From: Robert Klemme <shortcutter@...>
Date: 2010-04-04T19:20:05+09:00
Subject: Re: combined ranges...

On 04/03/2010 03:07 AM, Caleb Clausen wrote:
> On 4/2/10, Roger Pack <rogerpack2005@gmail.com> wrote:
>> Anybody know if there's an easy way to accomplish the equivalent of
>> this:
>>
>> [1..20, 30..46].each{|n|
>>  # n = 1,2,3,4,5..30, 31, 32
>> }
>>
>> ?
> 
> Oh, I wish for a real integer set class!

Well, there's Fixnum / Bignum:

irb(main):004:0> set = 0
=> 0
irb(main):005:0> set[1]
=> 0
irb(main):006:0> set |= (1 << 1)
=> 2
irb(main):007:0> set[1]
=> 1
irb(main):008:0> set |= (1 << 100)
=> 1267650600228229401496703205378
irb(main):009:0> set[1]
=> 1
irb(main):010:0> set[100]
=> 1

It's fairly easy to build something around that, e.g.

class IntSet
   include Enumerable

   def initialize
     @s = 0
   end

   def add? x
     @s[x] == 0 and @s |= (1 << x)
   end

   def add x
     add? x
     self
   end

   alias << add

   def delete? x
     @s[x] == 1 and @s ^= (1 << x)
   end

   def include? x
     @s[x] == 1
   end

   def each
     x  = 0
     it = 1 << x

     while it <= @s
       yield x if @s[x] == 1
       x += 1
       it <<= 1
     end

     self
   end
end

is = IntSet.new

is << 10 << 5 << 14

is.each {|x| p x}


Kind regards

	robert

-- 
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/