summaryrefslogtreecommitdiff
path: root/src/lib/eina/eina_promise.h
blob: cad96b4049a14212526834a02c7c43e4455f16c8 (plain) (blame)
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
#ifndef _EINA_PROMISE_H_
#define _EINA_PROMISE_H_

#ifdef __cplusplus
extern "C" {
#endif

#include "eina_safety_checks.h"
#include "eina_types.h"
#include "eina_value.h"

/** @file */

/** @struct Eina_Promise
 * @ingroup Eina_Promise
 * An opaque structure representing a piece of data that will be available at a later point.
 * @typedef struct _Eina_Promise Eina_Promise
 * Convenience wrapper.
 */
typedef struct _Eina_Promise Eina_Promise;

/** @struct Eina_Future
 * @ingroup Eina_Future
 * An opaque structure representing a callback to be called when a promise is fulfilled.
 * @typedef struct _Eina_Future Eina_Future
 * Convenience wrapper.
 */
typedef struct _Eina_Future Eina_Future;

/** @typedef struct _Eina_Future_Desc Eina_Future_Desc
 * @ingroup Eina_Future
 * Convenience wrapper over #_Eina_Future_Desc. */
typedef struct _Eina_Future_Desc Eina_Future_Desc;

/** @typedef struct _Eina_Future_Race_Result Eina_Future_Race_Result
 * @ingroup Eina_Future
 * Convenience wrapper over #_Eina_Future_Race_Result. */
typedef struct _Eina_Future_Race_Result Eina_Future_Race_Result;

/**
 * @defgroup Eina_Future_Callbacks Eina Future Callbacks
 * @ingroup Eina_Future
 * @brief Methods and structures dealing with #Eina_Future callbacks
 * @{
 */

/** @typedef struct _Eina_Future_Cb_Easy_Desc Eina_Future_Cb_Easy_Desc
 * Convenience wrapper over #_Eina_Future_Cb_Easy_Desc. */
typedef struct _Eina_Future_Cb_Easy_Desc Eina_Future_Cb_Easy_Desc;

/** @typedef struct _Eina_Future_Cb_Console_Desc Eina_Future_Cb_Console_Desc
 * Convenience wrapper over _Eina_Future_Cb_Console_Desc. */
typedef struct _Eina_Future_Cb_Console_Desc Eina_Future_Cb_Console_Desc;

/** @typedef struct _Eina_Future_Scheduler Eina_Future_Scheduler
 * Convenience wrapper over _Eina_Future_Scheduler. */
typedef struct _Eina_Future_Scheduler Eina_Future_Scheduler;

/** @typedef struct _Eina_Future_Schedule_Entry Eina_Future_Schedule_Entry
 * Convenience wrapper over _Eina_Future_Schedule_Entry. */
typedef struct _Eina_Future_Schedule_Entry Eina_Future_Schedule_Entry;

/** @typedef struct _Eina_Future_Cb_Log_Desc Eina_Future_Cb_Log_Desc
 * Convenience wrapper over _Eina_Future_Cb_Log_Desc. */
typedef struct _Eina_Future_Cb_Log_Desc Eina_Future_Cb_Log_Desc;

/**
 * @typedef Eina_Future_Cb
 
 * A callback used to inform that a future was resolved.
 * Usually this callback is called from a clean context, that is, from the
 * main loop or some platform defined safe context. However there are
 * 2 exceptions:
 *
 * @li eina_future_cancel() was used, it's called immediately in the
 * context that called cancel using `ECANCELED` as error.
 *
 * @li eina_future_then(), eina_future_then_from_desc(), eina_future_chain(), eina_future_chain_array()
 * or similar failed due to invalid pointer or memory allocation. Then the callback is called from the
 * failed context using `EINVAL` or `ENOMEM` as errors and @p dead_future will be @c NULL.
 *
 * @param[in] data The data provided by the user
 *
 * @param[in] value An #Eina_Value which contains the operation result. Before using
 * the @p value, its type must be checked in order to avoid errors. This is needed because
 * if an operation fails the #Eina_Value type will be #EINA_VALUE_TYPE_ERROR
 * which is a different type than the expected operation result.
 *
 * @param[in] dead_future A pointer to the future that was completed.
 *
 * @return An #Eina_Value to pass to the next #Eina_Future in the chain (if any).
 * If there is no need to convert the received value, it's @b recommended
 * to passthrough the @p value argument. If you need to convert to a different type
 * or generate a new value, use @c eina_value_setup() on @b another #Eina_Value
 * and return it. By returning a promise #Eina_Value (eina_promise_as_value()) the
 * whole chain will wait until the promise is resolved in
 * order to continue its execution.
 * Note that the value contents must survive this function scope,
 * that is, do @b not use stack allocated blobs, arrays, structures or types that
 * keep references to memory you give. Values will be automatically cleaned up
 * using @c eina_value_flush() once they are unused (no more future or futures
 * returned a new value).
 *
 * @note The returned value @b can be an #EINA_VALUE_TYPE_PROMISE! (see eina_promise_as_value() and
 * eina_future_as_value()) In this case the future chain will wait until the promise is resolved.
 *
 * @see eina_future_cancel()
 * @see eina_future_then()
 * @see eina_future_then_from_desc()
 * @see eina_future_then_easy()
 * @see eina_future_chain()
 * @see eina_future_chain_array()
 * @see eina_future_as_value()
 * @see eina_promise_as_value()
 */
typedef Eina_Value (*Eina_Future_Cb)(void *data, const Eina_Value value, const Eina_Future *dead_future);

/**
 * @struct _Eina_Future_Schedule_Entry
 *
 * A struct that represents an scheduled event.
 * This struct may be used by Eina to cancel
 * a scheduled future.
 *
 * @see eina_promise_new()
 *
 * @see Eina_Future_Scheduler
 * @see Eina_Future_Scheduler_Cb
 */
struct _Eina_Future_Schedule_Entry {
   /**
    * The scheduler used to create the entry.
    * @note This must not be @c NULL.
    */
   Eina_Future_Scheduler *scheduler;
};


/**
 * @typedef Eina_Future_Scheduler_Cb
 * A callback used by the #Eina_Future_Scheduler to deliver
 * the future operation result.
 *
 * @param[out] f The delivered future.
 * @param[in] value The future result
 *
 *
 * @see eina_promise_new()
 *
 * @see Eina_Future_Schedule_Entry
 * @see Eina_Future_Scheduler
 */
typedef void (*Eina_Future_Scheduler_Cb)(Eina_Future *f, Eina_Value value);

/**
 * @struct _Eina_Future_Scheduler
 * This struct is used as a bridge between Eina and the future scheduler.
 * By using the functions provided by _Eina_Future_Scheduler Eina can
 * schedule futures resolutions, rejections and cancellations to a safe context.
 *
 * @see eina_promise_new()
 * @see Eina_Future_Schedule_Entry
 * @see Eina_Future_Scheduler_Cb
 */
struct _Eina_Future_Scheduler {
   /**
    * Called by @p Eina_Future when a delivery must be scheduled to a safe context.
    * i.e.: after @p eina_promise_resolve()
    *
    * @note Must not be @c NULL
    *
    * Must call back from a safe context using @p cb(f,value)
    * @param[in,out] scheduler The scheduler to use.
    * @param[in] cb The Eina_Future_Scheduler_Cb to be called and deliver the @p f and @p value.
    * @param[in] f The future to be delivered to @p cb
    * @param[in] value The value to be delivered to @p cb
    * @return A scheduled entry or @c NULL on error
    */
   Eina_Future_Schedule_Entry *(*schedule)(Eina_Future_Scheduler *scheduler, Eina_Future_Scheduler_Cb cb, Eina_Future *f, Eina_Value value);
   /**
    * Called by @p Eina_Future when a delivery must be canceled.
    * i.e.: after @p eina_future_cancel()
    *
    * @note Must not be @c NULL.
    *
    * @param[in,out] entry The scheduled event to cancel
    */
   void (*recall)(Eina_Future_Schedule_Entry *entry);
};

/**
 * @typedef void (*Eina_Promise_Cancel_Cb) (void *data, const Eina_Promise *dead_promise)
 *
 * A callback used to inform that a promise was canceled.
 *
 * A promise may be canceled by the user calling `eina_future_cancel()`
 * on any #Eina_Future that is part of the chain that uses an #Eina_Promise,
 * that will cancel the whole chain and then the promise.
 *
 * It should stop all asynchronous operations or at least mark them to be
 * discarded instead of resolved. Actually it can't be resolved once
 * canceled since the given pointer @c dead_promise is now invalid.
 *
 * @note @li This callback is @b mandatory for a reason, do not provide an empty
 *       callback as it'll likely result in memory corruption and invalid access.
 *       If impossible to cancel an asynchronous task, then create an
 *       intermediate memory to hold #Eina_Promise and make it @c NULL,
 *       in this callback. Then prior to resolution check if the pointer is set.
 *
 * @note @li This callback is @b not called if eina_promise_resolve() or
 *       eina_promise_reject() are used. If any cleanup is needed, then
 *       call yourself. It's only meant as cancellation, not a general
 *       "free callback".
 *
 * @param[in] data The data provided by the user.
 * @param[in] dead_promise The canceled promise.
 * @see eina_promise_reject()
 * @see eina_promise_resolve()
 * @see eina_future_cancel()
 */
typedef void (*Eina_Promise_Cancel_Cb) (void *data, const Eina_Promise *dead_promise);

