Method bit_and

src/common/classes/sparse_bitmap.h:714–825

template <typename T, typename InternalTypes>
SparseBitmap<T, InternalTypes>**
SparseBitmap<T, InternalTypes>::bit_and(SparseBitmap<T, InternalTypes>** bitmap1,
										SparseBitmap<T, InternalTypes>** bitmap2
)
{
	SparseBitmap *map1, *map2;

	// Handle the case when one or the other of the bitmaps is NULL
	if (!bitmap1 || !bitmap2 || !(map1 = *bitmap1) || !(map2 = *bitmap2)) {
		return NULL;
	}

	// Make sure we work on 2 different bitmaps
	fb_assert(map1 != map2);

	// First bitmap is singular. Test appropriate bit in second and return first
	if (map1->singular)
	{
		if (map2->test(map1->singular_value))
			return bitmap1;

		return NULL;
	}

	// Second bitmap is singular. Test appropriate bit in first and return second
	if (map2->singular)
	{
		if (map1->test(map2->singular_value))
			return bitmap2;

		return NULL;
	}

	SparseBitmap *source, *dest, **result;

	// If second bitmap seems smaller then use it as a target
	if (map1->tree.seemsBiggerThan(map2->tree))
	{
		dest = map2;
		source = map1;
		result = bitmap2;
	}
	else
	{
		dest = map1;
		source = map2;
		result = bitmap1;
	}

	bool destFound = dest->tree.getFirst();

	// Destination bitmap is empty. We have nothing to do thus return.
	if (!destFound)
		return result;

	bool sourceFound = source->tree.getFirst();

	// Both source and destination are empty. Return destination FWIW.