package org.eclipse.jst.jsf.common.sets.internal.provisional.mapping;

import java.util.Iterator;

import org.eclipse.jst.jsf.common.sets.internal.provisional.AxiomaticSet;

/**
 * A type of axiomatic set mapping that operates injectively on the output
 * set to create its result set.  Note that the injection (one-to-oneness)
 * of the mapping is based on Java objects and not on the value of the object.
 * Therefore, the result set is not guaranteed to be injective on the basis
 * of value.
 * 
 * For example, consider a set of integers:
 * 
 * X = {new Integer(4), new Integer(6), new Integer(9)}
 * 
 * an ObjectInjectiveSetMapping may be defined that maps this set
 * to a result based on:
 * 
 * map(x) = new Boolean(x < 8) for all x in X
 * 
 * An ObjectiveInjectiveSetMapping result set would look like this:
 * 
 * map(X) = {new Boolean(true), new Boolean(true), new Boolean(false)}
 * 
 * Note that boolean TRUE maps twice, so based on the value of the set members,
 * the mapping is not injective.  However, each Java object in X maps to a
 * distinct Java object in map(X)
 * 
 * This interface should not be implemented by clients. Clients should
 * sub-class AbstractObjectInjectiveSetMapping to avoid future API breakage.
 * 
 * @author cbateman
 *
 */
public interface ObjectInjectiveSetMapping extends AxiomaticSetMapping
{
    /**
     * This method optimizes the case where a client wants to apply some
     * mapping or constraint to each element of a set until a particular
     * condition applies and then stop.
     * 
     * Mapping's that implement this
     * interface should generally implement their map(set) method as:
     * 
     *  for (Iterator it = mapIterator(set); it.hasNext();)
     *  {
     *      result.add(doMapping(it.next));
     *  }
     *  
     * @param set
     * @return an iterator that allows a client to apply the mapping
     * one element of set at a time.  The iterator is immutable and should
     * throw UnsupportedOperationException if remove() is called.
     */
    public Iterator mapIterator(AxiomaticSet set);
}