NAME

RDF::Prefixes - simple way to turn URIs into QNames

SYNOPSIS

my $context = RDF::Prefixes->new;
say $context->qname('http://purl.org/dc/terms/title');  # dc:title
say $context->qname('http://example.net/rdf/dc#title'); # dc2:title
say $context->turtle;  # @prefix dc: <http://purl.org/dc/terms/> .
                       # @prefix dc2: <http://example.net/rdf/dc#> .

DESCRIPTION

This module is not so much for managing namespaces/prefixes in code (see RDF::Trine::NamespaceMap for that), but as a helper for code that serialises data using namespaces.

It generates pretty prefixes, reducing "http://purl.org/dc/terms/" to "dc" rather than something too generic like like "ns01", and provides a context for keeping track of namespaces already used, so that when "http://purl.org/dc/elements/1.1/" is encountered, it won't stomp on the previous definition of "dc".

Constructor

new(\%suggestions, \%options)

Creates a new RDF prefix context.

Suggestions for prefix mappings may be given, but there's no guarantee that they'll be used.

The only option right now is 'syntax' that is used by the to_string method.

Both hashrefs are optional.

Methods

get_prefix($uri)

Gets the prefix associated with a URI. e.g. get_prefix('http://purl.org/dc/terms/') might return 'dc'.

get_qname($uri)

Gets a QName for a URI. e.g. get_qname('http://purl.org/dc/terms/title') might return 'dc:title'.

Some URIs cannot be converted to QNames. In these cases, undef is returned.

get_curie($uri)

As per get_qname, but allows for more relaxed return values, suitable for RDFa, Turtle or Notation 3, but not RDF/XML. Should never need to return undef.

preview_prefix($uri), preview_qname($uri), preview_curie($uri)

As per the "get" versions of these methods, but doesn't modify the context.

to_hashref

Returns a hashref of prefix mappings used so far. This is not especially necessary as the object may be treated as a hashref directly:

foreach my $prefix (keys %$context)
{
  printf("%s => %s\n", $prefix, $context->{$prefix});
}

TO_JSON

A synonym for to_hashref, provided for the benefit of the JSON package.

rdfa

Return the same data as to_hashref, but as a string suitable for placing in an RDFa 1.1 prefix attribute.

sparql

Return the same data as to_hashref, but as a string suitable for prefixing a SPARQL query.

turtle

Return the same data as to_hashref, but as a string suitable for prefixing a Turtle or Notation 3 file.

xmlns

Return the same data as to_hashref, but as a string of xmlns attributes, suitable for use with RDF/XML or RDFa.

to_string

Calls either rdfa, sparql, turtle (the default) or xmlns, based on the 'syntax' option passed to the constructor. This module overloads the stringification operator, so explicitly calling to_string is rarely necessary.

my $context  = RDF::Prefixes->new({}, {syntax=>'turtle'});
my $dc_title = 'http://purl.org/dc/terms/title';
print "# Prefixes\n" . $context;

Internationalisation

Strings passed to and from this module are expected to be utf8 character strings, not byte strings. This is not explicitly checked for, but will be checked in a future version, so be warned!

URIs containing non-Latin characters should "just work".

BUGS

Please report any bugs to http://rt.cpan.org/.

AUTHOR

Toby Inkster <tobyink@cpan.org>.

COPYRIGHT

Copyright 2010-2013 Toby Inkster

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

DISCLAIMER OF WARRANTIES

THIS PACKAGE IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.