summaryrefslogtreecommitdiffstats
path: root/src/corelib/tools/qregularexpression.cpp
blob: 503185dab5dc5cebc6ae0245fcca12d3073b49cd (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
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
2230
2231
2232
2233
2234
2235
2236
2237
2238
2239
2240
2241
2242
2243
2244
2245
2246
2247
2248
2249
2250
2251
2252
2253
2254
2255
2256
2257
2258
2259
2260
2261
2262
2263
2264
2265
2266
2267
2268
2269
2270
2271
2272
2273
2274
2275
2276
2277
2278
2279
2280
2281
2282
2283
2284
2285
2286
2287
2288
2289
2290
2291
2292
2293
2294
2295
2296
2297
2298
2299
2300
2301
2302
2303
2304
2305
2306
2307
2308
2309
2310
2311
2312
2313
2314
2315
2316
2317
2318
2319
2320
2321
2322
2323
2324
2325
2326
2327
2328
2329
2330
2331
2332
2333
2334
2335
2336
2337
2338
2339
2340
2341
2342
2343
2344
2345
2346
2347
2348
2349
2350
2351
2352
2353
2354
2355
2356
2357
2358
2359
2360
2361
2362
2363
2364
2365
2366
2367
2368
2369
2370
2371
2372
2373
2374
2375
2376
2377
2378
2379
2380
2381
2382
2383
2384
2385
2386
2387
2388
2389
2390
2391
2392
2393
2394
2395
2396
2397
2398
2399
2400
2401
2402
2403
2404
2405
2406
2407
2408
2409
2410
2411
2412
2413
/****************************************************************************
**
** Copyright (C) 2012 Giuseppe D'Angelo <dangelog@gmail.com>.
** Copyright (C) 2012 Klarälvdalens Datakonsult AB, a KDAB Group company, info@kdab.com, author Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>
** Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies).
** Contact: http://www.qt-project.org/legal
**
** This file is part of the QtCore module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and Digia.  For licensing terms and
** conditions see http://qt.digia.com/licensing.  For further information
** use the contact form at http://qt.digia.com/contact-us.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Digia gives you certain additional
** rights.  These rights are described in the Digia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3.0 as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU General Public License version 3.0 requirements will be
** met: http://www.gnu.org/copyleft/gpl.html.
**
**
** $QT_END_LICENSE$
**
****************************************************************************/

#include "qregularexpression.h"

#include <QtCore/qcoreapplication.h>
#include <QtCore/qmutex.h>
#include <QtCore/qvector.h>
#include <QtCore/qstringlist.h>
#include <QtCore/qdebug.h>
#include <QtCore/qthreadstorage.h>
#include <QtCore/qglobal.h>

#include <pcre.h>

QT_BEGIN_NAMESPACE

/*!
    \class QRegularExpression
    \inmodule QtCore
    \reentrant

    \brief The QRegularExpression class provides pattern matching using regular
    expressions.

    \since 5.0

    \ingroup tools
    \ingroup shared

    \keyword regular expression

    Regular expressions, or \e{regexps}, are a very powerful tool to handle
    strings and texts. This is useful in many contexts, e.g.,

    \table
    \row \li Validation
         \li A regexp can test whether a substring meets some criteria,
         e.g. is an integer or contains no whitespace.
    \row \li Searching
         \li A regexp provides more powerful pattern matching than
         simple substring matching, e.g., match one of the words
         \e{mail}, \e{letter} or \e{correspondence}, but none of the
         words \e{email}, \e{mailman}, \e{mailer}, \e{letterbox}, etc.
    \row \li Search and Replace
         \li A regexp can replace all occurrences of a substring with a
         different substring, e.g., replace all occurrences of \e{&}
         with \e{\&amp;} except where the \e{&} is already followed by
         an \e{amp;}.
    \row \li String Splitting
         \li A regexp can be used to identify where a string should be
         split apart, e.g. splitting tab-delimited strings.
    \endtable

    This document is by no means a complete reference to pattern matching using
    regular expressions, and the following parts will require the reader to
    have some basic knowledge about Perl-like regular expressions and their
    pattern syntax.

    Good references about regular expressions include:

    \list
    \li \e {Mastering Regular Expressions} (Third Edition) by Jeffrey E. F.
    Friedl, ISBN 0-596-52812-4;
    \li the \l{http://pcre.org/pcre.txt} {pcrepattern(3)} man page, describing
    the pattern syntax supported by PCRE (the reference implementation of
    Perl-compatible regular expressions);
    \li the \l{http://perldoc.perl.org/perlre.html} {Perl's regular expression
    documentation} and the \l{http://perldoc.perl.org/perlretut.html} {Perl's
    regular expression tutorial}.
    \endlist

    \tableofcontents

    \section1 Introduction

    QRegularExpression implements Perl-compatible regular expressions. It fully
    supports Unicode. For an overview of the regular expression syntax
    supported by QRegularExpression, please refer to the aforementioned
    pcrepattern(3) man page. A regular expression is made up of two things: a
    \b{pattern string} and a set of \b{pattern options} that change the
    meaning of the pattern string.

    You can set the pattern string by passing a string to the QRegularExpression
    constructor:

    \snippet code/src_corelib_tools_qregularexpression.cpp 0

    This sets the pattern string to \c{a pattern}. You can also use the
    setPattern() function to set a pattern on an existing QRegularExpression
    object:

    \snippet code/src_corelib_tools_qregularexpression.cpp 1

    Note that due to C++ literal strings rules, you must escape all backslashes
    inside the pattern string with another backslash:

    \snippet code/src_corelib_tools_qregularexpression.cpp 2

    The pattern() function returns the pattern that is currently set for a
    QRegularExpression object:

    \snippet code/src_corelib_tools_qregularexpression.cpp 3

    \section1 Pattern options

    The meaning of the pattern string can be modified by setting one or more
    \e{pattern options}. For instance, it is possible to set a pattern to match
    case insensitively by setting the QRegularExpression::CaseInsensitiveOption.

    You can set the options by passing them to the QRegularExpression
    constructor, as in:

    \snippet code/src_corelib_tools_qregularexpression.cpp 4

    Alternatively, you can use the setPatternOptions() function on an existing
    QRegularExpressionObject:

    \snippet code/src_corelib_tools_qregularexpression.cpp 5

    It is possible to get the pattern options currently set on a
    QRegularExpression object by using the patternOptions() function:

    \snippet code/src_corelib_tools_qregularexpression.cpp 6

    Please refer to the QRegularExpression::PatternOption enum documentation for
    more information about each pattern option.

    \section1 Match type and match options

    The last two arguments of the match() and the globalMatch() functions set
    the match type and the match options. The match type is a value of the
    QRegularExpression::MatchType enum; the "traditional" matching algorithm is
    chosen by using the NormalMatch match type (the default). It is also
    possible to enable partial matching of the regular expression against a
    subject string: see the \l{partial matching} section for more details.

    The match options are a set of one or more QRegularExpression::MatchOption
    values. They change the way a specific match of a regular expression
    against a subject string is done. Please refer to the
    QRegularExpression::MatchOption enum documentation for more details.

    \target normal matching
    \section1 Normal matching

    In order to perform a match you can simply invoke the match() function
    passing a string to match against. We refer to this string as the
    \e{subject string}. The result of the match() function is a
    QRegularExpressionMatch object that can be used to inspect the results of
    the match. For instance:

    \snippet code/src_corelib_tools_qregularexpression.cpp 7

    If a match is successful, the (implicit) capturing group number 0 can be
    used to retrieve the substring matched by the entire pattern (see also the
    section about \l{extracting captured substrings}):

    \snippet code/src_corelib_tools_qregularexpression.cpp 8

    It's also possible to start a match at an arbitrary offset inside the
    subject string by passing the offset as an argument of the
    match() function. In the following example \c{"12 abc"}
    is not matched because the match is started at offset 1:

    \snippet code/src_corelib_tools_qregularexpression.cpp 9

    \target extracting captured substrings
    \section2 Extracting captured substrings

    The QRegularExpressionMatch object contains also information about the
    substrings captured by the capturing groups in the pattern string. The
    \l{QRegularExpressionMatch::}{captured()} function will return the string
    captured by the n-th capturing group:

    \snippet code/src_corelib_tools_qregularexpression.cpp 10

    Capturing groups in the pattern are numbered starting from 1, and the
    implicit capturing group 0 is used to capture the substring that matched
    the entire pattern.

    It's also possible to retrieve the starting and the ending offsets (inside
    the subject string) of each captured substring, by using the
    \l{QRegularExpressionMatch::}{capturedStart()} and the
    \l{QRegularExpressionMatch::}{capturedEnd()} functions:

    \snippet code/src_corelib_tools_qregularexpression.cpp 11

    All of these functions have an overload taking a QString as a parameter
    in order to extract \e{named} captured substrings. For instance:

    \snippet code/src_corelib_tools_qregularexpression.cpp 12

    \target global matching
    \section1 Global matching

    \e{Global matching} is useful to find all the occurrences of a given
    regular expression inside a subject string. Suppose that we want to extract
    all the words from a given string, where a word is a substring matching
    the pattern \c{\w+}.

    QRegularExpression::globalMatch returns a QRegularExpressionMatchIterator,
    which is a Java-like forward iterator that can be used to iterate over the
    results. For instance:

    \snippet code/src_corelib_tools_qregularexpression.cpp 13

    Since it's a Java-like iterator, the QRegularExpressionMatchIterator will
    point immediately before the first result. Every result is returned as a
    QRegularExpressionMatch object. The
    \l{QRegularExpressionMatchIterator::}{hasNext()} function will return true
    if there's at least one more result, and
    \l{QRegularExpressionMatchIterator::}{next()} will return the next result
    and advance the iterator. Continuing from the previous example:

    \snippet code/src_corelib_tools_qregularexpression.cpp 14

    You can also use \l{QRegularExpressionMatchIterator::}{peekNext()} to get
    the next result without advancing the iterator.

    It is possible to pass a starting offset and one or more match options to
    the globalMatch() function, exactly like normal matching with match().

    \target partial matching
    \section1 Partial matching

    A \e{partial match} is obtained when the end of the subject string is
    reached, but more characters are needed to successfully complete the match.
    Note that a partial match is usually much more inefficient than a normal
    match because many optimizations of the matching algorithm cannot be
    employed.

