1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342 1343 1344 1345 1346 1347 1348 1349 1350 1351 1352 1353 1354 1355 1356 1357 1358 1359 1360 1361 1362 1363 1364 1365 1366 1367 1368 1369 1370 1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 1411 1412 1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424 1425 1426 1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1448 1449 1450 1451 1452 1453 1454 1455 1456 1457 1458 1459 1460 1461 1462 1463 1464 1465 1466 1467 1468 1469 1470 1471 1472 1473 1474 1475 1476 1477 1478 1479 1480 1481 1482 1483 1484 1485 1486 1487 1488 1489 1490 1491 1492 1493 1494 1495 1496 1497 1498 1499 1500 1501 1502 1503 1504 1505 1506 1507 1508 1509 1510 1511 1512 1513 1514 1515 1516 1517 1518 1519 1520 1521 1522 1523 1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534 1535 1536 1537 1538 1539 1540 1541 1542 1543 1544 1545 1546 1547 1548 1549 1550 1551 1552 1553 1554 1555 1556 1557 1558 1559 1560 1561 1562 1563 1564 1565 1566 1567 1568 1569 1570 1571 1572 1573 1574 1575 1576 1577 1578 1579 1580 1581 1582 1583 1584 1585 1586 1587 1588 1589 1590 1591 1592 1593 1594 1595 1596 1597 1598 1599 1600 1601 1602 1603 1604 1605 1606 1607 1608 1609 1610 1611 1612 1613 1614 1615 1616 1617 1618 1619 1620 1621 1622 1623 1624 1625 1626 1627 1628 1629 1630 1631 1632 1633 1634 1635 1636 1637 1638 1639 1640 1641 1642 1643 1644 1645 1646 1647 1648 1649 1650 1651 1652 1653 1654 1655 1656 1657 1658 1659 1660 1661 1662 1663 1664 1665 1666 1667 1668 1669 1670 1671 1672 1673 1674 1675 1676 1677 1678 1679 1680 1681 1682 1683 1684 1685 1686 1687 1688 1689 1690 1691 1692 1693 1694 1695 1696 1697 1698 1699 1700 1701 1702 1703 1704 1705 1706 1707 1708 1709 1710 1711 1712 1713 1714 1715 1716 1717 1718 1719 1720 1721 1722 1723 1724 1725 1726 1727 1728 1729 1730 1731 1732 1733 1734 1735 1736 1737 1738 1739 1740 1741 1742 1743 1744 1745 1746 1747 1748 1749 1750 1751 1752 1753 1754 1755 1756 1757 1758 1759 1760 1761 1762 1763 1764 1765 1766 1767 1768 1769 1770 1771 1772 1773 1774 1775 1776 1777 1778 1779 1780 1781 1782 1783 1784 1785 1786 1787 1788 1789 1790 1791 1792 1793 1794 1795 1796 1797 1798 1799 1800 1801 1802 1803 1804 1805 1806 1807 1808 1809 1810 1811 1812 1813 1814 1815 1816 1817 1818 1819 1820 1821 1822 1823 1824 1825 1826 1827 1828 1829 1830 1831 1832 1833 1834 1835 1836 1837 1838 1839 1840 1841 1842 1843 1844 1845 1846 1847 1848 1849 1850 1851 1852 1853 1854 1855 1856 1857 1858 1859 1860 1861 1862 1863 1864 1865 1866 1867 1868 1869 1870 1871 1872 1873 1874 1875 1876 1877 1878 1879 1880 1881 1882 1883 1884 1885 1886 1887 1888 1889 1890 1891 1892 1893 1894 1895 1896 1897 1898 1899 1900 1901 1902 1903 1904 1905 1906 1907 1908 1909 1910 1911 1912 1913 1914 1915 1916 1917 1918 1919 1920 1921 1922 1923 1924 1925 1926 1927 1928 1929 1930 1931 1932 1933 1934 1935 1936 1937 1938 1939 1940 1941 1942 1943 1944 1945 1946 1947 1948 1949 1950 1951 1952 1953 1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030 2031 2032 2033 2034 2035 2036 2037 2038 2039 2040 2041 2042 2043 2044 2045 2046 2047 2048 2049 2050 2051 2052 2053 2054 2055 2056 2057 2058 2059
|
/* Part of SWI-Prolog
Author: Jan Wielemaker and Wouter Beek
E-mail: J.Wielemaker@vu.nl
WWW: http://www.swi-prolog.org
Copyright (c) 2015-2018, VU University Amsterdam
CWI, Amsterdam
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
1. Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in
the documentation and/or other materials provided with the
distribution.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
*/
:- module(rdf11,
[ rdf/3, % ?S, ?P, ?O
rdf/4, % ?S, ?P, ?O, ?G
rdf_has/3, % ?S, ?P, ?O
rdf_has/4, % ?S, ?P, ?O, -RealP
rdf_update/4, % +S, +P, +O, +Action
rdf_update/5, % +S, +P, +O, +G, +Action
rdf_reachable/3, % ?S, ?P, ?O
rdf_reachable/5, % ?S, ?P, ?O, +MaxD, -D
rdf_assert/3, % +S, +P, +O
rdf_assert/4, % +S, +P, +O, ?G
rdf_retractall/3, % ?S, ?P, ?O
rdf_retractall/4, % ?S, ?P, ?O, ?G
{}/1, % +Where
rdf_where/1, % +Where
rdf_compare/3, % -Diff, +Left, +Right
rdf_term/1, % ?Term
rdf_literal/1, % ?Term
rdf_bnode/1, % ?Term
rdf_iri/1, % ?Term
rdf_name/1, % ?Term
rdf_is_iri/1, % @Term
rdf_is_bnode/1, % @Term
rdf_is_literal/1, % @Term
rdf_is_name/1, % @Term
rdf_is_object/1, % @Term
rdf_is_predicate/1, % @Term
rdf_is_subject/1, % @Term
rdf_is_term/1, % @Term
rdf_subject/1, % ?Term
rdf_predicate/1, % ?Term
rdf_object/1, % ?Term
rdf_node/1, % ?Term
rdf_create_bnode/1, % ?Term
rdf_canonical_literal/2, % +In, -Canonical
rdf_lexical_form/2, % +Literal, -Lexical
rdf_default_graph/1, % -Graph
rdf_default_graph/2, % -Old, +New
rdf_estimate_complexity/4, % ?S, ?P, ?O, -Estimate
rdf_assert_list/2, % +PrologList, ?RDFList
rdf_assert_list/3, % +PrologList, ?RDFList, +G
rdf_last/2, % +RDFList, ?Last
rdf_list/1, % ?RDFList
rdf_list/2, % +RDFList, -PrologList
rdf_length/2, % ?RDFList, ?Length
rdf_member/2, % ?Member, +RDFList
rdf_nextto/2, % ?X, ?Y
rdf_nextto/3, % ?X, ?Y, ?RdfList
rdf_nth0/3, % ?Index, +RDFList, ?X
rdf_nth1/3, % ?Index, +RDFList, ?X
rdf_retract_list/1, % +RDFList
op(110, xfx, @), % must be above .
op(650, xfx, ^^), % must be above :
op(1150, fx, rdf_meta)
]).
:- use_module(library(c14n2)).
:- use_module(library(debug)).
:- use_module(library(error)).
:- use_module(library(lists)).
:- use_module(library(memfile)).
:- reexport(library(semweb/rdf_db),
except([ rdf/3,
rdf/4,
rdf_assert/3,
rdf_assert/4,
rdf_current_literal/1,
rdf_current_predicate/1,
rdf_has/3,
rdf_has/4,
rdf_update/4,
rdf_update/5,
rdf_reachable/3,
rdf_reachable/5,
rdf_retractall/3,
rdf_retractall/4,
rdf_node/1,
rdf_bnode/1,
rdf_is_literal/1,
rdf_is_resource/1,
rdf_literal_value/2,
rdf_compare/3,
rdf_estimate_complexity/4
])
).
:- use_module(library(sgml)).
:- use_module(library(solution_sequences)).
/** <module> RDF 1.1 API
This library provides a new API on top of library(semweb/rdf_db). The
new API follows the RDF 1.1 terminology and notation as much as
possible. It runs on top of the old API, which implies that applications
can use the new API in one file and the other in another one. Once the
new API is considered stable and robust the old API will be deprecated.
In a nutshell, the following issues are addressed:
- Literals are now represented by Value^^Type or Text@Lang. Plain
literals no longer exist. Value is a Prolog representation of
the value for known types. In particular:
- xsd:double, xsd:float and xsd:decimal are represented by a Prolog
float
- Integer types are represented by a Prolog integer
- The date/time types are presented by Prolog terms
- Literal matching and comparison operations are represented as
Prolog _constraints_. This replaces the literal(+Search,-Value)
construct used by library(semweb/rdf_db). For example, the following
query returns literals with prefix "ams", exploiting the RDF literal
index.
==
{ prefix(Name, "ams") },
rdf(S,P,Name).
