summaryrefslogtreecommitdiffstats
path: root/src/corelib/kernel/qabstractitemmodel.cpp
blob: 8b9cec85a6932cfe35a6d85973f22186f05730f8 (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
2765
2766
2767
2768
2769
2770
2771
2772
2773
2774
2775
2776
2777
2778
2779
2780
2781
2782
2783
2784
2785
2786
2787
2788
2789
2790
2791
2792
2793
2794
2795
2796
2797
2798
2799
2800
2801
2802
2803
2804
2805
2806
2807
2808
2809
2810
2811
2812
2813
2814
2815
2816
2817
2818
2819
2820
2821
2822
2823
2824
2825
2826
2827
2828
2829
2830
2831
2832
2833
2834
2835
2836
2837
2838
2839
2840
2841
2842
2843
2844
2845
2846
2847
2848
2849
2850
2851
2852
2853
2854
2855
2856
2857
2858
2859
2860
2861
2862
2863
2864
2865
2866
2867
2868
2869
2870
2871
2872
2873
2874
2875
2876
2877
2878
2879
2880
2881
2882
2883
2884
2885
2886
2887
2888
2889
2890
2891
2892
2893
2894
2895
2896
2897
2898
2899
2900
2901
2902
2903
2904
2905
2906
2907
2908
2909
2910
2911
2912
2913
2914
2915
2916
2917
2918
2919
2920
2921
2922
2923
2924
2925
2926
2927
2928
2929
2930
2931
2932
2933
2934
2935
2936
2937
2938
2939
2940
2941
2942
2943
2944
2945
2946
2947
2948
2949
2950
2951
2952
2953
2954
2955
2956
2957
2958
2959
2960
2961
2962
2963
2964
2965
2966
2967
2968
2969
2970
2971
2972
2973
2974
2975
2976
2977
2978
2979
2980
2981
2982
2983
2984
2985
2986
2987
2988
2989
2990
2991
2992
2993
2994
2995
2996
2997
2998
2999
3000
3001
3002
3003
3004
3005
3006
3007
3008
3009
3010
3011
3012
3013
3014
3015
3016
3017
3018
3019
3020
3021
3022
3023
3024
3025
3026
3027
3028
3029
3030
3031
3032
3033
3034
3035
3036
3037
3038
3039
3040
3041
3042
3043
3044
3045
3046
3047
3048
3049
3050
3051
3052
3053
3054
3055
3056
3057
3058
3059
3060
3061
3062
3063
3064
3065
3066
3067
3068
3069
3070
3071
3072
3073
3074
3075
3076
3077
3078
3079
3080
3081
3082
3083
3084
3085
3086
3087
3088
3089
3090
3091
3092
3093
3094
3095
3096
3097
3098
3099
3100
3101
3102
3103
3104
3105
3106
3107
3108
3109
3110
3111
3112
3113
3114
3115
3116
3117
3118
3119
3120
3121
3122
3123
3124
3125
3126
3127
3128
3129
3130
3131
3132
3133
3134
3135
3136
3137
3138
3139
3140
3141
3142
3143
3144
3145
3146
3147
3148
3149
3150
3151
3152
3153
3154
3155
3156
3157
3158
3159
3160
3161
3162
3163
3164
3165
3166
3167
3168
3169
3170
3171
3172
3173
3174
3175
3176
3177
3178
3179
3180
3181
3182
3183
3184
3185
3186
3187
3188
3189
3190
3191
3192
3193
3194
3195
3196
3197
3198
3199
3200
3201
3202
3203
3204
3205
3206
3207
3208
3209
3210
3211
3212
3213
3214
3215
3216
3217
3218
3219
3220
3221
3222
3223
3224
3225
3226
3227
3228
3229
3230
3231
3232
3233
3234
3235
3236
3237
3238
3239
3240
3241
3242
3243
3244
3245
3246
3247
3248
3249
3250
3251
3252
3253
3254
3255
3256
3257
3258
3259
3260
3261
3262
3263
3264
3265
3266
3267
3268
3269
3270
3271
3272
3273
3274
3275
3276
3277
3278
3279
3280
3281
3282
3283
3284
3285
3286
3287
3288
3289
3290
3291
3292
3293
3294
3295
3296
3297
3298
3299
3300
3301
3302
3303
3304
3305
3306
3307
3308
3309
3310
3311
3312
3313
3314
3315
3316
3317
3318
3319
3320
3321
3322
3323
3324
3325
3326
3327
3328
3329
3330
3331
3332
3333
3334
3335
3336
3337
3338
3339
3340
3341
3342
3343
3344
3345
3346
3347
3348
3349
3350
3351
3352
3353
3354
3355
3356
3357
3358
3359
3360
/****************************************************************************
**
** Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).
** All rights reserved.
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of the QtCore module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** No Commercial Usage
** This file contains pre-release code and may not be distributed.
** You may use this file in accordance with the terms and conditions
** contained in the Technology Preview License Agreement accompanying
** this package.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Nokia gives you certain additional
** rights.  These rights are described in the Nokia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** If you have questions regarding the use of this file, please contact
** Nokia at qt-info@nokia.com.
**
**
**
**
**
**
**
**
** $QT_END_LICENSE$
**
****************************************************************************/

#include "qabstractitemmodel.h"
#include <private/qabstractitemmodel_p.h>
#include <qdatastream.h>
#include <qstringlist.h>
#include <qsize.h>
#include <qmimedata.h>
#include <qdebug.h>
#include <qvector.h>
#include <qstack.h>
#include <qbitarray.h>

#include <limits.h>

QT_BEGIN_NAMESPACE

QPersistentModelIndexData *QPersistentModelIndexData::create(const QModelIndex &index)
{
    Q_ASSERT(index.isValid()); // we will _never_ insert an invalid index in the list
    QPersistentModelIndexData *d = 0;
    QAbstractItemModel *model = const_cast<QAbstractItemModel *>(index.model());
    QHash<QModelIndex, QPersistentModelIndexData *> &indexes = model->d_func()->persistent.indexes;
    const QHash<QModelIndex, QPersistentModelIndexData *>::iterator it = indexes.find(index);
    if (it != indexes.end()) {
        d = (*it);
    } else {
        d = new QPersistentModelIndexData(index);
        indexes.insert(index, d);
    }
    Q_ASSERT(d);
    return d;
}

void QPersistentModelIndexData::destroy(QPersistentModelIndexData *data)
{
    Q_ASSERT(data);
    Q_ASSERT(data->ref == 0);
    QAbstractItemModel *model = const_cast<QAbstractItemModel *>(data->model);
    // a valid persistent model index with a null model pointer can only happen if the model was destroyed
    if (model) {
        QAbstractItemModelPrivate *p = model->d_func();
        Q_ASSERT(p);
        p->removePersistentIndexData(data);
    }
    delete data;
}

/*!
  \class QPersistentModelIndex

  \brief The QPersistentModelIndex class is used to locate data in a data model.

  \ingroup model-view

  A QPersistentModelIndex is a model index that can be stored by an
  application, and later used to access information in a model.
  Unlike the QModelIndex class, it is safe to store a
  QPersistentModelIndex since the model will ensure that references
  to items will continue to be valid as long as they can be accessed
  by the model.

  It is good practice to check that persistent model indexes are valid
  before using them.

  \sa {Model/View Programming}, QModelIndex, QAbstractItemModel
*/


/*!
  \fn QPersistentModelIndex::QPersistentModelIndex()

  \internal
*/

QPersistentModelIndex::QPersistentModelIndex()
    : d(0)
{
}

/*!
  \fn QPersistentModelIndex::QPersistentModelIndex(const QPersistentModelIndex &other)

  Creates a new QPersistentModelIndex that is a copy of the \a other persistent
  model index.
*/

QPersistentModelIndex::QPersistentModelIndex(const QPersistentModelIndex &other)
    : d(other.d)
{
    if (d) d->ref.ref();
}

/*!
    Creates a new QPersistentModelIndex that is a copy of the model \a index.
*/

QPersistentModelIndex::QPersistentModelIndex(const QModelIndex &index)
    : d(0)
{
    if (index.isValid()) {
        d = QPersistentModelIndexData::create(index);
        d->ref.ref();
    }
}

/*!
    \fn QPersistentModelIndex::~QPersistentModelIndex()

    \internal
*/

QPersistentModelIndex::~QPersistentModelIndex()
{
    if (d && !d->ref.deref()) {
        QPersistentModelIndexData::destroy(d);
        d = 0;
    }
}

/*!
  Returns true if this persistent model index is equal to the \a other
  persistent model index; otherwise returns false.

  All values in the persistent model index are used when comparing
  with another persistent model index.
*/

bool QPersistentModelIndex::operator==(const QPersistentModelIndex &other) const
{
    if (d && other.d)
        return d->index == other.d->index;
    return d == other.d;
}

/*!
    \since 4.1

    Returns true if this persistent model index is smaller than the \a other
    persistent model index; otherwise returns false.

    All values in the persistent model index are used when comparing
    with another persistent model index.
*/

bool QPersistentModelIndex::operator<(const QPersistentModelIndex &other) const
{
    if (d && other.d)
        return d->index < other.d->index;

    return d < other.d;
}

/*!
    \fn bool QPersistentModelIndex::operator!=(const QPersistentModelIndex &other) const
    \since 4.2

    Returns true if this persistent model index is not equal to the \a
    other persistent model index; otherwise returns false.
*/

/*!
    Sets the persistent model index to refer to the same item in a model
    as the \a other persistent model index.
*/

QPersistentModelIndex &QPersistentModelIndex::operator=(const QPersistentModelIndex &other)
{
    if (d == other.d)
        return *this;
    if (d && !d->ref.deref())
        QPersistentModelIndexData::destroy(d);
    d = other.d;
    if (d) d->ref.ref();
    return *this;
}

/*!
    Sets the persistent model index to refer to the same item in a model
    as the \a other model index.
*/

QPersistentModelIndex &QPersistentModelIndex::operator=(const QModelIndex &other)
{
    if (d && !d->ref.deref())
        QPersistentModelIndexData::destroy(d);
    if (other.isValid()) {
        d = QPersistentModelIndexData::create(other);
        if (d) d->ref.ref();
    } else {
        d = 0;
    }
    return *this;
}

/*!
  \fn QPersistentModelIndex::operator const QModelIndex&() const

  Cast operator that returns a const QModelIndex&.
*/

QPersistentModelIndex::operator const QModelIndex&() const
{
    static const QModelIndex invalid;
    if (d)
        return d->index;
    return invalid;
}

/*!
    \fn bool QPersistentModelIndex::operator==(const QModelIndex &other) const

    Returns true if this persistent model index refers to the same location as
    the \a other model index; otherwise returns false.

    All values in the persistent model index are used when comparing with
    another model index.
*/

bool QPersistentModelIndex::operator==(const QModelIndex &other) const
{
    if (d)
        return d->index == other;
    return !other.isValid();
}

/*!
    \fn bool QPersistentModelIndex::operator!=(const QModelIndex &other) const

    Returns true if this persistent model index does not refer to the same
    location as the \a other model index; otherwise returns false.
*/

bool QPersistentModelIndex::operator!=(const QModelIndex &other) const
{
    if (d)
        return d->index != other;
    return other.isValid();
}

/*!
    \fn int QPersistentModelIndex::row() const

    Returns the row this persistent model index refers to.
*/

int QPersistentModelIndex::row() const
{
    if (d)
        return d->index.row();
    return -1;
}

/*!
    \fn int QPersistentModelIndex::column() const

    Returns the column this persistent model index refers to.
*/

int QPersistentModelIndex::column() const
{
    if (d)
        return d->index.column();
    return -1;
}

/*!
    \fn void *QPersistentModelIndex::internalPointer() const

    \internal

    Returns a \c{void} \c{*} pointer used by the model to associate the index with
    the internal data structure.
*/

void *QPersistentModelIndex::internalPointer() const
{
    if (d)
        return d->index.internalPointer();
    return 0;
}

/*!
    \fn void *QPersistentModelIndex::internalId() const

    \internal

    Returns a \c{qint64} used by the model to associate the index with
    the internal data structure.
*/

qint64 QPersistentModelIndex::internalId() const
{
    if (d)
        return d->index.internalId();
    return 0;
}

/*!
    Returns the parent QModelIndex for this persistent index, or an invalid
    QModelIndex if it has no parent.

    \sa child() sibling() model()
*/
QModelIndex QPersistentModelIndex::parent() const
{
    if (d)
        return d->index.parent();
    return QModelIndex();
}

/*!
    Returns the sibling at \a row and \a column or an invalid QModelIndex if
    there is no sibling at this position.

    \sa parent() child()
*/

QModelIndex QPersistentModelIndex::sibling(int row, int column) const
{
    if (d)
        return d->index.sibling(row, column);
    return QModelIndex();
}

/*!
    Returns the child of the model index that is stored in the given \a row
    and \a column.

    \sa parent() sibling()
*/

QModelIndex QPersistentModelIndex::child(int row, int column) const
{
    if (d)
        return d->index.child(row, column);
    return QModelIndex();
}

/*!
    Returns the data for the given \a role for the item referred to by the
    index.

    \sa Qt::ItemDataRole, QAbstractItemModel::setData()
*/
QVariant QPersistentModelIndex::data(int role) const
{
    if (d)
        return d->index.data(role);
    return QVariant();
}

/*!
    \since 4.2

    Returns the flags for the item referred to by the index.
*/
Qt::ItemFlags QPersistentModelIndex::flags() const
{
    if (d)
        return d->index.flags();
    return 0;
}

/*!
    Returns the model that the index belongs to.
*/
const QAbstractItemModel *QPersistentModelIndex::model() const
{
    if (d)
        return d->index.model();
    return 0;
}

/*!
    \fn bool QPersistentModelIndex::isValid() const

    Returns true if this persistent model index is valid; otherwise returns
    false.

