NAME

       Attean::API::Model - RDF Model

VERSION

       This document describes Attean::API::Model version 0.019

DESCRIPTION

       The Attean::API::Model role defines a common API for all RDF models to conform to. It is
       provides a consistent interface for probing, counting, and retrieving Attean::API::Quads
       matching a pattern, as well as related functionality such as enumerating the graph names,
       and extracting structured data from the models' quads.

REQUIRED METHODS

       The following methods are required by the Attean::API::Model role:

       "get_quads( $subject, $predicate, $object, $graph )"
           Returns an Attean::API::Iterator for quads in the model that match the supplied
           $subject, $predicate, $object, and $graph.

           Any of these terms may be:

           * An Attean::API::Term object, in which case matching is equality-based

           * A Attean::API::Variable object or "undef", in which case that term will be
           considered as a wildcard for the purposes of matching

           * An ARRAY reference of Attean::API::Term objects, in which case the matching will be
           equality-based on the disjunction of the supplied terms

           The returned iterator conforms to both Attean::API::Iterator and
           Attean::API::QuadIterator.

       "count_quads( $subject, $predicate, $object, $graph )"
           Returns the number of quads in the model matching the supplied pattern (using the same
           matching semantics as "get_quads").

       "get_graphs"
           Returns an Attean::API::Iterator of distinct Attean::API::Term objects that are used
           in the graph position of quads in the model.

METHODS

       The Attean::API::Model role provides default implementations of the following methods:

       "get_bindings( $subject, $predicate, $object, $graph )"
           Returns an Attean::API::Iterator of Attean::API::Result objects corresponding to quads
           in the model matching the supplied pattern. For each Attean::API::Variable in the
           pattern list, a mapping will be present in the corresponding result object. For
           example, "$model->get_bindings( variable('s') )" will return an iterator of results
           containing just a mapping from 's' to subjects of all quads in the model.

       "get_list( $graph, $head )"
           Returns an Attean::API::Iterator of Attean::API::Term objects that are members of the
           rdf:List with the specified $head (and matching restricted to only the specified
           $graph).

       "get_sequence( $graph, $head )"
           Returns an Attean::API::Iterator of Attean::API::Term objects that are members of the
           rdf:Sequence with the specified $head (and matching restricted to only the specified
           $graph).

       "subjects( $predicate, $object, $graph )"
           Returns an Attean::API::Iterator of Attean::API::Term objects of all subjects of quads
           matching the supplied pattern (using the same matching semantics as "get_quads").

       "predicates( $subject, $object, $graph )"
           Returns an Attean::API::Iterator of Attean::API::Term objects of all predicates of
           quads matching the supplied pattern (using the same matching semantics as "get_quads"
           with an "undef" predicate).

       "objects( $subject, $predicate, $graph )"
           Returns an Attean::API::Iterator of Attean::API::Term objects of all objects of quads
           matching the supplied pattern (using the same matching semantics as "get_quads" with
           an "undef" object).

       "graphs( $subject, $predicate, $object )"
           Returns an Attean::API::Iterator of Attean::API::Term objects of all graphs of quads
           matching the supplied pattern (using the same matching semantics as "get_quads" with
           an "undef" graph).

       "graph_nodes( $graph )"
           Returns an Attean::API::Iterator of Attean::API::Term objects of unique subjects and
           objects present in the specified $graph.

BUGS

       Please report any bugs or feature requests to through the GitHub web interface at
       <https://github.com/kasei/attean/issues>.

SEE ALSO

AUTHOR

       Gregory Todd Williams  "<gwilliams@cpan.org>"

COPYRIGHT

       Copyright (c) 2014--2018 Gregory Todd Williams.  This program is free software; you can
       redistribute it and/or modify it under the same terms as Perl itself.