org.eclipse.text/src/org/eclipse/text/edits/MultiTextEdit.java

/*******************************************************************************
 * Copyright (c) 2000, 2003 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.eclipse.text.edits;

import org.eclipse.jface.text.Assert;
import org.eclipse.jface.text.BadLocationException;
import org.eclipse.jface.text.IDocument;
import org.eclipse.jface.text.IRegion;

/**
 * A multi-text edit can be used to aggregate several edits into
 * one edit. The edit itself doesn't modify a document.
 * <p>
 * Clients are allowed to implement subclasses of a multi-text 
 * edit.Subclasses must implement <code>doCopy()</code> to ensure
 * the a copy of the right type is created. Not implementing 
 * <code>doCopy()</code> in subclasses will result in an assertion
 * failure during copying. 
 * 
 * @since 3.0
 */
public class MultiTextEdit extends TextEdit {

	private boolean fDefined;

	/**
	 * Creates a new <code>MultiTextEdit</code>. The range
	 * of the edit is determined by the range of its children.
	 * 
	 * Adding this edit to a parent edit sets its range to the
	 * range covered by its children. If the edit doesn't have 
	 * any children its offset is set to the parent's offset 
	 * and its length is set to 0.
	 */
	public MultiTextEdit() {
		super(0, Integer.MAX_VALUE);
		fDefined= false;
	}
	
	/**
	 * Creates a new </code>MultiTextEdit</code> for the given
	 * range. Adding a child to this edit which isn't covered 
	 * by the given range will result in an exception.
	 * 
	 * @param offset the edit's offset
	 * @param length the edit's length.
	 * @see TextEdit#addChild(TextEdit)
	 * @see TextEdit#addChildren(TextEdit[])
	 */
	public MultiTextEdit(int offset, int length) {
		super(offset, length);
		fDefined= true;
	}
	
	/*
	 * Copy constructor.
	 */
	protected MultiTextEdit(MultiTextEdit other) {
		super(other);
	}

	/**
	 * Checks the edit's integrity. 
	 * <p>
	 * Note that this method <b>should only be called</b> by the edit
	 * framework and not by normal clients.</p>
	 *<p>
	 * This default implementation does nothing. Subclasses may override
	 * if needed.</p>
	 * 
	 * @exception MalformedTreeException if the edit isn't in a valid state
	 *  and can therefore not be executed
	 */
	protected void checkIntegrity() throws MalformedTreeException {
		// does nothing
	}

	/*
	 * @see org.eclipse.text.edits.TextEdit#canZeroLengthCover()
	 */
	protected boolean canZeroLengthCover() {
		return true;
	}
	
	/*
	 * @see TextEdit#copy
	 */	
	protected TextEdit doCopy() {
		Assert.isTrue(MultiTextEdit.class == getClass(), "Subclasses must reimplement copy0"); //$NON-NLS-1$
		return new MultiTextEdit(this);
	}

	/*
	 * @see TextEdit#accept0
	 */
	protected void accept0(TextEditVisitor visitor) {
		boolean visitChildren = visitor.visit(this);
		if (visitChildren) {
			acceptChildren(visitor);
		}
	}

	/*
	 * @see TextEdit#performConsistencyCheck
	 */	
	/* package */ void performConsistencyCheck(TextEditProcessor processor, IDocument document) throws MalformedTreeException {
		checkIntegrity();
	}
	
	/*
	 * @see TextEdit#performDocumentUpdating
	 */	
	/* package */ int performDocumentUpdating(IDocument document) throws BadLocationException {
		fDelta= 0;
		return fDelta;
	}
	
	/*
	 * @see TextEdit#deleteChildren
	 */	
	/* package */ boolean deleteChildren() {
		return false;
	}
	
	/* package */ void aboutToBeAdded(TextEdit parent) {
		defineRegion(parent.getOffset());
	}

	/* package */ void defineRegion(int parentOffset) {
		if (fDefined)
			return;
		if (hasChildren()) {
			IRegion region= getCoverage(getChildren());
			internalSetOffset(region.getOffset());
			internalSetLength(region.getLength());
		} else {
			internalSetOffset(parentOffset);
			internalSetLength(0);
		}
		fDefined= true;
	}
}