Silly base 93 numbers

gistfile1.rb

module CompactUnsignedInt

  ASCII_RANGE = 33..126
  ASCII_LENGTH = ASCII_RANGE.last - ASCII_RANGE.first

  module InstanceMethods

    def to_compact_int
      base = to_i
      raise "Negative numbers will not convert" if base < 0
      base = base.abs
      result = []
      while base != 0
        div = base / ASCII_LENGTH
        rem = base % ASCII_LENGTH
        result << ((ASCII_RANGE.first + rem).chr)
        base = div
      end
      result.join
    end

  end

  module ClassMethods

    def from_compact_int(str)
      str = str.strip
      result = 0
      power = 0
      str.each_byte do |b|
        result += (b - ASCII_RANGE.first) * (ASCII_LENGTH ** power)
        power += 1
      end
      result
    end

  end

end
Integer.send(:include, CompactUnsignedInt::InstanceMethods)
Integer.send(:extend, CompactUnsignedInt::ClassMethods)

cnt = 1_000_000
sz = 0
0.upto(cnt).each do |i|
  compact = i.to_compact_int
  sz += compact.size
  raise "Error #{i}  : #{compact}" unless i == Integer.from_compact_int(compact)
end
puts "Average size is #{sz / cnt}"