fr.inria.edelweiss.kgraph.query.SorterImpl Maven / Gradle / Ivy

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package fr.inria.edelweiss.kgraph.query;

import java.util.List;

import fr.inria.edelweiss.kgram.api.core.Node;
import fr.inria.edelweiss.kgram.core.Exp;
import fr.inria.edelweiss.kgram.core.Query;
import fr.inria.edelweiss.kgram.core.Sorter;
import fr.inria.edelweiss.kgraph.core.Graph;

/**
 * Sort KGRAM edges in connected order before query process
 * Take cardinality into account
 * 
 * @author Olivier Corby, Edelweiss, INRIA 2011
 *
 */
public class SorterImpl extends Sorter {
	
	Graph graph;
	
	SorterImpl(){}
	
	SorterImpl(Graph g){
		graph = g;
	}
	
//	public static SorterImpl create(){
//		return new SorterImpl();
//	}
	
	public static SorterImpl create(Graph g){
		return new SorterImpl(g);
	}
	
	public void sort(Query q, Exp exp, List lVar, List lBind){
		super.sort(q, exp, lVar, lBind);
	}
	
	/**
	 * Refine std connected order by taking cardinality of edges into account
	 */
	protected boolean before(Query q, Exp e1, Exp e2, List lNode, List lVar, List lBind){
		int n1  = e1.nBind(lNode, lVar, lBind);
		int n2  = e2.nBind(lNode, lVar, lBind);

		if (n1 == 0 && n2 == 0){
			if (beforeBind(q, e2, e1)){
				return true;
			}
		}
		
		if (n1 == n2 && e1.isEdge() && e2.isEdge()){
			int s1 = graph.size(e1.getEdge().getEdgeNode());
			int s2 = graph.size(e2.getEdge().getEdgeNode());
			if (s2 < s1){
				return true;
			}
		}
		
		return n2 > n1;
	}
	
	public boolean leaveFirst(){
		return false;
	}
	
	

}