    A partial match must be explicitly requested by specifying a match type of
    PartialPreferCompleteMatch or PartialPreferFirstMatch when calling
    QRegularExpression::match or QRegularExpression::globalMatch. If a partial
    match is found, then calling the \l{QRegularExpressionMatch::}{hasMatch()}
    function on the QRegularExpressionMatch object returned by match() will
    return \c{false}, but \l{QRegularExpressionMatch::}{hasPartialMatch()} will return
    \c{true}.

    When a partial match is found, no captured substrings are returned, and the
    (implicit) capturing group 0 corresponding to the whole match captures the
    partially matched substring of the subject string.

    Note that asking for a partial match can still lead to a complete match, if
    one is found; in this case, \l{QRegularExpressionMatch::}{hasMatch()} will
    return \c{true} and \l{QRegularExpressionMatch::}{hasPartialMatch()}
    \c{false}. It never happens that a QRegularExpressionMatch reports both a
    partial and a complete match.

    Partial matching is mainly useful in two scenarios: validating user input
    in real time and incremental/multi-segment matching.

    \target validating user input
    \section2 Validating user input

    Suppose that we would like the user to input a date in a specific
    format, for instance "MMM dd, yyyy". We can check the input validity with
    a pattern like:

    \c{^(Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec) \d\d?, \d\d\d\d$}

    (This pattern doesn't catch invalid days, but let's keep it for the
    example's purposes).

    We would like to validate the input with this regular expression \e{while}
    the user is typing it, so that we can report an error in the input as soon
    as it is committed (for instance, the user typed the wrong key). In order
    to do so we must distinguish three cases:

    \list
    \li the input cannot possibly match the regular expression;
    \li the input does match the regular expression;
    \li the input does not match the regular expression right now,
    but it will if more characters will be added to it.
    \endlist

    Note that these three cases represent exactly the possible states of a
    QValidator (see the QValidator::State enum).

    In particular, in the last case we want the regular expression engine to
    report a partial match: we are successfully matching the pattern against
    the subject string but the matching cannot continue because the end of the
    subject is encountered. Notice, however, that the matching algorithm should
    continue and try all possibilities, and in case a complete (non-partial)
    match is found, then this one should be reported, and the input string
    accepted as fully valid.

    This behaviour is implemented by the PartialPreferCompleteMatch match type.
    For instance:

    \snippet code/src_corelib_tools_qregularexpression.cpp 15

    If matching the same regular expression against the subject string leads to
    a complete match, it is reported as usual:

    \snippet code/src_corelib_tools_qregularexpression.cpp 16

    Another example with a different pattern, showing the behaviour of
    preferring a complete match over a partial one:

    \snippet code/src_corelib_tools_qregularexpression.cpp 17

    In this case, the subpattern \c{abc\\w+X} partially matches the subject
    string; however, the subpattern \c{def} matches the subject string
    completely, and therefore a complete match is reported.

    If multiple partial matches are found when matching (but no complete
    match), then the QRegularExpressionMatch object will report the first one
    that is found. For instance:

    \snippet code/src_corelib_tools_qregularexpression.cpp 18

    \section2 Incremental/multi-segment matching

    Incremental matching is another use case of partial matching. Suppose that
    we want to find the occurrences of a regular expression inside a large text
    (that is, substrings matching the regular expression). In order to do so we
    would like to "feed" the large text to the regular expression engines in
    smaller chunks. The obvious problem is what happens if the substring that
    matches the regular expression spans across two or more chunks.

    In this case, the regular expression engine should report a partial match,
    so that we can match again adding new data and (eventually) get a complete
    match. This implies that the regular expression engine may assume that
    there are other characters \e{beyond the end} of the subject string. This
    is not to be taken literally -- the engine will never try to access
    any character after the last one in the subject.

    QRegularExpression implements this behaviour when using the
    PartialPreferFirstMatch match type. This match type reports a partial match
    as soon as it is found, and other match alternatives are not tried
    (even if they could lead to a complete match). For instance:

    \snippet code/src_corelib_tools_qregularexpression.cpp 19

    This happens because when matching the first branch of the alternation
    operator a partial match is found, and therefore matching stops, without
    trying the second branch. Another example:

    \snippet code/src_corelib_tools_qregularexpression.cpp 20

    This shows what could seem a counterintuitve behaviour of quantifiers:
    since \c{?} is greedy, then the engine tries first to continue the match
    after having matched \c{"abc"}; but then the matching reaches the end of the
    subject string, and therefore a partial match is reported. This is
    even more surprising in the following example:

    \snippet code/src_corelib_tools_qregularexpression.cpp 21

    It's easy to understand this behaviour if we remember that the engine
    expects the subject string to be only a substring of the whole text we're
    looking for a match into (that is, how we said before, that the engine
    assumes that there are other characters beyond the end of the subject
    string).

    Since the \c{*} quantifier is greedy, then reporting a complete match could
    be an error, because after the current subject \c{"abc"} there may be other
    occurrences of \c{"abc"}. For instance, the complete text could have been
    "abcabcX", and therefore the \e{right} match to report (in the complete
    text) would have been \c{"abcabc"}; by matching only against the leading
    \c{"abc"} we instead get a partial match.

    \section1 Error handling

    It is possible for a QRegularExpression object to be invalid because of
    syntax errors in the pattern string. The isValid() function will return
    true if the regular expression is valid, or false otherwise:

    \snippet code/src_corelib_tools_qregularexpression.cpp 22

    You can get more information about the specific error by calling the
    errorString() function; moreover, the patternErrorOffset() function
    will return the offset inside the pattern string

    \snippet code/src_corelib_tools_qregularexpression.cpp 23

    If a match is attempted with an invalid QRegularExpression, then the
    returned QRegularExpressionMatch object will be invalid as well (that is,
    its \l{QRegularExpressionMatch::}{isValid()} function will return false).
    The same applies for attempting a global match.

    \section1 Unsupported Perl-compatible regular expressions features

    QRegularExpression does not support all the features available in
    Perl-compatible regular expressions. The most notable one is the fact that
    duplicated names for capturing groups are not supported, and using them can
    lead to undefined behaviour.

    This may change in a future version of Qt.

    \section1 Notes for QRegExp users

    The QRegularExpression class introduced in Qt 5 is a big improvement upon
    QRegExp, in terms of APIs offered, supported pattern syntax and speed of
    execution. The biggest difference is that QRegularExpression simply holds a
    regular expression, and it's \e{not} modified when a match is requested.
    Instead, a QRegularExpressionMatch object is returned, in order to check
    the result of a match and extract the captured substring. The same applies
    with global matching and QRegularExpressionMatchIterator.

    Other differences are outlined below.

    \section2 Exact matching

    QRegExp::exactMatch() in Qt 4 served two purposes: it exactly matched
    a regular expression against a subject string, and it implemented partial
    matching. In fact, if an exact match was not found, one could still find
    out how much of the subject string was matched by the regular expression
    by calling QRegExp::matchedLength(). If the returned length was equal
    to the subject string's length, then one could desume that a partial match
    was found.

    QRegularExpression supports partial matching explicitly by means of the
    appropriate MatchType. If instead you simply want to be sure that the
    subject string matches the regular expression exactly, you can wrap the
    pattern between a couple of anchoring expressions. Simply
    putting the pattern between the \c{^} and the \c{$} anchors is enough
    in most cases:

    \snippet code/src_corelib_tools_qregularexpression.cpp 24

    However, remember that the \c{$} anchor not only matches at the end of the
    string, but also at a newline character right before the end of the string;
    that is, the previous pattern matches against the string "this pattern must
    match exactly\\n". Also, the behaviour of both the \c{^} and the \c{$}
    anchors changes if the MultiLineOption is set either explicitly (as a
    pattern option) or implicitly (as a directive inside the pattern string).

    Therefore, in the most general case, you should wrap the pattern between
    the \c{\A} and the \c{\z} anchors:

    \snippet code/src_corelib_tools_qregularexpression.cpp 25

    Note the usage of the non-capturing group in order to preserve the meaning
    of the branch operator inside the pattern.

    \section2 Global matching

    Due to limitations of the QRegExp API it was impossible to implement global
    matching correctly (that is, like Perl does). In particular, patterns that
    can match 0 characters (like \c{"a*"}) are problematic.

    QRegularExpression::globalMatch() implements Perl global match correctly, and
    the returned iterator can be used to examine each result.

    \section2 Unicode properties support

    When using QRegExp, character classes such as \c{\w}, \c{\d}, etc. match
    characters with the corresponding Unicode property: for instance, \c{\d}
    matches any character with the Unicode Nd (decimal digit) property.

    Those character classes only match ASCII characters by default when using
    QRegularExpression: for instance, \c{\d} matches exactly a character in the
    \c{0-9} ASCII range. It is possible to change this behaviour by using the
    UseUnicodePropertiesOption pattern option.

    \section2 Wildcard matching

    There is no equivalent of wildcard matching in QRegularExpression.
    Nevertheless, rewriting a regular expression in wildcard syntax to a
    Perl-compatible regular expression is a very easy task, given the fact
    that wildcard syntax supported by QRegExp is very simple.

    \section2 Other pattern syntaxes

    QRegularExpression supports only Perl-compatible regular expressions.

    \section2 Minimal matching

    QRegExp::setMinimal() implemented minimal matching by simply reversing the
    greediness of the quantifiers (QRegExp did not support lazy quantifiers,
    like \c{*?}, \c{+?}, etc.). QRegularExpression instead does support greedy,
    lazy and possessive quantifiers. The InvertedGreedinessOption
    pattern option can be useful to emulate the effects of QRegExp::setMinimal():
    if enabled, it inverts the greediness of quantifiers (greedy ones become
    lazy and vice versa).

    \section2 Caret modes

    The AnchoredMatchOption match option can be used to emulate the
    QRegExp::CaretAtOffset behaviour. There is no equivalent for the other
    QRegExp::CaretMode modes.

    \section1 Debugging code that uses QRegularExpression

    QRegularExpression internally uses a just in time compiler (JIT) to
    optimize the execution of the matching algorithm. The JIT makes extensive
    usage of self-modifying code, which can lead debugging tools such as
    Valgrind to crash. You must enable all checks for self-modifying code if
    you want to debug programs using QRegularExpression (f.i., see Valgrind's
    \c{--smc-check} command line option). The downside of enabling such checks
    is that your program will run considerably slower.

