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1 /* Part of DML (Digital Music Laboratory)
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2 Copyright 2014-2015 Samer Abdallah, University of London
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3
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4 This program is free software; you can redistribute it and/or
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5 modify it under the terms of the GNU General Public License
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6 as published by the Free Software Foundation; either version 2
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7 of the License, or (at your option) any later version.
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8
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9 This program is distributed in the hope that it will be useful,
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10 but WITHOUT ANY WARRANTY; without even the implied warranty of
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11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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12 GNU General Public License for more details.
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13
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14 You should have received a copy of the GNU General Public
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15 License along with this library; if not, write to the Free Software
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16 Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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17 */
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18
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19 :- module(uripattern, [
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20 simplify/2
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21 , pattern_uri/2
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22 ]).
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23
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24 :- use_module(library(semweb/rdf_db), [ rdf_global_id/2 ]).
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25 :- use_module(library(dcg/basics)).
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26
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27 :- multifile uripattern:def/2.
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28
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29 %% pattern_uri(+P:uripattern,-X:uri) is det.
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30 %% pattern_uri(-P:uripattern,+X:uri) is det.
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31 pattern_uri(P,URI) :-
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32 ( var(URI) -> uri(P,Codes,[]), atom_codes(URI,Codes)
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33 ; atomic(URI) -> atom_codes(URI,Codes), uri(P,Codes,[])
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34 ).
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35
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36 uri(P:A) --> {rdf_global_id(P:'',Q)}, atom(Q), uri(A).
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37 uri(\(M)) --> {def(M,A)}, uri(A).
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38 uri(num(N)) --> number(N).
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39 uri(enc(A)) --> ( {var(A)} -> string(C), {atom_codes(B,C), www_form_encode(A,B)}
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40 ; {www_form_encode(A,B)}, atom(B) ).
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41 uri(atm(A)) --> ( {var(A)} -> string(C), {atom_codes(A,C)}
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42 ; atom(A) ).
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43 uri(A1/A2) --> uri(A1), "/", uri(A2).
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44 uri(A1+A2) --> uri(A1), uri(A2).
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45 uri(A) --> {atomic(A)}, atom(A).
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46
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47 %% simplify(+P1:uri_pattern, -P2:uri_pattern) is nondet.
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48 % Non-deterministic maximal reduction of URI pattern.
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49 simplify(E1,E3) :-
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50 reduce(E1,E2) *-> simplify(E2,E3); E1=E3.
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51
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52 % simplify resource if possible, fails otherwise
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53 % The pattern must be nonvar.
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54 reduce(A,B) :- must_be(nonvar,A), reduce1(A,B).
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55
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56 reduce1(num(N),A) :- number(N), atom_number(A,N).
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57 reduce1(atm(A),A) :- atomic(A).
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58 reduce1(\(A),B) :- nonvar(A), def(A,B).
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59 reduce1(enc(A),B) :- atomic(A), www_form_encode(A,B).
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60 reduce1(P:A,Q+A) :- rdf_global_id(P:'',Q).
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61 reduce1(A/B,A+'/'+B).
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62 reduce1(A+B,A1+B) :- reduce(A,A1).
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63 reduce1(A+B,A+B1) :- reduce(B,B1). % nb to get past these, A and B must be nonvar
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64 reduce1(A+B,AB) :- atom(A), atom(B), atom_concat(A,B,AB).
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65 reduce1((A+B)+C,A+BC) :- reduce1(B+C,BC).
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66 reduce1(A+(B+C),AB+C) :- reduce1(A+B,AB).
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67
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