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NodeValueIndexCursor.java
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NodeValueIndexCursor.java
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/*
* Copyright (c) 2002-2018 "Neo Technology,"
* Network Engine for Objects in Lund AB [http://neotechnology.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.internal.kernel.api;
import org.neo4j.values.storable.Value;
import static org.neo4j.values.storable.Values.NO_VALUE;
/**
* Cursor for scanning the property values of nodes in a schema index.
* <p>
* Usage pattern:
* <pre><code>
* int nbrOfProps = cursor.numberOfProperties();
* Value[] values = new Value[nbrOfProps];
* while ( cursor.next() )
* {
* if ( cursor.hasValue() )
* {
* for ( int i = 0; i < nbrOfProps; i++ )
* {
* values[i] = cursor.propertyValue( i );
* }
* }
* else
* {
* values[i] = getPropertyValueFromStore( cursor.nodeReference(), cursor.propertyKey( i ) )
* }
*
* doWhatYouWantToDoWith( values );
* }
* </code></pre>
*/
public interface NodeValueIndexCursor extends NodeIndexCursor
{
/**
* @return the number of properties accessible within the index, and thus from this cursor.
*/
int numberOfProperties();
int propertyKey( int offset );
/**
* Check before trying to access values with {@link #propertyValue(int)}. Result can change with each call to {@link #next()}.
*
* @return {@code true} if {@link #propertyValue(int)} can be used to get property value on cursor's current location,
* else {@code false}.
*/
boolean hasValue();
Value propertyValue( int offset );
class Empty implements NodeValueIndexCursor
{
@Override
public void node( NodeCursor cursor )
{
}
@Override
public long nodeReference()
{
return -1L;
}
@Override
public boolean next()
{
return false;
}
@Override
public boolean shouldRetry()
{
return false;
}
@Override
public void close()
{
}
@Override
public boolean isClosed()
{
return false;
}
@Override
public int numberOfProperties()
{
return 0;
}
@Override
public int propertyKey( int offset )
{
return -1;
}
@Override
public boolean hasValue()
{
return false;
}
@Override
public Value propertyValue( int offset )
{
return NO_VALUE;
}
}
NodeValueIndexCursor EMPTY = new Empty();
}