    To avoid that, the JIT is disabled by default if you compile Qt in debug
    mode. It is possible to override the default and enable or disable the JIT
    usage (both in debug or release mode) by setting the
    \c{QT_ENABLE_REGEXP_JIT} environment variable to a non-zero or zero value
    respectively.

    \sa QRegularExpressionMatch, QRegularExpressionMatchIterator
*/

/*!
    \class QRegularExpressionMatch
    \inmodule QtCore
    \reentrant

    \brief The QRegularExpressionMatch class provides the results of a matching
    a QRegularExpression against a string.

    \since 5.0

    \ingroup tools
    \ingroup shared

    \keyword regular expression match

    A QRegularExpressionMatch object can be obtained by calling the
    QRegularExpression::match() function, or as a single result of a global
    match from a QRegularExpressionMatchIterator.

    The success or the failure of a match attempt can be inspected by calling
    the hasMatch() function. QRegularExpressionMatch also reports a successful
    partial match through the hasPartialMatch() function.

    In addition, QRegularExpressionMatch returns the substrings captured by the
    capturing groups in the pattern string. The implicit capturing group with
    index 0 captures the result of the whole match. The captured() function
    returns each substring captured, either by the capturing group's index or
    by its name:

    \snippet code/src_corelib_tools_qregularexpression.cpp 29

    For each captured substring it is possible to query its starting and ending
    offsets in the subject string by calling the capturedStart() and the
    capturedEnd() function, respectively. The length of each captured
    substring is available using the capturedLength() function.

    The convenience function capturedTexts() will return \e{all} the captured
    substrings at once (including the substring matched by the entire pattern)
    in the order they have been captured by captring groups; that is,
    \c{captured(i) == capturedTexts().at(i)}.

    You can retrieve the QRegularExpression object the subject string was
    matched against by calling the regularExpression() function; the
    match type and the match options are available as well by calling
    the matchType() and the matchOptions() respectively.

    Please refer to the QRegularExpression documentation for more information
    about the Qt regular expression classes.

    \sa QRegularExpression
*/

/*!
    \class QRegularExpressionMatchIterator
    \inmodule QtCore
    \reentrant

    \brief The QRegularExpressionMatchIterator class provides an iterator on
    the results of a global match of a QRegularExpression object against a string.

    \since 5.0

    \ingroup tools
    \ingroup shared

    \keyword regular expression iterator

    A QRegularExpressionMatchIterator object is a forward only Java-like
    iterator; it can be obtained by calling the
    QRegularExpression::globalMatch() function. A new
    QRegularExpressionMatchIterator will be positioned before the first result.
    You can then call the hasNext() function to check if there are more
    results available; if so, the next() function will return the next
    result and advance the iterator.

    Each result is a QRegularExpressionMatch object holding all the information
    for that result (including captured substrings).

    For instance:

    \snippet code/src_corelib_tools_qregularexpression.cpp 30

    Moreover, QRegularExpressionMatchIterator offers a peekNext() function
    to get the next result \e{without} advancing the iterator.

    You can retrieve the QRegularExpression object the subject string was
    matched against by calling the regularExpression() function; the
    match type and the match options are available as well by calling
    the matchType() and the matchOptions() respectively.

    Please refer to the QRegularExpression documentation for more information
    about the Qt regular expression classes.

    \sa QRegularExpression, QRegularExpressionMatch
*/


/*!
    \enum QRegularExpression::PatternOption

    The PatternOption enum defines modifiers to the way the pattern string
    should be interpreted, and therefore the way the pattern matches against a
    subject string.

    \value NoPatternOption
        No pattern options are set.

    \value CaseInsensitiveOption
        The pattern should match against the subject string in a case
        insensitive way. This option corresponds to the /i modifier in Perl
        regular expressions.

    \value DotMatchesEverythingOption
        The dot metacharacter (\c{.}) in the pattern string is allowed to match
        any character in the subject string, including newlines (normally, the
        dot does not match newlines). This option corresponds to the \c{/s}
        modifier in Perl regular expressions.

    \value MultilineOption
        The caret (\c{^}) and the dollar (\c{$}) metacharacters in the pattern
        string are allowed to match, respectively, immediately after and
        immediately before any newline in the subject string, as well as at the
        very beginning and at the very end of the subject string. This option
        corresponds to the \c{/m} modifier in Perl regular expressions.

    \value ExtendedPatternSyntaxOption
        Any whitespace in the pattern string which is not escaped and outside a
        character class is ignored. Moreover, an unescaped sharp (\b{#})
        outside a character class causes all the following characters, until
        the first newline (included), to be ignored. This can be used to
        increase the readability of a pattern string as well as put comments
        inside regular expressions; this is particulary useful if the pattern
        string is loaded from a file or written by the user, because in C++
        code it is always possible to use the rules for string literals to put
        comments outside the pattern string. This option corresponds to the \c{/x}
        modifier in Perl regular expressions.

    \value InvertedGreedinessOption
        The greediness of the quantifiers is inverted: \c{*}, \c{+}, \c{?},
        \c{{m,n}}, etc. become lazy, while their lazy versions (\c{*?},
        \c{+?}, \c{??}, \c{{m,n}?}, etc.) become greedy. There is no equivalent
        for this option in Perl regular expressions.

    \value DontCaptureOption
        The non-named capturing groups do not capture substrings; named
        capturing groups still work as intended, as well as the implicit
        capturing group number 0 corresponding to the entire match. There is no
        equivalent for this option in Perl regular expressions.

    \value UseUnicodePropertiesOption
        The meaning of the \c{\w}, \c{\d}, etc., character classes, as well as
        the meaning of their counterparts (\c{\W}, \c{\D}, etc.), is changed
        from matching ASCII characters only to matching any character with the
        corresponding Unicode property. For instance, \c{\d} is changed to
        match any character with the Unicode Nd (decimal digit) property;
        \c{\w} to match any character with either the Unicode L (letter) or N
        (digit) property, plus underscore, and so on. This option corresponds
        to the \c{/u} modifier in Perl regular expressions.
*/

/*!
    \enum QRegularExpression::MatchType

    The MatchType enum defines the type of the match that should be attempted
    against the subject string.

    \value NormalMatch
        A normal match is done.

    \value PartialPreferCompleteMatch
        The pattern string is matched partially against the subject string. If
        a partial match is found, then it is recorded, and other matching
        alternatives are tried as usual. If a complete match is then found,
        then it's preferred to the partial match; in this case only the
        complete match is reported. If instead no complete match is found (but
        only the partial one), then the partial one is reported.

    \value PartialPreferFirstMatch
        The pattern string is matched partially against the subject string. If
        a partial match is found, then matching stops and the partial match is
        reported. In this case, other matching alternatives (potentially
        leading to a complete match) are not tried. Moreover, this match type
        assumes that the subject string only a substring of a larger text, and
        that (in this text) there are other characters beyond the end of the
        subject string. This can lead to surprising results; see the discussion
        in the \l{partial matching} section for more details.

    \value NoMatch
        No matching is done. This value is returned as the match type by a
        default constructed QRegularExpressionMatch or
        QRegularExpressionMatchIterator. Using this match type is not very
        useful for the user, as no matching ever happens. This enum value
        has been introduced in Qt 5.1.
*/

/*!
    \enum QRegularExpression::MatchOption

    \value NoMatchOption
        No match options are set.

    \value AnchoredMatchOption
        The match is constrained to start exactly at the offset passed to
        match() in order to be successful, even if the pattern string does not
        contain any metacharacter that anchors the match at that point.
*/

// after how many usages we optimize the regexp
#ifdef QT_BUILD_INTERNAL
Q_AUTOTEST_EXPORT unsigned int qt_qregularexpression_optimize_after_use_count = 10;
#else
static const unsigned int qt_qregularexpression_optimize_after_use_count = 10;
#endif // QT_BUILD_INTERNAL

/*!
    \internal
*/
static int convertToPcreOptions(QRegularExpression::PatternOptions patternOptions)
{
    int options = 0;

    if (patternOptions & QRegularExpression::CaseInsensitiveOption)
        options |= PCRE_CASELESS;
    if (patternOptions & QRegularExpression::DotMatchesEverythingOption)
        options |= PCRE_DOTALL;
    if (patternOptions & QRegularExpression::MultilineOption)
        options |= PCRE_MULTILINE;
    if (patternOptions & QRegularExpression::ExtendedPatternSyntaxOption)
        options |= PCRE_EXTENDED;
    if (patternOptions & QRegularExpression::InvertedGreedinessOption)
        options |= PCRE_UNGREEDY;
    if (patternOptions & QRegularExpression::DontCaptureOption)
        options |= PCRE_NO_AUTO_CAPTURE;
    if (patternOptions & QRegularExpression::UseUnicodePropertiesOption)
        options |= PCRE_UCP;

    return options;
}

/*!
    \internal
*/
static int convertToPcreOptions(QRegularExpression::MatchOptions matchOptions)
{
    int options = 0;

    if (matchOptions & QRegularExpression::AnchoredMatchOption)
        options |= PCRE_ANCHORED;

    return options;
}

struct QRegularExpressionPrivate : QSharedData
{
    QRegularExpressionPrivate();
    ~QRegularExpressionPrivate();
    QRegularExpressionPrivate(const QRegularExpressionPrivate &other);

    void cleanCompiledPattern();
    void compilePattern();
    void getPatternInfo();
    pcre16_extra *optimizePattern();

    QRegularExpressionMatchPrivate *doMatch(const QString &subject,
                                            int offset,
                                            QRegularExpression::MatchType matchType,
                                            QRegularExpression::MatchOptions matchOptions,
                                            bool checkSubjectString = true,
                                            const QRegularExpressionMatchPrivate *previous = 0) const;

    int captureIndexForName(const QString &name) const;

    QString pattern;
    QRegularExpression::PatternOptions patternOptions;

    // *All* of the following members are set managed while holding this mutex,
    // except for isDirty which is set to true by QRegularExpression setters
    // (right after a detach happened).
    // On the other hand, after the compilation and studying,
    // it's safe to *use* (i.e. read) them from multiple threads at the same time.
    // Therefore, doMatch doesn't need to lock this mutex.
    QMutex mutex;

