cyk.py

class Production(object):
    def __init__(self, *terms):
        self.terms = terms
    def __len__(self):
        return len(self.terms)
    def __getitem__(self, index):
        return self.terms[index]
    def __iter__(self):
        return iter(self.terms)
    def __repr__(self):
        return " ".join(str(t) for t in self.terms)
    def __eq__(self, other):
        if not isinstance(other, Production):
            return False
        return self.terms == other.terms
    def __ne__(self, other):
        return not (self == other)
    def __hash__(self):
        return hash(self.terms)

class Rule(object):
    def __init__(self, name, *productions):
        self.name = name
        self.productions = list(productions)
    def __str__(self):
        return self.name
    def __repr__(self):
        return "%s -> %s" % (self.name, " | ".join(repr(p) for p in self.productions))
    def add(self, *productions):
        self.productions.extend(productions)

grammar = 


def cfg_to_cnf(start):
    S0 = Rule("S0", Production(start))