def levenshtein_automata(tokens, k):
l = len(tokens)
nfa = NFA(states=set(range((l + 1) * (k + 1))))
# Insert forward edges
for i in range(l):
for j in range(k + 1):
nfa.add_transition((j * (l + 1)) + i, (j * (l + 1)) + i + 1,
tokens[i])
# Insert lifting edges
for row in range(k):
for col in range(l + 1):
nfa.add_transition((row * (l + 1)) + col,
((row + 1) * (l + 1)) + col, WILDCARD)
# Insert Diagnol
for row in range(k):
for col in range(l):
nfa.add_transition((row * (l + 1)) + col,
((row + 1) * (l + 1)) + col + 1, EPSILON)
nfa.add_transition((row * (l + 1)) + col,
((row + 1) * (l + 1)) + col + 1, WILDCARD)
nfa.set_start(0)
for i in range(k + 1):
nfa.make_final(i * (l + 1) + l)
nfa.normalize()
return nfa
