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): 2005-2012, University of Amsterdam 7 VU University Amsterdam 8 9 This program is free software; you can redistribute it and/or 10 modify it under the terms of the GNU General Public License 11 as published by the Free Software Foundation; either version 2 12 of the License, or (at your option) any later version. 13 14 This program is distributed in the hope that it will be useful, 15 but WITHOUT ANY WARRANTY; without even the implied warranty of 16 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 17 GNU General Public License for more details. 18 19 You should have received a copy of the GNU Lesser General Public 20 License along with this library; if not, write to the Free Software 21 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 22 23 As a special exception, if you link this library with other files, 24 compiled with a Free Software compiler, to produce an executable, this 25 library does not by itself cause the resulting executable to be covered 26 by the GNU General Public License. This exception does not however 27 invalidate any other reasons why the executable file might be covered by 28 the GNU General Public License. 29*/ 30 31 32:- module(sparql, 33 [ sparql_query/3, % +Query, -Result, +Options 34 sparql_compile/3, % +Query, -Compiled, +Options 35 sparql_run/2 % +Compiled, -Reply 36 ]). 37:- use_module(library(option)). 38:- use_module(library(assoc)). 39:- use_module(library(apply)). 40:- use_module(library(semweb/rdf_db), [rdf_is_bnode/1]). 41:- use_module(library(semweb/rdf_optimise)). 42:- use_module(library(settings)). 43:- use_module(sparql_grammar). 44:- use_module(sparql_runtime). 45:- use_module(rdfql_util). 46:- use_module(library(settings)). 47:- include(entailment(load)). 48 49:- multifile 50 function/2. % user-defined functions 51 52:- setting(entailment, atom, rdf, 53 '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.
84sparql_query(Query, Reply, Options) :-
85 sparql_compile(Query, Compiled, Options),
86 sparql_run(Compiled, Reply).96sparql_compile(Query, sparql_query(Optimised, ReplyTemplate, Module), Options) :- 97 sparql_parse(Query, Parsed, Options), 98 optimise(Parsed, Optimised, Options), 99 ( option(entailment(Entailment), Options) 100 -> true 101 ; setting(entailment, Entailment) 102 ), 103 option(type(Type), Options, _), 104 option(ordered(Order), Options, _), 105 option(distinct(Distinct), Options, _), 106 entailment_module(Entailment, Module), 107 prepare(Parsed, Type, Order, Distinct, ReplyTemplate). 108 109prepare(select(Vars, _, _, S), select(Names), O, D, Reply) :- !, 110 select_result(Vars, Reply, Names), 111 solutions(S, O, D). 112prepare(construct(_,_,_,S), construct, O, D, _) :- !, 113 solutions(S, O, D). 114prepare(ask(_,_,S), ask, O, D, _) :- !, 115 solutions(S, O, D). 116prepare(describe(_,_,_,S), describe, O, D, _) :- !, 117 solutions(S, O, D). 118prepare(update(_), update, false, false, _) :- !. 119prepare(Query, Type, _, _, _) :- 120 nonvar(Type), 121 functor(Type, Expected, _), 122 functor(Query, Found, _), 123 throw(error(type_error(query_type(Expected), Found), _)). 124 125solutions(distinct(S), O, true) :- !, 126 solutions(S, O). 127solutions(S, O, false) :- 128 solutions(S, O). 129 130solutions(solutions(_Group, _Having, _Aggregate, unsorted, _, _), O) :- !, 131 O = false. 132solutions(_, true).
