def delete(marker)
range = ranges[marker]
path_to_first_node = make_path
first_node = find(range.first, path_to_first_node)
cur_node = first_node
cur_level = first_node.top_level
while next_node_at_level_inside_range?(cur_node, cur_level, range)
while can_ascend_from?(cur_node, cur_level) && next_node_at_level_inside_range?(cur_node, cur_level + 1, range)
cur_level += 1
end
cur_node = unmark_forward_path_at_level(cur_node, cur_level, marker)
end
while node_inside_range?(cur_node, range)
while can_descend_from?(cur_level) && next_node_at_level_outside_range?(cur_node, cur_level, range)
cur_level -= 1
end
cur_node = unmark_forward_path_at_level(cur_node, cur_level, marker)
end
last_node = cur_node
first_node.endpoint_of.delete(marker)
if first_node.endpoint_of.empty?
first_node.delete(path_to_first_node)
end
last_node.endpoint_of.delete(marker)
if last_node.endpoint_of.empty?
path_to_last_node = make_path
find(range.last, path_to_last_node)
last_node.delete(path_to_last_node)
end
end