identify_identifier

# File lib/irb/ruby-lex.rb, line 770
  def identify_identifier
    token = ""
    if peek(0) =~ /[$@]/
      token.concat(c = getc)
      if c == "@" and peek(0) == "@"
        token.concat getc
      end
    end

    while (ch = getc) =~ /\w|_/
      print ":", ch, ":" if RubyLex.debug?
      token.concat ch
    end
    ungetc
    
    if (ch == "!" || ch == "?") && token[0,1] =~ /\w/ && peek(0) != "="
      token.concat getc
    end

    # almost fix token

    case token
    when /^\$/
      return Token(TkGVAR, token)
    when /^\@\@/
      @lex_state = EXPR_END
      # p Token(TkCVAR, token)
      return Token(TkCVAR, token)
    when /^\@/
      @lex_state = EXPR_END
      return Token(TkIVAR, token)
    end
    
    if @lex_state != EXPR_DOT
      print token, "\n" if RubyLex.debug?

      token_c, *trans = TkReading2Token[token]
      if token_c
        # reserved word?

        if (@lex_state != EXPR_BEG &&
            @lex_state != EXPR_FNAME &&
            trans[1])
          # modifiers
          token_c = TkSymbol2Token[trans[1]]
          @lex_state = trans[0]
        else
          if @lex_state != EXPR_FNAME
            if ENINDENT_CLAUSE.include?(token)
              # check for ``class = val'' etc.
              valid = true
              case token
              when "class"
                valid = false unless peek_match?(/^\s*(<<|\w|::)/)
              when "def"
                valid = false if peek_match?(/^\s*(([+-\/*&\|^]|<<|>>|\|\||\&\&)=|\&\&|\|\|)/)
              when "do"
                valid = false if peek_match?(/^\s*([+-\/*]?=|\*|<|>|\&)/)
              when *ENINDENT_CLAUSE
                valid = false if peek_match?(/^\s*([+-\/*]?=|\*|<|>|\&|\|)/)
              else
                # no nothing
              end
              if valid
                if token == "do"
                  if ![TkFOR, TkWHILE, TkUNTIL].include?(@indent_stack.last)
                    @indent += 1
                    @indent_stack.push token_c
                  end
                else
                  @indent += 1
                  @indent_stack.push token_c
                end
#               p @indent_stack
              end

            elsif DEINDENT_CLAUSE.include?(token)
              @indent -= 1
              @indent_stack.pop
            end
            @lex_state = trans[0]
          else
            @lex_state = EXPR_END
          end
        end
        return Token(token_c, token)
      end
    end

    if @lex_state == EXPR_FNAME
      @lex_state = EXPR_END
      if peek(0) == '='
        token.concat getc
      end
    elsif @lex_state == EXPR_BEG || @lex_state == EXPR_DOT
      @lex_state = EXPR_ARG
    else
      @lex_state = EXPR_END
    end

    if token[0, 1] =~ /[A-Z]/
      return Token(TkCONSTANT, token)
    elsif token[token.size - 1, 1] =~ /[!?]/
      return Token(TkFID, token)
    else
      return Token(TkIDENTIFIER, token)
    end
  end