51 lines
1.6 KiB
Python
51 lines
1.6 KiB
Python
# vim: tabstop=4 shiftwidth=4 softtabstop=4
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#
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# Copyright 2012 Nebula, Inc.
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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import functools
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class memoized(object):
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'''Decorator. Caches a function's return value each time it is called.
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If called later with the same arguments, the cached value is returned
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(not reevaluated).
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'''
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def __init__(self, func):
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self.func = func
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self.cache = {}
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def __call__(self, *args):
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try:
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return self.cache[args]
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except KeyError:
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value = self.func(*args)
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self.cache[args] = value
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return value
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except TypeError:
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# uncachable -- for instance, passing a list as an argument.
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# Better to not cache than to blow up entirely.
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return self.func(*args)
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def __repr__(self):
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'''Return the function's docstring.'''
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return self.func.__doc__ or ''
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def __get__(self, obj, objtype):
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'''Support instance methods.'''
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return functools.partial(self.__call__, obj)
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def __str__(self):
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return str(self.func)
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