Function scoresOfGeoHashBox

src/geo.cpp:321–345

Compute the sorted set scores min (inclusive), max (exclusive) we should * query in order to retrieve all the elements inside the specified area * 'hash'. The two scores are returned by reference in *min and *max. */

 * query in order to retrieve all the elements inside the specified area
 * 'hash'. The two scores are returned by reference in *min and *max. */
void scoresOfGeoHashBox(GeoHashBits hash, GeoHashFix52Bits *min, GeoHashFix52Bits *max) {
    /* We want to compute the sorted set scores that will include all the
     * elements inside the specified Geohash 'hash', which has as many
     * bits as specified by hash.step * 2.
     *
     * So if step is, for example, 3, and the hash value in binary
     * is 101010, since our score is 52 bits we want every element which
     * is in binary: 101010?????????????????????????????????????????????
     * Where ? can be 0 or 1.
     *
     * To get the min score we just use the initial hash value left
     * shifted enough to get the 52 bit value. Later we increment the
     * 6 bit prefis (see the hash.bits++ statement), and get the new
     * prefix: 101011, which we align again to 52 bits to get the maximum
     * value (which is excluded from the search). So we get everything
     * between the two following scores (represented in binary):
     *
     * 1010100000000000000000000000000000000000000000000000 (included)
     * and
     * 1010110000000000000000000000000000000000000000000000 (excluded).
     */
    *min = geohashAlign52Bits(hash);
    hash.bits++;
    *max = geohashAlign52Bits(hash);
}

/* Obtain all members between the min/max of this geohash bounding box.
 * Populate a geoArray of GeoPoints by calling geoGetPointsInRange().