package mula

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Standard Universal Levenshtein Automaton

type nfa_state

Abstract type for the state of the atomata.

val start : k:int -> str:St.t -> nfa_state

start ~k ~str produces the starting state of the atomaton for edit distance k. Here k must not be negative and must not be greater (Sys.int_size - 1) / 2.

val feed : nfa_state -> ch:St.ch -> nfa_state

feed nfa ch produces a new state where the atomaton has been fed the character ch.

val current_error : nfa_state -> int option

current_error nfa produces Some n if the current error count recorded by the nfa is a number n, or None if the error count is larger than the limit k that the nfa was started with. current_error nfa may be smaller than end_input nfa, since it does not account for delete operations at the end of the fed string.

val end_input : nfa_state -> int option

end_input nfa computes the edit distance between the starting string and the string fed to nfa. It produces Some n if the edit distance in a number n that is less than the limit k that the automaton was started with, and None otherwise.

val feed_str : nfa_state -> str:St.t -> nfa_state

feed_str nfa ~str produces a new state where the atomaton has been fed the characters from the string str.

val get_distance : k:int -> St.t -> St.t -> int option

get_distance ~k str1 str2 computes the edit distance between two strings. It creates an atomaton with limit k and str1, and then feeds it the string str2, and thet outputs the result of calling end_input on the nfa.

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