Calculable.java

package de.congrace.exp4j;

/**
 * This is the basic result class of the exp4j {@link ExpressionBuilder}
 * 
 * @author frank asseg
 * 
 */
public interface Calculable {
	/**
	 * calculate the result of the expression
	 * 
	 * @return the result of the calculation
	 */
	public double calculate();

	/**
	 * calculate the result of the expression
	 * 
	 * @param variableValues
	 *            the values of the variable. The values must be in the same order as the declaration of variables in
	 *            the {@link ExpressionBuilder} used to construct this {@link Calculable} instance
	 * @return the result of the calculation
	 */
	public double calculate(double... variableValues);
	
	/**
	 * return the expression in reverse polish postfix notation
	 * 
	 * @return the expression used to construct this {@link Calculable}
	 */
	public String getExpression();

	/**
	 * set a variable value for the calculation
	 * 
	 * @param name
	 *            the variable name
	 * @param value
	 *            the value of the variable
	 */
	public void setVariable(String name, double value);
	
	/**
	 * Determines if the given variable exists.
	 * @param name - name of the variable.
	 * @return TRUE if it does, FALSE otherwise.
	 */
	public boolean containsVariable(String name);
}