NAME

HTML::LinkExtor - Extract links from an HTML document

SYNPOSIS

 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.

@links = $p->links

Return links found in the document as an array. Each array element contains an anonymous array with the follwing values:

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

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

EXAMPLE

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

HTML::Parser

AUTHOR

Gisle Aas <aas@sn.no>