PEP 372: OrderedDict()
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Raymond Hettinger
parent
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commit
2d32f63ec9
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@ -14,7 +14,7 @@
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__name__ = '<doctest>'
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This module implements high-performance container datatypes. Currently,
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there are three datatypes, :class:`Counter`, :class:`deque` and
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there are four datatypes, :class:`Counter`, :class:`deque`, :class:`OrderedDict` and
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:class:`defaultdict`, and one datatype factory function, :func:`namedtuple`.
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The specialized containers provided in this module provide alternatives
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@ -806,6 +806,33 @@ and more efficient to use a simple class declaration:
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adapted for Python 2.4.
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:class:`OrderedDict` objects
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----------------------------
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Ordered dictionaries are just like regular dictionaries but they remember the
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order that items were inserted. When iterating over an ordered dictionary,
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the items are returned in the order their keys were first added.
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.. class:: OrderedDict([items])
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Return an instance of a dict subclass, supporting the usual :class:`dict`
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methods. An *OrderedDict* is a dict that remembers the order that keys
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were first inserted. If a new entry overwrites an existing entry, the
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original insertion position is left unchanged. Deleting an entry and
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reinserting it will move it to the end.
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.. versionadded:: 2.7
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The :meth:`popitem` method for ordered dictionaries returns and removes the
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last added entry. The key/value pairs are returned in LIFO order.
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Equality tests between :class:`OrderedDict` objects are order-sensitive
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and are implemented as ``list(od1.items())==list(od2.items())``.
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Equality tests between :class:`OrderedDict` objects and other
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:class:`Mapping` objects are order-insensitive like regular dictionaries.
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This allows :class:`OrderedDict` objects to be substituted anywhere a
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regular dictionary is used.
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:class:`UserDict` objects
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-------------------------
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@ -1,5 +1,5 @@
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__all__ = ['deque', 'defaultdict', 'namedtuple', 'UserDict', 'UserList',
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'UserString', 'Counter']
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'UserString', 'Counter', 'OrderedDict']
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# For bootstrapping reasons, the collection ABCs are defined in _abcoll.py.
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# They should however be considered an integral part of collections.py.
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from _abcoll import *
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@ -11,7 +11,81 @@ from operator import itemgetter as _itemgetter
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from keyword import iskeyword as _iskeyword
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import sys as _sys
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import heapq as _heapq
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from itertools import repeat as _repeat, chain as _chain, starmap as _starmap
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from itertools import repeat as _repeat, chain as _chain, starmap as _starmap, \
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zip_longest as _zip_longest
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################################################################################
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### OrderedDict
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################################################################################
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class OrderedDict(dict, MutableMapping):
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def __init__(self, *args, **kwds):
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if len(args) > 1:
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raise TypeError('expected at most 1 arguments, got %d' % len(args))
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if not hasattr(self, '_keys'):
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self._keys = []
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self.update(*args, **kwds)
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def clear(self):
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del self._keys[:]
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dict.clear(self)
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def __setitem__(self, key, value):
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if key not in self:
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self._keys.append(key)
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dict.__setitem__(self, key, value)
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def __delitem__(self, key):
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dict.__delitem__(self, key)
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self._keys.remove(key)
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def __iter__(self):
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return iter(self._keys)
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def __reversed__(self):
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return reversed(self._keys)
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def popitem(self):
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if not self:
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raise KeyError('dictionary is empty')
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key = self._keys.pop()
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value = dict.pop(self, key)
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return key, value
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def __reduce__(self):
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items = [[k, self[k]] for k in self]
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inst_dict = vars(self).copy()
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inst_dict.pop('_keys', None)
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return (self.__class__, (items,), inst_dict)
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setdefault = MutableMapping.setdefault
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update = MutableMapping.update
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pop = MutableMapping.pop
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keys = MutableMapping.keys
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values = MutableMapping.values
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items = MutableMapping.items
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def __repr__(self):
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if not self:
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return '%s()' % (self.__class__.__name__,)
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return '%s(%r)' % (self.__class__.__name__, list(self.items()))
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def copy(self):
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return self.__class__(self)
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@classmethod
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def fromkeys(cls, iterable, value=None):
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d = cls()
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for key in iterable:
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d[key] = value
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return d
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def __eq__(self, other):
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if isinstance(other, OrderedDict):
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return all(p==q for p, q in _zip_longest(self.items(), other.items()))
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return dict.__eq__(self, other)
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################################################################################
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@ -1,10 +1,12 @@
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"""Unit tests for collections.py."""
