aboutsummaryrefslogtreecommitdiffstats
path: root/phpBB/phpbb/search/fulltext_native.php
blob: 63ac242ea2c79b9931380a3b03d34b6a4fa5b2a0 (plain)
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
2060
2061
2062
2063
2064
2065
2066
<?php
/**
*
* This file is part of the phpBB Forum Software package.
*
* @copyright (c) phpBB Limited <https://www.phpbb.com>
* @license GNU General Public License, version 2 (GPL-2.0)
*
* For full copyright and license information, please see
* the docs/CREDITS.txt file.
*
*/

namespace phpbb\search;

/**
* phpBB's own db driven fulltext search, version 2
*/
class fulltext_native extends \phpbb\search\base
{
	const UTF8_HANGUL_FIRST = "\xEA\xB0\x80";
	const UTF8_HANGUL_LAST = "\xED\x9E\xA3";
	const UTF8_CJK_FIRST = "\xE4\xB8\x80";
	const UTF8_CJK_LAST = "\xE9\xBE\xBB";
	const UTF8_CJK_B_FIRST = "\xF0\xA0\x80\x80";
	const UTF8_CJK_B_LAST = "\xF0\xAA\x9B\x96";

	/**
	 * Associative array holding index stats
	 * @var array
	 */
	protected $stats = array();

	/**
	 * Associative array stores the min and max word length to be searched
	 * @var array
	 */
	protected $word_length = array();

	/**
	 * Contains tidied search query.
	 * Operators are prefixed in search query and common words excluded
	 * @var string
	 */
	protected $search_query;

	/**
	 * Contains common words.
	 * Common words are words with length less/more than min/max length
	 * @var array
	 */
	protected $common_words = array();

	/**
	 * Post ids of posts containing words that are to be included
	 * @var array
	 */
	protected $must_contain_ids = array();

	/**
	 * Post ids of posts containing words that should not be included
	 * @var array
	 */
	protected $must_not_contain_ids = array();

	/**
	 * Post ids of posts containing at least one word that needs to be excluded
	 * @var array
	 */
	protected $must_exclude_one_ids = array();

	/**
	 * Relative path to board root
	 * @var string
	 */
	protected $phpbb_root_path;

	/**
	 * PHP Extension
	 * @var string
	 */
	protected $php_ext;

	/**
	 * Config object
	 * @var \phpbb\config\config
	 */
	protected $config;

	/**
	 * Database connection
	 * @var \phpbb\db\driver\driver_interface
	 */
	protected $db;

	/**
	 * phpBB event dispatcher object
	 * @var \phpbb\event\dispatcher_interface
	 */
	protected $phpbb_dispatcher;

	/**
	 * User object
	 * @var \phpbb\user
	 */
	protected $user;

	/**
	* Initialises the fulltext_native search backend with min/max word length
	*
	* @param	boolean|string	&$error	is passed by reference and should either be set to false on success or an error message on failure
	* @param	string	$phpbb_root_path	phpBB root path
	* @param	string	$phpEx	PHP file extension
	* @param	\phpbb\auth\auth	$auth	Auth object
	* @param	\phpbb\config\config	$config	Config object
	* @param	\phpbb\db\driver\driver_interface	$db	Database object
	* @param	\phpbb\user	$user	User object
	* @param	\phpbb\event\dispatcher_interface	$phpbb_dispatcher	Event dispatcher object
	*/
	public function __construct(&$error, $phpbb_root_path, $phpEx, $auth, $config, $db, $user, $phpbb_dispatcher)
	{
		$this->phpbb_root_path = $phpbb_root_path;
		$this->php_ext = $phpEx;
		$this->config = $config;
		$this->db = $db;
		$this->phpbb_dispatcher = $phpbb_dispatcher;
		$this->user = $user;

		$this->word_length = array('min' => (int) $this->config['fulltext_native_min_chars'], 'max' => (int) $this->config['fulltext_native_max_chars']);

		/**
		* Load the UTF tools
		*/
		if (!function_exists('utf8_decode_ncr'))
		{
			include($this->phpbb_root_path . 'includes/utf/utf_tools.' . $this->php_ext);
		}

		$error = false;
	}

	/**
	* Returns the name of this search backend to be displayed to administrators
	*
	* @return string Name
	*/
	public function get_name()
	{
		return 'phpBB Native Fulltext';
	}

	/**
	 * Returns the search_query
	 *
	 * @return string search query
	 */
	public function get_search_query()
	{
		return $this->search_query;
	}

	/**
	 * Returns the common_words array
	 *
	 * @return array common words that are ignored by search backend
	 */
	public function get_common_words()
	{
		return $this->common_words;
	}

	/**
	 * Returns the word_length array
	 *
	 * @return array min and max word length for searching
	 */
	public function get_word_length()
	{
		return $this->word_length;
	}

	/**
	* This function fills $this->search_query with the cleaned user search query
	*
	* If $terms is 'any' then the words will be extracted from the search query
	* and combined with | inside brackets. They will afterwards be treated like
	* an standard search query.
	*
	* Then it analyses the query and fills the internal arrays $must_not_contain_ids,
	* $must_contain_ids and $must_exclude_one_ids which are later used by keyword_search()
	*
	* @param	string	$keywords	contains the search query string as entered by the user
	* @param	string	$terms		is either 'all' (use search query as entered, default words to 'must be contained in post')
	* 	or 'any' (find all posts containing at least one of the given words)
	* @return	boolean				false if no valid keywords were found and otherwise true
	*/
	public function split_keywords($keywords, $terms)
	{
		$tokens = '+-|()* ';

		$keywords = trim($this->cleanup($keywords, $tokens));

		// allow word|word|word without brackets
		if ((strpos($keywords, ' ') === false) && (strpos($keywords, '|') !== false) && (strpos($keywords, '(') === false))
		{
			$keywords = '(' . $keywords . ')';
		}

		$open_bracket = $space = false;
		for ($i = 0, $n = strlen($keywords); $i < $n; $i++)
		{
			if ($open_bracket !== false)
			{
				switch ($keywords[$i])
				{
					case ')':
						if ($open_bracket + 1 == $i)
						{
							$keywords[$i - 1] = '|';
							$keywords[$i] = '|';
						}
						$open_bracket = false;
					break;
					case '(':
						$keywords[$i] = '|';
					break;
					case '+':
					case '-':
					case ' ':
						$keywords[$i] = '|';
					break;
					case '*':
						// $i can never be 0 here since $open_bracket is initialised to false
						if (strpos($tokens, $keywords[$i - 1]) !== false && ($i + 1 === $n || strpos($tokens, $keywords[$i + 1]) !== false))
						{
							$keywords[$i] = '|';
						}
					break;
				}
			}
			else
			{
				switch ($keywords[$i])
				{
					case ')':
						$keywords[$i] = ' ';
					break;
					case '(':
						$open_bracket = $i;
						$space = false;
					break;
					case '|':
						$keywords[$i] = ' ';
					break;
					case '-':
					case '+':
						$space = $keywords[$i];
					break;
					case ' ':
						if ($space !== false)
						{
							$keywords[$i] = $space;
						}
					break;
					default:
						$space = false;
				}
			}
		}

		if ($open_bracket !== false)
		{
			$keywords .= ')';
		}

		$match = array(
			'#  +#',
			'#\|\|+#',
			'#(\+|\-)(?:\+|\-)+#',
			'#\(\|#',
			'#\|\)#',
		);
		$replace = array(
			' ',
			'|',
			'$1',
			'(',
			')',
		);

		$keywords = preg_replace($match, $replace, $keywords);
		$num_keywords = count(explode(' ', $keywords));

		// We limit the number of allowed keywords to minimize load on the database
		if ($this->config['max_num_search_keywords'] && $num_keywords > $this->config['max_num_search_keywords'])
		{
			trigger_error($this->user->lang('MAX_NUM_SEARCH_KEYWORDS_REFINE', (int) $this->config['max_num_search_keywords'], $num_keywords));
		}

		// $keywords input format: each word separated by a space, words in a bracket are not separated

		// the user wants to search for any word, convert the search query
		if ($terms == 'any')
		{
			$words = array();

			preg_match_all('#([^\\s+\\-|()]+)(?:$|[\\s+\\-|()])#u', $keywords, $words);
			if (count($words[1]))
			{
				$keywords = '(' . implode('|', $words[1]) . ')';
			}
		}

		// Remove non trailing wildcards from each word to prevent a full table scan (it's now using the database index)
		$match = '#\*(?!$|\s)#';
		$replace = '$1';
		$keywords = preg_replace($match, $replace, $keywords);

		// Only allow one wildcard in the search query to limit the database load
		$match = '#\*#';
		$replace = '$1';
		$count_wildcards = substr_count($keywords, '*');

