# -*- coding: utf-8 -*-

# Backport of OrderedDict() class that runs on Python 2.4, 2.5, 2.6, 2.7 and pypy.
# Passes Python2.7's test suite and incorporates all the latest updates.

try:
	from thread import get_ident as _get_ident
except ImportError:
	from dummy_thread import get_ident as _get_ident

try:
	from _abcoll import KeysView, ValuesView, ItemsView
except ImportError:
	pass


class OrderedDict(dict):
	'Dictionary that remembers insertion order'
	# An inherited dict maps keys to values.
	# The inherited dict provides __getitem__, __len__, __contains__, and get.
	# The remaining methods are order-aware.
	# Big-O running times for all methods are the same as for regular dictionaries.

	# The internal self.__map dictionary maps keys to links in a doubly linked list.
	# The circular doubly linked list starts and ends with a sentinel element.
	# The sentinel element never gets deleted (this simplifies the algorithm).
	# Each link is stored as a list of length three:  [PREV, NEXT, KEY].

	def __init__(self, *args, **kwds):
		'''Initialize an ordered dictionary.  Signature is the same as for
		regular dictionaries, but keyword arguments are not recommended
		because their insertion order is arbitrary.
		'''
		if len(args) > 1:
			raise TypeError('expected at most 1 arguments, got %d' % len(args))
		try:
			self.__root
		except AttributeError:
			self.__root = root = []					 # sentinel node
			root[:] = [root, root, None]
			self.__map = {}
		self.__update(*args, **kwds)

	def __setitem__(self, key, value, dict_setitem=dict.__setitem__):
		'od.__setitem__(i, y) <==> od[i]=y'
		# Setting a new item creates a new link which goes at the end of the linked
		# list, and the inherited dictionary is updated with the new key/value pair.
		if key not in self:
			root = self.__root
			last = root[0]
			last[1] = root[0] = self.__map[key] = [last, root, key]
		dict_setitem(self, key, value)

	def __delitem__(self, key, dict_delitem=dict.__delitem__):
		'od.__delitem__(y) <==> del od[y]'
		# Deleting an existing item uses self.__map to find the link which is
		# then removed by updating the links in the predecessor and successor nodes.
		dict_delitem(self, key)
		link_prev, link_next, key = self.__map.pop(key)
		link_prev[1] = link_next
		link_next[0] = link_prev

	def __iter__(self):
		'od.__iter__() <==> iter(od)'
		root = self.__root
		curr = root[1]
		while curr is not root:
			yield curr[2]
			curr = curr[1]

	def __reversed__(self):
		'od.__reversed__() <==> reversed(od)'
		root = self.__root
		curr = root[0]
		while curr is not root:
			yield curr[2]
			curr = curr[0]

	def clear(self):
		'od.clear() -> None.  Remove all items from od.'
		try:
			for node in self.__map.itervalues():
				del node[:]
			root = self.__root
			root[:] = [root, root, None]
			self.__map.clear()
		except AttributeError:
			pass
		dict.clear(self)

	def popitem(self, last=True):
		'''od.popitem() -> (k, v), return and remove a (key, value) pair.
		Pairs are returned in LIFO order if last is true or FIFO order if false.
		'''
		if not self:
			raise KeyError('dictionary is empty')
		root = self.__root
		if last:
			link = root[0]
			link_prev = link[0]
			link_prev[1] = root
			root[0] = link_prev
		else:
			link = root[1]
			link_next = link[1]
			root[1] = link_next
			link_next[0] = root
		key = link[2]
		del self.__map[key]
		value = dict.pop(self, key)
		return key, value

