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/* 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(backend_rdf, 
      [  rdf//3 
      ,  in/5
      ]).

:- use_module(library(semweb/rdf_db)).
:- use_module(library(semweb/turtle)).
:- use_module(library(semweb/rdf_turtle_write)).
:- use_module(library(dcg_core)).

:- rdf_meta rdf(r,r,o,?,?).
rdf(S,P,O) --> [rdf(S,P,O)].

:- rdf_meta to_literal(+,o).
to_literal(integer(X), literal(type(xsd:integer,Y))) :- atom_number(Y,X).
to_literal(float(X),   literal(type(xsd:float,Y))) :- atom_number(Y,X).
to_literal(double(X),  literal(type(xsd:double,Y))) :- atom_number(Y,X).
to_literal(string(X),  literal(type(xsd:string,Y))) :- atom_string(Y,X).
to_literal(atom(X),literal(X)).

comp(Comp,Function,Input) -->
   {once(to_literal(Input,InputLit))},
   rdf(Comp,dmlcla:function,literal(Function)),
   rdf(Comp,dmlcla:input,InputLit).


inx(Triples,SS,PP,OO,_) :- 
   in(Triples,S,P,O,_),
   rdf_global_id(S,SS),
   rdf_global_id(P,PP),
   rdf_global_object(O,OO).

in(Triples,S,P,O,_) :- 
   number_vars_as_uris(Triples),
   member(rdf(S,P,O),Triples).

phrase_triple(Phrase,S,P,O,_) :-
   phrase(Phrase,Triples),
   number_vars_as_uris(Triples),
   member(rdf(S,P,O),Triples).


:- meta_predicate python_rdf(//,-).
python_rdf(Input,Output) :-
   phrase(Input,Triples),
   number_vars_as_uris(Triples),
   setup_call_cleanup(
      process_create( dml('python/rdf_wrapper.py'),[],
                      [ cwd(dml(python)), process(PID),
                        stdin(pipe(ToScript)), stdout(pipe(FromScript))]),
      (  call_cleanup(rdf_save_turtle(stream(ToScript),[expand(in(Triples)), silent(true)]), close(ToScript)),
         rdf_read_turtle(stream(FromScript),Output,[base_uri('_:tmp#')])
      ),
      (close(FromScript), process_wait(PID,Status))
   ),
   debug(backend,'Process exit status was: ~q',[Status]).

number_vars_as_uris(Term) :-
   term_variables(Term,Vars),
   seqmap(number_var_as_uri,Vars,1,_).
number_var_as_uri(Var,N,M) :-
   atom_number(NN,N),
   rdf_global_id(dmlcla:NN,Var),
   succ(N,M).