54 lines
1.5 KiB
Python
54 lines
1.5 KiB
Python
# Copyright (c) 2016, Neil Booth
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#
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# All rights reserved.
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#
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# See the file "LICENCE" for information about the copyright
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# and warranty status of this software.
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"""An enum-like type with reverse lookup.
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Source: Python Cookbook, http://code.activestate.com/recipes/67107/
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"""
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class EnumError(Exception):
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pass
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class Enumeration:
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def __init__(self, name, enumList):
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self.__doc__ = name
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lookup = {}
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reverseLookup = {}
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i = 0
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uniqueNames = set()
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uniqueValues = set()
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for x in enumList:
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if isinstance(x, tuple):
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x, i = x
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if not isinstance(x, str):
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raise EnumError("enum name {} not a string".format(x))
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if not isinstance(i, int):
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raise EnumError("enum value {} not an integer".format(i))
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if x in uniqueNames:
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raise EnumError("enum name {} not unique".format(x))
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if i in uniqueValues:
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raise EnumError("enum value {} not unique".format(x))
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uniqueNames.add(x)
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uniqueValues.add(i)
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lookup[x] = i
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reverseLookup[i] = x
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i = i + 1
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self.lookup = lookup
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self.reverseLookup = reverseLookup
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def __getattr__(self, attr):
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result = self.lookup.get(attr)
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if result is None:
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raise AttributeError('enumeration has no member {}'.format(attr))
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return result
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def whatis(self, value):
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return self.reverseLookup[value]
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