package ac.essex.gp.nodes.logic;

import ac.essex.gp.params.NodeParams;
import ac.essex.gp.params.ChildConstraints;
import ac.essex.gp.params.RangeTypes;
import ac.essex.gp.tree.Terminal;
import ac.essex.gp.tree.Node;
import ac.essex.gp.util.DataStack;

/**
 * <p/>
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version,
 * provided that any use properly credits the author.
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details at http://www.gnu.org
 * </p>
 *
 * @author Olly Oechsle, University of Essex, Date: 13-Mar-2007
 * @version 1.0
 */
public class Equals extends Node {

    public Equals() {
        super(2);
    }

    public int getReturnType() {
        return NodeParams.BOOLEAN;
    }

    public int getChildType(int index) {
        return NodeParams.NUMBER;
    }

    public int getChildConstraint(int index) {
        return index == 0? ChildConstraints.MUST_BE_TERMINAL : ChildConstraints.MUST_BE_ERC;
    }

    public int getChildRangeType(int index) {
        // if we're placing the second child and the first child is a terminal,
        // see what kind of comparison the terminal prefers
        if (index == 1 && child[0] != null && child[0] instanceof Terminal) {
            return ((Terminal) child[0]).getRangeID();
        }
        return RangeTypes.DONT_CARE;
    }

    public double execute(DataStack data) {
        data.value = child[0].execute(data) == child[1].execute(data)? 1 : 0;
        return debugger.record(data.value);
    }

    public String toJava() {
        return child[0].getName() + " == " + child[1].getName();
    }

}