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"""Misc dict tools.""" |
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__all__ = ["hashdict"] |
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class hashdict(dict): |
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""" |
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hashable dict implementation, suitable for use as a key into |
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other dicts. |
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>>> h1 = hashdict({"apples": 1, "bananas":2}) |
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>>> h2 = hashdict({"bananas": 3, "mangoes": 5}) |
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>>> h1+h2 |
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hashdict(apples=1, bananas=3, mangoes=5) |
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>>> d1 = {} |
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>>> d1[h1] = "salad" |
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>>> d1[h1] |
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'salad' |
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>>> d1[h2] |
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Traceback (most recent call last): |
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... |
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KeyError: hashdict(bananas=3, mangoes=5) |
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based on answers from |
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http://stackoverflow.com/questions/1151658/python-hashable-dicts |
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""" |
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def __key(self): |
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return tuple(sorted(self.items())) |
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def __repr__(self): |
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return "{0}({1})".format( |
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self.__class__.__name__, |
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", ".join("{0}={1}".format(str(i[0]), repr(i[1])) for i in self.__key()), |
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) |
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def __hash__(self): |
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return hash(self.__key()) |
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def __setitem__(self, key, value): |
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raise TypeError( |
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"{0} does not support item assignment".format(self.__class__.__name__) |
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) |
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def __delitem__(self, key): |
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raise TypeError( |
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"{0} does not support item assignment".format(self.__class__.__name__) |
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) |
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def clear(self): |
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raise TypeError( |
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"{0} does not support item assignment".format(self.__class__.__name__) |
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) |
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def pop(self, *args, **kwargs): |
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raise TypeError( |
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"{0} does not support item assignment".format(self.__class__.__name__) |
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) |
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def popitem(self, *args, **kwargs): |
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raise TypeError( |
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"{0} does not support item assignment".format(self.__class__.__name__) |
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) |
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def setdefault(self, *args, **kwargs): |
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raise TypeError( |
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"{0} does not support item assignment".format(self.__class__.__name__) |
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) |
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def update(self, *args, **kwargs): |
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raise TypeError( |
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"{0} does not support item assignment".format(self.__class__.__name__) |
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) |
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def __add__(self, right): |
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result = hashdict(self) |
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dict.update(result, right) |
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return result |
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