==
- Graphs are always identified by the graph name only, i.e., the
notation Graph:Line is no longer supported. If a graph name is an IRI
then RDF prefix notation can now be used.
- The enumeration and type-testing predicates are now more closely based
on the RDF 1.1 specification and use consistent naming.
@author Jan Wielemaker
@author Wouter Beek
@see https://github.com/SWI-Prolog/packages-semweb/wiki/Proposal-for-Semweb-library-redesign
@version 2016
*/
:- multifile
in_ground_type_hook/3, % +Type, +Input, -Lexical:atom
out_type_hook/3, % +Type, -Output, +Lexical:atom
invalid_lexical_form_hook/3. % +Type, +Lexical, -Prolog
:- meta_predicate
parse_partial_xml(3,+,-).
:- rdf_meta
rdf(r,r,o),
rdf(r,r,o,r),
rdf_assert(r,r,o),
rdf_assert(r,r,o,r),
rdf_has(r,r,o),
rdf_has(r,r,o,-),
rdf_update(r,r,o,t),
rdf_update(r,r,o,r,t),
rdf_reachable(r,r,o),
rdf_reachable(r,r,o,+,-),
rdf_retractall(r,r,o),
rdf_retractall(r,r,o,r),
{}(t),
rdf_where(t),
rdf_canonical_literal(o,-),
rdf_lexical_form(o,-),
rdf_compare(-,o,o),
rdf_iri(r),
rdf_is_iri(r),
rdf_is_literal(o),
rdf_is_name(o),
rdf_is_object(o),
rdf_is_predicate(r),
rdf_is_subject(r),
rdf_is_term(o),
rdf_term(o),
rdf_literal(o),
rdf_name(o),
rdf_object(o),
rdf_estimate_complexity(r,r,o,-),
rdf_assert_list(t,r),
rdf_assert_list(t,r,r),
rdf_last(r,o),
rdf_list(r),
rdf_list(r,-),
rdf_length(r,-),
rdf_member(o,r),
rdf_nextto(o,o),
rdf_nth0(?,r,o),
rdf_nth1(?,r,o),
rdf_retract_list(r).
%! rdf(?S, ?P, ?O) is nondet.
%! rdf(?S, ?P, ?O, ?G) is nondet.
%
% True if an RDF triple <S,P,O> exists, optionally in the graph G.
% The object O is either a resource (atom) or one of the terms
% listed below. The described types apply for the case where O is
% unbound. If O is instantiated it is converted according to the
% rules described with rdf_assert/3.
%
% Triples consist of the following three terms:
%
% - Blank nodes are encoded by atoms that start with `_:`.
% - IRIs appear in two notations:
% - Full IRIs are encoded by atoms that do not start with
% `_:`. Specifically, an IRI term is not required to follow
% the IRI standard grammar.
% - Abbreviated IRI notation that allows IRI prefix aliases
% that are registered by rdf_register_prefix/[2,3] to be
% used. Their notation is `Alias:Local`, where Alias and
% Local are atoms. Each abbreviated IRI is expanded by the
% system to a full IRI.
% - Literals appear in two notations:
% - String@Lang
% A language-tagged string, where String is a Prolog string
% and Lang is an atom.
% - Value^^Type
% A type qualified literal. For unknown types, Value is a
% Prolog string. If type is known, the Prolog representations
% from the table below are used.
%
% | **Datatype IRI** | **Prolog term** |
% |:----------------------|:--------------------------------|
% | xsd:float | float |
% | xsd:double | float |
% | xsd:decimal | float (1) |
% | xsd:integer | integer |
% | XSD integer sub-types | integer |
% | xsd:boolean | `true` or `false` |
% | xsd:date | date(Y,M,D) |
% | xsd:dateTime | date_time(Y,M,D,HH,MM,SS) (2,3) |
% | xsd:gDay | integer |
% | xsd:gMonth | integer |
% | xsd:gMonthDay | month_day(M,D) |
% | xsd:gYear | integer |
% | xsd:gYearMonth | year_month(Y,M) |
% | xsd:time | time(HH,MM,SS) (2) |
%
% Notes:
%
% (1) The current implementation of `xsd:decimal` values
% as floats is formally incorrect. Future versions
% of SWI-Prolog may introduce decimal as a subtype
% of rational.
%
% (2) `SS` fields denote the number of seconds. This can
% either be an integer or a float.
%
% (3) The `date_time` structure can have a 7th field that
% denotes the timezone offset *in seconds* as an
% integer.
%
% In addition, a _ground_ object value is translated into a
% properly typed RDF literal using rdf_canonical_literal/2.
%
% There is a fine distinction in how duplicate statements are
% handled in rdf/[3,4]: backtracking over rdf/3 will never return
% duplicate triples that appear in multiple graphs. rdf/4 will
% return such duplicate triples, because their graph term differs.
%
% @arg S is the subject term. It is either a blank node or IRI.
% @arg P is the predicate term. It is always an IRI.
% @arg O is the object term. It is either a literal, a blank
% node or IRI (except for `true` and `false` that denote the
% values of datatype XSD boolean).
% @arg G is the graph term. It is always an IRI.
%
% @see [Triple pattern querying](http://www.w3.org/TR/sparql11-query/#sparqlTriplePatterns)
% @see xsd_number_string/2 and xsd_time_string/3 are used to
% convert between lexical representations and Prolog terms.
rdf(S,P,O) :-
pre_object(O,O0),
rdf_db:rdf(S,P,O0),
post_object(O,O0).
rdf(S,P,O,G) :-
pre_object(O,O0),
pre_graph(G,G0),
rdf_db:rdf(S,P,O0,G0),
post_graph(G, G0),
post_object(O,O0).
%! rdf_has(?S, ?P, ?O) is nondet.
%! rdf_has(?S, ?P, ?O, -RealP) is nondet.
%
% Similar to rdf/3 and rdf/4, but P matches all predicates that
% are defined as an rdfs:subPropertyOf of P. This predicate also
% recognises the predicate properties `inverse_of` and
% `symmetric`. See rdf_set_predicate/2.
rdf_has(S,P,O) :-
pre_object(O,O0),
rdf_db:rdf_has(S,P,O0),
post_object(O,O0).
rdf_has(S,P,O,RealP) :-
pre_object(O,O0),
rdf_db:rdf_has(S,P,O0,RealP),
post_object(O,O0).
%! rdf_update(+S, +P, +O, ++Action) is det.
%! rdf_update(+S, +P, +O, +G, ++Action) is det.
%
% Replaces one of the three fields on the matching triples
% depending on Action:
%
% * subject(Resource)
% Changes the first field of the triple.
% * predicate(Resource)
% Changes the second field of the triple.
% * object(Object)
% Changes the last field of the triple to the given resource or
% literal(Value).
% * graph(Graph)
% Moves the triple from its current named graph to Graph.
% This only works with rdf_update/4 and will throw an error when
% used with rdf_update/3.
%
% The argument matching the action must be ground. If this
% argument is equivalent to the current value, no action is
% performed. Otherwise, the requested action is performed on all
% matching triples. For example, all resources typed `rdfs:Class`
% can be changed to `owl:Class` using
%
% ```
% ?- rdf_update(_, rdf:type, rdfs:'Class',
% object(owl:'Class')).
% ```
%
% @error instantiation_error if Action or the matching argument is
% not ground.
% @error domain_error(rdf_update_action, Action) if Action is not
% one of the above terms.
rdf_update(S, P, O, Action) :-
rdf_update(S, P, O, _, Action).
rdf_update(S, P, O, G, Action) :-
must_be(ground, Action),
( update_column(Action, S,P,O,G, On)
-> must_be(ground, On),
arg(1, Action, Old),
( On == Old
-> true
; rdf_transaction(rdf_update_(S, P, O, G, Action), update)
)
; domain_error(rdf_update_action, Action)
).
update_column(subject(_), S,_,_,_, S).
update_column(predicate(_), _,P,_,_, P).
update_column(object(_), _,_,O,_, O).
update_column(graph(_), _,_,_,G, G).
rdf_update_(S1, P, O, G, subject(S2)) :-
!,
forall(rdf(S1, P, O, G),
( rdf_retractall(S1, P, O, G),
rdf_assert(S2, P, O, G)
)).
rdf_update_(S, P1, O, G, predicate(P2)) :-
!,
forall(rdf(S, P1, O, G),
( rdf_retractall(S, P1, O, G),
rdf_assert(S, P2, O, G)
)).
rdf_update_(S, P, O1, G, object(O2)) :-
!,
forall(rdf(S, P, O1, G),
( rdf_retractall(S, P, O1, G),
rdf_assert(S, P, O2, G)
)).
rdf_update_(S, P, O, G1, graph(G2)) :-
!,
forall(rdf(S, P, O, G1),
( rdf_retractall(S, P, O, G1),
rdf_assert(S, P, O, G2)
)).
%! rdf_reachable(?S, +P, ?O) is nondet.
