Daniel@0: /* Part of DML (Digital Music Laboratory)
Daniel@0: 	Copyright 2014-2015 Samer Abdallah, University of London
Daniel@0: 	 
Daniel@0: 	This program is free software; you can redistribute it and/or
Daniel@0: 	modify it under the terms of the GNU General Public License
Daniel@0: 	as published by the Free Software Foundation; either version 2
Daniel@0: 	of the License, or (at your option) any later version.
Daniel@0: 
Daniel@0: 	This program is distributed in the hope that it will be useful,
Daniel@0: 	but WITHOUT ANY WARRANTY; without even the implied warranty of
Daniel@0: 	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
Daniel@0: 	GNU General Public License for more details.
Daniel@0: 
Daniel@0: 	You should have received a copy of the GNU General Public
Daniel@0: 	License along with this library; if not, write to the Free Software
Daniel@0: 	Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
Daniel@0: */
Daniel@0: 
Daniel@0: :- module(p2r_entailment,[ op(1200,xfx,<==), op(1200,xfx,==>), assert_all/1 ]).
Daniel@0: 
Daniel@0: /** <module> Prolog-to-RDF mapping entailment module
Daniel@0: 
Daniel@0:    This module provides a mechanism for exposing information in the Prolog
Daniel@0:    database as RDF triples. The basis of this is a syntax for multiheaded
Daniel@0:    Horn clauses with RDF triples in the head and Prolog goals in the body.
Daniel@0:    The rules can be written in either direction: as =|Heads <== Body|=
Daniel@0:    or =|Body ==> Heads|=, whichever is most convenient.
Daniel@0: 
Daniel@0:    There is also a grammar for writing  URI patterns. These are used to
Daniel@0:    to build URIs from Prolog values and to parse URIs to extract Prolog
Daniel@0:    values. The cost of this URI processing can be completely avoided by
Daniel@0:    writing only variables in the head rdf/3 terms.
Daniel@0: */
Daniel@0: 
Daniel@0: :- use_module(library(uripattern_detdcg)).
Daniel@0: :- use_module(library(semweb/rdf_db),[]).
Daniel@0: 
Daniel@0: :- rdf_meta rdf(r,r,o).
Daniel@0: :- rdf_meta rdf(r,r,o,-).
Daniel@0: 
Daniel@0: :- multifile cliopatria:entailment/2.
Daniel@0: :- multifile rdf/4.
Daniel@0: :- op(1200,xfx,<==).
Daniel@0: :- op(1200,xfx,==>).
Daniel@0: 
Daniel@0: 
Daniel@0: cliopatria:entailment(p2r, p2r_entailment).
Daniel@0: 
Daniel@0: rdf(S,P,O) :- rdf(S,P,O,_).
Daniel@0: 
Daniel@0: user:term_expansion( (Body ==> Heads), Clauses) :-
Daniel@0:    user:term_expansion( (Heads <== Body), Clauses).
Daniel@0: user:term_expansion( (Heads <== Body), Clauses) :-
Daniel@0:    debug(p2r,'Expanding: ~w',[Heads<==Body]),
Daniel@0: 	prolog_load_context(module,Mod),
Daniel@0:    expand_clauses(Heads,Mod:Body,Clauses,[]).
Daniel@0: 
Daniel@0: 
Daniel@0: expand_clauses((H1,H2),Body) --> !,
Daniel@0:    expand_clauses(H1,Body),
Daniel@0:    expand_clauses(H2,Body).
Daniel@0: 
Daniel@0: expand_clauses(rdf(SPat,PPat,OPat),Mod:Body) --> 
Daniel@0:    {  call_dcg( ( opt_match(resource,SPat,S),
Daniel@0:                   opt_match(resource,PPat,P),
Daniel@0:                   opt_match(object,OPat,O) ), Mod:Body, Body1),
Daniel@0:       Clause = (p2r_entailment:rdf(S,P,O,Mod) :- Body1), 
Daniel@0:       debug(p2r,'Asserting clause: ~w',[Clause])
Daniel@0:    },
Daniel@0:    [Clause].
Daniel@0: 
Daniel@0: % builds an optimised goal to do pattern matching
Daniel@0: opt_match(_,X,X) --> {var(X)}, !. 
Daniel@0: opt_match(object,X,Y) --> {X=literal(_)}, !, {rdf_global_object(X,Y)}. 
Daniel@0: opt_match(_,P1,URI) --> 
Daniel@0:    {debug(p2r,'Simplifying URI pattern: ~w',[P1])},
Daniel@0:    {simplify(P1,P2)}, opt_match(P2,URI).
Daniel@0: opt_match(X,X) --> {atomic(X)}, !.
Daniel@0: opt_match(P,U) --> by_inst(U,uripattern:pattern_uri(P,U)).
Daniel@0: 
Daniel@0: % this generates code to call G and G1 in an order determined
Daniel@0: % by the instantiation state of X at run time.
Daniel@0: by_inst(X,G1,G, (var(X) -> G, G1; G1, G)).
Daniel@0: 
Daniel@0: 
Daniel@0: %% assert_all(+Module) is det.
Daniel@0: %  This asserts all the RDF triples entailed by the p2r module Module.
Daniel@0: %  Informational messages are printed, including the time taken.
Daniel@0: assert_all(G) :-
Daniel@0:    forall(p2r_entailment:rdf(S,P,O,G), rdf_assert(S,P,O,G)).
Daniel@0: