lib::HTML::LinkEUxsteorr(C3opnmt)ributed Perl Doculmiebn:t:aHtTiMoLn::LinkExtor(3pm)


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       HTML::LinkExtor - Extract links from an HTML document

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        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");


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       The _H_T_M_L_:_:_L_i_n_k_E_x_t_o_r (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 _H_T_M_L_:_:_L_i_n_k_E_x_t_o_r is a subclass of _H_T_M_L_:_:_P_a_r_s_e_r. This
       means that the document should be given to the parser by
       calling the $p->_p_a_r_s_e_(_) or $p->_p_a_r_s_e___f_i_l_e_(_) methods.

       $$$$pppp = HTML::LinkExtor->_n_e_w([$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->_l_i_n_k_s_(_) 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.

       $$$$pppp->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 _H_T_M_L_:_:_L_i_n_k_E_x_t_o_r
       manpage was created.





5/Apr/97               perl 5.004, patch 04                     1





lib::HTML::LinkEUxsteorr(C3opnmt)ributed Perl Doculmiebn:t:aHtTiMoLn::LinkExtor(3pm)


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       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";


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       the _H_T_M_L_:_:_P_a_r_s_e_r manpage

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       Gisle Aas <aas@sn.no>


















5/Apr/97               perl 5.004, patch 04                     2