    // The PCRE pointers are reference-counted by the QRegularExpressionPrivate
    // objects themselves; when the private is copied (i.e. a detach happened)
    // they are set to 0
    pcre16 *compiledPattern;
    pcre16_extra *studyData;
    const char *errorString;
    int errorOffset;
    int capturingCount;
    unsigned int usedCount;
    bool usingCrLfNewlines;
    bool isDirty;
};

struct QRegularExpressionMatchPrivate : QSharedData
{
    QRegularExpressionMatchPrivate(const QRegularExpression &re,
                                   const QString &subject,
                                   QRegularExpression::MatchType matchType,
                                   QRegularExpression::MatchOptions matchOptions,
                                   int capturingCount = 0);

    QRegularExpressionMatch nextMatch() const;

    const QRegularExpression regularExpression;
    const QString subject;
    // the capturedOffsets vector contains pairs of (start, end) positions
    // for each captured substring
    QVector<int> capturedOffsets;

    const QRegularExpression::MatchType matchType;
    const QRegularExpression::MatchOptions matchOptions;

    int capturedCount;

    bool hasMatch;
    bool hasPartialMatch;
    bool isValid;
};

struct QRegularExpressionMatchIteratorPrivate : QSharedData
{
    QRegularExpressionMatchIteratorPrivate(const QRegularExpression &re,
                                           QRegularExpression::MatchType matchType,
                                           QRegularExpression::MatchOptions matchOptions,
                                           const QRegularExpressionMatch &next);

    bool hasNext() const;
    QRegularExpressionMatch next;
    const QRegularExpression regularExpression;
    const QRegularExpression::MatchType matchType;
    const QRegularExpression::MatchOptions matchOptions;
};

/*!
    \internal
*/
QRegularExpression::QRegularExpression(QRegularExpressionPrivate &dd)
    : d(&dd)
{
}

/*!
    \internal
*/
QRegularExpressionPrivate::QRegularExpressionPrivate()
    : pattern(), patternOptions(0),
      mutex(),
      compiledPattern(0), studyData(0),
      errorString(0), errorOffset(-1),
      capturingCount(0),
      usedCount(0),
      usingCrLfNewlines(false),
      isDirty(true)
{
}

/*!
    \internal
*/
QRegularExpressionPrivate::~QRegularExpressionPrivate()
{
    cleanCompiledPattern();
}

/*!
    \internal

    Copies the private, which means copying only the pattern and the pattern
    options. The compiledPattern and the studyData pointers are NOT copied (we
    do not own them any more), and in general all the members set when
    compiling a pattern are set to default values. isDirty is set back to true
    so that the pattern has to be recompiled again.
*/
QRegularExpressionPrivate::QRegularExpressionPrivate(const QRegularExpressionPrivate &other)
    : QSharedData(other),
      pattern(other.pattern), patternOptions(other.patternOptions),
      mutex(),
      compiledPattern(0), studyData(0),
      errorString(0),
      errorOffset(-1), capturingCount(0),
      usedCount(0),
      usingCrLfNewlines(false), isDirty(true)
{
}

/*!
    \internal
*/
void QRegularExpressionPrivate::cleanCompiledPattern()
{
    pcre16_free(compiledPattern);
    pcre16_free_study(studyData);
    usedCount = 0;
    compiledPattern = 0;
    studyData = 0;
    usingCrLfNewlines = false;
    errorOffset = -1;
    capturingCount = 0;
}

/*!
    \internal
*/
void QRegularExpressionPrivate::compilePattern()
{
    QMutexLocker lock(&mutex);

    if (!isDirty)
        return;

    isDirty = false;
    cleanCompiledPattern();

    int options = convertToPcreOptions(patternOptions);
    options |= PCRE_UTF16;

    int errorCode;
    compiledPattern = pcre16_compile2(pattern.utf16(), options,
                                      &errorCode, &errorString, &errorOffset, 0);

    if (!compiledPattern)
        return;

    Q_ASSERT(errorCode == 0);
    Q_ASSERT(studyData == 0); // studying (=>optimizing) is always done later
    errorOffset = -1;

    getPatternInfo();
}

/*!
    \internal
*/
void QRegularExpressionPrivate::getPatternInfo()
{
    Q_ASSERT(compiledPattern);

    pcre16_fullinfo(compiledPattern, 0, PCRE_INFO_CAPTURECOUNT, &capturingCount);

    // detect the settings for the newline
    unsigned long int patternNewlineSetting;
    pcre16_fullinfo(compiledPattern, studyData, PCRE_INFO_OPTIONS, &patternNewlineSetting);
    patternNewlineSetting &= PCRE_NEWLINE_CR  | PCRE_NEWLINE_LF | PCRE_NEWLINE_CRLF
            | PCRE_NEWLINE_ANY | PCRE_NEWLINE_ANYCRLF;
    if (patternNewlineSetting == 0) {
        // no option was specified in the regexp, grab PCRE build defaults
        int pcreNewlineSetting;
        pcre16_config(PCRE_CONFIG_NEWLINE, &pcreNewlineSetting);
        switch (pcreNewlineSetting) {
        case 13:
            patternNewlineSetting = PCRE_NEWLINE_CR; break;
        case 10:
            patternNewlineSetting = PCRE_NEWLINE_LF; break;
        case 3338: // (13<<8 | 10)
            patternNewlineSetting = PCRE_NEWLINE_CRLF; break;
        case -2:
            patternNewlineSetting = PCRE_NEWLINE_ANYCRLF; break;
        case -1:
            patternNewlineSetting = PCRE_NEWLINE_ANY; break;
        default:
            qWarning("QRegularExpressionPrivate::compilePattern(): "
                     "PCRE_CONFIG_NEWLINE returned an unknown newline");
            break;
        }
    }

    usingCrLfNewlines = (patternNewlineSetting == PCRE_NEWLINE_CRLF) ||
            (patternNewlineSetting == PCRE_NEWLINE_ANY) ||
            (patternNewlineSetting == PCRE_NEWLINE_ANYCRLF);
}


/*
    Simple "smartpointer" wrapper around a pcre_jit_stack, to be used with
    QThreadStorage.
*/
class QPcreJitStackPointer
{
    Q_DISABLE_COPY(QPcreJitStackPointer);

public:
    /*!
        \internal
    */
    QPcreJitStackPointer()
    {
        // The default JIT stack size in PCRE is 32K,
        // we allocate from 32K up to 512K.
        stack = pcre16_jit_stack_alloc(32*1024, 512*1024);
    }
    /*!
        \internal
    */
    ~QPcreJitStackPointer()
    {
        if (stack)
            pcre16_jit_stack_free(stack);
    }

    pcre16_jit_stack *stack;
};

Q_GLOBAL_STATIC(QThreadStorage<QPcreJitStackPointer *>, jitStacks)

/*!
    \internal
*/
static pcre16_jit_stack *qtPcreCallback(void *)
{
    if (jitStacks()->hasLocalData())
        return jitStacks()->localData()->stack;

    return 0;
}

/*!
    \internal
*/
static bool isJitEnabled()
{
    QByteArray jitEnvironment = qgetenv("QT_ENABLE_REGEXP_JIT");
    if (!jitEnvironment.isEmpty()) {
        bool ok;
        int enableJit = jitEnvironment.toInt(&ok);
        return ok ? (enableJit != 0) : true;
    }

#ifdef QT_DEBUG
    return false;
#else
    return true;
#endif
}

/*!
    \internal

    The purpose of the function is to call pcre16_study (which allows some
    optimizations to be performed, including JIT-compiling the pattern), and
    setting the studyData member variable to the result of the study. It gets
    called by doMatch() every time a match is performed. As of now, the
    optimizations on the pattern are performed after a certain number of usages
    (i.e. the qt_qregularexpression_optimize_after_use_count constant).

    Notice that although the method is protected by a mutex, one thread may
    invoke this function and return immediately (i.e. not study the pattern,
    leaving studyData to NULL); but before calling pcre16_exec to perform the
    match, another thread performs the studying and sets studyData to something
    else. Although the assignment to studyData is itself atomic, the release of
    the memory pointed by studyData isn't. Therefore, the current studyData
    value is returned and used by doMatch.
*/
pcre16_extra *QRegularExpressionPrivate::optimizePattern()
{
    Q_ASSERT(compiledPattern);

    QMutexLocker lock(&mutex);

    if (studyData || (++usedCount != qt_qregularexpression_optimize_after_use_count))
        return studyData;

    static const bool enableJit = isJitEnabled();

    int studyOptions = 0;
    if (enableJit)
        studyOptions |= PCRE_STUDY_JIT_COMPILE;

    const char *err;
    studyData = pcre16_study(compiledPattern, studyOptions, &err);

    if (studyData && studyData->flags & PCRE_EXTRA_EXECUTABLE_JIT)
        pcre16_assign_jit_stack(studyData, qtPcreCallback, 0);

    if (!studyData && err)
        qWarning("QRegularExpressionPrivate::optimizePattern(): pcre_study failed: %s", err);

    return studyData;
}

/*!
    \internal

    Returns the capturing group number for the given name. Duplicated names for
    capturing groups are not supported.
*/
int QRegularExpressionPrivate::captureIndexForName(const QString &name) const
{
    Q_ASSERT(!name.isEmpty());

    if (!compiledPattern)
        return -1;

    int index = pcre16_get_stringnumber(compiledPattern, name.utf16());
    if (index >= 0)
        return index;

    return -1;
}

/*!
    \internal

    This is a simple wrapper for pcre16_exec for handling the case in which the
    JIT runs out of memory. In that case, we allocate a thread-local JIT stack
    and re-run pcre16_exec.
*/
static int pcre16SafeExec(const pcre16 *code, const pcre16_extra *extra,
                          const unsigned short *subject, int length,
                          int startOffset, int options,
                          int *ovector, int ovecsize)
{
    int result = pcre16_exec(code, extra, subject, length,
                             startOffset, options, ovector, ovecsize);

    if (result == PCRE_ERROR_JIT_STACKLIMIT && !jitStacks()->hasLocalData()) {
        QPcreJitStackPointer *p = new QPcreJitStackPointer;
        jitStacks()->setLocalData(p);

        result = pcre16_exec(code, extra, subject, length,
                             startOffset, options, ovector, ovecsize);
    }

    return result;
}

/*!
    \internal

    Performs a match of type \a matchType on the given \a subject string with
    options \a matchOptions and returns the QRegularExpressionMatchPrivate of
    the result. It also advances a match if a previous result is given as \a
    previous. The \a subject string goes a Unicode validity check if
    \a checkSubjectString is true (PCRE doesn't like illegal UTF-16 sequences).

