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 // Annotation
035 import org.opengis.annotation.Extension;
036
037
038 /**
039 * Visitor with {@code visit} methods to be called by {@link Expression#accept Expression.accept(...)}.
040 * <p>
041 * Please note that a generic visit( Expression ) entry point has not been provided, although Expression
042 * forms a heirarchy for your convience it is not an open heirarchy. If you need to extend this system
043 * please make use of {code Function}, this will allow extention while remaining standards complient.
044 * </p>
045 * <p>
046 * It is very common for a single instnace to implement both ExpressionVisitor and FilterVisitor.
047 * </p>
048 *
049 * @version <A HREF="http://www.opengis.org/docs/02-059.pdf">Implementation specification 1.0</A>
050 * @author Chris Dillard (SYS Technologies)
051 * @since GeoAPI 2.0
052 */
053 @Extension
054 public interface ExpressionVisitor {
055 /**
056 * Used to visit a Expression.NIL, also called for <code>null</code> where an
057 * expression is expected.
058 * <p>
059 * This is particularly useful when doing data transformations, as an example when
060 * using a StyleSymbolizer Expression.NIL can be used to represent the default
061 * stroke color.
062 * </p>
063 * @param extraData
064 * @return implementation specific
065 */
066 Object visit(NilExpression expression, Object extraData);
067 Object visit(Add expression, Object extraData);
068 Object visit(Divide expression, Object extraData);
069 Object visit(Function expression, Object extraData);
070 Object visit(Literal expression, Object extraData);
071 Object visit(Multiply expression, Object extraData);
072 Object visit(PropertyName expression, Object extraData);
073 Object visit(Subtract expression, Object extraData);
074 }