gserialized_list_union()

LWGEOM * gserialized_list_union ( List *  list, float8  gridSize  )

static

Definition at line 268 of file lwgeom_union.c.

{
        int ngeoms = 0;
        LWGEOM **geoms;
        int32_t srid = SRID_UNKNOWN;
        bool first = true;
        int empty_type = 0;
        int has_z = LW_FALSE;
        ListCell *cell;
 
        if (list_length(list) == 0)
                return NULL;
 
        geoms = lwalloc(list_length(list) * sizeof(LWGEOM*));
        foreach (cell, list)
        {
                GSERIALIZED *gser;
                LWGEOM *geom;
 
                gser = (GSERIALIZED*)lfirst(cell);
                assert(gser);
                geom = lwgeom_from_gserialized(gser);
 
                if (!lwgeom_is_empty(geom))
                {
                        geoms[ngeoms++] = geom; /* no cloning */
                        if (first)
                        {
                                srid = lwgeom_get_srid(geom);
                                has_z = lwgeom_has_z(geom);
                                first = false;
                        }
                }
                else
                {
                        int type = lwgeom_get_type(geom);
                        if (type > empty_type)
                                empty_type = type;
                        if (srid == SRID_UNKNOWN)
                                srid = lwgeom_get_srid(geom);
                }
        }
 
        if (ngeoms > 0)
        {
                /*
                 * Create a collection and pass it into cascaded union
                 */
                LWCOLLECTION *col = lwcollection_construct(COLLECTIONTYPE, srid, NULL, ngeoms, geoms);
                LWGEOM *result = lwgeom_unaryunion_prec(lwcollection_as_lwgeom(col), gridSize);
                if (!result)
                        lwcollection_free(col);
                return result;
        }
 
        /*
         * Only empty geometries in the list,
         * create geometry with largest type number or return NULL
         */
        return (empty_type > 0)
                ? lwgeom_construct_empty(empty_type, srid, has_z, 0)
                : NULL;
}

References COLLECTIONTYPE, LW_FALSE, lwalloc(), lwcollection_as_lwgeom(), lwcollection_construct(), lwcollection_free(), lwgeom_construct_empty(), lwgeom_from_gserialized(), lwgeom_get_srid(), lwgeom_get_type(), lwgeom_has_z(), lwgeom_is_empty(), lwgeom_unaryunion_prec(), result, and SRID_UNKNOWN.

Referenced by pgis_geometry_union_parallel_finalfn().

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