quick_xml/reader/
mod.rs

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
//! Contains high-level interface for a pull-based XML parser.

#[cfg(feature = "encoding")]
use encoding_rs::Encoding;
use std::io;
use std::ops::Range;

use crate::encoding::Decoder;
use crate::errors::{Error, SyntaxError};
use crate::events::Event;
use crate::parser::{ElementParser, Parser, PiParser};
use crate::reader::state::ReaderState;

/// A struct that holds a parser configuration.
///
/// Current parser configuration can be retrieved by calling [`Reader::config()`]
/// and changed by changing properties of the object returned by a call to
/// [`Reader::config_mut()`].
///
/// [`Reader::config()`]: crate::reader::Reader::config
/// [`Reader::config_mut()`]: crate::reader::Reader::config_mut
#[derive(Debug, Clone, PartialEq, Eq)]
#[cfg_attr(feature = "arbitrary", derive(arbitrary::Arbitrary))]
#[cfg_attr(feature = "serde-types", derive(serde::Deserialize, serde::Serialize))]
#[non_exhaustive]
pub struct Config {
    /// Whether unmatched closing tag names should be allowed. Unless enabled,
    /// in case of a dangling end tag, the [`Error::IllFormed(UnmatchedEndTag)`]
    /// is returned from read methods.
    ///
    /// When set to `true`, it won't check if a closing tag has a corresponding
    /// opening tag at all. For example, `<a></a></b>` will be permitted.
    ///
    /// Note that the emitted [`End`] event will not be modified if this is enabled,
    /// ie. it will contain the data of the unmatched end tag.
    ///
    /// Note, that setting this to `true` will lead to additional allocates that
    /// needed to store tag name for an [`End`] event.
    ///
    /// Default: `false`
    ///
    /// [`Error::IllFormed(UnmatchedEndTag)`]: crate::errors::IllFormedError::UnmatchedEndTag
    /// [`End`]: crate::events::Event::End
    pub allow_unmatched_ends: bool,

    /// Whether comments should be validated. If enabled, in case of invalid comment
    /// [`Error::IllFormed(DoubleHyphenInComment)`] is returned from read methods.
    ///
    /// When set to `true`, every [`Comment`] event will be checked for not
    /// containing `--`, which [is not allowed] in XML comments. Most of the time
    /// we don't want comments at all so we don't really care about comment
    /// correctness, thus the default value is `false` to improve performance.
    ///
    /// Default: `false`
    ///
    /// [`Error::IllFormed(DoubleHyphenInComment)`]: crate::errors::IllFormedError::DoubleHyphenInComment
    /// [`Comment`]: crate::events::Event::Comment
    /// [is not allowed]: https://www.w3.org/TR/xml11/#sec-comments
    pub check_comments: bool,

    /// Whether mismatched closing tag names should be detected. If enabled, in
    /// case of mismatch the [`Error::IllFormed(MismatchedEndTag)`] is returned from
    /// read methods.
    ///
    /// Note, that start and end tags [should match literally][spec], they cannot
    /// have different prefixes even if both prefixes resolve to the same namespace.
    /// The XML
    ///
    /// ```xml
    /// <outer xmlns="namespace" xmlns:p="namespace">
    /// </p:outer>
    /// ```
    ///
    /// is not valid, even though semantically the start tag is the same as the
    /// end tag. The reason is that namespaces are an extension of the original
    /// XML specification (without namespaces) and it should be backward-compatible.
    ///
    /// When set to `false`, it won't check if a closing tag matches the corresponding
    /// opening tag. For example, `<mytag></different_tag>` will be permitted.
    ///
    /// If the XML is known to be sane (already processed, etc.) this saves extra time.
    ///
    /// Note that the emitted [`End`] event will not be modified if this is disabled,
    /// ie. it will contain the data of the mismatched end tag.
    ///
    /// Note, that setting this to `true` will lead to additional allocates that
    /// needed to store tag name for an [`End`] event. However if [`expand_empty_elements`]
    /// is also set, only one additional allocation will be performed that support
    /// both these options.
    ///
    /// Default: `true`
    ///
    /// [`Error::IllFormed(MismatchedEndTag)`]: crate::errors::IllFormedError::MismatchedEndTag
    /// [spec]: https://www.w3.org/TR/xml11/#dt-etag
    /// [`End`]: crate::events::Event::End
    /// [`expand_empty_elements`]: Self::expand_empty_elements
    pub check_end_names: bool,