%! rdf_reachable(?S, +P, ?O, +MaxD, -D) is nondet.
%
% True when O can be reached from S using the transitive closure
% of P. The predicate uses (the internals of) rdf_has/3 and thus
% matches both rdfs:subPropertyOf and the `inverse_of` and
% `symmetric` predicate properties. The version rdf_reachable/5
% maximizes the steps considered and returns the number of steps
% taken.
%
% If both S and O are given, these predicates are `semidet`. The
% number of steps D is minimal because the implementation uses
% _breadth first_ search.
rdf_reachable(S,P,O) :-
pre_object(O,O0),
rdf_db:rdf_reachable(S,P,O0),
post_object(O,O0).
rdf_reachable(S,P,O,MaxD,D) :-
pre_object(O,O0),
rdf_db:rdf_reachable(S,P,O0,MaxD,D),
post_object(O,O0).
%! rdf_assert(+S, +P, +O) is det.
%! rdf_assert(+S, +P, +O, +G) is det.
%
% Assert a new triple. If O is a literal, certain Prolog terms are
% translated to typed RDF literals. These conversions are
% described with rdf_canonical_literal/2.
%
% If a type is provided using Value^^Type syntax, additional
% conversions are performed. All types accept either an atom or
% Prolog string holding a valid RDF lexical value for the type and
% xsd:float and xsd:double accept a Prolog integer.
rdf_assert(S,P,O) :-
rdf_default_graph(G),
rdf_assert(S,P,O,G).
rdf_assert(S,P,O,G) :-
must_be(ground, O),
pre_ground_object(O,O0),
rdf_db:rdf_assert(S,P,O0,G).
%! rdf_retractall(?S, ?P, ?O) is nondet.
%! rdf_retractall(?S, ?P, ?O, ?G) is nondet.
%
% Remove all matching triples from the database. Matching is
% performed using the same rules as rdf/3. The call does not
% instantiate any of its arguments.
rdf_retractall(S,P,O) :-
pre_object(O,O0),
rdf_db:rdf_retractall(S,P,O0).
rdf_retractall(S,P,O,G) :-
pre_object(O,O0),
pre_graph(G,G0),
rdf_db:rdf_retractall(S,P,O0,G0).
%! rdf_compare(-Diff, +Left, +Right) is det.
%
% True if the RDF terms Left and Right are ordered according to
% the comparison operator Diff. The ordering is defines as:
%
% - Literal < BNode < IRI
% - For literals
% - Numeric < non-numeric
% - Numeric literals are ordered by value. If both are
% equal, floats are ordered before integers.
% - Other data types are ordered lexicographically.
% - BNodes and IRIs are ordered lexicographically.
%
% Note that this ordering is a complete ordering of RDF terms that
% is consistent with the partial ordering defined by SPARQL.
%
% @arg Diff is one of `<`, `=` or `>`
rdf_compare(Diff, Left, Right) :-
pre_ground_object(Left, Left0),
pre_ground_object(Right, Right0),
rdf_db:rdf_compare(Diff, Left0, Right0).
%! {}(+Where) is semidet.
%! rdf_where(+Where) is semidet.
%
% Formulate constraints on RDF terms, notably literals. These are
% intended to be used as illustrated below. RDF constraints are
% pure: they may be placed before, after or inside a graph pattern
% and, provided the code contains no _commit_ operations (!, ->),
% the semantics of the goal remains the same. Preferably,
% constraints are placed _before_ the graph pattern as they often
% help the RDF database to exploit its literal indexes. In the
% example below, the database can choose between using the subject
% and/or predicate hash or the ordered literal table.
%
% ==
% { Date >= "2000-01-01"^^xsd:date },
% rdf(S, P, Date)
% ==
%
% The following constraints are currently defined:
%
% - >, >=, ==, =<, <
% The comparison operators are defined between numbers (of any
% recognised type), typed literals of the same type and
% langStrings of the same language.
% - prefix(String, Pattern)
% - substring(String, Pattern)
% - word(String, Pattern)
% - like(String, Pattern)
% - icase(String, Pattern)
% Text matching operators that act on both typed literals
% and langStrings.
% - lang_matches(Term, Pattern)
% Demands a full RDF term (Text@Lang) or a plain `Lang` term
% to match the language pattern Pattern.
%
% The predicates rdf_where/1 and {}/1 are identical. The
% rdf_where/1 variant is provided to avoid ambiguity in
% applications where {}/1 is used for other purposes. Note that it
% is also possible to write `rdf11:{...}`.
{}(Where) :-
rdf_where(Where).
rdf_where(Var) :-
var(Var),
!,
instantiation_error(Var).
rdf_where((A,B)) :-
!,
rdf_where(A),
rdf_where(B).
rdf_where(Constraint) :-
rdf_constraint(Constraint, Goal),
!,
call(Goal).
rdf_where(Constraint) :-
existence_error(rdf_constraint, Constraint).
% Comparison operators
rdf_constraint(Term >= Value,
add_value_constraint(Term, >=, Value)).
rdf_constraint(Term > Value,
add_value_constraint(Term, >, Value)).
rdf_constraint(Term == Value,
add_value_constraint(Term, ==, Value)).
rdf_constraint(Term < Value,
add_value_constraint(Term, <, Value)).
rdf_constraint(Term =< Value,
add_value_constraint(Term, =<, Value)).
% String selection
rdf_constraint(prefix(Term, Pattern),
add_text_constraint(Term, prefix(PatternA))) :-
atom_string(PatternA, Pattern).
rdf_constraint(substring(Term, Pattern),
add_text_constraint(Term, substring(PatternA))) :-
atom_string(PatternA, Pattern).
rdf_constraint(word(Term, Pattern),
add_text_constraint(Term, word(PatternA))) :-
atom_string(PatternA, Pattern).
rdf_constraint(like(Term, Pattern),
add_text_constraint(Term, like(PatternA))) :-
atom_string(PatternA, Pattern).
rdf_constraint(icase(Term, Pattern),
add_text_constraint(Term, icase(PatternA))) :-
atom_string(PatternA, Pattern).
% Lang selection
rdf_constraint(lang_matches(Term, Pattern),
add_lang_constraint(Term, lang_matches(Pattern))).
add_text_constraint(Var, Cond) :-
var(Var),
!,
( get_attr(Var, rdf11, Cond0)
-> put_attr(Var, rdf11, [Cond|Cond0])
; put_attr(Var, rdf11, [Cond])
).
add_text_constraint(Text^^_Type, Cond) :-
!,
add_text_constraint(Text, Cond).
add_text_constraint(Text@_Lang, Cond) :-
!,
add_text_constraint(Text, Cond).
add_text_constraint(Var, Cond) :-
eval_condition(Cond, Var).
%! add_lang_constraint(?Term, +Constraint)
%
% Add a constraint on the language of a literal
add_lang_constraint(Var, Constraint) :-
var(Var),
!,
( get_attr(Var, rdf11, Cond0)
-> put_attr(Var, rdf11, [Constraint|Cond0])
; put_attr(Var, rdf11, [Constraint])
).
add_lang_constraint(_Text@Lang, Constraint) :-
!,
add_lang_constraint(Lang, Constraint).
add_lang_constraint(_Text^^_Type, _Constraint) :-
!,
fail.
add_lang_constraint(Term, Constraint) :-
eval_condition(Constraint, Term).
%! add_value_constraint(?Term, +Constraint, +Value)
%
% Apply a value constraint to the RDF Term.
add_value_constraint(Term, Constraint, ValueIn) :-
constraint_literal_value(ValueIn, Value),
add_value_constraint_cann(Value, Constraint, Term).
constraint_literal_value(Value, Value^^_Type) :-
number(Value),
!.
constraint_literal_value(Value, Literal) :-
rdf_canonical_literal(Value, Literal).
add_value_constraint_cann(RefVal^^Type, Constraint, Term) :-
var(Term), var(Type),
!,
add_text_constraint(Term, value(Constraint, RefVal, Type)).
add_value_constraint_cann(RefVal^^Type, Constraint, Val^^Type2) :-
!,
Type = Type2,
add_text_constraint(Val, value(Constraint, RefVal, Type)).
add_value_constraint_cann(RefVal@Lang, Constraint, Val@Lang) :-
!,
add_text_constraint(Val, value(Constraint, RefVal, lang(Lang))).
add_value_constraint_cann(RefVal^^Type, Constraint, Val) :-
!,
ground(Val),
Val \= _@_,
eval_condition(value(Constraint, RefVal, Type), Val).
put_cond(Var, []) :-
!,
del_attr(Var, rdf11).
put_cond(Var, List) :-
put_attr(Var, rdf11, List).
eval_condition(Cond, Literal) :-
text_condition(Cond),
!,
text_of(Literal, Text),
text_condition(Cond, Text).
eval_condition(Cond, Literal) :-
lang_condition(Cond),
!,
lang_of(Literal, Lang),
lang_condition(Cond, Lang).
