65 lines
1.5 KiB
Python
65 lines
1.5 KiB
Python
import collections
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import operator
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import functools
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import sys
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try:
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from collections import OrderedDict
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except ImportError: # python < 2.7
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OrderedDict = NotImplemented
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iteritems = getattr(dict, 'iteritems', dict.items) # py2-3 compatibility
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class frozendict(collections.Mapping):
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"""
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An immutable wrapper around dictionaries that implements the complete :py:class:`collections.Mapping`
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interface. It can be used as a drop-in replacement for dictionaries where immutability is desired.
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"""
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dict_cls = dict
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def __init__(self, *args, **kwargs):
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self._dict = self.dict_cls(*args, **kwargs)
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self._hash = None
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def __getitem__(self, key):
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return self._dict[key]
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def __contains__(self, key):
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return key in self._dict
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def copy(self, **add_or_replace):
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return self.__class__(self, **add_or_replace)
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def __iter__(self):
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return iter(self._dict)
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def __len__(self):
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return len(self._dict)
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def __repr__(self):
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return '<%s %r>' % (self.__class__.__name__, self._dict)
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def __hash__(self):
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if self._hash is None:
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h = 0
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for key, value in iteritems(self._dict):
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h ^= hash((key, value))
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self._hash = h
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return self._hash
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class FrozenOrderedDict(frozendict):
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"""
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A frozendict subclass that maintains key order
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"""
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dict_cls = OrderedDict
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if OrderedDict is NotImplemented:
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del FrozenOrderedDict
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