    A valid index belongs to a model, and has non-negative row and column
    numbers.

    \sa model(), row(), column()
*/

bool QPersistentModelIndex::isValid() const
{
    return d && d->index.isValid();
}

#ifndef QT_NO_DEBUG_STREAM
QDebug operator<<(QDebug dbg, const QModelIndex &idx)
{
#ifndef Q_BROKEN_DEBUG_STREAM
    dbg.nospace() << "QModelIndex(" << idx.row() << ',' << idx.column()
                  << ',' << idx.internalPointer() << ',' << idx.model() << ')';
    return dbg.space();
#else
    qWarning("This compiler doesn't support streaming QModelIndex to QDebug");
    return dbg;
    Q_UNUSED(idx);
#endif
}

QDebug operator<<(QDebug dbg, const QPersistentModelIndex &idx)
{
    if (idx.d)
        dbg << idx.d->index;
    else
        dbg << QModelIndex();
    return dbg;
}
#endif

class QEmptyItemModel : public QAbstractItemModel
{
public:
    explicit QEmptyItemModel(QObject *parent = 0) : QAbstractItemModel(parent) {}
    QModelIndex index(int, int, const QModelIndex &) const { return QModelIndex(); }
    QModelIndex parent(const QModelIndex &) const { return QModelIndex(); }
    int rowCount(const QModelIndex &) const { return 0; }
    int columnCount(const QModelIndex &) const { return 0; }
    bool hasChildren(const QModelIndex &) const { return false; }
    QVariant data(const QModelIndex &, int) const { return QVariant(); }
};

Q_GLOBAL_STATIC(QEmptyItemModel, qEmptyModel)

QAbstractItemModel *QAbstractItemModelPrivate::staticEmptyModel()
{
    return qEmptyModel();
}

namespace {
    struct DefaultRoleNames : public QHash<int, QByteArray>
    {
        DefaultRoleNames() {
            (*this)[Qt::DisplayRole] = "display";
            (*this)[Qt::DecorationRole] = "decoration";
            (*this)[Qt::EditRole] = "edit";
            (*this)[Qt::ToolTipRole] = "toolTip";
            (*this)[Qt::StatusTipRole] = "statusTip";
            (*this)[Qt::WhatsThisRole] = "whatsThis";
        }
    };
}

Q_GLOBAL_STATIC(DefaultRoleNames, qDefaultRoleNames)

const QHash<int,QByteArray> &QAbstractItemModelPrivate::defaultRoleNames()
{
    return *qDefaultRoleNames();
}


static uint typeOfVariant(const QVariant &value)
{
    //return 0 for integer, 1 for floating point and 2 for other
    switch (value.userType()) {
        case QVariant::Bool:
        case QVariant::Int:
        case QVariant::UInt:
        case QVariant::LongLong:
        case QVariant::ULongLong:
        case QVariant::Char:
        case QMetaType::Short:
        case QMetaType::UShort:
        case QMetaType::UChar:
        case QMetaType::ULong:
        case QMetaType::Long:
            return 0;
        case QVariant::Double:
        case QMetaType::Float:
            return 1;
        default:
            return 2;
    }
}

/*!
    \internal
    return true if \a value contains a numerical type

    This function is used by our Q{Tree,Widget,Table}WidgetModel classes to sort.
*/
bool QAbstractItemModelPrivate::variantLessThan(const QVariant &v1, const QVariant &v2)
{
    switch(qMax(typeOfVariant(v1), typeOfVariant(v2)))
    {
    case 0: //integer type
        return v1.toLongLong() < v2.toLongLong();
    case 1: //floating point
        return v1.toReal() < v2.toReal();
    default:
        return v1.toString() < v2.toString();
    }
}

void QAbstractItemModelPrivate::removePersistentIndexData(QPersistentModelIndexData *data)
{
    if (data->index.isValid()) {
        int removed = persistent.indexes.remove(data->index);
        Q_ASSERT_X(removed == 1, "QPersistentModelIndex::~QPersistentModelIndex",
                   "persistent model indexes corrupted"); //maybe the index was somewhat invalid?
        // This assert may happen if the model use changePersistentIndex in a way that could result on two
        // QPersistentModelIndex pointing to the same index.
        Q_UNUSED(removed);
    }
    // make sure our optimization still works
    for (int i = persistent.moved.count() - 1; i >= 0; --i) {
        int idx = persistent.moved[i].indexOf(data);
        if (idx >= 0)
            persistent.moved[i].remove(idx);
    }
    // update the references to invalidated persistent indexes
    for (int i = persistent.invalidated.count() - 1; i >= 0; --i) {
        int idx = persistent.invalidated[i].indexOf(data);
        if (idx >= 0)
            persistent.invalidated[i].remove(idx);
    }

}

void QAbstractItemModelPrivate::rowsAboutToBeInserted(const QModelIndex &parent,
                                                      int first, int last)
{
    Q_Q(QAbstractItemModel);
    Q_UNUSED(last);
    QVector<QPersistentModelIndexData *> persistent_moved;
    if (first < q->rowCount(parent)) {
        for (QHash<QModelIndex, QPersistentModelIndexData *>::const_iterator it = persistent.indexes.constBegin();
             it != persistent.indexes.constEnd(); ++it) {
            QPersistentModelIndexData *data = *it;
            const QModelIndex &index = data->index;
            if (index.row() >= first && index.isValid() && index.parent() == parent) {
                persistent_moved.append(data);
            }
        }
    }
    persistent.moved.push(persistent_moved);
}

void QAbstractItemModelPrivate::rowsInserted(const QModelIndex &parent,
                                             int first, int last)
{
    QVector<QPersistentModelIndexData *> persistent_moved = persistent.moved.pop();
    int count = (last - first) + 1; // it is important to only use the delta, because the change could be nested
    for (QVector<QPersistentModelIndexData *>::const_iterator it = persistent_moved.constBegin();
         it != persistent_moved.constEnd(); ++it) {
        QPersistentModelIndexData *data = *it;
        QModelIndex old = data->index;
        persistent.indexes.erase(persistent.indexes.find(old));
        data->index = q_func()->index(old.row() + count, old.column(), parent);
        if (data->index.isValid()) {
            persistent.insertMultiAtEnd(data->index, data);
        } else {
            qWarning() << "QAbstractItemModel::endInsertRows:  Invalid index (" << old.row() + count << ',' << old.column() << ") in model" << q_func();
        }
    }
}

void QAbstractItemModelPrivate::itemsAboutToBeMoved(const QModelIndex &srcParent, int srcFirst, int srcLast, const QModelIndex &destinationParent, int destinationChild, Qt::Orientation orientation)
{
    QVector<QPersistentModelIndexData *> persistent_moved_explicitly;
    QVector<QPersistentModelIndexData *> persistent_moved_in_source;
    QVector<QPersistentModelIndexData *> persistent_moved_in_destination;

    QHash<QModelIndex, QPersistentModelIndexData *>::const_iterator it;
    const QHash<QModelIndex, QPersistentModelIndexData *>::const_iterator begin = persistent.indexes.constBegin();
    const QHash<QModelIndex, QPersistentModelIndexData *>::const_iterator end = persistent.indexes.constEnd();

    const bool sameParent = (srcParent == destinationParent);
    const bool movingUp = (srcFirst > destinationChild);

    for ( it = begin; it != end; ++it) {
        QPersistentModelIndexData *data = *it;
        const QModelIndex &index = data->index;
        const QModelIndex &parent = index.parent();
        const bool isSourceIndex = (parent == srcParent);
        const bool isDestinationIndex = (parent == destinationParent);

        int childPosition;
        if (orientation == Qt::Vertical)
            childPosition = index.row();
        else
            childPosition = index.column();

        if (!index.isValid() || !(isSourceIndex || isDestinationIndex ) )
            continue;

        if (!sameParent && isDestinationIndex) {
            if (childPosition >= destinationChild)
                persistent_moved_in_destination.append(data);
            continue;
        }

        if (sameParent && movingUp && childPosition < destinationChild)
            continue;

        if (sameParent && !movingUp && childPosition < srcFirst )
            continue;

        if (!sameParent && childPosition < srcFirst)
            continue;

        if (sameParent && (childPosition > srcLast) && (childPosition >= destinationChild ))
            continue;

        if ((childPosition <= srcLast) && (childPosition >= srcFirst)) {
            persistent_moved_explicitly.append(data);
        } else {
            persistent_moved_in_source.append(data);
        }
    }
    persistent.moved.push(persistent_moved_explicitly);
    persistent.moved.push(persistent_moved_in_source);
    persistent.moved.push(persistent_moved_in_destination);
}

/*!
  \internal

  Moves persistent indexes \a indexes by amount \a change. The change will be either a change in row value or a change in
  column value depending on the value of \a orientation. The indexes may also be moved to a different parent if \a parent
  differs from the existing parent for the index.
*/
void QAbstractItemModelPrivate::movePersistentIndexes(QVector<QPersistentModelIndexData *> indexes, int change, const QModelIndex &parent, Qt::Orientation orientation)
{
    QVector<QPersistentModelIndexData *>::const_iterator it;
    const QVector<QPersistentModelIndexData *>::const_iterator begin = indexes.constBegin();
    const QVector<QPersistentModelIndexData *>::const_iterator end = indexes.constEnd();

    for (it = begin; it != end; ++it)
    {
        QPersistentModelIndexData *data = *it;

        int row = data->index.row();
        int column = data->index.column();

        if (Qt::Vertical == orientation)
            row += change;
        else
            column += change;

        persistent.indexes.erase(persistent.indexes.find(data->index));
        data->index = q_func()->index(row, column, parent);
        if (data->index.isValid()) {
            persistent.insertMultiAtEnd(data->index, data);
        } else {
            qWarning() << "QAbstractItemModel::endMoveRows:  Invalid index (" << row << "," << column << ") in model" << q_func();
        }
    }
}

void QAbstractItemModelPrivate::itemsMoved(const QModelIndex &sourceParent, int sourceFirst, int sourceLast, const QModelIndex &destinationParent, int destinationChild, Qt::Orientation orientation)
{
    QVector<QPersistentModelIndexData *> moved_in_destination = persistent.moved.pop();
    QVector<QPersistentModelIndexData *> moved_in_source = persistent.moved.pop();
    QVector<QPersistentModelIndexData *> moved_explicitly = persistent.moved.pop();

    const bool sameParent = (sourceParent == destinationParent);
    const bool movingUp = (sourceFirst > destinationChild);

    const int explicit_change = (!sameParent || movingUp) ? destinationChild - sourceFirst : destinationChild - sourceLast - 1 ;
    const int source_change = (!sameParent || !movingUp) ? -1*(sourceLast - sourceFirst + 1) : sourceLast - sourceFirst + 1 ;
    const int destination_change = sourceLast - sourceFirst + 1;

    movePersistentIndexes(moved_explicitly, explicit_change, destinationParent, orientation);
    movePersistentIndexes(moved_in_source, source_change, sourceParent, orientation);
    movePersistentIndexes(moved_in_destination, destination_change, destinationParent, orientation);
}

void QAbstractItemModelPrivate::rowsAboutToBeRemoved(const QModelIndex &parent,
                                                     int first, int last)
{
    QVector<QPersistentModelIndexData *>  persistent_moved;
    QVector<QPersistentModelIndexData *>  persistent_invalidated;
    // find the persistent indexes that are affected by the change, either by being in the removed subtree
    // or by being on the same level and below the removed rows
    for (QHash<QModelIndex, QPersistentModelIndexData *>::const_iterator it = persistent.indexes.constBegin();
         it != persistent.indexes.constEnd(); ++it) {
        QPersistentModelIndexData *data = *it;
        bool level_changed = false;
        QModelIndex current = data->index;
        while (current.isValid()) {
            QModelIndex current_parent = current.parent();
            if (current_parent == parent) { // on the same level as the change
                if (!level_changed && current.row() > last) // below the removed rows
                    persistent_moved.append(data);
                else if (current.row() <= last && current.row() >= first) // in the removed subtree
                    persistent_invalidated.append(data);
                break;
            }
            current = current_parent;
            level_changed = true;
        }
    }

    persistent.moved.push(persistent_moved);
    persistent.invalidated.push(persistent_invalidated);
}

void QAbstractItemModelPrivate::rowsRemoved(const QModelIndex &parent,
                                            int first, int last)
{
    QVector<QPersistentModelIndexData *> persistent_moved = persistent.moved.pop();
    int count = (last - first) + 1; // it is important to only use the delta, because the change could be nested
    for (QVector<QPersistentModelIndexData *>::const_iterator it = persistent_moved.constBegin();
         it != persistent_moved.constEnd(); ++it) {
        QPersistentModelIndexData *data = *it;
        QModelIndex old = data->index;
        persistent.indexes.erase(persistent.indexes.find(old));
        data->index = q_func()->index(old.row() - count, old.column(), parent);
        if (data->index.isValid()) {
            persistent.insertMultiAtEnd(data->index, data);
        } else {
            qWarning() << "QAbstractItemModel::endRemoveRows:  Invalid index (" << old.row() - count << ',' << old.column() << ") in model" << q_func();
        }
    }
    QVector<QPersistentModelIndexData *> persistent_invalidated = persistent.invalidated.pop();
    for (QVector<QPersistentModelIndexData *>::const_iterator it = persistent_invalidated.constBegin();
         it != persistent_invalidated.constEnd(); ++it) {
        QPersistentModelIndexData *data = *it;
        persistent.indexes.erase(persistent.indexes.find(data->index));
        data->index = QModelIndex();
        data->model = 0;
    }
}