eval_condition(value(Comp, Ref, _Type), Value) :-
( number(Ref)
-> number(Value),
compare_numeric(Comp, Ref, Value)
; compare_std(Comp, Ref, Value)
).
compare_numeric(<, Ref, Value) :- Value < Ref.
compare_numeric(=<, Ref, Value) :- Value =< Ref.
compare_numeric(==, Ref, Value) :- Value =:= Ref.
compare_numeric(>=, Ref, Value) :- Value >= Ref.
compare_numeric( >, Ref, Value) :- Value > Ref.
compare_std(<, Ref, Value) :- Value @< Ref.
compare_std(=<, Ref, Value) :- Value @=< Ref.
compare_std(==, Ref, Value) :- Value == Ref.
compare_std(>=, Ref, Value) :- Value @>= Ref.
compare_std( >, Ref, Value) :- Value @> Ref.
text_condition(prefix(_)).
text_condition(substring(_)).
text_condition(word(_)).
text_condition(like(_)).
text_condition(icase(_)).
text_of(Literal, Text) :-
atomic(Literal),
!,
Text = Literal.
text_of(Text@_Lang, Text).
text_of(Text^^_Type, Text).
text_condition(prefix(Pattern), Text) :-
rdf_match_label(prefix, Pattern, Text).
text_condition(substring(Pattern), Text) :-
rdf_match_label(substring, Pattern, Text).
text_condition(word(Pattern), Text) :-
rdf_match_label(word, Pattern, Text).
text_condition(like(Pattern), Text) :-
rdf_match_label(like, Pattern, Text).
text_condition(icase(Pattern), Text) :-
rdf_match_label(icase, Pattern, Text).
lang_condition(lang_matches(_)).
lang_of(_Text@Lang0, Lang) :-
!,
Lang = Lang0.
lang_of(Lang, Lang) :-
atom(Lang).
lang_condition(lang_matches(Pattern), Lang) :-
rdf_db:lang_matches(Lang, Pattern).
%! literal_condition(+Object, -Cond) is semidet.
%
% True when some of the constraints on Object can be translated
% into an equivalent query of the form literal(Cond, _Value).
% Translated constraints are removed from object.
literal_condition(Object, Cond) :-
var(Object),
!,
get_attr(Object, rdf11, Cond0),
best_literal_cond(Cond0, Cond, Rest),
put_cond(Object, Rest).
literal_condition(Text@_Lang, Cond) :-
get_attr(Text, rdf11, Cond0),
!,
best_literal_cond(Cond0, Cond, Rest),
put_cond(Text, Rest).
literal_condition(Text^^_Type, Cond) :-
get_attr(Text, rdf11, Cond0),
best_literal_cond(Cond0, Cond, Rest),
put_cond(Text, Rest).
%! best_literal_cond(+Conditions, -Best, -Rest) is semidet.
%
% Extract the constraints that can be translated into the _Search_
% of literal(Search, Value).
%
% @tbd Select the best rather than the first.
best_literal_cond(Conditions, Best, Rest) :-
sort(Conditions, Unique),
best_literal_cond2(Unique, Best, Rest).
best_literal_cond2(Conds, Best, Rest) :-
select(Cond, Conds, Rest0),
rdf10_cond(Cond, Best, Rest0, Rest),
!.
rdf10_cond(value(=<, URef, UType), Cond, Rest0, Rest) :-
( select(value(>=, LRef, LType), Rest0, Rest)
-> true
; memberchk(value(>, LRef, LType), Rest0)
-> Rest = Rest0
),
!,
in_constaint_type(LType, SLType, LRef, LRef0),
in_constaint_type(UType, SUType, URef, URef0),
Cond = between(type(SLType, LRef0), type(SUType, URef0)).
rdf10_cond(value(<, URef, UType), Cond, Rest0, Rest) :-
( select(value(>=, LRef, LType), Rest0, Rest1)
-> true
; memberchk(value(>, LRef, LType), Rest0)
-> Rest1 = Rest0
),
!,
Rest = [value(<, URef, UType)|Rest1],
in_constaint_type(LType, SLType, LRef, LRef0),
in_constaint_type(UType, SUType, URef, URef0),
Cond = between(type(SLType, LRef0), type(SUType, URef0)).
rdf10_cond(value(Cmp, Ref, Type), Pattern, Rest, Rest) :-
!,
rdf10_compare(Cmp, Ref, Type, Pattern).
rdf10_cond(lang_matches(_), _, _, _) :- !, fail.
rdf10_cond(Cond, Cond, Rest, Rest).
rdf10_compare(Cmp, Ref, Type, Pattern) :-
nonvar(Type), Type = lang(Lang),
!,
atom_string(Ref0, Ref),
rdf10_lang_cond(Cmp, Ref0, Lang, Pattern).
rdf10_compare(Cmp, Ref, Type, Pattern) :-
in_constaint_type(Type, SType, Ref, Ref0),
rdf10_type_cond(Cmp, Ref0, SType, Pattern).
rdf10_lang_cond( <, Ref, Lang, lt(lang(Lang,Ref))).
rdf10_lang_cond(=<, Ref, Lang, le(lang(Lang,Ref))).
rdf10_lang_cond(==, Ref, Lang, eq(lang(Lang,Ref))).
rdf10_lang_cond(>=, Ref, Lang, ge(lang(Lang,Ref))).
rdf10_lang_cond(>, Ref, Lang, gt(lang(Lang,Ref))).
rdf10_type_cond( <, Ref, Type, lt(type(Type,Ref))).
rdf10_type_cond(=<, Ref, Type, le(type(Type,Ref))).
rdf10_type_cond(==, Ref, Type, eq(type(Type,Ref))).
rdf10_type_cond(>=, Ref, Type, ge(type(Type,Ref))).
rdf10_type_cond( >, Ref, Type, gt(type(Type,Ref))).
%! in_constaint_type(?Type, -SType, ++Val, -Val0)
in_constaint_type(Type, SType, Val, Val0) :-
nonvar(Type), ground(Val),
!,
SType = Type,
in_ground_type(Type, Val, Val0).
in_constaint_type(Type, SType, Val, Val0) :-
var(Type), number(Val),
!,
( integer(Val)
-> rdf_equal(SType, xsd:integer),
in_ground_type(xsd:integer, Val, Val0)
; float(Val)
-> rdf_equal(SType, xsd:double),
in_ground_type(xsd:double, Val, Val0)
; assertion(fail)
).
%! literal_class(+Term, -Class)
%
% Classify Term as literal and if possible as lang or typed
% literal on the basis of the constraints that apply to it.
literal_class(Term, Class) :-
get_attr(Term, rdf11, Conds),
select(Cond, Conds, Rest),
lang_condition(Cond),
!,
Term = Text@Lang,
put_attr(Lang, rdf11, [Cond]),
put_cond(Text, Rest),
( var(Text)
-> true
; atom_string(Text2, Text)
),
Class = lang(Lang, Text2).
%! attr_unify_hook(+AttributeValue, +Value)
attr_unify_hook(Cond, Value) :-
get_attr(Value, rdf11, Cond2),
!,
append(Cond, Cond2, CondJ),
sort(CondJ, Unique),
put_cond(Value, Unique).
attr_unify_hook(Cond, Text^^_Type) :-
var(Text),
!,
put_cond(Text, Cond).
attr_unify_hook(Cond, Text@Lang) :-
var(Text), var(Lang),
!,
partition(lang_condition, Cond, LangCond, TextCond),
put_cond(Text, TextCond),
put_cond(Lang, LangCond).
attr_unify_hook(Cond, Value) :-
sort(Cond, Unique),
propagate_conditions(Unique, Value).
propagate_conditions([], _).
propagate_conditions([H|T], Val) :-
propagate_condition(H, Val),
propagate_conditions(T, Val).
propagate_condition(value(Comp, Ref, Type), Value) :-
!,
( Value = Plain^^VType
-> VType = Type
; Plain = Value
),
cond_compare(Comp, Ref, Plain).
propagate_condition(lang_matches(Pattern), Value) :-
!,
( Value = _@Lang
-> true
; Lang = Value
),
rdf_db:lang_matches(Lang, Pattern).
propagate_condition(Cond, Value) :-
Cond =.. [Name|Args],
Constraint =.. [Name,Value|Args],
rdf_constraint(Constraint, Continuation),
call(Continuation).
cond_compare(>, Ref, Value) :- Value @> Ref.
cond_compare(>=, Ref, Value) :- Value @>= Ref.
cond_compare(==, Ref, Value) :- Value == Ref.
cond_compare(=<, Ref, Value) :- Value @=< Ref.
cond_compare( <, Ref, Value) :- Value @< Ref.
%! rdf_default_graph(-Graph) is det.
%! rdf_default_graph(-Old, +New) is det.
%
% Query/set the notion of the default graph. The notion of the
% default graph is local to a thread. Threads created inherit the
% default graph from their creator. See set_prolog_flag/2.
:- create_prolog_flag(rdf_default_graph, default,
[ type(atom),
keep(true)
]).
rdf_default_graph(Graph) :-
current_prolog_flag(rdf_default_graph, Graph).
rdf_default_graph(Old, New) :-
current_prolog_flag(rdf_default_graph, Old),
( New == Old
-> true
; set_prolog_flag(rdf_default_graph, New)
).
pre_graph(G, _G0) :-
var(G),
!.
pre_graph(G, G) :-
atom(G),
!.
pre_graph(G, _) :-
type_error(rdf_graph, G).
post_graph(G, G0:_) :-
!,
G = G0.
post_graph(G, G).
pre_object(Literal, literal(Cond, Value)) :-
literal_condition(Literal, Cond),
!,
debug(literal_index, 'Search literal using ~p', [literal(Cond, Value)]),
literal_value0(Literal, Value).
pre_object(Literal, literal(Value)) :-
literal_class(Literal, Value),
!,
debug(literal_index, 'Search literal using ~p', [literal(Value)]).
pre_object(Var, _Var) :-
var(Var),
!.
pre_object(Atom, URI) :-
atom(Atom),
\+ boolean(Atom),
!,
URI = Atom.
pre_object(Val@Lang, literal(lang(Lang, Val0))) :-
!,
in_lang_string(Val, Val0).
pre_object(Val^^Type, literal(Literal)) :-
!,
in_type(Type, Val, Type0, Val0),
( var(Type0), var(Val0)
-> true
; Literal = type(Type0, Val0)
).
pre_object(Obj, Val0) :-
ground(Obj),
!,
pre_ground_object(Obj, Val0).
pre_object(Obj, _) :-
type_error(rdf_object, Obj).
literal_value0(Var, _) :-
var(Var),
!.
literal_value0(_ @Lang, lang(Lang, _)).
literal_value0(_^^Type, type(Type, _)).
%! pre_ground_object(+Object, -RDF) is det.
%
% Convert between a Prolog value and an RDF value for rdf_assert/3
% and friends. Auto-conversion:
%
% - Integer
% Converted to Integer^^xsd:integer
% - Float
% Converted to Float^^xsd:double
% - String
% Converted to String^^xsd:string
% - true
% Converted to true^^xsd:boolean
% - false
% Converted to false^^xsd:boolean
% - date(Y,M,D)
% Converted to date(Y,M,D)^^xsd:date
% - date_time(Y,M,D,HH,MM,SS)
% Converted to date_time(Y,M,D,HH,MM,SS)^^xsd:dateTime
% - date_time(Y,M,D,HH,MM,SS,TZ)
% Converted to date_time(Y,M,D,HH,MM,SS,TZ)^^xsd:dateTime
% - month_day(M,D)
% Converted to month_day(M,D)^^xsd:gMonthDay
% - year_month(Y,M)
% Converted to year_month(Y,M)^^xsd:gYearMonth
% - time(HH,MM,SS)
% Converted to time(HH,MM,SS)^^xsd:time
% - Text@Lang
% Converted to Text@Lang. Uses canonical (lowercase) lang.
% Text is converted into an atom.
% - Value^^Type
% Typed conversion. The translation of Value depends on
% Type:
% - Numeric types
% - Boolean
% - Date types
% - Atom
% All atoms except for `true` and `false` are considered
% URIs.
:- rdf_meta
pre_ground_object(+, o).
% Interpret Prolog integer as xsd:integer.
pre_ground_object(Int, Object) :-
integer(Int),
!,
rdf_equal(Object, literal(type(xsd:integer, Atom))),
atom_number(Atom, Int).
% Interpret Prolog floating-point value as xsd:double.
pre_ground_object(Float, Object) :-
float(Float),
!,
rdf_equal(Object, literal(type(xsd:double, Atom))),
xsd_number_string(Float, String),
atom_string(Atom, String).
% Interpret SWI string as xsd:string.
pre_ground_object(String, Object) :-
string(String),
!,
rdf_equal(Object, literal(type(xsd:string, Atom))),
atom_string(Atom, String).
% Interpret `false' and `true' as the Boolean values.
pre_ground_object(false, literal(type(xsd:boolean, false))) :- !.
pre_ground_object(true, literal(type(xsd:boolean, true))) :- !.
% Interpret date(Y,M,D) as xsd:date,
% date_time(Y,M,D,HH,MM,SS) as xsd:dateTime,
% date_time(Y,M,D,HH,MM,SS,TZ) as xsd:dateTime,
% month_day(M,D) as xsd:gMonthDay,
% year_month(Y,M) as xsd:gYearMonth, and
% time(HH,MM,SS) as xsd:time.
pre_ground_object(Term, literal(type(Type, Atom))) :-
xsd_date_time_term(Term),
!,
xsd_time_string(Term, Type, Atom).
pre_ground_object(Val@Lang, literal(lang(Lang0, Val0))) :-
!,
downcase_atom(Lang, Lang0),
in_lang_string(Val, Val0).
pre_ground_object(Val^^Type, literal(type(Type0, Val0))) :-
!,
in_type(Type, Val, Type0, Val0).
pre_ground_object(Atom, URI) :-
atom(Atom),
!,
URI = Atom.
%pre_ground_object(NS:Local, URI) :- % still leaves S and P.
% atom(NS), atom(Local), !,
% rdf_global_id(NS:Local, URI).
pre_ground_object(literal(Lit0), literal(Lit)) :-
old_literal(Lit0, Lit),
!.
pre_ground_object(Value, _) :-
type_error(rdf_object, Value).
xsd_date_time_term(date(_,_,_)).
xsd_date_time_term(date_time(_,_,_,_,_,_)).
xsd_date_time_term(date_time(_,_,_,_,_,_,_)).
xsd_date_time_term(month_day(_,_)).
xsd_date_time_term(year_month(_,_)).
xsd_date_time_term(time(_,_,_)).
old_literal(Lit0, Lit) :-
old_literal(Lit0),
!,
Lit = Lit0.
old_literal(Atom, Lit) :-
atom(Atom),
rdf_equal(xsd:string, XSDString),
Lit = type(XSDString, Atom).
old_literal(type(Type, Value)) :-
atom(Type), atom(Value).
old_literal(lang(Lang, Value)) :-
atom(Lang), atom(Value).
in_lang_string(Val, Val0) :-
atomic(Val),
!,
atom_string(Val0, Val).
in_lang_string(_, _).
in_type(Type, Val, Type, Val0) :-
nonvar(Type), ground(Val),
!,
in_ground_type(Type, Val, Val0).
in_type(VarType, Val, VarType, Val0) :-
ground(Val),
\+ catch(xsd_number_string(_, Val), _, fail),
!,
atom_string(Val0, Val).
in_type(_, _, _, _).
:- rdf_meta
in_ground_type(r,?,?),
in_date_component(r, +, +, -).
%! in_ground_type(+Type, +Input, -Lexical:atom) is det.
%
% Translate the Prolog date Input according to Type into its RDF
% lexical form. The lecical form is represented as an atom. In
% future versions this is likely to become a string.
in_ground_type(Type, Input, Lex) :-
\+ string(Input),
in_ground_type_hook(Type, Input, Lex),
!.
in_ground_type(IntType, Val, Val0) :-
xsd_numerical(IntType, Domain, PrologType),
!,
in_number(PrologType, Domain, IntType, Val, Val0).
in_ground_type(xsd:boolean, Val, Val0) :-
!,
( in_boolean(Val, Val0)
-> true
; type_error(rdf_boolean, Val)
).
in_ground_type(rdf:langString, _Val0, _) :-
!,
domain_error(rdf_data_type, rdf:langString).
in_ground_type(DateTimeType, Val, Val0) :-
xsd_date_time_type(DateTimeType),
!,
in_date_time(DateTimeType, Val, Val0).
in_ground_type(rdf:'XMLLiteral', Val, Val0) :-
!,
in_xml_literal(xml, Val, Val0).
in_ground_type(rdf:'HTML', Val, Val0) :-
!,
in_xml_literal(html, Val, Val0).
in_ground_type(_Unknown, Val, Val0) :-
atom_string(Val0, Val).
%! in_date_time(+Type, +Input, -Lexical) is det.
%
% Accepts either a term as accepted by xsd_time_string/3 or a
% valid string for the corresponding XSD type.
:- rdf_meta
in_date_time(r,+,-).
in_date_time(Type, Text, Text0) :-
atom(Text),
!,
xsd_time_string(_, Type, Text),
Text0 = Text.
in_date_time(Type, Text, Text0) :-
string(Text),
!,
xsd_time_string(_, Type, Text),
atom_string(Text0, Text).
in_date_time(xsd:dateTime, Stamp, Text0) :-
number(Stamp),
!,
format_time(atom(Text0), '%FT%T%:z', Stamp).
in_date_time(Type, Term, Text0) :-
!,
xsd_time_string(Term, Type, String),
atom_string(Text0, String).