/**
 * @typedef Eina_Future_Success_Cb
 *
 * A callback used to inform that the future completed with success.
 *
 * Unlike #Eina_Future_Cb this callback is only called if the future operation was successful, this is,
 * no errors occurred (@p value type differs from #EINA_VALUE_TYPE_ERROR)
 * and the @p value matches _Eina_Future_Cb_Easy_Desc::success_type (if given).
 * In case _Eina_Future_Cb_Easy_Desc::success_type was not supplied (it's @c NULL) the @p value type
 * must be checked before using it.
 *
 * @note This function is always called from a safe context (main loop or some platform defined safe context).
 *
 * @param[in] data The data provided by the user.
 * @param[in] value The operation result
 * @return An Eina_Value to pass to the next Eina_Future in the chain (if any).
 * If there is no need to convert the received value, it's @b recommended
 * to passthrough @p value argument. If you need to convert to a different type
 * or generate a new value, use @c eina_value_setup() on @b another Eina_Value
 * and return it. By returning a promise Eina_Value (eina_promise_as_value()) the
 * whole chain will wait until the promise is resolved in
 * order to continue its execution.
 * Note that the value contents must survive this function scope,
 * that is, do @b not use stack allocated blobs, arrays, structures or types that
 * keep references to memory you give. Values will be automatically cleaned up
 * using @c eina_value_flush() once they are unused (no more future or futures
 * returned a new value).
 * @see eina_future_cb_easy_from_desc()
 * @see eina_future_cb_easy()
 */
typedef Eina_Value (*Eina_Future_Success_Cb)(void *data, const Eina_Value value);

/**
 * @typedef Eina_Future_Error_Cb
 *
 * A callback used to inform that the future completed with failure.
 *
 * Unlike #Eina_Future_Success_Cb this function is only called when an error
 * occurs during the future process or when _Eina_Future_Cb_Easy_Desc::success_type
 * differs from the future result.
 * On future creation errors and future cancellation this function will be called
 * from the current context with the following errors: `EINVAL`, `ENOMEM` and  `ECANCELED`.
 * Otherwise this function is called from a safe context.
 *
 * If it was possible to recover from an error this function should return an empty value
 * #EINA_VALUE_EMPTY or any other #Eina_Value type that differs from #EINA_VALUE_TYPE_ERROR.
 * In this case the error will not be reported by the other futures in the chain (if any), otherwise
 * if an #Eina_Value type #EINA_VALUE_TYPE_ERROR is returned the error will continue to be reported
 * to the other futures in the chain.
 *
 * @param[in] data The data provided by the user.
 * @param[in] error The operation error
 * @return An #Eina_Value to pass to the next #Eina_Future in the chain (if any).
 * If you need to convert to a different type or generate a new value,
 * use eina_value_setup() on @b another Eina_Value
 * and return it. By returning a promise Eina_Value (eina_promise_as_value()) the
 * whole chain will wait until the promise is resolved in
 * order to continue its execution.
 * Note that the value contents must survive this function scope,
 * that is, do @b not use stack allocated blobs, arrays, structures or types that
 * keep references to memory you give. Values will be automatically cleaned up
 * using eina_value_flush() once they are unused (no more future or futures
 * returned a new value).
 * @see eina_future_cb_easy_from_desc()
 * @see eina_future_cb_easy()
 */
typedef Eina_Value (*Eina_Future_Error_Cb)(void *data, const Eina_Error error);

/**
 * @typedef Eina_Future_Free_Cb
 *
 * A callback used to inform that the future was freed and the user should also @c free the @p data.
 * This callback may be called from an unsafe context if the future was canceled or an error
 * occurred.
 *
 * @note This callback is always called, even if #Eina_Future_Error_Cb and/or #Eina_Future_Success_Cb
 * were not provided, which can also be used to monitor when a future ends.
 *
 * @param[in] data The data provided by the user.
 * @param[in] dead_future The future that was freed.
 *
 * @see eina_future_cb_easy_from_desc()
 * @see eina_future_cb_easy()
 */
typedef void (*Eina_Future_Free_Cb)(void *data, const Eina_Future *dead_future);

/**
 * @struct _Eina_Future_Cb_Easy_Desc
 *
 * A struct with callbacks to be used by eina_future_cb_easy_from_desc() and eina_future_cb_easy()
 *
 * @see eina_future_cb_easy_from_desc()
 * @see eina_future_cb_easy()
 */
struct _Eina_Future_Cb_Easy_Desc {
   /**
    * Called on success (value.type is not @c EINA_VALUE_TYPE_ERROR).
    *
    * if @c success_type is not NULL, then the value is guaranteed to be of that type,
    * if it's not, then it will trigger @c error with @c EINVAL.
    *
    * After this function returns, @c free callback is called if provided.
    */
   Eina_Future_Success_Cb success;
   /**
    * Called on error (value.type is @c EINA_VALUE_TYPE_ERROR).
    *
    * This function can return another error, propagating or converting it. However it
    * may also return a non-error, in this case the next future in chain will receive a regular
    * value, which may call its @c success.
    *
    * If this function is not provided, then it will passthrough the error to the next error handler.
    *
    * It may be called with @c EINVAL if @c success_type is provided and doesn't
    * match the received type.
    *
    * It may be called with @c ECANCELED if future was canceled.
    *
    * It may be called with @c ENOMEM if memory allocation failed during callback creation.
    *
    * After this function returns, @c free callback is called if provided.
    */
   Eina_Future_Error_Cb error;
   /**
    * Called on @b all situations to notify future destruction.
    *
    * This is called after @c success or @c error, as well as it's called if none of them are
    * provided. Thus can be used as a "weak ref" mechanism.
    */
   Eina_Future_Free_Cb free;
   /**
    * If provided, then @c success will only be called if the value type matches the given pointer.
    *
    * If provided and doesn't match, then @c error will be called with @c EINVAL. If no @c error,
    * then it will be propagated to the next future in the chain.
    */
   const Eina_Value_Type *success_type;
   /**
    * Context data given to every callback.
    *
    * This must be freed @b only by @c free callback as it's called from every case,
    * otherwise it may lead to memory leaks.
    */
   const void *data;
};

/**
 * @struct _Eina_Future_Cb_Console_Desc
 *
 * A struct used to define the prefix and suffix to be printed
 * along side the a future value. This struct is used by
 * eina_future_cb_console_from_desc()
 *
 * @see eina_future_cb_console_from_desc()
 */
struct _Eina_Future_Cb_Console_Desc {
   /**
    * The prefix to be printed. If @c NULL an empty string ("") is used.
    */
   const char *prefix;
   /**
    * The suffix the be printed. If @c NULL '\n' is used.
    */
   const char *suffix;
};

/**
 * @struct _Eina_Future_Cb_Log_Desc
 *
 * This struct is used by eina_future_cb_log_from_desc() and
 * its contents will be routed to eina_log_print() along side
 * the future value.
 *
 * @see eina_future_cb_log_from_desc()
 */
struct _Eina_Future_Cb_Log_Desc {
   /**
    * The prefix to be printed. If @c NULL an empty string ("") is used.
    */
   const char *prefix;
   /**
    * The suffix the be printed. If @c NULL '\n' is used.
    */
   const char *suffix;
   /**
    * The file name to be passed to eina_log_print(). if @c NULL "Unknown file" is used.
    */
   const char *file;
   /**
    * The file name to be passed to eina_log_print(). if @c NULL "Unknown function" is used.
    */
   const char *func;
   /**
    * The Eina_Log_Level to use.
    */
   Eina_Log_Level level;
   /**
    * The log domain to use.
    */
   int domain;
   /**
    * The line number to be passed to eina_log_print().
    */
   int line;
};

/**
 * @}
 */

/**
 * @struct _Eina_Future_Desc
 * @ingroup Eina_Future
 * A struct used to define a callback and data for a future.
 *
 * This struct contains a future completion callback and a data to the future
 * completion callback which is used by eina_future_then(), eina_future_chain()
 * and friends to inform the user about the future result. The _Eina_Future_Desc::data
 * variable should be freed when _Eina_Future_Desc::cb is called, otherwise it will leak.
 *
 * @note If eina_future_then(), eina_future_chain() and friends fails to return a valid future
 * (in other words: @c NULL is returned) the _Eina_Future_Desc::cb will be called
 * report an error like `EINVAL` or `ENOMEM` so _Eina_Future_Desc::data can be freed.
 *
 * @see eina_future_then()
 * @see eina_future_chain_array()
 * @see eina_future_cb_convert_to()
 * @see eina_future_cb_console_from_desc()
 * @see eina_future_cb_ignore_error()
 * @see eina_future_cb_easy_from_desc()
 * @see eina_future_cb_log_from_desc()
 */
struct _Eina_Future_Desc {
   /**
    * Called when the future is resolved or rejected.
    *
    * Once a future is resolved or rejected this function is called passing the future result
    * to inform the user that the future operation has ended. Normally this
    * function is called from a safe context (main loop or some platform defined safe context),
    * however in case of a future cancellation (eina_future_cancel()) or if eina_future_then(),
    * eina_future_chain() and friends fails to create a new future,
    * this function is called from the current context.
    *
    * Use this function to free @p data if necessary.
    * @see eina_future_chain()
    * @see eina_future_then()
    * @see eina_future_cancel()
    */
   Eina_Future_Cb cb;
   /**
    * Context data to @p cb. The @p data should be freed inside @p cb, otherwise
    * its memory will leak!
    */
   const void *data;

   /**
    * The storage will be used by Eina to store a pointer to the
    * created future. It can be @c NULL.
    */
   Eina_Future **storage;
};

