given a (CrossRef) DOI, parse link header of HTTP request to get fulltext URLs

gistfile1.txt

sub extracter {

	# given a (CrossRef) DOI, parse link header of HTTP request to get fulltext URLs
	# see also: https://prospect.crossref.org/splash/

	# Eric Lease Morgan <emorgan@nd.edu>
	# February 12, 2014 - first cut
	
	# require
	use HTTP::Request;
	use LWP::UserAgent;

	# get input
	my $doi = shift;
	
	# initialize
	my %links   = ();
	my $pdf     = '';
	my $xml     = '';
	my $generic = '';
	
	# build an HTTP request and send it; redirection comes for free
	my $request    = HTTP::Request->new( GET => $doi );
	$request->header( Accept => "text/turtle" );
	my $user_agent = LWP::UserAgent->new;
	my $response   = $user_agent->request( $request );

	# process each link in the links header	
	foreach my $link ( split /, /, $response->header( 'link' ) ) { 

		# (re-)initialize
		my $pointer    = 0;
		my %attributes = ();
		
		# process each part of a link
		foreach my $part ( split /;/, $link ) {
	 
			# remove extra spaces
			$part =~ s/^ +//;
			$part =~ s/ +$//;
		
			# increment
			$pointer++;
		
			# skip the first part, the data URL
			next if ( $pointer == 1 );
				
			# process subsequent parts
			my ( $name, $value ) = split /=/, $part;
			$value =~ s/^\W+//;
			$value =~ s/\W+$//;
			$attributes{ $name } = $value;
					
		}
	
		# associate mime types with urls
		if    ( $attributes{ 'type' } eq 'application/pdf' ) { $pdf     = $attributes{ 'anchor' } }
		elsif ( $attributes{ 'type' } eq 'application/xml' ) { $xml     = $attributes{ 'anchor' } }
		elsif ( ! $attributes{ 'type' } )                    { $generic = $attributes{ 'anchor' } }

	}
	
	# stuff the result into a data structure
	$links{ $doi } = { 'pdf' => $pdf, 'xml' => $xml, 'generic' => $generic };
	
	# done
	return \%links;

}