package lab.art;

/**
 * This class represents the variable x expression.
 * 
 * @author Franck van Breugel
 */
public class VariableX extends Expression 
{
    /**
     * Initializes this variable x expression.
     */
    public VariableX() 
    {
	super();
    }
    
    /**
     * Evaluates this variable x expression at the given x- and y-coordinate.
     * 
     * @param x the x-coordinate.
     * @pre. x >= -1 && x <= 1
     * @param y the y-coordinate.
     * @pre. y >= -1 && y <= 1
     * @return the value of this variable x expression at the given x- and y-coordinate.
     */
    public double evaluate(double x, double y)
    {
	return x;
    }
    
    /**
     * Returns a string representation of this variable x expression.
     * The string consists of "x".
     * 
     * @return string representation of this variable x expression.
     */
    public String toString()
    {
	return "x";
    }
}