org.eclipse.equinox.p2.cudf/src/main/java/org/eclipse/equinox/p2/cudf/solver/ParanoidOptimizationFunction.java

/*******************************************************************************
 * Copyright (c) 2009 Daniel Le Berre 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: Daniel Le Berre - initial API and implementation
 ******************************************************************************/
package org.eclipse.equinox.p2.cudf.solver;

import java.math.BigInteger;
import java.util.ArrayList;
import java.util.List;
import org.eclipse.equinox.p2.cudf.metadata.InstallableUnit;

//	PARANOID: we want to answer the user request, minimizing the number
//    of packages removed in the solution, and also the packages
//    changed by the solution; the optimization criterion is
//
//         lex( min #removed, min #changed)
//
//    Hence, two solutions S1 and S2 will be compared as follows:
//
//    i) compute ri = #removed(U,Si), ci = #changed(U,Si)
//
//    ii) S1 is better than S2 iff r1 < r2 or (r1=r2 and c1<c2)
public class ParanoidOptimizationFunction extends OptimizationFunction {

	public List createOptimizationFunction(InstallableUnit metaIu) {
		List weightedObjects = new ArrayList();
		BigInteger weight = BigInteger.valueOf(slice.size() + 1);
		removed(weightedObjects, weight, metaIu);
		changed(weightedObjects, BigInteger.ONE, metaIu);
		if (!weightedObjects.isEmpty()) {
			return weightedObjects;
		}
		return null;
	}

	public String getName() {
		return "misc 2010 paranoid";
	}

	public void printSolutionValue() {
		int removed = 0, changed = 0;
		List proof = new ArrayList();
		for (int i = 0; i < removalVariables.size(); i++) {
			Object var = removalVariables.get(i);
			if (dependencyHelper.getBooleanValueFor(var)) {
				removed++;
				proof.add(var);
			}
		}
		for (int i = 0; i < changeVariables.size(); i++) {
			Object var = changeVariables.get(i);
			if (dependencyHelper.getBooleanValueFor(var)) {
				changed++;
				proof.add(var);
			}
		}
		System.out.println("# Paranoid criteria value: -" + removed + ", -" + changed);
		System.out.println("# Proof: " + proof);
	}
}