		// Reverse the string to remove all wildcards except the first one
		$keywords = strrev(preg_replace($match, $replace, strrev($keywords), $count_wildcards - 1));
		unset($count_wildcards);

		// set the search_query which is shown to the user
		$this->search_query = $keywords;

		$exact_words = array();
		preg_match_all('#([^\\s+\\-|()]+)(?:$|[\\s+\\-|()])#u', $keywords, $exact_words);
		$exact_words = $exact_words[1];

		$common_ids = $words = array();

		if (count($exact_words))
		{
			$sql = 'SELECT word_id, word_text, word_common
				FROM ' . SEARCH_WORDLIST_TABLE . '
				WHERE ' . $this->db->sql_in_set('word_text', $exact_words) . '
				ORDER BY word_count ASC';
			$result = $this->db->sql_query($sql);

			// store an array of words and ids, remove common words
			while ($row = $this->db->sql_fetchrow($result))
			{
				if ($row['word_common'])
				{
					$this->common_words[] = $row['word_text'];
					$common_ids[$row['word_text']] = (int) $row['word_id'];
					continue;
				}

				$words[$row['word_text']] = (int) $row['word_id'];
			}
			$this->db->sql_freeresult($result);
		}

		// Handle +, - without preceding whitespace character
		$match		= array('#(\S)\+#', '#(\S)-#');
		$replace	= array('$1 +', '$1 +');

		$keywords = preg_replace($match, $replace, $keywords);

		// now analyse the search query, first split it using the spaces
		$query = explode(' ', $keywords);

		$this->must_contain_ids = array();
		$this->must_not_contain_ids = array();
		$this->must_exclude_one_ids = array();

		foreach ($query as $word)
		{
			if (empty($word))
			{
				continue;
			}

			// words which should not be included
			if ($word[0] == '-')
			{
				$word = substr($word, 1);

				// a group of which at least one may not be in the resulting posts
				if ($word[0] == '(')
				{
					$word = array_unique(explode('|', substr($word, 1, -1)));
					$mode = 'must_exclude_one';
				}
				// one word which should not be in the resulting posts
				else
				{
					$mode = 'must_not_contain';
				}
				$ignore_no_id = true;
			}
			// words which have to be included
			else
			{
				// no prefix is the same as a +prefix
				if ($word[0] == '+')
				{
					$word = substr($word, 1);
				}

				// a group of words of which at least one word should be in every resulting post
				if ($word[0] == '(')
				{
					$word = array_unique(explode('|', substr($word, 1, -1)));
				}
				$ignore_no_id = false;
				$mode = 'must_contain';
			}

			if (empty($word))
			{
				continue;
			}

			// if this is an array of words then retrieve an id for each
			if (is_array($word))
			{
				$non_common_words = array();
				$id_words = array();
				foreach ($word as $i => $word_part)
				{
					if (strpos($word_part, '*') !== false)
					{
						$len = utf8_strlen(str_replace('*', '', $word_part));
						if ($len >= $this->word_length['min'] && $len <= $this->word_length['max'])
						{
							$id_words[] = '\'' . $this->db->sql_escape(str_replace('*', '%', $word_part)) . '\'';
							$non_common_words[] = $word_part;
						}
						else
						{
							$this->common_words[] = $word_part;
						}
					}
					else if (isset($words[$word_part]))
					{
						$id_words[] = $words[$word_part];
						$non_common_words[] = $word_part;
					}
					else
					{
						$len = utf8_strlen($word_part);
						if ($len < $this->word_length['min'] || $len > $this->word_length['max'])
						{
							$this->common_words[] = $word_part;
						}
					}
				}
				if (count($id_words))
				{
					sort($id_words);
					if (count($id_words) > 1)
					{
						$this->{$mode . '_ids'}[] = $id_words;
					}
					else
					{
						$mode = ($mode == 'must_exclude_one') ? 'must_not_contain' : $mode;
						$this->{$mode . '_ids'}[] = $id_words[0];
					}
				}
				// throw an error if we shall not ignore unexistant words
				else if (!$ignore_no_id && count($non_common_words))
				{
					trigger_error(sprintf($this->user->lang['WORDS_IN_NO_POST'], implode($this->user->lang['COMMA_SEPARATOR'], $non_common_words)));
				}
				unset($non_common_words);
			}
			// else we only need one id
			else if (($wildcard = strpos($word, '*') !== false) || isset($words[$word]))
			{
				if ($wildcard)
				{
					$len = utf8_strlen(str_replace('*', '', $word));
					if ($len >= $this->word_length['min'] && $len <= $this->word_length['max'])
					{
						$this->{$mode . '_ids'}[] = '\'' . $this->db->sql_escape(str_replace('*', '%', $word)) . '\'';
					}
					else
					{
						$this->common_words[] = $word;
					}
				}
				else
				{
					$this->{$mode . '_ids'}[] = $words[$word];
				}
			}
			else
			{
				if (!isset($common_ids[$word]))
				{
					$len = utf8_strlen($word);
					if ($len < $this->word_length['min'] || $len > $this->word_length['max'])
					{
						$this->common_words[] = $word;
					}
				}
			}
		}

		// Return true if all words are not common words
		if (count($exact_words) - count($this->common_words) > 0)
		{
			return true;
		}
		return false;
	}

	/**
	* Performs a search on keywords depending on display specific params. You have to run split_keywords() first
	*
	* @param	string		$type				contains either posts or topics depending on what should be searched for
	* @param	string		$fields				contains either titleonly (topic titles should be searched), msgonly (only message bodies should be searched), firstpost (only subject and body of the first post should be searched) or all (all post bodies and subjects should be searched)
	* @param	string		$terms				is either 'all' (use query as entered, words without prefix should default to "have to be in field") or 'any' (ignore search query parts and just return all posts that contain any of the specified words)
	* @param	array		$sort_by_sql		contains SQL code for the ORDER BY part of a query
	* @param	string		$sort_key			is the key of $sort_by_sql for the selected sorting
	* @param	string		$sort_dir			is either a or d representing ASC and DESC
	* @param	string		$sort_days			specifies the maximum amount of days a post may be old
	* @param	array		$ex_fid_ary			specifies an array of forum ids which should not be searched
	* @param	string		$post_visibility	specifies which types of posts the user can view in which forums
	* @param	int			$topic_id			is set to 0 or a topic id, if it is not 0 then only posts in this topic should be searched
	* @param	array		$author_ary			an array of author ids if the author should be ignored during the search the array is empty
	* @param	string		$author_name		specifies the author match, when ANONYMOUS is also a search-match
	* @param	array		&$id_ary			passed by reference, to be filled with ids for the page specified by $start and $per_page, should be ordered
	* @param	int			$start				indicates the first index of the page
	* @param	int			$per_page			number of ids each page is supposed to contain
	* @return	boolean|int						total number of results
	*/
	public function keyword_search($type, $fields, $terms, $sort_by_sql, $sort_key, $sort_dir, $sort_days, $ex_fid_ary, $post_visibility, $topic_id, $author_ary, $author_name, &$id_ary, &$start, $per_page)
	{
		// No keywords? No posts.
		if (empty($this->search_query))
		{
			return false;
		}

		// we can't search for negatives only
		if (empty($this->must_contain_ids))
		{
			return false;
		}

		$must_contain_ids = $this->must_contain_ids;
		$must_not_contain_ids = $this->must_not_contain_ids;
		$must_exclude_one_ids = $this->must_exclude_one_ids;

		sort($must_contain_ids);
		sort($must_not_contain_ids);
		sort($must_exclude_one_ids);

		// generate a search_key from all the options to identify the results
		$search_key_array = array(
			serialize($must_contain_ids),
			serialize($must_not_contain_ids),
			serialize($must_exclude_one_ids),
			$type,
			$fields,
			$terms,
			$sort_days,
			$sort_key,
			$topic_id,
			implode(',', $ex_fid_ary),
			$post_visibility,
			implode(',', $author_ary),
			$author_name,
		);

