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54 lines
1.9 KiB
Python
54 lines
1.9 KiB
Python
'''
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Generate UUID encoded using a user specified alphabet.
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'''
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import string, math, uuid as _uuid
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def num_to_string(number, alphabet, alphabet_len, pad_to_length=None):
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ans = []
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number = max(0, number)
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while number:
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number, digit = divmod(number, alphabet_len)
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ans.append(alphabet[digit])
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if pad_to_length is not None and pad_to_length > len(ans):
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ans.append(alphabet[0] * (pad_to_length - len(ans)))
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return ''.join(ans)
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def string_to_num(string, alphabet_map, alphabet_len):
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ans = 0
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for char in reversed(string):
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ans = ans * alphabet_len + alphabet_map[char]
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return ans
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class ShortUUID(object):
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def __init__(self, alphabet=None):
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# We do not include zero and one in the default alphabet as they can be
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# confused with the letters O and I in some fonts. And removing them
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# does not change the uuid_pad_len.
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self.alphabet = tuple(sorted(str(alphabet or (string.digits + string.ascii_letters)[2:])))
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self.alphabet_len = len(self.alphabet)
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self.alphabet_map = {c:i for i, c in enumerate(self.alphabet)}
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self.uuid_pad_len = int(math.ceil(math.log(1 << 128, self.alphabet_len)))
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def uuid4(self, pad_to_length=None):
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if pad_to_length is None:
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pad_to_length = self.uuid_pad_len
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return num_to_string(_uuid.uuid4().int, self.alphabet, self.alphabet_len, pad_to_length)
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def uuid5(self, namespace, name, pad_to_length=None):
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if pad_to_length is None:
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pad_to_length = self.uuid_pad_len
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return num_to_string(_uuid.uuid5(namespace, name).int, self.alphabet, self.alphabet_len, pad_to_length)
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def decode(self, encoded):
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return _uuid.UUID(int=string_to_num(encoded, self.alphabet_map, self.alphabet_len))
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_global_instance = ShortUUID()
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uuid4 = _global_instance.uuid4
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uuid5 = _global_instance.uuid5
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decode = _global_instance.decode
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