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) 2013-2015, 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(turtle, 37 [ rdf_load_turtle/3, % +Input, -Triples, +Options 38 rdf_read_turtle/3, % +Input, -Triples, +Options 39 rdf_process_turtle/3, % +Input, :OnObject, +Options 40 % re-exports 41 rdf_save_turtle/2, % +File, +Options 42 rdf_save_canonical_turtle/2, % +File, +Options 43 rdf_save_trig/2, % +File, +Options 44 rdf_save_canonical_trig/2, % +File, +Options 45 rdf_save_ntriples/2 % +File, +Options 46 ]). 47:- use_module(library(option)). 48:- use_module(library(semweb/rdf_db)). 49:- use_module(library(semweb/rdf_turtle_write)). % re-exports 50:- use_module(library(uri)). 51:- use_module(library(http/http_open)). 52 53:- meta_predicate 54 rdf_process_turtle(,,). 55 56:- predicate_options(rdf_load_turtle/3, 3, 57 [pass_to(rdf_read_turtle/3, 3)]). 58:- predicate_options(rdf_process_turtle/3, 3, 59 [ anon_prefix(atom), 60 base_uri(atom), 61 base_used(-atom), 62 db(atom), 63 error_count(-integer), 64 namespaces(-list), 65 on_error(oneof([warning,error])), 66 prefixes(-list), 67 resources(oneof([uri,iri])) 68 ]). 69:- predicate_options(rdf_read_turtle/3, 3, 70 [ anon_prefix(atom), 71 base_uri(atom), 72 base_used(-atom), 73 db(atom), 74 error_count(-integer), 75 namespaces(-list), 76 on_error(oneof([warning,error])), 77 prefixes(-list), 78 resources(oneof([uri,iri])) 79 ]). 80 81:- use_foreign_library(foreign(turtle)). 82:- public % used by the writer 83 turtle_pn_local/1, 84 turtle_write_quoted_string/2, 85 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.
158rdf_read_turtle(In, Triples, Options) :-
159 base_uri(In, BaseURI, Options),
160 setup_call_cleanup(
161 ( open_input(In, Stream, Close),
162 create_turtle_parser(Parser, Stream,
163 [ base_uri(BaseURI)
164 | Options
165 ])
166 ),
167 ( turtle_parse(Parser, Triples,
168 [ parse(document)
169 | Options
170 ]),
171 post_options(Parser, Options)
172 ),
173 ( destroy_turtle_parser(Parser),
174 call()
175 )).
181rdf_load_turtle(Input, Triples, Options) :-
182 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.
209rdf_process_turtle(In, OnObject, Options) :- 210 base_uri(In, BaseURI, Options), 211 option(graph(Graph), Options, BaseURI), 212 setup_call_cleanup( 213 ( open_input(In, Stream, Close), 214 create_turtle_parser(Parser, Stream, Options) 215 ), 216 ( process_turtle(Parser, Stream, OnObject, Graph, 217 [ parse(statement) 218 ]), 219 post_options(Parser, Options) 220 ), 221 ( destroy_turtle_parser(Parser), 222 call() 223 )). 224 225post_options(Parser, Options) :- 226 prefix_option(Parser, Options), 227 namespace_option(Parser, Options), 228 base_option(Parser, Options), 229 error_option(Parser, Options). 230 231prefix_option(Parser, Options) :- 232 ( option(prefixes(Pairs), Options) 233 -> turtle_prefixes(Parser, Pairs) 234 ; true 235 ). 236namespace_option(Parser, Options) :- 237 ( option(namespaces(Pairs), Options) 238 -> turtle_prefixes(Parser, Pairs) 239 ; true 240 ). 241base_option(Parser, Options) :- 242 ( option(base_used(Base), Options) 243 -> turtle_base(Parser, Base) 244 ; true 245 ). 246error_option(Parser, Options) :- 247 ( option(error_count(Count), Options) 248 -> turtle_error_count(Parser, Count) 249 ; true 250 ). 251 252 253process_turtle(_Parser, Stream, _OnObject, _Graph, _Options) :- 254 at_end_of_stream(Stream), 255 !. 256process_turtle(Parser, Stream, OnObject, Graph, Options) :- 257 stream_pair(Stream, In, _), 258 line_count(In, LineNo), 259 turtle_parse(Parser, Triples, 260 [ parse(statement) 261 | Options 262 ]), 263 call(OnObject, Triples, Graph:LineNo), 264 process_turtle(Parser, Stream, OnObject, Graph, Options).
