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  • Committer: john.lenton at canonical
  • Date: 2011-09-06 16:14:52 UTC
  • Revision ID: john.lenton@canonical.com-20110906161452-pa3g10r7rvyvaawy
umm ... I did stuff. Yes, yes, I did.

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shorturl/cb62.py
 
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import string
 
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import random
 
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from zipfile import crc32
 
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DIGITS = string.digits + string.uppercase + string.lowercase
 
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N = len(DIGITS)
 
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def _get_digits(username):
 
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    random.seed(crc32('01dQs' + username))
 
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    d = bytearray(DIGITS)
 
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    random.shuffle(d)
 
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    return str(d)
 
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def encode(number, username):
 
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    user_digits = _get_digits(username)
 
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    encoded = bytearray()
 
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    q = number
 
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    while 1:
 
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        q, r = divmod(q, N)
 
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        encoded.append(user_digits[r])
 
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        if not q:
 
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            break
 
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    return str(encoded)
 
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def decode(encoded, username):
 
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    user_digits = _get_digits(username)
 
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    number = 0
 
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    for i, c in enumerate(encoded):
 
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        number += user_digits.index(c) * N ** i
 
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    return number
 
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