1/* Part of SWI-Prolog 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(sparql, 37 [ sparql_query/3, % +Query, -Result, +Options 38 sparql_compile/3, % +Query, -Compiled, +Options 39 sparql_run/2 % +Compiled, -Reply 40 ]). 41:- use_module(library(option)). 42:- use_module(library(assoc)). 43:- use_module(library(apply)). 44:- use_module(library(semweb/rdf_db), [rdf_is_bnode/1]). 45:- use_module(library(semweb/rdf_optimise)). 46:- use_module(library(settings)). 47:- use_module(sparql_grammar). 48:- use_module(sparql_runtime). 49:- use_module(rdfql_util). 50:- use_module(library(settings)). 51:- include(entailment(load)). 52 53:- multifile 54 function/2. % user-defined functions 55 56:- setting(entailment, atom, rdf, 57 'Default entailment used for SPARQL queries').
| SELECT | row(Col1, Col2, ....) |
| CONSTRUCT | rdf(S,P,O) |
| DESCRIBE | rdf(S,P,O) |
| ASK | Reply == true or failure of pred |
Options are:
sparql:entailment.select(-VarNames), construct, describe or
ask.
88sparql_query(Query, Reply, Options) :-
89 sparql_compile(Query, Compiled, Options),
90 sparql_run(Compiled, Reply).100sparql_compile(Query, sparql_query(Optimised, ReplyTemplate, Module), Options) :- 101 sparql_parse(Query, Parsed, Options), 102 optimise(Parsed, Optimised, Options), 103 ( option(entailment(Entailment), Options) 104 -> true 105 ; setting(entailment, Entailment) 106 ), 107 option(type(Type), Options, _), 108 option(ordered(Order), Options, _), 109 option(distinct(Distinct), Options, _), 110 entailment_module(Entailment, Module), 111 prepare(Parsed, Type, Order, Distinct, ReplyTemplate). 112 113prepare(select(Vars, _, _, S), select(Names), O, D, Reply) :- 114 !, 115 select_result(Vars, Reply, Names), 116 solutions(S, O, D). 117prepare(construct(_,_,_,S), construct, O, D, _) :- 118 !, 119 solutions(S, O, D). 120prepare(ask(_,_,S), ask, O, D, _) :- 121 !, 122 solutions(S, O, D). 123prepare(describe(_,_,_,S), describe, O, D, _) :- 124 !, 125 solutions(S, O, D). 126prepare(update(_), update, false, false, _) :- !. 127prepare(Query, Type, _, _, _) :- 128 nonvar(Type), 129 functor(Type, Expected, _), 130 functor(Query, Found, _), 131 throw(error(type_error(query_type(Expected), Found), _)). 132 133solutions(distinct(S), O, true) :- 134 !, 135 solutions(S, O). 136solutions(S, O, false) :- 137 solutions(S, O). 138 139solutions(solutions(_Group, _Having, _Aggregate, unsorted, _, _), O) :- 140 !, 141 O = false. 142solutions(_, true).
