summaryrefslogtreecommitdiffstats
path: root/src/corelib/tools/qhash.cpp
blob: 3ff8f886f1f0e4679ffa3592208e43a8f859f150 (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
2414
2415
2416
2417
2418
2419
2420
2421
2422
2423
2424
2425
2426
2427
2428
2429
2430
2431
2432
2433
2434
2435
2436
2437
2438
2439
2440
2441
2442
2443
2444
2445
2446
2447
2448
2449
2450
2451
2452
2453
2454
2455
2456
2457
2458
2459
2460
2461
2462
2463
2464
2465
2466
2467
2468
2469
2470
2471
2472
2473
2474
2475
2476
2477
2478
2479
2480
2481
2482
2483
2484
2485
2486
2487
2488
2489
2490
2491
2492
2493
2494
2495
2496
2497
2498
2499
2500
2501
2502
2503
2504
2505
2506
2507
2508
2509
2510
2511
2512
2513
2514
2515
2516
2517
2518
2519
2520
2521
2522
2523
2524
2525
2526
2527
2528
2529
2530
2531
2532
2533
2534
2535
2536
2537
2538
2539
2540
2541
2542
2543
2544
2545
2546
2547
2548
2549
2550
2551
2552
2553
2554
2555
2556
2557
2558
2559
2560
2561
2562
2563
2564
2565
2566
2567
2568
2569
2570
2571
2572
2573
2574
2575
2576
2577
2578
2579
2580
2581
2582
2583
2584
2585
2586
2587
2588
2589
2590
2591
2592
2593
2594
2595
2596
2597
2598
2599
2600
2601
2602
2603
2604
2605
2606
2607
2608
2609
2610
2611
2612
2613
2614
2615
2616
2617
2618
2619
2620
2621
2622
2623
2624
2625
2626
2627
2628
2629
2630
2631
2632
2633
2634
2635
2636
2637
2638
2639
2640
2641
2642
2643
2644
2645
2646
2647
2648
2649
2650
2651
2652
2653
2654
2655
2656
2657
2658
2659
2660
2661
2662
2663
2664
2665
2666
2667
2668
2669
2670
2671
2672
2673
2674
2675
2676
2677
2678
2679
2680
2681
2682
2683
2684
2685
2686
2687
2688
2689
2690
2691
2692
2693
2694
2695
2696
2697
2698
2699
2700
2701
2702
2703
2704
2705
2706
2707
2708
2709
2710
2711
2712
2713
2714
2715
2716
2717
2718
2719
2720
2721
2722
2723
2724
2725
2726
2727
2728
2729
2730
2731
2732
2733
2734
2735
2736
2737
2738
2739
2740
2741
2742
2743
2744
2745
2746
2747
2748
2749
2750
2751
2752
2753
2754
2755
2756
2757
2758
2759
2760
2761
2762
2763
2764
/****************************************************************************
**
** Copyright (C) 2016 The Qt Company Ltd.
** Copyright (C) 2016 Intel Corporation.
** Copyright (C) 2012 Giuseppe D'Angelo <dangelog@gmail.com>.
** Contact: https://www.qt.io/licensing/
**
** 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 The Qt Company. For licensing terms
** and conditions see https://www.qt.io/terms-conditions. For further
** information use the contact form at https://www.qt.io/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 3 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL3 included in the
** packaging of this file. Please review the following information to
** ensure the GNU Lesser General Public License version 3 requirements
** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 2.0 or (at your option) the GNU General
** Public license version 3 or any later version approved by the KDE Free
** Qt Foundation. The licenses are as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
** included in the packaging of this file. Please review the following
** information to ensure the GNU General Public License requirements will
** be met: https://www.gnu.org/licenses/gpl-2.0.html and
** https://www.gnu.org/licenses/gpl-3.0.html.
**
** $QT_END_LICENSE$
**
****************************************************************************/

// for rand_s, _CRT_RAND_S must be #defined before #including stdlib.h.
// put it at the beginning so some indirect inclusion doesn't break it
#ifndef _CRT_RAND_S
#define _CRT_RAND_S
#endif
#include <stdlib.h>

#include "qhash.h"

#ifdef truncate
#undef truncate
#endif

#include <qbitarray.h>
#include <qstring.h>
#include <qglobal.h>
#include <qbytearray.h>
#include <qdatetime.h>
#include <qbasicatomic.h>
#include <qendian.h>
#include <private/qsimd_p.h>

#ifndef QT_BOOTSTRAPPED
#include <qcoreapplication.h>
#include <qrandom.h>
#endif // QT_BOOTSTRAPPED

#include <limits.h>

QT_BEGIN_NAMESPACE

/*
    The Java's hashing algorithm for strings is a variation of D. J. Bernstein
    hashing algorithm appeared here http://cr.yp.to/cdb/cdb.txt
    and informally known as DJB33XX - DJB's 33 Times Xor.
    Java uses DJB31XA, that is, 31 Times Add.

    The original algorithm was a loop around
        (h << 5) + h ^ c
    (which is indeed h*33 ^ c); it was then changed to
        (h << 5) - h ^ c
    (so h*31^c: DJB31XX), and the XOR changed to a sum:
        (h << 5) - h + c
    (DJB31XA), which can save some assembly instructions.

    Still, we can avoid writing the multiplication as "(h << 5) - h"
    -- the compiler will turn it into a shift and an addition anyway
    (for instance, gcc 4.4 does that even at -O0).
*/

#if QT_COMPILER_SUPPORTS_HERE(SSE4_2)
static inline bool hasFastCrc32()
{
    return qCpuHasFeature(SSE4_2);
}

template <typename Char>
QT_FUNCTION_TARGET(SSE4_2)
static uint crc32(const Char *ptr, size_t len, uint h)
{
    // The CRC32 instructions from Nehalem calculate a 32-bit CRC32 checksum
    const uchar *p = reinterpret_cast<const uchar *>(ptr);
    const uchar *const e = p + (len * sizeof(Char));
#  ifdef Q_PROCESSOR_X86_64
    // The 64-bit instruction still calculates only 32-bit, but without this
    // variable GCC 4.9 still tries to clear the high bits on every loop
    qulonglong h2 = h;

    p += 8;
    for ( ; p <= e; p += 8)
        h2 = _mm_crc32_u64(h2, qFromUnaligned<qlonglong>(p - 8));
    h = h2;
    p -= 8;

    len = e - p;
    if (len & 4) {
        h = _mm_crc32_u32(h, qFromUnaligned<uint>(p));
        p += 4;
    }
#  else
    p += 4;
    for ( ; p <= e; p += 4)
        h = _mm_crc32_u32(h, qFromUnaligned<uint>(p - 4));
    p -= 4;
    len = e - p;
#  endif
    if (len & 2) {
        h = _mm_crc32_u16(h, qFromUnaligned<ushort>(p));
        p += 2;
    }
    if (sizeof(Char) == 1 && len & 1)
        h = _mm_crc32_u8(h, *p);
    return h;
}
#elif defined(__ARM_FEATURE_CRC32)
static inline bool hasFastCrc32()
{
    return qCpuHasFeature(CRC32);
}

template <typename Char>
#if defined(Q_PROCESSOR_ARM_64)
QT_FUNCTION_TARGET(CRC32)
#endif
static uint crc32(const Char *ptr, size_t len, uint h)
{
    // The crc32[whbd] instructions on Aarch64/Aarch32 calculate a 32-bit CRC32 checksum
    const uchar *p = reinterpret_cast<const uchar *>(ptr);
    const uchar *const e = p + (len * sizeof(Char));

#ifndef __ARM_FEATURE_UNALIGNED
    if (Q_UNLIKELY(reinterpret_cast<quintptr>(p) & 7)) {
        if ((sizeof(Char) == 1) && (reinterpret_cast<quintptr>(p) & 1) && (e - p > 0)) {
            h = __crc32b(h, *p);
            ++p;
        }
        if ((reinterpret_cast<quintptr>(p) & 2) && (e >= p + 2)) {
            h = __crc32h(h, *reinterpret_cast<const uint16_t *>(p));
            p += 2;
        }
        if ((reinterpret_cast<quintptr>(p) & 4) && (e >= p + 4)) {
            h = __crc32w(h, *reinterpret_cast<const uint32_t *>(p));
            p += 4;
        }
    }
#endif

    for ( ; p + 8 <= e; p += 8)
        h = __crc32d(h, *reinterpret_cast<const uint64_t *>(p));

    len = e - p;
    if (len == 0)
        return h;
    if (len & 4) {
        h = __crc32w(h, *reinterpret_cast<const uint32_t *>(p));
        p += 4;
    }
    if (len & 2) {
        h = __crc32h(h, *reinterpret_cast<const uint16_t *>(p));
        p += 2;
    }
    if (sizeof(Char) == 1 && len & 1)
        h = __crc32b(h, *p);
    return h;
}
#else
static inline bool hasFastCrc32()
{
    return false;
}

static uint crc32(...)
{
    Q_UNREACHABLE();
    return 0;
}
#endif

static inline uint hash(const uchar *p, size_t len, uint seed) noexcept
{
    uint h = seed;

    if (seed && hasFastCrc32())
        return crc32(p, len, h);

    for (size_t i = 0; i < len; ++i)
        h = 31 * h + p[i];

    return h;
}

uint qHashBits(const void *p, size_t len, uint seed) noexcept
{
    return hash(static_cast<const uchar*>(p), int(len), seed);
}

static inline uint hash(const QChar *p, size_t len, uint seed) noexcept
{
    uint h = seed;

    if (seed && hasFastCrc32())
        return crc32(p, len, h);

    for (size_t i = 0; i < len; ++i)
        h = 31 * h + p[i].unicode();

    return h;
}

uint qHash(const QByteArray &key, uint seed) noexcept
{
    return hash(reinterpret_cast<const uchar *>(key.constData()), size_t(key.size()), seed);
}

#if QT_STRINGVIEW_LEVEL < 2
uint qHash(const QString &key, uint seed) noexcept
{
    return hash(key.unicode(), size_t(key.size()), seed);
}

uint qHash(const QStringRef &key, uint seed) noexcept
{
    return hash(key.unicode(), size_t(key.size()), seed);
}
#endif

uint qHash(QStringView key, uint seed) noexcept
{
    return hash(key.data(), key.size(), seed);
}

uint qHash(const QBitArray &bitArray, uint seed) noexcept
{
    int m = bitArray.d.size() - 1;
    uint result = hash(reinterpret_cast<const uchar *>(bitArray.d.constData()),
                       size_t(qMax(0, m)), seed);

    // deal with the last 0 to 7 bits manually, because we can't trust that
    // the padding is initialized to 0 in bitArray.d
    int n = bitArray.size();
    if (n & 0x7)
        result = ((result << 4) + bitArray.d.at(m)) & ((1 << n) - 1);
    return result;
}

uint qHash(QLatin1String key, uint seed) noexcept
{
    return hash(reinterpret_cast<const uchar *>(key.data()), size_t(key.size()), seed);
}

/*!
    \internal

    Creates the QHash random seed from various sources.
    In order of decreasing precedence:
    - under Unix, it attemps to read from /dev/urandom;
    - under Unix, it attemps to read from /dev/random;
    - under Windows, it attempts to use rand_s;
    - as a general fallback, the application's PID, a timestamp and the
      address of a stack-local variable are used.
*/
static uint qt_create_qhash_seed()
{
    uint seed = 0;

#ifndef QT_BOOTSTRAPPED
    QByteArray envSeed = qgetenv("QT_HASH_SEED");
    if (!envSeed.isNull()) {
        uint seed = envSeed.toUInt();
        if (seed) {
            // can't use qWarning here (reentrancy)
            fprintf(stderr, "QT_HASH_SEED: forced seed value is not 0, cannot guarantee that the "
                     "hashing functions will produce a stable value.");
        }
        return seed;
    }

    seed = QRandomGenerator::system()->generate();
#endif // QT_BOOTSTRAPPED

    return seed;
}

/*
    The QHash seed itself.
*/
static QBasicAtomicInt qt_qhash_seed = Q_BASIC_ATOMIC_INITIALIZER(-1);

/*!
    \internal

    Seed == -1 means it that it was not initialized yet.