/**
 * @defgroup Eina_Promise Eina Promises
 * @ingroup Eina
 *
 * @brief Promises are a programming paradigm that simplifies synchronization when concurrent execution is present.
 *
 * Since C does not natively support Promises the Eina library provides the Eina_Promise and Eina_Future objects.
 *
 * In procedural languages like C if you need a value which is not yet available, for instance because
 * it takes a long time to calculate or has to be fetched from a remote server, you typically have to wait.
 *
 * Other languages however can return a Promise and continue execution immediately. A promise acts as a placeholder
 * for the requested value: the value is not available yet but will be at some point in the future.
 *
 * With a promise in hand you can attach callbacks to be triggered when the value becomes available (i.e. when
 * the promise is fulfilled) and then continue your calculations. You can even pass the promise to other methods
 * which will then be executed as values become available, forming complex chains.
 *
 * An Eina_Promise can be considered as an object with the sole purpose of emitting the "Promise Resolved" event.
 * Eina_Future are callbacks attached to this object to be called when the event is emitted. The promised value is
 * passed to the callbacks whenever it's available.
 *
 * Here's a typical example:
 *
 * @code
 * #include <Ecore.h>
 *
 * static void
 * _promise_cancel(void *data, Eina_Promise *p EINA_UNUSED)
 * {
 *   Ctx *ctx = data;
 *   // In case the promise is canceled we must stop the timer!
 *   ecore_timer_del(ctx->timer);
 *   free(ctx);
 * }
 *
 * static Eina_Bool
 * _promise_resolve(void *data)
 * {
 *    Ctx *ctx = data;
 *    Eina_Value v;
 *    eina_value_setup(&v, EINA_VALUE_TYPE_STRING);
 *    eina_value_set(&v, "Promise resolved");
 *    eina_promise_resolve(ctx->p, v);
 *    free(ctx);
 *    return EINA_FALSE;
 * }
 *
 * Eina_Promise *
 * promise_create(Eina_Future_Scheduler *scheduler)
 * {
 *    Ctx *ctx = malloc(sizeof(Ctx));
 *    // A timer is scheduled in order to resolve the promise
 *    ctx->timer = ecore_timer_add(122, _promise_resolve, ctx);
 *    // The _promise_cancel() will be used to clean ctx if the promise is canceled.
 *    ctx->p = eina_promise_new(scheduler, _promise_cancel, ctx);
 *    return ctx->p;
 * }
 * @endcode
 *
 * @{
 */

/**
 * Value type for #Eina_Value's containing an #Eina_Promise
 */
EAPI extern const Eina_Value_Type EINA_VALUE_TYPE_PROMISE;

/**
 * Creates a new promise.
 *
 * This function creates a new promise which can be used to create a future
 * using eina_future_new(). Every time a promise is created an #Eina_Promise_Cancel_Cb
 * must be provided which is used to free resources that were created.
 *
 * A promise may be canceled directly by calling:
 * @code
 * eina_future_cancel(eina_future_new(eina_promise_new(...)))
 * @endcode
 * That is, canceling any future that is chained to receive the results.
 *
 * However promises can be canceled indirectly by other entities.
 * These other entities will call eina_future_cancel() themselves,
 * however you may not be aware of that. Some common sources
 * of indirect cancellations:
 *
 * @li A subsystem was shutdown, canceling all pending futures (i.e.: ecore_shutdown())
 *
 * @li An EO object was linked to the promise or future, then if the object dies (last reference
 * is gone), then the pending promises and futures will be canceled.
 *
 * @li Some other entity (library provider or library user) chained and canceled his future,
 * which will result in your future being canceled.
 *
 * Since a promise may be canceled indirectly (by code sections that goes beyond your scope)
 * you should always provide a cancel callback, even if you think you'll not need it.
 *
 * If you already have a value and want to create a future that will
 * resolve to it directly use the eina_future_resolved(), it has the
 * same effect as creating a promise and immediately resolving it.
 *
 * @param[in,out] scheduler The scheduler.
 * @param[in] cancel_cb A callback used to inform that the promise was canceled. Use
 * this callback to @c free @p data. @p cancel_cb must not be @c NULL !
 * @param[in] data Data to @p cancel_cb.
 * @return A promise or @c NULL on error.
 * @see eina_future_cancel()
 * @see eina_future_new()
 * @see eina_promise_continue_new()
 * @see eina_promise_resolve()
 * @see eina_promise_reject()
 * @see eina_promise_as_value()
 * @see Eina_Future_Scheduler
 * @see Eina_Future_Schedule_Entry
 * @see Eina_Future_Scheduler_Cb
 */
EAPI Eina_Promise *eina_promise_new(Eina_Future_Scheduler *scheduler, Eina_Promise_Cancel_Cb cancel_cb, const void *data) EINA_ARG_NONNULL(1, 2) EINA_WARN_UNUSED_RESULT;

/**
 * Creates a new promise from a dead_future.
 *
 * This function creates a new promise from a future currently being resolved which can be
 * used to create a #Eina_Value with eina_promise_as_value(). Every time a promise is
 * created an #Eina_Promise_Cancel_Cb must be provided which is used to free resources
 * that were created.
 *
 * A promise may be canceled directly by calling:
 * @code
 * eina_future_cancel(eina_future_new(eina_promise_new(...)))
 * @endcode
 * That is, canceling any future that is chained to receive the results.
 *
 * However promises can be canceled indirectly by other entities.
 * These other entities will call eina_future_cancel() themselves,
 * however you may not be aware of that. Some common sources
 * of indirect cancellations:
 *
 * @li A subsystem was shutdown, canceling all pending futures (i.e.: ecore_shutdown())
 *
 * @li An EO object was linked to the promise or future, then if the object dies (last reference
 * is gone), then the pending promises and futures will be canceled.
 *
 * @li Some other entity (library provider or library user) chained and canceled his future,
 * which will result in your future being canceled.
 *
 * Since a promise may be canceled indirectly (by code sections that goes beyond your scope)
 * you should always provide a cancel callback, even if you think you'll not need it.
 *
 * Here's a typical example:
 *
 * @code
 * Eina_Value
 * _future_resolve(void *data, const Eina_Value v, const Eina_Future *dead_future)
 * {
 *    Eina_Promise *p;
 *    p = eina_promise_continue_new(dead_future, _promise_cancel, NULL);
 *    return eina_promise_as_value(p);
 * }
 * @endcode
 *
 * If you already have a value and want to create a future that will
 * resolve to it directly use the eina_future_resolved(), it has the
 * same effect as creating a promise and immediately resolving it.
 *
 * @note This function is to be used solely inside of a future resolve callback with
 * the #Eina_Value being returned from it.
 *
 * @param[in] dead_future The future being resolved to get a scheduler from.
 * @param[in] cancel_cb A callback used to inform that the promise was canceled. Use
 * this callback to @c free @p data. @p cancel_cb must not be @c NULL.
 * @param[in] data Data to @p cancel_cb.
 * @return A promise or @c NULL on error.
 * @see eina_future_cancel()
 * @see eina_future_new()
 * @see eina_promise_new()
 * @see eina_promise_resolve()
 * @see eina_promise_reject()
 * @see eina_promise_as_value()
 * @see Eina_Future_Scheduler
 * @see Eina_Future_Schedule_Entry
 * @see Eina_Future_Scheduler_Cb
 */
EAPI Eina_Promise *eina_promise_continue_new(const Eina_Future *dead_future, Eina_Promise_Cancel_Cb cancel_cb, const void *data) EINA_ARG_NONNULL(1, 2) EINA_WARN_UNUSED_RESULT;

/**
 * Resolves a promise.
 *
 * This function schedules a resolve event in a
 * safe context (main loop or some platform defined safe context),
 * whenever possible the future callbacks will be dispatched.
 *
 * @param[in,out] p A promise to resolve.
 * @param[in] value The value to be delivered.
 *
 * Note that the @p value contents must survive this function scope,
 * that is, do @b not use stack allocated blobs, arrays, structures or types that
 * keep references to memory you give. Values will be automatically cleaned up
 * using @c eina_value_flush() once they are unused (no more future or futures
 * returned a new value).
 *
 * @see eina_promise_new()
 * @see eina_promise_reject()
 * @see eina_promise_as_value()
 */
EAPI void eina_promise_resolve(Eina_Promise *p, Eina_Value value) EINA_ARG_NONNULL(1);

/**
 * Rejects a promise.
 *
 * This function schedules a reject event in a
 * safe context (main loop or some platform defined safe context),
 * whenever possible the future callbacks will be dispatched.
 *
 * @param[in,out] p A promise to reject.
 * @param[in] err An Eina_Error value
 * @note Internally this function will create an #Eina_Value with type #EINA_VALUE_TYPE_ERROR.
 *
 * @see eina_promise_new()
 * @see eina_promise_resolve()
 * @see eina_promise_as_value()
 */
EAPI void eina_promise_reject(Eina_Promise *p, Eina_Error err) EINA_ARG_NONNULL(1);


/**
 * @}
 */

/**
 * @defgroup Eina_Future Eina Futures
 * @ingroup Eina_Promise
 * @brief Methods and structures dealing with #Eina_Future
 * @{
 */

/**
 * Cancels a future.
 *
 * This function will cancel the whole future chain immediately (it will not be schedule to the next mainloop pass)
 * and it will also cancel the promise linked against it. The #Eina_Future_Cb will be called
 * with an #Eina_Value typed as #EINA_VALUE_TYPE_ERROR, with its value set to @c ECANCELED
 * @param[in,out] f The future to cancel.
 */
EAPI void eina_future_cancel(Eina_Future *f) EINA_ARG_NONNULL(1);

/**
 * Flushes an #Eina_Future_Desc
 *
 * This function is mainly used by bindings to flush an #Eina_Future_Desc.
 * It will call the #Eina_Future_Cb with @c ENOMEM and zero the @p desc contents.
 *
 * @param[in,out] desc The #Eina_Future_Desc to flush, if @c NULL this is a noop.
 */
EAPI void eina_future_desc_flush(Eina_Future_Desc *desc);

