use strict;
use warnings;


undef $/;
$_ = <DATA>;                            # slurp




print "1: $1 - $2\n" while /<\s*(?!a\b|img\b)(\w+)\b(.*?)\s*>/g;

print "2: $1 - $2\n" while /<\s*(?!a|img)(\w+)(.*?)\s*>/g;

my %absent =
  (
   a=>1,
   img =>1
  );


while (/<\s*(\w+)(.*?)\s*>/g) {
   print "3: $1 - $2\n" unless $absent{$1};
}

while (/<\s*(\w+)\b(??{ $absent{$1} ? '^' : '' })(.*?)\s*>/g) {
   print "4: $1 - $2\n";
}




__DATA__
<a href='bla'>
<img href='bla'>
<table style="">
<anchor >
<tr width=100>

##</code><code>##

1: table -  style=""
1: anchor - 
1: tr -  width=100
2: table -  style=""
2: tr -  width=100
3: table -  style=""
3: anchor - 
3: tr -  width=100
4: table -  style=""
4: anchor - 
4: tr -  width=100