    We let qt_create_qhash_seed return any unsigned integer,
    but convert it to signed in order to initialize the seed.

    We don't actually care about the fact that different calls to
    qt_create_qhash_seed() might return different values,
    as long as in the end everyone uses the very same value.
*/
static void qt_initialize_qhash_seed()
{
    if (qt_qhash_seed.loadRelaxed() == -1) {
        int x(qt_create_qhash_seed() & INT_MAX);
        qt_qhash_seed.testAndSetRelaxed(-1, x);
    }
}

/*! \relates QHash
    \since 5.6

    Returns the current global QHash seed.

    The seed is set in any newly created QHash. See \l{qHash} about how this seed
    is being used by QHash.

    \sa qSetGlobalQHashSeed
 */
int qGlobalQHashSeed()
{
    qt_initialize_qhash_seed();
    return qt_qhash_seed.loadRelaxed();
}

/*! \relates QHash
    \since 5.6

    Sets the global QHash seed to \a newSeed.

    Manually setting the global QHash seed value should be done only for testing
    and debugging purposes, when deterministic and reproducible behavior on a QHash
    is needed. We discourage to do it in production code as it can make your
    application susceptible to \l{algorithmic complexity attacks}.

    From Qt 5.10 and onwards, the only allowed values are 0 and -1. Passing the
    value -1 will reinitialize the global QHash seed to a random value, while
    the value of 0 is used to request a stable algorithm for C++ primitive
    types types (like \c int) and string types (QString, QByteArray).

    The seed is set in any newly created QHash. See \l{qHash} about how this seed
    is being used by QHash.

    If the environment variable \c QT_HASH_SEED is set, calling this function will
    result in a no-op.

    \sa qGlobalQHashSeed
 */
void qSetGlobalQHashSeed(int newSeed)
{
    if (qEnvironmentVariableIsSet("QT_HASH_SEED"))
        return;
    if (newSeed == -1) {
        int x(qt_create_qhash_seed() & INT_MAX);
        qt_qhash_seed.storeRelaxed(x);
    } else {
        if (newSeed) {
            // can't use qWarning here (reentrancy)
            fprintf(stderr, "qSetGlobalQHashSeed: forced seed value is not 0, cannot guarantee that the "
                            "hashing functions will produce a stable value.");
        }
        qt_qhash_seed.storeRelaxed(newSeed & INT_MAX);
    }
}

/*!
    \internal

    Private copy of the implementation of the Qt 4 qHash algorithm for strings,
    (that is, QChar-based arrays, so all QString-like classes),
    to be used wherever the result is somehow stored or reused across multiple
    Qt versions. The public qHash implementation can change at any time,
    therefore one must not rely on the fact that it will always give the same
    results.

    The qt_hash functions must *never* change their results.

    This function can hash discontiguous memory by invoking it on each chunk,
    passing the previous's result in the next call's \a chained argument.
*/
uint qt_hash(QStringView key, uint chained) noexcept
{
    auto n = key.size();
    auto p = key.utf16();

    uint h = chained;

    while (n--) {
        h = (h << 4) + *p++;
        h ^= (h & 0xf0000000) >> 23;
        h &= 0x0fffffff;
    }
    return h;
}

/*
    The prime_deltas array contains the difference between a power
    of two and the next prime number:

    prime_deltas[i] = nextprime(2^i) - 2^i

    Basically, it's sequence A092131 from OEIS, assuming:
    - nextprime(1) = 1
    - nextprime(2) = 2
    and
    - left-extending it for the offset 0 (A092131 starts at i=1)
    - stopping the sequence at i = 28 (the table is big enough...)
*/

static const uchar prime_deltas[] = {
    0,  0,  1,  3,  1,  5,  3,  3,  1,  9,  7,  5,  3, 17, 27,  3,
    1, 29,  3, 21,  7, 17, 15,  9, 43, 35, 15,  0,  0,  0,  0,  0
};

/*
    The primeForNumBits() function returns the prime associated to a
    power of two. For example, primeForNumBits(8) returns 257.
*/

static inline int primeForNumBits(int numBits)
{
    return (1 << numBits) + prime_deltas[numBits];
}

/*
    Returns the smallest integer n such that
    primeForNumBits(n) >= hint.
*/
static int countBits(int hint)
{
    int numBits = 0;
    int bits = hint;

    while (bits > 1) {
        bits >>= 1;
        numBits++;
    }

    if (numBits >= (int)sizeof(prime_deltas)) {
        numBits = sizeof(prime_deltas) - 1;
    } else if (primeForNumBits(numBits) < hint) {
        ++numBits;
    }
    return numBits;
}

/*
    A QHash has initially around pow(2, MinNumBits) buckets. For
    example, if MinNumBits is 4, it has 17 buckets.
*/
const int MinNumBits = 4;

const QHashData QHashData::shared_null = {
    nullptr, nullptr, Q_REFCOUNT_INITIALIZE_STATIC, 0, 0, MinNumBits, 0, 0, 0, true, false, 0
};

void *QHashData::allocateNode(int nodeAlign)
{
    void *ptr = strictAlignment ? qMallocAligned(nodeSize, nodeAlign) : malloc(nodeSize);
    Q_CHECK_PTR(ptr);
    return ptr;
}

void QHashData::freeNode(void *node)
{
    if (strictAlignment)
        qFreeAligned(node);
    else
        free(node);
}

QHashData *QHashData::detach_helper(void (*node_duplicate)(Node *, void *),
                                    void (*node_delete)(Node *),
                                    int nodeSize,
                                    int nodeAlign)
{
    union {
        QHashData *d;
        Node *e;
    };
    if (this == &shared_null)
        qt_initialize_qhash_seed(); // may throw
    d = new QHashData;
    d->fakeNext = nullptr;
    d->buckets = nullptr;
    d->ref.initializeOwned();
    d->size = size;
    d->nodeSize = nodeSize;
    d->userNumBits = userNumBits;
    d->numBits = numBits;
    d->numBuckets = numBuckets;
    d->seed = (this == &shared_null) ? uint(qt_qhash_seed.loadRelaxed()) : seed;
    d->sharable = true;
    d->strictAlignment = nodeAlign > 8;
    d->reserved = 0;

    if (numBuckets) {
        QT_TRY {
            d->buckets = new Node *[numBuckets];
        } QT_CATCH(...) {
            // restore a consistent state for d
            d->numBuckets = 0;
            // roll back
            d->free_helper(node_delete);
            QT_RETHROW;
        }

        Node *this_e = reinterpret_cast<Node *>(this);
        for (int i = 0; i < numBuckets; ++i) {
            Node **nextNode = &d->buckets[i];
            Node *oldNode = buckets[i];
            while (oldNode != this_e) {
                QT_TRY {
                    Node *dup = static_cast<Node *>(allocateNode(nodeAlign));

                    QT_TRY {
                        node_duplicate(oldNode, dup);
                    } QT_CATCH(...) {
                        freeNode( dup );
                        QT_RETHROW;
                    }

                    *nextNode = dup;
                    nextNode = &dup->next;
                    oldNode = oldNode->next;
                } QT_CATCH(...) {
                    // restore a consistent state for d
                    *nextNode = e;
                    d->numBuckets = i+1;
                    // roll back
                    d->free_helper(node_delete);
                    QT_RETHROW;
                }
            }
            *nextNode = e;
        }
    }
    return d;
}

void QHashData::free_helper(void (*node_delete)(Node *))
{
    if (node_delete) {
        Node *this_e = reinterpret_cast<Node *>(this);
        Node **bucket = reinterpret_cast<Node **>(this->buckets);

        int n = numBuckets;
        while (n--) {
            Node *cur = *bucket++;
            while (cur != this_e) {
                Node *next = cur->next;
                node_delete(cur);
                freeNode(cur);
                cur = next;
            }
        }
    }
    delete [] buckets;
    delete this;
}

QHashData::Node *QHashData::nextNode(Node *node)
{
    union {
        Node *next;
        Node *e;
        QHashData *d;
    };
    next = node->next;
    Q_ASSERT_X(next, "QHash", "Iterating beyond end()");
    if (next->next)
        return next;

    int start = (node->h % d->numBuckets) + 1;
    Node **bucket = d->buckets + start;
    int n = d->numBuckets - start;
    while (n--) {
        if (*bucket != e)
            return *bucket;
        ++bucket;
    }
    return e;
}

QHashData::Node *QHashData::previousNode(Node *node)
{
    union {
        Node *e;
        QHashData *d;
    };

    e = node;
    while (e->next)
        e = e->next;

    int start;
    if (node == e)
        start = d->numBuckets - 1;
    else
        start = node->h % d->numBuckets;

    Node *sentinel = node;
    Node **bucket = d->buckets + start;
    while (start >= 0) {
        if (*bucket != sentinel) {
            Node *prev = *bucket;
            while (prev->next != sentinel)
                prev = prev->next;
            return prev;
        }

        sentinel = e;
        --bucket;
        --start;
    }
    Q_ASSERT_X(start >= 0, "QHash", "Iterating backward beyond begin()");
    return e;
}

