Class OrderedDict

Create a new ordered dictionary. Cannot init from a normal dict,
nor from kwargs, since items order is undefined in those cases.

If the ``strict`` keyword argument is ``True`` (``False`` is the
default) then when doing slice assignment - the ``OrderedDict`` you are
assigning from *must not* contain any keys in the remaining dict.

>>> OrderedDict()
OrderedDict([])
>>> OrderedDict({1: 1})
Traceback (most recent call last):
TypeError: undefined order, cannot get items from dict
>>> d = OrderedDict(((1, 3), (3, 2), (2, 1)))
>>> d
OrderedDict([(1, 3), (3, 2), (2, 1)])
>>> OrderedDict(d)
OrderedDict([(1, 3), (3, 2), (2, 1)])

Returns:

new empty dictionary

Overrides: object.__init__

>>> d = OrderedDict(((1, 3), (3, 2), (2, 1)))
>>> del d[3]
>>> d
OrderedDict([(1, 3), (2, 1)])
>>> del d[3]
Traceback (most recent call last):
KeyError: 3
>>> d[3] = 2
>>> d
OrderedDict([(1, 3), (2, 1), (3, 2)])
>>> del d[0:1]
>>> d
OrderedDict([(2, 1), (3, 2)])

Overrides: dict.__delitem__

>>> d = OrderedDict(((1, 3), (3, 2), (2, 1)))
>>> d == OrderedDict(d)
1
>>> d == OrderedDict(((1, 3), (2, 1), (3, 2)))
0
>>> d == OrderedDict(((1, 0), (3, 2), (2, 1)))
0
>>> d == OrderedDict(((0, 3), (3, 2), (2, 1)))
0
>>> d == dict(d)
Traceback (most recent call last):
TypeError: Equality undefined for OrderedDicts and dictionaries
>>> d == False
0

Overrides: dict.__eq__

>>> d = OrderedDict(((1, 3), (3, 2), (2, 1)))
>>> c = OrderedDict(((0, 3), (3, 2), (2, 1)))
>>> c < d
1
>>> d < c
0
>>> d < dict(c)
Traceback (most recent call last):
TypeError: Can only compare with other OrderedDicts

Overrides: dict.__lt__

>>> d = OrderedDict(((1, 3), (3, 2), (2, 1)))
>>> c = OrderedDict(((0, 3), (3, 2), (2, 1)))
>>> e = OrderedDict(d)
>>> c <= d
1
>>> d <= c
0
>>> d <= dict(c)
Traceback (most recent call last):
TypeError: Can only compare with other OrderedDicts
>>> d <= e
1

Overrides: dict.__le__

>>> d = OrderedDict(((1, 3), (3, 2), (2, 1)))
>>> d != OrderedDict(d)
0
>>> d != OrderedDict(((1, 3), (2, 1), (3, 2)))
1
>>> d != OrderedDict(((1, 0), (3, 2), (2, 1)))
1
>>> d == OrderedDict(((0, 3), (3, 2), (2, 1)))
0
>>> d != dict(d)
Traceback (most recent call last):
TypeError: Inequality undefined for OrderedDicts and dictionaries
>>> d != False
1

Overrides: dict.__ne__

>>> d = OrderedDict(((1, 3), (3, 2), (2, 1)))
>>> c = OrderedDict(((0, 3), (3, 2), (2, 1)))
>>> d > c
1
>>> c > d
0
>>> d > dict(c)
Traceback (most recent call last):
TypeError: Can only compare with other OrderedDicts

Overrides: dict.__gt__

>>> d = OrderedDict(((1, 3), (3, 2), (2, 1)))
>>> c = OrderedDict(((0, 3), (3, 2), (2, 1)))
>>> e = OrderedDict(d)
>>> c >= d
0
>>> d >= c
1
>>> d >= dict(c)
Traceback (most recent call last):
TypeError: Can only compare with other OrderedDicts
>>> e >= d
1

Overrides: dict.__ge__

Used for __repr__ and __str__

>>> r1 = repr(OrderedDict((('a', 'b'), ('c', 'd'), ('e', 'f'))))
>>> r1
"OrderedDict([('a', 'b'), ('c', 'd'), ('e', 'f')])"
>>> r2 = repr(OrderedDict((('a', 'b'), ('e', 'f'), ('c', 'd'))))
>>> r2
"OrderedDict([('a', 'b'), ('e', 'f'), ('c', 'd')])"
>>> r1 == str(OrderedDict((('a', 'b'), ('c', 'd'), ('e', 'f'))))
1
>>> r2 == str(OrderedDict((('a', 'b'), ('e', 'f'), ('c', 'd'))))
1

