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) 2013-2022, University of Amsterdam 7 VU University Amsterdam 8 SWI-Prolog Solutions b.v. 9 All rights reserved. 10 11 Redistribution and use in source and binary forms, with or without 12 modification, are permitted provided that the following conditions 13 are met: 14 15 1. Redistributions of source code must retain the above copyright 16 notice, this list of conditions and the following disclaimer. 17 18 2. Redistributions in binary form must reproduce the above copyright 19 notice, this list of conditions and the following disclaimer in 20 the documentation and/or other materials provided with the 21 distribution. 22 23 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 24 "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 25 LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 26 FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 27 COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 28 INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 29 BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 30 LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER 31 CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN 33 ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 34 POSSIBILITY OF SUCH DAMAGE. 35*/ 36 37:- module(turtle, 38 [ rdf_load_turtle/3, % +Input, -Triples, +Options 39 rdf_read_turtle/3, % +Input, -Triples, +Options 40 rdf_process_turtle/3, % +Input, :OnObject, +Options 41 % re-exports 42 rdf_save_turtle/2, % +File, +Options 43 rdf_save_canonical_turtle/2, % +File, +Options 44 rdf_save_trig/2, % +File, +Options 45 rdf_save_canonical_trig/2, % +File, +Options 46 rdf_save_ntriples/2 % +File, +Options 47 ]). 48:- use_module(library(semweb/rdf_turtle_write)). % re-exports 49:- if(exists_source(library(semweb/rdf_db))). 50:- use_module(library(semweb/rdf_db), 51 [rdf_transaction/2,rdf_set_graph/2,rdf_assert/4]). 52:- endif. 53 54:- autoload(library(memfile), 55 [atom_to_memory_file/2,open_memory_file/4]). 56:- autoload(library(option),[option/3,option/2]). 57:- autoload(library(uri), 58 [uri_file_name/2,uri_is_global/1,uri_normalized/2]). 59:- autoload(library(http/http_open),[http_open/3]). 60 61% re-exports 62:- meta_predicate 63 rdf_process_turtle(,,). 64 65:- predicate_options(rdf_load_turtle/3, 3, 66 [pass_to(rdf_read_turtle/3, 3)]). 67:- predicate_options(rdf_process_turtle/3, 3, 68 [ anon_prefix(atom), 69 base_uri(atom), 70 base_used(-atom), 71 db(atom), 72 error_count(-integer), 73 namespaces(-list), 74 on_error(oneof([warning,error])), 75 prefixes(-list), 76 resources(oneof([uri,iri])) 77 ]). 78:- predicate_options(rdf_read_turtle/3, 3, 79 [ anon_prefix(atom), 80 base_uri(atom), 81 base_used(-atom), 82 db(atom), 83 error_count(-integer), 84 namespaces(-list), 85 on_error(oneof([warning,error])), 86 prefixes(-list), 87 resources(oneof([uri,iri])) 88 ]). 89 90:- use_foreign_library(foreign(turtle)). 91:- public % used by the writer 92 turtle_pn_local/1, 93 turtle_write_quoted_string/2, 94 turtle_write_uri/2.
rdf(Subject, Predicate, Object [, Graph])
The representation is consistent with the SWI-Prolog RDF/XML and ntriples parsers. Provided options are:
node(1), node(2), ...auto (default), turtle or trig. The
auto mode switches to TriG format of there is a
{ before the first triple. Finally, of the
format is explicitly stated as turtle and the
file appears to be a TriG file, a warning is printed
and the data is loaded while ignoring the graphs.iri.prefixes(Pairs). Compatibility to rdf_load/2.warning (default), print the error and continue
parsing the remainder of the file. If error, abort
with an exception on the first error encountered.on_error(warning) is active, this option cane be
used to retrieve the number of generated errors.
