Function array_get_isnull

src/backend/utils/adt/arrayfuncs.c:4670–4678

* Check whether a specific array element is NULL * * nullbitmap: pointer to array's null bitmap (NULL if none) * offset: 0-based linear element number of array element */

 * offset: 0-based linear element number of array element
 */
static bool
array_get_isnull(const bits8 *nullbitmap, int offset)
{
	if (nullbitmap == NULL)
		return false;			/* assume not null */
	if (nullbitmap[offset / 8] & (1 << (offset % 8)))
		return false;			/* not null */
	return true;
}

/*
 * Set a specific array element's null-bitmap entry