Yes sorry.

I didn't want to over complicate the question, and just wrote .*? between the markup.

Actually I'm using now something like (\S.*?(?<=\S)) to enforce at least one non-whitespace between the markers.

The objective of the question was "How best to allow * / _ to be chained and or nested".

The recursive approach does it already pretty well.

And actually nesting these markups is of rather low priority in the to-do list

> Can you supply some test cases for variations, especially WRT intermixtures with standard HTML?

That's my project: Wikisyntax for the Monastery =)

JS-regex is mostly compatible to Perl4 regex.

these are some tests I use ATM

sub is_tf {
    my ($in,$out,$label) = @_;
  
    is( rec( $in ) => $out => "$label: \t'$in'\t->\t'$out'" );
}
sub no_tf {
    my ($in,$label) = @_;

    is_tf($in,$in,$label);
}

no_tf( '**'  => "no letter" );
is_tf( '*A*' => '<b>A</b>'  => "one letter");
is_tf( '*A B*' ,'<b>A B</b>'  , "multi word");

no_tf( '* A*'   , "before non-whitespace");
no_tf( '*A *'   , "after non-whitespace");
no_tf( "*A\nB*" , "line break");

is_tf( '*A *B*' ,'<b>A *B</b>'  , "after non-whitespace prolonged");
is_tf( '/**/'   ,'<i>**</i>'    , "nested no letter");
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