/**
 * Flushes an #Eina_Future_Cb_Easy_Desc
 *
 * This function is mainly used by bindings to flush an #Eina_Future_Cb_Easy_Desc.
 * It will call the #Eina_Future_Error_Cb with @c ENOMEM, the #Eina_Future_Free_Cb and
 * zero the @p desc contents.
 *
 * @param[in,out] desc The #Eina_Future_Cb_Easy_Desc to flush, if @c NULL this is a noop.
 */
EAPI void eina_future_cb_easy_desc_flush(Eina_Future_Cb_Easy_Desc *desc);

/**
 * Creates a new #Eina_Value from a promise.
 *
 * This function creates a new #Eina_Value that will store an #Eina_Promise
 * in it. This function is useful for dealing with promises inside
 * an #Eina_Future_Cb. By returning a promise inside the #Eina_Value the
 * whole chain will wait until the promise is resolved in
 * order to continue its execution. Example:
 *
 * @code
 * static Eina_Value
 * _file_data_ready(const *data EINA_UNUSED, const Eina_Value v, const Eina_Future *dead EINA_UNUSED)
 * {
 *    const char *file_data;
 *    Eina_Promise *p;
 *    // It was not possible to fetch the file size.
 *    if (v.type == EINA_VALUE_TYPE_ERROR)
 *    {
 *       Eina_Error err;
 *       eina_value_get(&v, &err);
 *       fprintf(stderr, "Could not get the file data. Reason: %s\n", eina_error_msg_get(err));
 *       ecore_main_loop_quit();
 *       return v;
 *    }
 *    else if (v.type != EINA_VALUE_TYPE_STRING)
 *    {
 *      fprintf(stderr, "Expecting type '%s' - received '%s'\n", EINA_VALUE_TYPE_STRING->name, v.type->name);
 *      ecore_main_loop_quit();
 *      return v;
 *    }
 *
 *    eina_value_get(&v, &file_data);
 *    // count_words will count the words in the background and resolve the promise once it is over...
 *    p = count_words(file_data);
 *    return eina_promise_as_value(p);
 * }
 *
 * static Eina_Value
 * _word_count_ready(const *data EINA_UNUSED, const Eina_Value v, const Eina_Future *dead EINA_UNUSED)
 * {
 *    // The _word_count_ready will only be called once count_words() resolves/rejects the promise returned by _file_data_ready()
 *    int count;
 *    if (v.type == EINA_VALUE_TYPE_ERROR)
 *    {
 *       Eina_Error err;
 *       eina_value_get(&v, &err);
 *       fprintf(stderr, "Could not count the file words. Reason: %s\n", eina_error_msg_get(err));
 *       ecore_main_loop_quit();
 *       return v;
 *    }
 *    else if (v.type != EINA_VALUE_TYPE_INT)
 *    {
 *      fprintf(stderr, "Expecting type '%s' - received '%s'\n", EINA_VALUE_TYPE_INT->name, v.type->name);
 *      ecore_main_loop_quit();
 *      return v;
 *    }
 *    eina_value_get(&v, &count);
 *    printf("File word count %d\n", count);
 *    return v;
 * }
 *
 * void
 * file_operation(void)
 * {
 *    Eina_Future *f = get_file_data("/MyFile.txt");
 *    eina_future_chain(f, {.cb = _file_data_ready, .data = NULL},
 *                         {.cb = _word_count_ready, .data = NULL});
 * }
 * @endcode
 *
 * @param[in,out] p The promise object to wrap in a value.
 * @return An #Eina_Value. On error the value's type will be @c NULL.
 *
 * @note If an error happens the promise will be CANCELED.
 * @see eina_future_as_value()
 * @see eina_promise_reject()
 * @see eina_promise_resolve()
 */
EAPI Eina_Value eina_promise_as_value(Eina_Promise *p) EINA_ARG_NONNULL(1) EINA_WARN_UNUSED_RESULT;

/**
 * Creates an #Eina_Value from a future.
 *
 * This function is used for the same purposes as eina_promise_as_value(),
 * but receives an #Eina_Future instead.
 *
 * @param[in,out] f A future to create a Eina_Value from.
 * @return An Eina_Value. On error the value's type will be @c NULL.
 * @note If an error happens the future @p f will be CANCELED
 * @see eina_promise_as_value()
 */
EAPI Eina_Value eina_future_as_value(Eina_Future *f)EINA_ARG_NONNULL(1) EINA_WARN_UNUSED_RESULT;

/**
 * Creates a new future.
 *
 * This function creates a new future and can be used to report
 * that an operation has succeeded or failed using
 * eina_promise_resolve() or eina_promise_reject().
 *
 * Futures can also be canceled using eina_future_cancel(), which
 * will cause the whole chain to be canceled alongside with any pending promise.
 *
 * @note A promise can only have one future attached to it, calling
 * eina_future_new() on the same promise twice will
 * result in an error (@c NULL is returned) and the future
 * attached to the promise will be canceled!
 *
 * @param[in,out] p A promise used to attach a future. May not be @c NULL.
 * @return The future or @c NULL on error.
 * @note If an error happens this function will CANCEL the promise.
 * @see eina_promise_new()
 * @see eina_promise_reject()
 * @see eina_promise_resolve()
 * @see eina_future_cancel()
 */
EAPI Eina_Future *eina_future_new(Eina_Promise *p) EINA_ARG_NONNULL(1) EINA_WARN_UNUSED_RESULT;

/**
 * Creates a new future that is already resolved to a value.
 *
 * This function creates a new future with an already known value,
 * that will be resolved and dispatched by the given @p scheduler as
 * usual.
 *
 * This is a helper that behaves the same as eina_promise_new()
 * followed by eina_future_new() and then eina_promise_resolve().
 *
 * Futures can also be canceled using eina_future_cancel(), which will
 * cause the whole chain to be canceled alongside with any pending
 * promise.
 *
 * @param[in,out] scheduler The scheduler to use.
 * @param[in] value The value to be delivered. Note that the value
 * contents must survive this function scope, that is, do @b not use
 * stack allocated blobs, arrays, structures or types that keep
 * references to memory you give. Values will be automatically cleaned
 * up using @c eina_value_flush() once they are unused (no more future
 * or futures returned a new value).
 *
 * @return The future or @c NULL on error.
 *
 * @see eina_promise_new()
 * @see eina_future_new()
 * @see eina_promise_reject()
 * @see eina_promise_resolve()
 * @see eina_future_cancel()
 */
EAPI Eina_Future *eina_future_resolved(Eina_Future_Scheduler *scheduler, Eina_Value value) EINA_ARG_NONNULL(1);

/**
 * Creates a new future that is already rejected to a specified error.
 *
 * This function creates a new future with an already known error,
 * that will be resolved and dispatched by the given @p scheduler as
 * usual.
 *
 * This is a helper that behaves the same as eina_promise_new()
 * followed by eina_future_new() and then eina_promise_reject().
 *
 * Futures can also be canceled using eina_future_cancel(), which will
 * cause the whole chain to be canceled alongside with any pending
 * promise.
 *
 * @param[in,out] scheduler The scheduler to use.
 * @param[in] err An #Eina_Error value
 *
 * @return The future or @c NULL on error.
 *
 * @see eina_promise_new()
 * @see eina_future_new()
 * @see eina_promise_reject()
 * @see eina_promise_resolve()
 * @see eina_future_cancel()
 */
EAPI Eina_Future *eina_future_rejected(Eina_Future_Scheduler *scheduler, Eina_Error err);

