org.elasticsearch.geometry.GeometryVisitor Maven / Gradle / Ivy
/*
* Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
* or more contributor license agreements. Licensed under the Elastic License
* 2.0 and the Server Side Public License, v 1; you may not use this file except
* in compliance with, at your election, the Elastic License 2.0 or the Server
* Side Public License, v 1.
*/
package org.elasticsearch.geometry;
import org.elasticsearch.geometry.utils.WellKnownText;
/**
* Support class for creating Geometry Visitors.
*
* This is an implementation of the Visitor pattern. The basic idea is to simplify adding new operations on Geometries, without
* constantly modifying and adding new functionality to the Geometry hierarchy and keeping it as lightweight as possible.
*
* It is a more object-oriented alternative to structures like this:
*
* if (obj instanceof This) {
* doThis((This) obj);
* } elseif (obj instanceof That) {
* doThat((That) obj);
* ...
* } else {
* throw new IllegalArgumentException("Unknown object " + obj);
* }
*
*
* The Visitor Pattern replaces this structure with Interface inheritance making it easier to identify all places that are using this
* structure, and making a shape a compile-time failure instead of runtime.
*
* See {@link WellKnownText#toWKT(Geometry)} for an example of how this interface is used.
*
* @see Visitor Pattern
*/
public interface GeometryVisitor {
T visit(Circle circle) throws E;
T visit(GeometryCollection collection) throws E;
T visit(Line line) throws E;
T visit(LinearRing ring) throws E;
T visit(MultiLine multiLine) throws E;
T visit(MultiPoint multiPoint) throws E;
T visit(MultiPolygon multiPolygon) throws E;
T visit(Point point) throws E;
T visit(Polygon polygon) throws E;
T visit(Rectangle rectangle) throws E;
}