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LevelSelectorOrderer.java
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LevelSelectorOrderer.java
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/*
* Copyright (c) 2002-2016 "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.graphdb.traversal;
import java.util.concurrent.atomic.AtomicInteger;
import org.neo4j.graphdb.Direction;
import org.neo4j.graphdb.impl.traversal.AbstractSelectorOrderer;
public class LevelSelectorOrderer extends AbstractSelectorOrderer<LevelSelectorOrderer.Entry>
{
private final boolean stopDescentOnResult;
private final TotalDepth totalDepth = new TotalDepth();
private final int maxDepth;
public LevelSelectorOrderer( BranchSelector startSelector, BranchSelector endSelector,
boolean stopDescentOnResult, int maxDepth )
{
super( startSelector, endSelector );
this.stopDescentOnResult = stopDescentOnResult;
this.maxDepth = maxDepth;
}
@Override
protected Entry initialState()
{
return new Entry();
}
@Override
public TraversalBranch next( TraversalContext metadata )
{
TraversalBranch branch = nextBranchFromCurrentSelector( metadata, false );
Entry state = getStateForCurrentSelector();
AtomicInteger previousDepth = state.depth;
if ( branch != null && branch.length() == previousDepth.get() )
{ // Same depth as previous branch returned from this side.
return branch;
}
if ( branch != null )
{
totalDepth.set( currentSide(), branch.length() );
}
if ( (stopDescentOnResult && metadata.getNumberOfPathsReturned() > 0) ||
totalDepth.get() > maxDepth+1 )
{
nextSelector();
return null;
}
if ( branch != null )
{
previousDepth.set( branch.length() );
state.branch =branch;
}
BranchSelector otherSelector = nextSelector();
Entry otherState = getStateForCurrentSelector();
TraversalBranch otherBranch = otherState.branch;
if ( otherBranch != null )
{
otherState.branch = null;
return otherBranch;
}
otherBranch = otherSelector.next( metadata );
return otherBranch != null ? otherBranch : branch;
}
static class Entry
{
private final AtomicInteger depth = new AtomicInteger();
private TraversalBranch branch;
}
private static class TotalDepth
{
private int out;
private int in;
void set( Direction side, int depth )
{
switch ( side )
{
case OUTGOING: out = depth; break;
case INCOMING: in = depth; break;
}
}
int get()
{
return out+in;
}
}
}