/*
    If hint is negative, -hint gives the approximate number of
    buckets that should be used for the hash table. If hint is
    nonnegative, (1 << hint) gives the approximate number
    of buckets that should be used.
*/
void QHashData::rehash(int hint)
{
    if (hint < 0) {
        hint = countBits(-hint);
        if (hint < MinNumBits)
            hint = MinNumBits;
        userNumBits = hint;
        while (primeForNumBits(hint) < (size >> 1))
            ++hint;
    } else if (hint < MinNumBits) {
        hint = MinNumBits;
    }

    if (numBits != hint) {
        Node *e = reinterpret_cast<Node *>(this);
        Node **oldBuckets = buckets;
        int oldNumBuckets = numBuckets;

        int nb = primeForNumBits(hint);
        buckets = new Node *[nb];
        numBits = hint;
        numBuckets = nb;
        for (int i = 0; i < numBuckets; ++i)
            buckets[i] = e;

        for (int i = 0; i < oldNumBuckets; ++i) {
            Node *firstNode = oldBuckets[i];
            while (firstNode != e) {
                uint h = firstNode->h;
                Node *lastNode = firstNode;
                while (lastNode->next != e && lastNode->next->h == h)
                    lastNode = lastNode->next;

                Node *afterLastNode = lastNode->next;
                Node **beforeFirstNode = &buckets[h % numBuckets];
                while (*beforeFirstNode != e)
                    beforeFirstNode = &(*beforeFirstNode)->next;
                lastNode->next = *beforeFirstNode;
                *beforeFirstNode = firstNode;
                firstNode = afterLastNode;
            }
        }
        delete [] oldBuckets;
    }
}

#ifdef QT_QHASH_DEBUG

void QHashData::dump()
{
    qDebug("Hash data (ref = %d, size = %d, nodeSize = %d, userNumBits = %d, numBits = %d, numBuckets = %d)",
            int(ref), size, nodeSize, userNumBits, numBits,
            numBuckets);
    qDebug("    %p (fakeNode = %p)", this, fakeNext);
    for (int i = 0; i < numBuckets; ++i) {
        Node *n = buckets[i];
        if (n != reinterpret_cast<Node *>(this)) {
            QString line = QString::asprintf("%d:", i);
            while (n != reinterpret_cast<Node *>(this)) {
                line += QString::asprintf(" -> [%p]", n);
                if (!n) {
                    line += " (CORRUPT)";
                    break;
                }
                n = n->next;
            }
            qDebug("%ls", qUtf16Printable(line));
        }
    }
}

void QHashData::checkSanity()
{
    if (Q_UNLIKELY(fakeNext))
        qFatal("Fake next isn't 0");

    for (int i = 0; i < numBuckets; ++i) {
        Node *n = buckets[i];
        Node *p = n;
        if (Q_UNLIKELY(!n))
            qFatal("%d: Bucket entry is 0", i);
        if (n != reinterpret_cast<Node *>(this)) {
            while (n != reinterpret_cast<Node *>(this)) {
                if (Q_UNLIKELY(!n->next))
                    qFatal("%d: Next of %p is 0, should be %p", i, n, this);
                n = n->next;
            }
        }
    }
}
#endif

/*!
    \fn template <typename T1, typename T2> uint qHash(const QPair<T1, T2> &key, uint seed = 0)
    \since 5.0
    \relates QHash

    Returns the hash value for the \a key, using \a seed to seed the calculation.

    Types \c T1 and \c T2 must be supported by qHash().
*/

/*!
    \fn template <typename T1, typename T2> uint qHash(const std::pair<T1, T2> &key, uint seed = 0)
    \since 5.7
    \relates QHash

    Returns the hash value for the \a key, using \a seed to seed the calculation.

    Types \c T1 and \c T2 must be supported by qHash().

    \note The return type of this function is \e{not} the same as that of
    \snippet code/src_corelib_tools_qhash.cpp 29
    The two functions use different hashing algorithms; due to binary compatibility
    constraints, we cannot change the QPair algorithm to match the std::pair one before Qt 6.
*/

/*! \fn template <typename InputIterator> uint qHashRange(InputIterator first, InputIterator last, uint seed = 0)
    \relates QHash
    \since 5.5

    Returns the hash value for the range [\a{first},\a{last}), using \a seed
    to seed the calculation, by successively applying qHash() to each
    element and combining the hash values into a single one.

    The return value of this function depends on the order of elements
    in the range. That means that

    \snippet code/src_corelib_tools_qhash.cpp 30

    and
    \snippet code/src_corelib_tools_qhash.cpp 31

    hash to \b{different} values. If order does not matter, for example for hash
    tables, use qHashRangeCommutative() instead. If you are hashing raw
    memory, use qHashBits().

    Use this function only to implement qHash() for your own custom
    types. For example, here's how you could implement a qHash() overload for
    std::vector<int>:

    \snippet code/src_corelib_tools_qhash.cpp qhashrange

    It bears repeating that the implementation of qHashRange() - like
    the qHash() overloads offered by Qt - may change at any time. You
    \b{must not} rely on the fact that qHashRange() will give the same
    results (for the same inputs) across different Qt versions, even
    if qHash() for the element type would.

    \sa qHashBits(), qHashRangeCommutative()
*/

/*! \fn template <typename InputIterator> uint qHashRangeCommutative(InputIterator first, InputIterator last, uint seed = 0)
    \relates QHash
    \since 5.5

    Returns the hash value for the range [\a{first},\a{last}), using \a seed
    to seed the calculation, by successively applying qHash() to each
    element and combining the hash values into a single one.

    The return value of this function does not depend on the order of
    elements in the range. That means that

    \snippet code/src_corelib_tools_qhash.cpp 30

    and
    \snippet code/src_corelib_tools_qhash.cpp 31

    hash to the \b{same} values. If order matters, for example, for vectors
    and arrays, use qHashRange() instead. If you are hashing raw
    memory, use qHashBits().

    Use this function only to implement qHash() for your own custom
    types. For example, here's how you could implement a qHash() overload for
    std::unordered_set<int>:

    \snippet code/src_corelib_tools_qhash.cpp qhashrangecommutative

    It bears repeating that the implementation of
    qHashRangeCommutative() - like the qHash() overloads offered by Qt
    - may change at any time. You \b{must not} rely on the fact that
    qHashRangeCommutative() will give the same results (for the same
    inputs) across different Qt versions, even if qHash() for the
    element type would.

    \sa qHashBits(), qHashRange()
*/

/*! \fn uint qHashBits(const void *p, size_t len, uint seed = 0)
    \relates QHash
    \since 5.4

    Returns the hash value for the memory block of size \a len pointed
    to by \a p, using \a seed to seed the calculation.

    Use this function only to implement qHash() for your own custom
    types. For example, here's how you could implement a qHash() overload for
    std::vector<int>:

    \snippet code/src_corelib_tools_qhash.cpp qhashbits

    This takes advantage of the fact that std::vector lays out its data
    contiguously. If that is not the case, or the contained type has
    padding, you should use qHashRange() instead.

    It bears repeating that the implementation of qHashBits() - like
    the qHash() overloads offered by Qt - may change at any time. You
    \b{must not} rely on the fact that qHashBits() will give the same
    results (for the same inputs) across different Qt versions.

    \sa qHashRange(), qHashRangeCommutative()
*/

/*! \fn uint qHash(char key, uint seed = 0)
    \relates QHash
    \since 5.0

    Returns the hash value for the \a key, using \a seed to seed the calculation.
*/

/*! \fn uint qHash(uchar key, uint seed = 0)
    \relates QHash
    \since 5.0

    Returns the hash value for the \a key, using \a seed to seed the calculation.
*/

/*! \fn uint qHash(signed char key, uint seed = 0)
    \relates QHash
    \since 5.0

    Returns the hash value for the \a key, using \a seed to seed the calculation.
*/

/*! \fn uint qHash(ushort key, uint seed = 0)
    \relates QHash
    \since 5.0

    Returns the hash value for the \a key, using \a seed to seed the calculation.
*/

/*! \fn uint qHash(short key, uint seed = 0)
    \relates QHash
    \since 5.0

    Returns the hash value for the \a key, using \a seed to seed the calculation.
*/

/*! \fn uint qHash(uint key, uint seed = 0)
    \relates QHash
    \since 5.0

    Returns the hash value for the \a key, using \a seed to seed the calculation.
*/

/*! \fn uint qHash(int key, uint seed = 0)
    \relates QHash
    \since 5.0

    Returns the hash value for the \a key, using \a seed to seed the calculation.
*/

/*! \fn uint qHash(ulong key, uint seed = 0)
    \relates QHash
    \since 5.0

    Returns the hash value for the \a key, using \a seed to seed the calculation.
*/

/*! \fn uint qHash(long key, uint seed = 0)
    \relates QHash
    \since 5.0

    Returns the hash value for the \a key, using \a seed to seed the calculation.
*/

/*! \fn uint qHash(quint64 key, uint seed = 0)
    \relates QHash
    \since 5.0

    Returns the hash value for the \a key, using \a seed to seed the calculation.
*/

/*! \fn uint qHash(qint64 key, uint seed = 0)
    \relates QHash
    \since 5.0

    Returns the hash value for the \a key, using \a seed to seed the calculation.
*/

/*! \relates QHash
    \since 5.3

    Returns the hash value for the \a key, using \a seed to seed the calculation.
*/
uint qHash(float key, uint seed) noexcept
{
    return key != 0.0f ? hash(reinterpret_cast<const uchar *>(&key), sizeof(key), seed) : seed ;
}

/*! \relates QHash
    \since 5.3

    Returns the hash value for the \a key, using \a seed to seed the calculation.
*/
uint qHash(double key, uint seed) noexcept
{
    return key != 0.0  ? hash(reinterpret_cast<const uchar *>(&key), sizeof(key), seed) : seed ;
}

#if !defined(Q_OS_DARWIN) || defined(Q_CLANG_QDOC)
/*! \relates QHash
    \since 5.3

    Returns the hash value for the \a key, using \a seed to seed the calculation.
*/
uint qHash(long double key, uint seed) noexcept
{
    return key != 0.0L ? hash(reinterpret_cast<const uchar *>(&key), sizeof(key), seed) : seed ;
}
#endif

/*! \fn uint qHash(const QChar key, uint seed = 0)
    \relates QHash
    \since 5.0

    Returns the hash value for the \a key, using \a seed to seed the calculation.
*/

/*! \fn uint qHash(const QByteArray &key, uint seed = 0)
    \relates QHash
    \since 5.0

    Returns the hash value for the \a key, using \a seed to seed the calculation.
*/

/*! \fn uint qHash(const QBitArray &key, uint seed = 0)
    \relates QHash
    \since 5.0

    Returns the hash value for the \a key, using \a seed to seed the calculation.
*/

/*! \fn uint qHash(const QString &key, uint seed = 0)
    \relates QHash
    \since 5.0

    Returns the hash value for the \a key, using \a seed to seed the calculation.
*/

/*! \fn uint qHash(const QStringRef &key, uint seed = 0)
    \relates QHash
    \since 5.0

    Returns the hash value for the \a key, using \a seed to seed the calculation.
*/

/*! \fn uint qHash(QStringView key, uint seed = 0)
    \relates QStringView
    \since 5.10

    Returns the hash value for the \a key, using \a seed to seed the calculation.
*/

/*! \fn uint qHash(QLatin1String key, uint seed = 0)
    \relates QHash
    \since 5.0

    Returns the hash value for the \a key, using \a seed to seed the calculation.
*/

/*! \fn template <class T> uint qHash(const T *key, uint seed = 0)
    \relates QHash
    \since 5.0

    Returns the hash value for the \a key, using \a seed to seed the calculation.
*/

/*!
    \class QHash
    \inmodule QtCore
    \brief The QHash class is a template class that provides a hash-table-based dictionary.