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import unittest, doctest
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import inspect
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from test import support
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from collections import namedtuple, Counter, Mapping
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from collections import namedtuple, Counter, OrderedDict
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from test import mapping_tests
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import pickle, copy
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from random import randrange
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from random import randrange, shuffle
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import operator
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from collections import Hashable, Iterable, Iterator
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from collections import Sized, Container, Callable
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@ -571,12 +573,201 @@ class TestCounter(unittest.TestCase):
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set_result = setop(set(p.elements()), set(q.elements()))
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self.assertEqual(counter_result, dict.fromkeys(set_result, 1))
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class TestOrderedDict(unittest.TestCase):
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def test_init(self):
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with self.assertRaises(TypeError):
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OrderedDict([('a', 1), ('b', 2)], None) # too many args
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pairs = [('a', 1), ('b', 2), ('c', 3), ('d', 4), ('e', 5)]
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self.assertEqual(sorted(OrderedDict(dict(pairs)).items()), pairs) # dict input
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self.assertEqual(sorted(OrderedDict(**dict(pairs)).items()), pairs) # kwds input
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self.assertEqual(list(OrderedDict(pairs).items()), pairs) # pairs input
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self.assertEqual(list(OrderedDict([('a', 1), ('b', 2), ('c', 9), ('d', 4)],
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c=3, e=5).items()), pairs) # mixed input
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# make sure no positional args conflict with possible kwdargs
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self.assertEqual(inspect.getargspec(OrderedDict.__dict__['__init__']).args,
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['self'])
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# Make sure that direct calls to __init__ do not clear previous contents
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d = OrderedDict([('a', 1), ('b', 2), ('c', 3), ('d', 44), ('e', 55)])
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d.__init__([('e', 5), ('f', 6)], g=7, d=4)
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self.assertEqual(list(d.items()),
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[('a', 1), ('b', 2), ('c', 3), ('d', 4), ('e', 5), ('f', 6), ('g', 7)])
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def test_update(self):
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with self.assertRaises(TypeError):
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OrderedDict().update([('a', 1), ('b', 2)], None) # too many args
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pairs = [('a', 1), ('b', 2), ('c', 3), ('d', 4), ('e', 5)]
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od = OrderedDict()
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od.update(dict(pairs))
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self.assertEqual(sorted(od.items()), pairs) # dict input
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od = OrderedDict()
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od.update(**dict(pairs))
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self.assertEqual(sorted(od.items()), pairs) # kwds input
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od = OrderedDict()
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od.update(pairs)
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self.assertEqual(list(od.items()), pairs) # pairs input
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od = OrderedDict()
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od.update([('a', 1), ('b', 2), ('c', 9), ('d', 4)], c=3, e=5)
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self.assertEqual(list(od.items()), pairs) # mixed input
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# Make sure that direct calls to update do not clear previous contents
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# add that updates items are not moved to the end
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d = OrderedDict([('a', 1), ('b', 2), ('c', 3), ('d', 44), ('e', 55)])
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d.update([('e', 5), ('f', 6)], g=7, d=4)
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self.assertEqual(list(d.items()),
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[('a', 1), ('b', 2), ('c', 3), ('d', 4), ('e', 5), ('f', 6), ('g', 7)])
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def test_clear(self):
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pairs = [('c', 1), ('b', 2), ('a', 3), ('d', 4), ('e', 5), ('f', 6)]
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shuffle(pairs)
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od = OrderedDict(pairs)
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self.assertEqual(len(od), len(pairs))
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od.clear()
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self.assertEqual(len(od), 0)
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def test_delitem(self):
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pairs = [('c', 1), ('b', 2), ('a', 3), ('d', 4), ('e', 5), ('f', 6)]
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od = OrderedDict(pairs)
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del od['a']
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self.assert_('a' not in od)
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with self.assertRaises(KeyError):
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del od['a']
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self.assertEqual(list(od.items()), pairs[:2] + pairs[3:])
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def test_setitem(self):
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od = OrderedDict([('d', 1), ('b', 2), ('c', 3), ('a', 4), ('e', 5)])
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od['c'] = 10 # existing element
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od['f'] = 20 # new element
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self.assertEqual(list(od.items()),
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[('d', 1), ('b', 2), ('c', 10), ('a', 4), ('e', 5), ('f', 20)])
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def test_iterators(self):
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pairs = [('c', 1), ('b', 2), ('a', 3), ('d', 4), ('e', 5), ('f', 6)]
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shuffle(pairs)
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od = OrderedDict(pairs)
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self.assertEqual(list(od), [t[0] for t in pairs])
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self.assertEqual(list(od.keys()), [t[0] for t in pairs])
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self.assertEqual(list(od.values()), [t[1] for t in pairs])
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self.assertEqual(list(od.items()), pairs)
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self.assertEqual(list(reversed(od)),
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[t[0] for t in reversed(pairs)])
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def test_popitem(self):
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pairs = [('c', 1), ('b', 2), ('a', 3), ('d', 4), ('e', 5), ('f', 6)]
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shuffle(pairs)
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od = OrderedDict(pairs)