    Advancing a match is a tricky algorithm. If the previous match matched a
    non-empty string, we just do an ordinary match at the offset position.

    If the previous match matched an empty string, then an anchored, non-empty
    match is attempted at the offset position. If that succeeds, then we got
    the next match and we can return it. Otherwise, we advance by 1 position
    (which can be one or two code units in UTF-16!) and reattempt a "normal"
    match. We also have the problem of detecting the current newline format: if
    the new advanced offset is pointing to the beginning of a CRLF sequence, we
    must advance over it.
*/
QRegularExpressionMatchPrivate *QRegularExpressionPrivate::doMatch(const QString &subject,
                                                                   int offset,
                                                                   QRegularExpression::MatchType matchType,
                                                                   QRegularExpression::MatchOptions matchOptions,
                                                                   bool checkSubjectString,
                                                                   const QRegularExpressionMatchPrivate *previous) const
{
    if (offset < 0)
        offset += subject.length();

    QRegularExpression re(*const_cast<QRegularExpressionPrivate *>(this));

    if (offset < 0 || offset > subject.length())
        return new QRegularExpressionMatchPrivate(re, subject, matchType, matchOptions);

    if (!compiledPattern) {
        qWarning("QRegularExpressionPrivate::doMatch(): called on an invalid QRegularExpression object");
        return new QRegularExpressionMatchPrivate(re, subject, matchType, matchOptions);
    }

    // skip optimizing and doing the actual matching if NoMatch type was requested
    if (matchType == QRegularExpression::NoMatch) {
        QRegularExpressionMatchPrivate *priv = new QRegularExpressionMatchPrivate(re, subject,
                                                                                  matchType, matchOptions);
        priv->isValid = true;
        return priv;
    }

    // capturingCount doesn't include the implicit "0" capturing group
    QRegularExpressionMatchPrivate *priv = new QRegularExpressionMatchPrivate(re, subject,
                                                                              matchType, matchOptions,
                                                                              capturingCount + 1);

    // this is mutex protected
    const pcre16_extra *currentStudyData = const_cast<QRegularExpressionPrivate *>(this)->optimizePattern();

    int pcreOptions = convertToPcreOptions(matchOptions);

    if (matchType == QRegularExpression::PartialPreferCompleteMatch)
        pcreOptions |= PCRE_PARTIAL_SOFT;
    else if (matchType == QRegularExpression::PartialPreferFirstMatch)
        pcreOptions |= PCRE_PARTIAL_HARD;

    if (!checkSubjectString)
        pcreOptions |= PCRE_NO_UTF16_CHECK;

    bool previousMatchWasEmpty = false;
    if (previous && previous->hasMatch &&
            (previous->capturedOffsets.at(0) == previous->capturedOffsets.at(1))) {
        previousMatchWasEmpty = true;
    }

    int * const captureOffsets = priv->capturedOffsets.data();
    const int captureOffsetsCount = priv->capturedOffsets.size();

    const unsigned short * const subjectUtf16 = subject.utf16();
    const int subjectLength = subject.length();

    int result;

    if (!previousMatchWasEmpty) {
        result = pcre16SafeExec(compiledPattern, currentStudyData,
                                subjectUtf16, subjectLength,
                                offset, pcreOptions,
                                captureOffsets, captureOffsetsCount);
    } else {
        result = pcre16SafeExec(compiledPattern, currentStudyData,
                                subjectUtf16, subjectLength,
                                offset, pcreOptions | PCRE_NOTEMPTY_ATSTART | PCRE_ANCHORED,
                                captureOffsets, captureOffsetsCount);

        if (result == PCRE_ERROR_NOMATCH) {
            ++offset;

            if (usingCrLfNewlines
                    && offset < subjectLength
                    && subjectUtf16[offset - 1] == QLatin1Char('\r')
                    && subjectUtf16[offset] == QLatin1Char('\n')) {
                ++offset;
            } else if (offset < subjectLength
                       && QChar::isLowSurrogate(subjectUtf16[offset])) {
                ++offset;
            }

            result = pcre16SafeExec(compiledPattern, currentStudyData,
                                    subjectUtf16, subjectLength,
                                    offset, pcreOptions,
                                    captureOffsets, captureOffsetsCount);
        }
    }

#ifdef QREGULAREXPRESSION_DEBUG
    qDebug() << "Matching" <<  pattern << "against" << subject
             << offset << matchType << matchOptions << previousMatchWasEmpty
             << "result" << result;
#endif

    // result == 0 means not enough space in captureOffsets; should never happen
    Q_ASSERT(result != 0);

    if (result > 0) {
        // full match
        priv->isValid = true;
        priv->hasMatch = true;
        priv->capturedCount = result;
        priv->capturedOffsets.resize(result * 2);
    } else {
        // no match, partial match or error
        priv->hasPartialMatch = (result == PCRE_ERROR_PARTIAL);
        priv->isValid = (result == PCRE_ERROR_NOMATCH || result == PCRE_ERROR_PARTIAL);

        if (result == PCRE_ERROR_PARTIAL) {
            // partial match:
            // leave the start and end capture offsets (i.e. cap(0))
            priv->capturedCount = 1;
            priv->capturedOffsets.resize(2);
        } else {
            // no match or error
            priv->capturedCount = 0;
            priv->capturedOffsets.clear();
        }
    }

    return priv;
}

/*!
    \internal
*/
QRegularExpressionMatchPrivate::QRegularExpressionMatchPrivate(const QRegularExpression &re,
                                                               const QString &subject,
                                                               QRegularExpression::MatchType matchType,
                                                               QRegularExpression::MatchOptions matchOptions,
                                                               int capturingCount)
    : regularExpression(re), subject(subject),
      matchType(matchType), matchOptions(matchOptions),
      capturedCount(0),
      hasMatch(false), hasPartialMatch(false), isValid(false)
{
    Q_ASSERT(capturingCount >= 0);
    if (capturingCount > 0) {
        const int captureOffsetsCount = capturingCount * 3;
        capturedOffsets.resize(captureOffsetsCount);
    }
}


/*!
    \internal
*/
QRegularExpressionMatch QRegularExpressionMatchPrivate::nextMatch() const
{
    Q_ASSERT(isValid);
    Q_ASSERT(hasMatch || hasPartialMatch);

    // Note the "false" passed for the check of the subject string:
    // if we're advancing a match on the same subject,
    // then that subject was already checked at least once (when this object
    // was created, or when the object that created this one was created, etc.)
    QRegularExpressionMatchPrivate *nextPrivate = regularExpression.d->doMatch(subject,
                                                                               capturedOffsets.at(1),
                                                                               matchType,
                                                                               matchOptions,
                                                                               false,
                                                                               this);
    return QRegularExpressionMatch(*nextPrivate);
}

/*!
    \internal
*/
QRegularExpressionMatchIteratorPrivate::QRegularExpressionMatchIteratorPrivate(const QRegularExpression &re,
                                                                               QRegularExpression::MatchType matchType,
                                                                               QRegularExpression::MatchOptions matchOptions,
                                                                               const QRegularExpressionMatch &next)
    : next(next),
      regularExpression(re),
      matchType(matchType), matchOptions(matchOptions)
{
}

/*!
    \internal
*/
bool QRegularExpressionMatchIteratorPrivate::hasNext() const
{
    return next.isValid() && (next.hasMatch() || next.hasPartialMatch());
}

// PUBLIC API

/*!
    Constructs a QRegularExpression object with an empty pattern and no pattern
    options.

    \sa setPattern(), setPatternOptions()
*/
QRegularExpression::QRegularExpression()
    : d(new QRegularExpressionPrivate)
{
}

/*!
    Constructs a QRegularExpression object using the given \a pattern as
    pattern and the \a options as the pattern options.

    \sa setPattern(), setPatternOptions()
*/
QRegularExpression::QRegularExpression(const QString &pattern, PatternOptions options)
    : d(new QRegularExpressionPrivate)
{
    d->pattern = pattern;
    d->patternOptions = options;
}

/*!
    Constructs a QRegularExpression object as a copy of \a re.

    \sa operator=()
*/
QRegularExpression::QRegularExpression(const QRegularExpression &re)
    : d(re.d)
{
}

/*!
    Destroys the QRegularExpression object.
*/
QRegularExpression::~QRegularExpression()
{
}

/*!
    Assigns the regular expression \a re to this object, and returns a reference
    to the copy. Both the pattern and the pattern options are copied.
*/
QRegularExpression &QRegularExpression::operator=(const QRegularExpression &re)
{
    d = re.d;
    return *this;
}

/*!
    \fn void QRegularExpression::swap(QRegularExpression &other)

    Swaps the regular expression \a other with this regular expression. This
    operation is very fast and never fails.
*/

/*!
    Returns the pattern string of the regular expression.

    \sa setPattern(), patternOptions()
*/
QString QRegularExpression::pattern() const
{
    return d->pattern;
}

/*!
    Sets the pattern string of the regular expression to \a pattern. The
    pattern options are left unchanged.

    \sa pattern(), setPatternOptions()
*/
void QRegularExpression::setPattern(const QString &pattern)
{
    d.detach();
    d->isDirty = true;
    d->pattern = pattern;
}

/*!
    Returns the pattern options for the regular expression.

    \sa setPatternOptions(), pattern()
*/
QRegularExpression::PatternOptions QRegularExpression::patternOptions() const
{
    return d->patternOptions;
}

/*!
    Sets the given \a options as the pattern options of the regular expression.
    The pattern string is left unchanged.

    \sa patternOptions(), setPattern()
*/
void QRegularExpression::setPatternOptions(PatternOptions options)
{
    d.detach();
    d->isDirty = true;
    d->patternOptions = options;
}

/*!
    Returns the number of capturing groups inside the pattern string,
    or -1 if the regular expression is not valid.

    \sa isValid()
*/
int QRegularExpression::captureCount() const
{
    if (!isValid()) // will compile the pattern
        return -1;
    return d->capturingCount;
}

/*!
    Returns true if the regular expression is a valid regular expression (that
    is, it contains no syntax errors, etc.), or false otherwise. Use
    errorString() to obtain a textual description of the error.

    \sa errorString(), patternErrorOffset()
*/
bool QRegularExpression::isValid() const
{
    d.data()->compilePattern();
    return d->compiledPattern;
}

/*!
    Returns a textual description of the error found when checking the validity
    of the regular expression, or "no error" if no error was found.

    \sa isValid(), patternErrorOffset()
*/
QString QRegularExpression::errorString() const
{
    d.data()->compilePattern();
    if (d->errorString)
        return QCoreApplication::translate("QRegularExpression", d->errorString);
    return QCoreApplication::translate("QRegularExpression", "no error");
}

/*!
    Returns the offset, inside the pattern string, at which an error was found
    when checking the validity of the regular expression. If no error was
    found, then -1 is returned.

    \sa pattern(), isValid(), errorString()
*/
int QRegularExpression::patternErrorOffset() const
{
    d.data()->compilePattern();
    return d->errorOffset;
}

/*!
    Attempts to match the regular expression against the given \a subject
    string, starting at the position \a offset inside the subject, using a
    match of type \a matchType and honoring the given \a matchOptions.

    The returned QRegularExpressionMatch object contains the results of the
    match.

    \sa QRegularExpressionMatch, {normal matching}
*/
QRegularExpressionMatch QRegularExpression::match(const QString &subject,
                                                  int offset,
                                                  MatchType matchType,
                                                  MatchOptions matchOptions) const
{
    d.data()->compilePattern();

    QRegularExpressionMatchPrivate *priv = d->doMatch(subject, offset, matchType, matchOptions);
    return QRegularExpressionMatch(*priv);
}

/*!
    Attempts to perform a global match of the regular expression against the
    given \a subject string, starting at the position \a offset inside the
    subject, using a match of type \a matchType and honoring the given \a
    matchOptions.

    The returned QRegularExpressionMatchIterator is positioned before the
    first match result (if any).

    \sa QRegularExpressionMatchIterator, {global matching}
*/
QRegularExpressionMatchIterator QRegularExpression::globalMatch(const QString &subject,
                                                                int offset,
                                                                MatchType matchType,
                                                                MatchOptions matchOptions) const
{
    QRegularExpressionMatchIteratorPrivate *priv =
            new QRegularExpressionMatchIteratorPrivate(*this,
                                                       matchType,
                                                       matchOptions,
                                                       match(subject, offset, matchType, matchOptions));

    return QRegularExpressionMatchIterator(*priv);
}

/*!
    Returns true if the regular expression is equal to \a re, or false
    otherwise. Two QRegularExpression objects are equal if they have
    the same pattern string and the same pattern options.

    \sa operator!=()
*/
bool QRegularExpression::operator==(const QRegularExpression &re) const
{
    return (d == re.d) ||
           (d->pattern == re.d->pattern && d->patternOptions == re.d->patternOptions);
}

/*!
    \fn bool QRegularExpression::operator!=(const QRegularExpression &re) const

    Returns true if the regular expression is different from \a re, or
    false otherwise.

    \sa operator==()
*/

/*!
    Escapes all characters of \a str so that they no longer have any special
    meaning when used as a regular expression pattern string, and returns
    the escaped string. For instance:

    \snippet code/src_corelib_tools_qregularexpression.cpp 26

    This is very convenient in order to build patterns from arbitrary strings:

    \snippet code/src_corelib_tools_qregularexpression.cpp 27

    \note This function implements Perl's quotemeta algorithm and escapes with
    a backslash all characters in \a str, except for the characters in the
    \c{[A-Z]}, \c{[a-z]} and \c{[0-9]} ranges, as well as the underscore
    (\c{_}) character. The only difference with Perl is that a literal NUL
    inside \a str is escaped with the sequence \c{"\\0"} (backslash +
    \c{'0'}), instead of \c{"\\\0"} (backslash + \c{NUL}).
*/
QString QRegularExpression::escape(const QString &str)
{
    QString result;
    const int count = str.size();
    result.reserve(count * 2);

    // everything but [a-zA-Z0-9_] gets escaped,
    // cf. perldoc -f quotemeta
    for (int i = 0; i < count; ++i) {
        const QChar current = str.at(i);

        if (current == QChar::Null) {
            // unlike Perl, a literal NUL must be escaped with
            // "\\0" (backslash + 0) and not "\\\0" (backslash + NUL),
            // because pcre16_compile uses a NUL-terminated string
            result.append(QLatin1Char('\\'));
            result.append(QLatin1Char('0'));
        } else if ( (current < QLatin1Char('a') || current > QLatin1Char('z')) &&
                    (current < QLatin1Char('A') || current > QLatin1Char('Z')) &&
                    (current < QLatin1Char('0') || current > QLatin1Char('9')) &&
                     current != QLatin1Char('_') )
        {
            result.append(QLatin1Char('\\'));
            result.append(current);
            if (current.isHighSurrogate() && i < (count - 1))
                result.append(str.at(++i));
        } else {
            result.append(current);
        }
    }

    result.squeeze();
    return result;
}

/*!
    \since 5.1

    Constructs a valid, empty QRegularExpressionMatch object. The regular
    expression is set to a default-constructed one; the match type to
    QRegularExpression::NoMatch and the match options to
    QRegularExpression::NoMatchOption.

    The object will report no match through the hasMatch() and the
    hasPartialMatch() member functions.
*/
QRegularExpressionMatch::QRegularExpressionMatch()
    : d(new QRegularExpressionMatchPrivate(QRegularExpression(),
                                           QString(),
                                           QRegularExpression::NoMatch,
                                           QRegularExpression::NoMatchOption))
{
    d->isValid = true;
}

/*!
    Destroys the match result.
*/
QRegularExpressionMatch::~QRegularExpressionMatch()
{
}

/*!
    Constructs a match result by copying the result of the given \a match.

    \sa operator=()
*/
QRegularExpressionMatch::QRegularExpressionMatch(const QRegularExpressionMatch &match)
    : d(match.d)
{
}

/*!
    Assigns the match result \a match to this object, and returns a reference
    to the copy.
*/
QRegularExpressionMatch &QRegularExpressionMatch::operator=(const QRegularExpressionMatch &match)
{
    d = match.d;
    return *this;
}

/*!
    \fn void QRegularExpressionMatch::swap(QRegularExpressionMatch &other)

    Swaps the match result \a other with this match result. This
    operation is very fast and never fails.
*/

/*!
    \internal
*/
QRegularExpressionMatch::QRegularExpressionMatch(QRegularExpressionMatchPrivate &dd)
    : d(&dd)
{
}

/*!
    Returns the QRegularExpression object whose match() function returned this
    object.

    \sa QRegularExpression::match(), matchType(), matchOptions()
*/
QRegularExpression QRegularExpressionMatch::regularExpression() const
{
    return d->regularExpression;
}


/*!
    Returns the match type that was used to get this QRegularExpressionMatch
    object, that is, the match type that was passed to
    QRegularExpression::match() or QRegularExpression::globalMatch().

    \sa QRegularExpression::match(), regularExpression(), matchOptions()
*/
QRegularExpression::MatchType QRegularExpressionMatch::matchType() const
{
    return d->matchType;
}

/*!
    Returns the match options that were used to get this
    QRegularExpressionMatch object, that is, the match options that were passed
    to QRegularExpression::match() or QRegularExpression::globalMatch().

    \sa QRegularExpression::match(), regularExpression(), matchType()
*/
QRegularExpression::MatchOptions QRegularExpressionMatch::matchOptions() const
{
    return d->matchOptions;
}

/*!
    Returns the index of the last capturing group that captured something,
    including the implicit capturing group 0. This can be used to extract all
    the substrings that were captured:

    \snippet code/src_corelib_tools_qregularexpression.cpp 28

    Note that some of the capturing groups with an index less than
    lastCapturedIndex() could have not matched, and therefore captured nothing.

    If the regular expression did not match, this function returns -1.

    \sa captured(), capturedStart(), capturedEnd(), capturedLength()
*/
int QRegularExpressionMatch::lastCapturedIndex() const
{
    return d->capturedCount - 1;
}

/*!
    Returns the substring captured by the \a nth capturing group. If the \a nth
    capturing group did not capture a string or doesn't exist, returns a null
    QString.

    \sa capturedRef(), lastCapturedIndex(), capturedStart(), capturedEnd(),
    capturedLength(), QString::isNull()
*/
QString QRegularExpressionMatch::captured(int nth) const
{
    if (nth < 0 || nth > lastCapturedIndex())
        return QString();

    int start = capturedStart(nth);

    if (start == -1) // didn't capture
        return QString();

    return d->subject.mid(start, capturedLength(nth));
}

/*!
    Returns a reference to the substring captured by the \a nth capturing group.
    If the \a nth capturing group did not capture a string or doesn't exist,
    returns a null QStringRef.

    \sa captured(), lastCapturedIndex(), capturedStart(), capturedEnd(),
    capturedLength(), QStringRef::isNull()
*/
QStringRef QRegularExpressionMatch::capturedRef(int nth) const
{
    if (nth < 0 || nth > lastCapturedIndex())
        return QStringRef();

    int start = capturedStart(nth);

    if (start == -1) // didn't capture
        return QStringRef();

    return d->subject.midRef(start, capturedLength(nth));
}

/*!
    Returns the substring captured by the capturing group named \a name. If the
    capturing group named \a name did not capture a string or doesn't exist,
    returns a null QString.

    \sa capturedRef(), capturedStart(), capturedEnd(), capturedLength(),
    QString::isNull()
*/
QString QRegularExpressionMatch::captured(const QString &name) const
{
    if (name.isEmpty()) {
        qWarning("QRegularExpressionMatch::captured: empty capturing group name passed");
        return QString();
    }
    int nth = d->regularExpression.d->captureIndexForName(name);
    if (nth == -1)
        return QString();
    return captured(nth);
}

/*!
    Returns a reference to the string captured by the capturing group named \a
    name. If the capturing group named \a name did not capture a string or
    doesn't exist, returns a null QStringRef.

    \sa captured(), capturedStart(), capturedEnd(), capturedLength(),
    QStringRef::isNull()
*/
QStringRef QRegularExpressionMatch::capturedRef(const QString &name) const
{
    if (name.isEmpty()) {
        qWarning("QRegularExpressionMatch::capturedRef: empty capturing group name passed");
        return QStringRef();
    }
    int nth = d->regularExpression.d->captureIndexForName(name);
    if (nth == -1)
        return QStringRef();
    return capturedRef(nth);
}

/*!
    Returns a list of all strings captured by capturing groups, in the order
    the groups themselves appear in the pattern string.
*/
QStringList QRegularExpressionMatch::capturedTexts() const
{
    QStringList texts;
    for (int i = 0; i <= lastCapturedIndex(); ++i)
        texts << captured(i);
    return texts;
}

/*!
    Returns the offset inside the subject string corresponding to the
    starting position of the substring captured by the \a nth capturing group.
    If the \a nth capturing group did not capture a string or doesn't exist,
    returns -1.