153optimise(update(Updates), update(Updates), _) :- !. 154optimise(Parsed, Optimised, Options) :- 155 ( option(optimise(Optimise), Options) 156 -> Optimise == true 157 ; setting(cliopatria:optimise_query, true) 158 ), 159 prolog_goal(Parsed, Goal0), 160 simplify_group(Goal0, Goal1), 161 optimise_eval(Goal1, Goal2), 162 rdf_optimise(Goal2, Goal3), 163 !, 164 bind_null(Goal3, Goal, Options), 165 set_prolog_goal(Parsed, Goal, Optimised). 166optimise(Parsed, Optimised, Options) :- 167 prolog_goal(Parsed, Goal0), 168 simplify_group(Goal0, Goal1), 169 bind_null(Goal1, Goal, Options), 170 set_prolog_goal(Parsed, Goal, Optimised). 171 172% remove the outer SPARQL group. It has no meaning and reduces 173% readability. 174 175simplify_group(sparql_group(G), G) :- !. 176simplify_group(sparql_group(G, VIn, VOut), G) :- 177 VIn = VOut, 178 !. 179simplify_group(Goal, Goal). 180 181bind_null(Goal0, Goal, Options) :- 182 option(bind_null(true), Options), 183 !, 184 serql_select_bind_null(Goal0, Goal). 185bind_null(Goal, Goal, _). 186 187 188prolog_goal(select(_Proj, _DataSets, Goal, _Solutions), Goal). 189prolog_goal(construct(_Templ, _DataSets, Goal, _Solutions), Goal). 190prolog_goal(ask(_DataSets, Goal, _Solutions), Goal). 191prolog_goal(describe(_Proj, _DataSets, Goal, _Solutions), Goal). 192prolog_goal(sparql_group(Goal), Goal). 193prolog_goal(sparql_group(Goal,_VA,_VZ), Goal). 194 195set_prolog_goal(select(Proj, DataSets, _Goal, Solutions), Goal, 196 select(Proj, DataSets, Goal, Solutions)). 197set_prolog_goal(construct(Templ, DataSets, _Goal, Solutions), Goal, 198 construct(Templ, DataSets, Goal, Solutions)). 199set_prolog_goal(ask(DataSets, _Goal, Solutions), Goal, 200 ask(DataSets, Goal, Solutions)). 201set_prolog_goal(describe(Proj, DataSets, _Goal, Solutions), Goal, 202 describe(Proj, DataSets, Goal, Solutions)). 203set_prolog_goal(sparql_group(_Goal), Goal, Goal). 204set_prolog_goal(sparql_group(_Goal,VA,VZ), Goal, (Goal,VA=VZ)).
212optimise_eval(GoalIn, GoalOut) :-
213 annotate_variables(GoalIn, Vars),
214 optimise_annotated(GoalIn, GoalOut),
215 unbind_variables(Vars).annotations and the value of this
attribute is a list of annotations.223annotate_variables(Goal, Vars) :- 224 empty_assoc(Vars0), 225 annotate_vars(Goal, Vars0, Vars). 226 227annotate_vars(Var, _, _) :- 228 var(Var), 229 !, 230 instantiation_error(Var). 231annotate_vars((A,B), Vars0, Vars) :- 232 !, 233 annotate_vars(A, Vars0, Vars1), 234 annotate_vars(B, Vars1, Vars). 235annotate_vars((A;B), Vars0, Vars) :- 236 !, 237 annotate_vars(A, Vars0, Vars1), 238 annotate_vars(B, Vars1, Vars). 239annotate_vars((A*->B), Vars0, Vars) :- 240 !, 241 annotate_vars(A, Vars0, Vars1), 242 annotate_vars(B, Vars1, Vars). 243annotate_vars(sparql_group(G), Vars0, Vars) :- 244 !, 245 annotate_vars(G, Vars0, Vars). 246annotate_vars(sparql_group(G, _, _), Vars0, Vars) :- 247 !, 248 annotate_vars(G, Vars0, Vars). 249annotate_vars(rdf(S,P,_), Vars0, Vars) :- 250 !, 251 annotate_var(S, resource, Vars0, Vars1), 252 annotate_var(P, resource, Vars1, Vars). 253annotate_vars(rdf(S,P,_,G), Vars0, Vars) :- 254 !, 255 annotate_var(S, resource, Vars0, Vars1), 256 annotate_var(P, resource, Vars1, Vars2), 257 annotate_var(G, resource, Vars2, Vars). 258annotate_vars(_, Vars, Vars). 259 260annotate_var(V, Type, Vars0, Vars) :- 261 var(V), 262 ( get_attr(V, annotations, A0) 263 -> \+ memberchk(Type, A0) 264 ; A0 = [] 265 ), 266 !, 267 put_attr(V, annotations, [Type|A0]), 268 put_assoc(V, Vars0, true, Vars). 269annotate_var(_, _, Vars, Vars). 270 271unbind_variables(VarAssoc) :- 272 assoc_to_keys(VarAssoc, VarList), 273 maplist(unbind_var, VarList). 274 275unbind_var(V) :- 276 del_attr(V, annotations).
