pokedex/util.py

   1 """Functions missing from Python 2.5"""
   2
   3 try:
   4     from itertools import permutations
   5 except ImportError:
   6     # From the itertools documentation
   7     def permutations(iterable, r=None):
   8         # permutations('ABCD', 2) --> AB AC AD BA BC BD CA CB CD DA DB DC
   9         # permutations(range(3)) --> 012 021 102 120 201 210
  10         pool = tuple(iterable)
  11         n = len(pool)
  12         r = n if r is None else r
  13         if r > n:
  14             return
  15         indices = range(n)
  16         cycles = range(n, n-r, -1)
  17         yield tuple(pool[i] for i in indices[:r])
  18         while n:
  19             for i in reversed(range(r)):
  20                 cycles[i] -= 1
  21                 if cycles[i] == 0:
  22                     indices[i:] = indices[i+1:] + indices[i:i+1]
  23                     cycles[i] = n - i
  24                 else:
  25                     j = cycles[i]
  26                     indices[i], indices[-j] = indices[-j], indices[i]
  27                     yield tuple(pool[i] for i in indices[:r])
  28                     break
  29             else:
  30                 return
  31
  32 try:
  33     from collections import namedtuple
  34 except ImportError:
  35     # http://code.activestate.com/recipes/500261-named-tuples/
  36     from operator import itemgetter as _itemgetter
  37     from keyword import iskeyword as _iskeyword
  38     import sys as _sys
  39
  40     def namedtuple(typename, field_names, verbose=False, rename=False):
  41         """Returns a new subclass of tuple with named fields.
  42
  43         >>> Point = namedtuple('Point', 'x y')
  44         >>> Point.__doc__                   # docstring for the new class
  45         'Point(x, y)'
  46         >>> p = Point(11, y=22)             # instantiate with positional args or keywords
  47         >>> p[0] + p[1]                     # indexable like a plain tuple
  48         33
  49         >>> x, y = p                        # unpack like a regular tuple
  50         >>> x, y
  51         (11, 22)
  52         >>> p.x + p.y                       # fields also accessable by name
  53         33
  54         >>> d = p._asdict()                 # convert to a dictionary
  55         >>> d['x']
  56         11
  57         >>> Point(**d)                      # convert from a dictionary
  58         Point(x=11, y=22)
  59         >>> p._replace(x=100)               # _replace() is like str.replace() but targets named fields
  60         Point(x=100, y=22)
  61
  62         """
  63
  64         # Parse and validate the field names.  Validation serves two purposes,
  65         # generating informative error messages and preventing template injection attacks.
  66         if isinstance(field_names, basestring):
  67             field_names = field_names.replace(',', ' ').split() # names separated by whitespace and/or commas
  68         field_names = tuple(map(str, field_names))
  69         if rename:
  70             names = list(field_names)
  71             seen = set()
  72             for i, name in enumerate(names):
  73                 if (not min(c.isalnum() or c=='_' for c in name) or _iskeyword(name)
  74                     or not name or name[0].isdigit() or name.startswith('_')
  75                     or name in seen):
  76                         names[i] = '_%d' % i
  77                 seen.add(name)
  78             field_names = tuple(names)
  79         for name in (typename,) + field_names:
  80             if not min(c.isalnum() or c=='_' for c in name):
  81                 raise ValueError('Type names and field names can only contain alphanumeric characters and underscores: %r' % name)
  82             if _iskeyword(name):
  83                 raise ValueError('Type names and field names cannot be a keyword: %r' % name)
  84             if name[0].isdigit():
  85                 raise ValueError('Type names and field names cannot start with a number: %r' % name)
  86         seen_names = set()
  87         for name in field_names:
  88             if name.startswith('_') and not rename:
  89                 raise ValueError('Field names cannot start with an underscore: %r' % name)
  90             if name in seen_names:
  91                 raise ValueError('Encountered duplicate field name: %r' % name)
  92             seen_names.add(name)
  93
  94         # Create and fill-in the class template
  95         numfields = len(field_names)
  96         argtxt = repr(field_names).replace("'", "")[1:-1]   # tuple repr without parens or quotes
  97         reprtxt = ', '.join('%s=%%r' % name for name in field_names)
  98         template = '''class %(typename)s(tuple):
  99             '%(typename)s(%(argtxt)s)' \n
 100             __slots__ = () \n
 101             _fields = %(field_names)r \n
 102             def __new__(_cls, %(argtxt)s):
 103                 return _tuple.__new__(_cls, (%(argtxt)s)) \n
 104             @classmethod
 105             def _make(cls, iterable, new=tuple.__new__, len=len):
 106                 'Make a new %(typename)s object from a sequence or iterable'
 107                 result = new(cls, iterable)
 108                 if len(result) != %(numfields)d:
 109                     raise TypeError('Expected %(numfields)d arguments, got %%d' %% len(result))
 110                 return result \n
 111             def __repr__(self):
 112                 return '%(typename)s(%(reprtxt)s)' %% self \n
 113             def _asdict(self):
 114                 'Return a new dict which maps field names to their values'
 115                 return dict(zip(self._fields, self)) \n
 116             def _replace(_self, **kwds):
 117                 'Return a new %(typename)s object replacing specified fields with new values'
 118                 result = _self._make(map(kwds.pop, %(field_names)r, _self))
 119                 if kwds:
 120                     raise ValueError('Got unexpected field names: %%r' %% kwds.keys())
 121                 return result \n
 122             def __getnewargs__(self):
 123                 return tuple(self) \n\n''' % locals()
 124         for i, name in enumerate(field_names):
 125             template += '            %s = _property(_itemgetter(%d))\n' % (name, i)
 126         if verbose:
 127             print template
 128
 129         # Execute the template string in a temporary namespace
 130         namespace = dict(_itemgetter=_itemgetter, __name__='namedtuple_%s' % typename,
 131                          _property=property, _tuple=tuple)
 132         try:
 133             exec template in namespace
 134         except SyntaxError, e:
 135             raise SyntaxError(e.message + ':\n' + template)
 136         result = namespace[typename]
 137
 138         # For pickling to work, the __module__ variable needs to be set to the frame
 139         # where the named tuple is created.  Bypass this step in enviroments where
 140         # sys._getframe is not defined (Jython for example) or sys._getframe is not
 141         # defined for arguments greater than 0 (IronPython).
 142         try:
 143             result.__module__ = _sys._getframe(1).f_globals.get('__name__', '__main__')
 144         except (AttributeError, ValueError):
 145             pass
 146
 147         return result
 148