		/**
		* Allow changing the search_key for cached results
		*
		* @event core.search_native_by_keyword_modify_search_key
		* @var	array	search_key_array	Array with search parameters to generate the search_key
		* @var	array	must_contain_ids	Array with post ids of posts containing words that are to be included
		* @var	array	must_not_contain_ids	Array with post ids of posts containing words that should not be included
		* @var	array	must_exclude_one_ids	Array with post ids of posts containing at least one word that needs to be excluded
		* @var	string	type				Searching type ('posts', 'topics')
		* @var	string	fields				Searching fields ('titleonly', 'msgonly', 'firstpost', 'all')
		* @var	string	terms				Searching terms ('all', 'any')
		* @var	int		sort_days			Time, in days, of the oldest possible post to list
		* @var	string	sort_key			The sort type used from the possible sort types
		* @var	int		topic_id			Limit the search to this topic_id only
		* @var	array	ex_fid_ary			Which forums not to search on
		* @var	string	post_visibility		Post visibility data
		* @var	array	author_ary			Array of user_id containing the users to filter the results to
		* @since 3.1.7-RC1
		*/
		$vars = array(
			'search_key_array',
			'must_contain_ids',
			'must_not_contain_ids',
			'must_exclude_one_ids',
			'type',
			'fields',
			'terms',
			'sort_days',
			'sort_key',
			'topic_id',
			'ex_fid_ary',
			'post_visibility',
			'author_ary',
		);
		extract($this->phpbb_dispatcher->trigger_event('core.search_native_by_keyword_modify_search_key', compact($vars)));

		$search_key = md5(implode('#', $search_key_array));

		// try reading the results from cache
		$total_results = 0;
		if ($this->obtain_ids($search_key, $total_results, $id_ary, $start, $per_page, $sort_dir) == SEARCH_RESULT_IN_CACHE)
		{
			return $total_results;
		}

		$id_ary = array();

		$sql_where = array();
		$m_num = 0;
		$w_num = 0;

		$sql_array = array(
			'SELECT'	=> ($type == 'posts') ? 'p.post_id' : 'p.topic_id',
			'FROM'		=> array(
				SEARCH_WORDMATCH_TABLE	=> array(),
				SEARCH_WORDLIST_TABLE	=> array(),
			),
			'LEFT_JOIN' => array(array(
				'FROM'	=> array(POSTS_TABLE => 'p'),
				'ON'	=> 'm0.post_id = p.post_id',
			)),
		);

		$title_match = '';
		$left_join_topics = false;
		$group_by = true;
		// Build some display specific sql strings
		switch ($fields)
		{
			case 'titleonly':
				$title_match = 'title_match = 1';
				$group_by = false;
			// no break
			case 'firstpost':
				$left_join_topics = true;
				$sql_where[] = 'p.post_id = t.topic_first_post_id';
			break;

			case 'msgonly':
				$title_match = 'title_match = 0';
				$group_by = false;
			break;
		}

		if ($type == 'topics')
		{
			$left_join_topics = true;
			$group_by = true;
		}

		/**
		* @todo Add a query optimizer (handle stuff like "+(4|3) +4")
		*/

		foreach ($this->must_contain_ids as $subquery)
		{
			if (is_array($subquery))
			{
				$group_by = true;

				$word_id_sql = array();
				$word_ids = array();
				foreach ($subquery as $id)
				{
					if (is_string($id))
					{
						$sql_array['LEFT_JOIN'][] = array(
							'FROM'	=> array(SEARCH_WORDLIST_TABLE => 'w' . $w_num),
							'ON'	=> "w$w_num.word_text LIKE $id"
						);
						$word_ids[] = "w$w_num.word_id";

						$w_num++;
					}
					else
					{
						$word_ids[] = $id;
					}
				}

				$sql_where[] = $this->db->sql_in_set("m$m_num.word_id", $word_ids);

				unset($word_id_sql);
				unset($word_ids);
			}
			else if (is_string($subquery))
			{
				$sql_array['FROM'][SEARCH_WORDLIST_TABLE][] = 'w' . $w_num;

				$sql_where[] = "w$w_num.word_text LIKE $subquery";
				$sql_where[] = "m$m_num.word_id = w$w_num.word_id";

				$group_by = true;
				$w_num++;
			}
			else
			{
				$sql_where[] = "m$m_num.word_id = $subquery";
			}

			$sql_array['FROM'][SEARCH_WORDMATCH_TABLE][] = 'm' . $m_num;

			if ($title_match)
			{
				$sql_where[] = "m$m_num.$title_match";
			}

			if ($m_num != 0)
			{
				$sql_where[] = "m$m_num.post_id = m0.post_id";
			}
			$m_num++;
		}

		foreach ($this->must_not_contain_ids as $key => $subquery)
		{
			if (is_string($subquery))
			{
				$sql_array['LEFT_JOIN'][] = array(
					'FROM'	=> array(SEARCH_WORDLIST_TABLE => 'w' . $w_num),
					'ON'	=> "w$w_num.word_text LIKE $subquery"
				);

				$this->must_not_contain_ids[$key] = "w$w_num.word_id";

				$group_by = true;
				$w_num++;
			}
		}

		if (count($this->must_not_contain_ids))
		{
			$sql_array['LEFT_JOIN'][] = array(
				'FROM'	=> array(SEARCH_WORDMATCH_TABLE => 'm' . $m_num),
				'ON'	=> $this->db->sql_in_set("m$m_num.word_id", $this->must_not_contain_ids) . (($title_match) ? " AND m$m_num.$title_match" : '') . " AND m$m_num.post_id = m0.post_id"
			);

			$sql_where[] = "m$m_num.word_id IS NULL";
			$m_num++;
		}

		foreach ($this->must_exclude_one_ids as $ids)
		{
			$is_null_joins = array();
			foreach ($ids as $id)
			{
				if (is_string($id))
				{
					$sql_array['LEFT_JOIN'][] = array(
						'FROM'	=> array(SEARCH_WORDLIST_TABLE => 'w' . $w_num),
						'ON'	=> "w$w_num.word_text LIKE $id"
					);
					$id = "w$w_num.word_id";

					$group_by = true;
					$w_num++;
				}

				$sql_array['LEFT_JOIN'][] = array(
					'FROM'	=> array(SEARCH_WORDMATCH_TABLE => 'm' . $m_num),
					'ON'	=> "m$m_num.word_id = $id AND m$m_num.post_id = m0.post_id" . (($title_match) ? " AND m$m_num.$title_match" : '')
				);
				$is_null_joins[] = "m$m_num.word_id IS NULL";

				$m_num++;
			}
			$sql_where[] = '(' . implode(' OR ', $is_null_joins) . ')';
		}

		$sql_where[] = $post_visibility;

		$search_query = $this->search_query;
		$must_exclude_one_ids = $this->must_exclude_one_ids;
		$must_not_contain_ids = $this->must_not_contain_ids;
		$must_contain_ids = $this->must_contain_ids;

		/**
		* Allow changing the query used for counting for posts using fulltext_native
		*
		* @event core.search_native_keywords_count_query_before
		* @var	string	search_query			The parsed keywords used for this search
		* @var	array	must_not_contain_ids	Ids that cannot be taken into account for the results
		* @var	array	must_exclude_one_ids	Ids that cannot be on the results
		* @var	array	must_contain_ids		Ids that must be on the results
		* @var	int		total_results			The previous result count for the format of the query
		*										Set to 0 to force a re-count
		* @var	array	sql_array				The data on how to search in the DB at this point
		* @var	bool	left_join_topics		Whether or not TOPICS_TABLE should be CROSS JOIN'ED
		* @var	array	author_ary				Array of user_id containing the users to filter the results to
		* @var	string	author_name				An extra username to search on (!empty(author_ary) must be true, to be relevant)
		* @var	array	ex_fid_ary				Which forums not to search on
		* @var	int		topic_id				Limit the search to this topic_id only
		* @var	string	sql_sort_table			Extra tables to include in the SQL query.
		*										Used in conjunction with sql_sort_join
		* @var	string	sql_sort_join			SQL conditions to join all the tables used together.
		*										Used in conjunction with sql_sort_table
		* @var	int		sort_days				Time, in days, of the oldest possible post to list
		* @var	string	sql_where				An array of the current WHERE clause conditions
		* @var	string	sql_match				Which columns to do the search on
		* @var	string	sql_match_where			Extra conditions to use to properly filter the matching process
		* @var	bool	group_by				Whether or not the SQL query requires a GROUP BY for the elements in the SELECT clause
		* @var	string	sort_by_sql				The possible predefined sort types
		* @var	string	sort_key				The sort type used from the possible sort types
		* @var	string	sort_dir				"a" for ASC or "d" dor DESC for the sort order used
		* @var	string	sql_sort				The result SQL when processing sort_by_sql + sort_key + sort_dir
		* @var	int		start					How many posts to skip in the search results (used for pagination)
		* @since 3.1.5-RC1
		*/
		$vars = array(
			'search_query',
			'must_not_contain_ids',
			'must_exclude_one_ids',
			'must_contain_ids',
			'total_results',
			'sql_array',
			'left_join_topics',
			'author_ary',
			'author_name',
			'ex_fid_ary',
			'topic_id',
			'sql_sort_table',
			'sql_sort_join',
			'sort_days',
			'sql_where',
			'sql_match',
			'sql_match_where',
			'group_by',
			'sort_by_sql',
			'sort_key',
			'sort_dir',
			'sql_sort',
			'start',
		);
		extract($this->phpbb_dispatcher->trigger_event('core.search_native_keywords_count_query_before', compact($vars)));

		if ($topic_id)
		{
			$sql_where[] = 'p.topic_id = ' . $topic_id;
		}

		if (count($author_ary))
		{
			if ($author_name)
			{
				// first one matches post of registered users, second one guests and deleted users
				$sql_author = '(' . $this->db->sql_in_set('p.poster_id', array_diff($author_ary, array(ANONYMOUS)), false, true) . ' OR p.post_username ' . $author_name . ')';
			}
			else
			{
				$sql_author = $this->db->sql_in_set('p.poster_id', $author_ary);
			}
			$sql_where[] = $sql_author;
		}

		if (count($ex_fid_ary))
		{
			$sql_where[] = $this->db->sql_in_set('p.forum_id', $ex_fid_ary, true);
		}

		if ($sort_days)
		{
			$sql_where[] = 'p.post_time >= ' . (time() - ($sort_days * 86400));
		}

