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(rdfql_runtime, 37 [ rdfql_carthesian/1, % +Bags 38 39 rdfql_bind_null/1, % +List 40 rdfql_cond_bind_null/1, % +List 41 rdfql_triple_in/2, % -Triple, +Triples 42 43 % SeRQL support 44 serql_compare/3, % +Comparison, +Left, +Right 45 serql_eval/2, % +Term, -Evaluated 46 serql_member_statement/2, % -Triple, +List 47 48 % SPAQRL support 49 sparql_true/1, % +Term 50 sparql_eval/2, % +Expression, -Result 51 sparql_find/5, % ?From, ?To, ?F, ?T, :Q 52 sparql_minus/2, % :Q1, :Q2 53 sparql_group/1, % :Query 54 sparql_group/3, % :Query, +OuterVars, +InnerVars 55 sparql_subquery/3, % +Proj, +Query, +Solutions 56 sparql_service/5, % +Silent, +URL, +Prefixes, +Vars, +QText 57 sparql_update/1 % +Updates 58 ]). 59:- use_module(library(nb_set)). 60:- use_module(library(debug)). 61:- use_module(serql_runtime). 62:- use_module(sparql_runtime). 63 64:- meta_predicate 65 rdfql_carthesian(). 66 67/** <module> SPARQL/SeRQL runtime support predicates 68 69This module provides runtime support for running compiled queries. I.e. 70it defines special constructs that may be emitted by the compiler and 71optmizer that are common to all query languages. Language specific 72runtime support is in serql_runtime.pl and sparql_runtime.pl 73 74@see serql_runtime.pl for the implementation of the SeRQL routines. 75@see sparql_runtime.pl for the implementation of the SPARQL routines. 76*/ 77 78 /******************************* 79 * CARTHESIAN PRODUCT * 80 *******************************/ 81 82%! rdfql_carthesian(:Bags) is nondet. 83% 84% Bags is a list of independent goals. This predicate provides the 85% variable bindings for the carthesian product of all solutions of 86% each goal in Bags. For example: 87% 88% == 89% ?- rdfql_carthesian([ bag([X], between(1,2,X)), 90% bag([Y], between(1,2,Y))]). 91% X = 1, Y = 1 ; 92% X = 1, Y = 2 ; 93% X = 2, Y = 1 ; 94% X = 2, Y = 2 ; 95% false. 96% == 97 98rdfql_carthesian(M:Bags) :- 99 solve_bags(Bags, M, 1, Sets), 100 ( debugging(carthesian_size) 101 -> solution_set_size(Sets, Size), 102 debug(carthesian_size, 'Total size = ~D; NO select', [Size]) 103 ; true 104 ), 105 ( debugging(carthesian_no_select) 106 -> true 107 ; carthesian_select(Sets) 108 ). 109 110solve_bags([], _, _, []). 111solve_bags([bag(Templ, Goal, _Branch, _Cost)|T0], M, N, [set(Templ,Set,Size)|T]) :- 112 empty_nb_set(Set), 113 ( M:Goal, 114 add_nb_set(Templ, Set), 115 fail 116 ; true 117 ), 118 size_nb_set(Set, Size), 119 debug(carthesian_bags, 'Bag ~d: solution size = ~D', [N, Size]), 120 Size > 0, 121 N2 is N + 1, 122 solve_bags(T0, M, N2, T). 123 124 125carthesian_select([]). 126carthesian_select([call(Goal)|T]) :- 127 call(Goal), 128 carthesian_select(T). 129carthesian_select([set(Templ,Set,_)|T]) :- 130 gen_nb_set(Set, Templ), 131 carthesian_select(T). 132 133solution_set_size([], 0). 134solution_set_size([set(_,_,Len)|T], Size) :- 135 ( T == [] 136 -> Size = Len 137 ; solution_set_size(T, Size0), 138 Size is Len * Size0 139 ). 140 141 142 /******************************* 143 * NULL HANDLING * 144 *******************************/ 145 146%! rdfql_cond_bind_null(+List) is det. 147% 148% Bind variables in List to our NULL-representation, which is 149% =|$null$|=. 150 151rdfql_cond_bind_null([]). 152rdfql_cond_bind_null([H|T]) :- 153 ( var(H) 154 -> H = '$null$' 155 ; true 156 ), 157 rdfql_cond_bind_null(T). 158 159%! rdfql_bind_null(+List) is semidet. 160% 161% True if all elements in List unify with =|$null$|=. 162 163rdfql_bind_null([]). 164rdfql_bind_null(['$null$'|T]) :- 165 rdfql_bind_null(T). 166 167 168%! rdfql_triple_in(-Triple, +Triples) is nondet. 169% 170% True when Triple is an rdf(S,P,O) element in Triples that does 171% not contain NULL. Used for CONSTRUCT and DESCRIBE. 172 173rdfql_triple_in(Triple, Triples) :- 174 Triple = rdf(S,P,O), 175 member(Triple, Triples), 176 S \== '$null$', 177 P \== '$null$', 178 O \== '$null$'