cfg.py 文件源码

def demo3():
    from nltk import Production
    (S, VP, NP, PP, P, N, Name, V, Det) = \
        nonterminals('S, VP, NP, PP, P, N, Name, V, Det')

    productions = (
        # Syntactic Productions
        Production(S, [NP, VP]),
        Production(NP, [Det, N]),
        Production(NP, [NP, PP]),
        Production(VP, [VP, PP]),
        Production(VP, [V, NP, PP]),
        Production(VP, [V, NP]),
        Production(PP, [P, NP]),
        Production(PP, []),

        Production(PP, ['up', 'over', NP]),

        # Lexical Productions
        Production(NP, ['I']),   Production(Det, ['the']),
        Production(Det, ['a']),  Production(N, ['man']),
        Production(V, ['saw']),  Production(P, ['in']),
        Production(P, ['with']), Production(N, ['park']),
        Production(N, ['dog']),  Production(N, ['statue']),
        Production(Det, ['my']),
        )

    t = Tk()
    def destroy(e, t=t): t.destroy()
    t.bind('q', destroy)
    p = ProductionList(t, productions)
    p.pack(expand=1, fill='both')
    p.add_callback('select', p.markonly)
    p.add_callback('move', p.markonly)
    p.focus()
    p.mark(productions[2])
    p.mark(productions[8])