1/* Part of ClioPatria SeRQL and SPARQL server 2 3 Author: Jan Wielemaker 4 E-mail: J.Wielemaker@vu.nl 5 WWW: http://www.swi-prolog.org 6 Copyright (c) 2010-2018, University of Amsterdam, 7 VU University Amsterdam 8 All rights reserved. 9 10 Redistribution and use in source and binary forms, with or without 11 modification, are permitted provided that the following conditions 12 are met: 13 14 1. Redistributions of source code must retain the above copyright 15 notice, this list of conditions and the following disclaimer. 16 17 2. Redistributions in binary form must reproduce the above copyright 18 notice, this list of conditions and the following disclaimer in 19 the documentation and/or other materials provided with the 20 distribution. 21 22 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 23 "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 24 LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 25 FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 26 COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 27 INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 28 BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 29 LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER 30 CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31 LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN 32 ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 33 POSSIBILITY OF SUCH DAMAGE. 34*/ 35 36:- module(rdf_describe, 37 [ rdf_bounded_description/4, % :Expand, +Type, +URI, -Graph 38 rdf_bounded_description/5, % :Expand, +Type, +Pattern, +URI, -Graph 39 resource_CBD/3, % :Expand, +URI, -Graph 40 graph_CBD/3, % :Expand, +Graph0, -Graph 41 rdf_include_reifications/3, % :Expand, +Graph0, -Graph 42 rdf_include_labels/3, % :Expand, +Graph0, -Graph 43 lcbd_label/3 % +Subject, -Pred, -Label 44 ]). 45:- use_module(library(semweb/rdf_db)). 46:- use_module(library(assoc)). 47:- use_module(library(lists)).
69:- meta_predicate 70 rdf_bounded_description(, , , ), 71 rdf_bounded_description(, , , , ), 72 rdf_include_labels(, , ), 73 resource_CBD(, , ), 74 graph_CBD(, , ), 75 rdf_include_reifications(, , ). 76 77 78 /******************************* 79 * RESOURCE OPERATIONS * 80 *******************************/
cbd, but includes triples with both URI as subject and
object.97rdf_bounded_description(Expand, Type, S, Graph) :- 98 rdf_bounded_description(Expand, Type, [], S, Graph). 99 100rdf_bounded_description(Expand, Type, Filter, S, Graph) :- 101 empty_assoc(Map0), 102 compile_pattern(Filter, Triple, Expand, Filter1), 103 expansion(Type, Expand, S, Triple, Filter1, Graph, BNG), 104 phrase(new_bnodes(Graph, Map0), BN), 105 phrase(r_bnodes(BN, Type, Expand, Map0, _Map), BNG). 106 107compile_pattern([], _, _, true). 108compile_pattern([rdf(S,P,O)], rdf(S,P,O), Expand, 109 call(Expand, S,P,O)) :- !. 110compile_pattern([rdf(S,P,O)|T], rdf(S,P,O), Expand, 111 ( call(Expand, S,P,O) ; More )) :- 112 compile_pattern(T, rdf(S,P,O), Expand, More). 113 114 115 116:- meta_predicate 117 expansion(, , , , , , ), 118 r_bnodes(, , , , , , ). 119 120expansion(cbd, Expand, S, rdf(S,P,O), Filter, RDF, Tail) :- 121 findall(rdf(S,P,O), (call(Expand, S,P,O),Filter), RDF, Tail). 122expansion(scbd, Expand, S, rdf(S,P,O), Filter, RDF, Tail) :- 123 findall(rdf(S,P,O), (call(Expand, S,P,O),Filter), RDF, T0), 124 findall(rdf(O,P,S), (call(Expand, O,P,S),Filter), T0, Tail). 125 126r_bnodes([], _, _, Map, Map) --> 127 []. 128r_bnodes([H|T], Type, Expand, Map0, Map, Graph, Tail) :- 129 rdf_is_bnode(H), 130 !, 131 put_assoc(H, Map0, true, Map1), 132 expansion(Type, Expand, H, _, true, Graph, Tail0), 133 phrase(new_bnodes(Graph, Map1), BN, T), 134 r_bnodes(BN, Type, Expand, Map1, Map, Tail0, Tail). 135r_bnodes([_|T], Type, Expand, Map0, Map) --> 136 r_bnodes(T, Type, Expand, Map0, Map). 137 138new_bnodes(Var, _) --> 139 { var(Var) }, 140 !. 141new_bnodes([rdf(S,_,O)|RDF], Map) --> 142 new_bnode(S, Map), 143 new_bnode(O, Map), 144 new_bnodes(RDF, Map). 145 146new_bnode(S, Map) --> { rdf_is_bnode(S), \+ get_assoc(S, Map, _) }, !, [S]. 147new_bnode(_, _) --> [].
