yacy_search_server/source/net/yacy/document/geolocation/IntegerGeoPoint.java

package net.yacy.document.geolocation;

/**
 * GeoPoint implementation with Integer accuracy
 */
public class IntegerGeoPoint implements GeoPoint {

    private final long latlon; // using one variable for the coordinate pair saves some space

    public IntegerGeoPoint(double lat, double lon) {
        this.latlon = (((long) coord2int(lat)) << 32) | (coord2int(lon));
    }


    public IntegerGeoPoint(int lat, int lon) {
        this.latlon = (((long) coord2int(lat / 1e6d)) << 32) | (coord2int(lon / 1e6d));
    }

    @Override
    public double lat() {
        return int2coord((int) (this.latlon >>> 32));
    }


    @Override
    public double lon() {
        return int2coord((int) (this.latlon & (Integer.MAX_VALUE)));
    }
    /**
     * get the implementation-dependent accuracy of the latitude
     * @return
     */
    @Override
    public double accuracyLat() {
        return Math.abs(int2coord(1) - int2coord(2));
    }

    /**
     * get the implementation-dependent accuracy of the longitude
     * @return
     */
    @Override
    public double accuracyLon() {
        return Math.abs(int2coord(1) - int2coord(2));
    }

    private static final double maxint = new Double(Integer.MAX_VALUE).doubleValue();
    private static final double upscale = maxint / 360.0d;

    private static final int coord2int(double coord) {
        return (int) ((coord + 180.0d) * upscale);
    }

    private static final double int2coord(int z) {
        return (z / upscale) - 180.0d;
    }

    /**
     * compute the hash code of a coordinate
     * this produces identical hash codes for locations that are close to each other
     */
    @Override
    public int hashCode() {
        return (int) ((this.latlon & Integer.MAX_VALUE) >> 1) + (int) (this.latlon >> 33);
    }

    /**
     * equality test that is needed to use the class inside HashMap/HashSet
     */
    @Override
    public boolean equals(final Object o) {
        if (!(o instanceof IntegerGeoPoint)) return false;
        IntegerGeoPoint oo = (IntegerGeoPoint) o;
        return (this.latlon == oo.latlon);
    }

    @Override
    public String toString() {
        return "[" + this.lat() + "," + this.lon() + "]";
    }

    public static void main(String[] args) {
        double lat = 13.419444d;
        double lon = 52.548611d;
        GeoPoint c = new IntegerGeoPoint(lat, lon);
        System.out.println(c.toString() + " #" + c.hashCode());
        System.out.println("error: lat: " + (Math.abs(c.lat() - lat) / meter) + " meter; lon: " + (Math.abs(c.lon() - lon) / meter) + " meter");
        System.out.println("accuracyLat = " + c.accuracyLat() / meter + " meter, accuracyLon = " + c.accuracyLon() / meter + " meter");
    }
}