# Drop in replacement for python 2.7's OrderedDict, from...
# http://pypi.python.org/pypi/ordereddict
#
# Stem users should *not* rely upon this module. It will be removed when we
# drop support for python 2.6 and below.

# Copyright (c) 2009 Raymond Hettinger
#
# Permission is hereby granted, free of charge, to any person
# obtaining a copy of this software and associated documentation files
# (the "Software"), to deal in the Software without restriction,
# including without limitation the rights to use, copy, modify, merge,
# publish, distribute, sublicense, and/or sell copies of the Software,
# and to permit persons to whom the Software is furnished to do so,
# subject to the following conditions:
#
#     The above copyright notice and this permission notice shall be
#     included in all copies or substantial portions of the Software.
#
#     THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
#     EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
#     OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
#     NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
#     HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
#     WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
#     FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
#     OTHER DEALINGS IN THE SOFTWARE.

from UserDict import DictMixin


class OrderedDict(dict, DictMixin):
  def __init__(self, *args, **kwds):
    if len(args) > 1:
      raise TypeError('expected at most 1 arguments, got %d' % len(args))
    try:
      self.__end
    except AttributeError:
      self.clear()
    self.update(*args, **kwds)

  def clear(self):
    self.__end = end = []
    end += [None, end, end]         # sentinel node for doubly linked list
    self.__map = {}                 # key --> [key, prev, next]
    dict.clear(self)

  def __setitem__(self, key, value):
    if key not in self:
      end = self.__end
      curr = end[1]
      curr[2] = end[1] = self.__map[key] = [key, curr, end]
    dict.__setitem__(self, key, value)

  def __delitem__(self, key):
    dict.__delitem__(self, key)
    key, prev, next = self.__map.pop(key)
    prev[2] = next
    next[1] = prev

  def __iter__(self):
    end = self.__end
    curr = end[2]
    while curr is not end:
      yield curr[0]
      curr = curr[2]

  def __reversed__(self):
    end = self.__end
    curr = end[1]
    while curr is not end:
      yield curr[0]
      curr = curr[1]

  def popitem(self, last=True):
    if not self:
      raise KeyError('dictionary is empty')
    if last:
      key = reversed(self).next()
    else:
      key = iter(self).next()
    value = self.pop(key)
    return key, value

  def __reduce__(self):
    items = [[k, self[k]] for k in self]
    tmp = self.__map, self.__end
    del self.__map, self.__end
    inst_dict = vars(self).copy()
    self.__map, self.__end = tmp
    if inst_dict:
      return (self.__class__, (items,), inst_dict)
    return self.__class__, (items,)

  def keys(self):
    return list(self)

  setdefault = DictMixin.setdefault
  update = DictMixin.update
  pop = DictMixin.pop
  values = DictMixin.values
  items = DictMixin.items
  iterkeys = DictMixin.iterkeys
  itervalues = DictMixin.itervalues
  iteritems = DictMixin.iteritems

  def __repr__(self):
    if not self:
      return '%s()' % (self.__class__.__name__,)
    return '%s(%r)' % (self.__class__.__name__, self.items())

  def copy(self):
    return self.__class__(self)

  @classmethod
  def fromkeys(cls, iterable, value=None):
    d = cls()
    for key in iterable:
      d[key] = value
    return d

  def __eq__(self, other):
    if isinstance(other, OrderedDict):
      if len(self) != len(other):
        return False
      for p, q in zip(self.items(), other.items()):
        if p != q:
          return False
      return True
    return dict.__eq__(self, other)

  def __ne__(self, other):
    return not self == other