How to format a value following a directive?

Hello, I would like to format the value following a following directive: I would like to keep(guard) my TITLE of my songs while adding at the very beginning of my titles(securities) the field ALBUMARTIST with a space and a hyphen(link) at the end more the original TITLE but than when the ALBUM is a COMPILATION. What would give with for ARTIST: SUDUAYA and for TITLE: Gathering under The Sun that is:
Front: Gathering under the sun
After formatting(layout) of the value that if the album is a compilation defined as 1 in Mp3Tag: SUDUAYA - Gathering under the sun

Action: Format value
Field: Title
Format string $if($neql(%compilation%,1),%title%,%albumartist% - $regexp(%title%,'^.? - (.)$',$1))This will join AlbumArtist - Title only if title contains NOT string ' - '. You can run the action as many time as you like. It won't add multiple times the albumartist at the beginning of title. Please note that this will join the albumartist into an empty title and it does update album artist when it changes.
E.g.

  1. before action.
    Albumartist: queen
    Title: Innuendo
  2. After action - one or many times
    Albumartist: queen
    Title: queen - Innuendo
  3. Album artist changes (fix word case)
    Albumartist: Queen
    Title: queen - Innuendo
  4. After action - one or many times
    Albumartist: Queen
    Title: Queen - Innuendo

Thank you for your answer, it is exactly that I to look. But for it is valid only if the title does not contain '-' I May if it is not too much to ask to have a line of code that could allow himself to him(it) with a title the expression of which contains '-' In you thank.

OK. You can use the below but you may execute it only once or album artisth would be added multiple times.
$if($neql(%compilation%,1),%title%,%albumartist% - %title%)Nevertheless the previous code does not add albumartist only title has (space)-(space), not only '-'.