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yacy_search_server/source/de/anomic/kelondro/text/AbstractIndex.java

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// AbstractIndex.java
// -----------------------------
// (C) 2009 by Michael Peter Christen; mc@yacy.net, Frankfurt a. M., Germany
// first published 15.3.2009 on http://yacy.net
//
// This is a part of YaCy, a peer-to-peer based web search engine
//
// $LastChangedDate: 2006-04-02 22:40:07 +0200 (So, 02 Apr 2006) $
// $LastChangedRevision: 1986 $
// $LastChangedBy: orbiter $
//
// 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 de.anomic.kelondro.text;
import java.io.IOException;
import java.util.Iterator;
import java.util.Set;
import java.util.TreeSet;
import de.anomic.kelondro.order.Order;
public abstract class AbstractIndex implements Index {
public int remove(final Set<String> wordHashes, final String urlHash) throws IOException {
// remove the same url hashes for multiple words
// this is mainly used when correcting a index after a search
final Iterator<String> i = wordHashes.iterator();
int c = 0;
while (i.hasNext()) {
if (remove(i.next(), urlHash)) c++;
}
return c;
}
public void remove(final Set<String> wordHashes, final Set<String> urlHashes) throws IOException {
// remove the same url hashes for multiple words
// this is mainly used when correcting a index after a search
final Iterator<String> i = wordHashes.iterator();
while (i.hasNext()) {
remove(i.next(), urlHashes);
}
}
public synchronized TreeSet<ReferenceContainer> references(final String startHash, final boolean rot, int count) throws IOException {
// creates a set of indexContainers
// this does not use the cache
final Order<ReferenceContainer> containerOrder = new ReferenceContainerOrder(this.ordering().clone());
containerOrder.rotate(ReferenceContainer.emptyContainer(startHash, 0));
final TreeSet<ReferenceContainer> containers = new TreeSet<ReferenceContainer>(containerOrder);
final Iterator<ReferenceContainer> i = references(startHash, rot);
//if (ram) count = Math.min(size(), count);
ReferenceContainer container;
// this loop does not terminate using the i.hasNex() predicate when rot == true
// because then the underlying iterator is a rotating iterator without termination
// in this case a termination must be ensured with a counter
// It must also be ensured that the counter is in/decreased every loop
while ((count > 0) && (i.hasNext())) {
container = i.next();
if ((container != null) && (container.size() > 0)) {
containers.add(container);
}
count--; // decrease counter even if the container was null or empty to ensure termination
}
return containers; // this may return less containers as demanded
}
}