comparison cpack/p2r/lib/uripattern_constraint.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(uripattern, [
+		simplify/2
+   ,  pattern_uri/2
+	]).
+
+:- use_module(library(semweb/rdf_db), [ rdf_global_id/2 ]).
+
+:- multifile uripattern:def/2.
+
+%% uri_constraint(+P:uripattern,?X:uri) is nondet.
+%  Logical predicate implemented using delayed goals.
+pattern_uri(A,B) :- must_be(nonvar,A), resource(A,B).
+
+resource(P:A,PB) :- !, rdf_global_id(P:'',Q), plain(Q+A,PB).
+resource(A,B) :- plain(A,B).
+
+plain(\(M),B) :- def(M,A), (var(A) -> true; plain(A,B)).
+plain(A1/A2,B)  :- plain(A1+'/'+A2,B).
+plain(num(N),B) :- when((nonvar(N);nonvar(B)), atom_number1(B,N)).
+plain(enc(A),B) :- when((nonvar(A);nonvar(B)), www_form_encode1(A,B)).
+plain(atm(A),A).
+plain(A1+A2,B) :- 
+   freeze(A1,plain(A1,B1)),
+   freeze(A2,plain(A2,B2)),
+   when((ground(B1),ground(B2);ground(B)), atom_concat1(B1,B2,B)).
+plain(A,A)     :- atom(A).
+
+%% simplify(+P1:uri_pattern, -P2:uri_pattern) is nondet.
+%  Non-deterministic maximal reduction of URI pattern.
+simplify(E1,E3) :- 
+   reduce(E1,E2) *-> simplify(E2,E3); E1=E3.
+
+% simplify resource if possible, fails otherwise
+% The pattern must be nonvar.
+reduce(A,B) :- must_be(nonvar,A), reduce1(A,B).
+
+reduce1(num(N),A)     :- number(N), atom_number(A,N).
+reduce1(atm(A),A)     :- atomic(A).
+reduce1(\(A),B)       :- nonvar(A), def(A,B).
+reduce1(enc(A),B)     :- atomic(A), www_form_encode(A,B).
+reduce1(P:A,Q+A)      :- rdf_global_id(P:'',Q).
+reduce1(A/B,A+'/'+B).
+reduce1(A+B,A1+B)     :- reduce(A,A1).
+reduce1(A+B,A+B1)     :- reduce(B,B1). % nb to get past these, A and B must be nonvar
+reduce1(A+B,AB)       :- atom(A), atom(B), atom_concat(A,B,AB).
+reduce1((A+B)+C,A+BC) :- reduce1(B+C,BC). 
+reduce1(A+(B+C),AB+C) :- reduce1(A+B,AB).
+
+% ---------- support predicates ---------
+
+atom_number1(Atom,Number) :-
+   (nonvar(Number) -> number(Number); true),
+   atom_number(Atom,Number).
+
+www_form_encode1(Atom,Encoded) :-
+   (nonvar(Encoded) -> atomic(Encoded); true),
+   www_form_encode(Atom,Encoded).
+
+atom_concat1(A,B,AB) :-
+   (nonvar(AB) -> atomic(AB); true),
+   atom_concat(A,B,AB).
+