cola/ordered_dict.py

   1 """Backport of OrderedDict() class
   2
   3 Runs on Python 2.4, 2.5, 2.6, 2.7, 3.x and pypy.
   4
   5 Passes Python2.7's test suite and incorporates all the latest updates.
   6 Copyright 2009 Raymond Hettinger, released under the MIT License.
   7 http://code.activestate.com/recipes/576693/
   8
   9 """
  10 from __future__ import absolute_import, division, unicode_literals
  11 try:
  12     # Python2's "thread" module must be tried first
  13     from thread import get_ident as _get_ident
  14 except ImportError:
  15     # Python2 also contains a "threading" module, but it does not
  16     # contain get_ident(), so this part would fail if it were done first.
  17     # get_ident() become available in the consolidated "threading" module
  18     # until Python3.
  19     from threading import get_ident as _get_ident
  20
  21
  22 class OrderedDict(dict):
  23     'Dictionary that remembers insertion order'
  24     # An inherited dict maps keys to values.
  25     # The inherited dict provides __getitem__, __len__, __contains__, and get.
  26     # The remaining methods are order-aware.
  27     # Big-O runtimes for all methods are the same as for regular dictionaries.
  28
  29     # The self.__map dictionary maps keys to links in a doubly linked list.
  30     # The circular doubly linked list starts and ends with a sentinel element.
  31     # The sentinel element never gets deleted (this simplifies the algorithm).
  32     # Each link is stored as a list of length three:  [PREV, NEXT, KEY].
  33
  34     # pylint: disable=super-init-not-called
  35     def __init__(self, *args, **kwds):
  36         '''Initialize an ordered dictionary.  Signature is the same as for
  37         regular dictionaries, but keyword arguments are not recommended
  38         because their insertion order is arbitrary.
  39
  40         '''
  41         if len(args) > 1:
  42             raise TypeError('expected at most 1 arguments, got %d' % len(args))
  43         try:
  44             self.__root
  45         except AttributeError:
  46             self.__root = root = []                     # sentinel node
  47             root[:] = [root, root, None]
  48             self.__map = {}
  49         self.__update(*args, **kwds)
  50
  51     def __setitem__(self, key, value, dict_setitem=dict.__setitem__):
  52         'od.__setitem__(i, y) <==> od[i]=y'
  53         # Setting a new item creates a new link which at the end of the linked
  54         # list, and the inherited dictionary is updated.
  55         if key not in self:
  56             root = self.__root
  57             last = root[0]
  58             last[1] = root[0] = self.__map[key] = [last, root, key]
  59         dict_setitem(self, key, value)
  60
  61     def __delitem__(self, key, dict_delitem=dict.__delitem__):
  62         'od.__delitem__(y) <==> del od[y]'
  63         # Deleting an existing item uses self.__map to find the link which is
  64         # then removed by updating the links in the predecessor and
  65         # successor nodes.
  66         dict_delitem(self, key)
  67         link_prev, link_next, key = self.__map.pop(key)
  68         link_prev[1] = link_next
  69         link_next[0] = link_prev
  70
  71     def __iter__(self):
  72         'od.__iter__() <==> iter(od)'
  73         root = self.__root
  74         curr = root[1]
  75         while curr is not root:
  76             yield curr[2]
  77             curr = curr[1]
  78
  79     def __reversed__(self):
  80         'od.__reversed__() <==> reversed(od)'
  81         root = self.__root
  82         curr = root[0]
  83         while curr is not root:
  84             yield curr[2]
  85             curr = curr[0]
  86
  87     def clear(self):
  88         'od.clear() -> None.  Remove all items from od.'
  89         try:
  90             for node in self.__map.values():
  91                 del node[:]
  92             root = self.__root
  93             root[:] = [root, root, None]
  94             self.__map.clear()
  95         except AttributeError:
  96             pass
  97         dict.clear(self)
  98
  99     def popitem(self, last=True):
 100         '''od.popitem() -> (k, v), return and remove a (key, value) pair.