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while pairs:
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self.assertEqual(od.popitem(), pairs.pop())
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with self.assertRaises(KeyError):
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od.popitem()
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self.assertEqual(len(od), 0)
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def test_pop(self):
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pairs = [('c', 1), ('b', 2), ('a', 3), ('d', 4), ('e', 5), ('f', 6)]
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shuffle(pairs)
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od = OrderedDict(pairs)
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shuffle(pairs)
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while pairs:
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k, v = pairs.pop()
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self.assertEqual(od.pop(k), v)
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with self.assertRaises(KeyError):
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od.pop('xyz')
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self.assertEqual(len(od), 0)
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self.assertEqual(od.pop(k, 12345), 12345)
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def test_equality(self):
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pairs = [('c', 1), ('b', 2), ('a', 3), ('d', 4), ('e', 5), ('f', 6)]
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shuffle(pairs)
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od1 = OrderedDict(pairs)
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od2 = OrderedDict(pairs)
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self.assertEqual(od1, od2) # same order implies equality
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pairs = pairs[2:] + pairs[:2]
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od2 = OrderedDict(pairs)
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self.assertNotEqual(od1, od2) # different order implies inequality
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# comparison to regular dict is not order sensitive
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self.assertEqual(od1, dict(od2))
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self.assertEqual(dict(od2), od1)
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# different length implied inequality
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self.assertNotEqual(od1, OrderedDict(pairs[:-1]))
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def test_copying(self):
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# Check that ordered dicts are copyable, deepcopyable, picklable,
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# and have a repr/eval round-trip
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pairs = [('c', 1), ('b', 2), ('a', 3), ('d', 4), ('e', 5), ('f', 6)]
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od = OrderedDict(pairs)
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update_test = OrderedDict()
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update_test.update(od)
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for i, dup in enumerate([
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od.copy(),
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copy.copy(od),
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copy.deepcopy(od),
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pickle.loads(pickle.dumps(od, 0)),
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pickle.loads(pickle.dumps(od, 1)),
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pickle.loads(pickle.dumps(od, 2)),
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pickle.loads(pickle.dumps(od, 3)),
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pickle.loads(pickle.dumps(od, -1)),
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eval(repr(od)),
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update_test,
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OrderedDict(od),
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]):
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self.assert_(dup is not od)
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self.assertEquals(dup, od)
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self.assertEquals(list(dup.items()), list(od.items()))
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self.assertEquals(len(dup), len(od))
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self.assertEquals(type(dup), type(od))
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def test_repr(self):
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od = OrderedDict([('c', 1), ('b', 2), ('a', 3), ('d', 4), ('e', 5), ('f', 6)])
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self.assertEqual(repr(od),
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"OrderedDict([('c', 1), ('b', 2), ('a', 3), ('d', 4), ('e', 5), ('f', 6)])")
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self.assertEqual(eval(repr(od)), od)
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self.assertEqual(repr(OrderedDict()), "OrderedDict()")
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def test_setdefault(self):
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pairs = [('c', 1), ('b', 2), ('a', 3), ('d', 4), ('e', 5), ('f', 6)]
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shuffle(pairs)
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od = OrderedDict(pairs)
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pair_order = list(od.items())
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self.assertEqual(od.setdefault('a', 10), 3)
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# make sure order didn't change
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self.assertEqual(list(od.items()), pair_order)
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self.assertEqual(od.setdefault('x', 10), 10)
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# make sure 'x' is added to the end
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self.assertEqual(list(od.items())[-1], ('x', 10))
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def test_reinsert(self):
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# Given insert a, insert b, delete a, re-insert a,
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# verify that a is now later than b.
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od = OrderedDict()
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od['a'] = 1
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od['b'] = 2
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del od['a']
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od['a'] = 1
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self.assertEqual(list(od.items()), [('b', 2), ('a', 1)])
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class GeneralMappingTests(mapping_tests.BasicTestMappingProtocol):
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type2test = OrderedDict
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class MyOrderedDict(OrderedDict):
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pass
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class SubclassMappingTests(mapping_tests.BasicTestMappingProtocol):
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type2test = MyOrderedDict
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import doctest, collections
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def test_main(verbose=None):
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NamedTupleDocs = doctest.DocTestSuite(module=collections)
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test_classes = [TestNamedTuple, NamedTupleDocs, TestOneTrickPonyABCs,
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TestCollectionABCs, TestCounter]
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TestCollectionABCs, TestCounter,
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TestOrderedDict, GeneralMappingTests, SubclassMappingTests]
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support.run_unittest(*test_classes)
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support.run_doctest(collections, verbose)
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