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// AbstractReference.java
// (C) 2009 by Michael Peter Christen; mc@yacy.net, Frankfurt a. M., Germany
// first published 14.04.2009 on http://yacy.net
//
// This is a part of YaCy, a peer-to-peer based web search engine
//
// $LastChangedDate$
// $LastChangedRevision$
// $LastChangedBy$
//
// LICENSE
//
// 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; either version 2 of the License, or
// (at your option) any later version.
//
// 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
package net.yacy.kelondro.rwi;
import java.util.Iterator;
import net.yacy.cora.util.ConcurrentLog;
public abstract class AbstractReference implements Reference {
/**
* The average distance (in words) between search query terms for multi word searches.
* @return word distance
*/
@Override
public int distance() {
// check if positions have been joined
if (positions() == null || positions().isEmpty()) return 0;
int d = 0;
Iterator<Integer> i = positions().iterator();
int s0 = posintext(); // init with own positon
int s1;
while (i.hasNext()) {
s1 = i.next();
if (s0 > 0) d += Math.abs(s0 - s1);
s0 = s1;
}
// despite first line checks for size < 2 Arithmetic exception div by zero occured (1.91/9278 2016-10-19)
// added d == 0 condition as protection for this (which was in all above tests the case)
try {
return d == 0 ? 0 : d / positions().size();
} catch (ArithmeticException ex) {
ConcurrentLog.fine("AbstractReference", "word distance calculation:" + ex.getMessage());
return 0;
}
}
@Override
public boolean isOlder(final Reference other) {
if (other == null) return false;
if (this.lastModified() < other.lastModified()) return true;
return false;
}
}
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