Function cube_inter

contrib/cube/cube.c:821–894

cube_inter */

/* cube_inter */
Datum
cube_inter(PG_FUNCTION_ARGS)
{
	NDBOX	   *a = PG_GETARG_NDBOX_P(0);
	NDBOX	   *b = PG_GETARG_NDBOX_P(1);
	NDBOX	   *result;
	bool		swapped = false;
	int			i;
	int			dim;
	int			size;

	/* swap the arguments if needed, so that 'a' is always larger than 'b' */
	if (DIM(a) < DIM(b))
	{
		NDBOX	   *tmp = b;

		b = a;
		a = tmp;
		swapped = true;
	}
	dim = DIM(a);

	size = CUBE_SIZE(dim);
	result = (NDBOX *) palloc0(size);
	SET_VARSIZE(result, size);
	SET_DIM(result, dim);

	/* First compute intersection of the dimensions present in both args */
	for (i = 0; i < DIM(b); i++)
	{
		result->x[i] = Max(Min(LL_COORD(a, i), UR_COORD(a, i)),
						   Min(LL_COORD(b, i), UR_COORD(b, i)));
		result->x[i + DIM(a)] = Min(Max(LL_COORD(a, i), UR_COORD(a, i)),
									Max(LL_COORD(b, i), UR_COORD(b, i)));
	}
	/* continue on the higher dimensions only present in 'a' */
	for (; i < DIM(a); i++)
	{
		result->x[i] = Max(0,
						   Min(LL_COORD(a, i), UR_COORD(a, i))
			);
		result->x[i + DIM(a)] = Min(0,
									Max(LL_COORD(a, i), UR_COORD(a, i))
			);
	}

	/*
	 * Check if the result was in fact a point, and set the flag in the datum
	 * accordingly. (we don't bother to repalloc it smaller)
	 */
	if (cube_is_point_internal(result))
	{
		size = POINT_SIZE(dim);
		result = repalloc(result, size);
		SET_VARSIZE(result, size);
		SET_POINT_BIT(result);
	}