/**
 * Register an #Eina_Future_Desc to be used when the future is resolved/rejected.
 *
 * With this function a callback and data is attached to the future and then
 * once it's resolved or rejected the callback will be informed.
 *
 * If during the future creation an error happens this function will return @c NULL,
 * and the Eina_Future_Desc::cb will be called reporting an error (@c EINVAL or @c ENOMEM),
 * so the user has a chance to free Eina_Future_Desc::data.
 *
 * In case a future in the chain is canceled, the whole chain will be canceled immediately
 * and the error @c ECANCELED will be reported.
 *
 * Here's a simple usage of this function.
 *
 * @code
 * static Eina_Value
 * _file_ready(const *data, const Eina_Value v, const Eina_Future *dead EINA_UNUSED)
 * {
 *    Ctx *ctx = data;
 *    // It was not possible to fetch the file size.
 *    if (v.type == EINA_VALUE_TYPE_ERROR)
 *    {
 *       Eina_Error err;
 *       eina_value_get(&v, &err);
 *       fprintf(stderr, "Could not read the file size. Reason: %s\n", eina_error_msg_get(err));
 *       ecore_main_loop_quit();
 *       return v;
 *    }
 *    else if (v.type != EINA_VALUE_TYPE_INT)
 *    {
 *      fprintf(stderr, "Expecting type '%s' - received '%s'\n", EINA_VALUE_TYPE_INT->name, v.type->name);
 *      ecore_main_loop_quit();
 *      return v;
 *    }
 *    eina_value_get(&v, &ctx->size);
 *    printf("File size is %d bytes\n", ctx->size);
 *    return v;
 * }
 *
 * void
 * file_operation(void)
 * {
 *    Eina_Future *f = get_file_size_async("/MyFile.txt");
 *    eina_future_then_from_desc(f, (const Eina_Future_Desc){.cb = _size_ready, .data = NULL});
 *    // There's a helper macro called eina_future_then() which simplifies the usage.
 *    // The code below has the same effect.
 *    // eina_future_then(f, _size_ready, NULL);
 * }
 * @endcode
 *
 * Although the code presented at `_size_ready()` is very simple, most of it
 * is just used to check the #Eina_Value type. In order
 * to avoid this type of code the function eina_future_cb_easy_from_desc()
 * was created. Please, check its documentation for more information.
 *
 * This function can also be used to create a future chain, making
 * it possible to execute the future result in a cascade order. When
 * using a future chain the #Eina_Value returned by a Eina_Future_Desc::cb
 * will be delivered to the next Eina_Future_Desc::cb in the chain.
 *
 * Here's an example:
 *
 * @code
 * static Eina_Value
 * _future_cb1(const *data EINA_UNUSED, const Eina_Value v)
 * {
 *    Eina_Value new_v;
 *    int i;
 *
 *    // There's no need to check the Eina_Value type since we're using eina_future_cb_easy()
 *    eina_value_get(&v, &i);
 *    printf("File size as int: %d\n", i);
 *    eina_value_setup(&new_v, EINA_VALUE_TYPE_STRING);
 *    // Convert the file size to string
 *    eina_value_convert(&v, &new_v);
 *    return new_v;
 * }
 *
 * static Eina_Value
 * _future_cb2(const *data EINA_UNUSED, const Eina_Value v)
 * {
 *    Eina_Value new_v;
 *    const char *file_size_str;
 *
 *    // There's no need to check the Eina_Value type since we're using eina_future_cb_easy()
 *    eina_value_get(&v, &file_size_str);
 *    printf("File size as string: %s\n", file_size_str);
 *    eina_value_setup(&new_v, EINA_VALUE_TYPE_DOUBLE);
 *    eina_value_convert(&v, &new_v);
 *    return new_v;
 * }
 *
 * static Eina_Value
 * _future_cb3(const *data EINA_UNUSED, const Eina_Value v)
 * {
 *    double d;
 *
 *    // There's no need to check the Eina_Value type since we're using eina_future_cb_easy()
 *    eina_value_get(&v, &d);
 *    printf("File size as double: %g\n", d);
 *    return v;
 * }
 *
 * static Eina_Value
 * _future_err(void *data EINA_UNUSED, Eina_Error err)
 * {
 *    // This function is called if future result type does not match or another error occurred
 *    Eina_Value new_v;
 *    eina_value_setup(&new_v, EINA_VALUE_TYPE_ERROR);
 *    eina_value_set(&new_v, err);
 *    fprintf(stderr, "Error during future process. Reason: %s\n", eina_error_msg_get(err));
 *    // Pass the error to the next future in the chain..
 *    return new_v;
 * }
 *
 * void chain(void)
 * {
 *   Eina_Future *f = get_file_size_async("/MyFile.txt");
 *   f = eina_future_then_easy(f, .success = _future_cb1, .success_type = EINA_VALUE_TYPE_INT);
 *   // _future_cb2 will be executed after _future_cb1()
 *   f = eina_future_then_easy(f, .success = _future_cb2, .success_type = EINA_VALUE_TYPE_STRING);
 *   // _future_cb3 will be executed after _future_cb2()
 *   f = eina_future_then_easy(f, .success = _future_cb3, .success_type = EINA_VALUE_TYPE_DOUBLE);
 *   // If an error happens _future_err will be called
 *   eina_future_then_easy(f, .error = _future_err);
 * }
 * @endcode
 *
 * Although it's possible to create a future chain using eina_future_then() and eina_future_then_from_desc()
 * there's a function that makes this task much easier, please check eina_future_chain_array() for more
 * information.
 * @note This example does manual conversion and print, however Eina offers
 * eina_future_cb_convert_to() and eina_future_cb_console_from_desc() to make those common case easier.
 *
 * @param[in,out] prev A future to link against
 * @param[in] desc A description struct containing the callback and data.
 * @return A new future or @c NULL on error.
 * @note If an error happens the whole future chain will CANCELED and
 * desc.cb will be called in order to free desc.data.
 * @see eina_future_new()
 * @see eina_future_then()
 * @see Eina_Future_Desc
 * @see eina_future_chain_array()
 * @see eina_future_chain()
 * @see eina_future_cb_console_from_desc()
 * @see eina_future_cb_easy_from_desc()
 * @see eina_future_cb_easy()
 * @see eina_future_cb_convert_to()
 * @see eina_future_cancel()
 * @see eina_future_then_easy()
 * @see eina_future_cb_log_from_desc()
 */
EAPI Eina_Future *eina_future_then_from_desc(Eina_Future *prev, const Eina_Future_Desc desc) EINA_ARG_NONNULL(1);

/**
 * Creates an Eina_Future_Desc that will log the previous future resolved value.
 *
 * This function can be used to quickly log the value that an Eina_Future_Desc::cb
 * is returning. The returned value will be passed to the next future in the chain without
 * modifications.
 *
 * There are some helper macros like eina_future_cb_log_dbg() which will automatically
 * fill the following fields:
 *
 * @li Eina_Future_Cb_Log_Desc::file: The `__FILE__` function will be used.
 * @li Eina_Future_Cb_Log_Desc::func: The `__func__` macro will be used.
 * @li Eina_Future_Cb_Log_Desc::level: `EINA_LOG_LEVEL_DBG` will be used.
 * @li Eina_Future_Cb_Log_Desc::domain: `EINA_LOG_DOMAIN_DEFAULT` will be used.
 * @li Eina_Future_Cb_Log_Desc::line: The `__LINE__` macro will be used.
 *
 * @param[in] desc The description data to be used.
 * @return An #Eina_Future_Desc
 *
 * @see Eina_Future_Cb_Log_Desc
 * @see eina_future_then()
 * @see eina_future_chain()
 * @see eina_future_cb_log_dbg()
 * @see eina_future_cb_log_crit()
 * @see eina_future_cb_log_err()
 * @see eina_future_cb_log_info()
 * @see eina_future_cb_log_warn()
 * @see eina_future_cb_console_from_desc()
 */
EAPI Eina_Future_Desc eina_future_cb_log_from_desc(const Eina_Future_Cb_Log_Desc desc) EINA_WARN_UNUSED_RESULT;

/**
 * Creates a future chain.
 *
 * This behaves exactly like eina_future_then_from_desc(), but makes it easier to create future chains.
 *
 * If during the future chain creation an error happens this function will return @c NULL,
 * and the Eina_Future_Desc::cb from the @p descs array will be called reporting an error (`EINVAL` or `ENOMEM`),
 * so the user has a chance to free Eina_Future_Desc::data.
 *
 * Just like eina_future_then_from_desc(), the value returned by a Eina_Future_Desc::cb callback will
 * be delivered to the next Eina_Future_Desc::cb in the chain.
 *
 * In case a future in the chain is canceled, the whole chain will be canceled immediately
 * and the error `ECANCELED` will be reported.
 *
 * Here's an example:
 *
 * @code
 * // callbacks code....
 *
 * Eina_Future* chain(void)
 * {
 *   Eina_Future *f = get_file_size_async("/MyFile.txt");
 *   return eina_future_chain(f, eina_future_cb_easy(_future_cb1, _future_err, NULL, EINA_VALUE_TYPE_INT, NULL),
 *                               eina_future_cb_easy(_future_cb2, _future_err, NULL, EINA_VALUE_TYPE_STRING, NULL),
 *                               eina_future_cb_easy(_future_cb3, _future_err, NULL, EINA_VALUE_TYPE_DOUBLE, NULL),
 *                               {.cb = _future_cb4, .data = NULL });
 * }
 * @endcode
 *
 * @param[in,out] prev The previous future
 * @param[in] descs An array of descriptions.
                    The last element of the array must have the Eina_Future_Desc::cb set to @c NULL
 * @return A future or @c NULL on error.
 * @note If an error happens the whole future chain will CANCELED and
 * desc.cb will be called in order to free desc.data.
 * @see eina_future_new()
 * @see eina_future_then()
 * @see Eina_Future_Desc
 * @see eina_future_chain()
 * @see eina_future_cb_ignore_error()
 * @see eina_future_cb_console_from_desc()
 * @see eina_future_cb_log_from_desc()
 * @see eina_future_cb_easy_from_desc()
 * @see eina_future_cb_easy()
 * @see eina_future_then_from_desc()
 * @see eina_future_then_easy()
 * @see eina_future_cb_convert_to()
 */
EAPI Eina_Future *eina_future_chain_array(Eina_Future *prev, const Eina_Future_Desc descs[]) EINA_ARG_NONNULL(1, 2);


/**
 * Wrapper around eina_future_chain_array() and eina_future_cb_easy_from_desc()
 *
 * This functions makes it easier to use  eina_future_chain_array() with eina_future_cb_easy_from_desc(),
 * check the macro eina_future_chain_easy() for a syntax sugar.
 *
 *
 * @param[in,out] prev The previous future
 * @param[in] descs An array of descriptions. The last element of the array must have the Eina_Future_Desc::cb set to @c NULL
 * @return A future or @c NULL on error.
 * @note If an error happens the whole future chain will CANCELED and
 * desc.cb will be called in order to free desc.data.
 * @see eina_future_chain_easy()
 * @see eina_future_chain()
 * @see eina_future_cb_easy()
 * @see eina_future_chain_array()
 * @see eina_future_cb_easy_from_desc()
 */
EAPI Eina_Future *eina_future_chain_easy_array(Eina_Future *prev, const Eina_Future_Cb_Easy_Desc descs[]) EINA_ARG_NONNULL(1, 2);

