/
  ^
  [^.]+ \. \s      # Ignore the line numbers

  (.+?)            # Capture the file name

  (?:
    (\d) \s        # Capture the optional leading size digit
  ) ?

  (
    \d+ \. \d {2}  # Capture the rest of the size
  )

  \s MB .*
  $
/x