comparison cpack/p2r/lib/uripattern_dcg.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 ]).
+:- use_module(library(dcg/basics)).
+
+:- multifile uripattern:def/2.
+
+%% pattern_uri(+P:uripattern,-X:uri) is det.
+%% pattern_uri(-P:uripattern,+X:uri) is det.
+pattern_uri(P,URI) :-
+   (  var(URI) -> uri(P,Codes,[]), atom_codes(URI,Codes)
+   ;  atomic(URI) -> atom_codes(URI,Codes), uri(P,Codes,[])
+   ).
+
+uri(P:A) --> {rdf_global_id(P:'',Q)}, atom(Q), uri(A).
+uri(\(M)) --> {def(M,A)}, uri(A).
+uri(num(N)) --> number(N).
+uri(enc(A)) --> ( {var(A)} -> string(C), {atom_codes(B,C), www_form_encode(A,B)}
+                ; {www_form_encode(A,B)}, atom(B) ).
+uri(atm(A)) --> ( {var(A)} -> string(C), {atom_codes(A,C)}
+                ; atom(A) ).
+uri(A1/A2) --> uri(A1), "/", uri(A2).
+uri(A1+A2) --> uri(A1), uri(A2).
+uri(A)     --> {atomic(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).
+