    /// Whether empty elements should be split into an `Open` and a `Close` event.
    ///
    /// When set to `true`, all [`Empty`] events produced by a self-closing tag
    /// like `<tag/>` are expanded into a [`Start`] event followed by an [`End`]
    /// event. When set to `false` (the default), those tags are represented by
    /// an [`Empty`] event instead.
    ///
    /// Note, that setting this to `true` will lead to additional allocates that
    /// needed to store tag name for an [`End`] event. However if [`check_end_names`]
    /// is also set, only one additional allocation will be performed that support
    /// both these options.
    ///
    /// Default: `false`
    ///
    /// [`Empty`]: crate::events::Event::Empty
    /// [`Start`]: crate::events::Event::Start
    /// [`End`]: crate::events::Event::End
    /// [`check_end_names`]: Self::check_end_names
    pub expand_empty_elements: bool,

    /// Whether trailing whitespace after the markup name are trimmed in closing
    /// tags `</a >`.
    ///
    /// If `true` the emitted [`End`] event is stripped of trailing whitespace
    /// after the markup name.
    ///
    /// Note that if set to `false` and [`check_end_names`] is `true` the comparison
    /// of markup names is going to fail erroneously if a closing tag contains
    /// trailing whitespace.
    ///
    /// Default: `true`
    ///
    /// [`End`]: crate::events::Event::End
    /// [`check_end_names`]: Self::check_end_names
    pub trim_markup_names_in_closing_tags: bool,

    /// Whether whitespace before character data should be removed.
    ///
    /// When set to `true`, leading whitespace is trimmed in [`Text`] events.
    /// If after that the event is empty it will not be pushed.
    ///
    /// Default: `false`
    ///
    /// <div style="background:rgba(80, 240, 100, 0.20);padding:0.75em;">
    ///
    /// WARNING: With this option every text events will be trimmed which is
    /// incorrect behavior when text events delimited by comments, processing
    /// instructions or CDATA sections. To correctly trim data manually apply
    /// [`BytesText::inplace_trim_start`] and [`BytesText::inplace_trim_end`]
    /// only to necessary events.
    /// </div>
    ///
    /// [`Text`]: crate::events::Event::Text
    /// [`BytesText::inplace_trim_start`]: crate::events::BytesText::inplace_trim_start
    /// [`BytesText::inplace_trim_end`]: crate::events::BytesText::inplace_trim_end
    pub trim_text_start: bool,

    /// Whether whitespace after character data should be removed.
    ///
    /// When set to `true`, trailing whitespace is trimmed in [`Text`] events.
    /// If after that the event is empty it will not be pushed.
    ///
    /// Default: `false`
    ///
    /// <div style="background:rgba(80, 240, 100, 0.20);padding:0.75em;">
    ///
    /// WARNING: With this option every text events will be trimmed which is
    /// incorrect behavior when text events delimited by comments, processing
    /// instructions or CDATA sections. To correctly trim data manually apply
    /// [`BytesText::inplace_trim_start`] and [`BytesText::inplace_trim_end`]
    /// only to necessary events.
    /// </div>
    ///
    /// [`Text`]: crate::events::Event::Text
    /// [`BytesText::inplace_trim_start`]: crate::events::BytesText::inplace_trim_start
    /// [`BytesText::inplace_trim_end`]: crate::events::BytesText::inplace_trim_end
    pub trim_text_end: bool,
}

impl Config {
    /// Set both [`trim_text_start`] and [`trim_text_end`] to the same value.
    ///
    /// <div style="background:rgba(80, 240, 100, 0.20);padding:0.75em;">
    ///
    /// WARNING: With this option every text events will be trimmed which is
    /// incorrect behavior when text events delimited by comments, processing
    /// instructions or CDATA sections. To correctly trim data manually apply
    /// [`BytesText::inplace_trim_start`] and [`BytesText::inplace_trim_end`]
    /// only to necessary events.
    /// </div>
    ///
    /// [`trim_text_start`]: Self::trim_text_start
    /// [`trim_text_end`]: Self::trim_text_end
    /// [`BytesText::inplace_trim_start`]: crate::events::BytesText::inplace_trim_start
    /// [`BytesText::inplace_trim_end`]: crate::events::BytesText::inplace_trim_end
    #[inline]
    pub fn trim_text(&mut self, trim: bool) {
        self.trim_text_start = trim;
        self.trim_text_end = trim;
    }

    /// Turn on or off all checks for well-formedness. Currently it is that settings:
    /// - [`check_comments`](Self::check_comments)
    /// - [`check_end_names`](Self::check_end_names)
    #[inline]
    pub fn enable_all_checks(&mut self, enable: bool) {
        self.check_comments = enable;
        self.check_end_names = enable;
    }
}

impl Default for Config {
    fn default() -> Self {
        Self {
            allow_unmatched_ends: false,
            check_comments: false,
            check_end_names: true,
            expand_empty_elements: false,
            trim_markup_names_in_closing_tags: true,
            trim_text_start: false,
            trim_text_end: false,
        }
    }
}