    \sa capturedEnd(), capturedLength(), captured()
*/
int QRegularExpressionMatch::capturedStart(int nth) const
{
    if (nth < 0 || nth > lastCapturedIndex())
        return -1;

    return d->capturedOffsets.at(nth * 2);
}

/*!
    Returns the length of the substring captured by the \a nth capturing group.

    \note This function returns 0 if the \a nth capturing group did not capture
    a string or doesn't exist.

    \sa capturedStart(), capturedEnd(), captured()
*/
int QRegularExpressionMatch::capturedLength(int nth) const
{
    // bound checking performed by these two functions
    return capturedEnd(nth) - capturedStart(nth);
}

/*!
    Returns the offset inside the subject string immediately after the ending
    position of the substring captured by the \a nth capturing group. If the \a
    nth capturing group did not capture a string or doesn't exist, returns -1.

    \sa capturedStart(), capturedLength(), captured()
*/
int QRegularExpressionMatch::capturedEnd(int nth) const
{
    if (nth < 0 || nth > lastCapturedIndex())
        return -1;

    return d->capturedOffsets.at(nth * 2 + 1);
}

/*!
    Returns the offset inside the subject string corresponding to the starting
    position of the substring captured by the capturing group named \a name.
    If the capturing group named \a name did not capture a string or doesn't
    exist, returns -1.

    \sa capturedEnd(), capturedLength(), captured()
*/
int QRegularExpressionMatch::capturedStart(const QString &name) const
{
    if (name.isEmpty()) {
        qWarning("QRegularExpressionMatch::capturedStart: empty capturing group name passed");
        return -1;
    }
    int nth = d->regularExpression.d->captureIndexForName(name);
    if (nth == -1)
        return -1;
    return capturedStart(nth);
}

/*!
    Returns the offset inside the subject string corresponding to the starting
    position of the substring captured by the capturing group named \a name.

    \note This function returns 0 if the capturing group named \a name did not
    capture a string or doesn't exist.

    \sa capturedStart(), capturedEnd(), captured()
*/
int QRegularExpressionMatch::capturedLength(const QString &name) const
{
    if (name.isEmpty()) {
        qWarning("QRegularExpressionMatch::capturedLength: empty capturing group name passed");
        return 0;
    }
    int nth = d->regularExpression.d->captureIndexForName(name);
    if (nth == -1)
        return 0;
    return capturedLength(nth);
}

/*!
    Returns the offset inside the subject string immediately after the ending
    position of the substring captured by the capturing group named \a name. If
    the capturing group named \a name did not capture a string or doesn't
    exist, returns -1.

    \sa capturedStart(), capturedLength(), captured()
*/
int QRegularExpressionMatch::capturedEnd(const QString &name) const
{
    if (name.isEmpty()) {
        qWarning("QRegularExpressionMatch::capturedEnd: empty capturing group name passed");
        return -1;
    }
    int nth = d->regularExpression.d->captureIndexForName(name);
    if (nth == -1)
        return -1;
    return capturedEnd(nth);
}

/*!
    Returns true if the regular expression matched against the subject string,
    or false otherwise.

    \sa QRegularExpression::match(), hasPartialMatch()
*/
bool QRegularExpressionMatch::hasMatch() const
{
    return d->hasMatch;
}

/*!
    Returns true if the regular expression partially matched against the
    subject string, or false otherwise.

    \note Only a match that explicitly used the one of the partial match types
    can yield a partial match. Still, if such a match succeeds totally, this
    function will return false, while hasMatch() will return true.

    \sa QRegularExpression::match(), QRegularExpression::MatchType, hasMatch()
*/
bool QRegularExpressionMatch::hasPartialMatch() const
{
    return d->hasPartialMatch;
}

/*!
    Returns true if the match object was obtained as a result from the
    QRegularExpression::match() function invoked on a valid QRegularExpression
    object; returns false if the QRegularExpression was invalid.

    \sa QRegularExpression::match(), QRegularExpression::isValid()
*/
bool QRegularExpressionMatch::isValid() const
{
    return d->isValid;
}

/*!
    \internal
*/
QRegularExpressionMatchIterator::QRegularExpressionMatchIterator(QRegularExpressionMatchIteratorPrivate &dd)
    : d(&dd)
{
}

/*!
    \since 5.1

    Constructs an empty, valid QRegularExpressionMatchIterator object. The
    regular expression is set to a default-constructed one; the match type to
    QRegularExpression::NoMatch and the match options to
    QRegularExpression::NoMatchOption.

    Invoking the hasNext() member function on the constructed object will
    return false, as the iterator is not iterating on a valid sequence of
    matches.
*/
QRegularExpressionMatchIterator::QRegularExpressionMatchIterator()
    : d(new QRegularExpressionMatchIteratorPrivate(QRegularExpression(),
                                                   QRegularExpression::NoMatch,
                                                   QRegularExpression::NoMatchOption,
                                                   QRegularExpressionMatch()))
{
}

/*!
    Destroys the QRegularExpressionMatchIterator object.
*/
QRegularExpressionMatchIterator::~QRegularExpressionMatchIterator()
{
}

/*!
    Constructs a QRegularExpressionMatchIterator object as a copy of \a
    iterator.

    \sa operator=()
*/
QRegularExpressionMatchIterator::QRegularExpressionMatchIterator(const QRegularExpressionMatchIterator &iterator)
    : d(iterator.d)
{
}

/*!
    Assigns the iterator \a iterator to this object, and returns a reference to
    the copy.
*/
QRegularExpressionMatchIterator &QRegularExpressionMatchIterator::operator=(const QRegularExpressionMatchIterator &iterator)
{
    d = iterator.d;
    return *this;
}

/*!
    \fn void QRegularExpressionMatchIterator::swap(QRegularExpressionMatchIterator &other)

    Swaps the iterator \a other with this iterator object. This operation is
    very fast and never fails.
*/

/*!
    Returns true if the iterator object was obtained as a result from the
    QRegularExpression::globalMatch() function invoked on a valid
    QRegularExpression object; returns false if the QRegularExpression was
    invalid.

    \sa QRegularExpression::globalMatch(), QRegularExpression::isValid()
*/
bool QRegularExpressionMatchIterator::isValid() const
{
    return d->next.isValid();
}

/*!
    Returns true if there is at least one match result ahead of the iterator;
    otherwise it returns false.

    \sa next()
*/
bool QRegularExpressionMatchIterator::hasNext() const
{
    return d->hasNext();
}

/*!
    Returns the next match result without moving the iterator.

    \note Calling this function when the iterator is at the end of the result
    set leads to undefined results.
*/
QRegularExpressionMatch QRegularExpressionMatchIterator::peekNext() const
{
    if (!hasNext())
        qWarning("QRegularExpressionMatchIterator::peekNext() called on an iterator already at end");

    return d->next;
}

/*!
    Returns the next match result and advances the iterator by one position.

    \note Calling this function when the iterator is at the end of the result
    set leads to undefined results.
*/
QRegularExpressionMatch QRegularExpressionMatchIterator::next()
{
    if (!hasNext()) {
        qWarning("QRegularExpressionMatchIterator::next() called on an iterator already at end");
        return d->next;
    }

    QRegularExpressionMatch current = d->next;
    d->next = d->next.d.constData()->nextMatch();
    return current;
}

/*!
    Returns the QRegularExpression object whose globalMatch() function returned
    this object.

    \sa QRegularExpression::globalMatch(), matchType(), matchOptions()
*/
QRegularExpression QRegularExpressionMatchIterator::regularExpression() const
{
    return d->regularExpression;
}

/*!
    Returns the match type that was used to get this
    QRegularExpressionMatchIterator object, that is, the match type that was
    passed to QRegularExpression::globalMatch().

    \sa QRegularExpression::globalMatch(), regularExpression(), matchOptions()
*/
QRegularExpression::MatchType QRegularExpressionMatchIterator::matchType() const
{
    return d->matchType;
}

/*!
    Returns the match options that were used to get this
    QRegularExpressionMatchIterator object, that is, the match options that
    were passed to QRegularExpression::globalMatch().

    \sa QRegularExpression::globalMatch(), regularExpression(), matchType()
*/
QRegularExpression::MatchOptions QRegularExpressionMatchIterator::matchOptions() const
{
    return d->matchOptions;
}

#ifndef QT_NO_DATASTREAM
/*!
    \relates QRegularExpression

    Writes the regular expression \a re to stream \a out.

    \sa {Serializing Qt Data Types}
*/
QDataStream &operator<<(QDataStream &out, const QRegularExpression &re)
{
    out << re.pattern() << quint32(re.patternOptions());
    return out;
}

/*!
    \relates QRegularExpression

    Reads a regular expression from stream \a in into \a re.

    \sa {Serializing Qt Data Types}
*/
QDataStream &operator>>(QDataStream &in, QRegularExpression &re)
{
    QString pattern;
    quint32 patternOptions;
    in >> pattern >> patternOptions;
    re.setPattern(pattern);
    re.setPatternOptions(QRegularExpression::PatternOptions(patternOptions));
    return in;
}
#endif

#ifndef QT_NO_DEBUG_STREAM
/*!
    \relates QRegularExpression

    Writes the regular expression \a re into the debug object \a debug for
    debugging purposes.

    \sa {Debugging Techniques}
*/
QDebug operator<<(QDebug debug, const QRegularExpression &re)
{
    debug.nospace() << "QRegularExpression(" << re.pattern() << ", " << re.patternOptions() << ")";
    return debug.space();
}

/*!
    \relates QRegularExpression

    Writes the pattern options \a patternOptions into the debug object \a debug
    for debugging purposes.

