HTML::LinkExtor - Extract links from an HTML document

SYNOPSIS

        require HTML::LinkExtor;
        $p = HTML::LinkExtor->new(\&cb, "http://www.sn.no/");
        sub cb {
            my($tag, %links) = @_;
            print "$tag @{[%links]}\n";
        }
        $p->parse_file("index.html");

DESCRIPTION

       The HTML::LinkExtor (link extractor) is an HTML parser
       that takes a callback routine as parameter.  This routine
       is then called as the various link attributes are
       recognized.

       The HTML::LinkExtor is a subclass of HTML::Parser. This
       means that the document should be given to the parser by
       calling the $p->parse() or $p->parse_file() methods.

       $p = HTML::LinkExtor->new([$callback[, $base]])
           The constructor takes two optional argument. The first
           is a reference to a callback routine. It will be
           called as links are found. If a callback is not
           provided, then links are just accumulated internally
           and can be retrieved by calling the $p->links()
           method. The $base is an optional base URL used to
           absolutize all URLs found.

           The callback is called with the lowercase tag name as
           first argument, and then all link attributes as
           separate key/value pairs.  All non-link attributes are
           removed.

       $p->links
           Returns a list of all links found in the document.
           The returned values will be anonymous arrays with the
           follwing elements:

             [$tag, $attr => $url1, $attr2 => $url2,...]

           The $p->links method will also truncate the internal
           link list.  This means that if the method is called
           twice without any parsing in between then the second
           call will return an empty list.

           Also note that $p->links will always be empty if a
           callback routine was provided when the the
           HTML::LinkExtor manpage was created.

       This is an example showing how you can extract links as a
       document is received using LWP:

         use LWP::UserAgent;
         use HTML::LinkExtor;
         use URI::URL;

         $url = "http://www.sn.no/";  # for instance
         $ua = new LWP::UserAgent;

         # Set up a callback that collect image links
         my @imgs = ();
         sub callback {
            my($tag, %attr) = @_;
            return if $tag ne 'img';  # we only look closer at <img ...>
            push(@imgs, values %attr);
         }

         # Make the parser.  Unfortunately, we don't know the base yet
         # (it might be diffent from $url)
         $p = HTML::LinkExtor->new(\&callback);

         # Request document and parse it as it arrives
         $res = $ua->request(HTTP::Request->new(GET => $url),
                             sub {$p->parse($_[0])});

         # Expand all image URLs to absolute ones
         my $base = $res->base;
         @imgs = map { $_ = url($_, $base)->abs; } @imgs;

         # Print them out
         print join("\n", @imgs), "\n";

SEE ALSO

       the HTML::Parser manpage

COPYRIGHT

       Copyright 1996-1997 Gisle Aas.

       This library is free software; you can redistribute it
       and/or modify it under the same terms as Perl itself.