Function General_Array_to_Cumulative_Array

methods/array_ops/src/pg_gp/array_ops.c:2016–2108

* @brief Transforms an array to another array using cumulative operations. * * @param v1 Array. * @param initial Parameter. * @param element_function Map function. * @returns Transformed array. */

 * @returns Transformed array.
 */
ArrayType*
General_Array_to_Cumulative_Array(
        ArrayType *v1,
        Datum initial,
        Datum(*element_function)(Datum,Oid,Datum,Oid,Datum,Oid)) {

    // dimensions
    int ndims1 = ARR_NDIM(v1);
    if (ndims1 == 0) {
        elog(WARNING, "input are empty arrays.");
        return v1;
    }
    int ndims = ndims1;
    int *lbs1 = ARR_LBOUND(v1);
    int *dims1 = ARR_DIMS(v1);
    int *dims = (int *) palloc(ndims * sizeof(int));
    int *lbs = (int *) palloc(ndims * sizeof(int));
    int i = 0;
    for (i = 0; i < ndims; i ++) {
        dims[i] = dims1[i];
        lbs[i] = lbs1[i];
    }
    int nitems = ArrayGetNItems(ndims, dims);

    // nulls
    if (ARR_HASNULL(v1)) {
        ereport(ERROR, (errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
                        errmsg("arrays cannot contain nulls"),
                        errdetail("Arrays with element value NULL are not allowed.")));
    }

    // type
    Oid element_type = ARR_ELEMTYPE(v1);
    TypeCacheEntry *typentry = lookup_type_cache(element_type,TYPECACHE_CMP_PROC_FINFO);
    int type_size = typentry->typlen;
    bool typbyval = typentry->typbyval;
    char typalign = typentry->typalign;

    // allocate
    Datum *result = NULL;
    switch (element_type) {
        case INT2OID:
        case INT4OID:
        case INT8OID:
        case FLOAT4OID:
        case FLOAT8OID:
        case NUMERICOID:
            result = (Datum *)palloc(nitems * sizeof(Datum));break;
        default:
            ereport(ERROR, (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
                            errmsg("type is not supported"),
                            errdetail("Arrays with element type %s are not supported.",
                                      format_type_be(element_type))));
            break;
    }

    // iterate
    Datum *resultp = result;