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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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