I thought I had responded to this earlier. Actually, I did, but must have mistaken preview for submit (dammit).

BrowserUk stated my thoughts pretty well. As an aside, simply splitting the string and matching the tokens like so

    my @text = split /\s+/, $text;
    my @results;
    for (@text){
      push @results, $1 if m/\b($expr)\b/;
    }
[download]

is pretty slow in comparison to the solution I hit on.