%! in_boolean(?NonCanonical, ?Canonical)
%
% True when Canonical is the canonical boolean for NonCanonical.
in_boolean(true, true).
in_boolean(false, false).
in_boolean("true", true).
in_boolean("false", false).
in_boolean(1, true).
in_boolean(0, false).
boolean(false).
boolean(true).
%! in_number(+PrologType, +Domain, +XSDType, +Value, -Lexical)
%
% Lexical is the lexical representation for Value.
%
% @error type_error(PrologType, Value)
% @error domain_error(XSDType, Value)
in_number(integer, Domain, XSDType, Val, Val0) :-
integer(Val),
!,
check_integer_domain(Domain, XSDType, Val),
atom_number(Val0, Val).
in_number(integer, Domain, XSDType, Val, Val0) :-
atomic(Val),
atom_number(Val, Num),
integer(Num),
!,
check_integer_domain(Domain, XSDType, Num),
atom_number(Val0, Num).
in_number(double, _Domain, _, Val, Val0) :-
number(Val),
!,
ValF is float(Val),
xsd_number_string(ValF, ValS),
atom_string(Val0, ValS).
in_number(double, _Domain, _, Val, Val0) :-
atomic(Val),
xsd_number_string(Num, Val),
ValF is float(Num),
!,
xsd_number_string(ValF, ValS),
atom_string(Val0, ValS).
in_number(PrologType, _, _, Val, _) :-
type_error(PrologType, Val).
check_integer_domain(PLType, _, Val) :-
is_of_type(PLType, Val),
!.
check_integer_domain(_, XSDType, Val) :-
domain_error(XSDType, Val).
error:has_type(nonpos, T):-
integer(T),
T =< 0.
%check_integer_domain(between(Low, High), XSDType, Val) :-
% ( between(Low, High, Val)
% -> true
% ; domain_error(XSDType, Val)
% ).
%check_integer_domain(integer, _, _).
%! xsd_numerical(?URI, ?TypeCheck, ?PrologType)
:- rdf_meta
xsd_numerical(r, ?, ?).
xsd_numerical(xsd:byte, between(-128,127), integer).
xsd_numerical(xsd:double, float, double).
xsd_numerical(xsd:decimal, float, double).
xsd_numerical(xsd:float, float, double).
xsd_numerical(xsd:int, between(-2147483648,2147483647), integer).
xsd_numerical(xsd:integer, integer, integer).
xsd_numerical(xsd:long, between(-9223372036854775808,
9223372036854775807), integer).
xsd_numerical(xsd:negativeInteger, negative_integer, integer).
xsd_numerical(xsd:nonNegativeInteger, nonneg, integer).
xsd_numerical(xsd:nonPositiveInteger, nonpos, integer).
xsd_numerical(xsd:positiveInteger, positive_integer, integer).
xsd_numerical(xsd:short, between(-32768,32767), integer).
xsd_numerical(xsd:unsignedByte, between(0,255), integer).
xsd_numerical(xsd:unsignedInt, between(0,4294967295), integer).
xsd_numerical(xsd:unsignedLong, between(0,18446744073709551615), integer).
xsd_numerical(xsd:unsignedShort, between(0,65535), integer).
%! xsd_date_time_type(?URI)
%
% True when URI is an XSD date or time type.
:- rdf_meta
xsd_date_time_type(r).
xsd_date_time_type(xsd:date).
xsd_date_time_type(xsd:dateTime).
xsd_date_time_type(xsd:gDay).
xsd_date_time_type(xsd:gMonth).
xsd_date_time_type(xsd:gMonthDay).
xsd_date_time_type(xsd:gYear).
xsd_date_time_type(xsd:gYearMonth).
xsd_date_time_type(xsd:time).
%! in_xml_literal(+Type, +Val, -Val0) is det.
%
% Translate an XMLLiteral or HTML literal to its canonical textual
% representation. Input is either text or a Prolog XML DOM.
%
% @tbd Deal with partial content?
in_xml_literal(Type, Val, Val0) :-
xml_is_dom(Val),
!,
write_xml_literal(Type, Val, Val0).
in_xml_literal(xml, Val, Val0) :-
parse_partial_xml(load_xml, Val, DOM),
write_xml_literal(xml, DOM, Val0).
in_xml_literal(html, Val, Val0) :-
parse_partial_xml(load_html, Val, DOM),
write_xml_literal(html, DOM, Val0).
parse_partial_xml(Parser, Val, DOM) :-
setup_call_cleanup(
new_memory_file(MF),
( setup_call_cleanup(
open_memory_file(MF, write, Out),
format(Out, "<xml>~w</xml>", [Val]),
close(Out)),
setup_call_cleanup(
open_memory_file(MF, read, In),
call(Parser, stream(In), [element(xml, _, DOM)], []),
close(In))
),
free_memory_file(MF)).
write_xml_literal(xml, DOM, Text) :-
with_output_to(atom(Text),
xml_write_canonical(current_output, DOM, [])).
write_xml_literal(html, DOM, Text) :-
with_output_to(atom(Text),
html_write(current_output, DOM,
[ header(false),
layout(false)
])).
%! rdf_canonical_literal(++In, -Literal) is det.
%
% Transform a relaxed literal specification as allowed for
% rdf_assert/3 into its canonical form. The following Prolog terms
% are translated:
%
% | **Prolog Term** | **Datatype IRI** |
% |:------------------------------|:-----------------|
% | float | xsd:double |
% | integer | xsd:integer |
% | string | xsd:string |
% | `true` or `false` | xsd:boolean |
% | date(Y,M,D) | xsd:date |
% | date_time(Y,M,D,HH,MM,SS) | xsd:dateTime |
% | date_time(Y,M,D,HH,MM,SS,TZ) | xsd:dateTime |
% | month_day(M,D) | xsd:gMonthDay |
% | year_month(Y,M) | xsd:gYearMonth |
% | time(HH,MM,SS) | xsd:time |
%
% For example:
%
% ```
% ?- rdf_canonical_literal(42, X).
% X = 42^^'http://www.w3.org/2001/XMLSchema#integer'.
% ```
rdf_canonical_literal(In, Literal) :-
ground(In),
!,
pre_ground_object(In, DBTerm),
post_object(Literal, DBTerm).
rdf_canonical_literal(In, _) :-
must_be(ground, In).
%! rdf_lexical_form(++Literal, -Lexical:compound) is det.
%
% True when Lexical is the lexical form for the literal Literal.
% Lexical is of one of the forms below. The ntriples serialization
% is obtained by transforming String into a proper ntriples string
% using double quotes and escaping where needed and turning Type
% into a proper IRI reference.
%
% - String^^Type
% - String@Lang
% For example,
%
% ==
% ?- rdf_lexical_form(2.3^^xsd:double, L).
% L = "2.3E0"^^'http://www.w3.org/2001/XMLSchema#double'.
% ==
rdf_lexical_form(Literal, Lexical) :-
pre_ground_object(Literal, literal(Lit0)),
!,
text_of0(Lit0, Lexical).
rdf_lexical_form(Literal, _) :-
type_error(rdf_literal, Literal).
text_of0(type(TypeA, LexicalA), LexicalS^^TypeA) :-
atom_string(LexicalA, LexicalS).
text_of0(lang(LangA, LexicalA), LexicalS@LangA) :-
atom_string(LexicalA, LexicalS).
/*******************************
* POST PROCESSING *
*******************************/
:- rdf_meta
post_object(o,o),
out_type(r,-,+).
post_object(Val, _) :-
ground(Val),
!. % already specified and matched
post_object(URI, URI0) :-
atom(URI0),
!,
URI = URI0.
post_object(Val@Lang, literal(lang(Lang, Val0))) :-
nonvar(Lang), % lang(Lang,Text) returns var(Lang) if no lang
!,
atom_string(Val0, Val).
post_object(Val^^Type, literal(type(Type, Val0))) :-
!,
out_type(Type, Val, Val0).
post_object(Val^^xsd:string, literal(Plain)) :-
!,
atomic(Plain),
atom_string(Plain, Val).
post_object(Val@Lang, literal(_, lang(Lang, Val0))) :-
nonvar(Lang),
!,
atom_string(Val0, Val).
post_object(Val^^Type, literal(_, type(Type, Val0))) :-
!,
out_type(Type, Val, Val0).
post_object(Val^^xsd:string, literal(_, Plain)) :-
atomic(Plain),
atom_string(Plain, Val).
out_type(xsd:string, Val, Val0) :- % catches unbound type too
!,
atom_string(Val0, Val).
out_type(Type, Val, Val0) :-
out_type_hook(Type, Val, Val0),
!.
out_type(IntType, Val, Val0) :-
xsd_numerical(IntType, _Domain, _BasicType),
!,
xsd_number_string(Val, Val0).
out_type(DateTimeType, Val, Val0) :-
xsd_date_time_type(DateTimeType),
!,
out_date_time(DateTimeType, Val, Val0).
out_type(xsd:boolean, Val, Val0) :-
!,
Val = Val0.
out_type(rdf:'XMLLiteral', XML, DOM) :-
xml_is_dom(DOM),
!,
with_output_to(string(XML),
xml_write(DOM, [header(false)])).
out_type(_Unknown, Val, Val0) :-
atom_string(Val0, Val).