		$sql_array['WHERE'] = implode(' AND ', $sql_where);

		$is_mysql = false;
		// if the total result count is not cached yet, retrieve it from the db
		if (!$total_results)
		{
			$sql = '';
			$sql_array_count = $sql_array;

			if ($left_join_topics)
			{
				$sql_array_count['LEFT_JOIN'][] = array(
					'FROM'	=> array(TOPICS_TABLE => 't'),
					'ON'	=> 'p.topic_id = t.topic_id'
				);
			}

			switch ($this->db->get_sql_layer())
			{
				case 'mysqli':

					// 3.x does not support SQL_CALC_FOUND_ROWS
					// $sql_array['SELECT'] = 'SQL_CALC_FOUND_ROWS ' . $sql_array['SELECT'];
					$is_mysql = true;

				break;

				case 'sqlite3':
					$sql_array_count['SELECT'] = ($type == 'posts') ? 'DISTINCT p.post_id' : 'DISTINCT p.topic_id';
					$sql = 'SELECT COUNT(' . (($type == 'posts') ? 'post_id' : 'topic_id') . ') as total_results
							FROM (' . $this->db->sql_build_query('SELECT', $sql_array_count) . ')';

				// no break

				default:
					$sql_array_count['SELECT'] = ($type == 'posts') ? 'COUNT(DISTINCT p.post_id) AS total_results' : 'COUNT(DISTINCT p.topic_id) AS total_results';
					$sql = (!$sql) ? $this->db->sql_build_query('SELECT', $sql_array_count) : $sql;

					$result = $this->db->sql_query($sql);
					$total_results = (int) $this->db->sql_fetchfield('total_results');
					$this->db->sql_freeresult($result);

					if (!$total_results)
					{
						return false;
					}
				break;
			}

			unset($sql_array_count, $sql);
		}

		// Build sql strings for sorting
		$sql_sort = $sort_by_sql[$sort_key] . (($sort_dir == 'a') ? ' ASC' : ' DESC');

		switch ($sql_sort[0])
		{
			case 'u':
				$sql_array['FROM'][USERS_TABLE] = 'u';
				$sql_where[] = 'u.user_id = p.poster_id ';
			break;

			case 't':
				$left_join_topics = true;
			break;

			case 'f':
				$sql_array['FROM'][FORUMS_TABLE] = 'f';
				$sql_where[] = 'f.forum_id = p.forum_id';
			break;
		}

		if ($left_join_topics)
		{
			$sql_array['LEFT_JOIN'][] = array(
				'FROM'	=> array(TOPICS_TABLE => 't'),
				'ON'	=> 'p.topic_id = t.topic_id'
			);
		}

		// if using mysql and the total result count is not calculated yet, get it from the db
		if (!$total_results && $is_mysql)
		{
			// Also count rows for the query as if there was not LIMIT. Add SQL_CALC_FOUND_ROWS to SQL
			$sql_array['SELECT'] = 'SQL_CALC_FOUND_ROWS ' . $sql_array['SELECT'];
		}

		$sql_array['WHERE'] = implode(' AND ', $sql_where);
		$sql_array['GROUP_BY'] = ($group_by) ? (($type == 'posts') ? 'p.post_id' : 'p.topic_id') . ', ' . $sort_by_sql[$sort_key] : '';
		$sql_array['ORDER_BY'] = $sql_sort;

		unset($sql_where, $sql_sort, $group_by);

		$sql = $this->db->sql_build_query('SELECT', $sql_array);
		$result = $this->db->sql_query_limit($sql, $this->config['search_block_size'], $start);

		while ($row = $this->db->sql_fetchrow($result))
		{
			$id_ary[] = (int) $row[(($type == 'posts') ? 'post_id' : 'topic_id')];
		}
		$this->db->sql_freeresult($result);

		if (!$total_results && $is_mysql)
		{
			// Get the number of results as calculated by MySQL
			$sql_count = 'SELECT FOUND_ROWS() as total_results';
			$result = $this->db->sql_query($sql_count);
			$total_results = (int) $this->db->sql_fetchfield('total_results');
			$this->db->sql_freeresult($result);

			if (!$total_results)
			{
				return false;
			}
		}

		if ($start >= $total_results)
		{
			$start = floor(($total_results - 1) / $per_page) * $per_page;

			$result = $this->db->sql_query_limit($sql, $this->config['search_block_size'], $start);

			while ($row = $this->db->sql_fetchrow($result))
			{
				$id_ary[] = (int) $row[(($type == 'posts') ? 'post_id' : 'topic_id')];
			}
			$this->db->sql_freeresult($result);

		}

		// store the ids, from start on then delete anything that isn't on the current page because we only need ids for one page
		$this->save_ids($search_key, $this->search_query, $author_ary, $total_results, $id_ary, $start, $sort_dir);
		$id_ary = array_slice($id_ary, 0, (int) $per_page);

		return $total_results;
	}

	/**
	* Performs a search on an author's posts without caring about message contents. Depends on display specific params
	*
	* @param	string		$type				contains either posts or topics depending on what should be searched for
	* @param	boolean		$firstpost_only		if true, only topic starting posts will be considered
	* @param	array		$sort_by_sql		contains SQL code for the ORDER BY part of a query
	* @param	string		$sort_key			is the key of $sort_by_sql for the selected sorting
	* @param	string		$sort_dir			is either a or d representing ASC and DESC
	* @param	string		$sort_days			specifies the maximum amount of days a post may be old
	* @param	array		$ex_fid_ary			specifies an array of forum ids which should not be searched
	* @param	string		$post_visibility	specifies which types of posts the user can view in which forums
	* @param	int			$topic_id			is set to 0 or a topic id, if it is not 0 then only posts in this topic should be searched
	* @param	array		$author_ary			an array of author ids
	* @param	string		$author_name		specifies the author match, when ANONYMOUS is also a search-match
	* @param	array		&$id_ary			passed by reference, to be filled with ids for the page specified by $start and $per_page, should be ordered
	* @param	int			$start				indicates the first index of the page
	* @param	int			$per_page			number of ids each page is supposed to contain
	* @return	boolean|int						total number of results
	*/
	public function author_search($type, $firstpost_only, $sort_by_sql, $sort_key, $sort_dir, $sort_days, $ex_fid_ary, $post_visibility, $topic_id, $author_ary, $author_name, &$id_ary, &$start, $per_page)
	{
		// No author? No posts
		if (!count($author_ary))
		{
			return 0;
		}

		// generate a search_key from all the options to identify the results
		$search_key_array = array(
			'',
			$type,
			($firstpost_only) ? 'firstpost' : '',
			'',
			'',
			$sort_days,
			$sort_key,
			$topic_id,
			implode(',', $ex_fid_ary),
			$post_visibility,
			implode(',', $author_ary),
			$author_name,
		);

		/**
		* Allow changing the search_key for cached results
		*
		* @event core.search_native_by_author_modify_search_key
		* @var	array	search_key_array	Array with search parameters to generate the search_key
		* @var	string	type				Searching type ('posts', 'topics')
		* @var	boolean	firstpost_only		Flag indicating if only topic starting posts are considered
		* @var	int		sort_days			Time, in days, of the oldest possible post to list
		* @var	string	sort_key			The sort type used from the possible sort types
		* @var	int		topic_id			Limit the search to this topic_id only
		* @var	array	ex_fid_ary			Which forums not to search on
		* @var	string	post_visibility		Post visibility data
		* @var	array	author_ary			Array of user_id containing the users to filter the results to
		* @var	string	author_name			The username to search on
		* @since 3.1.7-RC1
		*/
		$vars = array(
			'search_key_array',
			'type',
			'firstpost_only',
			'sort_days',
			'sort_key',
			'topic_id',
			'ex_fid_ary',
			'post_visibility',
			'author_ary',
			'author_name',
		);
		extract($this->phpbb_dispatcher->trigger_event('core.search_native_by_author_modify_search_key', compact($vars)));