    \ingroup tools
    \ingroup shared

    \reentrant

    QHash\<Key, T\> is one of Qt's generic \l{container classes}. It
    stores (key, value) pairs and provides very fast lookup of the
    value associated with a key.

    QHash provides very similar functionality to QMap. The
    differences are:

    \list
    \li QHash provides faster lookups than QMap. (See \l{Algorithmic
       Complexity} for details.)
    \li When iterating over a QMap, the items are always sorted by
       key. With QHash, the items are arbitrarily ordered.
    \li The key type of a QMap must provide operator<(). The key
       type of a QHash must provide operator==() and a global
       hash function called qHash() (see \l{qHash}).
    \endlist

    Here's an example QHash with QString keys and \c int values:
    \snippet code/src_corelib_tools_qhash.cpp 0

    To insert a (key, value) pair into the hash, you can use operator[]():

    \snippet code/src_corelib_tools_qhash.cpp 1

    This inserts the following three (key, value) pairs into the
    QHash: ("one", 1), ("three", 3), and ("seven", 7). Another way to
    insert items into the hash is to use insert():

    \snippet code/src_corelib_tools_qhash.cpp 2

    To look up a value, use operator[]() or value():

    \snippet code/src_corelib_tools_qhash.cpp 3

    If there is no item with the specified key in the hash, these
    functions return a \l{default-constructed value}.

    If you want to check whether the hash contains a particular key,
    use contains():

    \snippet code/src_corelib_tools_qhash.cpp 4

    There is also a value() overload that uses its second argument as
    a default value if there is no item with the specified key:

    \snippet code/src_corelib_tools_qhash.cpp 5

    In general, we recommend that you use contains() and value()
    rather than operator[]() for looking up a key in a hash. The
    reason is that operator[]() silently inserts an item into the
    hash if no item exists with the same key (unless the hash is
    const). For example, the following code snippet will create 1000
    items in memory:

    \snippet code/src_corelib_tools_qhash.cpp 6

    To avoid this problem, replace \c hash[i] with \c hash.value(i)
    in the code above.

    Internally, QHash uses a hash table to perform lookups. This
    hash table automatically grows and shrinks to
    provide fast lookups without wasting too much memory. You can
    still control the size of the hash table by calling reserve() if
    you already know approximately how many items the QHash will
    contain, but this isn't necessary to obtain good performance. You
    can also call capacity() to retrieve the hash table's size.

    If you want to navigate through all the (key, value) pairs stored
    in a QHash, you can use an iterator. QHash provides both
    \l{Java-style iterators} (QHashIterator and QMutableHashIterator)
    and \l{STL-style iterators} (QHash::const_iterator and
    QHash::iterator). Here's how to iterate over a QHash<QString,
    int> using a Java-style iterator:

    \snippet code/src_corelib_tools_qhash.cpp 7

    Here's the same code, but using an STL-style iterator:

    \snippet code/src_corelib_tools_qhash.cpp 8

    QHash is unordered, so an iterator's sequence cannot be assumed
    to be predictable. If ordering by key is required, use a QMap.

    Normally, a QHash allows only one value per key. If you call
    insert() with a key that already exists in the QHash, the
    previous value is erased. For example:

    \snippet code/src_corelib_tools_qhash.cpp 9

    If you only need to extract the values from a hash (not the keys),
    you can also use \l{foreach}:

    \snippet code/src_corelib_tools_qhash.cpp 12

    Items can be removed from the hash in several ways. One way is to
    call remove(); this will remove any item with the given key.
    Another way is to use QMutableHashIterator::remove(). In addition,
    you can clear the entire hash using clear().

    QHash's key and value data types must be \l{assignable data
    types}. You cannot, for example, store a QWidget as a value;
    instead, store a QWidget *.

    \target qHash
    \section2 The qHash() hashing function

    A QHash's key type has additional requirements other than being an
    assignable data type: it must provide operator==(), and there must also be
    a qHash() function in the type's namespace that returns a hash value for an
    argument of the key's type.

    The qHash() function computes a numeric value based on a key. It
    can use any algorithm imaginable, as long as it always returns
    the same value if given the same argument. In other words, if
    \c{e1 == e2}, then \c{qHash(e1) == qHash(e2)} must hold as well.
    However, to obtain good performance, the qHash() function should
    attempt to return different hash values for different keys to the
    largest extent possible.

    For a key type \c{K}, the qHash function must have one of these signatures:

    \snippet code/src_corelib_tools_qhash.cpp 32

    The two-arguments overloads take an unsigned integer that should be used to
    seed the calculation of the hash function. This seed is provided by QHash
    in order to prevent a family of \l{algorithmic complexity attacks}. If both
    a one-argument and a two-arguments overload are defined for a key type,
    the latter is used by QHash (note that you can simply define a
    two-arguments version, and use a default value for the seed parameter).

    Here's a partial list of the C++ and Qt types that can serve as keys in a
    QHash: any integer type (char, unsigned long, etc.), any pointer type,
    QChar, QString, and QByteArray. For all of these, the \c <QHash> header
    defines a qHash() function that computes an adequate hash value. Many other
    Qt classes also declare a qHash overload for their type; please refer to
    the documentation of each class.

    If you want to use other types as the key, make sure that you provide
    operator==() and a qHash() implementation.

    Example:
    \snippet code/src_corelib_tools_qhash.cpp 13

    In the example above, we've relied on Qt's global qHash(const
    QString &, uint) to give us a hash value for the employee's name, and
    XOR'ed this with the day they were born to help produce unique
    hashes for people with the same name.

    Note that the implementation of the qHash() overloads offered by Qt
    may change at any time. You \b{must not} rely on the fact that qHash()
    will give the same results (for the same inputs) across different Qt
    versions.

    \section2 Algorithmic complexity attacks

    All hash tables are vulnerable to a particular class of denial of service
    attacks, in which the attacker carefully pre-computes a set of different
    keys that are going to be hashed in the same bucket of a hash table (or
    even have the very same hash value). The attack aims at getting the
    worst-case algorithmic behavior (O(n) instead of amortized O(1), see
    \l{Algorithmic Complexity} for the details) when the data is fed into the
    table.

    In order to avoid this worst-case behavior, the calculation of the hash
    value done by qHash() can be salted by a random seed, that nullifies the
    attack's extent. This seed is automatically generated by QHash once per
    process, and then passed by QHash as the second argument of the
    two-arguments overload of the qHash() function.

    This randomization of QHash is enabled by default. Even though programs
    should never depend on a particular QHash ordering, there may be situations
    where you temporarily need deterministic behavior, for example for debugging or
    regression testing. To disable the randomization, define the environment
    variable \c QT_HASH_SEED to have the value 0. Alternatively, you can call
    the qSetGlobalQHashSeed() function with the value 0.

    \sa QHashIterator, QMutableHashIterator, QMap, QSet
*/

/*! \fn template <class Key, class T> QHash<Key, T>::QHash()

    Constructs an empty hash.

    \sa clear()
*/

/*!
    \fn template <class Key, class T> QHash<Key, T>::QHash(QHash &&other)

    Move-constructs a QHash instance, making it point at the same
    object that \a other was pointing to.

    \since 5.2
*/

/*! \fn template <class Key, class T> QHash<Key, T>::QHash(std::initializer_list<std::pair<Key,T> > list)
    \since 5.1

    Constructs a hash with a copy of each of the elements in the
    initializer list \a list.

    This function is only available if the program is being
    compiled in C++11 mode.
*/

/*! \fn template <class Key, class T> template <class InputIterator> QHash<Key, T>::QHash(InputIterator begin, InputIterator end)
    \since 5.14

    Constructs a hash with a copy of each of the elements in the iterator range
    [\a begin, \a end). Either the elements iterated by the range must be
    objects with \c{first} and \c{second} data members (like \c{QPair},
    \c{std::pair}, etc.) convertible to \c Key and to \c T respectively; or the
    iterators must have \c{key()} and \c{value()} member functions, returning a
    key convertible to \c Key and a value convertible to \c T respectively.
*/

/*! \fn template <class Key, class T> QHash<Key, T>::QHash(const QHash &other)

    Constructs a copy of \a other.

    This operation occurs in \l{constant time}, because QHash is
    \l{implicitly shared}. This makes returning a QHash from a
    function very fast. If a shared instance is modified, it will be
    copied (copy-on-write), and this takes \l{linear time}.

    \sa operator=()
*/

/*! \fn template <class Key, class T> QHash<Key, T>::~QHash()

    Destroys the hash. References to the values in the hash and all
    iterators of this hash become invalid.
*/

/*! \fn template <class Key, class T> QHash &QHash<Key, T>::operator=(const QHash &other)

    Assigns \a other to this hash and returns a reference to this hash.
*/

/*!
    \fn template <class Key, class T> QHash &QHash<Key, T>::operator=(QHash &&other)

    Move-assigns \a other to this QHash instance.

    \since 5.2
*/

/*! \fn template <class Key, class T> void QHash<Key, T>::swap(QHash &other)
    \since 4.8

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

/*! \fn template <class Key, class T> void QMultiHash<Key, T>::swap(QMultiHash &other)
    \since 4.8

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

/*! \fn template <class Key, class T> bool QHash<Key, T>::operator==(const QHash &other) const

    Returns \c true if \a other is equal to this hash; otherwise returns
    false.

    Two hashes are considered equal if they contain the same (key,
    value) pairs.

    This function requires the value type to implement \c operator==().

    \sa operator!=()
*/

/*! \fn template <class Key, class T> bool QHash<Key, T>::operator!=(const QHash &other) const

    Returns \c true if \a other is not equal to this hash; otherwise
    returns \c false.

    Two hashes are considered equal if they contain the same (key,
    value) pairs.

    This function requires the value type to implement \c operator==().