	# -- the following methods do not depend on the internal structure --

	def keys(self):
		'od.keys() -> list of keys in od'
		return list(self)

	def values(self):
		'od.values() -> list of values in od'
		return [self[key] for key in self]

	def items(self):
		'od.items() -> list of (key, value) pairs in od'
		return [(key, self[key]) for key in self]

	def iterkeys(self):
		'od.iterkeys() -> an iterator over the keys in od'
		return iter(self)

	def itervalues(self):
		'od.itervalues -> an iterator over the values in od'
		for k in self:
			yield self[k]

	def iteritems(self):
		'od.iteritems -> an iterator over the (key, value) items in od'
		for k in self:
			yield (k, self[k])

	def update(*args, **kwds):
		'''od.update(E, **F) -> None.  Update od from dict/iterable E and F.
		If E is a dict instance, does:		   for k in E: od[k] = E[k]
		If E has a .keys() method, does:		 for k in E.keys(): od[k] = E[k]
		Or if E is an iterable of items, does:   for k, v in E: od[k] = v
		In either case, this is followed by:	 for k, v in F.items(): od[k] = v
		'''
		if len(args) > 2:
			raise TypeError('update() takes at most 2 positional '
							'arguments (%d given)' % (len(args),))
		elif not args:
			raise TypeError('update() takes at least 1 argument (0 given)')
		self = args[0]
		# Make progressively weaker assumptions about "other"
		other = ()
		if len(args) == 2:
			other = args[1]
		if isinstance(other, dict):
			for key in other:
				self[key] = other[key]
		elif hasattr(other, 'keys'):
			for key in other.keys():
				self[key] = other[key]
		else:
			for key, value in other:
				self[key] = value
		for key, value in kwds.items():
			self[key] = value

	__update = update  # let subclasses override update without breaking __init__

	__marker = object()

	def pop(self, key, default=__marker):
		'''od.pop(k[,d]) -> v, remove specified key and return the corresponding value.
		If key is not found, d is returned if given, otherwise KeyError is raised.
		'''
		if key in self:
			result = self[key]
			del self[key]
			return result
		if default is self.__marker:
			raise KeyError(key)
		return default

	def setdefault(self, key, default=None):
		'od.setdefault(k[,d]) -> od.get(k,d), also set od[k]=d if k not in od'
		if key in self:
			return self[key]
		self[key] = default
		return default

	def __repr__(self, _repr_running={}):
		'od.__repr__() <==> repr(od)'
		call_key = id(self), _get_ident()
		if call_key in _repr_running:
			return '...'
		_repr_running[call_key] = 1
		try:
			if not self:
				return '%s()' % (self.__class__.__name__,)
			return '%s(%r)' % (self.__class__.__name__, self.items())
		finally:
			del _repr_running[call_key]

	def __reduce__(self):
		'Return state information for pickling'
		items = [[k, self[k]] for k in self]
		inst_dict = vars(self).copy()
		for k in vars(OrderedDict()):
			inst_dict.pop(k, None)
		if inst_dict:
			return (self.__class__, (items,), inst_dict)
		return self.__class__, (items,)

	def copy(self):
		'od.copy() -> a shallow copy of od'
		return self.__class__(self)

	@classmethod
	def fromkeys(cls, iterable, value=None):
		'''OD.fromkeys(S[, v]) -> New ordered dictionary with keys from S
		and values equal to v (which defaults to None).
		'''
		d = cls()
		for key in iterable:
			d[key] = value
		return d

	def __eq__(self, other):
		'''od.__eq__(y) <==> od==y.  Comparison to another OD is order-sensitive
		while comparison to a regular mapping is order-insensitive.
		'''
		if isinstance(other, OrderedDict):
			return len(self) == len(other) and self.items() == other.items()
		return dict.__eq__(self, other)

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

	# -- the following methods are only used in Python 2.7 --

	def viewkeys(self):
		"od.viewkeys() -> a set-like object providing a view on od's keys"
		return KeysView(self)

	def viewvalues(self):
		"od.viewvalues() -> an object providing a view on od's values"
		return ValuesView(self)

	def viewitems(self):
		"od.viewitems() -> a set-like object providing a view on od's items"
		return ItemsView(self)