		$search_key = md5(implode('#', $search_key_array));

		// try reading the results from cache
		$total_results = 0;
		if ($this->obtain_ids($search_key, $total_results, $id_ary, $start, $per_page, $sort_dir) == SEARCH_RESULT_IN_CACHE)
		{
			return $total_results;
		}

		$id_ary = array();

		// Create some display specific sql strings
		if ($author_name)
		{
			// first one matches post of registered users, second one guests and deleted users
			$sql_author = '(' . $this->db->sql_in_set('p.poster_id', array_diff($author_ary, array(ANONYMOUS)), false, true) . ' OR p.post_username ' . $author_name . ')';
		}
		else
		{
			$sql_author = $this->db->sql_in_set('p.poster_id', $author_ary);
		}
		$sql_fora		= (count($ex_fid_ary)) ? ' AND ' . $this->db->sql_in_set('p.forum_id', $ex_fid_ary, true) : '';
		$sql_time		= ($sort_days) ? ' AND p.post_time >= ' . (time() - ($sort_days * 86400)) : '';
		$sql_topic_id	= ($topic_id) ? ' AND p.topic_id = ' . (int) $topic_id : '';
		$sql_firstpost = ($firstpost_only) ? ' AND p.post_id = t.topic_first_post_id' : '';
		$post_visibility = ($post_visibility) ? ' AND ' . $post_visibility : '';

		// Build sql strings for sorting
		$sql_sort = $sort_by_sql[$sort_key] . (($sort_dir == 'a') ? ' ASC' : ' DESC');
		$sql_sort_table = $sql_sort_join = '';
		switch ($sql_sort[0])
		{
			case 'u':
				$sql_sort_table	= USERS_TABLE . ' u, ';
				$sql_sort_join	= ' AND u.user_id = p.poster_id ';
			break;

			case 't':
				$sql_sort_table	= ($type == 'posts' && !$firstpost_only) ? TOPICS_TABLE . ' t, ' : '';
				$sql_sort_join	= ($type == 'posts' && !$firstpost_only) ? ' AND t.topic_id = p.topic_id ' : '';
			break;

			case 'f':
				$sql_sort_table	= FORUMS_TABLE . ' f, ';
				$sql_sort_join	= ' AND f.forum_id = p.forum_id ';
			break;
		}

		$select = ($type == 'posts') ? 'p.post_id' : 't.topic_id';
		$is_mysql = false;

		/**
		* Allow changing the query used to search for posts by author in fulltext_native
		*
		* @event core.search_native_author_count_query_before
		* @var	int		total_results		The previous result count for the format of the query.
		*									Set to 0 to force a re-count
		* @var	string	type				The type of search being made
		* @var	string	select				SQL SELECT clause for what to get
		* @var	string	sql_sort_table		CROSS JOIN'ed table to allow doing the sort chosen
		* @var	string	sql_sort_join		Condition to define how to join the CROSS JOIN'ed table specifyed in sql_sort_table
		* @var	array	sql_author			SQL WHERE condition for the post author ids
		* @var	int		topic_id			Limit the search to this topic_id only
		* @var	string	sort_by_sql			The possible predefined sort types
		* @var	string	sort_key			The sort type used from the possible sort types
		* @var	string	sort_dir			"a" for ASC or "d" dor DESC for the sort order used
		* @var	string	sql_sort			The result SQL when processing sort_by_sql + sort_key + sort_dir
		* @var	string	sort_days			Time, in days, that the oldest post showing can have
		* @var	string	sql_time			The SQL to search on the time specifyed by sort_days
		* @var	bool	firstpost_only		Wether or not to search only on the first post of the topics
		* @var	string	sql_firstpost		The SQL used in the WHERE claused to filter by firstpost.
		* @var	array	ex_fid_ary			Forum ids that must not be searched on
		* @var	array	sql_fora			SQL query for ex_fid_ary
		* @var	int		start				How many posts to skip in the search results (used for pagination)
		* @since 3.1.5-RC1
		*/
		$vars = array(
			'total_results',
			'type',
			'select',
			'sql_sort_table',
			'sql_sort_join',
			'sql_author',
			'topic_id',
			'sort_by_sql',
			'sort_key',
			'sort_dir',
			'sql_sort',
			'sort_days',
			'sql_time',
			'firstpost_only',
			'sql_firstpost',
			'ex_fid_ary',
			'sql_fora',
			'start',
		);
		extract($this->phpbb_dispatcher->trigger_event('core.search_native_author_count_query_before', compact($vars)));

		// If the cache was completely empty count the results
		if (!$total_results)
		{
			switch ($this->db->get_sql_layer())
			{
				case 'mysqli':
//					$select = 'SQL_CALC_FOUND_ROWS ' . $select;
					$is_mysql = true;
				break;

				default:
					if ($type == 'posts')
					{
						$sql = 'SELECT COUNT(p.post_id) as total_results
							FROM ' . POSTS_TABLE . ' p' . (($firstpost_only) ? ', ' . TOPICS_TABLE . ' t ' : ' ') . "
							WHERE $sql_author
								$sql_topic_id
								$sql_firstpost
								$post_visibility
								$sql_fora
								$sql_time";
					}
					else
					{
						if ($this->db->get_sql_layer() == 'sqlite3')
						{
							$sql = 'SELECT COUNT(topic_id) as total_results
								FROM (SELECT DISTINCT t.topic_id';
						}
						else
						{
							$sql = 'SELECT COUNT(DISTINCT t.topic_id) as total_results';
						}

						$sql .= ' FROM ' . TOPICS_TABLE . ' t, ' . POSTS_TABLE . " p
							WHERE $sql_author
								$sql_topic_id
								$sql_firstpost
								$post_visibility
								$sql_fora
								AND t.topic_id = p.topic_id
								$sql_time" . ($this->db->get_sql_layer() == 'sqlite3' ? ')' : '');
					}
					$result = $this->db->sql_query($sql);

					$total_results = (int) $this->db->sql_fetchfield('total_results');
					$this->db->sql_freeresult($result);

					if (!$total_results)
					{
						return false;
					}
				break;
			}
		}

		// Build the query for really selecting the post_ids
		if ($type == 'posts')
		{
			$sql = "SELECT $select
				FROM " . $sql_sort_table . POSTS_TABLE . ' p' . (($firstpost_only) ? ', ' . TOPICS_TABLE . ' t' : '') . "
				WHERE $sql_author
					$sql_topic_id
					$sql_firstpost
					$post_visibility
					$sql_fora
					$sql_sort_join
					$sql_time
				ORDER BY $sql_sort";
			$field = 'post_id';
		}
		else
		{
			$sql = "SELECT $select
				FROM " . $sql_sort_table . TOPICS_TABLE . ' t, ' . POSTS_TABLE . " p
				WHERE $sql_author
					$sql_topic_id
					$sql_firstpost
					$post_visibility
					$sql_fora
					AND t.topic_id = p.topic_id
					$sql_sort_join
					$sql_time
				GROUP BY t.topic_id, " . $sort_by_sql[$sort_key] . '
				ORDER BY ' . $sql_sort;
			$field = 'topic_id';
		}

		// Only read one block of posts from the db and then cache it
		$result = $this->db->sql_query_limit($sql, $this->config['search_block_size'], $start);

		while ($row = $this->db->sql_fetchrow($result))
		{
			$id_ary[] = (int) $row[$field];
		}
		$this->db->sql_freeresult($result);

		if (!$total_results && $is_mysql)
		{
			// Count rows for the executed queries. Replace $select within $sql with SQL_CALC_FOUND_ROWS, and run it.
			$sql_calc = str_replace('SELECT ' . $select, 'SELECT SQL_CALC_FOUND_ROWS ' . $select, $sql);

			$result = $this->db->sql_query($sql_calc);
			$this->db->sql_freeresult($result);

			$sql_count = 'SELECT FOUND_ROWS() as total_results';
			$result = $this->db->sql_query($sql_count);
			$total_results = (int) $this->db->sql_fetchfield('total_results');
			$this->db->sql_freeresult($result);

			if (!$total_results)
			{
				return false;
			}
		}

		if ($start >= $total_results)
		{
			$start = floor(($total_results - 1) / $per_page) * $per_page;

