pgis_accum_finalfn() [1/2]

Datum pgis_accum_finalfn	(	CollectionBuildState *	state,
		MemoryContext	mctx,
		__attribute__((__unused__)) FunctionCallInfo	fcinfo
	)

The final function reads the List of LWGEOM* from the aggregate memory context and constructs an Array using construct_md_array()

Definition at line 147 of file lwgeom_accum.c.

{
        ListCell *l;
        size_t nelems = 0;
        Datum *elems;
        bool *nulls;
        int16 elmlen;
        bool elmbyval;
        char elmalign;
        size_t i = 0;
        ArrayType *arr;
        int dims[1];
        int lbs[1] = {1};
 
        /* cannot be called directly because of internal-type argument */
        Assert(fcinfo->context &&
               (IsA(fcinfo->context, AggState) ||
                IsA(fcinfo->context, WindowAggState))
               );
 
        /* Retrieve geometry type metadata */
        get_typlenbyvalalign(state->geomOid, &elmlen, &elmbyval, &elmalign);
        nelems = list_length(state->geoms);
 
        /* Build up an array, because that's what we pass to all the */
        /* specific final functions */
        elems = palloc(nelems * sizeof(Datum));
        nulls = palloc(nelems * sizeof(bool));
 
        foreach (l, state->geoms)
        {
                LWGEOM *geom = (LWGEOM*)(lfirst(l));
                Datum elem = (Datum)0;
                bool isNull = true;
                if (geom)
                {
                        GSERIALIZED *gser = geometry_serialize(geom);
                        elem = PointerGetDatum(gser);
                        isNull = false;
                }
                elems[i] = elem;
                nulls[i] = isNull;
                i++;
 
                if (i >= nelems)
                        break;
        }
 
        /* Turn element array into PgSQL array */
        dims[0] = nelems;
        arr = construct_md_array(elems, nulls, 1, dims, lbs, state->geomOid,
                                 elmlen, elmbyval, elmalign);
 
        return PointerGetDatum(arr);
}

References CollectionBuildState::geomOid, and CollectionBuildState::geoms.