    \sa operator==()
*/

/*! \fn template <class Key, class T> int QHash<Key, T>::size() const

    Returns the number of items in the hash.

    \sa isEmpty(), count()
*/

/*! \fn template <class Key, class T> bool QHash<Key, T>::isEmpty() const

    Returns \c true if the hash contains no items; otherwise returns
    false.

    \sa size()
*/

/*! \fn template <class Key, class T> int QHash<Key, T>::capacity() const

    Returns the number of buckets in the QHash's internal hash table.

    The sole purpose of this function is to provide a means of fine
    tuning QHash's memory usage. In general, you will rarely ever
    need to call this function. If you want to know how many items are
    in the hash, call size().

    \sa reserve(), squeeze()
*/

/*! \fn template <class Key, class T> void QHash<Key, T>::reserve(int size)

    Ensures that the QHash's internal hash table consists of at least
    \a size buckets.

    This function is useful for code that needs to build a huge hash
    and wants to avoid repeated reallocation. For example:

    \snippet code/src_corelib_tools_qhash.cpp 14

    Ideally, \a size should be slightly more than the maximum number
    of items expected in the hash. \a size doesn't have to be prime,
    because QHash will use a prime number internally anyway. If \a size
    is an underestimate, the worst that will happen is that the QHash
    will be a bit slower.

    In general, you will rarely ever need to call this function.
    QHash's internal hash table automatically shrinks or grows to
    provide good performance without wasting too much memory.

    \sa squeeze(), capacity()
*/

/*! \fn template <class Key, class T> void QHash<Key, T>::squeeze()

    Reduces the size of the QHash's internal hash table to save
    memory.

    The sole purpose of this function is to provide a means of fine
    tuning QHash's memory usage. In general, you will rarely ever
    need to call this function.

    \sa reserve(), capacity()
*/

/*! \fn template <class Key, class T> void QHash<Key, T>::detach()

    \internal

    Detaches this hash from any other hashes with which it may share
    data.

    \sa isDetached()
*/

/*! \fn template <class Key, class T> bool QHash<Key, T>::isDetached() const

    \internal

    Returns \c true if the hash's internal data isn't shared with any
    other hash object; otherwise returns \c false.

    \sa detach()
*/

/*! \fn template <class Key, class T> void QHash<Key, T>::setSharable(bool sharable)

    \internal
*/

/*! \fn template <class Key, class T> bool QHash<Key, T>::isSharedWith(const QHash &other) const

    \internal
*/

/*! \fn template <class Key, class T> void QHash<Key, T>::clear()

    Removes all items from the hash.

    \sa remove()
*/

/*! \fn template <class Key, class T> int QHash<Key, T>::remove(const Key &key)

    Removes all the items that have the \a key from the hash.
    Returns the number of items removed which is 1 if the key exists in the hash,
    and 0 otherwise.

    \sa clear(), take(), QMultiHash::remove()
*/

/*! \fn template <class Key, class T> T QHash<Key, T>::take(const Key &key)

    Removes the item with the \a key from the hash and returns
    the value associated with it.

    If the item does not exist in the hash, the function simply
    returns a \l{default-constructed value}. If there are multiple
    items for \a key in the hash, only the most recently inserted one
    is removed.

    If you don't use the return value, remove() is more efficient.

    \sa remove()
*/

/*! \fn template <class Key, class T> bool QHash<Key, T>::contains(const Key &key) const

    Returns \c true if the hash contains an item with the \a key;
    otherwise returns \c false.

    \sa count(), QMultiHash::contains()
*/

/*! \fn template <class Key, class T> const T QHash<Key, T>::value(const Key &key) const

    Returns the value associated with the \a key.

    If the hash contains no item with the \a key, the function
    returns a \l{default-constructed value}. If there are multiple
    items for the \a key in the hash, the value of the most recently
    inserted one is returned.

    \sa key(), values(), contains(), operator[]()
*/

/*! \fn template <class Key, class T> const T QHash<Key, T>::value(const Key &key, const T &defaultValue) const
    \overload

    If the hash contains no item with the given \a key, the function returns
    \a defaultValue.
*/

/*! \fn template <class Key, class T> T &QHash<Key, T>::operator[](const Key &key)

    Returns the value associated with the \a key as a modifiable
    reference.

    If the hash contains no item with the \a key, the function inserts
    a \l{default-constructed value} into the hash with the \a key, and
    returns a reference to it. If the hash contains multiple items
    with the \a key, this function returns a reference to the most
    recently inserted value.

    \sa insert(), value()
*/

/*! \fn template <class Key, class T> const T QHash<Key, T>::operator[](const Key &key) const

    \overload

    Same as value().
*/

/*! \fn template <class Key, class T> QList<Key> QHash<Key, T>::uniqueKeys() const
    \since 4.2
    \obsolete

    Returns a list containing all the keys in the map. Keys that occur multiple
    times in the map (because items were inserted with insertMulti(), or
    unite() was used) occur only once in the returned list.

    \sa QMultiHash::uniqueKeys()
*/

/*! \fn template <class Key, class T> QList<Key> QHash<Key, T>::keys() const

    Returns a list containing all the keys in the hash, in an
    arbitrary order. Keys that occur multiple times in the hash
    (because the method is operating on a QMultiHash) also occur
    multiple times in the list.

    The order is guaranteed to be the same as that used by values().

    \sa QMultiMap::uniqueKeys(), values(), key()
*/

/*! \fn template <class Key, class T> QList<Key> QHash<Key, T>::keys(const T &value) const

    \overload

    Returns a list containing all the keys associated with value \a
    value, in an arbitrary order.

    This function can be slow (\l{linear time}), because QHash's
    internal data structure is optimized for fast lookup by key, not
    by value.
*/

/*! \fn template <class Key, class T> QList<T> QHash<Key, T>::values() const

    Returns a list containing all the values in the hash, in an
    arbitrary order. If a key is associated with multiple values, all of
    its values will be in the list, and not just the most recently
    inserted one.

    The order is guaranteed to be the same as that used by keys().

    \sa keys(), value()
*/

/*! \fn template <class Key, class T> QList<T> QHash<Key, T>::values(const Key &key) const
    \obsolete
    \overload

    Returns a list of all the values associated with the \a key,
    from the most recently inserted to the least recently inserted.

    \sa count(), insertMulti()
*/

/*! \fn template <class Key, class T> Key QHash<Key, T>::key(const T &value) const

    Returns the first key mapped to \a value.

    If the hash contains no item with the \a value, the function
    returns a \l{default-constructed value}{default-constructed key}.

    This function can be slow (\l{linear time}), because QHash's
    internal data structure is optimized for fast lookup by key, not
    by value.

    \sa value(), keys()
*/

/*!
    \fn template <class Key, class T> Key QHash<Key, T>::key(const T &value, const Key &defaultKey) const
    \since 4.3
    \overload

    Returns the first key mapped to \a value, or \a defaultKey if the
    hash contains no item mapped to \a value.

    This function can be slow (\l{linear time}), because QHash's
    internal data structure is optimized for fast lookup by key, not
    by value.
*/

/*! \fn template <class Key, class T> int QHash<Key, T>::count(const Key &key) const
    \obsolete

    Returns the number of items associated with the \a key.

    \sa contains(), insertMulti()
*/

/*! \fn template <class Key, class T> int QHash<Key, T>::count() const

    \overload

    Same as size().
*/

/*! \fn template <class Key, class T> QHash<Key, T>::iterator QHash<Key, T>::begin()

    Returns an \l{STL-style iterators}{STL-style iterator} pointing to the first item in
    the hash.

    \sa constBegin(), end()
*/

/*! \fn template <class Key, class T> QHash<Key, T>::const_iterator QHash<Key, T>::begin() const

    \overload
*/

/*! \fn template <class Key, class T> QHash<Key, T>::const_iterator QHash<Key, T>::cbegin() const
    \since 5.0

    Returns a const \l{STL-style iterators}{STL-style iterator} pointing to the first item
    in the hash.

    \sa begin(), cend()
*/

/*! \fn template <class Key, class T> QHash<Key, T>::const_iterator QHash<Key, T>::constBegin() const

    Returns a const \l{STL-style iterators}{STL-style iterator} pointing to the first item
    in the hash.

    \sa begin(), constEnd()
*/

/*! \fn template <class Key, class T> QHash<Key, T>::key_iterator QHash<Key, T>::keyBegin() const
    \since 5.6

    Returns a const \l{STL-style iterators}{STL-style iterator} pointing to the first key
    in the hash.

    \sa keyEnd()
*/

/*! \fn template <class Key, class T> QHash<Key, T>::iterator QHash<Key, T>::end()

    Returns an \l{STL-style iterators}{STL-style iterator} pointing to the imaginary item
    after the last item in the hash.

    \sa begin(), constEnd()
*/

/*! \fn template <class Key, class T> QHash<Key, T>::const_iterator QHash<Key, T>::end() const

    \overload
*/

/*! \fn template <class Key, class T> QHash<Key, T>::const_iterator QHash<Key, T>::constEnd() const

    Returns a const \l{STL-style iterators}{STL-style iterator} pointing to the imaginary
    item after the last item in the hash.

    \sa constBegin(), end()
*/

/*! \fn template <class Key, class T> QHash<Key, T>::const_iterator QHash<Key, T>::cend() const
    \since 5.0

    Returns a const \l{STL-style iterators}{STL-style iterator} pointing to the imaginary
    item after the last item in the hash.

    \sa cbegin(), end()
*/

/*! \fn template <class Key, class T> QHash<Key, T>::key_iterator QHash<Key, T>::keyEnd() const
    \since 5.6

    Returns a const \l{STL-style iterators}{STL-style iterator} pointing to the imaginary
    item after the last key in the hash.

    \sa keyBegin()
*/

/*! \fn template <class Key, class T> QHash<Key, T>::key_value_iterator QHash<Key, T>::keyValueBegin()
    \since 5.10

    Returns an \l{STL-style iterators}{STL-style iterator} pointing to the first entry
    in the hash.

    \sa keyValueEnd()
*/

/*! \fn template <class Key, class T> QHash<Key, T>::key_value_iterator QHash<Key, T>::keyValueEnd()
    \since 5.10

    Returns an \l{STL-style iterators}{STL-style iterator} pointing to the imaginary
    entry after the last entry in the hash.

    \sa keyValueBegin()
*/

/*! \fn template <class Key, class T> QHash<Key, T>::const_key_value_iterator QHash<Key, T>::keyValueBegin() const
    \since 5.10

    Returns a const \l{STL-style iterators}{STL-style iterator} pointing to the first entry
    in the hash.

    \sa keyValueEnd()
*/

/*! \fn template <class Key, class T> QHash<Key, T>::const_key_value_iterator QHash<Key, T>::constKeyValueBegin() const
    \since 5.10

    Returns a const \l{STL-style iterators}{STL-style iterator} pointing to the first entry
    in the hash.