void QAbstractItemModelPrivate::columnsAboutToBeInserted(const QModelIndex &parent,
                                                         int first, int last)
{
    Q_Q(QAbstractItemModel);
    Q_UNUSED(last);
    QVector<QPersistentModelIndexData *> persistent_moved;
    if (first < q->columnCount(parent)) {
        for (QHash<QModelIndex, QPersistentModelIndexData *>::const_iterator it = persistent.indexes.constBegin();
             it != persistent.indexes.constEnd(); ++it) {
            QPersistentModelIndexData *data = *it;
            const QModelIndex &index = data->index;
            if (index.column() >= first && index.isValid() && index.parent() == parent)
                persistent_moved.append(data);
        }
    }
    persistent.moved.push(persistent_moved);
}

void QAbstractItemModelPrivate::columnsInserted(const QModelIndex &parent,
                                                int first, int last)
{
    QVector<QPersistentModelIndexData *> persistent_moved = persistent.moved.pop();
    int count = (last - first) + 1; // it is important to only use the delta, because the change could be nested
    for (QVector<QPersistentModelIndexData *>::const_iterator it = persistent_moved.constBegin();
         it != persistent_moved.constEnd(); ++it) {
        QPersistentModelIndexData *data = *it;
        QModelIndex old = data->index;
        persistent.indexes.erase(persistent.indexes.find(old));
        data->index = q_func()->index(old.row(), old.column() + count, parent);
        if (data->index.isValid()) {
            persistent.insertMultiAtEnd(data->index, data);
        } else {
            qWarning() << "QAbstractItemModel::endInsertColumns:  Invalid index (" << old.row() << ',' << old.column() + count << ") in model" << q_func();
        }
     }
}

void QAbstractItemModelPrivate::columnsAboutToBeRemoved(const QModelIndex &parent,
                                                        int first, int last)
{
    QVector<QPersistentModelIndexData *> persistent_moved;
    QVector<QPersistentModelIndexData *> persistent_invalidated;
    // find the persistent indexes that are affected by the change, either by being in the removed subtree
    // or by being on the same level and to the right of the removed columns
    for (QHash<QModelIndex, QPersistentModelIndexData *>::const_iterator it = persistent.indexes.constBegin();
         it != persistent.indexes.constEnd(); ++it) {
        QPersistentModelIndexData *data = *it;
        bool level_changed = false;
        QModelIndex current = data->index;
        while (current.isValid()) {
            QModelIndex current_parent = current.parent();
            if (current_parent == parent) { // on the same level as the change
                if (!level_changed && current.column() > last) // right of the removed columns
                    persistent_moved.append(data);
                else if (current.column() <= last && current.column() >= first) // in the removed subtree
                    persistent_invalidated.append(data);
                break;
            }
            current = current_parent;
            level_changed = true;
        }
    }

    persistent.moved.push(persistent_moved);
    persistent.invalidated.push(persistent_invalidated);

}

void QAbstractItemModelPrivate::columnsRemoved(const QModelIndex &parent,
                                               int first, int last)
{
    QVector<QPersistentModelIndexData *> persistent_moved = persistent.moved.pop();
    int count = (last - first) + 1; // it is important to only use the delta, because the change could be nested
    for (QVector<QPersistentModelIndexData *>::const_iterator it = persistent_moved.constBegin();
         it != persistent_moved.constEnd(); ++it) {
        QPersistentModelIndexData *data = *it;
        QModelIndex old = data->index;
        persistent.indexes.erase(persistent.indexes.find(old));
        data->index = q_func()->index(old.row(), old.column() - count, parent);
        if (data->index.isValid()) {
            persistent.insertMultiAtEnd(data->index, data);
        } else {
            qWarning() << "QAbstractItemModel::endRemoveColumns:  Invalid index (" << old.row() << ',' << old.column() - count << ") in model" << q_func();
        }
    }
    QVector<QPersistentModelIndexData *> persistent_invalidated = persistent.invalidated.pop();
    for (QVector<QPersistentModelIndexData *>::const_iterator it = persistent_invalidated.constBegin();
         it != persistent_invalidated.constEnd(); ++it) {
        QPersistentModelIndexData *data = *it;
        persistent.indexes.erase(persistent.indexes.find(data->index));
        data->index = QModelIndex();
        data->model = 0;
    }
}

/*!
    \class QModelIndex

    \brief The QModelIndex class is used to locate data in a data model.

    \ingroup model-view


    This class is used as an index into item models derived from
    QAbstractItemModel. The index is used by item views, delegates, and
    selection models to locate an item in the model.

    New QModelIndex objects are created by the model using the
    QAbstractItemModel::createIndex() function. An \e invalid model index can
    be constructed with the QModelIndex constructor. Invalid indexes are often
    used as parent indexes when referring to top-level items in a model.

    Model indexes refer to items in models, and contain all the information
    required to specify their locations in those models. Each index is located
    in a given row and column, and may have a parent index; use row(),
    column(), and parent() to obtain this information. Each top-level item in a
    model is represented by a model index that does not have a parent index -
    in this case, parent() will return an invalid model index, equivalent to an
    index constructed with the zero argument form of the QModelIndex()
    constructor.

    To obtain a model index that refers to an existing item in a model, call
    QAbstractItemModel::index() with the required row and column values, and
    the model index of the parent. When referring to top-level items in a
    model, supply QModelIndex() as the parent index.

    The model() function returns the model that the index references as a
    QAbstractItemModel. The child() function is used to examine items held
    under the index in the model. The sibling() function allows you to traverse
    items in the model on the same level as the index.

    \note Model indexes should be used immediately and then discarded. You
    should not rely on indexes to remain valid after calling model functions
    that change the structure of the model or delete items. If you need to
    keep a model index over time use a QPersistentModelIndex.

    \sa {Model/View Programming}, QPersistentModelIndex, QAbstractItemModel
*/

/*!
    \fn QModelIndex::QModelIndex()

    Creates a new empty model index. This type of model index is used to
    indicate that the position in the model is invalid.

    \sa isValid() QAbstractItemModel
*/

/*!
    \fn QModelIndex::QModelIndex(int row, int column, void *data, const QAbstractItemModel *model)

    \internal

    Creates a new model index at the given \a row and \a column,
    pointing to some \a data.
*/

/*!
    \fn QModelIndex::QModelIndex(const QModelIndex &other)

    Creates a new model index that is a copy of the \a other model
    index.
*/

/*!
    \fn QModelIndex::~QModelIndex()

    Destroys the model index.
*/

/*!
    \fn int QModelIndex::row() const

    Returns the row this model index refers to.
*/


/*!
    \fn int QModelIndex::column() const

    Returns the column this model index refers to.
*/


/*!
    \fn void *QModelIndex::internalPointer() const

    Returns a \c{void} \c{*} pointer used by the model to associate
    the index with the internal data structure.

    \sa QAbstractItemModel::createIndex()
*/

/*!
    \fn void *QModelIndex::internalId() const

    Returns a \c{qint64} used by the model to associate
    the index with the internal data structure.

    \sa QAbstractItemModel::createIndex()
*/

/*!
    \fn bool QModelIndex::isValid() const

    Returns true if this model index is valid; otherwise returns false.

    A valid index belongs to a model, and has non-negative row and column
    numbers.

    \sa model(), row(), column()
*/

/*!
    \fn const QAbstractItemModel *QModelIndex::model() const

    Returns a pointer to the model containing the item that this index
    refers to.

    A const pointer to the model is returned because calls to non-const
    functions of the model might invalidate the model index and possibly
    crash your application.
*/

/*!
    \fn QModelIndex QModelIndex::sibling(int row, int column) const

    Returns the sibling at \a row and \a column. If there is no sibling at this
    position, an invalid QModelIndex is returned.

    \sa parent(), child()
*/

/*!
    \fn QModelIndex QModelIndex::child(int row, int column) const

    Returns the child of the model index that is stored in the given \a row and
    \a column.

    \sa parent(), sibling()
*/

/*!
    \fn QVariant QModelIndex::data(int role) const

    Returns the data for the given \a role for the item referred to by the
    index.
*/

/*!
    \fn Qt::ItemFlags QModelIndex::flags() const
    \since 4.2

    Returns the flags for the item referred to by the index.
*/

/*!
    \fn bool QModelIndex::operator==(const QModelIndex &other) const

    Returns true if this model index refers to the same location as the
    \a other model index; otherwise returns false.

    All values in the model index are used when comparing with another model
    index.
*/


/*!
    \fn bool QModelIndex::operator!=(const QModelIndex &other) const

    Returns true if this model index does not refer to the same location as
    the \a other model index; otherwise returns false.
*/


/*!
    \fn QModelIndex QModelIndex::parent() const

    Returns the parent of the model index, or QModelIndex() if it has no
    parent.

    \sa child(), sibling(), model()
*/

/*!
    \class QAbstractItemModel

    \brief The QAbstractItemModel class provides the abstract interface for
    item model classes.

    \ingroup model-view


    The QAbstractItemModel class defines the standard interface that item
    models must use to be able to interoperate with other components in the
    model/view architecture. It is not supposed to be instantiated directly.
    Instead, you should subclass it to create new models.

    The QAbstractItemModel class is one of the \l{Model/View Classes}
    and is part of Qt's \l{Model/View Programming}{model/view framework}.

    If you need a model to use with a QListView or a QTableView, you should
    consider subclassing QAbstractListModel or QAbstractTableModel instead of
    this class.

    The underlying data model is exposed to views and delegates as a hierarchy
    of tables. If you do not make use of the hierarchy, then the model is a
    simple table of rows and columns. Each item has a unique index specified by
    a QModelIndex.

    \image modelindex-no-parent.png

    Every item of data that can be accessed via a model has an associated model
    index. You can obtain this model index using the index() function. Each
    index may have a sibling() index; child items have a parent() index.

    Each item has a number of data elements associated with it and they can be
    retrieved by specifying a role (see \l Qt::ItemDataRole) to the model's
    data() function. Data for all available roles can be obtained at the same
    time using the itemData() function.

    Data for each role is set using a particular \l Qt::ItemDataRole. Data for
    individual roles are set individually with setData(), or they can be set
    for all roles with setItemData().

    Items can be queried with flags() (see \l Qt::ItemFlag) to see if they can
    be selected, dragged, or manipulated in other ways.

    If an item has child objects, hasChildren() returns true for the
    corresponding index.

    The model has a rowCount() and a columnCount() for each level of the
    hierarchy. Rows and columns can be inserted and removed with insertRows(),
    insertColumns(), removeRows(), and removeColumns().

    The model emits signals to indicate changes. For example, dataChanged() is
    emitted whenever items of data made available by the model are changed.
    Changes to the headers supplied by the model cause headerDataChanged() to
    be emitted. If the structure of the underlying data changes, the model can
    emit layoutChanged() to indicate to any attached views that they should
    redisplay any items shown, taking the new structure into account.

    The items available through the model can be searched for particular data
    using the match() function.

    To sort the model, you can use sort().


    \section1 Subclassing

    \note Some general guidelines for subclassing models are available in the
    \l{Model Subclassing Reference}.

    When subclassing QAbstractItemModel, at the very least you must implement
    index(), parent(), rowCount(), columnCount(), and data(). These functions
    are used in all read-only models, and form the basis of editable models.

    You can also reimplement hasChildren() to provide special behavior for
    models where the implementation of rowCount() is expensive. This makes it
    possible for models to restrict the amount of data requested by views, and
    can be used as a way to implement lazy population of model data.

    To enable editing in your model, you must also implement setData(), and
    reimplement flags() to ensure that \c ItemIsEditable is returned.  You can
    also reimplement headerData() and setHeaderData() to control the way the
    headers for your model are presented.

    The dataChanged() and headerDataChanged() signals must be emitted
    explicitly when reimplementing the setData() and setHeaderData() functions,
    respectively.

    Custom models need to create model indexes for other components to use. To
    do this, call createIndex() with suitable row and column numbers for the
    item, and an identifier for it, either as a pointer or as an integer value.
    The combination of these values must be unique for each item. Custom models
    typically use these unique identifiers in other reimplemented functions to
    retrieve item data and access information about the item's parents and
    children. See the \l{Simple Tree Model Example} for more information about
    unique identifiers.

    It is not necessary to support every role defined in Qt::ItemDataRole.
    Depending on the type of data contained within a model, it may only be
    useful to implement the data() function to return valid information for
    some of the more common roles. Most models provide at least a textual
    representation of item data for the Qt::DisplayRole, and well-behaved
    models should also provide valid information for the Qt::ToolTipRole and
    Qt::WhatsThisRole. Supporting these roles enables models to be used with
    standard Qt views. However, for some models that handle highly-specialized
    data, it may be appropriate to provide data only for user-defined roles.

