/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package org.apache.tinkerpop.gremlin.structure;
/**
* {@link Direction} is used to denote the direction of an {@link Edge} or location of a {@link Vertex} on an
* {@link Edge}. For example:
* <p/>
* <pre>
* gremlin--knows-->rexster
* </pre>
* is an {@link Direction#OUT} {@link Edge} for Gremlin and an {@link Direction#IN} edge for Rexster. Moreover, given
* that {@link Edge}, Gremlin is the {@link Direction#OUT} {@link Vertex} and Rexster is the {@link Direction#IN}
* {@link Vertex}.
*
* @author Marko A. Rodriguez (http://markorodriguez.com)
* @author Stephen Mallette (http://stephen.genoprime.com)
*/
public enum Direction {
/**
* Refers to an outgoing direction.
*/
OUT,
/**
* Refers to an incoming direction.
*/
IN,
/**
* Refers to either direction ({@link #IN} or {@link #OUT}).
*/
BOTH;
/**
* The actual direction of an {@link Edge} may only be {@link #IN} or {@link #OUT}, as defined in this array.
*/
public static final Direction[] proper = new Direction[]{OUT, IN};
/**
* Produce the opposite representation of the current {@code Direction} enum.
*/
public Direction opposite() {
if (this.equals(OUT))
return IN;
else if (this.equals(IN))
return OUT;
else
return BOTH;
}
}