143optimise(update(Updates), update(Updates), _) :- !. 144optimise(Parsed, Optimised, Options) :- 145 ( option(optimise(Optimise), Options) 146 -> Optimise == true 147 ; setting(cliopatria:optimise_query, true) 148 ), 149 prolog_goal(Parsed, Goal0), 150 simplify_group(Goal0, Goal1), 151 optimise_eval(Goal1, Goal2), 152 rdf_optimise(Goal2, Goal3), !, 153 bind_null(Goal3, Goal, Options), 154 set_prolog_goal(Parsed, Goal, Optimised). 155optimise(Parsed, Optimised, Options) :- 156 prolog_goal(Parsed, Goal0), 157 simplify_group(Goal0, Goal1), 158 bind_null(Goal1, Goal, Options), 159 set_prolog_goal(Parsed, Goal, Optimised). 160 161% remove the outer SPARQL group. It has no meaning and reduces 162% readability. 163 164simplify_group(sparql_group(G), G) :- !. 165simplify_group(sparql_group(G, VIn, VOut), G) :- 166 VIn = VOut, !. 167simplify_group(Goal, Goal). 168 169bind_null(Goal0, Goal, Options) :- 170 option(bind_null(true), Options), !, 171 serql_select_bind_null(Goal0, Goal). 172bind_null(Goal, Goal, _). 173 174 175prolog_goal(select(_Proj, _DataSets, Goal, _Solutions), Goal). 176prolog_goal(construct(_Templ, _DataSets, Goal, _Solutions), Goal). 177prolog_goal(ask(_DataSets, Goal, _Solutions), Goal). 178prolog_goal(describe(_Proj, _DataSets, Goal, _Solutions), Goal). 179prolog_goal(sparql_group(Goal), Goal). 180prolog_goal(sparql_group(Goal,_VA,_VZ), Goal). 181 182set_prolog_goal(select(Proj, DataSets, _Goal, Solutions), Goal, 183 select(Proj, DataSets, Goal, Solutions)). 184set_prolog_goal(construct(Templ, DataSets, _Goal, Solutions), Goal, 185 construct(Templ, DataSets, Goal, Solutions)). 186set_prolog_goal(ask(DataSets, _Goal, Solutions), Goal, 187 ask(DataSets, Goal, Solutions)). 188set_prolog_goal(describe(Proj, DataSets, _Goal, Solutions), Goal, 189 describe(Proj, DataSets, Goal, Solutions)). 190set_prolog_goal(sparql_group(_Goal), Goal, Goal). 191set_prolog_goal(sparql_group(_Goal,VA,VZ), Goal, (Goal,VA=VZ)).
199optimise_eval(GoalIn, GoalOut) :-
200 annotate_variables(GoalIn, Vars),
201 optimise_annotated(GoalIn, GoalOut),
202 unbind_variables(Vars).annotations and the value of this
attribute is a list of annotations.210annotate_variables(Goal, Vars) :- 211 empty_assoc(Vars0), 212 annotate_vars(Goal, Vars0, Vars). 213 214annotate_vars(Var, _, _) :- 215 var(Var), !, 216 instantiation_error(Var). 217annotate_vars((A,B), Vars0, Vars) :- !, 218 annotate_vars(A, Vars0, Vars1), 219 annotate_vars(B, Vars1, Vars). 220annotate_vars((A;B), Vars0, Vars) :- !, 221 annotate_vars(A, Vars0, Vars1), 222 annotate_vars(B, Vars1, Vars). 223annotate_vars((A*->B), Vars0, Vars) :- !, 224 annotate_vars(A, Vars0, Vars1), 225 annotate_vars(B, Vars1, Vars). 226annotate_vars(sparql_group(G), Vars0, Vars) :- !, 227 annotate_vars(G, Vars0, Vars). 228annotate_vars(sparql_group(G, _, _), Vars0, Vars) :- !, 229 annotate_vars(G, Vars0, Vars). 230annotate_vars(rdf(S,P,_), Vars0, Vars) :- !, 231 annotate_var(S, resource, Vars0, Vars1), 232 annotate_var(P, resource, Vars1, Vars). 233annotate_vars(rdf(S,P,_,G), Vars0, Vars) :- !, 234 annotate_var(S, resource, Vars0, Vars1), 235 annotate_var(P, resource, Vars1, Vars2), 236 annotate_var(G, resource, Vars2, Vars). 237annotate_vars(_, Vars, Vars). 238 239annotate_var(V, Type, Vars0, Vars) :- 240 var(V), 241 ( get_attr(V, annotations, A0) 242 -> \+ memberchk(Type, A0) 243 ; A0 = [] 244 ), !, 245 put_attr(V, annotations, [Type|A0]), 246 put_assoc(V, Vars0, true, Vars). 247annotate_var(_, _, Vars, Vars). 248 249unbind_variables(VarAssoc) :- 250 assoc_to_keys(VarAssoc, VarList), 251 maplist(unbind_var, VarList). 252 253unbind_var(V) :- 254 del_attr(V, annotations).
