I'm looking for the way to limit line edit to accept only alphanumeric characters, dash and underscore (in whole line could be only one dash and one underscore), without spaces. I was looking at RegExp, but then I left this option, because I found some blog post which is explaining that RegExp is really slow. Now I don't know what is best way to limit line edit, so the output would be like I want.

What do you recommend me?