    Models that provide interfaces to resizable data structures can provide
    implementations of insertRows(), removeRows(), insertColumns(),and
    removeColumns(). When implementing these functions, it is important to
    notify any connected views about changes to the model's dimensions both
    \e before and \e after they occur:

    \list
        \o An insertRows() implementation must call beginInsertRows() \e before
           inserting new rows into the data structure, and endInsertRows()
           \e{immediately afterwards}.
        \o An insertColumns() implementation must call beginInsertColumns()
           \e before inserting new columns into the data structure, and
           endInsertColumns() \e{immediately afterwards}.
        \o A removeRows() implementation must call beginRemoveRows() \e before
           the rows are removed from the data structure, and endRemoveRows()
           \e{immediately afterwards}.
        \o A removeColumns() implementation must call beginRemoveColumns()
           \e before the columns are removed from the data structure, and
           endRemoveColumns() \e{immediately afterwards}.
    \endlist

    The \e private signals that these functions emit give attached components
    the chance to take action before any data becomes unavailable. The
    encapsulation of the insert and remove operations with these begin and end
    functions also enables the model to manage \l{QPersistentModelIndex}
    {persistent model indexes} correctly. \bold{If you want selections to be
    handled properly, you must ensure that you call these functions.} If you
    insert or remove an item with children, you do not need to call these
    functions for the child items. In other words, the parent item will take
    care of its child items.

    To create models that populate incrementally, you can reimplement
    fetchMore() and canFetchMore(). If the reimplementation of fetchMore() adds
    rows to the model, \l{QAbstractItemModel::}{beginInsertRows()} and
    \l{QAbstractItemModel::}{endInsertRows()} must be called.

    \sa {Model Classes}, {Model Subclassing Reference}, QModelIndex,
        QAbstractItemView, {Using Drag and Drop with Item Views},
        {Simple DOM Model Example}, {Simple Tree Model Example},
        {Editable Tree Model Example}, {Fetch More Example}
*/

/*!
    \fn QModelIndex QAbstractItemModel::index(int row, int column, const QModelIndex &parent) const = 0

    Returns the index of the item in the model specified by the given \a row,
    \a column and \a parent index.

    When reimplementing this function in a subclass, call createIndex() to
    generate model indexes that other components can use to refer to items in
    your model.

    \sa createIndex()
*/

/*!
    \fn bool QAbstractItemModel::insertColumn(int column, const QModelIndex &parent)

    Inserts a single column before the given \a column in the child items of
    the \a parent specified.

    Returns true if the column is inserted; otherwise returns false.

    \sa insertColumns() insertRow() removeColumn()
*/

/*!
    \fn bool QAbstractItemModel::insertRow(int row, const QModelIndex &parent)

    \note The base class implementation of this function does nothing and
    returns false.

    Inserts a single row before the given \a row in the child items of the
    \a parent specified.

    Returns true if the row is inserted; otherwise returns false.

    \sa insertRows() insertColumn() removeRow()
*/

/*!
    \fn QObject *QAbstractItemModel::parent() const
    \internal
*/

/*!
    \fn QModelIndex QAbstractItemModel::parent(const QModelIndex &index) const = 0

    Returns the parent of the model item with the given \a index. If the item
    has no parent, an invalid QModelIndex is returned.

    A common convention used in models that expose tree data structures is that
    only items in the first column have children. For that case, when
    reimplementing this function in a subclass the column of the returned
    QModelIndex would be 0.

    When reimplementing this function in a subclass, be careful to avoid
    calling QModelIndex member functions, such as QModelIndex::parent(), since
    indexes belonging to your model will simply call your implementation,
    leading to infinite recursion.

    \sa createIndex()
*/

/*!
    \fn bool QAbstractItemModel::removeColumn(int column, const QModelIndex &parent)

    Removes the given \a column from the child items of the \a parent
    specified.

    Returns true if the column is removed; otherwise returns false.

    \sa removeColumns(), removeRow(), insertColumn()
*/

/*!
    \fn bool QAbstractItemModel::removeRow(int row, const QModelIndex &parent)

    Removes the given \a row from the child items of the \a parent specified.

    Returns true if the row is removed; otherwise returns false.

    This is a convenience function that calls removeRows(). The
    QAbstractItemModel implementation of removeRows() does nothing.

    \sa removeRows(), removeColumn(), insertRow()
*/

/*!
    \fn void QAbstractItemModel::headerDataChanged(Qt::Orientation orientation, int first, int last)

    This signal is emitted whenever a header is changed. The \a orientation
    indicates whether the horizontal or vertical header has changed. The
    sections in the header from the \a first to the \a last need to be updated.

    When reimplementing the setHeaderData() function, this signal must be
    emitted explicitly.

    If you are changing the number of columns or rows you do not need to emit
    this signal, but use the begin/end functions (refer to the section on
    subclassing in the QAbstractItemModel class description for details).

    \sa headerData(), setHeaderData(), dataChanged()
*/

/*!
    \fn void QAbstractItemModel::layoutAboutToBeChanged()
    \since 4.2

    This signal is emitted just before the layout of a model is changed.
    Components connected to this signal use it to adapt to changes in the
    model's layout.

    Subclasses should update any persistent model indexes after emitting
    layoutAboutToBeChanged().

    \sa layoutChanged(), changePersistentIndex()
*/

/*!
    \fn void QAbstractItemModel::layoutChanged()

    This signal is emitted whenever the layout of items exposed by the model
    has changed; for example, when the model has been sorted. When this signal
    is received by a view, it should update the layout of items to reflect this
    change.

    When subclassing QAbstractItemModel or QAbstractProxyModel, ensure that you
    emit layoutAboutToBeChanged() before changing the order of items or
    altering the structure of the data you expose to views, and emit
    layoutChanged() after changing the layout.

    Subclasses should update any persistent model indexes before emitting
    layoutChanged(). In other words, when the structure changes:

    \list
        \o  Call beginLayoutChanged()
        \o  Remember the QModelIndex that will change
        \o  Update your internal data
        \o  Call changePersistentIndex()
        \o  Call endLayoutChanged()
    \endlist


    \sa layoutAboutToBeChanged(), dataChanged(), headerDataChanged(), modelReset(),
        changePersistentIndex()
*/

/*!
    Constructs an abstract item model with the given \a parent.
*/
QAbstractItemModel::QAbstractItemModel(QObject *parent)
    : QObject(*new QAbstractItemModelPrivate, parent)
{
}

/*!
  \internal
*/
QAbstractItemModel::QAbstractItemModel(QAbstractItemModelPrivate &dd, QObject *parent)
    : QObject(dd, parent)
{
}

/*!
    Destroys the abstract item model.
*/
QAbstractItemModel::~QAbstractItemModel()
{
    d_func()->invalidatePersistentIndexes();
}

/*!
    \fn QModelIndex QAbstractItemModel::sibling(int row, int column, const QModelIndex &index) const

    Returns the sibling at \a row and \a column for the item at \a index, or an
    invalid QModelIndex if there is no sibling at that location.

    sibling() is just a convenience function that finds the item's parent, and
    uses it to retrieve the index of the child item in the specified \a row and
    \a column.

    \sa index(), QModelIndex::row(), QModelIndex::column()
*/


/*!
    \fn int QAbstractItemModel::rowCount(const QModelIndex &parent) const

    Returns the number of rows under the given \a parent. When the parent is
    valid it means that rowCount is returning the number of children of parent.

    \note When implementing a table based model, rowCount() should return 0
    when the parent is valid.

    \sa columnCount()
*/

/*!
    \fn int QAbstractItemModel::columnCount(const QModelIndex &parent) const

    Returns the number of columns for the children of the given \a parent.

    In most subclasses, the number of columns is independent of the \a parent.

    For example:

    \snippet examples/itemviews/simpledommodel/dommodel.cpp 2

    \note When implementing a table based model, columnCount() should return 0
    when the parent is valid.

    \sa rowCount()
*/

/*!
    \fn void QAbstractItemModel::dataChanged(const QModelIndex &topLeft, const QModelIndex &bottomRight)

    This signal is emitted whenever the data in an existing item changes.

    If the items are of the same parent, the affected ones are those between
    \a topLeft and \a bottomRight inclusive. If the items do not have the same
    parent, the behavior is undefined.

    When reimplementing the setData() function, this signal must be emitted
    explicitly.

    \sa headerDataChanged(), setData(), layoutChanged()
*/

/*!
    \fn void QAbstractItemModel::rowsInserted(const QModelIndex &parent, int start, int end)

    This signal is emitted after rows have been inserted into the
    model. The new items are those between \a start and \a end
    inclusive, under the given \a parent item.

    \note Components connected to this signal use it to adapt to changes in the
    model's dimensions. It can only be emitted by the QAbstractItemModel
    implementation, and cannot be explicitly emitted in subclass code.

    \sa insertRows(), beginInsertRows()
*/

/*!
    \fn void QAbstractItemModel::rowsAboutToBeInserted(const QModelIndex &parent, int start, int end)

    This signal is emitted just before rows are inserted into the model. The
    new items will be positioned between \a start and \a end inclusive, under
    the given \a parent item.

    \note Components connected to this signal use it to adapt to changes
    in the model's dimensions. It can only be emitted by the QAbstractItemModel
    implementation, and cannot be explicitly emitted in subclass code.

    \sa insertRows(), beginInsertRows()
*/

/*!
    \fn void QAbstractItemModel::rowsRemoved(const QModelIndex &parent, int start, int end)

    This signal is emitted after rows have been removed from the model. The
    removed items are those between \a start and \a end inclusive, under the
    given \a parent item.

    \note Components connected to this signal use it to adapt to changes
    in the model's dimensions. It can only be emitted by the QAbstractItemModel
    implementation, and cannot be explicitly emitted in subclass code.

    \sa removeRows(), beginRemoveRows()
*/

/*!
    \fn void QAbstractItemModel::rowsAboutToBeRemoved(const QModelIndex &parent, int start, int end)

    This signal is emitted just before rows are removed from the model. The
    items that will be removed are those between \a start and \a end inclusive,
    under the given \a parent item.

    \note Components connected to this signal use it to adapt to changes
    in the model's dimensions. It can only be emitted by the QAbstractItemModel
    implementation, and cannot be explicitly emitted in subclass code.

    \sa removeRows(), beginRemoveRows()
*/

/*!
    \fn void QAbstractItemModel::rowsMoved(const QModelIndex &sourceParent, int sourceStart, int sourceEnd, const QModelIndex &destinationParent, int destinationRow)
    \since 4.6

    This signal is emitted after rows have been moved within the
    model. The items between \a sourceStart and \a sourceEnd
    inclusive, under the given \a sourceParent item have been moved to \a destinationParent
    starting at the row \a destinationRow.

    \bold{Note:} Components connected to this signal use it to adapt to changes
    in the model's dimensions. It can only be emitted by the QAbstractItemModel
    implementation, and cannot be explicitly emitted in subclass code.

    \sa beginMoveRows()
*/

/*!
    \fn void QAbstractItemModel::rowsAboutToBeMoved(const QModelIndex &sourceParent, int sourceStart, int sourceEnd, const QModelIndex &destinationParent, int destinationRow)
    \since 4.6

    This signal is emitted just before rows are moved within the
    model. The items that will be moved are those between \a sourceStart and \a sourceEnd
    inclusive, under the given \a sourceParent item. They will be moved to \a destinationParent
    starting at the row \a destinationRow.

    \bold{Note:} Components connected to this signal use it to adapt to changes
    in the model's dimensions. It can only be emitted by the QAbstractItemModel
    implementation, and cannot be explicitly emitted in subclass code.

    \sa beginMoveRows()
*/

/*!
    \fn void QAbstractItemModel::columnsMoved(const QModelIndex &sourceParent, int sourceStart, int sourceEnd, const QModelIndex &destinationParent, int destinationColumn)
    \since 4.6

    This signal is emitted after columns have been moved within the
    model. The items between \a sourceStart and \a sourceEnd
    inclusive, under the given \a sourceParent item have been moved to \a destinationParent
    starting at the column \a destinationColumn.

    \bold{Note:} Components connected to this signal use it to adapt to changes
    in the model's dimensions. It can only be emitted by the QAbstractItemModel
    implementation, and cannot be explicitly emitted in subclass code.

    \sa beginMoveRows()
*/

/*!
    \fn void QAbstractItemModel::columnsAboutToBeMoved(const QModelIndex &sourceParent, int sourceStart, int sourceEnd, const QModelIndex &destinationParent, int destinationColumn)
    \since 4.6

    This signal is emitted just before columns are moved within the
    model. The items that will be moved are those between \a sourceStart and \a sourceEnd
    inclusive, under the given \a sourceParent item. They will be moved to \a destinationParent
    starting at the column \a destinationColumn.

    \bold{Note:} Components connected to this signal use it to adapt to changes
    in the model's dimensions. It can only be emitted by the QAbstractItemModel
    implementation, and cannot be explicitly emitted in subclass code.

    \sa beginMoveRows()
*/

/*!
    \fn void QAbstractItemModel::columnsInserted(const QModelIndex &parent, int start, int end)

    This signal is emitted after columns have been inserted into the model. The
    new items are those between \a start and \a end inclusive, under the given
    \a parent item.

    \note Components connected to this signal use it to adapt to changes in the
    model's dimensions. It can only be emitted by the QAbstractItemModel
    implementation, and cannot be explicitly emitted in subclass code.

    \sa insertColumns(), beginInsertColumns()
*/

/*!
    \fn void QAbstractItemModel::columnsAboutToBeInserted(const QModelIndex &parent, int start, int end)

    This signal is emitted just before columns are inserted into the model. The
    new items will be positioned between \a start and \a end inclusive, under
    the given \a parent item.

    \note Components connected to this signal use it to adapt to changes in the
    model's dimensions. It can only be emitted by the QAbstractItemModel
    implementation, and cannot be explicitly emitted in subclass code.

    \sa insertColumns(), beginInsertColumns()
*/

/*!
    \fn void QAbstractItemModel::columnsRemoved(const QModelIndex &parent, int start, int end)

    This signal is emitted after columns have been removed from the model.
    The removed items are those between \a start and \a end inclusive,
    under the given \a parent item.

