def add(self, word, value):
"""
Add a Node with the given as the prefix key
and the value in the, if the word already
exists the value is unioned with the existing
word's value
:param word: The word to add in
:param value: The value to add for the Node
:return: True if added successfully else None
"""
prefix = Util.get_prefix(self.key, word)
"""
if current node matches the prefix we already have that word
"""
if prefix == word:
if self.value:
self.value = self.value.union(value)
else:
self.value = value
return True
"""
If current node is leaf and we need to add another leaf node,
split the current node
"""
if self.is_leaf:
if prefix:
self.children.append(
Node(self.key[len(prefix):], list(), value=self.value))
self.children.append(Node(word[len(prefix):], list(), value=value))
self.key = prefix
self.is_leaf = False
return True
"""
Check if word can be traced with current internal nodes
"""
if self.children:
for child in self.children:
if not prefix and Util.has_prefix(child.key, word):
return child.add(word, value)
if Util.has_prefix(child.key, word[len(prefix):]):
return child.add(word[len(prefix):], value)
"""
Add new external nodes
"""
if not prefix:
self.children.append(Node(word, list(), value=value))
elif prefix != self.key:
new_node = Node(word[len(prefix):], list(), value=value)
new_child_node = Node(self.key[len(prefix):],
self.children,
is_leaf=False)
self.children = list()
self.children.append(new_child_node)
self.children.append(new_node)
self.key = prefix
else:
self.children.append(Node(word[len(prefix):], list(), value=value))
self.is_leaf = False
return True
def test_4_has_prefix_if_absent(self):
# Arrange
string1 = "ack"
string2 = "hackathon"
# Act
result = Util.has_prefix(string1, string2)
# Assert
self.assertFalse(result, "Correct prefix not found")
def search(self, word):
"""
Recursively search a word in the from this Node
:param word: The word to search
:return: The node where the word matches after
tracing from the root else None
"""
prefix = Util.get_prefix(self.key, word)
if prefix == word:
return self
if self.is_leaf:
return None
if self.children:
for child in self.children:
if not prefix and Util.has_prefix(child.key, word):
return child.search(word)
if Util.has_prefix(child.key, word[len(prefix):]):
return child.search(word[len(prefix):])
