#! perl -slw
use strict;

my $polar	= 'DEHAW';		# Uniq E
my $charged	= 'DGYAH';		# Uniq Y
my $hydphb	= 'GAFIVL';		# Uniq FIVL

my $re_seq 		= qr[
  # Capture
  (   
      # start char                                         
	[$polar$charged]   

      # Must contain motif                      
	(?= .* H[$hydphb][$polar][$hydphb]W .* )

      # Mustn't contain more than 4 polar chars
	(?! (?: .* [$polar] ){5} )

      # 18-24 polar|hydphb chars
      # Excludes the start and end chars (Adjust if wrong!)
	[$polar$hydphb]{18,24}    
      
      # # end char        
	[$polar$charged]                         
  )
]x;

while( <DATA> ) {
	chomp;
	print "\nTesting '$_'";
	s[\s+#.*$][];
	print "matched: '$1'" while m[$re_seq]g;
}


__DATA__
YVVVVVVVVVVHVEVWVVY 				# 1 too short
YVVVVVVVVVVHVEVWVVVY 				# min match
YVVVVVVVVVVHVEVWVVVVVVVVVY	 		# max match
YVVVVVVVVVVHVEVWVVVVVVVVVVY 			# 1 too long
YVVVVVVVVVVHVEVWVVVVVVVVEY 			# max polar
YVVVVVVVVVVHVEVWVVVVVVVEEY 			# too many polar
YVVVVVVVVVVHVYVWVVVY 				# missing motif