EDIT

/**

* Copyright (C) 2007 EDIT

* European Distributed Institute of Taxonomy 

* http://www.e-taxonomy.eu

* 

* The contents of this file are subject to the Mozilla Public License Version 1.1

* See LICENSE.TXT at the top of this package for the full license terms.

*/

package eu.etaxonomy.taxeditor.editor.name;

import java.util.ArrayList;

import java.util.Collection;

import java.util.Scanner;

import org.eclipse.swt.custom.StyledText;

import org.eclipse.swt.events.KeyEvent;

import org.eclipse.swt.events.KeyListener;

import org.eclipse.swt.events.VerifyEvent;

import org.eclipse.swt.events.VerifyListener;

/**

 * Checks text entered into a StyledText widget for line breaks, sends

 * split text to abstract method handleSplitText().

 *  <p>

 * VerifyListener interface methods break up the text into lines. Each line is sent individually

 * to the handleSplitText() method when the KeyListener interface method keyReleased() is called.

 * This is because if the StyledText widget is disposed before the key is released, an SWT

 * exception occurs.

 * <p>

 * The listener should be set on the StyledText widget as follows:

 * <code><pre>

 * 		StyledText styledText = new SourceViewer().getTextWidget();

 *		LineBreakListener lineBreakListener = new LineBreakListener() {

 *			public void handleSplitText(String text) {

 *				... some operation ...

 *			}

 *		};

 *

 *		styledText.addVerifyListener(lineBreakListener);

 *		styledText.addKeyListener(lineBreakListener);

 * </pre></code>

 *

 * @author p.ciardelli

 * @created 19.05.2008

 * @version 1.0

 */

public abstract class LineBreakListener implements VerifyListener, KeyListener {

	Collection<String> splitTexts;

	/**

	 * {@inheritDoc}

	 *

	 * Checks for 3 conditions of name viewer text:

	 *   1) no line breaks in text

	 *   2) line break at the end of the text

	 *   3) line break in the middle of the text

	 * @see org.eclipse.swt.events.VerifyListener#verifyText(org.eclipse.swt.events.VerifyEvent)

	 */

	public void verifyText(VerifyEvent e) {

		String verifyText = e.text;

		StyledText styledText = (StyledText) e.widget;

		String widgetText = styledText.getText(); 

		int cursorPosition = styledText.getCaretOffset();

		// If no line break in verifyText, Parse text normally

		if (!verifyText.contains(System.getProperty("line.separator"))) {

			return;

		}

		// Don't add verifyText without further processing

		e.doit = false;

		// Initialize split text collection

		splitTexts = new ArrayList<String>();

		// If user has entered return at the end of the line,

		//  make a new, empty synonym

		if (widgetText.length() == cursorPosition &&

				verifyText.equals(System.getProperty("line.separator"))) {

			splitTexts.add("");

			return;

		}

		// Concatenate old and new texts

		String textForSplitting = widgetText.substring(0, cursorPosition) 

				+ verifyText

				+ widgetText.substring(cursorPosition);

		// Split on line breaks

		Scanner scanner = new Scanner( textForSplitting );

		scanner.useDelimiter (System.getProperty("line.separator"));

		// Put first string into name viewer

		styledText.setText(scanner.next());	

		// Start new synonyms with the rest

		while (scanner.hasNext()) {

			splitTexts.add(scanner.next());

		}

	}

	/** {@inheritDoc} */

	public void keyPressed(KeyEvent e) {}

	/** {@inheritDoc} */

	public void keyReleased(KeyEvent e) {

		if (splitTexts != null) {

			for (String text : splitTexts) {

				handleSplitText(text);

			}

			splitTexts = null;

		}

	}

	/**

	 * <p>handleSplitText</p>

	 *

	 * @param text a {@link java.lang.String} object.

	 */

	abstract public void handleSplitText(String text);

}