package org.eclipse.jst.jsf.common.internal.strategy;

/**
 * A strategy that takes an INPUT, performs a calculation on it, and returns
 * an OUTPUT
 * @author cbateman
 *
 * @param <INPUT>
 * @param <OUTPUT>
 */
public interface ISimpleStrategy<INPUT, OUTPUT>
{
    /**
     * Perform the algorithm on input and return OUTPUT.  This type of
     * operation should avoid side-effects, but may throw exceptions.
     * 
     * @param input
     * @return the result of the strategy algorithm
     * @throws Exception implementers should narrow what exceptions are thrown.
     */
    public OUTPUT perform(INPUT input) throws Exception;
    
    /**
     * @return the single value that perform will return if it cannot calculate
     * a meaningful result for an input.  The value must be unique, the same
     * for all inputs and must be testable using the '==' operator.
     */
    public OUTPUT getNoResult();
}