comparison cpack/p2r/entailment/p2r.pl @ 0:718306e29690 tip

commiting public release

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