source: josm/trunk/src/org/openstreetmap/josm/data/osm/visitor/CollectBackReferencesVisitor.java@ 407

// 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.Relation;
import org.openstreetmap.josm.data.osm.RelationMember;
import org.openstreetmap.josm.data.osm.Node;
import org.openstreetmap.josm.data.osm.OsmPrimitive;
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 implements Visitor {

        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.deleted || w.incomplete) continue;
                        for (Node n2 : w.nodes) {
                                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) {
                        for (RelationMember m : r.members) {
                                if (m.member == 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;
                                }
                        }
                }
        }
}