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 2010-2012 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.