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Universal interface to decision procedures, constraint solvers, model counters, and related tools
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package za.ac.sun.cs.green.service.slicer;

import java.util.Collections;
import java.util.Set;

import za.ac.sun.cs.green.Green;
import za.ac.sun.cs.green.Instance;
import za.ac.sun.cs.green.expr.Expression;
import za.ac.sun.cs.green.service.BasicService;
import za.ac.sun.cs.green.service.factorizer.FactorExpressionOld;
import za.ac.sun.cs.green.util.Reporter;

public class SATFactorSlicerService extends BasicService {

	/**
	 * Number of times the slicer has been invoked.
	 */
	private int invocationCount = 0;

	/**
	 * Total number of conjuncts processed.
	 */
	private int totalConjunctCount = 0;

	/**
	 * Number of minimal conjuncts returned.
	 */
	private int minimalConjunctCount = 0;

	/**
	 * Total number of variables processed.
	 */
	private int totalVariableCount = 0;

	/**
	 * Number of minimal variables returned.
	 */
	private int minimalVariableCount = 0;

	public SATFactorSlicerService(Green solver) {
		super(solver);
	}

	@Override
	public Set processRequest(Instance instance) {
		@SuppressWarnings("unchecked")
		Set result = (Set) instance.getData(getClass());
		if (result == null) {
			final Instance p = instance.getParent();

			// Handle two initial conditions: no parent and no FactoredConstraint for the
			// parent
			FactorExpressionOld fc0 = null;
			if (p != null) {
				fc0 = (FactorExpressionOld) p.getData(FactorExpressionOld.class);
				if (fc0 == null) {
					// Construct the parent's factor and store it
					fc0 = new FactorExpressionOld(null, p.getFullExpression());
					p.setData(FactorExpressionOld.class, fc0);
				}
			}

			final FactorExpressionOld fc = new FactorExpressionOld(fc0, instance.getExpression());
			instance.setData(FactorExpressionOld.class, fc);

			final Expression e = fc.getDependentFactor(instance.getExpression());

			final Instance i = new Instance(getSolver(), instance.getSource(), null, e);
			result = Collections.singleton(i);
			instance.setData(getClass(), result);

			// First update our statistics
			invocationCount++;
			minimalVariableCount += fc.getDependentVariableCount(instance.getExpression());
			minimalConjunctCount += fc.getDependentConjunctCount(instance.getExpression());
			totalConjunctCount += fc.getConjunctCount();
			totalVariableCount += fc.getVariableCount();
		}
		return result;
	}

	@Override
	public void report(Reporter reporter) {
		reporter.setContext(getClass().getSimpleName());
		reporter.report("invocations", invocationCount);
		reporter.report("totalConjuncts", totalConjunctCount);
		reporter.report("minimalConjuncts", minimalConjunctCount);
		double conjunctReduction = (totalConjunctCount - minimalConjunctCount) * 100.0D / totalConjunctCount;
		reporter.report("conjunctReduction", conjunctReduction);
		reporter.report("totalVariables", totalVariableCount);
		reporter.report("minimalVariables", minimalVariableCount);
		double variableReduction = (totalVariableCount - minimalVariableCount) * 100.0D / totalVariableCount;
		reporter.report("variableReduction", variableReduction);
	}

}