Tooltron

# Copyright (c) 2010 Taurinus Collective. 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='$')