////////////////////////////////////////////////////////////////////////////////////////////////////

macro_rules! read_event_impl {
    (
        $self:ident, $buf:ident,
        $reader:expr,
        $read_until_close:ident
        $(, $await:ident)?
    ) => {{
        let event = loop {
            break match $self.state.state {
                ParseState::Init => { // Go to InsideMarkup state
                    // If encoding set explicitly, we not need to detect it. For example,
                    // explicit UTF-8 set automatically if Reader was created using `from_str`.
                    // But we still need to remove BOM for consistency with no encoding
                    // feature enabled path
                    #[cfg(feature = "encoding")]
                    if let Some(encoding) = $reader.detect_encoding() $(.$await)? ? {
                        if $self.state.encoding.can_be_refined() {
                            $self.state.encoding = crate::reader::EncodingRef::BomDetected(encoding);
                        }
                    }

                    // Removes UTF-8 BOM if it is present
                    #[cfg(not(feature = "encoding"))]
                    $reader.remove_utf8_bom() $(.$await)? ?;

                    $self.state.state = ParseState::InsideText;
                    continue;
                },
                ParseState::InsideText => { // Go to InsideMarkup or Done state
                    if $self.state.config.trim_text_start {
                        $reader.skip_whitespace(&mut $self.state.offset) $(.$await)? ?;
                    }

                    match $reader.read_text($buf, &mut $self.state.offset) $(.$await)? {
                        ReadTextResult::Markup(buf) => {
                            $self.state.state = ParseState::InsideMarkup;
                            // Pass `buf` to the next next iteration of parsing loop
                            $buf = buf;
                            continue;
                        }
                        ReadTextResult::UpToMarkup(bytes) => {
                            $self.state.state = ParseState::InsideMarkup;
                            // FIXME: Can produce an empty event if:
                            // - event contains only spaces
                            // - trim_text_start = false
                            // - trim_text_end = true
                            Ok(Event::Text($self.state.emit_text(bytes)))
                        }
                        ReadTextResult::UpToEof(bytes) => {
                            $self.state.state = ParseState::Done;
                            // Trim bytes from end if required
                            let event = $self.state.emit_text(bytes);
                            if event.is_empty() {
                                Ok(Event::Eof)
                            } else {
                                Ok(Event::Text(event))
                            }
                        }
                        ReadTextResult::Err(e) => Err(Error::Io(e.into())),
                    }
                },
                // Go to InsideText state in next two arms
                ParseState::InsideMarkup => $self.$read_until_close($buf) $(.$await)?,
                ParseState::InsideEmpty => Ok(Event::End($self.state.close_expanded_empty())),
                ParseState::Done => Ok(Event::Eof),
            };
        };
        match event {
            // #513: In case of ill-formed errors we already consume the wrong data
            // and change the state. We can continue parsing if we wish
            Err(Error::IllFormed(_)) => {}
            Err(_) | Ok(Event::Eof) => $self.state.state = ParseState::Done,
            _ => {}
        }
        event
    }};
}

/// Read bytes up to the `>` and skip it. This method is expected to be called
/// after seeing the `<` symbol and skipping it. Inspects the next (current)
/// symbol and returns an appropriate [`Event`]:
///
/// |Symbol |Event
/// |-------|-------------------------------------
/// |`!`    |[`Comment`], [`CData`] or [`DocType`]
/// |`/`    |[`End`]
/// |`?`    |[`PI`]
/// |_other_|[`Start`] or [`Empty`]
///
/// Moves parser to the `InsideText` state.
///
/// [`Comment`]: Event::Comment
/// [`CData`]: Event::CData
/// [`DocType`]: Event::DocType
/// [`End`]: Event::End
/// [`PI`]: Event::PI
/// [`Start`]: Event::Start
/// [`Empty`]: Event::Empty
macro_rules! read_until_close {
    (
        $self:ident, $buf:ident,
        $reader:expr
        $(, $await:ident)?
    ) => {{
        $self.state.state = ParseState::InsideText;