/**
 * Creates an #Eina_Future_Desc that will print the previous future's resolved value.
 *
 * This function can be used to quickly inspect the value that an Eina_Future_Desc::cb
 * is returning. The returned value will be passed to the next future in the chain without
 * modifications.
 *
 * There's also a helper macro called eina_future_cb_console() which makes this
 * function easier to use.
 *
 * Example:
 *
 * @code
 *
 * eina_future_chain(a_future, {.cb = cb1, .data = NULL},
 *                             //Inspect the cb1 value and pass to cb2 without modifications
 *                             eina_future_cb_console("cb1 value:"),
 *                             {.cb = cb2, .data = NULL},
 *                             //Inspect the cb2 value
 *                             eina_future_cb_console("cb2 value:", " cb2 value suffix\n"))
 * @endcode
 *
 * @param[in] desc Description object with contextual information.
 * @return An #Eina_Future_Desc
 *
 * The description object, @p desc, can (optionally) include a prefix, suffix,
 * filename and function name. If these are @c NULL, empty strings ("") are used
 * instead.  If @p desc->suffix is provided, the '\\n' should be provided to ensure
 * the printed string ends with a line feed.
 *
 * @see eina_future_then()
 * @see Eina_Future_Desc
 * @see eina_future_chain()
 * @see eina_future_cb_easy_from_desc()
 * @see eina_future_cb_easy()
 * @see eina_future_then_from_desc()
 * @see eina_future_then_easy()
 * @see eina_future_cb_console()
 * @see eina_future_cb_ignore_error()
 * @see eina_future_cb_log_from_desc()
 */
EAPI Eina_Future_Desc eina_future_cb_console_from_desc(const Eina_Future_Cb_Console_Desc desc) EINA_WARN_UNUSED_RESULT;

/**
 * Returns an #Eina_Future_Desc that ignores an error.
 *
 * This function may be used if one wants to ignore an error. If the
 * specified error happens an #EINA_VALUE_EMPTY will be delivered to the
 * next future in the chain.
 *
 * @param[in] err The error to be ignored.
 * @return A future descriptor to be used with eina_future_then() or eina_future_chain()
 */
EAPI Eina_Future_Desc eina_future_cb_ignore_error(Eina_Error err);

/**
 * Creates an #Eina_Future_Desc which will convert the received eina value to a given type.
 *
 * @param[in] type The #Eina_Value_Type to convert to.
 * @return An #Eina_Future_Desc
 * @see eina_future_then()
 * @see Eina_Future_Desc
 * @see eina_future_chain()
 * @see eina_future_cb_easy_from_desc()
 * @see eina_future_cb_easy()
 * @see eina_future_then_from_desc()
 * @see eina_future_then_easy()
 */
EAPI Eina_Future_Desc eina_future_cb_convert_to(const Eina_Value_Type *type);

/**
 * Creates an #Eina_Future_Desc based on an #Eina_Future_Cb_Easy_Desc.
 *
 * This function aims to be used in conjunction with eina_future_chain(),
 * eina_future_then_from_desc() and friends and its main objective is to simplify
 * error handling and #Eina_Value type checks.
 * It uses three callbacks to inform the user about the future's
 * result and life cycle. They are:
 *
 * @li Eina_Future_Cb_Easy_Desc::success: This callback is called when
 * the future execution was successful, that is, no errors occurred and
 * the result type matches Eina_Future_Cb_Easy_Desc::success_type. In case
 * Eina_Future_Cb_Easy_Desc::success_type is @c NULL, this function will
 * only be called if the future did not report an error. The value returned
 * by this function will be propagated to the next future in the chain (if any).
 *
 * @li Eina_Future_Cb_Easy_Desc::error: This callback is called when
 * the future result is an error or Eina_Future_Cb_Easy_Desc::success_type
 * does not match the future result type. The value returned
 * by this function will be propagated to the next future in the chain (if any).
 *
 * @li Eina_Future_Cb_Easy_Desc::free: Called after the future was freed and any resources
 * allocated must be freed at this point. This callback is always called.
 *
 * Check the example below for a sample usage:
 *
 * @code
 * static Eina_Value
 * _file_size_ok(void *data, Eina_Value v)
 * {
 *   Ctx *ctx = data;
 *   // Since an Eina_Future_Cb_Easy_Desc::success_type was provided, there's no need to check the value type
 *   int s;
 *   eina_value_get(&v, &s);
 *   printf("File size is %d bytes\n", s);
 *   ctx->file_size = s;
 *   return v;
 * }
 *
 * static Eina_Value
 * _file_size_err(void *data, Eina_Error err)
 * {
 *   fprintf(stderr, "Could not read the file size. Reason: %s\n", eina_error_msg_get(err));
 *   // Stop propagating the error.
 *   return EINA_VALUE_EMPTY;
 * }
 *
 * static void
 * _future_freed(void *data, const Eina_Future dead)
 * {
 *   Ctx *ctx = data;
 *   printf("Future %p deleted\n", dead);
 *   ctx->file_size_handler_cb(ctx->file_size);
 *   free(ctx);
 * }
 *
 * void do_work(File_Size_Handler_Cb cb)
 * {
 *   Ctx *ctx = malloc(sizeof(Ctx));
 *   ctx->f = get_file_size("/tmp/todo.txt");
 *   ctx->file_size = -1;
 *   ctx->file_size_handler_cb = cb;
 *   eina_future_then_easy(f, _file_size_ok, _file_size_err, _future_freed, EINA_VALUE_TYPE_INT, ctx);
 * }
 * @endcode
 *
 * @param[in] desc The easy callback's description.
 * @return An #Eina_Future_Desc
 *
 * @see eina_future_chain()
 * @see eina_future_then()
 * @see eina_future_cb_easy()
 */
EAPI Eina_Future_Desc eina_future_cb_easy_from_desc(const Eina_Future_Cb_Easy_Desc desc) EINA_WARN_UNUSED_RESULT;

/**
 * Creates an all promise.
 *
 * Creates a promise that is resolved once all the futures
 * from the @p array are resolved.
 * The promise is resolved with an #Eina_Value type array which
 * contains #EINA_VALUE_TYPE_VALUE elements. The result array is
 * ordered according to the @p array argument. Example:
 *
 * @code
 * static const char *
 * _get_operation_name_by_index(int idx)
 * {
 *   switch (idx)
 *   {
 *      case 0: return "Get file data";
 *      case 1: return "Get file size";
 *      default: return "sum";
 *   }
 * }
 *
 * static Eina_Value
 * _all_cb(const void *data EINA_UNUSED, const Eina_Value array, const Eina_Future *dead EINA_UNUSED)
 * {
 *    Eina_Error err;
 *    unsigned int i, len;
 *
 *    if (array.type == EINA_VALUE_TYPE_ERROR)
 *     {
 *       eina_value_get(&array, &err);
 *       fprintf(stderr, "Could not complete all operations. Reason: %s\n", eina_error_msg_get(err));
 *       return array;
 *     }
 *    len = eina_value_array_count(&array);
 *    for (i = 0; i < len; i++)
 *     {
 *       Eina_Value v;
 *       eina_value_array_get(&array, i, &v);
 *       if (v.type == EINA_VALUE_TYPE_ERROR)
 *        {
 *          eina_value_get(&v, &err);
 *          fprintf(stderr, "Could not complete operation '%s'. Reason: %s\n", _get_operation_name_by_index(i), eina_error_msg_get(err));
 *          continue;
 *        }
 *       if (!i)
 *        {
 *           const char *msg;
 *           if (v.type != EINA_VALUE_TYPE_STRING)
 *           {
 *             fprintf(stderr, "Operation %s expects '%s' - received '%s'\n", _get_operation_name_by_index(i), EINA_VALUE_TYPE_STRING->name, v.type->name);
 *             continue;
 *           }
 *           eina_value_get(&v, &msg);
 *           printf("File content:%s\n", msg);
 *        }
 *       else if (i == 1)
 *        {
 *           int i;
 *           if (v.type != EINA_VALUE_TYPE_INT)
 *           {
 *             fprintf(stderr, "Operation %s expects '%s' - received '%s'\n", _get_operation_name_by_index(i), EINA_VALUE_TYPE_INT->name, v.type->name);
 *             continue;
 *           }
 *           eina_value_get(&v, &i);
 *           printf("File size: %d\n", i);
 *        }
 *        else
 *        {
 *           double p;
 *           if (v.type != EINA_VALUE_TYPE_DOUBLE)
 *           {
 *             fprintf(stderr, "Operation %s expects '%s' - received '%s'\n", _get_operation_name_by_index(i), EINA_VALUE_TYPE_DOUBLE->name, v.type->name);
 *             continue;
 *           }
 *           eina_value_get(&v, &p);
 *           printf("50 places of PI: %f\n", p);
 *        }
 *     }
 *    return array;
 * }
 *
 * void func(void)
 * {
 *   Eina_Future *f1, *f2, *f3, f_all;
 *
 *   f1 = read_file("/tmp/todo.txt");
 *   f2 = get_file_size("/tmp/file.txt");
 *   // calculates 50 places of PI
 *   f3 = calc_pi(50);
 *   f_all = eina_future_all(f1, f2, f3);
 *   eina_future_then(f_all, _all_cb, NULL);
 * }
 * @endcode
 *
 * @param[in,out] array An array of futures, terminated with #EINA_FUTURE_SENTINEL.
 * @return A promise or @c NULL on error.
 * @note On error all the futures will be CANCELED.
 * @see eina_future_all_array()
 */
EAPI Eina_Promise *eina_promise_all_array(Eina_Future *array[]) EINA_ARG_NONNULL(1) EINA_WARN_UNUSED_RESULT;