    \note Components connected to this signal use it to adapt to changes in
    the model's dimensions. It can only be emitted by the QAbstractItemModel
    implementation, and cannot be explicitly emitted in subclass code.

    \sa removeColumns(), beginRemoveColumns()
*/

/*!
    \fn void QAbstractItemModel::columnsAboutToBeRemoved(const QModelIndex &parent, int start, int end)

    This signal is emitted just before columns are removed from the model. The
    items to be removed are those between \a start and \a end inclusive, under
    the given \a parent item.

    \note Components connected to this signal use it to adapt to changes in the
    model's dimensions. It can only be emitted by the QAbstractItemModel
    implementation, and cannot be explicitly emitted in subclass code.

    \sa removeColumns(), beginRemoveColumns()
*/

/*!
    Returns true if the model returns a valid QModelIndex for \a row and
    \a column with \a parent, otherwise returns false.
*/
bool QAbstractItemModel::hasIndex(int row, int column, const QModelIndex &parent) const
{
    if (row < 0 || column < 0)
        return false;
    return row < rowCount(parent) && column < columnCount(parent);
}


/*!
    Returns true if \a parent has any children; otherwise returns false.

    Use rowCount() on the parent to find out the number of children.

    \sa parent() index()
*/
bool QAbstractItemModel::hasChildren(const QModelIndex &parent) const
{
    return (rowCount(parent) > 0) && (columnCount(parent) > 0);
}


/*!
    Returns a map with values for all predefined roles in the model for the
    item at the given \a index.

    Reimplement this function if you want to extend the default behavior of
    this function to include custom roles in the map.

    \sa Qt::ItemDataRole, data()
*/
QMap<int, QVariant> QAbstractItemModel::itemData(const QModelIndex &index) const
{
    QMap<int, QVariant> roles;
    for (int i = 0; i < Qt::UserRole; ++i) {
        QVariant variantData = data(index, i);
        if (variantData.isValid())
            roles.insert(i, variantData);
    }
    return roles;
}

/*!
    Sets the \a role data for the item at \a index to \a value.

    Returns true if successful; otherwise returns false.

    The dataChanged() signal should be emitted if the data was successfully
    set.

    The base class implementation returns false. This function and data() must
    be reimplemented for editable models.

    \sa Qt::ItemDataRole, data(), itemData()
*/
bool QAbstractItemModel::setData(const QModelIndex &index, const QVariant &value, int role)
{
    Q_UNUSED(index);
    Q_UNUSED(value);
    Q_UNUSED(role);
    return false;
}

/*!
    \fn QVariant QAbstractItemModel::data(const QModelIndex &index, int role) const = 0

    Returns the data stored under the given \a role for the item referred to
    by the \a index.

    \note If you do not have a value to return, return an \bold invalid
    QVariant instead of returning 0.

    \sa Qt::ItemDataRole, setData(), headerData()
*/

/*!
    Sets the role data for the item at \a index to the associated value in
    \a roles, for every Qt::ItemDataRole.

    Returns true if successful; otherwise returns false.

    Roles that are not in \a roles will not be modified.

    \sa setData() data() itemData()
*/
bool QAbstractItemModel::setItemData(const QModelIndex &index, const QMap<int, QVariant> &roles)
{
    bool b = true;
    for (QMap<int, QVariant>::ConstIterator it = roles.begin(); it != roles.end(); ++it)
        b = b && setData(index, it.value(), it.key());
    return b;
}

/*!
    Returns a list of MIME types that can be used to describe a list of model
    indexes.

    \sa mimeData()
*/
QStringList QAbstractItemModel::mimeTypes() const
{
    QStringList types;
    types << QLatin1String("application/x-qabstractitemmodeldatalist");
    return types;
}

/*!
    Returns an object that contains serialized items of data corresponding to
    the list of \a indexes specified. The formats used to describe the encoded
    data is obtained from the mimeTypes() function.

    If the list of indexes is empty, or there are no supported MIME types, 0 is
    returned rather than a serialized empty list.

    \sa mimeTypes(), dropMimeData()
*/
QMimeData *QAbstractItemModel::mimeData(const QModelIndexList &indexes) const
{
    if (indexes.count() <= 0)
        return 0;
    QStringList types = mimeTypes();
    if (types.isEmpty())
        return 0;
    QMimeData *data = new QMimeData();
    QString format = types.at(0);
    QByteArray encoded;
    QDataStream stream(&encoded, QIODevice::WriteOnly);
    encodeData(indexes, stream);
    data->setData(format, encoded);
    return data;
}

/*!
    Handles the \a data supplied by a drag and drop operation that ended with
    the given \a action.

    Returns true if the data and action can be handled by the model; otherwise
    returns false.

    Although the specified \a row, \a column and \a parent indicate the
    location of an item in the model where the operation ended, it is the
    responsibility of the view to provide a suitable location for where the
    data should be inserted.

    For instance, a drop action on an item in a QTreeView can result in new
    items either being inserted as children of the item specified by \a row,
    \a column, and \a parent, or as siblings of the item.

    When row and column are -1 it means that it is up to the model to decide
    where to place the data. This can occur in a tree when data is dropped on
    a parent. Models will usually append the data to the parent in this case.

    \sa supportedDropActions(), {Using Drag and Drop with Item Views}
*/
bool QAbstractItemModel::dropMimeData(const QMimeData *data, Qt::DropAction action,
                                      int row, int column, const QModelIndex &parent)
{
    // check if the action is supported
    if (!data || !(action == Qt::CopyAction || action == Qt::MoveAction))
        return false;
    // check if the format is supported
    QStringList types = mimeTypes();
    if (types.isEmpty())
        return false;
    QString format = types.at(0);
    if (!data->hasFormat(format))
        return false;
    if (row > rowCount(parent))
        row = rowCount(parent);
    if (row == -1)
        row = rowCount(parent);
    if (column == -1)
        column = 0;
    // decode and insert
    QByteArray encoded = data->data(format);
    QDataStream stream(&encoded, QIODevice::ReadOnly);
    return decodeData(row, column, parent, stream);
}

/*!
    \since 4.2

    Returns the drop actions supported by this model.

    The default implementation returns Qt::CopyAction. Reimplement this
    function if you wish to support additional actions. You must also
    reimplement the dropMimeData() function to handle the additional
    operations.

    \sa dropMimeData(), Qt::DropActions, {Using Drag and Drop with Item
    Views}
*/
Qt::DropActions QAbstractItemModel::supportedDropActions() const
{
    return Qt::CopyAction;
}

/*!
    Returns the actions supported by the data in this model.

    The default implementation returns supportedDropActions() unless specific
    values have been set with setSupportedDragActions().

    supportedDragActions() is used by QAbstractItemView::startDrag() as the
    default values when a drag occurs.

    \sa Qt::DropActions, {Using Drag and Drop with Item Views}
*/
Qt::DropActions QAbstractItemModel::supportedDragActions() const
{
    // ### Qt 5: make this virtual or these properties
    Q_D(const QAbstractItemModel);
    if (d->supportedDragActions != -1)
        return d->supportedDragActions;
    return supportedDropActions();
}

/*!
    \since 4.2

    Sets the supported drag \a actions for the items in the model.

    \sa supportedDragActions(), {Using Drag and Drop with Item Views}
*/
void QAbstractItemModel::setSupportedDragActions(Qt::DropActions actions)
{
    Q_D(QAbstractItemModel);
    d->supportedDragActions = actions;
}

/*!
    \note The base class implementation of this function does nothing and
    returns false.

    On models that support this, inserts \a count rows into the model before
    the given \a row. Items in the new row will be children of the item
    represented by the \a parent model index.

    If \a row is 0, the rows are prepended to any existing rows in the parent.

    If \a row is rowCount(), the rows are appended to any existing rows in the
    parent.

    If \a parent has no children, a single column with \a count rows is
    inserted.

    Returns true if the rows were successfully inserted; otherwise returns
    false.

    If you implement your own model, you can reimplement this function if you
    want to support insertions. Alternatively, you can provide your own API for
    altering the data. In either case, you will need to call
    beginInsertRows() and endInsertRows() to notify other components that the
    model has changed.

    \sa insertColumns(), removeRows(), beginInsertRows(), endInsertRows()
*/
bool QAbstractItemModel::insertRows(int, int, const QModelIndex &)
{
    return false;
}

/*!
    On models that support this, inserts \a count new columns into the model
    before the given \a column. The items in each new column will be children
    of the item represented by the \a parent model index.

    If \a column is 0, the columns are prepended to any existing columns.

    If \a column is columnCount(), the columns are appended to any existing
    columns.

    If \a parent has no children, a single row with \a count columns is
    inserted.

    Returns true if the columns were successfully inserted; otherwise returns
    false.

    The base class implementation does nothing and returns false.

    If you implement your own model, you can reimplement this function if you
    want to support insertions. Alternatively, you can provide your own API for
    altering the data.

    \sa insertRows(), removeColumns(), beginInsertColumns(), endInsertColumns()
*/
bool QAbstractItemModel::insertColumns(int, int, const QModelIndex &)
{
    return false;
}

/*!
    On models that support this, removes \a count rows starting with the given
    \a row under parent \a parent from the model.

    Returns true if the rows were successfully removed; otherwise returns
    false.

    The base class implementation does nothing and returns false.

    If you implement your own model, you can reimplement this function if you
    want to support removing. Alternatively, you can provide your own API for
    altering the data.

    \sa removeRow(), removeColumns(), insertColumns(), beginRemoveRows(),
        endRemoveRows()
*/
bool QAbstractItemModel::removeRows(int, int, const QModelIndex &)
{
    return false;
}

/*!
    On models that support this, removes \a count columns starting with the
    given \a column under parent \a parent from the model.

    Returns true if the columns were successfully removed; otherwise returns
    false.

    The base class implementation does nothing and returns false.

    If you implement your own model, you can reimplement this function if you
    want to support removing. Alternatively, you can provide your own API for
    altering the data.

    \sa removeColumn(), removeRows(), insertColumns(), beginRemoveColumns(),
        endRemoveColumns()
*/
bool QAbstractItemModel::removeColumns(int, int, const QModelIndex &)
{
    return false;
}

/*!
    Fetches any available data for the items with the parent specified by the
    \a parent index.

    Reimplement this if you are populating your model incrementally.

    The default implementation does nothing.

    \sa canFetchMore()
*/
void QAbstractItemModel::fetchMore(const QModelIndex &)
{
    // do nothing
}

/*!
    Returns true if there is more data available for \a parent; otherwise
    returns false.

    The default implementation always returns false.

    If canFetchMore() returns true, QAbstractItemView will call fetchMore().
    However, the fetchMore() function is only called when the model is being
    populated incrementally.

    \sa fetchMore()
*/
bool QAbstractItemModel::canFetchMore(const QModelIndex &) const
{
    return false;
}

/*!
    Returns the item flags for the given \a index.

    The base class implementation returns a combination of flags that enables
    the item (\c ItemIsEnabled) and allows it to be selected
    (\c ItemIsSelectable).

    \sa Qt::ItemFlags
*/
Qt::ItemFlags QAbstractItemModel::flags(const QModelIndex &index) const
{
    Q_D(const QAbstractItemModel);
    if (!d->indexValid(index))
        return 0;

    return Qt::ItemIsSelectable|Qt::ItemIsEnabled;
}

/*!
    Sorts the model by \a column in the given \a order.

    The base class implementation does nothing.
*/
void QAbstractItemModel::sort(int column, Qt::SortOrder order)
{
    Q_UNUSED(column);
    Q_UNUSED(order);
    // do nothing
}

/*!
    Returns a model index for the buddy of the item represented by \a index.
    When the user wants to edit an item, the view will call this function to
    check whether another item in the model should be edited instead. Then, the
    view will construct a delegate using the model index returned by the buddy
    item.

    The default implementation of this function has each item as its own buddy.
*/
QModelIndex QAbstractItemModel::buddy(const QModelIndex &index) const
{
    return index;
}

/*!
    Returns a list of indexes for the items in the column of the \a start index
    where data stored under the given \a role matches the specified \a value.
    The way the search is performed is defined by the \a flags given. The list
    that is returned may be empty.

    The search begins from the \a start index, and continues until the number
    of matching data items equals \a hits, the search reaches the last row, or
    the search reaches \a start again - depending on whether \c MatchWrap is
    specified in \a flags. If you want to search for all matching items, use
    \a hits = -1.

    By default, this function will perform a wrapping, string-based comparison
    on all items, searching for items that begin with the search term specified
    by \a value.

