3 dM @sVddlZddlZddlmZdddZddZddZd Zdd d Ze d krRedS)N) NonterminalcCs<|s |j}|dkrtj}t||g|}|r8tj||}|S)am Generates an iterator of all sentences from a CFG. :param grammar: The Grammar used to generate sentences. :param start: The Nonterminal from which to start generate sentences. :param depth: The maximal depth of the generated tree. :param n: The maximum number of sentences to return. :return: An iterator of lists of terminal tokens. N)startsysmaxsize _generate_all itertoolsislice)grammarrdepthniterr 3/tmp/pip-build-v9q4h5k9/nltk/nltk/parse/generate.pygenerates  rccs|rzyFx@t||d|D],}x&t||dd|D]}||Vq2WqWWqtk rv}ztd|WYdd}~XqXngVdS)Nrz6The grammar has rule(s) that yield infinite recursion!) _generate_onerRecursionError RuntimeError)r itemsr Zfrag1Zfrag2errorr r rr'srccsP|dkrLt|trDx8|j|dD]}t||j|dEdHq Wn|gVdS)Nr)lhsr) isinstancerZ productionsrrhs)r itemr prodr r rr6s   rz S -> NP VP NP -> Det N PP -> P NP VP -> 'slept' | 'saw' NP | 'walked' PP Det -> 'the' | 'a' N -> 'man' | 'park' | 'dog' P -> 'in' | 'with' cCsfddlm}td|ftt|jt}x4tt||ddD]\}}td|dj|fq@WdS)Nr)CFGz3Generating the first %d sentences for demo grammar:)r rz%3d. %s ) nltk.grammarrprint demo_grammar fromstring enumeraterjoin)Nrr r sentr r rdemoJs   r&__main__)NNN)r) rrrrrrrr r&__name__r r r r s