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- # Copyright (c) 2010 Guilherme Gondim. All rights reserved.
- # Copyright (c) 2009 Simon Willison. All rights reserved.
- # Copyright (c) 2002 Drew Perttula. All rights reserved.
- #
- # License:
- # Python Software Foundation License version 2
- #
- # See the file "LICENSE" for terms & conditions for usage, and a DISCLAIMER OF
- # ALL WARRANTIES.
- #
- # This Baseconv distribution contains no GNU General Public Licensed (GPLed)
- # code so it may be used in proprietary projects just like prior ``baseconv``
- # distributions.
- #
- # All trademarks referenced herein are property of their respective holders.
- #
-
- """
- Convert numbers from base 10 integers to base X strings and back again.
-
- Sample usage::
-
- >>> base20 = BaseConverter('0123456789abcdefghij')
- >>> base20.encode(1234)
- '31e'
- >>> base20.decode('31e')
- 1234
- >>> base20.encode(-1234)
- '-31e'
- >>> base20.decode('-31e')
- -1234
- >>> base11 = BaseConverter('0123456789-', sign='$')
- >>> base11.encode('$1234')
- '$-22'
- >>> base11.decode('$-22')
- '$1234'
-
- """
-
- BASE2_ALPHABET = '01'
- BASE16_ALPHABET = '0123456789ABCDEF'
- BASE56_ALPHABET = '23456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnpqrstuvwxyz'
- BASE36_ALPHABET = '0123456789abcdefghijklmnopqrstuvwxyz'
- BASE62_ALPHABET = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz'
- BASE64_ALPHABET = BASE62_ALPHABET + '-_'
-
-
- class BaseConverter(object):
- decimal_digits = '0123456789'
-
- def __init__(self, digits, sign='-'):
- self.sign = sign
- self.digits = digits
- if sign in self.digits:
- raise ValueError('Sign character found in converter base digits.')
-
- def __repr__(self):
- return "<BaseConverter: base%s (%s)>" % (len(self.digits), self.digits)
-
- def encode(self, i):
- neg, value = self.convert(i, self.decimal_digits, self.digits, '-')
- if neg:
- return self.sign + value
- return value
-
- def decode(self, s):
- neg, value = self.convert(s, self.digits, self.decimal_digits, self.sign)
- if neg:
- value = '-' + value
- return int(value)
-
- def convert(self, number, from_digits, to_digits, sign):
- if str(number)[0] == sign:
- number = str(number)[1:]
- neg = 1
- else:
- neg = 0
-
- # make an integer out of the number
- x = 0
- for digit in str(number):
- x = x * len(from_digits) + from_digits.index(digit)
-
- # create the result in base 'len(to_digits)'
- if x == 0:
- res = to_digits[0]
- else:
- res = ''
- while x > 0:
- digit = x % len(to_digits)
- res = to_digits[digit] + res
- x = int(x // len(to_digits))
- return neg, res
-
- base2 = BaseConverter(BASE2_ALPHABET)
- base16 = BaseConverter(BASE16_ALPHABET)
- base36 = BaseConverter(BASE36_ALPHABET)
- base56 = BaseConverter(BASE56_ALPHABET)
- base62 = BaseConverter(BASE62_ALPHABET)
- base64 = BaseConverter(BASE64_ALPHABET, sign='$')
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