 101         Pairs are returned in LIFO order if last is true or FIFO order if false.
 102
 103         '''
 104         if not self:
 105             raise KeyError('dictionary is empty')
 106         root = self.__root
 107         if last:
 108             link = root[0]
 109             link_prev = link[0]
 110             link_prev[1] = root
 111             root[0] = link_prev
 112         else:
 113             link = root[1]
 114             link_next = link[1]
 115             root[1] = link_next
 116             link_next[0] = root
 117         key = link[2]
 118         del self.__map[key]
 119         value = dict.pop(self, key)
 120         return key, value
 121
 122     # -- the following methods do not depend on the internal structure --
 123
 124     def keys(self):
 125         'od.keys() -> list of keys in od'
 126         return list(self)
 127
 128     def values(self):
 129         'od.values() -> list of values in od'
 130         return [self[key] for key in self]
 131
 132     def items(self):
 133         'od.items() -> list of (key, value) pairs in od'
 134         return [(key, self[key]) for key in self]
 135
 136     def iterkeys(self):
 137         'od.iterkeys() -> an iterator over the keys in od'
 138         return iter(self)
 139
 140     def itervalues(self):
 141         'od.itervalues -> an iterator over the values in od'
 142         for k in self:
 143             yield self[k]
 144
 145     def iteritems(self):
 146         'od.iteritems -> an iterator over the (key, value) items in od'
 147         for k in self:
 148             yield (k, self[k])
 149
 150     # pylint: disable=no-method-argument
 151     def update(*args, **kwds):
 152         '''od.update(E, **F) -> None.  Update od from dict/iterable E and F.
 153
 154         If E is a dict instance, does:           for k in E: od[k] = E[k]
 155         If E has a .keys() method, does:    for k in E.keys(): od[k] = E[k]
 156         Or if E is an iterable of items, does:   for k, v in E: od[k] = v
 157         In either case, this is followed by: for k, v in F.items(): od[k] = v
 158
 159         '''
 160         if len(args) > 2:
 161             raise TypeError('update() takes at most 2 positional '
 162                             'arguments (%d given)' % (len(args),))
 163         if not args:
 164             raise TypeError('update() takes at least 1 argument (0 given)')
 165         self = args[0]
 166         # Make progressively weaker assumptions about "other"
 167         other = ()
 168         if len(args) == 2:
 169             other = args[1]
 170         if isinstance(other, dict):
 171             for key in other:
 172                 self[key] = other[key]
 173         elif hasattr(other, 'keys'):
 174             for key in other.keys():
 175                 self[key] = other[key]
 176         else:
 177             for key, value in other:
 178                 self[key] = value
 179         for key, value in kwds.items():
 180             self[key] = value
 181
 182     # let subclasses override update without breaking __init__
 183     __update = update
 184
 185     __marker = object()
 186
 187     def pop(self, key, default=__marker):
 188         '''od.pop(k[,d]) -> v, remove specified key and return the value.
 189
 190         If key is not found, d is returned if given, otherwise
 191         KeyError is raised.
 192
 193         '''
 194         if key in self:
 195             result = self[key]
 196             del self[key]
 197             return result
 198         if default is self.__marker:
 199             raise KeyError(key)
 200         return default
 201
 202     def setdefault(self, key, default=None):
 203         'od.setdefault(k[,d]) -> od.get(k,d), also set od[k]=d if k not in od'
 204         if key in self:
 205             return self[key]
 206         self[key] = default
 207         return default
 208
 209     # pylint: disable=dangerous-default-value
 210     def __repr__(self, _repr_running={}):
 211         'od.__repr__() <==> repr(od)'
 212         call_key = id(self), _get_ident()
 213         if call_key in _repr_running:
 214             return '...'
 215         _repr_running[call_key] = 1
 216         try:
 217             if not self:
 218                 return '%s()' % (self.__class__.__name__,)
 219             items = list(self.items())
 220             return '%s(%r)' % (self.__class__.__name__, items)
 221         finally:
 222             del _repr_running[call_key]
 223
 224     def __reduce__(self):
 225         'Return state information for pickling'
 226         items = [[k, self[k]] for k in self]
 227         inst_dict = vars(self).copy()
 228         for k in vars(OrderedDict()):
 229             inst_dict.pop(k, None)
 230         if inst_dict:
 231             return (self.__class__, (items,), inst_dict)
 232         return self.__class__, (items,)
 233
 234     def copy(self):
 235         'od.copy() -> a shallow copy of od'
 236         return self.__class__(self)
 237
 238     @classmethod
 239     def fromkeys(cls, iterable, value=None):
 240         '''OD.fromkeys(S[, v]) -> New ordered dictionary with keys from S
 241         and values equal to v (which defaults to None).
 242
 243         '''
 244         d = cls()
 245         for key in iterable:
 246             d[key] = value
 247         return d
 248
 249     def __hash__(self):
 250         """Stable hash value"""
 251         # pylint: disable=dict-items-not-iterating
 252         return hash(frozenset(self.items()))
 253
 254     def __eq__(self, other):
 255         '''od.__eq__(y) <==> od==y.  Comparison to another OD is order-sensitive
 256         while comparison to a regular mapping is order-insensitive.
 257
 258         '''
 259         if isinstance(other, OrderedDict):
 260             return (len(self) == len(other)
 261                     and list(self.items()) == list(other.items()))
 262         return dict.__eq__(self, other)
 263
 264     def __ne__(self, other):
 265         return not self == other