    \sa {Debugging Techniques}
*/
QDebug operator<<(QDebug debug, QRegularExpression::PatternOptions patternOptions)
{
    QByteArray flags;

    if (patternOptions == QRegularExpression::NoPatternOption) {
        flags = "NoPatternOption";
    } else {
        flags.reserve(200); // worst case...
        if (patternOptions & QRegularExpression::CaseInsensitiveOption)
            flags.append("CaseInsensitiveOption|");
        if (patternOptions & QRegularExpression::DotMatchesEverythingOption)
            flags.append("DotMatchesEverythingOption|");
        if (patternOptions & QRegularExpression::MultilineOption)
            flags.append("MultilineOption|");
        if (patternOptions & QRegularExpression::ExtendedPatternSyntaxOption)
            flags.append("ExtendedPatternSyntaxOption|");
        if (patternOptions & QRegularExpression::InvertedGreedinessOption)
            flags.append("InvertedGreedinessOption|");
        if (patternOptions & QRegularExpression::DontCaptureOption)
            flags.append("DontCaptureOption|");
        if (patternOptions & QRegularExpression::UseUnicodePropertiesOption)
            flags.append("UseUnicodePropertiesOption|");
        flags.chop(1);
    }

    debug.nospace() << "QRegularExpression::PatternOptions(" << flags << ")";

    return debug.space();
}
/*!
    \relates QRegularExpressionMatch

    Writes the match object \a match into the debug object \a debug for
    debugging purposes.

    \sa {Debugging Techniques}
*/
QDebug operator<<(QDebug debug, const QRegularExpressionMatch &match)
{
    debug.nospace() << "QRegularExpressionMatch(";

    if (!match.isValid()) {
        debug << "Invalid)";
        return debug.space();
    }

    debug << "Valid";

    if (match.hasMatch()) {
        debug << ", has match: ";
        for (int i = 0; i <= match.lastCapturedIndex(); ++i) {
            debug << i
                  << ":(" << match.capturedStart(i) << ", " << match.capturedEnd(i)
                  << ", " << match.captured(i) << ")";
            if (i < match.lastCapturedIndex())
                debug << ", ";
        }
    } else if (match.hasPartialMatch()) {
        debug << ", has partial match: ("
              << match.capturedStart(0) << ", "
              << match.capturedEnd(0) << ", "
              << match.captured(0) << ")";
    } else {
        debug << ", no match";
    }

    debug << ")";

    return debug.space();
}
#endif

// fool lupdate: make it extract those strings for translation, but don't put them
// inside Qt -- they're already inside libpcre (cf. man 3 pcreapi, pcre_compile.c).
#if 0

/* PCRE is a library of functions to support regular expressions whose syntax
and semantics are as close as possible to those of the Perl 5 language.

                       Written by Philip Hazel
           Copyright (c) 1997-2012 University of Cambridge

-----------------------------------------------------------------------------
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

    * Redistributions of source code must retain the above copyright notice,
      this list of conditions and the following disclaimer.

    * 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.

    * Neither the name of the University of Cambridge nor the names of its
      contributors may be used to endorse or promote products derived from
      this software without specific prior written permission.

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.
-----------------------------------------------------------------------------
*/

static const char *pcreCompileErrorCodes[] =
{
    QT_TRANSLATE_NOOP("QRegularExpression", "no error"),
    QT_TRANSLATE_NOOP("QRegularExpression", "\\ at end of pattern"),
    QT_TRANSLATE_NOOP("QRegularExpression", "\\c at end of pattern"),
    QT_TRANSLATE_NOOP("QRegularExpression", "unrecognized character follows \\"),
    QT_TRANSLATE_NOOP("QRegularExpression", "numbers out of order in {} quantifier"),
    QT_TRANSLATE_NOOP("QRegularExpression", "number too big in {} quantifier"),
    QT_TRANSLATE_NOOP("QRegularExpression", "missing terminating ] for character class"),
    QT_TRANSLATE_NOOP("QRegularExpression", "invalid escape sequence in character class"),
    QT_TRANSLATE_NOOP("QRegularExpression", "range out of order in character class"),
    QT_TRANSLATE_NOOP("QRegularExpression", "nothing to repeat"),
    QT_TRANSLATE_NOOP("QRegularExpression", "internal error: unexpected repeat"),
    QT_TRANSLATE_NOOP("QRegularExpression", "unrecognized character after (? or (?-"),
    QT_TRANSLATE_NOOP("QRegularExpression", "POSIX named classes are supported only within a class"),
    QT_TRANSLATE_NOOP("QRegularExpression", "missing )"),
    QT_TRANSLATE_NOOP("QRegularExpression", "reference to non-existent subpattern"),
    QT_TRANSLATE_NOOP("QRegularExpression", "erroffset passed as NULL"),
    QT_TRANSLATE_NOOP("QRegularExpression", "unknown option bit(s) set"),
    QT_TRANSLATE_NOOP("QRegularExpression", "missing ) after comment"),
    QT_TRANSLATE_NOOP("QRegularExpression", "regular expression is too large"),
    QT_TRANSLATE_NOOP("QRegularExpression", "failed to get memory"),
    QT_TRANSLATE_NOOP("QRegularExpression", "unmatched parentheses"),
    QT_TRANSLATE_NOOP("QRegularExpression", "internal error: code overflow"),
    QT_TRANSLATE_NOOP("QRegularExpression", "unrecognized character after (?<"),
    QT_TRANSLATE_NOOP("QRegularExpression", "lookbehind assertion is not fixed length"),
    QT_TRANSLATE_NOOP("QRegularExpression", "malformed number or name after (?("),
    QT_TRANSLATE_NOOP("QRegularExpression", "conditional group contains more than two branches"),
    QT_TRANSLATE_NOOP("QRegularExpression", "assertion expected after (?("),
    QT_TRANSLATE_NOOP("QRegularExpression", "(?R or (?[+-]digits must be followed by )"),
    QT_TRANSLATE_NOOP("QRegularExpression", "unknown POSIX class name"),
    QT_TRANSLATE_NOOP("QRegularExpression", "POSIX collating elements are not supported"),
    QT_TRANSLATE_NOOP("QRegularExpression", "this version of PCRE is not compiled with PCRE_UTF8 support"),
    QT_TRANSLATE_NOOP("QRegularExpression", "character value in \\x{...} sequence is too large"),
    QT_TRANSLATE_NOOP("QRegularExpression", "invalid condition (?(0)"),
    QT_TRANSLATE_NOOP("QRegularExpression", "\\C not allowed in lookbehind assertion"),
    QT_TRANSLATE_NOOP("QRegularExpression", "PCRE does not support \\L, \\l, \\N{name}, \\U, or \\u"),
    QT_TRANSLATE_NOOP("QRegularExpression", "number after (?C is > 255"),
    QT_TRANSLATE_NOOP("QRegularExpression", "closing ) for (?C expected"),
    QT_TRANSLATE_NOOP("QRegularExpression", "recursive call could loop indefinitely"),
    QT_TRANSLATE_NOOP("QRegularExpression", "unrecognized character after (?P"),
    QT_TRANSLATE_NOOP("QRegularExpression", "syntax error in subpattern name (missing terminator)"),
    QT_TRANSLATE_NOOP("QRegularExpression", "two named subpatterns have the same name"),
    QT_TRANSLATE_NOOP("QRegularExpression", "invalid UTF-8 string"),
    QT_TRANSLATE_NOOP("QRegularExpression", "support for \\P, \\p, and \\X has not been compiled"),
    QT_TRANSLATE_NOOP("QRegularExpression", "malformed \\P or \\p sequence"),
    QT_TRANSLATE_NOOP("QRegularExpression", "unknown property name after \\P or \\p"),
    QT_TRANSLATE_NOOP("QRegularExpression", "subpattern name is too long (maximum 32 characters)"),
    QT_TRANSLATE_NOOP("QRegularExpression", "too many named subpatterns (maximum 10000)"),
    QT_TRANSLATE_NOOP("QRegularExpression", "octal value is greater than \\377 (not in UTF-8 mode)"),
    QT_TRANSLATE_NOOP("QRegularExpression", "internal error: overran compiling workspace"),
    QT_TRANSLATE_NOOP("QRegularExpression", "internal error: previously-checked referenced subpattern not found"),
    QT_TRANSLATE_NOOP("QRegularExpression", "DEFINE group contains more than one branch"),
    QT_TRANSLATE_NOOP("QRegularExpression", "repeating a DEFINE group is not allowed"),
    QT_TRANSLATE_NOOP("QRegularExpression", "inconsistent NEWLINE options"),
    QT_TRANSLATE_NOOP("QRegularExpression", "\\g is not followed by a braced, angle-bracketed, or quoted name/number or by a plain number"),
    QT_TRANSLATE_NOOP("QRegularExpression", "a numbered reference must not be zero"),
    QT_TRANSLATE_NOOP("QRegularExpression", "an argument is not allowed for (*ACCEPT), (*FAIL), or (*COMMIT)"),
    QT_TRANSLATE_NOOP("QRegularExpression", "(*VERB) not recognized"),
    QT_TRANSLATE_NOOP("QRegularExpression", "number is too big"),
    QT_TRANSLATE_NOOP("QRegularExpression", "subpattern name expected"),
    QT_TRANSLATE_NOOP("QRegularExpression", "digit expected after (?+"),
    QT_TRANSLATE_NOOP("QRegularExpression", "] is an invalid data character in JavaScript compatibility mode"),
    QT_TRANSLATE_NOOP("QRegularExpression", "different names for subpatterns of the same number are not allowed"),
    QT_TRANSLATE_NOOP("QRegularExpression", "(*MARK) must have an argument"),
    QT_TRANSLATE_NOOP("QRegularExpression", "this version of PCRE is not compiled with PCRE_UCP support"),
    QT_TRANSLATE_NOOP("QRegularExpression", "\\c must be followed by an ASCII character"),
    QT_TRANSLATE_NOOP("QRegularExpression", "\\k is not followed by a braced, angle-bracketed, or quoted name"),
    QT_TRANSLATE_NOOP("QRegularExpression", "internal error: unknown opcode in find_fixedlength()"),
    QT_TRANSLATE_NOOP("QRegularExpression", "\\N is not supported in a class"),
    QT_TRANSLATE_NOOP("QRegularExpression", "too many forward references"),
    QT_TRANSLATE_NOOP("QRegularExpression", "disallowed Unicode code point (>= 0xd800 && <= 0xdfff)"),
    QT_TRANSLATE_NOOP("QRegularExpression", "invalid UTF-16 string"),
    QT_TRANSLATE_NOOP("QRegularExpression", "name is too long in (*MARK), (*PRUNE), (*SKIP), or (*THEN)"),
    QT_TRANSLATE_NOOP("QRegularExpression", "character value in \\u.... sequence is too large")
};
#endif // #if 0

QT_END_NAMESPACE