def test_false(self):
x = 'A'
trie = graph.Graph()
trie.node('A')
trie.node('B')
trie.edge('f', 'A', 'B', 'c')
val = trie_methods.arrived(x, trie)
self.assertFalse(val)
def test_normal(self):
x = 'B'
trie = graph.Graph()
trie.node('A')
trie.node('B')
trie.edge('f', 'A', 'B', 'c')
val = trie_methods.arrived(x, trie)
self.assertTrue(val)
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