HTML::LinkExtor - Extract links from an HTML document
require HTML::LinkExtor;
$p = HTML::LinkExtor->new(\&cb, "http://www.perl.org/";);
sub cb {
my($tag, %links) = @_;
print "$tag @{[%links]}\n";
}
$p->parse_file("index.html");
HTML::LinkExtor is an HTML parser that extracts links from an
HTML document. 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
-
- $p = HTML::LinkExtor->new( $callback )$p = HTML::LinkExtor->new( $callback )
-
- $p = HTML::LinkExtor->new( $callback, $base )$p = HTML::LinkExtor->new( $callback, $base )
-
The constructor takes two optional arguments. 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 argument is an optional base URL used to absolutize all URLs found.
You need to have the URI module installed if you provide $base.
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.
- $p->links
-
Returns a list of all links found in the document. The returned
values will be anonymous arrays with the following elements:
[$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
between them 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 HTML::LinkExtor was created.
This is an example showing how you can extract links from a document
received using LWP:
use LWP::UserAgent;
use HTML::LinkExtor;
use URI::URL;
$url = "http://www.perl.org/";; # for instance
$ua = LWP::UserAgent->new;
# Set up a callback that collect image links
my @imgs = ();
sub callback {
my($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 different 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";
the HTML::Parser manpage, the HTML::Tagset manpage, LWP, the URI::URL manpage
Copyright 1996-2001 Gisle Aas.
This library is free software; you can redistribute it and/or
modify it under the same terms as Perl itself.
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