%! out_date_time(+DateTimeType, -Val, +Val0) is det.
%
% Translate an XSD lexical form for a date/time related datatype
% into the cannical form as defined by xsd_time_string/3.
out_date_time(Type, Prolog, Lexical) :-
catch(xsd_time_string(Prolog, Type, Lexical),
error(_,_),
invalid_lexical_form_hook(Type, Lexical, Prolog)).
%! invalid_lexical_form_hook(+Type, +Lexical, -Prolog)
%
% This hook is called if translation of the lexical form to the Prolog
% representation fails due to a syntax error. By default it is not
% defined, causing such invalid triples to be silently ignored.
/*******************************
* ENUMERATION *
*******************************/
%! rdf_term(?Term) is nondet.
%
% True if Term appears in the RDF database. Term is either an IRI,
% literal or blank node and may appear in any position of any
% triple. If Term is ground, it is pre-processed as the object
% argument of rdf_assert/3 and the predicate is _semidet_.
rdf_term(N) :-
ground(N),
!,
pre_object(N, N0),
visible_term(N0).
rdf_term(N) :-
gen_term(N).
gen_term(N) :-
resource(N),
visible_term(N).
gen_term(O) :- % performs double conversion!
rdf_literal(O),
(rdf(_,_,O) -> true).
%! rdf_literal(?Term) is nondet.
%
% True if Term is a known literal. If Term is ground, it is
% pre-processed as the object argument of rdf_assert/3 and the
% predicate is _semidet_.
rdf_literal(Term) :-
ground(Term),
!,
pre_ground_object(Term, Object),
(rdf_db:rdf(_,_,Object)->true).
rdf_literal(Term) :-
pre_object(Term,literal(Lit0)),
rdf_db:rdf_current_literal(Lit0),
(rdf_db:rdf(_,_,literal(Lit0))->true),
post_object(Term, literal(Lit0)).
%! rdf_bnode(?BNode) is nondet.
%
% True if BNode is a currently known blank node. The predicate is
% _semidet_ if BNode is ground.
rdf_bnode(BNode) :-
atom(BNode),
!,
current_bnode(BNode).
rdf_bnode(BNode) :-
rdf_db:rdf_resource(BNode),
current_bnode(BNode).
current_bnode(BNode) :-
rdf_is_bnode(BNode),
visible_node(BNode). % Assumes BNodes cannot be predicates
%! rdf_iri(?IRI) is nondet.
%
% True if IRI is a current IRI. The predicate is _semidet_ if IRI
% is ground.
rdf_iri(IRI) :-
atom(IRI),
!,
\+ rdf_is_bnode(IRI),
visible_term(IRI).
rdf_iri(IRI) :-
resource(IRI),
\+ rdf_is_bnode(IRI),
visible_term(IRI).
%! rdf_name(?Name) is nondet.
%
% True if Name is a current IRI or literal. The predicate is
% _semidet_ if Name is ground.
rdf_name(Name) :-
atom(Name), \+ boolean(Name),
!,
\+ rdf_is_bnode(Name),
visible_term(Name).
rdf_name(Name) :-
ground(Name),
!,
pre_ground_object(Name, Name0),
(rdf_db:rdf(_,_,Name0)->true).
rdf_name(Name) :-
rdf_iri(Name).
rdf_name(Name) :-
rdf_literal(Name).
%! rdf_subject(?S) is nondet.
%
% True when S is a currently known _subject_, i.e. it appears in
% the subject position of some visible triple. The predicate is
% _semidet_ if S is ground.
%! rdf_predicate(?P) is nondet.
%
% True when P is a currently known predicate, i.e. it appears in
% the predicate position of some visible triple. The predicate is
% _semidet_ if P is ground.
rdf_predicate(P) :-
atom(P),
!,
(rdf(_,P,_) -> true).
rdf_predicate(P) :-
rdf_db:rdf_current_predicate(P),
(rdf(_,P,_) -> true).
%! rdf_object(?O) is nondet.
%
% True when O is a currently known object, i.e. it appears in the
% object position of some visible triple. If Term is ground, it is
% pre-processed as the object argument of rdf_assert/3 and the
% predicate is _semidet_.
rdf_object(O) :-
ground(O),
!,
( atom(O), \+ boolean(O)
-> (rdf_db:rdf(_,_,O) -> true)
; rdf_literal(O)
).
rdf_object(O) :-
rdf_db:rdf_resource(O),
(rdf_db:rdf(_,_,O) -> true).
rdf_object(O) :-
rdf_literal(O).
%! rdf_node(?T) is nondet.
%
% True when T appears in the subject or object position of a known
% triple, i.e., is a node in the RDF graph.
rdf_node(N) :-
var(N),
!,
gen_node(N).
rdf_node(N) :-
pre_ground_object(N, N0),
visible_node(N0).
gen_node(N) :-
rdf_db:rdf_resource(N),
visible_node(N).
gen_node(O) :- % performs double conversion!
rdf_literal(O),
(rdf(_,_,O) -> true).
%! resource(?R)
%
% True if R is a node that is not a literal. Note that RDF-DB does
% not necessarily include predicates in the set of resources. Also
% note that the resource may not really exist or be visible.
resource(R) :-
var(R),
!,
gen_resource(R).
resource(R) :-
rdf_db:rdf_resource(R),
!.
resource(R) :-
rdf_db:rdf_current_predicate(R),
!.
gen_resource(R) :-
rdf_db:rdf_resource(R).
gen_resource(R) :-
rdf_db:rdf_current_predicate(R),
\+ rdf_db:rdf_resource(R).
visible_node(Term) :-
atom(Term),
!,
( rdf_db:rdf(Term,_,_)
; rdf_db:rdf(_,_,Term)
),
!.
visible_node(Term) :-
rdf_db:rdf(_,_,Term).
visible_term(Term) :-
atom(Term),
!,
( rdf_db:rdf(Term,_,_)
; rdf_db:rdf(_,Term,_)
; rdf_db:rdf(_,_,Term)
),
!.
visible_term(Term) :-
rdf_db:rdf(_,_,Term).
%! rdf_create_bnode(--BNode)
%
% Create a new BNode. A blank node is an atom starting with
% =|_:|=. Blank nodes generated by this predicate are of the form
% =|_:genid|= followed by a unique integer.
rdf_create_bnode(BNode) :-
var(BNode),
!,
rdf_db:rdf_bnode(BNode).
rdf_create_bnode(BNode) :-
uninstantiation_error(BNode).
/*******************************
* TYPE CHECKING *
*******************************/
%! rdf_is_iri(@IRI) is semidet.
%
% True if IRI is an RDF IRI term.
%
% For performance reasons, this does not check for compliance to
% the syntax defined in [[RFC
% 3987][http://www.ietf.org/rfc/rfc3987.txt]]. This checks
% whether the term is (1) an atom and (2) not a blank node
% identifier.
%
% Success of this goal does not imply that the IRI is present in
% the database (see rdf_iri/1 for that).
rdf_is_iri(IRI) :-
atom(IRI),
\+ rdf_is_bnode(IRI).
%! rdf_is_bnode(@Term) is semidet.
%
% True if Term is an RDF blank node identifier.
%
% A blank node is represented by an atom that starts with
% =|_:|=.
%
% Success of this goal does not imply that the blank node is
% present in the database (see rdf_bnode/1 for that).
%
% For backwards compatibility, atoms that are represented with
% an atom that starts with =|__|= are also considered to be a
% blank node.
%! rdf_is_literal(@Term) is semidet.
%
% True if Term is an RDF literal term.
%
% An RDF literal term is of the form `String@LanguageTag` or
% `Value^^Datatype`.
%
% Success of this goal does not imply that the literal is
% well-formed or that it is present in the database (see
% rdf_literal/1 for that).
rdf_is_literal(Literal) :-
literal_form(Literal),
!,
ground(Literal).
literal_form(_@_).
literal_form(_^^_).
%! rdf_is_name(@Term) is semidet.
%
% True if Term is an RDF Name, i.e., an IRI or literal.
%
% Success of this goal does not imply that the name is
% well-formed or that it is present in the database (see
% rdf_name/1 for that).
rdf_is_name(T) :- rdf_is_iri(T), !.
rdf_is_name(T) :- rdf_is_literal(T).
%! rdf_is_object(@Term) is semidet.
%
% True if Term can appear in the object position of a triple.
%
% Success of this goal does not imply that the object term in
% well-formed or that it is present in the database (see
% rdf_object/1 for that).
%
% Since any RDF term can appear in the object position, this is
% equaivalent to rdf_is_term/1.
rdf_is_object(T) :- rdf_is_subject(T), !.
rdf_is_object(T) :- rdf_is_literal(T).