167rdf_read_turtle(In, Triples, Options) :-
168 base_uri(In, BaseURI, Options),
169 setup_call_cleanup(
170 ( open_input(In, Stream, Close),
171 create_turtle_parser(Parser, Stream,
172 [ base_uri(BaseURI)
173 | Options
174 ])
175 ),
176 ( turtle_parse(Parser, Triples,
177 [ parse(document)
178 | Options
179 ]),
180 post_options(Parser, Options)
181 ),
182 ( destroy_turtle_parser(Parser),
183 call(Close)
184 )).
190rdf_load_turtle(Input, Triples, Options) :-
191 rdf_read_turtle(Input, Triples, Options).rdf(S,P,O) terms for a normal Turtle file or rdf(S,P,O,G) terms
if the GRAPH keyword is used to associate a set of triples in
the document with a particular graph. The Graph argument
provides the default graph for storing the triples and Line is
the line number where the statement started.
call(OnObject, ListOfTriples, Graph:Line)
This predicate supports the same Options as rdf_load_turtle/3.
Errors encountered are sent to print_message/2, after which the parser tries to recover and parse the remainder of the data.
218rdf_process_turtle(In, OnObject, Options) :- 219 base_uri(In, BaseURI, Options), 220 option(graph(Graph), Options, BaseURI), 221 setup_call_cleanup( 222 ( open_input(In, Stream, Close), 223 create_turtle_parser(Parser, Stream, Options) 224 ), 225 ( process_turtle(Parser, Stream, OnObject, Graph, 226 [ parse(statement) 227 ]), 228 post_options(Parser, Options) 229 ), 230 ( destroy_turtle_parser(Parser), 231 call(Close) 232 )). 233 234post_options(Parser, Options) :- 235 prefix_option(Parser, Options), 236 namespace_option(Parser, Options), 237 base_option(Parser, Options), 238 error_option(Parser, Options). 239 240prefix_option(Parser, Options) :- 241 ( option(prefixes(Pairs), Options) 242 -> turtle_prefixes(Parser, Pairs) 243 ; true 244 ). 245namespace_option(Parser, Options) :- 246 ( option(namespaces(Pairs), Options) 247 -> turtle_prefixes(Parser, Pairs) 248 ; true 249 ). 250base_option(Parser, Options) :- 251 ( option(base_used(Base), Options) 252 -> turtle_base(Parser, Base) 253 ; true 254 ). 255error_option(Parser, Options) :- 256 ( option(error_count(Count), Options) 257 -> turtle_error_count(Parser, Count) 258 ; true 259 ). 260 261 262process_turtle(_Parser, Stream, _OnObject, _Graph, _Options) :- 263 at_end_of_stream(Stream), 264 !. 265process_turtle(Parser, Stream, OnObject, Graph, Options) :- 266 stream_pair(Stream, In, _), 267 line_count(In, LineNo), 268 turtle_parse(Parser, Triples, 269 [ parse(statement) 270 | Options 271 ]), 272 call(OnObject, Triples, Graph:LineNo), 273 process_turtle(Parser, Stream, OnObject, Graph, Options).
284open_input(stream(Stream), Stream, Close) :- 285 !, 286 stream_property(Stream, encoding(Old)), 287 ( ( unicode_encoding(Old) 288 ; stream_property(Stream, type(text)) 289 ) 290 -> Close = true 291 ; set_stream(Stream, encoding(utf8)), 292 Close = set_stream(Stream, encoding(Old)) 293 ). 294open_input(Stream, Stream, Close) :- 295 is_stream(Stream), 296 !, 297 open_input(stream(Stream), Stream, Close). 298open_input(atom(Atom), Stream, close(Stream)) :- 299 !, 300 atom_to_memory_file(Atom, MF), 301 open_memory_file(MF, read, Stream, [free_on_close(true)]). 302open_input(URL, Stream, close(Stream)) :- 303 ( sub_atom(URL, 0, _, _, 'http://') 304 ; sub_atom(URL, 0, _, _, 'https://') 305 ), 306 !, 307 http_open(URL, Stream, []), 308 set_stream(Stream, encoding(utf8)). 309open_input(URL, Stream, close(Stream)) :- 310 uri_file_name(URL, Path), 311 !, 312 open(Path, read, Stream, [encoding(utf8)]). 313open_input(File, Stream, close(Stream)) :- 314 absolute_file_name(File, Path, 315 [ access(read), 316 extensions([ttl, '']) 317 ]), 318 open(Path, read, Stream, [encoding(utf8)]). 319 320unicode_encoding(utf8). 321unicode_encoding(wchar_t). 322unicode_encoding(unicode_be). 323unicode_encoding(unicode_le).