    \note The default implementation of this function only searches columns.
    Reimplement this function to include a different search behavior.
*/
QModelIndexList QAbstractItemModel::match(const QModelIndex &start, int role,
                                          const QVariant &value, int hits,
                                          Qt::MatchFlags flags) const
{
    QModelIndexList result;
    uint matchType = flags & 0x0F;
    Qt::CaseSensitivity cs = flags & Qt::MatchCaseSensitive ? Qt::CaseSensitive : Qt::CaseInsensitive;
    bool recurse = flags & Qt::MatchRecursive;
    bool wrap = flags & Qt::MatchWrap;
    bool allHits = (hits == -1);
    QString text; // only convert to a string if it is needed
    QModelIndex p = parent(start);
    int from = start.row();
    int to = rowCount(p);

    // iterates twice if wrapping
    for (int i = 0; (wrap && i < 2) || (!wrap && i < 1); ++i) {
        for (int r = from; (r < to) && (allHits || result.count() < hits); ++r) {
            QModelIndex idx = index(r, start.column(), p);
            if (!idx.isValid())
                 continue;
            QVariant v = data(idx, role);
            // QVariant based matching
            if (matchType == Qt::MatchExactly) {
                if (value == v)
                    result.append(idx);
            } else { // QString based matching
                if (text.isEmpty()) // lazy conversion
                    text = value.toString();
                QString t = v.toString();
                switch (matchType) {
                case Qt::MatchRegExp:
                    if (QRegExp(text, cs).exactMatch(t))
                        result.append(idx);
                    break;
                case Qt::MatchWildcard:
                    if (QRegExp(text, cs, QRegExp::Wildcard).exactMatch(t))
                        result.append(idx);
                    break;
                case Qt::MatchStartsWith:
                    if (t.startsWith(text, cs))
                        result.append(idx);
                    break;
                case Qt::MatchEndsWith:
                    if (t.endsWith(text, cs))
                        result.append(idx);
                    break;
                case Qt::MatchFixedString:
                    if (t.compare(text, cs) == 0)
                        result.append(idx);
                    break;
                case Qt::MatchContains:
                default:
                    if (t.contains(text, cs))
                        result.append(idx);
                }
            }
            if (recurse && hasChildren(idx)) { // search the hierarchy
                result += match(index(0, idx.column(), idx), role,
                                (text.isEmpty() ? value : text),
                                (allHits ? -1 : hits - result.count()), flags);
            }
        }
        // prepare for the next iteration
        from = 0;
        to = start.row();
    }
    return result;
}

/*!
    Returns the row and column span of the item represented by \a index.

    \note Currently, span is not used.
*/

QSize QAbstractItemModel::span(const QModelIndex &) const
{
    return QSize(1, 1);
}

/*!
    \since 4.6

    Sets the model's role names to \a roleNames.

    This function allows mapping of role identifiers to role property names in
    Declarative UI.  This function must be called before the model is used.
    Modifying the role names after the model has been set may result in
    undefined behaviour.

    \sa roleNames()
*/
void QAbstractItemModel::setRoleNames(const QHash<int,QByteArray> &roleNames)
{
    Q_D(QAbstractItemModel);
    d->roleNames = roleNames;
}

/*!
    \since 4.6

    Returns the model's role names.

    \sa setRoleNames()
*/
const QHash<int,QByteArray> &QAbstractItemModel::roleNames() const
{
    Q_D(const QAbstractItemModel);
    return d->roleNames;
}

/*!
    Lets the model know that it should submit cached information to permanent
    storage. This function is typically used for row editing.

    Returns true if there is no error; otherwise returns false.

    \sa revert()
*/

bool QAbstractItemModel::submit()
{
    return true;
}

/*!
    Lets the model know that it should discard cached information. This
    function is typically used for row editing.

    \sa submit()
*/

void QAbstractItemModel::revert()
{
    // do nothing
}

/*!
    Returns the data for the given \a role and \a section in the header with
    the specified \a orientation.

    For horizontal headers, the section number corresponds to the column
    number. Similarly, for vertical headers, the section number corresponds to
    the row number.

    \sa Qt::ItemDataRole, setHeaderData(), QHeaderView
*/

QVariant QAbstractItemModel::headerData(int section, Qt::Orientation orientation, int role) const
{
    Q_UNUSED(orientation);
    if (role == Qt::DisplayRole)
        return section + 1;
    return QVariant();
}

/*!
    Sets the data for the given \a role and \a section in the header with the
    specified \a orientation to the \a value supplied.

    Returns true if the header's data was updated; otherwise returns false.

    When reimplementing this function, the headerDataChanged() signal must be
    emitted explicitly.

    \sa Qt::ItemDataRole, headerData()
*/

bool QAbstractItemModel::setHeaderData(int section, Qt::Orientation orientation,
                                       const QVariant &value, int role)
{
    Q_UNUSED(section);
    Q_UNUSED(orientation);
    Q_UNUSED(value);
    Q_UNUSED(role);
    return false;
}

/*!
    \fn QModelIndex QAbstractItemModel::createIndex(int row, int column, void *ptr) const

    Creates a model index for the given \a row and \a column with the internal
    pointer \a ptr.

    When using a QSortFilterProxyModel, its indexes have their own internal
    pointer. It is not advisable to access this internal pointer outside of the
    model. Use the data() function instead.

    This function provides a consistent interface that model subclasses must
    use to create model indexes.
*/

/*!
    \fn QModelIndex QAbstractItemModel::createIndex(int row, int column, int id) const
    \obsolete

    Use QModelIndex
    QAbstractItemModel::createIndex(int row, int column, quint32 id) instead.
*/

/*!
    \fn QModelIndex QAbstractItemModel::createIndex(int row, int column, quint32 id) const

    Creates a model index for the given \a row and \a column with the internal
    identifier, \a id.

    This function provides a consistent interface that model subclasses must
    use to create model indexes.

    \sa QModelIndex::internalId()
*/

/*!
  \internal
*/
void QAbstractItemModel::encodeData(const QModelIndexList &indexes, QDataStream &stream) const
{
    QModelIndexList::ConstIterator it = indexes.begin();
    for (; it != indexes.end(); ++it)
        stream << (*it).row() << (*it).column() << itemData(*it);
}

/*!
  \internal
 */
bool QAbstractItemModel::decodeData(int row, int column, const QModelIndex &parent,
                                    QDataStream &stream)
{
    int top = INT_MAX;
    int left = INT_MAX;
    int bottom = 0;
    int right = 0;
    QVector<int> rows, columns;
    QVector<QMap<int, QVariant> > data;

    while (!stream.atEnd()) {
        int r, c;
        QMap<int, QVariant> v;
        stream >> r >> c >> v;
        rows.append(r);
        columns.append(c);
        data.append(v);
        top = qMin(r, top);
        left = qMin(c, left);
        bottom = qMax(r, bottom);
        right = qMax(c, right);
    }

    // insert the dragged items into the table, use a bit array to avoid overwriting items,
    // since items from different tables can have the same row and column
    int dragRowCount = 0;
    int dragColumnCount = right - left + 1;

    // Compute the number of continuous rows upon insertion and modify the rows to match
    QVector<int> rowsToInsert(bottom + 1);
    for (int i = 0; i < rows.count(); ++i)
        rowsToInsert[rows.at(i)] = 1;
    for (int i = 0; i < rowsToInsert.count(); ++i) {
        if (rowsToInsert[i] == 1){
            rowsToInsert[i] = dragRowCount;
            ++dragRowCount;
        }
    }
    for (int i = 0; i < rows.count(); ++i)
        rows[i] = top + rowsToInsert[rows[i]];

    QBitArray isWrittenTo(dragRowCount * dragColumnCount);

    // make space in the table for the dropped data
    int colCount = columnCount(parent);
    if (colCount == 0) {
        insertColumns(colCount, dragColumnCount - colCount, parent);
        colCount = columnCount(parent);
    }
    insertRows(row, dragRowCount, parent);

    row = qMax(0, row);
    column = qMax(0, column);

    QVector<QPersistentModelIndex> newIndexes(data.size());
    // set the data in the table
    for (int j = 0; j < data.size(); ++j) {
        int relativeRow = rows.at(j) - top;
        int relativeColumn = columns.at(j) - left;
        int destinationRow = relativeRow + row;
        int destinationColumn = relativeColumn + column;
        int flat = (relativeRow * dragColumnCount) + relativeColumn;
        // if the item was already written to, or we just can't fit it in the table, create a new row
        if (destinationColumn >= colCount || isWrittenTo.testBit(flat)) {
            destinationColumn = qBound(column, destinationColumn, colCount - 1);
            destinationRow = row + dragRowCount;
            insertRows(row + dragRowCount, 1, parent);
            flat = (dragRowCount * dragColumnCount) + relativeColumn;
            isWrittenTo.resize(++dragRowCount * dragColumnCount);
        }
        if (!isWrittenTo.testBit(flat)) {
            newIndexes[j] = index(destinationRow, destinationColumn, parent);
            isWrittenTo.setBit(flat);
        }
    }

    for(int k = 0; k < newIndexes.size(); k++) {
        if (newIndexes.at(k).isValid())
            setItemData(newIndexes.at(k), data.at(k));
    }

    return true;
}

/*!
    Begins a row insertion operation.

    When reimplementing insertRows() in a subclass, you must call this function
    \e before inserting data into the model's underlying data store.

    The \a parent index corresponds to the parent into which the new rows are
    inserted; \a first and \a last are the row numbers that the new rows will
    have after they have been inserted.

    \table 80%
    \row
        \o  \inlineimage modelview-begin-insert-rows.png Inserting rows
        \o  Specify the first and last row numbers for the span of rows you
            want to insert into an item in a model.

            For example, as shown in the diagram, we insert three rows before
            row 2, so \a first is 2 and \a last is 4:

            \snippet doc/src/snippets/code/src_corelib_kernel_qabstractitemmodel.cpp 0

            This inserts the three new rows as rows 2, 3, and 4.
    \row
        \o  \inlineimage modelview-begin-append-rows.png Appending rows
        \o  To append rows, insert them after the last row.

            For example, as shown in the diagram, we append two rows to a
            collection of 4 existing rows (ending in row 3), so \a first is 4
            and \a last is 5:

            \snippet doc/src/snippets/code/src_corelib_kernel_qabstractitemmodel.cpp 1

            This appends the two new rows as rows 4 and 5.
    \endtable

    \note This function emits the rowsAboutToBeInserted() signal which
    connected views (or proxies) must handle before the data is inserted.
    Otherwise, the views may end up in an invalid state.
    \sa endInsertRows()
*/
void QAbstractItemModel::beginInsertRows(const QModelIndex &parent, int first, int last)
{
    Q_ASSERT(first >= 0);
    Q_ASSERT(last >= first);
    Q_D(QAbstractItemModel);
    d->changes.push(QAbstractItemModelPrivate::Change(parent, first, last));
    emit rowsAboutToBeInserted(parent, first, last);
    d->rowsAboutToBeInserted(parent, first, last);
}

/*!
    Ends a row insertion operation.

    When reimplementing insertRows() in a subclass, you must call this function
    \e after inserting data into the model's underlying data store.

    \sa beginInsertRows()
*/
void QAbstractItemModel::endInsertRows()
{
    Q_D(QAbstractItemModel);
    QAbstractItemModelPrivate::Change change = d->changes.pop();
    d->rowsInserted(change.parent, change.first, change.last);
    emit rowsInserted(change.parent, change.first, change.last);
}

/*!
    Begins a row removal operation.

    When reimplementing removeRows() in a subclass, you must call this
    function \e before removing data from the model's underlying data store.

    The \a parent index corresponds to the parent from which the new rows are
    removed; \a first and \a last are the row numbers of the rows to be
    removed.

    \table 80%
    \row
        \o  \inlineimage modelview-begin-remove-rows.png Removing rows
        \o  Specify the first and last row numbers for the span of rows you
            want to remove from an item in a model.

            For example, as shown in the diagram, we remove the two rows from
            row 2 to row 3, so \a first is 2 and \a last is 3:

            \snippet doc/src/snippets/code/src_corelib_kernel_qabstractitemmodel.cpp 2
    \endtable

    \note This function emits the rowsAboutToBeRemoved() signal which connected
    views (or proxies) must handle before the data is removed. Otherwise, the
    views may end up in an invalid state.

    \sa endRemoveRows()
*/
void QAbstractItemModel::beginRemoveRows(const QModelIndex &parent, int first, int last)
{
    Q_ASSERT(first >= 0);
    Q_ASSERT(last >= first);
    Q_D(QAbstractItemModel);
    d->changes.push(QAbstractItemModelPrivate::Change(parent, first, last));
    emit rowsAboutToBeRemoved(parent, first, last);
    d->rowsAboutToBeRemoved(parent, first, last);
}

/*!
    Ends a row removal operation.

    When reimplementing removeRows() in a subclass, you must call this function
    \e after removing data from the model's underlying data store.

    \sa beginRemoveRows()
*/
void QAbstractItemModel::endRemoveRows()
{
    Q_D(QAbstractItemModel);
    QAbstractItemModelPrivate::Change change = d->changes.pop();
    d->rowsRemoved(change.parent, change.first, change.last);
    emit rowsRemoved(change.parent, change.first, change.last);
}

/*!
    Returns whether a move operation is valid.

    A move operation is not allowed if it moves a continuous range of rows to a destination within
    itself, or if it attempts to move a row to one of its own descendants.

    \internal
*/
bool QAbstractItemModelPrivate::allowMove(const QModelIndex &srcParent, int start, int end, const QModelIndex &destinationParent, int destinationStart, Qt::Orientation orientation)
{
    // Don't move the range within itself.
    if (destinationParent == srcParent)
        return !(destinationStart >= start && destinationStart <= end + 1);

    QModelIndex destinationAncestor = destinationParent;
    int pos = (Qt::Vertical == orientation) ? destinationAncestor.row() : destinationAncestor.column();
    forever {
        if (destinationAncestor == srcParent) {
            if (pos >= start && pos <= end)
                return false;
            break;
        }

        if (!destinationAncestor.isValid())
          break;

        pos = (Qt::Vertical == orientation) ? destinationAncestor.row() : destinationAncestor.column();
        destinationAncestor = destinationAncestor.parent();
    }

    return true;
}

/*!
    Begins a row move operation.

    When reimplementing a subclass, this method simplifies moving
    entities in your model. This method is responsible for moving
    persistent indexes in the model, which you would otherwise be
    required to do yourself.