			$result = $this->db->sql_query_limit($sql, $this->config['search_block_size'], $start);

			while ($row = $this->db->sql_fetchrow($result))
			{
				$id_ary[] = (int) $row[$field];
			}
			$this->db->sql_freeresult($result);
		}

		if (count($id_ary))
		{
			$this->save_ids($search_key, '', $author_ary, $total_results, $id_ary, $start, $sort_dir);
			$id_ary = array_slice($id_ary, 0, $per_page);

			return $total_results;
		}
		return false;
	}

	/**
	* Split a text into words of a given length
	*
	* The text is converted to UTF-8, cleaned up, and split. Then, words that
	* conform to the defined length range are returned in an array.
	*
	* NOTE: duplicates are NOT removed from the return array
	*
	* @param	string	$text	Text to split, encoded in UTF-8
	* @return	array			Array of UTF-8 words
	*/
	public function split_message($text)
	{
		$match = $words = array();

		/**
		* Taken from the original code
		*/
		// Do not index code
		$match[] = '#\[code(?:=.*?)?(\:?[0-9a-z]{5,})\].*?\[\/code(\:?[0-9a-z]{5,})\]#is';
		// BBcode
		$match[] = '#\[\/?[a-z0-9\*\+\-]+(?:=.*?)?(?::[a-z])?(\:?[0-9a-z]{5,})\]#';

		$min = $this->word_length['min'];

		$isset_min = $min - 1;

		/**
		* Clean up the string, remove HTML tags, remove BBCodes
		*/
		$word = strtok($this->cleanup(preg_replace($match, ' ', strip_tags($text)), -1), ' ');

		while (strlen($word))
		{
			if (strlen($word) > 255 || strlen($word) <= $isset_min)
			{
				/**
				* Words longer than 255 bytes are ignored. This will have to be
				* changed whenever we change the length of search_wordlist.word_text
				*
				* Words shorter than $isset_min bytes are ignored, too
				*/
				$word = strtok(' ');
				continue;
			}

			$len = utf8_strlen($word);

			/**
			* Test whether the word is too short to be indexed.
			*
			* Note that this limit does NOT apply to CJK and Hangul
			*/
			if ($len < $min)
			{
				/**
				* Note: this could be optimized. If the codepoint is lower than Hangul's range
				* we know that it will also be lower than CJK ranges
				*/
				if ((strncmp($word, self::UTF8_HANGUL_FIRST, 3) < 0 || strncmp($word, self::UTF8_HANGUL_LAST, 3) > 0)
					&& (strncmp($word, self::UTF8_CJK_FIRST, 3) < 0 || strncmp($word, self::UTF8_CJK_LAST, 3) > 0)
					&& (strncmp($word, self::UTF8_CJK_B_FIRST, 4) < 0 || strncmp($word, self::UTF8_CJK_B_LAST, 4) > 0))
				{
					$word = strtok(' ');
					continue;
				}
			}

			$words[] = $word;
			$word = strtok(' ');
		}

		return $words;
	}

	/**
	* Updates wordlist and wordmatch tables when a message is posted or changed
	*
	* @param	string	$mode		Contains the post mode: edit, post, reply, quote
	* @param	int		$post_id	The id of the post which is modified/created
	* @param	string	&$message	New or updated post content
	* @param	string	&$subject	New or updated post subject
	* @param	int		$poster_id	Post author's user id
	* @param	int		$forum_id	The id of the forum in which the post is located
	*/
	public function index($mode, $post_id, &$message, &$subject, $poster_id, $forum_id)
	{
		if (!$this->config['fulltext_native_load_upd'])
		{
			/**
			* The search indexer is disabled, return
			*/
			return;
		}

		// Split old and new post/subject to obtain array of 'words'
		$split_text = $this->split_message($message);
		$split_title = $this->split_message($subject);

		$cur_words = array('post' => array(), 'title' => array());

		$words = array();
		if ($mode == 'edit')
		{
			$words['add']['post'] = array();
			$words['add']['title'] = array();
			$words['del']['post'] = array();
			$words['del']['title'] = array();

			$sql = 'SELECT w.word_id, w.word_text, m.title_match
				FROM ' . SEARCH_WORDLIST_TABLE . ' w, ' . SEARCH_WORDMATCH_TABLE . " m
				WHERE m.post_id = $post_id
					AND w.word_id = m.word_id";
			$result = $this->db->sql_query($sql);

			while ($row = $this->db->sql_fetchrow($result))
			{
				$which = ($row['title_match']) ? 'title' : 'post';
				$cur_words[$which][$row['word_text']] = $row['word_id'];
			}
			$this->db->sql_freeresult($result);

			$words['add']['post'] = array_diff($split_text, array_keys($cur_words['post']));
			$words['add']['title'] = array_diff($split_title, array_keys($cur_words['title']));
			$words['del']['post'] = array_diff(array_keys($cur_words['post']), $split_text);
			$words['del']['title'] = array_diff(array_keys($cur_words['title']), $split_title);
		}
		else
		{
			$words['add']['post'] = $split_text;
			$words['add']['title'] = $split_title;
			$words['del']['post'] = array();
			$words['del']['title'] = array();
		}

		/**
		* Event to modify method arguments and words before the native search index is updated
		*
		* @event core.search_native_index_before
		* @var string	mode				Contains the post mode: edit, post, reply, quote
		* @var int		post_id				The id of the post which is modified/created
		* @var string	message				New or updated post content
		* @var string	subject				New or updated post subject
		* @var int		poster_id			Post author's user id
		* @var int		forum_id			The id of the forum in which the post is located
		* @var array	words				Grouped lists of words added to or remove from the index
		* @var array	split_text			Array of words from the message
		* @var array	split_title			Array of words from the title
		* @var array	cur_words			Array of words currently in the index for comparing to new words
		* 									when mode is edit. Empty for other modes.
		* @since 3.2.3-RC1
		*/
		$vars = array(
			'mode',
			'post_id',
			'message',
			'subject',
			'poster_id',
			'forum_id',
			'words',
			'split_text',
			'split_title',
			'cur_words',
		);
		extract($this->phpbb_dispatcher->trigger_event('core.search_native_index_before', compact($vars)));

		unset($split_text);
		unset($split_title);

		// Get unique words from the above arrays
		$unique_add_words = array_unique(array_merge($words['add']['post'], $words['add']['title']));

		// We now have unique arrays of all words to be added and removed and
		// individual arrays of added and removed words for text and title. What
		// we need to do now is add the new words (if they don't already exist)
		// and then add (or remove) matches between the words and this post
		if (count($unique_add_words))
		{
			$sql = 'SELECT word_id, word_text
				FROM ' . SEARCH_WORDLIST_TABLE . '
				WHERE ' . $this->db->sql_in_set('word_text', $unique_add_words);
			$result = $this->db->sql_query($sql);

			$word_ids = array();
			while ($row = $this->db->sql_fetchrow($result))
			{
				$word_ids[$row['word_text']] = $row['word_id'];
			}
			$this->db->sql_freeresult($result);
			$new_words = array_diff($unique_add_words, array_keys($word_ids));

			$this->db->sql_transaction('begin');
			if (count($new_words))
			{
				$sql_ary = array();

				foreach ($new_words as $word)
				{
					$sql_ary[] = array('word_text' => (string) $word, 'word_count' => 0);
				}
				$this->db->sql_return_on_error(true);
				$this->db->sql_multi_insert(SEARCH_WORDLIST_TABLE, $sql_ary);
				$this->db->sql_return_on_error(false);
			}
			unset($new_words, $sql_ary);
		}
		else
		{
			$this->db->sql_transaction('begin');
		}

		// now update the search match table, remove links to removed words and add links to new words
		foreach ($words['del'] as $word_in => $word_ary)
		{
			$title_match = ($word_in == 'title') ? 1 : 0;

			if (count($word_ary))
			{
				$sql_in = array();
				foreach ($word_ary as $word)
				{
					$sql_in[] = $cur_words[$word_in][$word];
				}

				$sql = 'DELETE FROM ' . SEARCH_WORDMATCH_TABLE . '
					WHERE ' . $this->db->sql_in_set('word_id', $sql_in) . '
						AND post_id = ' . intval($post_id) . "
						AND title_match = $title_match";
				$this->db->sql_query($sql);

				$sql = 'UPDATE ' . SEARCH_WORDLIST_TABLE . '
					SET word_count = word_count - 1
					WHERE ' . $this->db->sql_in_set('word_id', $sql_in) . '
						AND word_count > 0';
				$this->db->sql_query($sql);

				unset($sql_in);
			}
		}

		$this->db->sql_return_on_error(true);
		foreach ($words['add'] as $word_in => $word_ary)
		{
			$title_match = ($word_in == 'title') ? 1 : 0;

			if (count($word_ary))
			{
				$sql = 'INSERT INTO ' . SEARCH_WORDMATCH_TABLE . ' (post_id, word_id, title_match)
					SELECT ' . (int) $post_id . ', word_id, ' . (int) $title_match . '
					FROM ' . SEARCH_WORDLIST_TABLE . '
					WHERE ' . $this->db->sql_in_set('word_text', $word_ary);
				$this->db->sql_query($sql);

