First express the valid syntax in BNF http://cui.unige.ch/db-research/Enseignement/analyseinfo/AboutBNF.html to avoid missing any rules.

Based on that write a parser which follows your rules. A parser loads actual syntax into a parse tree but in your example, a hash will suffice. This is just to start you off...

my $remains = $string;
my %parsed = ();
while ( $remains =~ /^\s*\<(.*)$/ ) { # for each tag...
    $remains = $1;
    #we expect an identifier
    ( $remains =~ /^\s*(\w+)(.*)$/ ) or die 'expected identifier';
    my $kwd = $1;
    $remains = $2;

    if ( $kwd eq 'vertical' ) {
        ( $remains =~ /^\s*(\w+)\s*\=\s*(\w+)(.*)$/ or die 'expected a
+ssignment';
        $parsed{ $kwd } and die 'duplicate definition';
        $parsed{ $kwd }{ $1 } = $2;
        $remains = $2;
        Exhausted( \$remains );
        next; # next tag
    }

    if ... # next tag processor goes here

}

[download]
You'll also need a simple routine Exhausted to make sure nothing is left inside a tag and something to deal with the closing of a named tag -- enough said?

-S

One world, one people

In reply to Re: some more Regex help reqd by anonymized user 468275
in thread some more Regex help reqd by Ananda

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.