TightSourceRangeComputer.java

/*******************************************************************************
 * Copyright (c) 2005, 2011 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.jdt.internal.corext.refactoring.util;

import java.util.HashSet;
import java.util.Iterator;
import java.util.List;

import org.eclipse.jdt.core.dom.ASTNode;
import org.eclipse.jdt.core.dom.StructuralPropertyDescriptor;
import org.eclipse.jdt.core.dom.rewrite.TargetSourceRangeComputer;

/**
 * A source range computer that uses the shortest possible source range for a given set of nodes.
 * <p>
 * For other nodes, the default extended source range from
 * {@link TargetSourceRangeComputer#computeSourceRange(ASTNode)} is used.
 * <p>
 * For nodes inside "tight" nodes, the source range is the extended source range, unless this would
 * violate the no-overlapping condition from the superclass.
 * 
 * @since 3.2
 */
public class TightSourceRangeComputer extends TargetSourceRangeComputer {
	private HashSet<ASTNode> fTightSourceRangeNodes= new HashSet<ASTNode>();

	/**
	 * Add the given node to the set of "tight" nodes.
	 * 
	 * @param reference a node
	 * @since 3.2
	 */
	public void addTightSourceNode(ASTNode reference) {
		fTightSourceRangeNodes.add(reference);

	    List<StructuralPropertyDescriptor> properties= reference.structuralPropertiesForType();
	    for (Iterator<StructuralPropertyDescriptor> iterator= properties.iterator(); iterator.hasNext();) {
	        StructuralPropertyDescriptor descriptor= iterator.next();
	        if (descriptor.isChildProperty()) {
	        	ASTNode child= (ASTNode)reference.getStructuralProperty(descriptor);
	        	if (child != null && isExtending(child, reference)) {
	        		addTightSourceNode(child);
	        	}
	        } else if (descriptor.isChildListProperty()) {
	        	List<? extends ASTNode> children= (List<? extends ASTNode>) reference.getStructuralProperty(descriptor);
	        	for (Iterator<? extends ASTNode> iterator2= children.iterator(); iterator2.hasNext();) {
	                ASTNode child= iterator2.next();
	                if (isExtending(child, reference)) {
		        		addTightSourceNode(child);
		        	}
                }
	        }
        }
    }

	@Override
	public SourceRange computeSourceRange(ASTNode node) {
		if (fTightSourceRangeNodes.contains(node)) {
			return new TargetSourceRangeComputer.SourceRange(node.getStartPosition(), node.getLength());
		} else {
			return super.computeSourceRange(node); // see bug 85850
		}
	}

	private boolean isExtending(ASTNode child, ASTNode parent) {
	    SourceRange extendedRange= super.computeSourceRange(child);

	    int parentStart= parent.getStartPosition();
		int extendedStart= extendedRange.getStartPosition();
		if (parentStart > extendedStart)
			return true;

		int parentEnd= parentStart + parent.getLength();
		int extendedEnd= extendedStart + extendedRange.getLength();
		if (parentEnd < extendedEnd)
			return true;

	    return false;
    }
}