162resource_CBD(Expand, S, Graph) :- 163 rdf_bounded_description(Expand, cbd, S, Graph). 164 165 166 /******************************* 167 * GRAPH OPERATIONS * 168 *******************************/
175graph_CBD(Expand, Graph0, Graph) :- 176 empty_assoc(Map0), 177 must_be(list, Graph0), 178 phrase(gr_cbd(Graph0, Expand, Map0, _Map), Graph). 179 180:- meta_predicate 181 gr_cbd(, , , , , ). 182 183gr_cbd([], _, Map, Map) --> 184 []. 185gr_cbd([rdf(S,P,O)|T], Expand, Map0, Map) --> 186 { rdf_is_bnode(S) 187 ; rdf_is_bnode(O) 188 }, 189 !, 190 [ rdf(S,P,O) ], 191 r_bnodes([S,O], cbd, Expand, Map0, Map1), 192 gr_cbd(T, Expand, Map1, Map). 193gr_cbd([Triple|T], Expand, Map0, Map) --> 194 [Triple], 195 gr_cbd(T, Expand, Map0, Map).
201rdf_include_reifications(Expand, Graph0, Graph) :- 202 phrase(reified_triples(Graph0, Expand), Statements), 203 ( Statements == [] 204 -> Graph = Graph0 205 ; graph_CBD(Expand, Statements, Statements1), 206 rdf_include_reifications(Expand, Statements1, Graph1), 207 append(Graph0, Graph1, Graph) 208 ). 209 210:- meta_predicate 211 reified_triples(, , , ), 212 reification(,,,,). 213 214reified_triples([], _) --> []. 215reified_triples([rdf(S,P,O)|T], Expand) --> 216 findall(T, reification(S,P,O,Expand,T)), 217 reified_triples(T, Expand). 218 219reification(S,P,O, Expand, Triple) :- 220 rdf_equal(SP, rdf:subject), 221 rdf_equal(PP, rdf:predicate), 222 rdf_equal(OP, rdf:object), 223 call(Expand, Stmt, SP, S), 224 call(Expand, Stmt, OP, O), 225 call(Expand, Stmt, PP, P), 226 ( Triple = rdf(Stmt, SP, S) 227 ; Triple = rdf(Stmt, PP, P) 228 ; Triple = rdf(Stmt, OP, O) 229 ).
call(Expand, S, P, O)
The predicate lcbd_label/3 does this for the standard definition, considering the properties rdfs:label, rdfs:comment and rdfs:seeAlso.
242rdf_include_labels(Expand, Graph0, Graph) :- 243 phrase(label_triples(Graph0, Expand), LabelRDF), 244 ( LabelRDF == [] 245 -> Graph = Graph0 246 ; append(Graph0, LabelRDF, Graph) 247 ). 248 249:- meta_predicate 250 label_triples(, , , ), 251 label_triple(, , ). 252 253label_triples([], _) --> []. 254label_triples([rdf(_,_,O)|T], Expand) --> 255 findall(T, label_triple(O,Expand,T)), 256 label_triples(T, Expand). 257 258label_triple(O, Expand, Triple) :- 259 call(Expand, O, LP, Label), 260 Triple = rdf(O, LP, Label). 261 262:- rdf_meta 263 lcbd_property(r).
269lcbd_label(S, P, Label) :- 270 lcbd_property(P), 271 rdf_has(S, P, Label). 272 273lcbd_property(rdfs:label). 274lcbd_property(rdfs:comment). 275lcbd_property(rdfs:seeAlso)
RDF Bounded descriptions
The predicates in this module deal with `RDF bounded descriptions'. A bounded description is a subgraph that describes a single resource (URI). Unfortunately, such an isolated description is not possible without the possibility of loosing semantics. We provide some meaningful approximations described in the literature.
Scanning the definitions given in the link below, we distinguish two ortogonal expansions: one expanding the graph and another adding either reifications or labels. Expansion is implemented by rdf_bounded_description/4, while the returned graph can be further expanded using rdf_include_reifications/3 and/or rdf_include_labels/3.