source: josm/trunk/src/org/openstreetmap/josm/data/osm/visitor/CollectBackReferencesVisitor.java@ 2070

// License: GPL. Copyright 2007 by Immanuel Scholz and others
package org.openstreetmap.josm.data.osm.visitor;

import java.util.Collection;
import java.util.HashSet;

import org.openstreetmap.josm.data.osm.DataSet;
import org.openstreetmap.josm.data.osm.Node;
import org.openstreetmap.josm.data.osm.OsmPrimitive;
import org.openstreetmap.josm.data.osm.Relation;
import org.openstreetmap.josm.data.osm.RelationMember;
import org.openstreetmap.josm.data.osm.Way;

/**
 * Helper that collect all ways a node is part of.
 *
 * Deleted objects are not collected.
 *
 * @author imi
 */
public class CollectBackReferencesVisitor extends AbstractVisitor {

    private final DataSet ds;
    private final boolean indirectRefs;

    /**
     * The result list of primitives stored here.
     */
    public final Collection<OsmPrimitive> data = new HashSet<OsmPrimitive>();


    /**
     * Construct a back reference counter.
     * @param ds The dataset to operate on.
     */
    public CollectBackReferencesVisitor(DataSet ds) {
        this.ds = ds;
        this.indirectRefs = true;
    }

    public CollectBackReferencesVisitor(DataSet ds, boolean indirectRefs) {
        this.ds = ds;
        this.indirectRefs = indirectRefs;
    }

    public void visit(Node n) {
        for (Way w : ds.ways) {
            if (w.isDeleted() || w.incomplete) {
                continue;
            }
            for (Node n2 : w.getNodes()) {
                if (n == n2) {
                    data.add(w);
                    if (indirectRefs) {
                        visit(w);
                    }
                }
            }
        }
        checkRelationMembership(n);
    }

    public void visit(Way w) {
        checkRelationMembership(w);
    }

    public void visit(Relation r) {
        checkRelationMembership(r);
    }

    private void checkRelationMembership(OsmPrimitive p) {
        // FIXME - this might be a candidate for optimisation
        // if OSM primitives are made to hold a list of back
        // references.
        for (Relation r : ds.relations) {
            if (r.incomplete || r.isDeleted()) {
                continue;
            }
            for (RelationMember m : r.getMembers()) {
                if (m.getMember() == p) {
                    if (!data.contains(r)) {
                        data.add(r);
                        if (indirectRefs) {
                            // move up the tree (there might be relations
                            // referring to this relation)
                            checkRelationMembership(r);
                        }
                    }
                    break;
                }
            }
        }
    }
}