    Using beginMoveRows and endMoveRows is an alternative to emitting
    layoutAboutToBeChanged and layoutChanged directly along with
    changePersistentIndexes.  layoutAboutToBeChanged is emitted by
    this method for compatibility reasons.

    The \a sourceParent index corresponds to the parent from which the
    rows are moved; \a sourceFirst and \a sourceLast are the row
    numbers of the rows to be moved. The \a destinationParent index
    corresponds to the parent into which the rows are moved. The \a
    destinationChild is the row to which the rows will be moved.  That
    is, the index at row \a sourceFirst in \a sourceParent will become
    row \a destinationChild in \a destinationParent. Its siblings will
    be moved correspondingly.

    Note that \a sourceParent and \a destinationParent may be the
    same, in which case you must ensure that the \a destinationChild is
    not within the range of \a sourceFirst and \a sourceLast.  You
    must also ensure that you do not attempt to move a row to one of
    its own chilren or ancestors.  This method returns false if either
    condition is true, in which case you should abort your move
    operation.

    \sa endMoveRows()

    \since 4.6
*/
bool QAbstractItemModel::beginMoveRows(const QModelIndex &sourceParent, int sourceFirst, int sourceLast, const QModelIndex &destinationParent, int destinationChild)
{
    Q_ASSERT(sourceFirst >= 0);
    Q_ASSERT(sourceLast >= sourceFirst);
    Q_ASSERT(destinationChild >= 0);
    Q_D(QAbstractItemModel);

    if (!d->allowMove(sourceParent, sourceFirst, sourceLast, destinationParent, destinationChild, Qt::Vertical)) {
        return false;
    }

    d->changes.push(QAbstractItemModelPrivate::Change(sourceParent, sourceFirst, sourceLast));
    int destinationLast = destinationChild + (sourceLast - sourceFirst);
    d->changes.push(QAbstractItemModelPrivate::Change(destinationParent, destinationChild, destinationLast));

    emit rowsAboutToBeMoved(sourceParent, sourceFirst, sourceLast, destinationParent, destinationChild);
    emit layoutAboutToBeChanged();
    d->itemsAboutToBeMoved(sourceParent, sourceFirst, sourceLast, destinationParent, destinationChild, Qt::Vertical);
    return true;
}

/*!
    Ends a row move operation.

    When implementing a subclass, you must call this
    function \e after moving data within the model's underlying data
    store.

    layoutChanged is emitted by this method for compatibility reasons.

    \sa beginMoveRows()

    \since 4.6
*/
void QAbstractItemModel::endMoveRows()
{
    Q_D(QAbstractItemModel);

    QAbstractItemModelPrivate::Change insertChange = d->changes.pop();
    QAbstractItemModelPrivate::Change removeChange = d->changes.pop();

    d->itemsMoved(removeChange.parent, removeChange.first, removeChange.last, insertChange.parent, insertChange.first, Qt::Vertical);

    emit rowsMoved(removeChange.parent, removeChange.first, removeChange.last, insertChange.parent, insertChange.first);
    emit layoutChanged();
}

/*!
    Begins a column insertion operation.

    When reimplementing insertColumns() in a subclass, you must call this
    function \e before inserting data into the model's underlying data store.

    The \a parent index corresponds to the parent into which the new columns
    are inserted; \a first and \a last are the column numbers of the new
    columns will have after they have been inserted.

    \table 80%
    \row
        \o  \inlineimage modelview-begin-insert-columns.png Inserting columns
        \o  Specify the first and last column numbers for the span of columns
            you want to insert into an item in a model.

            For example, as shown in the diagram, we insert three columns
            before column 4, so \a first is 4 and \a last is 6:

            \snippet doc/src/snippets/code/src_corelib_kernel_qabstractitemmodel.cpp 3

            This inserts the three new columns as columns 4, 5, and 6.
    \row
        \o  \inlineimage modelview-begin-append-columns.png Appending columns
        \o  To append columns, insert them after the last column.

            For example, as shown in the diagram, we append three columns to a
            collection of six existing columns (ending in column 5), so
            \a first is 6 and \a last is 8:

            \snippet doc/src/snippets/code/src_corelib_kernel_qabstractitemmodel.cpp 4

            This appends the two new columns as columns 6, 7, and 8.
    \endtable

    \note This function emits the columnsAboutToBeInserted() signal which
    connected views (or proxies) must handle before the data is inserted.
    Otherwise, the views may end up in an invalid state.

    \sa endInsertColumns()
*/
void QAbstractItemModel::beginInsertColumns(const QModelIndex &parent, int first, int last)
{
    Q_ASSERT(first >= 0);
    Q_ASSERT(last >= first);
    Q_D(QAbstractItemModel);
    d->changes.push(QAbstractItemModelPrivate::Change(parent, first, last));
    emit columnsAboutToBeInserted(parent, first, last);
    d->columnsAboutToBeInserted(parent, first, last);
}

/*!
    Ends a column insertion operation.

    When reimplementing insertColumns() in a subclass, you must call this
    function \e after inserting data into the model's underlying data
    store.

    \sa beginInsertColumns()
*/
void QAbstractItemModel::endInsertColumns()
{
    Q_D(QAbstractItemModel);
    QAbstractItemModelPrivate::Change change = d->changes.pop();
    d->columnsInserted(change.parent, change.first, change.last);
    emit columnsInserted(change.parent, change.first, change.last);
}

/*!
    Begins a column removal operation.

    When reimplementing removeColumns() in a subclass, you must call this
    function \e before removing data from the model's underlying data store.

    The \a parent index corresponds to the parent from which the new columns
    are removed; \a first and \a last are the column numbers of the first and
    last columns to be removed.

    \table 80%
    \row
        \o  \inlineimage modelview-begin-remove-columns.png Removing columns
        \o  Specify the first and last column numbers for the span of columns
            you want to remove from an item in a model.

            For example, as shown in the diagram, we remove the three columns
            from column 4 to column 6, so \a first is 4 and \a last is 6:

            \snippet doc/src/snippets/code/src_corelib_kernel_qabstractitemmodel.cpp 5
    \endtable

    \note This function emits the columnsAboutToBeRemoved() signal which
    connected views (or proxies) must handle before the data is removed.
    Otherwise, the views may end up in an invalid state.

    \sa endRemoveColumns()
*/
void QAbstractItemModel::beginRemoveColumns(const QModelIndex &parent, int first, int last)
{
    Q_ASSERT(first >= 0);
    Q_ASSERT(last >= first);
    Q_D(QAbstractItemModel);
    d->changes.push(QAbstractItemModelPrivate::Change(parent, first, last));
    emit columnsAboutToBeRemoved(parent, first, last);
    d->columnsAboutToBeRemoved(parent, first, last);
}

/*!
    Ends a column removal operation.

    When reimplementing removeColumns() in a subclass, you must call this
    function \e after removing data from the model's underlying data store.

    \sa beginRemoveColumns()
*/
void QAbstractItemModel::endRemoveColumns()
{
    Q_D(QAbstractItemModel);
    QAbstractItemModelPrivate::Change change = d->changes.pop();
    d->columnsRemoved(change.parent, change.first, change.last);
    emit columnsRemoved(change.parent, change.first, change.last);
}

/*!
    Begins a column move operation.

    When reimplementing a subclass, this method simplifies moving
    entities in your model. This method is responsible for moving
    persistent indexes in the model, which you would otherwise be
    required to do yourself.

    Using beginMoveColumns and endMoveColumns is an alternative to
    emitting layoutAboutToBeChanged and layoutChanged directly along
    with changePersistentIndexes.  layoutAboutToBeChanged is emitted
    by this method for compatibility reasons.

    The \a sourceParent index corresponds to the parent from which the
    columns are moved; \a sourceFirst and \a sourceLast are the column
    numbers of the columns to be moved. The \a destinationParent index
    corresponds to the parent into which the columns are moved. The \a
    destinationChild is the column to which the columns will be
    moved.  That is, the index at column \a sourceFirst in \a
    sourceParent will become column \a destinationChild in \a
    destinationParent. Its siblings will be moved correspondingly.

    Note that \a sourceParent and \a destinationParent may be the
    same, in which case you must ensure that the \a destinationChild
    is not within the range of \a sourceFirst and \a sourceLast.  You
    must also ensure that you do not attempt to move a row to one of
    its own chilren or ancestors.  This method returns false if either
    condition is true, in which case you should abort your move
    operation.

    \sa endMoveColumns()

    \since 4.6
*/
bool QAbstractItemModel::beginMoveColumns(const QModelIndex &sourceParent, int sourceFirst, int sourceLast, const QModelIndex &destinationParent, int destinationChild)
{
    Q_ASSERT(sourceFirst >= 0);
    Q_ASSERT(sourceLast >= sourceFirst);
    Q_ASSERT(destinationChild >= 0);
    Q_D(QAbstractItemModel);

    if (!d->allowMove(sourceParent, sourceFirst, sourceLast, destinationParent, destinationChild, Qt::Horizontal)) {
        return false;
    }

    d->changes.push(QAbstractItemModelPrivate::Change(sourceParent, sourceFirst, sourceLast));
    int destinationLast = destinationChild + (sourceLast - sourceFirst);
    d->changes.push(QAbstractItemModelPrivate::Change(destinationParent, destinationChild, destinationLast));

    d->itemsAboutToBeMoved(sourceParent, sourceFirst, sourceLast, destinationParent, destinationChild, Qt::Horizontal);

    emit columnsAboutToBeMoved(sourceParent, sourceFirst, sourceLast, destinationParent, destinationChild);
    emit layoutAboutToBeChanged();
    return true;
}

/*!
    Ends a column move operation.

    When implementing a subclass, you must call this
    function \e after moving data within the model's underlying data
    store.

    layoutChanged is emitted by this method for compatibility reasons.

    \sa beginMoveColumns()

    \since 4.6
*/
void QAbstractItemModel::endMoveColumns()
{
    Q_D(QAbstractItemModel);

    QAbstractItemModelPrivate::Change insertChange = d->changes.pop();
    QAbstractItemModelPrivate::Change removeChange = d->changes.pop();

    d->itemsMoved(removeChange.parent, removeChange.first, removeChange.last, insertChange.parent, insertChange.first, Qt::Horizontal);

    emit columnsMoved(removeChange.parent, removeChange.first, removeChange.last, insertChange.parent, insertChange.first);
    emit layoutChanged();
}

/*!
    Resets the model to its original state in any attached views.

    \note Use beginResetModel() and endResetModel() instead whenever possible.
    Use this method only if there is no way to call beginResetModel() before invalidating the model.
    Otherwise it could lead to unexcpected behaviour, especially when used with proxy models.
*/
void QAbstractItemModel::reset()
{
    Q_D(QAbstractItemModel);
    emit modelAboutToBeReset();
    d->invalidatePersistentIndexes();
    emit modelReset();
}

/*!
    Begins a model reset operation.

    A reset operation resets the model to its current state in any attached views.

    \note Any views attached to this model will be reset as well.

    When a model is reset it means that any previous data reported from the
    model is now invalid and has to be queried for again. This also means that
    the current item and any selected items will become invalid.

    When a model radically changes its data it can sometimes be easier to just
    call this function rather than emit dataChanged() to inform other
    components when the underlying data source, or its structure, has changed.

    You must call this function before resetting any internal data structures in your model
    or proxy model.

    \sa modelAboutToBeReset(), modelReset(), endResetModel()
    \since 4.6
*/
void QAbstractItemModel::beginResetModel()
{
    emit modelAboutToBeReset();
}

/*!
    Completes a model reset operation.

    You must call this function after resetting any internal data structure in your model
    or proxy model.

    \sa beginResetModel()
    \since 4.6
*/
void QAbstractItemModel::endResetModel()
{
    Q_D(QAbstractItemModel);
    d->invalidatePersistentIndexes();
    emit modelReset();
}

/*!
    Changes the QPersistentModelIndex that is equal to the given \a from model
    index to the given \a to model index.

    If no persistent model index equal to the given \a from model index was
    found, nothing is changed.

    \sa persistentIndexList(), changePersistentIndexList()
*/
void QAbstractItemModel::changePersistentIndex(const QModelIndex &from, const QModelIndex &to)
{
    Q_D(QAbstractItemModel);
    if (d->persistent.indexes.isEmpty())
        return;
    // find the data and reinsert it sorted
    const QHash<QModelIndex, QPersistentModelIndexData *>::iterator it = d->persistent.indexes.find(from);
    if (it != d->persistent.indexes.end()) {
        QPersistentModelIndexData *data = *it;
        d->persistent.indexes.erase(it);
        data->index = to;
        if (to.isValid())
            d->persistent.insertMultiAtEnd(to, data);
        else
            data->model = 0;
    }
}

/*!
    \since 4.1

    Changes the QPersistentModelIndexes that is equal to the indexes in the
    given \a from model index list to the given \a to model index list.

    If no persistent model indexes equal to the indexes in the given \a from
    model index list was found, nothing is changed.

