1.rb

code = <<END
class Post
  class << self
  end
end
END

puts RubyVM::InstructionSequence.compile(code).disasm

###
sent-hil:ruby/ (trunk✗) $ ruby example.rb            [19:10:20]
== disasm: <RubyVM::InstructionSequence:<compiled>@<compiled>>==========
0000 trace            1                                               (   1)
0002 putspecialobject 3
0004 putnil           
0005 defineclass      :Post, <class:Post>, 3
0009 leave            
== disasm: <RubyVM::InstructionSequence:<class:Post>@<compiled>>========
0000 trace            2                                               (   1)
0002 trace            1                                               (   2)
0004 putself          
0005 putnil           
0006 defineclass      :singletonclass, singletonclass, 1
0010 trace            4                                               (   4)
0012 leave                                                            (   2)
== disasm: <RubyVM::InstructionSequence:singletonclass@<compiled>>======
0000 trace            2                                               (   2)
0002 putnil                                                           (   3)
0003 trace            4
0005 leave 

2.rb

require 'ripper'
require 'pp'
code = <<STR
class Post
  class << self
  end
end
STR
puts code
pp Ripper.lex(code)

sent-hil:ruby/ (trunk✗) $ ruby example.rb                                                                              [19:11:52]
class Post
  class << self
  end
end
[[[1, 0], :on_kw, "class"],
 [[1, 5], :on_sp, " "],
 [[1, 6], :on_const, "Post"],
 [[1, 10], :on_nl, "\n"],
 [[2, 0], :on_sp, "  "],
 [[2, 2], :on_kw, "class"],
 [[2, 7], :on_sp, " "],
 [[2, 8], :on_op, "<<"],
 [[2, 10], :on_sp, " "],
 [[2, 11], :on_kw, "self"],
 [[2, 15], :on_nl, "\n"],
 [[3, 0], :on_sp, "  "],
 [[3, 2], :on_kw, "end"],
 [[3, 5], :on_nl, "\n"],
 [[4, 0], :on_kw, "end"],
 [[4, 3], :on_nl, "\n"]]