/**
 * Creates an all promise from an iterator.
 *
 * Creates a promise that is resolved once all the futures
 * from the @p iterator are resolved.
 * The promise is resolved with an #Eina_Value type array which
 * contains #EINA_VALUE_TYPE_VALUE elements. The result array is
 * ordered according to the @p iterator order.
 *
 * @param[in] iterator An iterator of futures. Will be destroyed after the call.
 * @return A promise or @c NULL on error.
 * @note On error all the futures will be CANCELED.
 * @see eina_future_all_iterator()
 */
EAPI Eina_Promise *eina_promise_all_iterator(Eina_Iterator *iterator) EINA_ARG_NONNULL(1) EINA_WARN_UNUSED_RESULT;

/**
 * Creates a race promise.
 *
 * Creates a promise that resolves when a future from the @p array
 * is completed. The remaining futures will be canceled with the
 * error code `ECANCELED`
 *
 * The resulting value is an #EINA_VALUE_TYPE_STRUCT with two fields:
 *
 * @li A field named @c value containing an #Eina_Value with the result itself.
 * @li A field named @c index containing the index of the completed
 * function relative to the @p array.
 *
 * Example:
 *
 * @code
 * static const char *
 * _get_operation_name_by_index(int idx)
 * {
 *   switch (idx)
 *   {
 *      case 0: return "Get file data";
 *      case 1: return "Get file size";
 *      default: return "sum";
 *   }
 * }
 *
 * static Eina_Value
 * _race_cb(const void *data EINA_UNUSED, const Eina_Value v)
 * {
 *    unsigned int i;
 *    Eina_Value result;
 *    Eina_Error err;
 *    Eina_Value_Struct *st;
 *
 *     // No need to check for the 'v' type. eina_future_cb_easy() did that for us.
 *     // However we should check if the struct has the correct description
 *     st = eina_value_memory_get(&v);
 *     if (st->desc != EINA_PROMISE_RACE_STRUCT_DESC)
 *      {
 *         fprintf(stderr, "Eina_Value is not a race struct\n");
 *         return v;
 *      }
 *     eina_value_struct_get(&v, "index", &i);
 *     // Get the operation result
 *     eina_value_struct_get(&v, "value", &result);
 *     if (!i)
 *      {
 *        const char *msg;
 *        if (result.type != EINA_VALUE_TYPE_STRING)
 *          fprintf(stderr, "Operation %s expects '%s' - received '%s'\n", _get_operation_name_by_index(i), EINA_VALUE_TYPE_STRING->name, result.type->name);
 *        else
 *        {
 *          eina_value_get(&result, &msg);
 *          printf("File content:%s\n", msg);
 *        }
 *      }
 *     else if (i == 1)
 *       {
 *         int i;
 *         if (result.type != EINA_VALUE_TYPE_INT)
 *           fprintf(stderr, "Operation %s expects '%s' - received '%s'\n", _get_operation_name_by_index(i), EINA_VALUE_TYPE_INT->name, v.type->name);
 *         else
 *         {
 *           eina_value_get(&result, &i);
 *           printf("File size: %d\n", i);
 *         }
 *       }
 *      else
 *       {
 *         double p;
 *         if (result.type != EINA_VALUE_TYPE_DOUBLE)
 *            fprintf(stderr, "Operation %s expects '%s' - received '%s'\n", _get_operation_name_by_index(i), EINA_VALUE_TYPE_DOUBLE->name, result.type->name);
 *         else
 *          {
 *            eina_value_get(&result, &p);
 *            printf("50 places of PI: %f\n", p);
 *          }
 *       }
 *     eina_value_flush(&result);
 *     return v;
 * }
 *
 * static Eina_Value
 * _race_err(void *data, Eina_Error err)
 * {
 *    fprintf(stderr, "Could not complete the race future. Reason: %s\n", eina_error_msg_get(err));
 *    return EINA_VALUE_EMPTY;
 * }
 *
 * void func(void)
 * {
 *   static const *Eina_Future[] = {NULL, NULL, NULL, NULL};
 *   Eina_List *l = NULL;
 *
 *   futures[0] = read_file("/tmp/todo.txt");
 *   futures[1] = get_file_size("/tmp/file.txt");
 *   // calculates 50 places of PI
 *   futures[2] = calc_pi(50);
 *   f_race = eina_future_race_array(futures);
 *   eina_future_then_easy(f_race, _race_cb, _race_err, NULL, EINA_VALUE_TYPE_STRUCT, NULL);
 * }
 * @endcode
 *
 * @param[in,out] array An array of futures, terminated by #EINA_FUTURE_SENTINEL.
 * @return A promise or @c NULL on error.
 * @note On error all the futures will be CANCELED.
 * @see eina_future_race_array()
 * @see _Eina_Future_Race_Result
 */
EAPI Eina_Promise *eina_promise_race_array(Eina_Future *array[]) EINA_ARG_NONNULL(1) EINA_WARN_UNUSED_RESULT;

/**
 * @struct _Eina_Future_Race_Result
 * The struct that is used to store the race result.
 *
 * When using eina_promise_race_array() and friends, the future result
 * will be reported as a struct. The values can be obtained using
 * eina_value_struct_get() or one could access the struct directly
 * such as this example:
 *
 * @code
 * static Eina_Value
 * _race_cb(const void *data EINA_UNUSED, const Eina_Value v)
 * {
 *    //code...
 *    Eina_Value_Struct st;
 *    Eina_Future_Race_Result *rr;
 *    eina_value_get(v, &st);
 *    rr = st.memory;
 *    printf("Winning future index: %u\n", rr->index);
 *    //more code..
 *    return v;
 * }
 * @endcode
 *
 * @see eina_promise_race_array()
 * @see eina_future_race_array()
 * @see eina_promise_race()
 * @see eina_future_race()
 * @see EINA_PROMISE_RACE_STRUCT_DESC
 */
struct _Eina_Future_Race_Result {
   /**
    * The race result.
    */
   Eina_Value value;
   /**
    * The future index that won the race.
    */
   unsigned int index;
};

/**
 * @var const Eina_Value_Struct_Desc *EINA_PROMISE_RACE_STRUCT_DESC
 *
 * A pointer to the race struct description, which
 * is used by eina_promise_race_array().
 *
 * This struct contains two members:
 * @li @c value: An #EINA_VALUE_TYPE_VALUE that contains the future result that won the race.
 * @li @c index: An #EINA_VALUE_TYPE_UINT that contains the future index that won the race.
 *
 * @see eina_promise_race_array()
 * @see _Eina_Future_Race_Result
 */
EAPI extern const Eina_Value_Struct_Desc *EINA_PROMISE_RACE_STRUCT_DESC;

/**
 * Creates a future that will be resolved once all futures from @p array is resolved.
 * This is a helper over eina_promise_all_array()
 *
 * @param[in,out] array A future array, must be terminated with #EINA_FUTURE_SENTINEL.
 * @return A future.
 * @see eina_promise_all_array()
 * @see EINA_FUTURE_SENTINEL
 */
static inline Eina_Future *
eina_future_all_array(Eina_Future *array[])
{
   Eina_Promise *p = eina_promise_all_array(array);
   if (!p) return NULL;
   return eina_future_new(p);
}

/**
 * Creates a future that will be resolved once all futures from @p iterator are resolved.
 * This is a helper over eina_promise_all_iterator()
 *
 * @param[in] iterator An iterator containing futures. Will be destroyed on exit of the function.
 * @return A future.
 * @see eina_promise_all_iterator()
 */
static inline Eina_Future *
eina_future_all_iterator(Eina_Iterator *iterator)
{
   Eina_Promise *p = eina_promise_all_iterator(iterator);
   if (!p) return NULL;
   return eina_future_new(p);
}

/**
 * Creates a future that will be resolved once a future @p array is resolved.
 * This is a helper over eina_promise_race_array()
 *
 * @param[in,out] array A future array, must be terminated with #EINA_FUTURE_SENTINEL
 * @return A future.
 * @see eina_promise_race_array()
 * @see EINA_FUTURE_SENTINEL
 */
static inline Eina_Future *
eina_future_race_array(Eina_Future *array[])
{
   Eina_Promise *p = eina_promise_race_array(array);
   if (!p) return NULL;
   return eina_future_new(p);
}

/**
 * Used by eina_promise_race_array() and eina_promise_all_array() and
 * friends to flag the end of the array.
 *
 * @see eina_promise_race_array()
 * @see eina_promise_all_array()
 */
#define EINA_FUTURE_SENTINEL ((void *)(unsigned long)-1)