				$sql = 'UPDATE ' . SEARCH_WORDLIST_TABLE . '
					SET word_count = word_count + 1
					WHERE ' . $this->db->sql_in_set('word_text', $word_ary);
				$this->db->sql_query($sql);
			}
		}
		$this->db->sql_return_on_error(false);

		$this->db->sql_transaction('commit');

		// destroy cached search results containing any of the words removed or added
		$this->destroy_cache(array_unique(array_merge($words['add']['post'], $words['add']['title'], $words['del']['post'], $words['del']['title'])), array($poster_id));

		unset($unique_add_words);
		unset($words);
		unset($cur_words);
	}

	/**
	* Removes entries from the wordmatch table for the specified post_ids
	*/
	public function index_remove($post_ids, $author_ids, $forum_ids)
	{
		if (count($post_ids))
		{
			$sql = 'SELECT w.word_id, w.word_text, m.title_match
				FROM ' . SEARCH_WORDMATCH_TABLE . ' m, ' . SEARCH_WORDLIST_TABLE . ' w
				WHERE ' . $this->db->sql_in_set('m.post_id', $post_ids) . '
					AND w.word_id = m.word_id';
			$result = $this->db->sql_query($sql);

			$message_word_ids = $title_word_ids = $word_texts = array();
			while ($row = $this->db->sql_fetchrow($result))
			{
				if ($row['title_match'])
				{
					$title_word_ids[] = $row['word_id'];
				}
				else
				{
					$message_word_ids[] = $row['word_id'];
				}
				$word_texts[] = $row['word_text'];
			}
			$this->db->sql_freeresult($result);

			if (count($title_word_ids))
			{
				$sql = 'UPDATE ' . SEARCH_WORDLIST_TABLE . '
					SET word_count = word_count - 1
					WHERE ' . $this->db->sql_in_set('word_id', $title_word_ids) . '
						AND word_count > 0';
				$this->db->sql_query($sql);
			}

			if (count($message_word_ids))
			{
				$sql = 'UPDATE ' . SEARCH_WORDLIST_TABLE . '
					SET word_count = word_count - 1
					WHERE ' . $this->db->sql_in_set('word_id', $message_word_ids) . '
						AND word_count > 0';
				$this->db->sql_query($sql);
			}

			unset($title_word_ids);
			unset($message_word_ids);

			$sql = 'DELETE FROM ' . SEARCH_WORDMATCH_TABLE . '
				WHERE ' . $this->db->sql_in_set('post_id', $post_ids);
			$this->db->sql_query($sql);
		}

		$this->destroy_cache(array_unique($word_texts), array_unique($author_ids));
	}

	/**
	* Tidy up indexes: Tag 'common words' and remove
	* words no longer referenced in the match table
	*/
	public function tidy()
	{
		// Is the fulltext indexer disabled? If yes then we need not
		// carry on ... it's okay ... I know when I'm not wanted boo hoo
		if (!$this->config['fulltext_native_load_upd'])
		{
			$this->config->set('search_last_gc', time(), false);
			return;
		}

		$destroy_cache_words = array();

		// Remove common words
		if ($this->config['num_posts'] >= 100 && $this->config['fulltext_native_common_thres'])
		{
			$common_threshold = ((double) $this->config['fulltext_native_common_thres']) / 100.0;
			// First, get the IDs of common words
			$sql = 'SELECT word_id, word_text
				FROM ' . SEARCH_WORDLIST_TABLE . '
				WHERE word_count > ' . floor($this->config['num_posts'] * $common_threshold) . '
					OR word_common = 1';
			$result = $this->db->sql_query($sql);

			$sql_in = array();
			while ($row = $this->db->sql_fetchrow($result))
			{
				$sql_in[] = $row['word_id'];
				$destroy_cache_words[] = $row['word_text'];
			}
			$this->db->sql_freeresult($result);

			if (count($sql_in))
			{
				// Flag the words
				$sql = 'UPDATE ' . SEARCH_WORDLIST_TABLE . '
					SET word_common = 1
					WHERE ' . $this->db->sql_in_set('word_id', $sql_in);
				$this->db->sql_query($sql);

				// by setting search_last_gc to the new time here we make sure that if a user reloads because the
				// following query takes too long, he won't run into it again
				$this->config->set('search_last_gc', time(), false);

				// Delete the matches
				$sql = 'DELETE FROM ' . SEARCH_WORDMATCH_TABLE . '
					WHERE ' . $this->db->sql_in_set('word_id', $sql_in);
				$this->db->sql_query($sql);
			}
			unset($sql_in);
		}

		if (count($destroy_cache_words))
		{
			// destroy cached search results containing any of the words that are now common or were removed
			$this->destroy_cache(array_unique($destroy_cache_words));
		}

		$this->config->set('search_last_gc', time(), false);
	}

	/**
	* Deletes all words from the index
	*/
	public function delete_index($acp_module, $u_action)
	{
		$sql_queries = [];

		switch ($this->db->get_sql_layer())
		{
			case 'sqlite3':
				$sql_queries[] = 'DELETE FROM ' . SEARCH_WORDLIST_TABLE;
				$sql_queries[] = 'DELETE FROM ' . SEARCH_WORDMATCH_TABLE;
				$sql_queries[] = 'DELETE FROM ' . SEARCH_RESULTS_TABLE;
			break;

			default:
				$sql_queries[] = 'TRUNCATE TABLE ' . SEARCH_WORDLIST_TABLE;
				$sql_queries[] = 'TRUNCATE TABLE ' . SEARCH_WORDMATCH_TABLE;
				$sql_queries[] = 'TRUNCATE TABLE ' . SEARCH_RESULTS_TABLE;
			break;
		}

		$stats = $this->stats;

		/**
		* Event to modify SQL queries before the native search index is deleted
		*
		* @event core.search_native_delete_index_before
		* @var array	sql_queries			Array with queries for deleting the search index
		* @var array	stats				Array with statistics of the current index (read only)
		* @since 3.2.3-RC1
		*/
		$vars = array(
			'sql_queries',
			'stats',
		);
		extract($this->phpbb_dispatcher->trigger_event('core.search_native_delete_index_before', compact($vars)));

		foreach ($sql_queries as $sql_query)
		{
			$this->db->sql_query($sql_query);
		}
	}

	/**
	* Returns true if both FULLTEXT indexes exist
	*/
	public function index_created()
	{
		if (!count($this->stats))
		{
			$this->get_stats();
		}

		return ($this->stats['total_words'] && $this->stats['total_matches']) ? true : false;
	}

	/**
	* Returns an associative array containing information about the indexes
	*/
	public function index_stats()
	{
		if (!count($this->stats))
		{
			$this->get_stats();
		}

		return array(
			$this->user->lang['TOTAL_WORDS']		=> $this->stats['total_words'],
			$this->user->lang['TOTAL_MATCHES']	=> $this->stats['total_matches']);
	}

	protected function get_stats()
	{
		$this->stats['total_words']		= $this->db->get_estimated_row_count(SEARCH_WORDLIST_TABLE);
		$this->stats['total_matches']	= $this->db->get_estimated_row_count(SEARCH_WORDMATCH_TABLE);
	}

	/**
	* Clean up a text to remove non-alphanumeric characters
	*
	* This method receives a UTF-8 string, normalizes and validates it, replaces all
	* non-alphanumeric characters with strings then returns the result.
	*
	* Any number of "allowed chars" can be passed as a UTF-8 string in NFC.
	*
	* @param	string	$text			Text to split, in UTF-8 (not normalized or sanitized)
	* @param	string	$allowed_chars	String of special chars to allow
	* @param	string	$encoding		Text encoding
	* @return	string					Cleaned up text, only alphanumeric chars are left
	*/
	protected function cleanup($text, $allowed_chars = null, $encoding = 'utf-8')
	{
		static $conv = array(), $conv_loaded = array();
		$allow = array();

		// Convert the text to UTF-8
		$encoding = strtolower($encoding);
		if ($encoding != 'utf-8')
		{
			$text = utf8_recode($text, $encoding);
		}

		$utf_len_mask = array(
			"\xC0"	=>	2,
			"\xD0"	=>	2,
			"\xE0"	=>	3,
			"\xF0"	=>	4
		);

		/**
		* Replace HTML entities and NCRs
		*/
		$text = htmlspecialchars_decode(utf8_decode_ncr($text), ENT_QUOTES);

		/**
		* Normalize to NFC
		*/
		$text = \Normalizer::normalize($text);

