=for advent_year 2009

=for advent_day 06

=for advent_title Santy Claus, why? Why are you taking our Perl module? WHY?

=for advent_author Bill 'N1VUX' Ricker

The F<xml_grep> utility and A<http://xmltwig.com/xmltwig/twig_stable.html#XML_Twig_101|XML-Twig 101> are good intros to the M<XML::Twig> suite, but that does not make for a very  interesting Calendar entry.


As you may have noticed, this year's Advent Calendar layout does not obscure the picture with the calendar squares (window shutters), but also does not have a full 25 windows. Since we have missed some days the last few years, this should not be a problem, right? Well, the X-Y coords and dates are hard coded, so skipping a day requires some fussy work. This clearly calls for a Perl script to parse the HTML file and increment the Day of all unused entries (only), to be run when we take a skip day. In case the authors and editors are very naughty or lazy and skip more than 3 days -- and thus will be getting coal in their stocking -- the script can even remove the last box(es) to delete a day incrementing beyond 25th.
 
=begin pre

perl -i.bak mod6.pl index.html
mv index.html.bak index.before.html
diff -u index.before.html index.html | tee result-diff.txt
...
-&lt;br&gt;&lt;div class="q"&gt;&lt;a href="4/" style="left:425px; top:  5px"&gt;4&lt;/a&gt;&lt;/div&gt;
-&lt;br&gt;&lt;div class="q"&gt;&lt;a href="" style="left:545px; top:  5px"&gt;5&lt;/a&gt;&lt;/div&gt;
-&lt;br&gt;&lt;div class="q"&gt;&lt;a href="" style="left:665px; top:  5px"&gt;6&lt;/a&gt;&lt;/div&gt;
...
-&lt;br&gt;&lt;div class="C"&gt;&lt;a href="" style="left:  5px; top: 52px"&gt;22&lt;/a&gt;&lt;/div&gt;
...
+&lt;br /&gt;&lt;div class="q"&gt;&lt;a href="4/" style="left:425px; top:  5px"&gt;4&lt;/a&gt;&lt;/div&gt;
+&lt;br /&gt;&lt;div class="q"&gt;&lt;a href="" style="left:545px; top:  5px"&gt;6&lt;/a&gt;&lt;/div&gt;
+&lt;br /&gt;&lt;div class="q"&gt;&lt;a href="" style="left:665px; top:  5px"&gt;7&lt;/a&gt;&lt;/div&gt;
...
+&lt;br /&gt;&lt;div class="C"&gt;&lt;a href="" style="left:  5px; top: 52px"&gt;23&lt;/a&gt;&lt;/div&gt;


=end pre

The result is fairly subtle: The A<result-diff.txt|Diff> as above is somewhat opaque. if you viewed this by opening the A<../|calendar page> door -- I<if not, you miss half the traditional seasonal fun> -- you may have noticed B<5> missing; if not, you may need to compare closely to the previous A<../index.before.html|page state>, to see that the boxes from C<5..22> were incremented. 

(Yes Virginia, there will be a Christmas door for the 25th.)

Since it's acting as XML, Twig does not normally respect original whitespace but the C<keep_spaces => 1> option assists us here.

XML-Twig is allergic to some HTML that is NOT well-formed XML, so until we upgrade to XHTML, the script needs to insert end-slash in to empty tags as needed and the HTML-only Entities.N<nest> 







=sourcedcode mod6.pl


=begin footnote nest

This does mean that F<< &lt;p&gt; >> tags need close tags F<< &lt;/p&gt; >>, and tags must be properly nested, B< not > straddled like F<< &lt;b&gt;&lt;i&gt; blah &lt;/b&gt;&lt;/i&gt; >>.

=end footnote