Ruby: Weird if-expression

gistfile1.txt

load 'wix.rb'

# FizzBuzz
1.upto(20) do |n|
  Wix.if { n % 3 == 0 }.then {
    print "Fizz"
  }.if { n % 5 == 0 }.then {
    print "Buzz"
  }.else {
    print n
  }
  puts
end

# NabeAzz
1.upto(40) do |n|
  Wix.if { n % 3 == 0 }
   .thenorif { /3/ =~ n.to_s }
   .then { print "<aho>" }
   .anyway { print n }
   .then { print "</aho>" }
   .anyway { print " " }
end
puts

wix.rb

module Wix
  class State
    def initialize(accum, prev)
      @accum, @prev = accum, prev
    end
    def if
      next_state(yield)
    end
    def thenandif
      next_state(@prev && yield)
    end
    def thenorif
      next_state(@prev || yield)
    end
    def ifaboveandif
      next_state(@accum && yield)
    end
    def ifaboveorif
      next_state(@accum || yield)
    end
    def elseandif
      next_state(!@accum && yield)
    end
    alias_method :elsif, :elseandif
    def elseorif
      next_state(!@accum || yield)
    end
    def next_state(curr)
      State.new(@accum || curr, curr)
    end
    private :next_state
    def then(&blk)
      dispatch(@prev, &blk)
    end
    def ifabove(&blk)
      dispatch(@accum, &blk)
    end
    def else(&blk)
      dispatch(!@accum, &blk)
    end
    def anyway(&blk)
      dispatch(true, &blk)
    end
    def dispatch(curr, &blk)
      if curr then yield end
      self
    end
    private :dispatch
  end

  InitState = State.new(false, true)
  def self.if(&blk)
    InitState.if(&blk)
  end
  def self.anyway(&blk)
    InitState.anyway(&blk)
  end
end