Class: Integer

Inherits:
Object
  • Object
show all
Defined in:
lib/ferret/number_tools.rb

Overview

Provides support for converting integers to Strings, and back again. The strings are structured so that lexicographic sorting order is preserved.

That is, if integer1 is less than integer2 for any two integers integer1 and integer2, then integer1.to_s_lex is lexicographically less than integer2.to_s_lex. (Similarly for “greater than” and “equals”.)

This class handles numbers between - 10 ** 10,000 and 10 ** 10,000 which should cover all practical numbers. If you need bigger numbers, increase Integer::LEN_STR_SIZE.

Constant Summary collapse

LEN_STR_SIZE =

LEN_SIZE of 4 should handle most numbers that can practically be held in memory.

4
NEG_LEN_MASK = 
10 ** LEN_STR_SIZE
LEN_STR_TEMPLATE = 
"%0#{LEN_STR_SIZE}d"

Instance Method Summary collapse

Instance Method Details

#to_s_lex ⇒ Object

Convert the number to a lexicographically sortable string. This string will use printable characters only but will not be human readable.



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# File 'lib/ferret/number_tools.rb', line 35

def to_s_lex
  if (self >= 0)
    num_str = self.to_s
    len_str = LEN_STR_TEMPLATE % num_str.size
    return len_str + num_str
  else
    num = self * -1
    num_str = num.to_s
    num_len = num_str.size
    len_str = LEN_STR_TEMPLATE % (NEG_LEN_MASK - num_len)
    num = (10 ** num_str.size) - num
    return "-#{len_str}%0#{num_len}d" % num
  end
end

#to_s_pad(width = 10) ⇒ Object

Convert the number to a lexicographically sortable string by padding with 0s. You should make sure that you set the width to a number large enough to accommodate all possible values. Also note that this method will not work with negative numbers. That is negative numbers will sort in the opposite direction as positive numbers. If you have very large numbers or a mix of positive and negative numbers you should use the Integer#to_s_lex method

width

number of characters in the string returned. Default is 10. So 123.to_s_pad(5) => 00123 and -123.to_s_pad(5) => -0123

return

padding string representation of the number.



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# File 'lib/ferret/number_tools.rb', line 60

def to_s_pad(width = 10)
  "%#{width}d" % self
end