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