Function General_Array_to_Struct

methods/array_ops/src/pg_gp/array_ops.c:1624–1701

------------------------------------------------------------------------ general helper functions ------------------------------------------------------------------------ * @brief Aggregates an array to a composite struct. * * @param v Array. * @param init_val An initial value for element_function. * @param element_function Transition function. * @param finalize_function Final function. * @r

 * @returns Whatever finalize_function returns.
 */
static Datum General_Array_to_Struct(ArrayType *v, void *init_val,
        void*(*element_function)(Datum,Oid,int,void*),
        Datum(*finalize_function)(void*,int,Oid)) {

    // dimensions
    int ndims = ARR_NDIM(v);
    if (ndims == 0) {
        elog(WARNING, "input are empty arrays.");
        return Float8GetDatum(0);
    }
    int *dims = ARR_DIMS(v);
    int nitems = ArrayGetNItems(ndims, dims);

    // type
    Oid element_type = ARR_ELEMTYPE(v);
    TypeCacheEntry *typentry = lookup_type_cache(element_type,TYPECACHE_CMP_PROC_FINFO);
    int type_size = typentry->typlen;
    bool typbyval = typentry->typbyval;
    char typalign = typentry->typalign;

    // iterate
    void* result = init_val;
    char *dat = ARR_DATA_PTR(v);
    int i = 0;
    int null_count = 0;
    int *lbs = ARR_LBOUND(v);
    if(ARR_HASNULL(v)){
        bits8 *bitmap = ARR_NULLBITMAP(v);
        int bitmask = 1;
        for (i = 0; i < nitems; i++) {
            /* Get elements, checking for NULL */
            if (!(bitmap && (*bitmap & bitmask) == 0)) {
                Datum elt = fetch_att(dat, typbyval, type_size);
                dat = att_addlength_pointer(dat, type_size, dat);
                dat = (char *) att_align_nominal(dat, typalign);

                // treating NaN as NULL
                if (!isnan(datum_float8_cast(elt,element_type))) {
                    result = element_function(elt,
                                              element_type,
                                              lbs[0] + i,
                                              result);
                } else {
                    null_count++;
                }
            }else{
                null_count++;
            }

            /* advance bitmap pointers if any */
            if (bitmap) {
                bitmask <<= 1;
                if (bitmask == 0x100) {
                    bitmap++;
                    bitmask = 1;
                }
            }
        }