
  	 *
  	 * @return the singleton instance
  	 */
  	public static JavaElementTransfer getInstance() {
  		return fInstance;
  	}
  
  	/* (non-Javadoc)
  	 * Method declared on Transfer.
  	 */
  	protected int[] getTypeIds() {
  		return new int[] { TYPEID };
  	}
  	/* (non-Javadoc)
  	 * Returns the type names.
  	 *
  	 * @return the list of type names
  	 */
  	protected String[] getTypeNames() {
  		return new String[] { TYPE_NAME };
  	}
  
  	/* (non-Javadoc)
  	 * @see org.eclipse.swt.dnd.Transfer#javaToNative(java.lang.Object, org.eclipse.swt.dnd.TransferData)
  	 */
  	protected void javaToNative(Object data, TransferData transferData) {
  		if (!(data instanceof IJavaScriptElement[]))
  			return;
  
  		IJavaScriptElement[] javaElements= (IJavaScriptElement[]) data;
  		/*
  		 * The element serialization format is:
  		 *  (int) number of element
  		 * Then, the following for each element:
  		 *  (String) handle identifier
  		 */
  
  		try {
  			ByteArrayOutputStream out= new ByteArrayOutputStream();
  			DataOutputStream dataOut= new DataOutputStream(out);
  
  			//write the number of elements
  			dataOut.writeInt(javaElements.length);
  
  			//write each element
  			for (int i= 0; i < javaElements.length; i++) {
  				writeJavaElement(dataOut, javaElements[i]);
  			}
  
  			//cleanup
  			dataOut.close();
  			out.close();
  			byte[] bytes= out.toByteArray();
  			super.javaToNative(bytes, transferData);
  		} catch (IOException e) {
  			//it's best to send nothing if there were problems
  		}
  	}
  
  	/* (non-Javadoc)
  	 * @see org.eclipse.swt.dnd.Transfer#nativeToJava(org.eclipse.swt.dnd.TransferData)
  	 */
  	protected Object nativeToJava(TransferData transferData) {
  		/*
  		 * The element serialization format is:
  		 *  (int) number of element
  		 * Then, the following for each element:
  		 *  (String) handle identifier
  		 */
  
  		byte[] bytes= (byte[]) super.nativeToJava(transferData);
  		if (bytes == null)
  			return null;
  		DataInputStream in= new DataInputStream(new ByteArrayInputStream(bytes));
  		try {
  			int count= in.readInt();
  			IJavaScriptElement[] results= new IJavaScriptElement[count];
  			for (int i= 0; i < count; i++) {
  				results[i]= readJavaElement(in);
  			}
  			return results;
  		} catch (IOException e) {
  			return null;
  		}
  	}
  
  	private IJavaScriptElement readJavaElement(DataInputStream dataIn) throws IOException {
  		String handleIdentifier= dataIn.readUTF();
  		return JavaScriptCore.create(handleIdentifier);
  	}
  
  	private static void writeJavaElement(DataOutputStream dataOut, IJavaScriptElement element) throws IOException {
  		dataOut.writeUTF(element.getHandleIdentifier());
  	}
  }
  