(jeffa) Re: Why doens't non-greediness work?

I love questions like this! (in a sadistic sort of way!) They allow me to investigate more alternatives to using regexes to parse *ML ... like my new favorite XML::Twig. You really need to invest quite a bit of time into these kinds of solutions, but the time is well invested as it simply improves your overall programming skills. Here is my take on the problem:

use strict;
use warnings;
use XML::Twig;

my $twig = XML::Twig->new(
   twig_handlers => {
      'img[@alt="Smiley"]' => sub {
         XML::Twig::Elt->new('#PCDATA',':)')->replace($_)
      },
      'img[@alt="Wink"]' => sub {
         XML::Twig::Elt->new('#PCDATA',';)')->replace($_)
      },
   },
   pretty_print => 'indented',
);

$twig->parse(\*DATA);
$twig->flush;

__DATA__
<body>
<a href="wink.html">
   <img border="0" src="/images/wink.gif" alt="Wink"/>
</a>
<a href="smile.html">
   <img border="0" src="/images/smiley.gif" alt="Smiley"/>
</a>
</body>
[download]

It works, but i had to 'XML-ize' the image tags first. I wrapped the img tags inside a tags simply to show that other tags are outputted 'as-is'. Also, a big ++ to broquaint for helping get this right. I was trying to create a new XML::Twig::Elt object with 'CDATA' as the first arg. This created a <CDATA> tag pair - broquaint changed that to '#CDATA', which led me to the correct argument ... '#PCDATA'. Confusing? Start studying! ;)

jeffa

L-LL-L--L-LL-L--L-LL-L--
-R--R-RR-R--R-RR-R--R-RR
B--B--B--B--B--B--B--B--
H---H---H---H---H---H---
(the triplet paradiddle with high-hat)

Comment on (jeffa) Re: Why doens't non-greediness work? Download Code

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Re: (jeffa) Re: Why doens't non-greediness work? by Tomte (Priest) on May 10, 2003 at 20:49 UTC
++jeffa for that one, and not only for requiring correct xml-syntax ;-) , although IMNSHO every new bit of html put to the net should be xhtml 1.$0\|1$ regards, tomte Hlade's Law: If you have a difficult task, give it to a lazy person -- they will find an easier way to do it.	[reply]
Re: (jeffa) Re: Why doens't non-greediness work? by mirod (Canon) on May 11, 2003 at 05:51 UTC
And now of course I have to add my onw take to it! All you want to do is change some img tags, while leaving the rest of the file unchanged. This looks like a good opportunity to use `twig_roots`, which only builds the twig for the elements that have handlers, and the awfully named `twig_print_outside_roots`, that prints everything else in the document: #!/usr/bin/perl -w use strict; use warnings; use XML::Twig; my $twig = XML::Twig->new( twig_print_outside_roots => 1, twig_roots => { 'img[@alt="Smiley"]' => sub { print q{:)} }, 'img[@alt="Wink"]' => sub { print q{;)} }, }, ); $twig->parse(\*DATA); __DATA__ <body> <a href="wink.html"><img border="0" src="/images/wink.gif" alt="Wink"/ +></a> <a href="wink.html"><img border="0" src="/images/wink.gif" alt="NotWin +k"/></a> <a href="smile.html"><img border="0" src="/images/smiley.gif" alt="Smi +ley"/></a> </body> [download]	[reply] [d/l]
Re^2: Why doesn't non-greediness work? (HTML::TokeParser::Simple) by Aristotle (Chancellor) on May 11, 2003 at 11:54 UTC
For the parser types among us, there are likely more suitable options to be had though. `use strict; use warnings; use HTML::TokeParser::Simple; my %xlat = ( Smiley => ':)', Wink => ';)', ); my $p = HTML::TokeParser::Simple->new( \DATA ); while ( my $t = $p->get_token ) { if( $t->is_start_tag('img') and my $r = $xlat{$t->return_attr->{alt}} ) { print $r; } else { print $t->as_is; } } __END__ <body> <a href="wink.html"> <img border="0" src="/images/wink.gif" alt="Wink"> </a> <a href="smile.html"> <img border="0" src="/images/smiley.gif" alt="Smiley"> </a> </body>` [download] Note this doesn't require XHTML. Makeshifts last the longest.*	[reply] [d/l]