    \sa persistentIndexList(), changePersistentIndex()
*/
void QAbstractItemModel::changePersistentIndexList(const QModelIndexList &from,
                                                   const QModelIndexList &to)
{
    Q_D(QAbstractItemModel);
    if (d->persistent.indexes.isEmpty())
        return;
    QVector<QPersistentModelIndexData *> toBeReinserted;
    toBeReinserted.reserve(to.count());
    for (int i = 0; i < from.count(); ++i) {
        if (from.at(i) == to.at(i))
            continue;
        const QHash<QModelIndex, QPersistentModelIndexData *>::iterator it = d->persistent.indexes.find(from.at(i));
        if (it != d->persistent.indexes.end()) {
            QPersistentModelIndexData *data = *it;
            d->persistent.indexes.erase(it);
            data->index = to.at(i);
            if (data->index.isValid())
                toBeReinserted << data;
            else
                data->model = 0;
        }
    }

    for (QVector<QPersistentModelIndexData *>::const_iterator it = toBeReinserted.constBegin();
         it != toBeReinserted.constEnd() ; ++it) {
        QPersistentModelIndexData *data = *it;
        d->persistent.insertMultiAtEnd(data->index, data);
    }
}

/*!
    \since 4.2

    Returns the list of indexes stored as persistent indexes in the model.
*/
QModelIndexList QAbstractItemModel::persistentIndexList() const
{
    Q_D(const QAbstractItemModel);
    QModelIndexList result;
    for (QHash<QModelIndex, QPersistentModelIndexData *>::const_iterator it = d->persistent.indexes.constBegin();
         it != d->persistent.indexes.constEnd(); ++it) {
        QPersistentModelIndexData *data = *it;
        result.append(data->index);
    }
    return result;
}


/*!
    \class QAbstractTableModel
    \brief The QAbstractTableModel class provides an abstract model that can be
    subclassed to create table models.

    \ingroup model-view

    QAbstractTableModel provides a standard interface for models that represent
    their data as a two-dimensional array of items. It is not used directly,
    but must be subclassed.

    Since the model provides a more specialized interface than
    QAbstractItemModel, it is not suitable for use with tree views, although it
    can be used to provide data to a QListView. If you need to represent a
    simple list of items, and only need a model to contain a single column of
    data, subclassing the QAbstractListModel may be more appropriate.

    The rowCount() and columnCount() functions return the dimensions of the
    table. To retrieve a model index corresponding to an item in the model, use
    index() and provide only the row and column numbers.

    \section1 Subclassing

    When subclassing QAbstractTableModel, you must implement rowCount(),
    columnCount(), and data(). Default implementations of the index() and
    parent() functions are provided by QAbstractTableModel.
    Well behaved models will also implement headerData().

    Editable models need to implement setData(), and implement flags() to
    return a value containing
    \l{Qt::ItemFlags}{Qt::ItemIsEditable}.

    Models that provide interfaces to resizable data structures can
    provide implementations of insertRows(), removeRows(), insertColumns(),
    and removeColumns(). When implementing these functions, it is
    important to call the appropriate functions so that all connected views
    are aware of any changes:

    \list
    \o An insertRows() implementation must call beginInsertRows()
       \e before inserting new rows into the data structure, and it must
       call endInsertRows() \e{immediately afterwards}.
    \o An insertColumns() implementation must call beginInsertColumns()
       \e before inserting new columns into the data structure, and it must
       call endInsertColumns() \e{immediately afterwards}.
    \o A removeRows() implementation must call beginRemoveRows()
       \e before the rows are removed from the data structure, and it must
       call endRemoveRows() \e{immediately afterwards}.
    \o A removeColumns() implementation must call beginRemoveColumns()
       \e before the columns are removed from the data structure, and it must
       call endRemoveColumns() \e{immediately afterwards}.
    \endlist

    \note Some general guidelines for subclassing models are available in the
    \l{Model Subclassing Reference}.

    \note

    \sa {Model Classes}, QAbstractItemModel, QAbstractListModel,
    {Pixelator Example}
*/

/*!
    Constructs an abstract table model for the given \a parent.
*/

QAbstractTableModel::QAbstractTableModel(QObject *parent)
    : QAbstractItemModel(parent)
{

}

/*!
    \internal

    Constructs an abstract table model with \a dd and the given \a parent.
*/

QAbstractTableModel::QAbstractTableModel(QAbstractItemModelPrivate &dd, QObject *parent)
    : QAbstractItemModel(dd, parent)
{

}

/*!
    Destroys the abstract table model.
*/

QAbstractTableModel::~QAbstractTableModel()
{

}

/*!
    \fn QModelIndex QAbstractTableModel::index(int row, int column, const QModelIndex &parent = QModelIndex()) const

    Returns the index of the data in \a row and \a column with \a parent.

    \sa parent()
*/

QModelIndex QAbstractTableModel::index(int row, int column, const QModelIndex &parent) const
{
    return hasIndex(row, column, parent) ? createIndex(row, column, 0) : QModelIndex();
}

/*!
    \fn QModelIndex QAbstractTableModel::parent(const QModelIndex &index) const

    Returns the parent of the model item with the given \a index.

    \sa index() hasChildren()
*/

QModelIndex QAbstractTableModel::parent(const QModelIndex &) const
{
    return QModelIndex();
}

bool QAbstractTableModel::hasChildren(const QModelIndex &parent) const
{
    if (parent.model() == this || !parent.isValid())
        return rowCount(parent) > 0 && columnCount(parent) > 0;
    return false;
}

/*!
    \class QAbstractListModel
    \brief The QAbstractListModel class provides an abstract model that can be
    subclassed to create one-dimensional list models.

    \ingroup model-view

    QAbstractListModel provides a standard interface for models that represent
    their data as a simple non-hierarchical sequence of items. It is not used
    directly, but must be subclassed.

    Since the model provides a more specialized interface than
    QAbstractItemModel, it is not suitable for use with tree views; you will
    need to subclass QAbstractItemModel if you want to provide a model for
    that purpose. If you need to use a number of list models to manage data,
    it may be more appropriate to subclass QAbstractTableModel class instead.

    Simple models can be created by subclassing this class and implementing
    the minimum number of required functions. For example, we could implement
    a simple read-only QStringList-based model that provides a list of strings
    to a QListView widget. In such a case, we only need to implement the
    rowCount() function to return the number of items in the list, and the
    data() function to retrieve items from the list.

    Since the model represents a one-dimensional structure, the rowCount()
    function returns the total number of items in the model. The columnCount()
    function is implemented for interoperability with all kinds of views, but
    by default informs views that the model contains only one column.

    \section1 Subclassing

    When subclassing QAbstractListModel, you must provide implementations
    of the rowCount() and data() functions. Well behaved models also provide
    a headerData() implementation.

    For editable list models, you must also provide an implementation of
    setData(), implement the flags() function so that it returns a value
    containing \l{Qt::ItemFlags}{Qt::ItemIsEditable}.

    Note that QAbstractListModel provides a default implementation of
    columnCount() that informs views that there is only a single column
    of items in this model.

    Models that provide interfaces to resizable list-like data structures
    can provide implementations of insertRows() and removeRows(). When
    implementing these functions, it is important to call the appropriate
    functions so that all connected views are aware of any changes:

    \list
    \o An insertRows() implementation must call beginInsertRows()
       \e before inserting new rows into the data structure, and it must
       call endInsertRows() \e{immediately afterwards}.
    \o A removeRows() implementation must call beginRemoveRows()
       \e before the rows are removed from the data structure, and it must
       call endRemoveRows() \e{immediately afterwards}.
    \endlist

    \note Some general guidelines for subclassing models are available in the
    \l{Model Subclassing Reference}.

    \sa {Model Classes}, {Model Subclassing Reference}, QAbstractItemView,
        QAbstractTableModel, {Item Views Puzzle Example}
*/

/*!
    Constructs an abstract list model with the given \a parent.
*/

QAbstractListModel::QAbstractListModel(QObject *parent)
    : QAbstractItemModel(parent)
{

}

/*!
    \internal

    Constructs an abstract list model with \a dd and the given \a parent.
*/

QAbstractListModel::QAbstractListModel(QAbstractItemModelPrivate &dd, QObject *parent)
    : QAbstractItemModel(dd, parent)
{

}

/*!
    Destroys the abstract list model.
*/

QAbstractListModel::~QAbstractListModel()
{

}

/*!
    \fn QModelIndex QAbstractListModel::index(int row, int column, const QModelIndex &parent = QModelIndex()) const

    Returns the index of the data in \a row and \a column with \a parent.

    \sa parent()
*/

QModelIndex QAbstractListModel::index(int row, int column, const QModelIndex &parent) const
{
    return hasIndex(row, column, parent) ? createIndex(row, column, 0) : QModelIndex();
}

/*!
    Returns the parent of the model item with the given \a index.

    \sa index() hasChildren()
*/

QModelIndex QAbstractListModel::parent(const QModelIndex & /* index */) const
{
    return QModelIndex();
}

/*!
    \internal

    Returns the number of columns in the list with the given \a parent.

    \sa rowCount()
*/

int QAbstractListModel::columnCount(const QModelIndex &parent) const
{
    return parent.isValid() ? 0 : 1;
}

bool QAbstractListModel::hasChildren(const QModelIndex &parent) const
{
    return parent.isValid() ? false : (rowCount() > 0);
}

/*!
    \typedef QModelIndexList
    \relates QModelIndex

    Synonym for QList<QModelIndex>.
*/

/*!
  \reimp
*/
bool QAbstractTableModel::dropMimeData(const QMimeData *data, Qt::DropAction action,
                                       int row, int column, const QModelIndex &parent)
{
    if (!data || !(action == Qt::CopyAction || action == Qt::MoveAction))
        return false;

    QStringList types = mimeTypes();
    if (types.isEmpty())
        return false;
    QString format = types.at(0);
    if (!data->hasFormat(format))
        return false;

    QByteArray encoded = data->data(format);
    QDataStream stream(&encoded, QIODevice::ReadOnly);

    // if the drop is on an item, replace the data in the items
    if (parent.isValid() && row == -1 && column == -1) {
        int top = INT_MAX;
        int left = INT_MAX;
        QVector<int> rows, columns;
        QVector<QMap<int, QVariant> > data;

        while (!stream.atEnd()) {
            int r, c;
            QMap<int, QVariant> v;
            stream >> r >> c >> v;
            rows.append(r);
            columns.append(c);
            data.append(v);
            top = qMin(r, top);
            left = qMin(c, left);
        }

        for (int i = 0; i < data.size(); ++i) {
            int r = (rows.at(i) - top) + parent.row();
            int c = (columns.at(i) - left) + parent.column();
            if (hasIndex(r, c))
                setItemData(index(r, c), data.at(i));
        }

        return true;
    }

    // otherwise insert new rows for the data
    return decodeData(row, column, parent, stream);
}

/*!
  \reimp
*/
bool QAbstractListModel::dropMimeData(const QMimeData *data, Qt::DropAction action,
                                      int row, int column, const QModelIndex &parent)
{
    if (!data || !(action == Qt::CopyAction || action == Qt::MoveAction))
        return false;

    QStringList types = mimeTypes();
    if (types.isEmpty())
        return false;
    QString format = types.at(0);
    if (!data->hasFormat(format))
        return false;

    QByteArray encoded = data->data(format);
    QDataStream stream(&encoded, QIODevice::ReadOnly);

    // if the drop is on an item, replace the data in the items
    if (parent.isValid() && row == -1 && column == -1) {
        int top = INT_MAX;
        int left = INT_MAX;
        QVector<int> rows, columns;
        QVector<QMap<int, QVariant> > data;

        while (!stream.atEnd()) {
            int r, c;
            QMap<int, QVariant> v;
            stream >> r >> c >> v;
            rows.append(r);
            columns.append(c);
            data.append(v);
            top = qMin(r, top);
            left = qMin(c, left);
        }

        for (int i = 0; i < data.size(); ++i) {
            int r = (rows.at(i) - top) + parent.row();
            if (columns.at(i) == left && hasIndex(r, 0))
                setItemData(index(r), data.at(i));
        }

        return true;
    }

    if (row == -1)
        row = rowCount(parent);

    // otherwise insert new rows for the data
    return decodeData(row, column, parent, stream);
}

/*!
    \fn QAbstractItemModel::modelAboutToBeReset()
    \since 4.2

    This signal is emitted when reset() is called, before the model's internal
    state (e.g. persistent model indexes) has been invalidated.

    \sa beginResetModel(), modelReset()
*/

/*!
    \fn QAbstractItemModel::modelReset()
    \since 4.1

    This signal is emitted when reset() is called, after the model's internal
    state (e.g. persistent model indexes) has been invalidated.

    \sa endResetModel(), modelAboutToBeReset()
*/

/*!
    \fn bool QModelIndex::operator<(const QModelIndex &other) const
    \since 4.1

    Returns true if this model index is smaller than the \a other
    model index; otherwise returns false.
*/

/*!
    \fn uint qHash(const QPersistentModelIndex &index)
    \since 4.5

    Returns a hash of the QPersistentModelIndex
 */


/*!
    \internal
    QHash::insertMulti insert the value before the old value. and find() return the new value.
    We need insertMultiAtEnd because we don't want to overwrite the old one, which should be removed later

    There should be only one instance QPersistentModelIndexData per index, but in some intermediate state there may be
    severals of PersistantModelIndex pointing to the same index, but one is already updated, and the other one is not.
    This make sure than when updating the first one we don't overwrite the second one in the hash, and the second one
    will be updated right later.
 */
void QAbstractItemModelPrivate::Persistent::insertMultiAtEnd(const QModelIndex& key, QPersistentModelIndexData *data)
{
    QHash<QModelIndex,QPersistentModelIndexData *>::iterator newIt =
            indexes.insertMulti(key, data);
    QHash<QModelIndex,QPersistentModelIndexData *>::iterator it = newIt + 1;
    while (it != indexes.end() && it.key() == key) {
        qSwap(*newIt,*it);
        newIt = it;
        ++it;
    }
}

QT_END_NAMESPACE