%! rdf_is_predicate(@Term) is semidet.
%
% True if Term can appear in the predicate position of a triple.
%
% Success of this goal does not imply that the predicate term is
% present in the database (see rdf_predicate/1 for that).
%
% Since only IRIs can appear in the predicate position, this is
% equivalent to rdf_is_iri/1.
rdf_is_predicate(T) :- rdf_is_iri(T).
%! rdf_is_subject(@Term) is semidet.
%
% True if Term can appear in the subject position of a triple.
%
% Only blank nodes and IRIs can appear in the subject position.
%
% Success of this goal does not imply that the subject term is
% present in the database (see rdf_subject/1 for that).
%
% Since blank nodes are represented by atoms that start with
% `_:` and an IRIs are atoms as well, this is equivalent to
% atom(Term).
rdf_is_subject(T) :- atom(T).
%! rdf_is_term(@Term) is semidet.
%
% True if Term can be used as an RDF term, i.e., if Term is
% either an IRI, a blank node or an RDF literal.
%
% Success of this goal does not imply that the RDF term is
% present in the database (see rdf_term/1 for that).
rdf_is_term(N) :- rdf_is_subject(N), !.
rdf_is_term(N) :- rdf_is_literal(N).
/*******************************
* COLLECTIONS *
*******************************/
%! rdf_list(?RDFTerm) is semidet.
%
% True if RDFTerm is a proper RDF list. This implies that every
% node in the list has an `rdf:first` and `rdf:rest` property and
% the list ends in `rdf:nil`.
%
% If RDFTerm is unbound, RDFTerm is bound to each _maximal_ RDF
% list. An RDF list is _maximal_ if there is no triple rdf(_,
% rdf:rest, RDFList).
rdf_list(L) :-
var(L),
!,
rdf_has(L, rdf:first, _),
\+ rdf_has(_, rdf:rest, L),
rdf_list_g(L).
rdf_list(L) :-
rdf_list_g(L),
!.
rdf_list_g(rdf:nil) :- !.
rdf_list_g(L) :-
once(rdf_has(L, rdf:first, _)),
rdf_has(L, rdf:rest, Rest),
( rdf_equal(rdf:nil, Rest)
-> true
; rdf_list_g(Rest)
).
%! rdf_list(+RDFList, -PrologList) is det.
%
% True when PrologList represents the rdf:first objects for all
% cells in RDFList. Note that this can be non-deterministic if
% cells have multiple rdf:first or rdf:rest triples.
rdf_list(RDFList, Prolog) :-
rdf_is_subject(RDFList),
!,
rdf_list_to_prolog(RDFList, Prolog).
rdf_list(RDFList, _Prolog) :-
type_error(rdf_subject, RDFList).
:- rdf_meta
rdf_list_to_prolog(r,-).
rdf_list_to_prolog(rdf:nil, Prolog) :-
!,
Prolog = [].
rdf_list_to_prolog(RDF, [H|T2]) :-
( rdf_has(RDF, rdf:first, H0),
rdf_has(RDF, rdf:rest, T1)
*-> H = H0,
rdf_list_to_prolog(T1, T2)
; type_error(rdf_list, RDF)
).
%! rdf_length(+RDFList, -Length:nonneg) is nondet.
%
% True when Length is the number of cells in RDFList. Note that a
% list cell may have multiple rdf:rest triples, which makes this
% predicate non-deterministic. This predicate does not check
% whether the list cells have associated values (rdf:first). The
% list must end in rdf:nil.
rdf_length(RDFList, Len) :-
rdf_is_subject(RDFList),
!,
rdf_length(RDFList, 0, Len).
:- rdf_meta
rdf_length(r,+,-).
rdf_length(rdf:nil, Len, Len) :- !.
rdf_length(RDF, Len0, Len) :-
( rdf_has(RDF, rdf:rest, T)
*-> Len1 is Len0+1,
rdf_length(T, Len1, Len)
; type_error(rdf_list, RDF)
).
%! rdf_member(?Member, +RDFList) is nondet.
%
% True when Member is a member of RDFList
rdf_member(M, L) :-
ground(M),
!,
( rdf_member2(M, L)
-> true
).
rdf_member(M, L) :-
rdf_member2(M, L).
rdf_member2(M, L) :-
rdf_has(L, rdf:first, M).
rdf_member2(M, L) :-
rdf_has(L, rdf:rest, L1),
rdf_member2(M, L1).
%! rdf_nextto(?X, ?Y) is nondet.
%! rdf_nextto(?X, ?Y, ?RdfList) is nondet.
%
% True if Y directly follows X in RdfList.
rdf_nextto(X, Y) :-
distinct(X-Y, rdf_nextto(X, Y, _)).
rdf_nextto(X, Y, L) :-
var(X), ground(Y),
!,
rdf_nextto(Y, X, L).
rdf_nextto(X, Y, L) :-
rdf_has(L, rdf:first, X),
rdf_has(L, rdf:rest, T),
rdf_has(T, rdf:first, Y).
%! rdf_nth0(?Index, +RDFList, ?X) is nondet.
%! rdf_nth1(?Index, +RDFList, ?X) is nondet.
%
% True when X is the Index-th element (0-based or 1-based) of
% RDFList. This predicate is deterministic if Index is given and
% the list has no multiple rdf:first or rdf:rest values.
rdf_nth0(I, L, X) :-
rdf_nth(0, I, L, X).
rdf_nth1(I, L, X) :-
rdf_nth(1, I, L, X).
rdf_nth(Offset, I, L, X) :-
rdf_is_subject(L),
!,
( var(I)
-> true
; must_be(nonneg, I)
),
rdf_nth_(I, Offset, L, X).
rdf_nth(_, _, L, _) :-
type_error(rdf_subject, L).
rdf_nth_(I, I0, L, X) :-
( I0 == I
-> !
; I0 = I
),
rdf_has(L, rdf:first, X).
rdf_nth_(I, I0, L, X) :-
rdf_has(L, rdf:rest, T),
I1 is I0+1,
rdf_nth_(I, I1, T, X).
%! rdf_last(+RDFList, -Last) is det.
%
% True when Last is the last element of RDFList. Note that if the
% last cell has multiple rdf:first triples, this predicate becomes
% nondet.
rdf_last(L, Last) :-
rdf_is_subject(L),
!,
rdf_has(L, rdf:rest, T),
( rdf_equal(T, rdf:nil)
-> rdf_has(L, rdf:first, Last)
; rdf_last(T, Last)
).
rdf_last(L, _) :-
type_error(rdf_subject, L).
%! rdf_estimate_complexity(?S, ?P, ?O, -Estimate) is det.
rdf_estimate_complexity(S, P, O, Estimate) :-
pre_object(O,O0),
rdf_db:rdf_estimate_complexity(S,P,O0,Estimate).
%! rdf_assert_list(+PrologList, ?RDFList) is det.
%! rdf_assert_list(+PrologList, ?RDFList, +Graph) is det.
%
% Create an RDF list from the given Prolog List. PrologList must
% be a proper Prolog list and all members of the list must be
% acceptable as object for rdf_assert/3. If RDFList is unbound and
% PrologList is not empty, rdf_create_bnode/1 is used to create
% RDFList.
rdf_assert_list(Prolog, RDF) :-
rdf_default_graph(G),
rdf_assert_list(Prolog, RDF, G).
rdf_assert_list(Prolog, RDF, G) :-
must_be(list, Prolog),
rdf_transaction(rdf_assert_list_(Prolog, RDF, G)).
rdf_assert_list_([], Nil, _) :-
rdf_equal(rdf:nil, Nil).
rdf_assert_list_([H|T], L2, G) :-
(var(L2) -> rdf_create_bnode(L2) ; true),
rdf_assert(L2, rdf:type, rdf:'List', G),
rdf_assert(L2, rdf:first, H, G),
( T == []
-> rdf_assert(L2, rdf:rest, rdf:nil, G)
; rdf_create_bnode(T2),
rdf_assert(L2, rdf:rest, T2, G),
rdf_assert_list_(T, T2, G)
).
%! rdf_retract_list(+RDFList) is det.
%
% Retract the rdf:first, rdf:rest and rdf:type=rdf:'List' triples
% from all nodes reachable through rdf:rest. Note that other
% triples that exist on the nodes are left untouched.
rdf_retract_list(L) :-
rdf_is_subject(L),
!,
rdf_transaction(rdf_retract_list_(L)).
rdf_retract_list(L) :-
type_error(rdf_subject, L).
:- rdf_meta
rdf_retract_list_(r).
rdf_retract_list_(rdf:nil) :- !.
rdf_retract_list_(L) :-
rdf_retractall(L, rdf:first, _),
forall(rdf_has(L, rdf:rest, L1),
rdf_retract_list_(L1)),
rdf_retractall(L, rdf:rest, _),
rdf_retractall(L, rdf:type, rdf:'List').
|