    \sa keyValueBegin()
*/

/*! \fn template <class Key, class T> QHash<Key, T>::const_key_value_iterator QHash<Key, T>::keyValueEnd() const
    \since 5.10

    Returns a const \l{STL-style iterators}{STL-style iterator} pointing to the imaginary
    entry after the last entry in the hash.

    \sa keyValueBegin()
*/

/*! \fn template <class Key, class T> QHash<Key, T>::const_key_value_iterator QHash<Key, T>::constKeyValueEnd() const
    \since 5.10

    Returns a const \l{STL-style iterators}{STL-style iterator} pointing to the imaginary
    entry after the last entry in the hash.

    \sa constKeyValueBegin()
*/

/*! \fn template <class Key, class T> QHash<Key, T>::iterator QHash<Key, T>::erase(const_iterator pos)
    \since 5.7

    Removes the (key, value) pair associated with the iterator \a pos
    from the hash, and returns an iterator to the next item in the
    hash.

    Unlike remove() and take(), this function never causes QHash to
    rehash its internal data structure. This means that it can safely
    be called while iterating, and won't affect the order of items in
    the hash. For example:

    \snippet code/src_corelib_tools_qhash.cpp 15

    \sa remove(), take(), find()
*/

/*! \fn template <class Key, class T> QHash<Key, T>::iterator QHash<Key, T>::erase(iterator pos)
    \overload
*/

/*! \fn template <class Key, class T> QHash<Key, T>::iterator QHash<Key, T>::find(const Key &key)

    Returns an iterator pointing to the item with the \a key in the
    hash.

    If the hash contains no item with the \a key, the function
    returns end().

    If the hash contains multiple items with the \a key, this
    function returns an iterator that points to the most recently
    inserted value. The other values are accessible by incrementing
    the iterator. For example, here's some code that iterates over all
    the items with the same key:

    \snippet code/src_corelib_tools_qhash.cpp 16

    \sa value(), values(), QMultiHash::find()
*/

/*! \fn template <class Key, class T> QHash<Key, T>::const_iterator QHash<Key, T>::find(const Key &key) const

    \overload
*/

/*! \fn template <class Key, class T> QHash<Key, T>::const_iterator QHash<Key, T>::constFind(const Key &key) const
    \since 4.1

    Returns an iterator pointing to the item with the \a key in the
    hash.

    If the hash contains no item with the \a key, the function
    returns constEnd().

    \sa find(), QMultiHash::constFind()
*/

/*! \fn template <class Key, class T> QHash<Key, T>::iterator QHash<Key, T>::insert(const Key &key, const T &value)

    Inserts a new item with the \a key and a value of \a value.

    If there is already an item with the \a key, that item's value
    is replaced with \a value.

    If there are multiple items with the \a key, the most
    recently inserted item's value is replaced with \a value.
*/

/*! \fn template <class Key, class T> void QHash<Key, T>::insert(const QHash &other)
    \since 5.15

    Inserts all the items in the \a other hash into this hash.

    If a key is common to both hashes, its value will be replaced with the
    value stored in \a other.

    \note If \a other contains multiple entries with the same key then the
    final value of the key is undefined.
*/

/*! \fn template <class Key, class T> QHash<Key, T>::iterator QHash<Key, T>::insertMulti(const Key &key, const T &value)
    \obsolete

    Inserts a new item with the \a key and a value of \a value.

    If there is already an item with the same key in the hash, this
    function will simply create a new one. (This behavior is
    different from insert(), which overwrites the value of an
    existing item.)

    This function is obsolete. Use QMultiHash or QMultiMap instead.

    \sa insert(), values()
*/

/*! \fn template <class Key, class T> QHash &QHash<Key, T>::unite(const QHash &other)
    \obsolete

    Inserts all the items in the \a other hash into this hash. If a
    key is common to both hashes, the resulting hash will contain the
    key multiple times.
*/

/*! \fn template <class Key, class T> bool QHash<Key, T>::empty() const

    This function is provided for STL compatibility. It is equivalent
    to isEmpty(), returning true if the hash is empty; otherwise
    returns \c false.
*/

/*! \fn template <class Key, class T> QPair<iterator, iterator> QHash<Key, T>::equal_range(const Key &key)
    \since 5.7

    Returns a pair of iterators delimiting the range of values \c{[first, second)}, that
    are stored under \a key. If the range is empty then both iterators will be equal to end().
*/

/*!
    \fn template <class Key, class T> QPair<const_iterator, const_iterator> QHash<Key, T>::equal_range(const Key &key) const
    \overload
    \since 5.7
*/

/*! \typedef QHash::ConstIterator

    Qt-style synonym for QHash::const_iterator.
*/

/*! \typedef QHash::Iterator

    Qt-style synonym for QHash::iterator.
*/

/*! \typedef QHash::difference_type

    Typedef for ptrdiff_t. Provided for STL compatibility.
*/

/*! \typedef QHash::key_type

    Typedef for Key. Provided for STL compatibility.
*/

/*! \typedef QHash::mapped_type

    Typedef for T. Provided for STL compatibility.
*/

/*! \typedef QHash::size_type

    Typedef for int. Provided for STL compatibility.
*/

/*! \typedef QHash::iterator::difference_type
    \internal
*/

/*! \typedef QHash::iterator::iterator_category
    \internal
*/

/*! \typedef QHash::iterator::pointer
    \internal
*/

/*! \typedef QHash::iterator::reference
    \internal
*/

/*! \typedef QHash::iterator::value_type
    \internal
*/

/*! \typedef QHash::const_iterator::difference_type
    \internal
*/

/*! \typedef QHash::const_iterator::iterator_category
    \internal
*/

/*! \typedef QHash::const_iterator::pointer
    \internal
*/

/*! \typedef QHash::const_iterator::reference
    \internal
*/

/*! \typedef QHash::const_iterator::value_type
    \internal
*/

/*! \typedef QHash::key_iterator::difference_type
    \internal
*/

/*! \typedef QHash::key_iterator::iterator_category
    \internal
*/

/*! \typedef QHash::key_iterator::pointer
    \internal
*/

/*! \typedef QHash::key_iterator::reference
    \internal
*/

/*! \typedef QHash::key_iterator::value_type
    \internal
*/

/*! \class QHash::iterator
    \inmodule QtCore
    \brief The QHash::iterator class provides an STL-style non-const iterator for QHash and QMultiHash.

    QHash features both \l{STL-style iterators} and \l{Java-style
    iterators}. The STL-style iterators are more low-level and more
    cumbersome to use; on the other hand, they are slightly faster
    and, for developers who already know STL, have the advantage of
    familiarity.

    QHash\<Key, T\>::iterator allows you to iterate over a QHash (or
    QMultiHash) and to modify the value (but not the key) associated
    with a particular key. If you want to iterate over a const QHash,
    you should use QHash::const_iterator. It is generally good
    practice to use QHash::const_iterator on a non-const QHash as
    well, unless you need to change the QHash through the iterator.
    Const iterators are slightly faster, and can improve code
    readability.

    The default QHash::iterator constructor creates an uninitialized
    iterator. You must initialize it using a QHash function like
    QHash::begin(), QHash::end(), or QHash::find() before you can
    start iterating. Here's a typical loop that prints all the (key,
    value) pairs stored in a hash:

    \snippet code/src_corelib_tools_qhash.cpp 17

    Unlike QMap, which orders its items by key, QHash stores its
    items in an arbitrary order.

    Let's see a few examples of things we can do with a
    QHash::iterator that we cannot do with a QHash::const_iterator.
    Here's an example that increments every value stored in the QHash
    by 2:

    \snippet code/src_corelib_tools_qhash.cpp 18

    Here's an example that removes all the items whose key is a
    string that starts with an underscore character:

    \snippet code/src_corelib_tools_qhash.cpp 19

    The call to QHash::erase() removes the item pointed to by the
    iterator from the hash, and returns an iterator to the next item.
    Here's another way of removing an item while iterating:

    \snippet code/src_corelib_tools_qhash.cpp 20

    It might be tempting to write code like this:

    \snippet code/src_corelib_tools_qhash.cpp 21

    However, this will potentially crash in \c{++i}, because \c i is
    a dangling iterator after the call to erase().

    Multiple iterators can be used on the same hash. However, be
    aware that any modification performed directly on the QHash has
    the potential of dramatically changing the order in which the
    items are stored in the hash, as they might cause QHash to rehash
    its internal data structure. There is one notable exception:
    QHash::erase(). This function can safely be called while
    iterating, and won't affect the order of items in the hash. If you
    need to keep iterators over a long period of time, we recommend
    that you use QMap rather than QHash.

    \warning Iterators on implicitly shared containers do not work
    exactly like STL-iterators. You should avoid copying a container
    while iterators are active on that container. For more information,
    read \l{Implicit sharing iterator problem}.

    \sa QHash::const_iterator, QHash::key_iterator, QMutableHashIterator
*/

/*! \fn template <class Key, class T> QHash<Key, T>::iterator::iterator()

    Constructs an uninitialized iterator.

    Functions like key(), value(), and operator++() must not be
    called on an uninitialized iterator. Use operator=() to assign a
    value to it before using it.

    \sa QHash::begin(), QHash::end()
*/

/*! \fn template <class Key, class T> QHash<Key, T>::iterator::iterator(void *node)

    \internal
*/

/*! \fn template <class Key, class T> const Key &QHash<Key, T>::iterator::key() const

    Returns the current item's key as a const reference.

    There is no direct way of changing an item's key through an
    iterator, although it can be done by calling QHash::erase()
    followed by QHash::insert().

    \sa value()
*/

/*! \fn template <class Key, class T> T &QHash<Key, T>::iterator::value() const

    Returns a modifiable reference to the current item's value.

    You can change the value of an item by using value() on
    the left side of an assignment, for example:

    \snippet code/src_corelib_tools_qhash.cpp 22

    \sa key(), operator*()
*/

/*! \fn template <class Key, class T> T &QHash<Key, T>::iterator::operator*() const

    Returns a modifiable reference to the current item's value.

    Same as value().

    \sa key()
*/

/*! \fn template <class Key, class T> T *QHash<Key, T>::iterator::operator->() const

    Returns a pointer to the current item's value.

    \sa value()
*/

/*!
    \fn template <class Key, class T> bool QHash<Key, T>::iterator::operator==(const iterator &other) const
    \fn template <class Key, class T> bool QHash<Key, T>::iterator::operator==(const const_iterator &other) const

    Returns \c true if \a other points to the same item as this
    iterator; otherwise returns \c false.

