lib::HTML::LinkUserrContributed Perl Documlib::HTML::LinkExtor(3)NAMEHTML::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.
24/Aug/1997 perl 5.005, patch 03 1
lib::HTML::LinkUserrContributed Perl Documlib::HTML::LinkExtor(3)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
the HTML::Parser manpage
AUTHOR
Gisle Aas <aas@sn.no>
24/Aug/1997 perl 5.005, patch 03 2