329base_uri(_Input, BaseURI, Options) :- 330 option(base_uri(BaseURI), Options), 331 !. 332base_uri(_Input, BaseURI, Options) :- 333 option(graph(BaseURI), Options), 334 !. 335base_uri(stream(Input), BaseURI, _Options) :- 336 stream_property(Input, file_name(Name)), 337 !, 338 name_uri(Name, BaseURI). 339base_uri(Stream, BaseURI, Options) :- 340 is_stream(Stream), 341 !, 342 base_uri(stream(Stream), BaseURI, Options). 343base_uri(Name, BaseURI, _Options) :- 344 atom(Name), 345 !, 346 name_uri(Name, BaseURI). 347base_uri(_, 'http://www.example.com/', _). 348 349name_uri(Name, BaseURI) :- 350 uri_is_global(Name), 351 !, 352 uri_normalized(Name, BaseURI). 353name_uri(Name, BaseURI) :- 354 uri_file_name(BaseURI, Name). 355 356 357 /******************************* 358 * WRITE SUPPORT * 359 *******************************/
turtle_write_quoted_string(Out, Value, false), writing a
string with only a single ". Embedded newlines are escapes
as \n.
394turtle_write_quoted_string(Out, Text) :-
395 turtle_write_quoted_string(Out, Text, false).<...>402 /******************************* 403 * RDF-DB HOOK * 404 *******************************/ 405 406:- if(current_predicate(rdf_transaction/2)). 407:- multifile 408 rdf_db:rdf_load_stream/3, 409 rdf_db:rdf_file_type/2.
415rdf_dbrdf_load_stream(turtle, Stream, Options) :- 416 load_turtle_stream(Stream, Options). 417rdf_dbrdf_load_stream(trig, Stream, Options) :- 418 load_turtle_stream(Stream, Options). 419 420load_turtle_stream(Stream, _Module:Options) :- 421 rdf_db:graph(Options, Graph), 422 atom_concat('_:', Graph, BNodePrefix), 423 rdf_transaction(( rdf_process_turtle(Stream, assert_triples, 424 [ anon_prefix(BNodePrefix) 425 | Options 426 ]), 427 rdf_set_graph(Graph, modified(false)) 428 ), 429 parse(Graph)). 430 431assert_triples([], _). 432assert_triples([H|T], Location) :- 433 assert_triple(H, Location), 434 assert_triples(T, Location). 435 436assert_triple(rdf(S,P,O), Location) :- 437 rdf_assert(S,P,O,Location). 438assert_triple(rdf(S,P,O,G), _) :- 439 rdf_assert(S,P,O,G). 440 441 442rdf_dbrdf_file_type(ttl, turtle). 443rdf_dbrdf_file_type(n3, turtle). % not really, but good enough 444rdf_dbrdf_file_type(trig, trig). 445:- endif. 446 447 448 /******************************* 449 * MESSAGES * 450 *******************************/ 451 452:- multifile prolog:error_message//1. 453 454prologerror_message(existence_error(turtle_prefix, '')) --> 455 [ 'Turtle empty prefix (:) is not defined' ]
Turtle: Terse RDF Triple Language
This module implements the Turtle language for representing the RDF triple model as defined by Dave Beckett from the Institute for Learning and Research Technology University of Bristol and later standardized by the W3C RDF working group.
This module acts as a plugin to rdf_load/2, for processing files with one of the extensions
.ttlor.n3.