/*
 *    Geotools2 - OpenSource mapping toolkit
 *    http://geotools.org
 *    (C) 2002, Geotools Project Managment Committee (PMC)
 *
 *    This library is free software; you can redistribute it and/or
 *    modify it under the terms of the GNU Lesser General Public
 *    License as published by the Free Software Foundation;
 *    version 2.1 of the License.
 *
 *    This library is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *    Lesser General Public License for more details.
 *
 */
package org.geotools.filter;

import org.geotools.feature.Feature;


/**
 * Defines an expression that holds a literal for return.
 *
 * @author Rob Hranac, Vision for New York
 * @author Chris Holmes, TOPP
 * @version $Id: LiteralExpression.java,v 1.3 2003/08/07 21:30:36 cholmesny Exp $
 */
public interface LiteralExpression extends Expression {
    /**
     * Sets the literal.
     *
     * @param literal The literal to store inside this expression.
     *
     * @throws IllegalFilterException This literal type is not in scope.
     */
    void setLiteral(Object literal)
        throws IllegalFilterException;

    /**
     * Gets the value of this literal.
     *
     * @param feature Required by the interface but not used.
     *
     * @return the literal held by this expression.  Ignores the passed in
     *         feature.
     */
    Object getValue(Feature feature);

    /**
     * Returns the literal type.
     *
     * @return the short representation of the literal expression type.
     */
    short getType();

    /**
     * Retrieves the literal of this expression.
     *
     * @return the literal held by this expression.
     */
    Object getLiteral();
}