CSV::Parser#prepare_unquoted

# File tmp/rubies/ruby-3.3.0/lib/csv/parser.rb, line 663
def prepare_unquoted
  return if @quote_character.nil?

  no_unquoted_values = "\r\n".encode(@encoding)
  no_unquoted_values << @escaped_first_column_separator
  unless @liberal_parsing
    no_unquoted_values << @escaped_quote_character
  end
  @unquoted_value = Regexp.new("[^".encode(@encoding) +
                               no_unquoted_values +
                               "]+".encode(@encoding))
end