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NativeDistinctValuesProgressor.java
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NativeDistinctValuesProgressor.java
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/*
* Copyright (c) 2002-2018 "Neo4j,"
* Neo4j Sweden AB [http://neo4j.com]
*
* This file is part of Neo4j.
*
* Neo4j 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 3 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, see <http://www.gnu.org/licenses/>.
*/
package org.neo4j.kernel.impl.index.schema;
import java.io.IOException;
import java.io.UncheckedIOException;
import java.util.Collection;
import org.neo4j.cursor.RawCursor;
import org.neo4j.index.internal.gbptree.Hit;
public class NativeDistinctValuesProgressor<KEY extends NativeSchemaKey<KEY>, VALUE extends NativeSchemaValue> extends NativeIndexProgressor<KEY,VALUE>
{
private final SchemaLayout<KEY> layout;
private final KEY prev;
private boolean first = true;
private long countForCurrentValue;
private boolean last;
NativeDistinctValuesProgressor( RawCursor<Hit<KEY,VALUE>,IOException> seeker, NodeValueClient client,
Collection<RawCursor<Hit<KEY,VALUE>,IOException>> toRemoveFromOnClose, SchemaLayout<KEY> layout )
{
super( seeker, client, toRemoveFromOnClose );
this.layout = layout;
prev = layout.newKey();
}
@Override
public boolean next()
{
try
{
while ( seeker.next() )
{
KEY key = seeker.get().key();
try
{
if ( first )
{
first = false;
countForCurrentValue = 1;
}
else if ( layout.compareValue( prev, key ) == 0 )
{
// same as previous
countForCurrentValue++;
}
else
{
// different from previous
boolean accepted = client.acceptNode( countForCurrentValue, extractValues( prev ) );
countForCurrentValue = 1;
if ( accepted )
{
return true;
}
}
}
finally
{
layout.copyKey( key, prev );
}
}
boolean finalResult = !first && !last && client.acceptNode( countForCurrentValue, extractValues( prev ) );
last = true;
return finalResult;
}
catch ( IOException e )
{
throw new UncheckedIOException( e );
}
}
}