/*
* Copyright (c) 2008-2010 "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 Affero 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 Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package org.neo4j.graphmatching;
import java.util.Arrays;
import java.util.Collection;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;
import org.neo4j.graphdb.Node;
import org.neo4j.graphmatching.filter.AbstractFilterExpression;
import org.neo4j.graphmatching.filter.FilterBinaryNode;
import org.neo4j.graphmatching.filter.FilterExpression;
import org.neo4j.graphmatching.filter.FilterValueGetter;
import org.neo4j.helpers.Predicate;
import org.neo4j.helpers.collection.FilteringIterable;
/**
* The PatternMatcher is the engine that performs the matching of a graph
* pattern with the actual graph.
*/
public class PatternMatcher
{
private static PatternMatcher matcher = new PatternMatcher();
private PatternMatcher()
{
}
/**
* Get the sole instance of the {@link PatternMatcher}.
*
* @return the instance of {@link PatternMatcher}.
*/
public static PatternMatcher getMatcher()
{
return matcher;
}
/**
* Find occurrences of the pattern defined by the given {@link PatternNode}
* where the given {@link PatternNode} starts matching at the given
* {@link Node}.
*
* @param start the {@link PatternNode} to start matching at.
* @param startNode the {@link Node} to start matching at.
* @return all matching instances of the pattern.
*/
public Iterable<PatternMatch> match( PatternNode start,
Node startNode )
{
return match( start, startNode, null );
}
/**
* Find occurrences of the pattern defined by the given {@link PatternNode}
* where the given {@link PatternNode} starts matching at the given
* {@link Node}.
*
* @param start the {@link PatternNode} to start matching at.
* @param startNode the {@link Node} to start matching at.
* @param objectVariables mapping from names to {@link PatternNode}s.
* @return all matching instances of the pattern.
*/
public Iterable<PatternMatch> match( PatternNode start,
Node startNode, Map<String, PatternNode> objectVariables )
{
return match( start, startNode, objectVariables,
( Collection<PatternNode> ) null );
}
/**
* Find occurrences of the pattern defined by the given {@link PatternNode}
* where the given {@link PatternNode} starts matching at the given
* {@link Node}.
*
* @param start the {@link PatternNode} to start matching at.
* @param objectVariables mapping from names to {@link PatternNode}s.
* @param optional nodes that form sub-patterns connected to this pattern.
* @return all matching instances of the pattern.
*/
public Iterable<PatternMatch> match( PatternNode start,
Map<String, PatternNode> objectVariables,
PatternNode... optional )
{
return match( start, objectVariables,
Arrays.asList( optional ) );
}
/**
* Find occurrences of the pattern defined by the given {@link PatternNode}
* where the given {@link PatternNode} starts matching at the given
* {@link Node}.
*
* @param start the {@link PatternNode} to start matching at.
* @param objectVariables mapping from names to {@link PatternNode}s.
* @param optional nodes that form sub-patterns connected to this pattern.
* @return all matching instances of the pattern.
*/
public Iterable<PatternMatch> match( PatternNode start,
Map<String, PatternNode> objectVariables,
Collection<PatternNode> optional )
{
Node startNode = start.getAssociation();
if ( startNode == null )
{
throw new IllegalStateException(
"Associating node for start pattern node is null" );
}
return match( start, startNode, objectVariables, optional );
}
/**
* Find occurrences of the pattern defined by the given {@link PatternNode}
* where the given {@link PatternNode} starts matching at the given
* {@link Node}.
*
* @param start the {@link PatternNode} to start matching at.
* @param startNode the {@link Node} to start matching at.
* @param objectVariables mapping from names to {@link PatternNode}s.
* @param optional nodes that form sub-patterns connected to this pattern.
* @return all matching instances of the pattern.