Overrides: object.__repr__

Allows slice assignment, so long as the slice is an OrderedDict
>>> d = OrderedDict()
>>> d['a'] = 'b'
>>> d['b'] = 'a'
>>> d[3] = 12
>>> d
OrderedDict([('a', 'b'), ('b', 'a'), (3, 12)])
>>> d[:] = OrderedDict(((1, 2), (2, 3), (3, 4)))
>>> d
OrderedDict([(1, 2), (2, 3), (3, 4)])
>>> d[::2] = OrderedDict(((7, 8), (9, 10)))
>>> d
OrderedDict([(7, 8), (2, 3), (9, 10)])
>>> d = OrderedDict(((0, 1), (1, 2), (2, 3), (3, 4)))
>>> d[1:3] = OrderedDict(((1, 2), (5, 6), (7, 8)))
>>> d
OrderedDict([(0, 1), (1, 2), (5, 6), (7, 8), (3, 4)])
>>> d = OrderedDict(((0, 1), (1, 2), (2, 3), (3, 4)), strict=True)
>>> d[1:3] = OrderedDict(((1, 2), (5, 6), (7, 8)))
>>> d
OrderedDict([(0, 1), (1, 2), (5, 6), (7, 8), (3, 4)])

>>> a = OrderedDict(((0, 1), (1, 2), (2, 3)), strict=True)
>>> a[3] = 4
>>> a
OrderedDict([(0, 1), (1, 2), (2, 3), (3, 4)])
>>> a[::1] = OrderedDict([(0, 1), (1, 2), (2, 3), (3, 4)])
>>> a
OrderedDict([(0, 1), (1, 2), (2, 3), (3, 4)])
>>> a[:2] = OrderedDict([(0, 1), (1, 2), (2, 3), (3, 4), (4, 5)])
Traceback (most recent call last):
ValueError: slice assignment must be from unique keys
>>> a = OrderedDict(((0, 1), (1, 2), (2, 3)))
>>> a[3] = 4
>>> a
OrderedDict([(0, 1), (1, 2), (2, 3), (3, 4)])
>>> a[::1] = OrderedDict([(0, 1), (1, 2), (2, 3), (3, 4)])
>>> a
OrderedDict([(0, 1), (1, 2), (2, 3), (3, 4)])
>>> a[:2] = OrderedDict([(0, 1), (1, 2), (2, 3), (3, 4)])
>>> a
OrderedDict([(0, 1), (1, 2), (2, 3), (3, 4)])
>>> a[::-1] = OrderedDict([(0, 1), (1, 2), (2, 3), (3, 4)])
>>> a
OrderedDict([(3, 4), (2, 3), (1, 2), (0, 1)])

>>> d = OrderedDict([(0, 1), (1, 2), (2, 3), (3, 4)])
>>> d[:1] = 3
Traceback (most recent call last):
TypeError: slice assignment requires an OrderedDict

>>> d = OrderedDict([(0, 1), (1, 2), (2, 3), (3, 4)])
>>> d[:1] = OrderedDict([(9, 8)])
>>> d
OrderedDict([(9, 8), (1, 2), (2, 3), (3, 4)])

Overrides: dict.__setitem__

Allows slicing. Returns an OrderedDict if you slice.
>>> b = OrderedDict([(7, 0), (6, 1), (5, 2), (4, 3), (3, 4), (2, 5), (1, 6)])
>>> b[::-1]
OrderedDict([(1, 6), (2, 5), (3, 4), (4, 3), (5, 2), (6, 1), (7, 0)])
>>> b[2:5]
OrderedDict([(5, 2), (4, 3), (3, 4)])
>>> type(b[2:4])
<class '__main__.OrderedDict'>

Overrides: dict.__getitem__

Used for __repr__ and __str__

>>> r1 = repr(OrderedDict((('a', 'b'), ('c', 'd'), ('e', 'f'))))
>>> r1
"OrderedDict([('a', 'b'), ('c', 'd'), ('e', 'f')])"
>>> r2 = repr(OrderedDict((('a', 'b'), ('e', 'f'), ('c', 'd'))))
>>> r2
"OrderedDict([('a', 'b'), ('e', 'f'), ('c', 'd')])"
>>> r1 == str(OrderedDict((('a', 'b'), ('c', 'd'), ('e', 'f'))))
1
>>> r2 == str(OrderedDict((('a', 'b'), ('e', 'f'), ('c', 'd'))))
1

Overrides: object.__str__

Implemented so that accesses to ``sequence`` raise a warning and are
diverted to the new ``setkeys`` method.