    \sa operator!=()
*/

/*!
    \fn template <class Key, class T> bool QHash<Key, T>::iterator::operator!=(const iterator &other) const
    \fn template <class Key, class T> bool QHash<Key, T>::iterator::operator!=(const const_iterator &other) const

    Returns \c true if \a other points to a different item than this
    iterator; otherwise returns \c false.

    \sa operator==()
*/

/*!
    \fn template <class Key, class T> QHash<Key, T>::iterator &QHash<Key, T>::iterator::operator++()

    The prefix ++ operator (\c{++i}) advances the iterator to the
    next item in the hash and returns an iterator to the new current
    item.

    Calling this function on QHash::end() leads to undefined results.

    \sa operator--()
*/

/*! \fn template <class Key, class T> QHash<Key, T>::iterator QHash<Key, T>::iterator::operator++(int)

    \overload

    The postfix ++ operator (\c{i++}) advances the iterator to the
    next item in the hash and returns an iterator to the previously
    current item.
*/

/*!
    \fn template <class Key, class T> QHash<Key, T>::iterator &QHash<Key, T>::iterator::operator--()

    The prefix -- operator (\c{--i}) makes the preceding item
    current and returns an iterator pointing to the new current item.

    Calling this function on QHash::begin() leads to undefined
    results.

    \sa operator++()
*/

/*!
    \fn template <class Key, class T> QHash<Key, T>::iterator QHash<Key, T>::iterator::operator--(int)

    \overload

    The postfix -- operator (\c{i--}) makes the preceding item
    current and returns an iterator pointing to the previously
    current item.
*/

/*! \fn template <class Key, class T> QHash<Key, T>::iterator QHash<Key, T>::iterator::operator+(int j) const

    Returns an iterator to the item at \a j positions forward from
    this iterator. (If \a j is negative, the iterator goes backward.)

    This operation can be slow for large \a j values.

    \sa operator-()

*/

/*! \fn template <class Key, class T> QHash<Key, T>::iterator QHash<Key, T>::iterator::operator-(int j) const

    Returns an iterator to the item at \a j positions backward from
    this iterator. (If \a j is negative, the iterator goes forward.)

    This operation can be slow for large \a j values.

    \sa operator+()
*/

/*! \fn template <class Key, class T> QHash<Key, T>::iterator &QHash<Key, T>::iterator::operator+=(int j)

    Advances the iterator by \a j items. (If \a j is negative, the
    iterator goes backward.)

    \sa operator-=(), operator+()
*/

/*! \fn template <class Key, class T> QHash<Key, T>::iterator &QHash<Key, T>::iterator::operator-=(int j)

    Makes the iterator go back by \a j items. (If \a j is negative,
    the iterator goes forward.)

    \sa operator+=(), operator-()
*/

/*! \class QHash::const_iterator
    \inmodule QtCore
    \brief The QHash::const_iterator class provides an STL-style const iterator for QHash and QMultiHash.

    QHash features both \l{STL-style iterators} and \l{Java-style
    iterators}. The STL-style iterators are more low-level and more
    cumbersome to use; on the other hand, they are slightly faster
    and, for developers who already know STL, have the advantage of
    familiarity.

    QHash\<Key, T\>::const_iterator allows you to iterate over a
    QHash (or a QMultiHash). If you want to modify the QHash as you
    iterate over it, you must use QHash::iterator instead. It is
    generally good practice to use QHash::const_iterator on a
    non-const QHash as well, unless you need to change the QHash
    through the iterator. Const iterators are slightly faster, and
    can improve code readability.

    The default QHash::const_iterator constructor creates an
    uninitialized iterator. You must initialize it using a QHash
    function like QHash::constBegin(), QHash::constEnd(), or
    QHash::find() before you can start iterating. Here's a typical
    loop that prints all the (key, value) pairs stored in a hash:

    \snippet code/src_corelib_tools_qhash.cpp 23

    Unlike QMap, which orders its items by key, QHash stores its
    items in an arbitrary order. The only guarantee is that items that
    share the same key (because they were inserted using
    a QMultiHash) will appear consecutively, from the most
    recently to the least recently inserted value.

    Multiple iterators can be used on the same hash. However, be aware
    that any modification performed directly on the QHash has the
    potential of dramatically changing the order in which the items
    are stored in the hash, as they might cause QHash to rehash its
    internal data structure. If you need to keep iterators over a long
    period of time, we recommend that you use QMap rather than QHash.

    \warning Iterators on implicitly shared containers do not work
    exactly like STL-iterators. You should avoid copying a container
    while iterators are active on that container. For more information,
    read \l{Implicit sharing iterator problem}.

    \sa QHash::iterator, QHashIterator
*/

/*! \fn template <class Key, class T> QHash<Key, T>::const_iterator::const_iterator()

    Constructs an uninitialized iterator.

    Functions like key(), value(), and operator++() must not be
    called on an uninitialized iterator. Use operator=() to assign a
    value to it before using it.

    \sa QHash::constBegin(), QHash::constEnd()
*/

/*! \fn template <class Key, class T> QHash<Key, T>::const_iterator::const_iterator(void *node)

    \internal
*/

/*! \fn template <class Key, class T> QHash<Key, T>::const_iterator::const_iterator(const iterator &other)

    Constructs a copy of \a other.
*/

/*! \fn template <class Key, class T> const Key &QHash<Key, T>::const_iterator::key() const

    Returns the current item's key.

    \sa value()
*/

/*! \fn template <class Key, class T> const T &QHash<Key, T>::const_iterator::value() const

    Returns the current item's value.

    \sa key(), operator*()
*/

/*! \fn template <class Key, class T> const T &QHash<Key, T>::const_iterator::operator*() const

    Returns the current item's value.

    Same as value().

    \sa key()
*/

/*! \fn template <class Key, class T> const T *QHash<Key, T>::const_iterator::operator->() const

    Returns a pointer to the current item's value.

    \sa value()
*/

/*! \fn template <class Key, class T> bool QHash<Key, T>::const_iterator::operator==(const const_iterator &other) const

    Returns \c true if \a other points to the same item as this
    iterator; otherwise returns \c false.

    \sa operator!=()
*/

/*! \fn template <class Key, class T> bool QHash<Key, T>::const_iterator::operator!=(const const_iterator &other) const

    Returns \c true if \a other points to a different item than this
    iterator; otherwise returns \c false.

    \sa operator==()
*/

/*!
    \fn template <class Key, class T> QHash<Key, T>::const_iterator &QHash<Key, T>::const_iterator::operator++()

    The prefix ++ operator (\c{++i}) advances the iterator to the
    next item in the hash and returns an iterator to the new current
    item.

    Calling this function on QHash::end() leads to undefined results.

    \sa operator--()
*/

/*! \fn template <class Key, class T> QHash<Key, T>::const_iterator QHash<Key, T>::const_iterator::operator++(int)

    \overload

    The postfix ++ operator (\c{i++}) advances the iterator to the
    next item in the hash and returns an iterator to the previously
    current item.
*/

/*! \fn template <class Key, class T> QHash<Key, T>::const_iterator &QHash<Key, T>::const_iterator::operator--()

    The prefix -- operator (\c{--i}) makes the preceding item
    current and returns an iterator pointing to the new current item.

    Calling this function on QHash::begin() leads to undefined
    results.

    \sa operator++()
*/

/*! \fn template <class Key, class T> QHash<Key, T>::const_iterator QHash<Key, T>::const_iterator::operator--(int)

    \overload

    The postfix -- operator (\c{i--}) makes the preceding item
    current and returns an iterator pointing to the previously
    current item.
*/

/*! \fn template <class Key, class T> QHash<Key, T>::const_iterator QHash<Key, T>::const_iterator::operator+(int j) const

    Returns an iterator to the item at \a j positions forward from
    this iterator. (If \a j is negative, the iterator goes backward.)

    This operation can be slow for large \a j values.

    \sa operator-()
*/

/*! \fn template <class Key, class T> QHash<Key, T>::const_iterator QHash<Key, T>::const_iterator::operator-(int j) const

    Returns an iterator to the item at \a j positions backward from
    this iterator. (If \a j is negative, the iterator goes forward.)

    This operation can be slow for large \a j values.

    \sa operator+()
*/

/*! \fn template <class Key, class T> QHash<Key, T>::const_iterator &QHash<Key, T>::const_iterator::operator+=(int j)

    Advances the iterator by \a j items. (If \a j is negative, the
    iterator goes backward.)

    This operation can be slow for large \a j values.

    \sa operator-=(), operator+()
*/

/*! \fn template <class Key, class T> QHash<Key, T>::const_iterator &QHash<Key, T>::const_iterator::operator-=(int j)

    Makes the iterator go back by \a j items. (If \a j is negative,
    the iterator goes forward.)

    This operation can be slow for large \a j values.

    \sa operator+=(), operator-()
*/

/*! \class QHash::key_iterator
    \inmodule QtCore
    \since 5.6
    \brief The QHash::key_iterator class provides an STL-style const iterator for QHash and QMultiHash keys.

    QHash::key_iterator is essentially the same as QHash::const_iterator
    with the difference that operator*() and operator->() return a key
    instead of a value.

    For most uses QHash::iterator and QHash::const_iterator should be used,
    you can easily access the key by calling QHash::iterator::key():

    \snippet code/src_corelib_tools_qhash.cpp 27

    However, to have interoperability between QHash's keys and STL-style
    algorithms we need an iterator that dereferences to a key instead
    of a value. With QHash::key_iterator we can apply an algorithm to a
    range of keys without having to call QHash::keys(), which is inefficient
    as it costs one QHash iteration and memory allocation to create a temporary
    QList.

    \snippet code/src_corelib_tools_qhash.cpp 28

    QHash::key_iterator is const, it's not possible to modify the key.

    The default QHash::key_iterator constructor creates an uninitialized
    iterator. You must initialize it using a QHash function like
    QHash::keyBegin() or QHash::keyEnd().

    \warning Iterators on implicitly shared containers do not work
    exactly like STL-iterators. You should avoid copying a container
    while iterators are active on that container. For more information,
    read \l{Implicit sharing iterator problem}.

    \sa QHash::const_iterator, QHash::iterator
*/

/*! \fn template <class Key, class T> const T &QHash<Key, T>::key_iterator::operator*() const

    Returns the current item's key.
*/

/*! \fn template <class Key, class T> const T *QHash<Key, T>::key_iterator::operator->() const

    Returns a pointer to the current item's key.
*/

/*! \fn template <class Key, class T> bool QHash<Key, T>::key_iterator::operator==(key_iterator other) const

    Returns \c true if \a other points to the same item as this
    iterator; otherwise returns \c false.

    \sa operator!=()
*/

/*! \fn template <class Key, class T> bool QHash<Key, T>::key_iterator::operator!=(key_iterator other) const

    Returns \c true if \a other points to a different item than this
    iterator; otherwise returns \c false.