258optimise_annotated((A0,B0), (A,B)) :- !, 259 optimise_annotated(A0, A), 260 optimise_annotated(B0, B). 261optimise_annotated((A0;B0), (A;B)) :- !, 262 optimise_annotated(A0, A), 263 optimise_annotated(B0, B). 264optimise_annotated((A0*->B0), (A*->B)) :- !, 265 optimise_annotated(A0, A), 266 optimise_annotated(B0, B). 267optimise_annotated(sparql_group(G0), sparql_group(G)) :- !, 268 optimise_annotated(G0, G). 269optimise_annotated(sparql_group(G0, OV, IV), sparql_group(G, OV, IV)) :- !, 270 optimise_annotated(G0, G). 271optimise_annotated(sparql_true(E), G) :- !, 272 sparql_simplify(sparql_true(E), G). 273optimise_annotated(sparql_eval(E,V), G) :- !, 274 sparql_simplify(sparql_eval(E,V), G). 275optimise_annotated(G, G).
285sparql_run(sparql_query(Parsed, Reply, Module), Reply) :- 286 sparql_reset_bnodes, 287 sparql_run(Parsed, Reply, Module). 288 289sparql_run(select(_Vars, _DataSets, Query, Solutions), Reply, Module) :- 290 select_results(Solutions, Reply, Module:Query). 291sparql_run(construct(Triples, _DataSets, Query, Solutions), Reply, Module) :- 292 select_results(Solutions, Reply, 293 Module:( Query, 294 rdfql_triple_in(Reply, Triples) 295 )). 296sparql_run(ask(_DataSets, Query, _Solutions), Result, Module) :- 297 ( Module:Query 298 -> Result = true 299 ; Result = false 300 ). 301sparql_run(describe(IRIs, _DataSets, Query, Solutions), Reply, Module) :- 302 select_results(Solutions, Reply, 303 ( Module:Query, 304 member(IRI, IRIs) 305 )), 306 sparql_describe(IRI, Module, Reply). 307sparql_run(update(Updates), Result, Module) :- 308 ( Module:sparql_update(Updates) 309 -> Result = true 310 ; Result = false 311 ).
319:- meta_predicate select_results(,,). 320:- public select_results/3. % used on sparql_subquery/4 321 322select_results(distinct(solutions(Group, Having, Agg, Order, Limit, Offset)), 323 Reply, Goal) :- !, 324 select_results(distinct, Group, , Agg, Offset, Limit, 325 Order, Reply, ). 326select_results(reduced(Solutions), 327 Reply, Goal) :- !, 328 select_results(Solutions, Reply, ). 329select_results(solutions(Group, Having, Agg, Order, Limit, Offset), 330 Reply, Goal) :- 331 select_results(all, Group, , Agg, Offset, Limit, 332 Order, Reply, ).
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)
346select_result(Bindings, Row, Names) :- 347 vars_in_bindings(Bindings, Vars, VarNames), 348 Names =.. [names|VarNames], 349 Row =.. [row|Vars]. 350 351vars_in_bindings([], [], []). 352vars_in_bindings([Name=Var|T0], [Var|T], [Name|NT]) :- 353 vars_in_bindings(T0, T, NT).
362sparql_describe(_Var=IRI, Module, Triple) :- !, 363 sparql_describe(IRI, Module, Triple). 364sparql_describe(IRI, Module, Triple) :- 365 empty_assoc(Seen), 366 sparql_describe(IRI, Module, Triple, Seen). 367 368sparql_describe(IRI, Module, Triple, Seen) :- 369 Module:rdf(IRI, P, O), 370 ( rdf_is_bnode(O), 371 \+ get_assoc(O, Seen, true) 372 -> ( Triple = rdf(IRI, P, O) 373 ; put_assoc(O, Seen, true, Seen2), 374 sparql_describe(O, Module, Triple, Seen2) 375 ) 376 ; Triple = rdf(IRI, P, O) 377 )