ó ù`]c@sˆddlmZddlZddlZddlmZdddd„Zd„Zd„Z dZ dd „Z e d kr„e ƒndS( iÿÿÿÿ(tprint_functionN(t NonterminalcCsa|s|jƒ}n|dkr-tj}nt||g|ƒ}|r]tj||ƒ}n|S(sm 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(tstarttNonetsystmaxsizet _generate_allt itertoolstislice(tgrammarRtdepthtntiter((s2lib/python2.7/site-packages/nltk/parse/generate.pytgenerates   ccs˜|ryOxHt||d|ƒD]0}x't||d|ƒD]}||Vq=Wq WWq”tk r‹}|jdkr…tdƒ‚qŒ‚q”XngVdS(Niis maximum recursion depth exceededs7The grammar has rule(s) that yield infinite recursion!!(t _generate_oneRt RuntimeErrortmessage(R titemsR tfrag1tfrag2t_error((s2lib/python2.7/site-packages/nltk/parse/generate.pyR(s  ccsv|dkrrt|tƒrgxQ|jd|ƒD]2}x)t||jƒ|dƒD] }|VqQWq.Wqr|gVndS(Nitlhsi(t isinstanceRt productionsRtrhs(R titemR tprodtfrag((s2lib/python2.7/site-packages/nltk/parse/generate.pyR:s  #sš 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' icCs‡ddlm}td|fƒttƒ|jtƒ}xFtt|d|ƒdƒD])\}}td|dj|ƒfƒqVWdS(Niÿÿÿÿ(tCFGs3Generating the first %d sentences for demo grammar:R is%3d. %st (t nltk.grammarRtprintt demo_grammart fromstringt enumerateR tjoin(tNRR R tsent((s2lib/python2.7/site-packages/nltk/parse/generate.pytdemoOs  (t__main__( t __future__RRRRRRR RRR R&t__name__(((s2lib/python2.7/site-packages/nltk/parse/generate.pyt s