Source Code for Module nltk.compat

  1  # Natural Language Toolkit: Compatibility Functions 
  2  # 
  3  # Copyright (C) 2001-2011 NLTK Project 
  4  # Author: Steven Bird <sb@csse.unimelb.edu.au> 
  5  #         Edward Loper <edloper@gradient.cis.upenn.edu> 
  6  # URL: <http://www.nltk.org/> 
  7  # For license information, see LICENSE.TXT 
  8   
  9  """ 
 10  Backwards compatibility with previous versions of Python. 
 11   
 12  This module provides backwards compatibility by defining 
 13  functions and classes that were not available in earlier versions of 
 14  Python.  Intented usage: 
 15   
 16      >>> from nltk.compat import * 
 17   
 18  Currently, NLTK requires Python 2.4 or later. 
 19  """ 
 20   
 21  ###################################################################### 
 22  # New in Python 2.5 
 23  ###################################################################### 
 24   
 25  # ElementTree 
 26   
 27  try: 
 28      from xml.etree import ElementTree 
 29  except ImportError: 
 30      from nltk.etree import ElementTree 
 31   
 32  # collections.defaultdict 
 33  # originally contributed by Yoav Goldberg <yoav.goldberg@gmail.com> 
 34  # new version by Jason Kirtland from Python cookbook. 
 35  # <http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/523034> 
 36  try: 
 37      from collections import defaultdict 
 38  except ImportError: 
 39 -    class defaultdict(dict): 
 40 -        def __init__(self, default_factory=None, *a, **kw): 
 41              if (default_factory is not None and 
 42                  not hasattr(default_factory, '__call__')): 
 43                  raise TypeError('first argument must be callable') 
 44              dict.__init__(self, *a, **kw) 
 45              self.default_factory = default_factory 
 46 -        def __getitem__(self, key): 
 47              try: 
 48                  return dict.__getitem__(self, key) 
 49              except KeyError: 
 50                  return self.__missing__(key) 
 51 -        def __missing__(self, key): 
 52              if self.default_factory is None: 
 53                  raise KeyError(key) 
 54              self[key] = value = self.default_factory() 
 55              return value 
 56 -        def __reduce__(self): 
 57              if self.default_factory is None: 
 58                  args = tuple() 
 59              else: 
 60                  args = self.default_factory, 
 61              return type(self), args, None, None, self.iteritems() 
 62 -        def copy(self): 
 63              return self.__copy__() 
 64 -        def __copy__(self): 
 65              return type(self)(self.default_factory, self) 
 66 -        def __deepcopy__(self, memo): 
 67              import copy 
 68              return type(self)(self.default_factory, 
 69                                copy.deepcopy(self.items())) 
 70 -        def __repr__(self): 
 71              return 'defaultdict(%s, %s)' % (self.default_factory, 
 72                                              dict.__repr__(self)) 
 73   
 74      # [XX] to make pickle happy in python 2.4: 
 75      import collections 
 76      collections.defaultdict = defaultdict 
 77   
 78  # all, any 
 79   
 80  try: 
 81      all([True]) 
 82      all = all 
 83  except NameError: 
 84 -    def all(iterable): 
 85          for i in iterable: 
 86              if not i: 
 87                  return False 
 88          else: 
 89              return True 
 90   
 91  try: 
 92      any([True]) 
 93      any = any 
 94  except NameError: 
 95 -    def any(iterable): 
 96          for i in iterable: 
 97              if i: 
 98                  return True 
 99          else: 
100              return False 
101   
102   
103  __all__ = ['ElementTree', 'defaultdict', 'all', 'any'] 
104