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class Node:
global_end = 0
string = ""
all = []
def __init__(self, data=None):
self.data = data
self.children = []
self.id = len(self.all)
self.all.append(self)
self.parent = None
self.link = None
def __str__(self):
tup = self.get_tuple()
link_str = "" if self.link is None else f" -> {self.link.id}"
if tup is not None:
j, i = tup
return f"[{self.id}, {self.data}, {self.string[j:i + 1]}{link_str}]"
return f"[{self.id} root{link_str}]"
def __repr__(self):
return f"[{self.id}]"
def print_children(self):
print(self, end=" contains: ")
for child in self.children:
print(child, end=", ")
def add_child(self, child):
if child:
child.parent = self
self.children.append(child)
def num_chars_deep(self):
if self.data is None:
return 0
else:
return self.parent.num_chars_deep() + self.edge_length()
def remove_child(self, child):
self.children.remove(child)
def bastardise(self):
self.parent.remove_child(self)
self.parent = None
def add_suffix_link(self, destination):
assert self.link is None
assert len(self.children) > 0
assert isinstance(destination, Node)
self.link = destination
def follow_link(self):
assert self.link is not None
return self.link
def get_tuple(self):
if self.data is not None and self.data[1] == "#":
return self.data[0], self.global_end
return self.data
def first_letter(self):
return self.string[self.data[0]]
def get_child(self, char):
for child in self.children:
if child.first_letter() == char:
return child
return None
def edge_length(self):
if self.data is None:
return 0
else:
substring = self.get_tuple()
return substring[1] - substring[0] + 1
def print_tree(self, spaces=0):
print(f"{self}")
for child in self.children:
print(f" " * spaces, end="")
child.print_tree(spaces=spaces + 1)
def branch_from_point(active_node, active_edge, active_length, j, need_link_to):
edge = active_node.get_child(active_edge)
edge.bastardise()
original_substr = edge.get_tuple()
edge.data = (edge.data[0] + active_length, edge.data[1])
mediator = Node((original_substr[0], original_substr[0] + active_length - 1))
active_node.add_child(mediator)
mediator.add_child(edge)
mediator.add_child(Node((j+1, '#')))
# assert j+1 != 12
return mediator
def traverse_down(string, substring, active_node, active_edge, active_length, remainder):
j, i = substring
traversed = 0
g = 0
char = ""
remainder -= 0 if active_node.data is None else active_node.data[0] + 1
while remainder > 0:
char = string[i + traversed]
path = None
if active_length > 0:
path = active_node.get_child(active_edge)
else:
path = active_node.get_child(char)
if path is None:
raise Exception(f"Tried to go down '{char}' from point: {active_node, active_edge, active_length}")
traversed += path.edge_length()
g = min(remainder, path.edge_length())
# if path is None:
# return active_node, active_edge, active_length
if remainder >= path.edge_length() - active_length:
active_node = path
print(active_node.link is None)
active_length = 0
active_edge = ''
remainder -= path.edge_length() - active_length
else:
active_length = remainder
active_edge = char if active_length != 0 else None
break
active_length = remainder
return active_node, active_edge, active_length
def char_match_after(char, active_node, active_edge, active_length):
if active_length < 1:
return active_node.get_child(char) is not None
edge = active_node.get_child(active_edge)
position = edge.data[0] + active_length
return Node.string[position] == char
def suffix_tree(string):
# string += "$"
Node.string = string
n = len(string)
last_j = 0
root = Node()
root.add_child(Node((0, '#')))
root.add_suffix_link(root)
need_link_to = root
active_node = root
active_edge = ""
active_length = 0
remainder = 0
for i in range(1, n):
# if active_node.link is not None:
# active_node = active_node.link
# if active_node == active_node.link:
# remainder -= 1
Node.global_end += 1 # Rule 1s implicitly
for j in range(last_j + 1, i + 1):
print(string[0:i + 1], end=": ")
print(active_node, active_edge, active_length)
# if 2 or more letter string, just match the last character at the current position (we already went
# there) i.e. i i think
char = string[i] if i - j <= 1 else string[i]
match = char_match_after(char, active_node, active_edge, active_length)
if match: # Rule 3
print(3, -j)
remainder += 1
active_node, active_edge, active_length = traverse_down(string, (j, i), active_node, active_edge,
active_length, remainder)
break
else: # Rule 2
print(2, -j)
# new_node = None
if active_length > 0: # If the pointer is on an edge
# if active_node.link is not None:
# active_node = active_node.link
new_node = branch_from_point(active_node, active_edge, active_length, j, need_link_to)
new_node.add_suffix_link(need_link_to)
need_link_to = new_node
print(f"*** I want to go from {repr(active_node)} -> {repr(active_node.link)} ***")
# if active_node.link is not None:
# active_node = active_node.link
else: # If the pointer is on a node
new_node = Node((j, '#'))
active_node.add_child(new_node)
active_edge = ""
remainder = max(remainder - 1, 0)
active_length = 0
last_j = j
print(f"{i=} '{string[i]}' => {(active_node, active_edge, active_length)}, {remainder}")
# print(f"{i=} '{string[i]}' => {(active_node, active_edge, active_length)}, {remainder}")
root.print_tree()
print("\n" * 10)
if __name__ == "__main__":
suffix_tree("abcabxabcd")
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