def incorporate(pattern, trie):
# incorporate takes a pattern and incorporates it as another branch
# of a preexisting trie.
# if the trie is empty, add a node.
if trie.O == []:
x = trie_methods.name()
trie.node(x)
# set the current node to the root.
x = trie_methods.root(trie)
# iterate through the pattern.
for s in pattern:
# if there is an existing edge matching the symbol, select it.
if trie_methods.edge_exists(s, x, trie):
f = trie_methods.select(s, x, trie)
# update the current node to that edge's codomain.
x = trie.cod[f]
else:
# if there is not an existing edge,
# create an edge with the current symbol.
y = trie_methods.name()
trie.node(y)
e = trie_methods.name()
trie.edge(e, x, y, s)
# update the current node to that edge's codomain.
x = trie.cod[e]
return trie
def test_method_normal(self):
s = 'c'
x = 'A'
trie = graph.Graph()
trie.node('A')
trie.node('B')
trie.node('C')
trie.node('D')
trie.node('E')
trie.edge('f', 'A', 'B', 'a')
trie.edge('g', 'A', 'C', 'c')
trie.edge('h', 'A', 'D', 'g')
trie.edge('i', 'B', 'E', 'c')
e = trie_methods.select(s, x, trie)
self.assertEqual(e, 'g')
def is_prefix(text, trie):
# is_prefix determines whether a given text, starting from the text's
# first character, matches a branch of
# the given trie, and is thus one of the patterns from which
# the trie was constructed.
if not (isinstance(text, str) or isinstance(trie, graph.Graph)):
raise TypeError('ERROR: is_prefix requires string and trie.')
else:
# set the current node to the root of the trie.
x = trie_methods.root(trie)
# add an extra space at the end of the text to ensure the algorithm
# runs to completion and identifies when it has arrived at a leaf.
text = text + ' '
# iterate through the symbols in the text.
for s in text:
# if the current node has arrived at a leaf,
# then a pattern matches this text.
if trie_methods.arrived(x, trie):
return True
# if the current node has not arrived at a leaf,
# but an edge exists matching
# the current symbol, select that edge and travel to
# that edge's codomain.
elif trie_methods.edge_exists(s, x, trie):
e = trie_methods.select(s, x, trie)
x = trie.cod[e]
else:
# if no such edge exists, the current text
# does not match any pattern.
return False