Overrides: object.__setattr__

Implemented so that access to ``sequence`` raises a warning.

>>> d = OrderedDict()
>>> d.sequence
[]

To allow deepcopy to work with OrderedDict.

>>> from copy import deepcopy
>>> a = OrderedDict([(1, 1), (2, 2), (3, 3)])
>>> a['test'] = {}
>>> b = deepcopy(a)
>>> b == a
1
>>> b is a
0
>>> a['test'] is b['test']
0

>>> OrderedDict(((1, 3), (3, 2), (2, 1))).copy()
OrderedDict([(1, 3), (3, 2), (2, 1)])

Returns: a shallow copy of D

Overrides: dict.copy

``items`` returns a list of tuples representing all the 
``(key, value)`` pairs in the dictionary.

>>> d = OrderedDict(((1, 3), (3, 2), (2, 1)))
>>> d.items()
[(1, 3), (3, 2), (2, 1)]
>>> d.clear()
>>> d.items()
[]

Returns: list of D's (key, value) pairs, as 2-tuples

Overrides: dict.items

Return a list of keys in the ``OrderedDict``.

>>> d = OrderedDict(((1, 3), (3, 2), (2, 1)))
>>> d.keys()
[1, 3, 2]

Returns: list of D's keys

Overrides: dict.keys

Return a list of all the values in the OrderedDict.

Optionally you can pass in a list of values, which will replace the
current list. The value list must be the same len as the OrderedDict.

>>> d = OrderedDict(((1, 3), (3, 2), (2, 1)))
>>> d.values()
[3, 2, 1]

Returns: list of D's values

Overrides: dict.values

>>> ii = OrderedDict(((1, 3), (3, 2), (2, 1))).iteritems()
>>> ii.next()
(1, 3)
>>> ii.next()
(3, 2)
>>> ii.next()
(2, 1)
>>> ii.next()
Traceback (most recent call last):
StopIteration

Returns: an iterator over the (key, value) items of D

Overrides: dict.iteritems

>>> ii = OrderedDict(((1, 3), (3, 2), (2, 1))).iterkeys()
>>> ii.next()
1
>>> ii.next()
3
>>> ii.next()
2
>>> ii.next()
Traceback (most recent call last):
StopIteration

Returns: an iterator over the keys of D

Overrides: dict.iterkeys

>>> ii = OrderedDict(((1, 3), (3, 2), (2, 1))).iterkeys()
>>> ii.next()
1
>>> ii.next()
3
>>> ii.next()
2
>>> ii.next()
Traceback (most recent call last):
StopIteration

Returns: an iterator over the keys of D

Overrides: dict.__iter__

>>> iv = OrderedDict(((1, 3), (3, 2), (2, 1))).itervalues()
>>> iv.next()
3
>>> iv.next()
2
>>> iv.next()
1
>>> iv.next()
Traceback (most recent call last):
StopIteration

Returns: an iterator over the values of D

Overrides: dict.itervalues

>>> d = OrderedDict(((1, 3), (3, 2), (2, 1)))
>>> d.clear()
>>> d
OrderedDict([])

Returns: None

Overrides: dict.clear

No dict.pop in Python 2.2, gotta reimplement it

>>> d = OrderedDict(((1, 3), (3, 2), (2, 1)))
>>> d.pop(3)
2
>>> d
OrderedDict([(1, 3), (2, 1)])
>>> d.pop(4)
Traceback (most recent call last):
KeyError: 4
>>> d.pop(4, 0)
0
>>> d.pop(4, 0, 1)
Traceback (most recent call last):
TypeError: pop expected at most 2 arguments, got 3

Returns: v, remove specified key and return the corresponding value

Overrides: dict.pop

Delete and return an item specified by index, not a random one as in
dict. The index is -1 by default (the last item).

