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.