Example #1
0
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')
Example #3
0
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