/**
Copyright (C) SYSTAP, LLC DBA Blazegraph 2006-2016. All rights reserved.
Contact:
SYSTAP, LLC DBA Blazegraph
2501 Calvert ST NW #106
Washington, DC 20008
licenses@blazegraph.com
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; version 2 of the License.
This program 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
/*
* Created on Feb 23, 2011
*/
package com.bigdata.bop.joinGraph.rto;
import java.util.Arrays;
/**
* An ordered array of bop identifiers which can be used as a signature for a
* join path segment. Unlike an <code>int[]</code>, instances of this class may
* be used safely in a hash map.
*
* @author <a href="mailto:thompsonbry@users.sourceforge.net">Bryan Thompson</a>
* @version $Id$
*/
public class PathIds {
final int[] ids;
/**
* The length of the path.
*/
public int length() {
return ids.length;
}
/**
* Convenience constructor.
*
* @param p
* A path.
*/
public PathIds(final Path p) {
this(p.getVertexIds());
}
/**
* Core constructor.
*
* @param ids
* The ordered set of vertex identifiers for some join path
* segment.
*/
public PathIds(final int[] ids) {
if (ids == null)
throw new IllegalArgumentException();
this.ids = ids;
}
/**
* Same path ids.
*/
@Override
public boolean equals(final Object o) {
if (this == o)
return true;
if (!(o instanceof PathIds)) {
return false;
}
return Arrays.equals(ids, ((PathIds) o).ids);
}
/**
* The hash code of an edge is the hash code of the vertex with the smaller
* hash code X 31 plus the hash code of the vertex with the larger hash
* code. This definition compensates for the arbitrary order in which the
* vertices may be expressed and also recognizes that the vertex hash codes
* are based on the bop ids, which are often small integers.
*/
@Override
public int hashCode() {
int h = hash;
if (h == 0) {
for (int id : ids) {
h = 31 * h + id;
}
hash = h;
}
return hash;
}
private int hash;
/**
* Return the path id array as a string.
*/
@Override
public String toString() {
return Arrays.toString(ids);
}
}