source: josm/src/org/openstreetmap/josm/data/osm/DataSet.java@ 78

package org.openstreetmap.josm.data.osm;

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

import org.openstreetmap.josm.data.SelectionTracker;

/**
 * DataSet is the data behind the application. It can consists of only a few
 * points up to the whole osm database. DataSet's can be merged together, 
 * saved, (up/down/disk)loaded etc.
 *
 * Note, that DataSet is not an osm-primitive and so has no key association 
 * but a few members to store some information.
 * 
 * @author imi
 */
public class DataSet extends SelectionTracker {

        /**
         * All nodes goes here, even when included in other data (ways etc).
         * This enables the instant conversion of the whole DataSet by iterating over
         * this data structure.
         */
        public Collection<Node> nodes = new LinkedList<Node>();

        /**
         * All line segments goes here, even when they are in a way.
         */
        public Collection<LineSegment> lineSegments = new LinkedList<LineSegment>();

        /**
         * All ways (Streets etc.) in the DataSet. 
         * 
         * The nodes of the way segments of this way must be objects from 
         * the nodes list, however the way segments are stored only in the 
         * way list.
         */
        public Collection<Way> ways = new LinkedList<Way>();

        /**
         * @return A collection containing all primitives (except keys) of the
         * dataset.
         */
        public Collection<OsmPrimitive> allPrimitives() {
                Collection<OsmPrimitive> o = new LinkedList<OsmPrimitive>();
                o.addAll(nodes);
                o.addAll(lineSegments);
                o.addAll(ways);
                return o;
        }

        /**
         * @return A collection containing all not-deleted primitives (except keys).
         */
        public Collection<OsmPrimitive> allNonDeletedPrimitives() {
                Collection<OsmPrimitive> o = new LinkedList<OsmPrimitive>();
                for (OsmPrimitive osm : allPrimitives())
                        if (!osm.isDeleted())
                                o.add(osm);
                return o;
        }

        /**
         * Remove the selection of the whole dataset.
         */
        public void clearSelection() {
                clearSelection(nodes);
                clearSelection(lineSegments);
                clearSelection(ways);
        }

        /**
         * Return a list of all selected objects. Even keys are returned.
         * @return List of all selected objects.
         */
        @Override
        public Collection<OsmPrimitive> getSelected() {
                Collection<OsmPrimitive> sel = getSelected(nodes);
                sel.addAll(getSelected(lineSegments));
                sel.addAll(getSelected(ways));
                return sel;
        }

        /**
         * Remove the selection from every value in the collection.
         * @param list The collection to remove the selection from.
         */
        private void clearSelection(Collection<? extends OsmPrimitive> list) {
                if (list == null)
                        return;
                for (OsmPrimitive osm : list)
                        osm.setSelected(false);
        }

        /**
         * Return all selected items in the collection.
         * @param list The collection from which the selected items are returned.
         */
        private Collection<OsmPrimitive> getSelected(Collection<? extends OsmPrimitive> list) {
                Collection<OsmPrimitive> sel = new HashSet<OsmPrimitive>();
                if (list == null)
                        return sel;
                for (OsmPrimitive osm : list)
                        if (osm.isSelected() && !osm.isDeleted())
                                sel.add(osm);
                return sel;
        }
}