1/*  Part of ClioPatria SeRQL and SPARQL server
    2
    3    Author:        Jan Wielemaker
    4    E-mail:        J.Wielemaker@cs.vu.nl
    5    WWW:           http://www.swi-prolog.org
    6    Copyright (C): 2010, University of Amsterdam,
    7		   VU University Amsterdam
    8
    9    This program is free software; you can redistribute it and/or
   10    modify it under the terms of the GNU General Public License
   11    as published by the Free Software Foundation; either version 2
   12    of the License, or (at your option) any later version.
   13
   14    This program is distributed in the hope that it will be useful,
   15    but WITHOUT ANY WARRANTY; without even the implied warranty of
   16    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   17    GNU General Public License for more details.
   18
   19    You should have received a copy of the GNU General Public
   20    License along with this library; if not, write to the Free Software
   21    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
   22
   23    As a special exception, if you link this library with other files,
   24    compiled with a Free Software compiler, to produce an executable, this
   25    library does not by itself cause the resulting executable to be covered
   26    by the GNU General Public License. This exception does not however
   27    invalidate any other reasons why the executable file might be covered by
   28    the GNU General Public License.
   29*/
   30
   31:- module(rdf_description,
   32	  [ description_property/1,	% ?Property
   33	    rdf_description/2		% +Resource, ?Description
   34	  ]).   35:- use_module(library(semweb/rdf_db)).

   44:- rdf_meta
   45	description_property(r).   46:- multifile
   47	description_property/1,
   48	description_hook/2.

 description_property(?Property)

True when Property is used for descritive nodes on a resource. This predicate is multifile.

   55description_property(dc:description).
   56description_property(skos:scopeNote).
   57description_property(rdfs:comment).

 rdf_description(+R, -Description:literal) is nondet

Description is a description for R. This predicate first calls the hook description_hook/2. If this hook fails it produces all property-values for the properties defined by description_property/1 that have a literal value.

   67rdf_description(R, Description) :-
   68	(   description_hook(R, Description)
   69	*-> true
   70	;   description_property(P),
   71	    rdf_has(R, P, Description),
   72	    rdf_is_literal(Description)
   73	)