Function mda_next_tuple

src/backend/utils/adt/arrayutils.c:199–217

* Generates the tuple that is lexicographically one greater than the current * n-tuple in "curr", with the restriction that the i-th element of "curr" is * less than the i-th element of "span". * * Returns -1 if no next tuple exists, else the subscript position (0..n-1) * corresponding to the dimension to advance along. * * We assume caller has validated dimensions, so overflow is impossibl

 * We assume caller has validated dimensions, so overflow is impossible
 */
int
mda_next_tuple(int n, int *curr, const int *span)
{
	int			i;

	if (n <= 0)
		return -1;

	curr[n - 1] = (curr[n - 1] + 1) % span[n - 1];
	for (i = n - 1; i && curr[i] == 0; i--)
		curr[i - 1] = (curr[i - 1] + 1) % span[i - 1];

	if (i)
		return i;
	if (curr[0])
		return 0;

	return -1;
}

/*
 * ArrayGetIntegerTypmods: verify that argument is a 1-D cstring array,