BufferChangedEvent.java

/*******************************************************************************
 * Copyright (c) 2000, 2004 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials 
 * are made available under the terms of the Common Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/cpl-v10.html
 * 
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.rubypeople.rdt.core;

import java.util.EventObject;

/**
 * A buffer changed event describes how a buffer has changed. These events are
 * used in <code>IBufferChangedListener</code> notifications.
 * <p>
 * For text insertions, <code>getOffset</code> is the offset of the first
 * inserted character, <code>getText</code> is the inserted text, and
 * <code>getLength</code> is 0.
 * </p>
 * <p>
 * For text removals, <code>getOffset</code> is the offset of the first
 * removed character, <code>getText</code> is <code>null</code>, and
 * <code>getLength</code> is the length of the text that was removed.
 * </p>
 * <p>
 * For replacements (including <code>IBuffer.setContents</code>),
 * <code>getOffset</code> is the offset of the first replaced character,
 * <code>getText</code> is the replacement text, and <code>getLength</code>
 * is the length of the original text that was replaced.
 * </p>
 * <p>
 * When a buffer is closed, <code>getOffset</code> is 0,
 * <code>getLength</code> is 0, and <code>getText</code> is
 * <code>null</code>.
 * </p>
 * <p>
 * This class is not intended to be instantiated or subclassed by clients.
 * Instances of this class are automatically created by the Java model.
 * </p>
 * 
 * @see IBuffer
 */
public class BufferChangedEvent extends EventObject {

    /**
     * The length of text that has been modified in the buffer.
     */
    private int length;

    /**
     * The offset into the buffer where the modification took place.
     */
    private int offset;

    /**
     * The text that was modified.
     */
    private String text;

    private static final long serialVersionUID = 655379473891745999L; // backward
                                                                        // compatible

    /**
     * Creates a new buffer changed event indicating that the given buffer has
     * changed.
     * 
     * @param buffer
     *            the given buffer
     * @param offset
     *            the given offset
     * @param length
     *            the given length
     * @param text
     *            the given text
     */
    public BufferChangedEvent(IBuffer buffer, int offset, int length, String text) {
        super(buffer);
        this.offset = offset;
        this.length = length;
        this.text = text;
    }

    /**
     * Returns the buffer which has changed.
     * 
     * @return the buffer affected by the change
     */
    public IBuffer getBuffer() {
        return (IBuffer) this.source;
    }

    /**
     * Returns the length of text removed or replaced in the buffer, or 0 if
     * text has been inserted into the buffer.
     * 
     * @return the length of the original text fragment modified by the buffer
     *         change (<code> 0 </code> in case of insertion).
     */
    public int getLength() {
        return this.length;
    }

    /**
     * Returns the index of the first character inserted, removed, or replaced
     * in the buffer.
     * 
     * @return the source offset of the textual manipulation in the buffer
     */
    public int getOffset() {
        return this.offset;
    }

    /**
     * Returns the text that was inserted, the replacement text, or
     * <code>null</code> if text has been removed.
     * 
     * @return the text corresponding to the buffer change (<code> null </code>
     *         in case of deletion).
     */
    public String getText() {
        return this.text;
    }
}