*/
public Iterable<PatternMatch> match( PatternNode start,
Node startNode, Map<String, PatternNode> objectVariables,
Collection<PatternNode> optional )
{
Node currentStartNode = start.getAssociation();
if ( currentStartNode != null && !currentStartNode.equals( startNode ) )
{
throw new IllegalStateException(
"Start patter node already has associated " +
currentStartNode + ", can not start with " + startNode );
}
Iterable<PatternMatch> result = null;
if ( optional == null || optional.size() < 1 )
{
result = new PatternFinder( this, start, startNode );
}
else
{
result = new PatternFinder( this, start, startNode, false,
optional );
}
if ( objectVariables != null )
{
// Uses the FILTER expressions
result = new FilteredPatternFinder( result, objectVariables );
}
return result;
}
/**
* Find occurrences of the pattern defined by the given {@link PatternNode}
* where the given {@link PatternNode} starts matching at the given
* {@link Node}.
*
* @param start the {@link PatternNode} to start matching at.
* @param startNode the {@link Node} to start matching at.
* @param objectVariables mapping from names to {@link PatternNode}s.
* @param optional nodes that form sub-patterns connected to this pattern.
* @return all matching instances of the pattern.
*/
public Iterable<PatternMatch> match( PatternNode start,
Node startNode, Map<String, PatternNode> objectVariables,
PatternNode... optional )
{
return match( start, startNode, objectVariables,
Arrays.asList( optional ) );
}
private static class SimpleRegexValueGetter implements FilterValueGetter
{
private PatternMatch match;
private Map<String, PatternNode> labelToNode =
new HashMap<String, PatternNode>();
private Map<String, String> labelToProperty =
new HashMap<String, String>();
SimpleRegexValueGetter( Map<String, PatternNode> objectVariables,
PatternMatch match, FilterExpression[] expressions )
{
this.match = match;
for ( FilterExpression expression : expressions )
{
mapFromExpression( expression );
}
this.labelToNode = objectVariables;
}
private void mapFromExpression( FilterExpression expression )
{
if ( expression instanceof FilterBinaryNode )
{
FilterBinaryNode node = ( FilterBinaryNode ) expression;
mapFromExpression( node.getLeftExpression() );
mapFromExpression( node.getRightExpression() );
}
else
{
AbstractFilterExpression pattern =
( AbstractFilterExpression ) expression;
labelToProperty.put( pattern.getLabel(),
pattern.getProperty() );
}
}
public String[] getValues( String label )
{
PatternNode pNode = labelToNode.get( label );
if ( pNode == null )
{
throw new RuntimeException( "No node for label '" + label +
"'" );
}
Node node = this.match.getNodeFor( pNode );
String propertyKey = labelToProperty.get( label );
if ( propertyKey == null )
{
throw new RuntimeException( "No property key for label '" +
label + "'" );
}
Object rawValue = node.getProperty( propertyKey, null );
if ( rawValue == null )
{
return new String[ 0 ];
}
Collection<Object> values =
ArrayPropertyUtil.propertyValueToCollection( rawValue );
String[] result = new String[ values.size() ];
int counter = 0;
for ( Object value : values )
{
result[ counter++ ] = ( String ) value;
}
return result;
}
}
private static class FilteredPatternFinder
extends FilteringIterable<PatternMatch>
{
public FilteredPatternFinder( Iterable<PatternMatch> source,
final Map<String, PatternNode> objectVariables )
{
super( source, new Predicate<PatternMatch>()
{
public boolean accept( PatternMatch item )
{
Set<PatternGroup> calculatedGroups = new HashSet<PatternGroup>();
for ( PatternElement element : item.getElements() )
{
PatternNode node = element.getPatternNode();
PatternGroup group = node.getGroup();
if ( calculatedGroups.add( group ) )
{
FilterValueGetter valueGetter = new SimpleRegexValueGetter(
objectVariables, item, group.getFilters() );
for ( FilterExpression expression : group.getFilters() )
{
if ( !expression.matches( valueGetter ) )
{
return false;
}
}
}
}
return true;
}
} );
}
}
}