FiniteDomain.java

package aima.core.probability.domain;

import java.util.Set;

/**
 * A Domain over a countable/discrete and finite set of objects.
 * 
 * @author Ciaran O'Reilly
 * 
 */
public interface FiniteDomain extends DiscreteDomain {
	/**
	 * 
	 * @return a consistent ordered Set (e.g. LinkedHashSet) of the possible
	 *         values this domain can take on.
	 */
	Set<? extends Object> getPossibleValues();

	/**
	 * The possible values for a finite domain are to have a consistent ordering
	 * (whether they are actually ordered by value or not). This will return an
	 * offset into that ordering.
	 * 
	 * @param value
	 *            a value from the domain.
	 * @return an offset (starting from 0) into the consistent order of the set
	 *         of possible values.
	 * @exception IllegalArgumentException
	 *                if the value is not valid for the domain.
	 */
	int getOffset(Object value);

	/**
	 * 
	 * @param offset
	 *            an offset into the consistent ordering for this domain.
	 * @return the Object at the specified offset in this domains consistent
	 *         ordered set of values. null if the offset does not index the
	 *         domain correctly.
	 */
	Object getValueAt(int offset);
}