# File lib/rmail/mailbox/mboxreader.rb, line 42
      def initialize(input, line_separator = $/)
        super(input)
        @end_of_message = false
        @chunk_minsize = 0
        @sep = line_separator
        @tail = nil

        # This regexp will match a From_ header, or some prefix.
        re_string = RMail::Parser::PushbackReader.
          maybe_contains_re("#{@sep}From ")
        @partial_from_re = Regexp.new(re_string)

        # This regexp will match an entire From_ header.
        @entire_from_re = /\A#{@sep}From .*?#{@sep}/
      end