ST_CollectionExtract()

Datum ST_CollectionExtract

(

PG_FUNCTION_ARGS

)

Definition at line 2715 of file lwgeom_functions_basic.c.

{
        GSERIALIZED *input = PG_GETARG_GSERIALIZED_P(0);
        GSERIALIZED *output;
        LWGEOM *lwgeom = lwgeom_from_gserialized(input);
        LWGEOM *lwcol = NULL;
        int type = PG_GETARG_INT32(1);
        int lwgeom_type = lwgeom->type;
 
        /* Ensure the right type was input */
        if (!(type == POINTTYPE || type == LINETYPE || type == POLYGONTYPE))
        {
                lwgeom_free(lwgeom);
                elog(ERROR, "ST_CollectionExtract: only point, linestring and polygon may be extracted");
                PG_RETURN_NULL();
        }
 
        /* Mirror non-collections right back */
        if (!lwgeom_is_collection(lwgeom))
        {
                /* Non-collections of the matching type go back */
                if (lwgeom_type == type)
                {
                        lwgeom_free(lwgeom);
                        PG_RETURN_POINTER(input);
                }
                /* Others go back as EMPTY */
                else
                {
                        lwcol = lwgeom_construct_empty(
                            type, lwgeom->srid, lwgeom_has_z(lwgeom), lwgeom_has_m(lwgeom));
                }
        }
        else
        {
                lwcol = lwcollection_as_lwgeom(lwcollection_extract((LWCOLLECTION *)lwgeom, type));
        }
 
        output = geometry_serialize((LWGEOM *)lwcol);
        lwgeom_free(lwgeom);
        lwgeom_free(lwcol);
 
        PG_RETURN_POINTER(output);
}

References geometry_serialize(), LINETYPE, lwcollection_as_lwgeom(), lwcollection_extract(), lwgeom_construct_empty(), lwgeom_free(), lwgeom_from_gserialized(), lwgeom_has_m(), lwgeom_has_z(), lwgeom_is_collection(), POINTTYPE, POLYGONTYPE, LWGEOM::srid, and LWGEOM::type.

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