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ECJ, A Java-based Evolutionary Computation Research System. ECJ is a research EC system written in Java. It was designed to be highly flexible, with nearly all classes (and all of their settings) dynamically determined at runtime by a user-provided parameter file. All structures in the system are arranged to be easily modifiable. Even so, the system was designed with an eye toward efficiency. ECJ is developed at George Mason University's ECLab Evolutionary Computation Laboratory. The software has nothing to do with its initials' namesake, Evolutionary Computation Journal. ECJ's sister project is MASON, a multi-agent simulation system which dovetails with ECJ nicely.

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/*
  Copyright 2013 by Sean Luke
  Licensed under the Academic Free License version 3.0
  See the file "LICENSE" for more information
*/

package ec.app.majority.func;
import ec.*;
import ec.app.majority.*;
import ec.gp.*;
import ec.util.*;

public class If extends GPNode
    {
    public String toString() { return "if"; }

    public int expectedChildren() { return 3; }
    
    public void eval(final EvolutionState state,
        final int thread,
        final GPData input,
        final ADFStack stack,
        final GPIndividual individual,
        final Problem problem)
        {
        children[0].eval(state,thread,input,stack,individual,problem);

        MajorityData md = (MajorityData) input;
        long y0 = md.data0;
        long y1 = md.data1;
        
        children[1].eval(state,thread,input,stack,individual,problem);
        long z0 = md.data0;
        long z1 = md.data1;

        children[2].eval(state,thread,input,stack,individual,problem);

        // IF Y THEN Z ELSE MD is
        // (Y -> Z) ^ (~Y -> MD)
        // (!Y v Z) ^ (Y v MD)
        md.data0 = (~y0 | z0) & (y0 | (md.data0));
        md.data1 = (~y1 | z1) & (y1 | (md.data1));
        }
    }