class SweepLineStatus:
""" Implemented with AVLTree. """
def __init__(self):
self.tree = AVLTree()
self.size = 0
def add_segment(self, segment: Segment) -> bool:
res = self.tree.insert(segment)
if res:
self.size += 1
return res
def remove_segment(self, segment: Segment) -> bool:
res = self.tree.delete(segment)
if res:
self.size -= 1
return res
def get_above_neighbor(self, segment: Segment) -> Optional[Segment]:
current = self.tree.find(segment)
assert (current is not None)
above = self.tree.successor(current)
if above is not None:
return above.key
return None
def get_below_neighbor(self, segment: Segment) -> Optional[Segment]:
current = self.tree.find(segment)
assert (current is not None)
below = self.tree.predecessor(current)
if below is not None:
return below.key
return below
def intersection_with_upper(self, segment: Segment) -> Optional[Point]:
current = self.tree.find(segment)
assert (current is not None)
# Successor, because upper's y coordinate is bigger
upper = self.tree.successor(current)
if upper is None:
return None
else:
point = calculate_intersection_point(upper.key, segment)
if point is None:
return None
return point
def intersection_with_lower(self, segment: Segment) -> Optional[Point]:
current = self.tree.find(segment)
assert (current is not None)
lower = self.tree.predecessor(current)
if lower is None:
return None
else:
point = calculate_intersection_point(lower.key, segment)
if point is None:
return None
return point
def reach_intersection_of(self, upper: Segment, lower: Segment):
upper_node = self.tree.find(upper)
lower_node = self.tree.find(lower)
temp_key = upper_node.key
upper_node.key = lower_node.key
lower_node.key = temp_key
