class Base31Guid

This module is used to convert a base10 integer into an equivalent base31 guid string (and vice-versa). The base31 number is represented as a alpha-numeric characters (excluding the vowel charatcers A, E, I, O, U); this is done to avoid confusion between numbers and letters (eg. 1 and I, 0 and O) and also to avoid nasty words from being generated from their equivalent decimal values.

Constants

Dec_vals: base31/base10 equivalent string definitions

Public Class Methods

new(base_length=6) click to toggle source

# File lib/base31_guid.rb, line 21
def initialize(base_length=6)
  @base_length = base_length
end

Public Instance Methods

base31str_to_dec(str) click to toggle source

# File lib/base31_guid.rb, line 25
def base31str_to_dec(str)
  if not str.is_a?(String)
    raise StandardError, "Received value is not a valid string"
  end
  
  len = pos = str.length
  total = 0
  
  while pos > 0 do
    val = str[(len - pos), 1]
    intval = Dec_vals[val].to_i
    
    tmp = pos
    while (tmp - 1) > 0 do
      intval = intval * 31
      tmp -= 1
    end
    
    total += intval
    pos -= 1
  end
  
  return total
end

dec_to_base31(num) click to toggle source

# File lib/base31_guid.rb, line 50
def dec_to_base31(num)
  if not num.is_a?(Integer)
    raise StandardError, "Received value is not a valid integer"
  end
  
  base31 = ""
  
  while num > 0 do
    rem = num % 31
    num = num / 31
    val = Dec_vals[rem.to_s]
    
    base31 = val + base31
  end
  
  while base31.length < @base_length do
    base31 = "0" + base31
  end
  
  return base31
end