(?-xism:(?-xism:(?:\<(?:(?>[^\<\>]+)|(??{$Regexp::Common::balanced [0]}))*\>)))

##</code><code>##

#!/usr/bin/perl --
use strict; use warnings; 
use Test::More qw' no_plan ';
use Regexp::Common qw/ balanced /;
use Data::Dump qw/ dd pp /;
sub TRACE; sub DEBUG;
*TRACE = *DEBUG = sub { print STDERR @_,"\n" };
#~ *TRACE = *DEBUG = sub {  };

use vars qw/ $re_balanced_angles /;
#~ our $re_balanced_angles = qr{(?^:(?^:(?:\<(?:(?>[^\<\>]+)|(??{ $re_balanced_angles }))*\>)))}; 
#~ our $re_balanced_angles = qr{(?:(?:(?:\<(?:(?>[^\<\>]+)|(??{ $re_balanced_angles }))*\>)))}; 
#~ our $re_balanced_angles = qr{
#~ (?:
#~     (?:
#~         (?:
#~             \<
#~             (?:
#~                 (?>
#~                     [^\<\>]+
#~                 )
#~                 |
#~                 (??{ $re_balanced_angles })
#~             )*
#~             \>
#~         )
#~     )
#~ )}x; 
## still works the same 
#~ our $re_balanced_angles = qr{
#~             \<
#~             (?:
#~                 (?>
#~                     [^\<\>]+
#~                 )
#~                 |
#~                 (??{ $re_balanced_angles })
#~             )*
#~             \>
#~ }x;
#~ our $re_balanced_angles = qr{
#~             \<
#~             (?:
#~                 (?>
#~                     [^\<\>]+
#~                 )
#~                 |
#~                 (??{ $re_balanced_angles })
#~             )*
#~             \>
#~ }x;
our $re_balanced_angles = qr{
    \<
    (?:
        (?>
            [^\<\>]+
        )
        |
        (??{ $re_balanced_angles })
    )*
    \>
}x;


our $allowed = join '|', qw[
ABBR ACRONYM B BIG
CITE CODE DFN EM I KBD SAMP SMALL
SPAN STRONG SUB SUP TT VAR
];

{
    my $in = 'SPAN<text I<italic text>|class="span_class"> some more text B<bold text>.';
    my $out = shabba($in);
    my $wanted = '<span class="span_class">text <i>italic text</i></span> some more text <b>bold text</b>.';

    is( $out, $wanted , 'shabba');
}

{
    my $in = 'SPAN<text I<italic B<and bold> text>|class="span_class"> some more text B<bold text>.';
    my $out = shabba($in);
    my $wanted = '<span class="span_class">text <i>italic <b>and bold</b> text</i></span> some more text <b>bold text</b>.';

    is( $out, $wanted , 'shabba');
}

exit( 0 );


sub shabba {
    local $_ = $_[0];
    my $dent = $_[1] || 0;
    pos = 0;
    my $ret = "";
SHABBALOOP:
    while( length > pos ){
        m{\G(\s+)}gcsx and do {
            $ret .= $1;
            next SHABBALOOP;
        };
        m{
#~ \G( $allowed )( $RE{balanced}{-parens=>'<>'} )
\G( $allowed )( $re_balanced_angles )
        }gcsx and do {
            TRACE "# $dent allowed<> { $1 ( $2 ) }";
            $ret .= shabba_allowed( "$1" , "$2" , $dent );
            next SHABBALOOP;
        };


#~ confusion :)
#~ \G(\w+\b)
#~ fail #~ \G([^<]+)(?!:$allowed)\b
#~ \w+\b #~ \G([^<]+?)(?!:$allowed\<)\b
#~ fail #~ \G([^<]+?)(?!:$allowed\<)
#~ fail #~ \G([^<]+)(?!:$allowed\<)
#~ fail \G([^<]+)(?!:\<)
#~ inch #~ \G([^<]+?)(?!:\<)
#~ \G([^<]+?\b[^<])
#~ \G([^<]+?[^<])
#~ FAIL #~ \G([^<]+[^<])
#~ \G([^<]+[^<]\b)
#~ 2same#~ \G( (?!:$allowed\<) .+ )
#~ 2same#~ \G( .+(?!:$allowed\<) )

        m{
\G([^<]+\s)
        }gcmx and do {
            TRACE "# $dent text { $1 }";
            $ret .= shabba_text( "$1" );
            next SHABBALOOP;
        };;;
        
        m{
\G([\<\>])
        }gcmx and do {
            TRACE "## $dent error-stray<> { $1 } at pos(@{[pos]})";
            last SHABBALOOP;
        };;;
        m{
\G(\S)
        }gcmx and do {
            TRACE "# $dent inch-forward { $1 }";
            $ret .= shabba_text( "$1" );
            next SHABBALOOP;
        };;;
    }
    $ret;
}


sub shabba_allowed {
    my( $tag , $stuff, $dent ) = @_;
    $stuff = $1 if $stuff =~ m{^<(.*)>$}gs;
    
    my $ret = "";
    $ret .= "<\L$tag\E" if $tag;
    
    $stuff =~ s{\|([^<>]+)$}{
$ret .= " $1"; ## shabba_allowed_atts($tag,$1);
"";
    }gsex if defined $stuff ;
    
    $ret .= ">" if $tag;
    
    if( defined $stuff and length $stuff and $stuff =~ m{[<>]}g ){
        $ret .= shabba( $stuff , $dent+1) ; ## recurse
    } else {
        $ret .= $stuff;
    }
    
    $ret .= "</\L$tag\E>" if $tag;
    $ret;
}
sub shabba_text { join'',@_ }
__END__