/**
 * A syntactic sugar over eina_promise_race_array().
 * Usage:
 * @code
 * promise = eina_promise_race(future1, future2, future3, future4);
 * @endcode
 * @see eina_promise_race_array()
 */
#define eina_promise_race(...) eina_promise_race_array((Eina_Future *[]){__VA_ARGS__, EINA_FUTURE_SENTINEL})
/**
 * A syntactic sugar over eina_future_race_array().
 * Usage:
 * @code
 * future = eina_future_race(future1, future2, future3, future4);
 * @endcode
 * @see eina_future_race_array()
 */
#define eina_future_race(...) eina_future_race_array((Eina_Future *[]){__VA_ARGS__, EINA_FUTURE_SENTINEL})
/**
 * A syntactic sugar over eina_future_all_array().
 * Usage:
 * @code
 * future = eina_future_all(future1, future2, future3, future4);
 * @endcode
 * @see eina_future_all_array()
 */
#define eina_future_all(...) eina_future_all_array((Eina_Future *[]){__VA_ARGS__, EINA_FUTURE_SENTINEL})
/**
 * A syntactic sugar over eina_promise_all_array().
 * Usage:
 * @code
 * promise = eina_promise_all(future1, future2, future3, future4);
 * @endcode
 * @see eina_promise_all_array()
 */
#define eina_promise_all(...) eina_promise_all_array((Eina_Future *[]){__VA_ARGS__, EINA_FUTURE_SENTINEL})
/**
 * A syntactic sugar over eina_future_cb_easy_from_desc().
 * Usage:
 * @code
 * future_desc = eina_future_cb_easy(_success_cb, _error_cb, _free_cb, EINA_VALUE_TYPE_INT, my_data);
 * @endcode
 * @see eina_future_cb_easy_from_desc()
 */
#define eina_future_cb_easy(...) eina_future_cb_easy_from_desc((Eina_Future_Cb_Easy_Desc){__VA_ARGS__})
/**
 * A syntactic sugar over eina_future_chain_array().
 * Usage:
 * @code
 * future = eina_future_chain(future, {.cb = _my_cb, .data = my_data}, {.cb = _my_another_cb, .data = NULL});
 * @endcode
 * @see eina_future_chain_array()
 */
#define eina_future_chain(_prev, ...) eina_future_chain_array(_prev, (Eina_Future_Desc[]){__VA_ARGS__, {.cb = NULL, .data = NULL}})
/**
 * A syntactic sugar over eina_future_then_from_desc().
 * Usage:
 * @code
 * future = eina_future_then(future, _my_cb, my_data);
 * @endcode
 * @see eina_future_then_from_desc()
 * @see eina_future_then_easy()
 */
#define eina_future_then(_prev, ...) eina_future_then_from_desc(_prev, (Eina_Future_Desc){__VA_ARGS__})
/**
 * A syntactic sugar over eina_future_cb_console_from_desc().
 * Usage:
 * @code
 * desc = eina_future_cb_console(.prefix = "prefix", .suffix = "suffix");
 * @endcode
 * @see eina_future_cb_console_from_desc()
 */
#define eina_future_cb_console(...) eina_future_cb_console_from_desc((Eina_Future_Cb_Console_Desc){__VA_ARGS__})

/**
 * A syntactic sugar over eina_future_cb_log_from_desc().
 *
 * This macro will set the following fields of the #Eina_Future_Cb_Log_Desc:
 *
 * @li Eina_Future_Cb_Log_Desc::file: The `__FILE__` function will be used.
 * @li Eina_Future_Cb_Log_Desc::func: The `__func__` macro will be used.
 * @li Eina_Future_Cb_Log_Desc::level: `EINA_LOG_LEVEL_DBG` will be used.
 * @li Eina_Future_Cb_Log_Desc::domain: `EINA_LOG_DOMAIN_DEFAULT` will be used.
 * @li Eina_Future_Cb_Log_Desc::line: The `__LINE__` macro will be used.
 *
 * Usage:
 * @code
 * desc = eina_future_cb_log_dbg(.prefix = "prefix", .suffix = "suffix");
 * @endcode
 * @see eina_future_cb_log_from_desc()
 */
#define eina_future_cb_log_dbg(_prefix, _suffix)                        \
  eina_future_cb_log_from_desc((Eina_Future_Cb_Log_Desc){_prefix, _suffix, __FILE__, \
         __func__, EINA_LOG_LEVEL_DBG, EINA_LOG_DOMAIN_DEFAULT, __LINE__})

/**
 * A syntactic sugar over eina_future_cb_log_from_desc().
 *
 * This macro will set the following fields of the Eina_Future_Cb_Log_Desc:
 *
 * @li Eina_Future_Cb_Log_Desc::file: The __FILE__ function will be used.
 * @li Eina_Future_Cb_Log_Desc::func: The __func__ macro will be used.
 * @li Eina_Future_Cb_Log_Desc::level: EINA_LOG_LEVEL_CRITICAL will be used.
 * @li Eina_Future_Cb_Log_Desc::domain: EINA_LOG_DOMAIN_DEFAULT will be used.
 * @li Eina_Future_Cb_Log_Desc::line: The __LINE__ macro will be used.
 *
 * Usage:
 * @code
 * desc = eina_future_cb_log_crit(.prefix = "prefix", .suffix = "suffix");
 * @endcode
 * @see eina_future_cb_log_from_desc()
 */
#define eina_future_cb_log_crit(_prefix, _suffix)                       \
  eina_future_cb_log_from_desc((Eina_Future_Cb_Log_Desc){_prefix, _suffix, __FILE__, \
         __func__, EINA_LOG_LEVEL_CRITICAL, EINA_LOG_DOMAIN_DEFAULT, __LINE__})

/**
 * A syntactic sugar over eina_future_cb_log_from_desc().
 *
 * This macro will set the following fields of the Eina_Future_Cb_Log_Desc:
 *
 * @li Eina_Future_Cb_Log_Desc::file: The __FILE__ function will be used.
 * @li Eina_Future_Cb_Log_Desc::func: The __func__ macro will be used.
 * @li Eina_Future_Cb_Log_Desc::level: EINA_LOG_LEVEL_ERR will be used.
 * @li Eina_Future_Cb_Log_Desc::domain: EINA_LOG_DOMAIN_DEFAULT will be used.
 * @li Eina_Future_Cb_Log_Desc::line: The __LINE__ macro will be used.
 *
 * Usage:
 * @code
 * desc = eina_future_cb_log_err(.prefix = "prefix", .suffix = "suffix");
 * @endcode
 * @see eina_future_cb_log_from_desc()
 */
#define eina_future_cb_log_err(_prefix, _suffix)                        \
  eina_future_cb_log_from_desc((Eina_Future_Cb_Log_Desc){_prefix, _suffix, __FILE__, \
         __func__, EINA_LOG_LEVEL_ERR, EINA_LOG_DOMAIN_DEFAULT, __LINE__})

/**
 * A syntactic sugar over eina_future_cb_log_from_desc().
 *
 * This macro will set the following fields of the Eina_Future_Cb_Log_Desc:
 *
 * @li Eina_Future_Cb_Log_Desc::file: The __FILE__ function will be used.
 * @li Eina_Future_Cb_Log_Desc::func: The __func__ macro will be used.
 * @li Eina_Future_Cb_Log_Desc::level: EINA_LOG_LEVEL_INFO will be used.
 * @li Eina_Future_Cb_Log_Desc::domain: EINA_LOG_DOMAIN_DEFAULT will be used.
 * @li Eina_Future_Cb_Log_Desc::line: The __LINE__ macro will be used.
 *
 * Usage:
 * @code
 * desc = eina_future_cb_log_info(.prefix = "prefix", .suffix = "suffix");
 * @endcode
 * @see eina_future_cb_log_from_desc()
 */
#define eina_future_cb_log_info(_prefix, _suffix)                       \
  eina_future_cb_log_from_desc((Eina_Future_Cb_Log_Desc){_prefix, _suffix, __FILE__, \
         __func__, EINA_LOG_LEVEL_INFO, EINA_LOG_DOMAIN_DEFAULT, __LINE__})

/**
 * A syntactic sugar over eina_future_cb_log_from_desc().
 *
 * This macro will set the following fields of the Eina_Future_Cb_Log_Desc:
 *
 * @li Eina_Future_Cb_Log_Desc::file: The __FILE__ function will be used.
 * @li Eina_Future_Cb_Log_Desc::func: The __func__ macro will be used.
 * @li Eina_Future_Cb_Log_Desc::level: EINA_LOG_LEVEL_WARN will be used.
 * @li Eina_Future_Cb_Log_Desc::domain: EINA_LOG_DOMAIN_DEFAULT will be used.
 * @li Eina_Future_Cb_Log_Desc::line: The __LINE__ macro will be used.
 *
 * Usage:
 * @code
 * desc = eina_future_cb_log_warn(.prefix = "prefix", .suffix = "suffix");
 * @endcode
 * @param _prefix PREFIX
 * @param _suffix SUFFIX
 * @returns SOMETHING
 * @see eina_future_cb_log_from_desc()
 */
#define eina_future_cb_log_warn(_prefix, _suffix)                       \
  eina_future_cb_log_from_desc((Eina_Future_Cb_Log_Desc){_prefix, _suffix, __FILE__, \
         __func__, EINA_LOG_LEVEL_WARN, EINA_LOG_DOMAIN_DEFAULT, __LINE__})

/**
 * A syntactic sugar over eina_future_then() and eina_future_cb_easy().
 *
 * Usage:
 * @code
 * f = eina_future_then_easy(f, .success = _success_cb, .success_type = EINA_VALUE_TYPE_DOUBLE, .data = NULL, );
 * @endcode
 * @see eina_future_then_from_desc()
 * @see eina_future_easy()
 * @see eina_future_then()
 * @see eina_future_cb_easy_from_desc()
 */
#define eina_future_then_easy(_prev, ...) eina_future_then_from_desc(_prev, eina_future_cb_easy(__VA_ARGS__))

/**
 * A syntactic sugar over eina_future_chain() and eina_future_cb_easy().
 *
 * Usage:
 * @code
 * f = eina_future_chain_easy(f, {.success = _success_cb, .success_type = EINA_VALUE_TYPE_DOUBLE, .data = NULL},
 *                               { .success = _success2_cb }, {.error = error_cb});
 * @endcode
 * @see eina_future_chain_array()
 * @see eina_future_easy()
 * @see eina_future_chain_easy_array()
 * @see eina_future_cb_easy_from_desc()
 */
#define eina_future_chain_easy(_prev, ...) eina_future_chain_easy_array(_prev, (Eina_Future_Cb_Easy_Desc[]) {__VA_ARGS__, {NULL, NULL, NULL, NULL, NULL}})

/**
 * @}
 */

#ifdef __cplusplus
}
#endif
#endif