>>> d = OrderedDict(((1, 3), (3, 2), (2, 1)))
>>> d.popitem()
(2, 1)
>>> d
OrderedDict([(1, 3), (3, 2)])
>>> d.popitem(0)
(1, 3)
>>> OrderedDict().popitem()
Traceback (most recent call last):
KeyError: 'popitem(): dictionary is empty'
>>> d.popitem(2)
Traceback (most recent call last):
IndexError: popitem(): index 2 not valid

Returns: (k, v), remove and return some (key, value) pair as a

Overrides: dict.popitem

>>> d = OrderedDict(((1, 3), (3, 2), (2, 1)))
>>> d.setdefault(1)
3
>>> d.setdefault(4) is None
1
>>> d
OrderedDict([(1, 3), (3, 2), (2, 1), (4, None)])
>>> d.setdefault(5, 0)
0
>>> d
OrderedDict([(1, 3), (3, 2), (2, 1), (4, None), (5, 0)])

Returns: D.get(k,d), also set D[k]=d if k not in D

Overrides: dict.setdefault

Update from another OrderedDict or sequence of (key, value) pairs

>>> d = OrderedDict()
>>> d.update(OrderedDict(((1, 3), (3, 2), (2, 1))))
>>> d
OrderedDict([(1, 3), (3, 2), (2, 1)])
>>> d.update({4: 4})
Traceback (most recent call last):
TypeError: undefined order, cannot get items from dict
>>> d.update((4, 4))
Traceback (most recent call last):
TypeError: cannot convert dictionary update sequence element #0 to a sequence

Returns: None

Overrides: dict.update

This method allows you to set the items in the dict.

It takes a list of tuples - of the same sort returned by the ``items``
method.

>>> d = OrderedDict()
>>> d.setitems(((3, 1), (2, 3), (1, 2)))
>>> d
OrderedDict([(3, 1), (2, 3), (1, 2)])

``setkeys`` all ows you to pass in a new list of keys which will
replace the current set. This must contain the same set of keys, but
need not be in the same order.

If you pass in new keys that don't match, a ``KeyError`` will be
raised.

>>> d = OrderedDict(((1, 3), (3, 2), (2, 1)))
>>> d.keys()
[1, 3, 2]
>>> d.setkeys((1, 2, 3))
>>> d
OrderedDict([(1, 3), (2, 1), (3, 2)])
>>> d.setkeys(['a', 'b', 'c'])
Traceback (most recent call last):
KeyError: 'Keylist is not the same as current keylist.'

You can pass in a list of values, which will replace the
current list. The value list must be the same len as the OrderedDict.

(Or a ``ValueError`` is raised.)

>>> d = OrderedDict(((1, 3), (3, 2), (2, 1)))
>>> d.setvalues((1, 2, 3))
>>> d
OrderedDict([(1, 1), (3, 2), (2, 3)])
>>> d.setvalues([6])
Traceback (most recent call last):
ValueError: Value list is not the same length as the OrderedDict.

Return the position of the specified key in the OrderedDict.

>>> d = OrderedDict(((1, 3), (3, 2), (2, 1)))
>>> d.index(3)
1
>>> d.index(4)
Traceback (most recent call last):
ValueError: list.index(x): x not in list

Takes ``index``, ``key``, and ``value`` as arguments.

Sets ``key`` to ``value``, so that ``key`` is at position ``index`` in
the OrderedDict.

>>> d = OrderedDict(((1, 3), (3, 2), (2, 1)))
>>> d.insert(0, 4, 0)
>>> d
OrderedDict([(4, 0), (1, 3), (3, 2), (2, 1)])
>>> d.insert(0, 2, 1)
>>> d
OrderedDict([(2, 1), (4, 0), (1, 3), (3, 2)])
>>> d.insert(8, 8, 1)
>>> d
OrderedDict([(2, 1), (4, 0), (1, 3), (3, 2), (8, 1)])

Reverse the order of the OrderedDict.

>>> d = OrderedDict(((1, 3), (3, 2), (2, 1)))
>>> d.reverse()
>>> d
OrderedDict([(2, 1), (3, 2), (1, 3)])

Sort the key order in the OrderedDict.

This method takes the same arguments as the ``list.sort`` method on
your version of Python.

>>> d = OrderedDict(((4, 1), (2, 2), (3, 3), (1, 4)))
>>> d.sort()
>>> d
OrderedDict([(1, 4), (2, 2), (3, 3), (4, 1)])