		/**
		* The first thing we do is:
		*
		* - convert ASCII-7 letters to lowercase
		* - remove the ASCII-7 non-alpha characters
		* - remove the bytes that should not appear in a valid UTF-8 string: 0xC0,
		*   0xC1 and 0xF5-0xFF
		*
		* @todo in theory, the third one is already taken care of during normalization and those chars should have been replaced by Unicode replacement chars
		*/
		$sb_match	= "ISTCPAMELRDOJBNHFGVWUQKYXZ\r\n\t!\"#$%&'()*+,-./:;<=>?@[\\]^_`{|}~\x00\x01\x02\x03\x04\x05\x06\x07\x08\x0B\x0C\x0E\x0F\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1A\x1B\x1C\x1D\x1E\x1F\xC0\xC1\xF5\xF6\xF7\xF8\xF9\xFA\xFB\xFC\xFD\xFE\xFF";
		$sb_replace	= 'istcpamelrdojbnhfgvwuqkyxz                                                                              ';

		/**
		* This is the list of legal ASCII chars, it is automatically extended
		* with ASCII chars from $allowed_chars
		*/
		$legal_ascii = ' eaisntroludcpmghbfvq10xy2j9kw354867z';

		/**
		* Prepare an array containing the extra chars to allow
		*/
		if (isset($allowed_chars[0]))
		{
			$pos = 0;
			$len = strlen($allowed_chars);
			do
			{
				$c = $allowed_chars[$pos];

				if ($c < "\x80")
				{
					/**
					* ASCII char
					*/
					$sb_pos = strpos($sb_match, $c);
					if (is_int($sb_pos))
					{
						/**
						* Remove the char from $sb_match and its corresponding
						* replacement in $sb_replace
						*/
						$sb_match = substr($sb_match, 0, $sb_pos) . substr($sb_match, $sb_pos + 1);
						$sb_replace = substr($sb_replace, 0, $sb_pos) . substr($sb_replace, $sb_pos + 1);
						$legal_ascii .= $c;
					}

					++$pos;
				}
				else
				{
					/**
					* UTF-8 char
					*/
					$utf_len = $utf_len_mask[$c & "\xF0"];
					$allow[substr($allowed_chars, $pos, $utf_len)] = 1;
					$pos += $utf_len;
				}
			}
			while ($pos < $len);
		}

		$text = strtr($text, $sb_match, $sb_replace);
		$ret = '';

		$pos = 0;
		$len = strlen($text);

		do
		{
			/**
			* Do all consecutive ASCII chars at once
			*/
			if ($spn = strspn($text, $legal_ascii, $pos))
			{
				$ret .= substr($text, $pos, $spn);
				$pos += $spn;
			}

			if ($pos >= $len)
			{
				return $ret;
			}

			/**
			* Capture the UTF char
			*/
			$utf_len = $utf_len_mask[$text[$pos] & "\xF0"];
			$utf_char = substr($text, $pos, $utf_len);
			$pos += $utf_len;

			if (($utf_char >= self::UTF8_HANGUL_FIRST && $utf_char <= self::UTF8_HANGUL_LAST)
				|| ($utf_char >= self::UTF8_CJK_FIRST && $utf_char <= self::UTF8_CJK_LAST)
				|| ($utf_char >= self::UTF8_CJK_B_FIRST && $utf_char <= self::UTF8_CJK_B_LAST))
			{
				/**
				* All characters within these ranges are valid
				*
				* We separate them with a space in order to index each character
				* individually
				*/
				$ret .= ' ' . $utf_char . ' ';
				continue;
			}

			if (isset($allow[$utf_char]))
			{
				/**
				* The char is explicitly allowed
				*/
				$ret .= $utf_char;
				continue;
			}

			if (isset($conv[$utf_char]))
			{
				/**
				* The char is mapped to something, maybe to itself actually
				*/
				$ret .= $conv[$utf_char];
				continue;
			}

			/**
			* The char isn't mapped, but did we load its conversion table?
			*
			* The search indexer table is split into blocks. The block number of
			* each char is equal to its codepoint right-shifted for 11 bits. It
			* means that out of the 11, 16 or 21 meaningful bits of a 2-, 3- or
			* 4- byte sequence we only keep the leftmost 0, 5 or 10 bits. Thus,
			* all UTF chars encoded in 2 bytes are in the same first block.
			*/
			if (isset($utf_char[2]))
			{
				if (isset($utf_char[3]))
				{
					/**
					* 1111 0nnn 10nn nnnn 10nx xxxx 10xx xxxx
					* 0000 0111 0011 1111 0010 0000
					*/
					$idx = ((ord($utf_char[0]) & 0x07) << 7) | ((ord($utf_char[1]) & 0x3F) << 1) | ((ord($utf_char[2]) & 0x20) >> 5);
				}
				else
				{
					/**
					* 1110 nnnn 10nx xxxx 10xx xxxx
					* 0000 0111 0010 0000
					*/
					$idx = ((ord($utf_char[0]) & 0x07) << 1) | ((ord($utf_char[1]) & 0x20) >> 5);
				}
			}
			else
			{
				/**
				* 110x xxxx 10xx xxxx
				* 0000 0000 0000 0000
				*/
				$idx = 0;
			}

			/**
			* Check if the required conv table has been loaded already
			*/
			if (!isset($conv_loaded[$idx]))
			{
				$conv_loaded[$idx] = 1;
				$file = $this->phpbb_root_path . 'includes/utf/data/search_indexer_' . $idx . '.' . $this->php_ext;

				if (file_exists($file))
				{
					$conv += include($file);
				}
			}

			if (isset($conv[$utf_char]))
			{
				$ret .= $conv[$utf_char];
			}
			else
			{
				/**
				* We add an entry to the conversion table so that we
				* don't have to convert to codepoint and perform the checks
				* that are above this block
				*/
				$conv[$utf_char] = ' ';
				$ret .= ' ';
			}
		}
		while (1);

		return $ret;
	}

	/**
	* Returns a list of options for the ACP to display
	*/
	public function acp()
	{
		/**
		* if we need any options, copied from fulltext_native for now, will have to be adjusted or removed
		*/

		$tpl = '
		<dl>
			<dt><label for="fulltext_native_load_upd">' . $this->user->lang['YES_SEARCH_UPDATE'] . $this->user->lang['COLON'] . '</label><br /><span>' . $this->user->lang['YES_SEARCH_UPDATE_EXPLAIN'] . '</span></dt>
			<dd><label><input type="radio" id="fulltext_native_load_upd" name="config[fulltext_native_load_upd]" value="1"' . (($this->config['fulltext_native_load_upd']) ? ' checked="checked"' : '') . ' class="radio" /> ' . $this->user->lang['YES'] . '</label><label><input type="radio" name="config[fulltext_native_load_upd]" value="0"' . ((!$this->config['fulltext_native_load_upd']) ? ' checked="checked"' : '') . ' class="radio" /> ' . $this->user->lang['NO'] . '</label></dd>
		</dl>
		<dl>
			<dt><label for="fulltext_native_min_chars">' . $this->user->lang['MIN_SEARCH_CHARS'] . $this->user->lang['COLON'] . '</label><br /><span>' . $this->user->lang['MIN_SEARCH_CHARS_EXPLAIN'] . '</span></dt>
			<dd><input id="fulltext_native_min_chars" type="number" min="0" max="255" name="config[fulltext_native_min_chars]" value="' . (int) $this->config['fulltext_native_min_chars'] . '" /></dd>
		</dl>
		<dl>
			<dt><label for="fulltext_native_max_chars">' . $this->user->lang['MAX_SEARCH_CHARS'] . $this->user->lang['COLON'] . '</label><br /><span>' . $this->user->lang['MAX_SEARCH_CHARS_EXPLAIN'] . '</span></dt>
			<dd><input id="fulltext_native_max_chars" type="number" min="0" max="255" name="config[fulltext_native_max_chars]" value="' . (int) $this->config['fulltext_native_max_chars'] . '" /></dd>
		</dl>
		<dl>
			<dt><label for="fulltext_native_common_thres">' . $this->user->lang['COMMON_WORD_THRESHOLD'] . $this->user->lang['COLON'] . '</label><br /><span>' . $this->user->lang['COMMON_WORD_THRESHOLD_EXPLAIN'] . '</span></dt>
			<dd><input id="fulltext_native_common_thres" type="text" name="config[fulltext_native_common_thres]" value="' . (double) $this->config['fulltext_native_common_thres'] . '" /> %</dd>
		</dl>
		';

		// These are fields required in the config table
		return array(
			'tpl'		=> $tpl,
			'config'	=> array('fulltext_native_load_upd' => 'bool', 'fulltext_native_min_chars' => 'integer:0:255', 'fulltext_native_max_chars' => 'integer:0:255', 'fulltext_native_common_thres' => 'double:0:100')
		);
	}
}