001    /*
002     *    GeoAPI - Java interfaces for OGC/ISO standards
003     *    http://www.geoapi.org
004     *
005     *    Copyright (C) 2006-2012 Open Geospatial Consortium, Inc.
006     *    All Rights Reserved. http://www.opengeospatial.org/ogc/legal
007     *
008     *    Permission to use, copy, and modify this software and its documentation, with
009     *    or without modification, for any purpose and without fee or royalty is hereby
010     *    granted, provided that you include the following on ALL copies of the software
011     *    and documentation or portions thereof, including modifications, that you make:
012     *
013     *    1. The full text of this NOTICE in a location viewable to users of the
014     *       redistributed or derivative work.
015     *    2. Notice of any changes or modifications to the OGC files, including the
016     *       date changes were made.
017     *
018     *    THIS SOFTWARE AND DOCUMENTATION IS PROVIDED "AS IS," AND COPYRIGHT HOLDERS MAKE
019     *    NO REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
020     *    TO, WARRANTIES OF MERCHANTABILITY OR FITNESS FOR ANY PARTICULAR PURPOSE OR THAT
021     *    THE USE OF THE SOFTWARE OR DOCUMENTATION WILL NOT INFRINGE ANY THIRD PARTY
022     *    PATENTS, COPYRIGHTS, TRADEMARKS OR OTHER RIGHTS.
023     *
024     *    COPYRIGHT HOLDERS WILL NOT BE LIABLE FOR ANY DIRECT, INDIRECT, SPECIAL OR
025     *    CONSEQUENTIAL DAMAGES ARISING OUT OF ANY USE OF THE SOFTWARE OR DOCUMENTATION.
026     *
027     *    The name and trademarks of copyright holders may NOT be used in advertising or
028     *    publicity pertaining to the software without specific, written prior permission.
029     *    Title to copyright in this software and any associated documentation will at all
030     *    times remain with copyright holders.
031     */
032    package org.opengis.filter.expression;
033    
034    // Annotations
035    import org.opengis.annotation.XmlElement;
036    
037    
038    /**
039     * Instances of this interface provide a constant, literal value that can be
040     * used in expressions.
041     * <p>
042     * The {@link #evaluate evaluate} method of this class must return the same
043     * value as {@link #getValue()}.
044     * </p>
045     * <p>
046     * It should be noted that content of getValue() may be persisted with with
047     * XML based technologies. As an example a geoapi Geometry may be written out
048     * uding GML3, while a JTS Geometry may be written out using GML2. You should
049     * not assume that the same instance will be made available to all callers,
050     * please limit your self to pure data objects and don't use Literal to pass
051     * state or operations between systems.
052     * <p>
053     *
054     * @version <A HREF="http://www.opengis.org/docs/02-059.pdf">Implementation specification 1.0</A>
055     * @author Chris Dillard (SYS Technologies)
056     * @since GeoAPI 2.0
057     */
058    @XmlElement("Literal")
059    public interface Literal extends Expression {
060        /**
061         * Returns the constant value held by this object.
062         */
063        Object getValue();
064    
065    }