    \sa operator==()
*/

/*!
    \fn template <class Key, class T> QHash<Key, T>::key_iterator &QHash<Key, T>::key_iterator::operator++()

    The prefix ++ operator (\c{++i}) advances the iterator to the
    next item in the hash and returns an iterator to the new current
    item.

    Calling this function on QHash::keyEnd() leads to undefined results.

    \sa operator--()
*/

/*! \fn template <class Key, class T> QHash<Key, T>::key_iterator QHash<Key, T>::key_iterator::operator++(int)

    \overload

    The postfix ++ operator (\c{i++}) advances the iterator to the
    next item in the hash and returns an iterator to the previous
    item.
*/

/*! \fn template <class Key, class T> QHash<Key, T>::key_iterator &QHash<Key, T>::key_iterator::operator--()

    The prefix -- operator (\c{--i}) makes the preceding item
    current and returns an iterator pointing to the new current item.

    Calling this function on QHash::keyBegin() leads to undefined
    results.

    \sa operator++()
*/

/*! \fn template <class Key, class T> QHash<Key, T>::key_iterator QHash<Key, T>::key_iterator::operator--(int)

    \overload

    The postfix -- operator (\c{i--}) makes the preceding item
    current and returns an iterator pointing to the previous
    item.
*/

/*! \fn template <class Key, class T> const_iterator QHash<Key, T>::key_iterator::base() const
    Returns the underlying const_iterator this key_iterator is based on.
*/

/*! \typedef QHash::const_key_value_iterator
    \inmodule QtCore
    \since 5.10
    \brief The QMap::const_key_value_iterator typedef provides an STL-style const iterator for QHash and QMultiHash.

    QHash::const_key_value_iterator is essentially the same as QHash::const_iterator
    with the difference that operator*() returns a key/value pair instead of a
    value.

    \sa QKeyValueIterator
*/

/*! \typedef QHash::key_value_iterator
    \inmodule QtCore
    \since 5.10
    \brief The QMap::key_value_iterator typedef provides an STL-style iterator for QHash and QMultiHash.

    QHash::key_value_iterator is essentially the same as QHash::iterator
    with the difference that operator*() returns a key/value pair instead of a
    value.

    \sa QKeyValueIterator
*/

/*! \fn template <class Key, class T> QDataStream &operator<<(QDataStream &out, const QHash<Key, T>& hash)
    \relates QHash

    Writes the hash \a hash to stream \a out.

    This function requires the key and value types to implement \c
    operator<<().

    \sa {Serializing Qt Data Types}
*/

/*! \fn template <class Key, class T> QDataStream &operator>>(QDataStream &in, QHash<Key, T> &hash)
    \relates QHash

    Reads a hash from stream \a in into \a hash.

    This function requires the key and value types to implement \c
    operator>>().

    \sa {Serializing Qt Data Types}
*/

/*! \class QMultiHash
    \inmodule QtCore
    \brief The QMultiHash class is a convenience QHash subclass that provides multi-valued hashes.

    \ingroup tools
    \ingroup shared

    \reentrant

    QMultiHash\<Key, T\> is one of Qt's generic \l{container classes}.
    It inherits QHash and extends it with a few convenience functions
    that make it more suitable than QHash for storing multi-valued
    hashes. A multi-valued hash is a hash that allows multiple values
    with the same key.

    Because QMultiHash inherits QHash, all of QHash's functionality also
    applies to QMultiHash. For example, you can use isEmpty() to test
    whether the hash is empty, and you can traverse a QMultiHash using
    QHash's iterator classes (for example, QHashIterator). But opposed to
    QHash, it provides an insert() function will allow the insertion of
    multiple items with the same key. The replace() function corresponds to
    QHash::insert(). It also provides convenient operator+() and
    operator+=().

    Unlike QMultiMap, QMultiHash does not provide and ordering of the
    inserted items. The only guarantee is that items that
    share the same key will appear consecutively, from the most
    recently to the least recently inserted value.

    Example:
    \snippet code/src_corelib_tools_qhash.cpp 24

    Unlike QHash, QMultiHash provides no operator[]. Use value() or
    replace() if you want to access the most recently inserted item
    with a certain key.

    If you want to retrieve all the values for a single key, you can
    use values(const Key &key), which returns a QList<T>:

    \snippet code/src_corelib_tools_qhash.cpp 25

    The items that share the same key are available from most
    recently to least recently inserted.

    A more efficient approach is to call find() to get
    the STL-style iterator for the first item with a key and iterate from
    there:

    \snippet code/src_corelib_tools_qhash.cpp 26

    QMultiHash's key and value data types must be \l{assignable data
    types}. You cannot, for example, store a QWidget as a value;
    instead, store a QWidget *. In addition, QMultiHash's key type
    must provide operator==(), and there must also be a qHash() function
   in the type's namespace that returns a hash value for an argument of the
    key's type. See the QHash documentation for details.

    \sa QHash, QHashIterator, QMutableHashIterator, QMultiMap
*/

/*! \fn template <class Key, class T> QMultiHash<Key, T>::QMultiHash()

    Constructs an empty hash.
*/

/*! \fn template <class Key, class T> QMultiHash<Key, T>::QMultiHash(std::initializer_list<std::pair<Key,T> > list)
    \since 5.1

    Constructs a multi-hash with a copy of each of the elements in the
    initializer list \a list.

    This function is only available if the program is being
    compiled in C++11 mode.
*/

/*! \fn template <class Key, class T> QMultiHash<Key, T>::QMultiHash(const QHash<Key, T> &other)

    Constructs a copy of \a other (which can be a QHash or a
    QMultiHash).

    \sa operator=()
*/

/*! \fn template <class Key, class T> template <class InputIterator> QMultiHash::QMultiHash(InputIterator begin, InputIterator end)
    \since 5.14

    Constructs a multi-hash with a copy of each of the elements in the iterator range
    [\a begin, \a end). Either the elements iterated by the range must be
    objects with \c{first} and \c{second} data members (like \c{QPair},
    \c{std::pair}, etc.) convertible to \c Key and to \c T respectively; or the
    iterators must have \c{key()} and \c{value()} member functions, returning a
    key convertible to \c Key and a value convertible to \c T respectively.
*/

/*! \fn template <class Key, class T> QMultiHash<Key, T>::iterator QMultiHash<Key, T>::replace(const Key &key, const T &value)

    Inserts a new item with the \a key and a value of \a value.

    If there is already an item with the \a key, that item's value
    is replaced with \a value.

    If there are multiple items with the \a key, the most
    recently inserted item's value is replaced with \a value.

    \sa insert()
*/

/*! \fn template <class Key, class T> QMultiHash<Key, T>::iterator QMultiHash<Key, T>::insert(const Key &key, const T &value)

    Inserts a new item with the \a key and a value of \a value.

    If there is already an item with the same key in the hash, this
    function will simply create a new one. (This behavior is
    different from replace(), which overwrites the value of an
    existing item.)

    \sa replace()
*/

/*! \fn template <class Key, class T> QMultiHash &QMultiHash<Key, T>::unite(const QMultiHash &other)
    \since 5.13

    Inserts all the items in the \a other hash into this hash
    and returns a reference to this hash.

    \sa insert()
*/

/*! \fn template <class Key, class T> QList<Key> QHash<Key, T>::uniqueKeys() const
    \since 5.13

    Returns a list containing all the keys in the map. Keys that occur multiple
    times in the map occur only once in the returned list.

    \sa keys(), values()
*/

/*! \fn template <class Key, class T> QList<T> QMultiHash<Key, T>::values(const Key &key) const
    \overload

    Returns a list of all the values associated with the \a key,
    from the most recently inserted to the least recently inserted.

    \sa count(), insert()
*/

/*! \fn template <class Key, class T> QMultiHash &QMultiHash<Key, T>::operator+=(const QMultiHash &other)

    Inserts all the items in the \a other hash into this hash
    and returns a reference to this hash.

    \sa unit(), insert()
*/

/*! \fn template <class Key, class T> QMultiHash QMultiHash<Key, T>::operator+(const QMultiHash &other) const

    Returns a hash that contains all the items in this hash in
    addition to all the items in \a other. If a key is common to both
    hashes, the resulting hash will contain the key multiple times.

    \sa operator+=()
*/

/*!
    \fn template <class Key, class T> bool QMultiHash<Key, T>::contains(const Key &key, const T &value) const
    \since 4.3

    Returns \c true if the hash contains an item with the \a key and
    \a value; otherwise returns \c false.

    \sa QHash::contains()
*/

/*!
    \fn template <class Key, class T> int QMultiHash<Key, T>::remove(const Key &key, const T &value)
    \since 4.3

    Removes all the items that have the \a key and the value \a
    value from the hash. Returns the number of items removed.

    \sa QHash::remove()
*/

/*! \fn template <class Key, class T> int QMultiHash<Key, T>::count(const Key &key) const

    Returns the number of items associated with the \a key.

    \sa contains(), insert()
*/

/*!
    \fn template <class Key, class T> int QMultiHash<Key, T>::count(const Key &key, const T &value) const
    \since 4.3

    Returns the number of items with the \a key and \a value.

    \sa QHash::count()
*/

/*!
    \fn template <class Key, class T> typename QHash<Key, T>::iterator QMultiHash<Key, T>::find(const Key &key, const T &value)
    \since 4.3

    Returns an iterator pointing to the item with the \a key and \a value.
    If the hash contains no such item, the function returns end().

    If the hash contains multiple items with the \a key and \a value, the
    iterator returned points to the most recently inserted item.

    \sa QHash::find()
*/

/*!
    \fn template <class Key, class T> typename QHash<Key, T>::const_iterator QMultiHash<Key, T>::find(const Key &key, const T &value) const
    \since 4.3
    \overload
*/

/*!
    \fn template <class Key, class T> typename QHash<Key, T>::const_iterator QMultiHash<Key, T>::constFind(const Key &key, const T &value) const
    \since 4.3

    Returns an iterator pointing to the item with the \a key and the
    \a value in the hash.

    If the hash contains no such item, the function returns
    constEnd().

    \sa QHash::constFind()
*/

/*!
    \fn template <class Key, class T> uint qHash(const QHash<Key, T> &key, uint seed = 0)
    \since 5.8
    \relates QHash

    Returns the hash value for the \a key, using \a seed to seed the calculation.

    Type \c T must be supported by qHash().
*/

/*!
    \fn template <class Key, class T> uint qHash(const QMultiHash<Key, T> &key, uint seed = 0)
    \since 5.8
    \relates QMultiHash

    Returns the hash value for the \a key, using \a seed to seed the calculation.

    Type \c T must be supported by qHash().
*/

QT_END_NAMESPACE