280optimise_annotated((A0,B0), (A,B)) :- 281 !, 282 optimise_annotated(A0, A), 283 optimise_annotated(B0, B). 284optimise_annotated((A0;B0), (A;B)) :- 285 !, 286 optimise_annotated(A0, A), 287 optimise_annotated(B0, B). 288optimise_annotated((A0*->B0), (A*->B)) :- 289 !, 290 optimise_annotated(A0, A), 291 optimise_annotated(B0, B). 292optimise_annotated(sparql_group(G0), sparql_group(G)) :- 293 !, 294 optimise_annotated(G0, G). 295optimise_annotated(sparql_group(G0, OV, IV), sparql_group(G, OV, IV)) :- 296 !, 297 optimise_annotated(G0, G). 298optimise_annotated(sparql_true(E), G) :- 299 !, 300 sparql_simplify(sparql_true(E), G). 301optimise_annotated(sparql_eval(E,V), G) :- 302 !, 303 sparql_simplify(sparql_eval(E,V), G). 304optimise_annotated(G, G).
314sparql_run(sparql_query(Parsed, Reply, Module), Reply) :- 315 sparql_reset_bnodes, 316 sparql_run(Parsed, Reply, Module). 317 318sparql_run(select(_Vars, _DataSets, Query, Solutions), Reply, Module) :- 319 select_results(Solutions, Reply, Module:Query). 320sparql_run(construct(Triples, _DataSets, Query, Solutions), Reply, Module) :- 321 select_results(Solutions, Reply, 322 Module:( Query, 323 rdfql_triple_in(Reply, Triples) 324 )). 325sparql_run(ask(_DataSets, Query, _Solutions), Result, Module) :- 326 ( Module:Query 327 -> Result = true 328 ; Result = false 329 ). 330sparql_run(describe(IRIs, _DataSets, Query, Solutions), Reply, Module) :- 331 select_results(Solutions, Reply, 332 ( Module:Query, 333 member(IRI, IRIs) 334 )), 335 sparql_describe(IRI, Module, Reply). 336sparql_run(update(Updates), Result, Module) :- 337 ( Module:sparql_update(Updates) 338 -> Result = true 339 ; Result = false 340 ).
348:- meta_predicate select_results(,,). 349:- public select_results/3. % used on sparql_subquery/4 350 351select_results(distinct(solutions(Group, Having, Agg, Order, Limit, Offset)), 352 Reply, Goal) :- 353 !, 354 select_results(distinct, Group, Having, Agg, Offset, Limit, 355 Order, Reply, Goal). 356select_results(reduced(Solutions), 357 Reply, Goal) :- 358 !, 359 select_results(Solutions, Reply, Goal). 360select_results(solutions(Group, Having, Agg, Order, Limit, Offset), 361 Reply, Goal) :- 362 select_results(all, Group, Having, Agg, Offset, Limit, 363 Order, Reply, Goal).
row(Col1, Col2, ...) and a term names(Name1, ...).
For example:
?- select_result([x=1,y=2], Row, Names). Row = row(1,2), Names = names(x,y)
377select_result(Bindings, Row, Names) :- 378 vars_in_bindings(Bindings, Vars, VarNames), 379 Names =.. [names|VarNames], 380 Row =.. [row|Vars]. 381 382vars_in_bindings([], [], []). 383vars_in_bindings([Name=Var|T0], [Var|T], [Name|NT]) :- 384 vars_in_bindings(T0, T, NT).
393sparql_describe(_Var=IRI, Module, Triple) :- 394 !, 395 sparql_describe(IRI, Module, Triple). 396sparql_describe(IRI, Module, Triple) :- 397 empty_assoc(Seen), 398 sparql_describe(IRI, Module, Triple, Seen). 399 400sparql_describe(IRI, Module, Triple, Seen) :- 401 Module:rdf(IRI, P, O), 402 ( rdf_is_bnode(O), 403 \+ get_assoc(O, Seen, true) 404 -> ( Triple = rdf(IRI, P, O) 405 ; put_assoc(O, Seen, true, Seen2), 406 sparql_describe(O, Module, Triple, Seen2) 407 ) 408 ; Triple = rdf(IRI, P, O) 409 )