Coverage for nltk.corpus.util : 81%

# Natural Language Toolkit: Corpus Reader Utility Functions 

# 

# Copyright (C) 2001-2012 NLTK Project 

# Author: Edward Loper <edloper@gradient.cis.upenn.edu> 

# URL: <http://www.nltk.org/> 

# For license information, see LICENSE.TXT 

###################################################################### 

#{ Lazy Corpus Loader 

###################################################################### 

import re 

import nltk 

TRY_ZIPFILE_FIRST = False 

class LazyCorpusLoader(object): 

    """ 

    A proxy object which is used to stand in for a corpus object 

    before the corpus is loaded.  This allows NLTK to create an object 

    for each corpus, but defer the costs associated with loading those 

    corpora until the first time that they're actually accessed. 

    The first time this object is accessed in any way, it will load 

    the corresponding corpus, and transform itself into that corpus 

    (by modifying its own ``__class__`` and ``__dict__`` attributes). 

    If the corpus can not be found, then accessing this object will 

    raise an exception, displaying installation instructions for the 

    NLTK data package.  Once they've properly installed the data 

    package (or modified ``nltk.data.path`` to point to its location), 

    they can then use the corpus object without restarting python. 

    """ 

    def __init__(self, name, reader_cls, *args, **kwargs): 

        from nltk.corpus.reader.api import CorpusReader 

        assert issubclass(reader_cls, CorpusReader) 

        self.__name = self.__name__ = name 

        self.__reader_cls = reader_cls 

        self.__args = args 

        self.__kwargs = kwargs 

    def __load(self): 

        # Find the corpus root directory. 

        zip_name = re.sub(r'(([^/]*)(/.*)?)', r'\2.zip/\1/', self.__name) 

        if TRY_ZIPFILE_FIRST: 

            try: 

                root = nltk.data.find('corpora/%s' % zip_name) 

            except LookupError: 

                raise 

                root = nltk.data.find('corpora/%s' % self.__name) 

        else: 

            try: 

                root = nltk.data.find('corpora/%s' % self.__name) 

            except LookupError as e: 

                try: root = nltk.data.find('corpora/%s' % zip_name) 

                except LookupError: raise e 

        # Load the corpus. 

        corpus = self.__reader_cls(root, *self.__args, **self.__kwargs) 

        # This is where the magic happens!  Transform ourselves into 

        # the corpus by modifying our own __dict__ and __class__ to 

        # match that of the corpus. 

        self.__dict__ = corpus.__dict__ 

        self.__class__ = corpus.__class__ 

    def __getattr__(self, attr): 

        self.__load() 

        # This looks circular, but its not, since __load() changes our 

        # __class__ to something new: 

        return getattr(self, attr) 

    def __repr__(self): 

        return '<%s in %r (not loaded yet)>' % ( 

            self.__reader_cls.__name__, '.../corpora/'+self.__name)