You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: ruby-lex.rb
    path of file: ./repos/truffleruby/lib/mri/irb
    
    the code of the file until where you have to start completion: # frozen_string_literal: false
#
#   irb/ruby-lex.rb - ruby lexcal analyzer
#   	$Release Version: 0.9.6$
#   	$Revision$
#   	by Keiju ISHITSUKA(keiju@ruby-lang.org)
#
# --
#
#
#

require "ripper"
require "jruby" if RUBY_ENGINE == "jruby"

# :stopdoc:
class RubyLex

  class TerminateLineInput < StandardError
    def initialize
      super("Terminate Line Input")
    end
  end

  def initialize
    @exp
    
  def take_corresponding_syntax_to_kw_do(tokens, index)
    syntax_of_do = nil
    # Finding a syntax corresponding to "do".
    index.downto(0) do |i|
      tk = tokens[i]
      # In "continue", the token isn't the corresponding syntax to "do".
      non_sp_index = tokens[0..(i - 1)].rindex{ |t| t.event != :on_sp }
      first_in_fomula = false
      if non_sp_index.nil?
        first_in_fomula = true
      elsif [:on_ignored_nl, :on_nl, :on_comment].include?(tokens[non_sp_index].event)
        first_in_fomula = true
      end
      if is_method_calling?(tokens, i)
        syntax_of_do = :method_calling
        break if first_in_fomula
      elsif tk.event == :on_kw && %w{while until for}.include?(tk.tok)
        # A loop syntax in front of "do" found.
        #
        #   while cond do # also "until" or "for"
        #   end
        #
        # This "do" doesn't increment indent because the loop syntax already
        # incremented.
        syntax_of_do = :loop_syntax
        break if first_in_fomula
      end
    end
    syntax_of_do
  end