ltk/org.eclipse.statet.ltk.core/src/org/eclipse/statet/ltk/model/core/util/ElementComparator.java

/*=============================================================================#
 # Copyright (c) 2013, 2020 Stephan Wahlbrink and others.
 # 
 # This program and the accompanying materials are made available under the
 # terms of the Eclipse Public License 2.0 which is available at
 # https://www.eclipse.org/legal/epl-2.0, or the Apache License, Version 2.0
 # which is available at https://www.apache.org/licenses/LICENSE-2.0.
 # 
 # SPDX-License-Identifier: EPL-2.0 OR Apache-2.0
 # 
 # Contributors:
 #     Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation
 #=============================================================================*/

package org.eclipse.statet.ltk.model.core.util;

import java.util.Comparator;

import com.ibm.icu.text.Collator;

import org.eclipse.statet.ltk.core.LTKUtils;
import org.eclipse.statet.ltk.model.core.elements.IModelElement;
import org.eclipse.statet.ltk.model.core.elements.ISourceElement;
import org.eclipse.statet.ltk.model.core.elements.ISourceUnit;


public class ElementComparator implements Comparator<IModelElement> {
	
	
	private final Collator unitComparator;
	private final Collator elementComparator;
	
	
	public ElementComparator() {
		this(Collator.getInstance());
	}
	
	public ElementComparator(final Collator elementComparator) {
		this.unitComparator= Collator.getInstance();
		this.elementComparator= elementComparator;
	}
	
	
	@Override
	public int compare(final IModelElement e1, final IModelElement e2) {
		final ISourceUnit u1= LTKUtils.getSourceUnit(e1);
		final ISourceUnit u2= LTKUtils.getSourceUnit(e2);
		int result= 0;
		if (u1 != null && u2 != null) {
			if (u1 != u2) {
				result= this.unitComparator.compare(u1.getId(), u2.getId());
			}
			if (result != 0) {
				return result;
			}
			if (e1 instanceof ISourceElement) {
				if (e2 instanceof ISourceElement) {
					return compareSourceElementsInUnit((ISourceElement) e1, (ISourceElement) e2);
				}
				return -1000000;
			}
			else if (e2 instanceof ISourceElement) { // && !(e1 instanceof ISourceUnit)
				return 1000000;
			}
			else {
				return this.elementComparator.compare(e1.getId(), e2.getId());
			}
		}
		if (u1 == null && u2 != null) {
			return Integer.MAX_VALUE;
		}
		if (u2 == null && u1 != null) {
			return Integer.MIN_VALUE;
		}
		return 0;
	}
	
	protected int compareSourceElementsInUnit(final ISourceElement e1, final ISourceElement e2) {
		return e1.getSourceRange().getStartOffset() - e2.getSourceRange().getStartOffset();
	}
	
}