275open_input(stream(Stream), Stream, Close) :- 276 !, 277 stream_property(Stream, encoding(Old)), 278 ( unicode_encoding(Old) 279 -> Close = true 280 ; set_stream(Stream, encoding(utf8)), 281 Close = set_stream(Stream, encoding(Old)) 282 ). 283open_input(Stream, Stream, Close) :- 284 is_stream(Stream), 285 !, 286 open_input(stream(Stream), Stream, Close). 287open_input(atom(Atom), Stream, close(Stream)) :- 288 !, 289 atom_to_memory_file(Atom, MF), 290 open_memory_file(MF, read, Stream, [free_on_close(true)]). 291open_input(URL, Stream, close(Stream)) :- 292 ( sub_atom(URL, 0, _, _, 'http://') 293 ; sub_atom(URL, 0, _, _, 'https://') 294 ), 295 !, 296 http_open(URL, Stream, []), 297 set_stream(Stream, encoding(utf8)). 298open_input(URL, Stream, close(Stream)) :- 299 uri_file_name(URL, Path), 300 !, 301 open(Path, read, Stream, [encoding(utf8)]). 302open_input(File, Stream, close(Stream)) :- 303 absolute_file_name(File, Path, 304 [ access(read), 305 extensions([ttl, '']) 306 ]), 307 open(Path, read, Stream, [encoding(utf8)]). 308 309unicode_encoding(utf8). 310unicode_encoding(wchar_t). 311unicode_encoding(unicode_be). 312unicode_encoding(unicode_le).
318base_uri(_Input, BaseURI, Options) :- 319 option(base_uri(BaseURI), Options), 320 !. 321base_uri(_Input, BaseURI, Options) :- 322 option(graph(BaseURI), Options), 323 !. 324base_uri(stream(Input), BaseURI, _Options) :- 325 stream_property(Input, file_name(Name)), 326 !, 327 name_uri(Name, BaseURI). 328base_uri(Stream, BaseURI, Options) :- 329 is_stream(Stream), 330 !, 331 base_uri(stream(Stream), BaseURI, Options). 332base_uri(Name, BaseURI, _Options) :- 333 atom(Name), 334 !, 335 name_uri(Name, BaseURI). 336base_uri(_, 'http://www.example.com/', _). 337 338name_uri(Name, BaseURI) :- 339 uri_is_global(Name), 340 !, 341 uri_normalized(Name, BaseURI). 342name_uri(Name, BaseURI) :- 343 uri_file_name(BaseURI, Name). 344 345 346 /******************************* 347 * WRITE SUPPORT * 348 *******************************/
turtle_write_quoted_string(Out, Value, false), writing a
string with only a single ". Embedded newlines are escapes
as \n.
383turtle_write_quoted_string(Out, Text) :-
384 turtle_write_quoted_string(Out, Text, false).<...>391 /******************************* 392 * RDF-DB HOOK * 393 *******************************/ 394 395:- multifile 396 rdf_db:rdf_load_stream/3, 397 rdf_db:rdf_file_type/2.
403rdf_dbrdf_load_stream(turtle, Stream, Options) :- 404 load_turtle_stream(Stream, Options). 405rdf_dbrdf_load_stream(trig, Stream, Options) :- 406 load_turtle_stream(Stream, Options). 407 408load_turtle_stream(Stream, _Module:Options) :- 409 rdf_db:graph(Options, Graph), 410 atom_concat('_:', Graph, BNodePrefix), 411 rdf_transaction(( rdf_process_turtle(Stream, assert_triples, 412 [ anon_prefix(BNodePrefix) 413 | Options 414 ]), 415 rdf_set_graph(Graph, modified(false)) 416 ), 417 parse(Graph)). 418 419assert_triples([], _). 420assert_triples([H|T], Location) :- 421 assert_triple(H, Location), 422 assert_triples(T, Location). 423 424assert_triple(rdf(S,P,O), Location) :- 425 rdf_assert(S,P,O,Location). 426assert_triple(rdf(S,P,O,G), _) :- 427 rdf_assert(S,P,O,G). 428 429 430rdf_dbrdf_file_type(ttl, turtle). 431rdf_dbrdf_file_type(n3, turtle). % not really, but good enough 432rdf_dbrdf_file_type(trig, trig). 433 434 435 /******************************* 436 * MESSAGES * 437 *******************************/ 438 439:- multifile prolog:error_message//1. 440 441prologerror_message(existence_error(turtle_prefix, '')) --> 442 [ '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.