Is it possible to make conditional regex of following?

Hello I am wondering whether it is possible to do this type of regex:

I have cert开发者_JS百科ain characters representing okjects i.e. #,@,$ and operations that may be used on them like +,-,%..... every object has a different set of operations and I want my regex to find valid pairs.

So for examle I want pairs #+, #-, $+ to be matched, but yair $- not to be matched as it is invalid.

So is there any way to do this with regexes only, without doing some gymnastics inside language using regex engine?

every okject with it's own rules in []

/(#[+-]|\$[+]|@[+-])/

you need to properly escape special characters

Gymnastics is hard. Try something like /#\+|#-|\$\+/ or something like that.

Just remember, +, $, and ^ are reserved, so they'll need to be escaped.

Another approach, mix not allowed with raw combinations, but this might be slower.
/(?!\$-|\$\%)([\#\$\@][+\-\%])/, though not if there are many alternations of the first character.

my $str = '
  #+, #-, $+ to be matched,
  but yair $- not to be matched asit is invalid.
  $% $- #% $%
';


my $regex = 
 qr/
  (?!\$-|\$\%)          # Specific combinations not allowed
  (
    [\#\$\@][+\-\%]     # Raw combinations allowed
  )
 /x;

while ( $str =~ /$regex/g ) {
   print "found: '$1'\n";
}

__END__

Output:

found: '#+'
found: '#-'
found: '$+'
found: '#%'