        let start = $self.state.offset;
        match $reader.peek_one() $(.$await)? {
            // `<!` - comment, CDATA or DOCTYPE declaration
            Ok(Some(b'!')) => match $reader
                .read_bang_element($buf, &mut $self.state.offset)
                $(.$await)?
            {
                Ok((bang_type, bytes)) => $self.state.emit_bang(bang_type, bytes),
                Err(e) => {
                    // We want to report error at `<`, but offset was increased,
                    // so return it back (-1 for `<`)
                    $self.state.last_error_offset = start - 1;
                    Err(e)
                }
            },
            // `</` - closing tag
            // #776: We parse using ElementParser which allows us to have attributes
            // in close tags. While such tags are not allowed by the specification,
            // we anyway allow to parse them because:
            // - we do not check constraints during parsing. This is performed by the
            //   optional validate step which user should call manually
            // - if we just look for `>` we will parse `</tag attr=">" >` as end tag
            //   `</tag attr=">` and text `" >` which probably no one existing parser
            //   does. This is malformed XML, however it is tolerated by some parsers
            //   (e.g. the one used by Adobe Flash) and such documents do exist in the wild.
            Ok(Some(b'/')) => match $reader
                .read_with(ElementParser::Outside, $buf, &mut $self.state.offset)
                $(.$await)?
            {
                Ok(bytes) => $self.state.emit_end(bytes),
                Err(e) => {
                    // We want to report error at `<`, but offset was increased,
                    // so return it back (-1 for `<`)
                    $self.state.last_error_offset = start - 1;
                    Err(e)
                }
            },
            // `<?` - processing instruction
            Ok(Some(b'?')) => match $reader
                .read_with(PiParser(false), $buf, &mut $self.state.offset)
                $(.$await)?
            {
                Ok(bytes) => $self.state.emit_question_mark(bytes),
                Err(e) => {
                    // We want to report error at `<`, but offset was increased,
                    // so return it back (-1 for `<`)
                    $self.state.last_error_offset = start - 1;
                    Err(e)
                }
            },
            // `<...` - opening or self-closed tag
            Ok(Some(_)) => match $reader
                .read_with(ElementParser::Outside, $buf, &mut $self.state.offset)
                $(.$await)?
            {
                Ok(bytes) => Ok($self.state.emit_start(bytes)),
                Err(e) => {
                    // We want to report error at `<`, but offset was increased,
                    // so return it back (-1 for `<`)
                    $self.state.last_error_offset = start - 1;
                    Err(e)
                }
            },
            // `<` - syntax error, tag not closed
            Ok(None) => {
                // We want to report error at `<`, but offset was increased,
                // so return it back (-1 for `<`)
                $self.state.last_error_offset = start - 1;
                Err(Error::Syntax(SyntaxError::UnclosedTag))
            }
            Err(e) => Err(Error::Io(e.into())),
        }
    }};
}

/// Generalization of `read_to_end` method for buffered and borrowed readers
macro_rules! read_to_end {
    (
        // $self: &mut Reader
        $self:expr, $end:expr, $buf:expr,
        $read_event:ident,
        // Code block that performs clearing of internal buffer after read of each event
        $clear:block
        $(, $await:ident)?
    ) => {{
        // Because we take position after the event before the End event,
        // it is important that this position indicates beginning of the End event.
        // If between last event and the End event would be only spaces, then we
        // take position before the spaces, but spaces would be skipped without
        // generating event if `trim_text_start` is set to `true`. To prevent that
        // we temporary disable start text trimming.
        //
        // We also cannot take position after getting End event, because if
        // `trim_markup_names_in_closing_tags` is set to `true` (which is the default),
        // we do not known the real size of the End event that it is occupies in
        // the source and cannot correct the position after the End event.
        // So, we in any case should tweak parser configuration.
        let config = $self.config_mut();
        let trim = config.trim_text_start;
        config.trim_text_start = false;

        let start = $self.buffer_position();
        let mut depth = 0;
        loop {
            $clear
            let end = $self.buffer_position();
            match $self.$read_event($buf) $(.$await)? {
                Err(e) => {
                    $self.config_mut().trim_text_start = trim;
                    return Err(e);
                }

                Ok(Event::Start(e)) if e.name() == $end => depth += 1,
                Ok(Event::End(e)) if e.name() == $end => {
                    if depth == 0 {
                        $self.config_mut().trim_text_start = trim;
                        break start..end;
                    }
                    depth -= 1;
                }
                Ok(Event::Eof) => {
                    $self.config_mut().trim_text_start = trim;
                    return Err(Error::missed_end($end, $self.decoder()));
                }
                _ => (),
            }
        }
    }};
}

#[cfg(feature = "async-tokio")]
mod async_tokio;
mod buffered_reader;
mod ns_reader;
mod slice_reader;
mod state;

pub use ns_reader::NsReader;

/// Range of input in bytes, that corresponds to some piece of XML
pub type Span = Range<u64>;

////////////////////////////////////////////////////////////////////////////////////////////////////

/// Possible reader states. The state transition diagram (`true` and `false` shows
/// value of [`Config::expand_empty_elements`] option):
///
/// ```mermaid
/// flowchart LR
///   subgraph _
///     direction LR
///
///     Init         -- "(no event)"\n                                       --> InsideMarkup
///     InsideMarkup -- Decl, DocType, PI\nComment, CData\nStart, Empty, End --> InsideText
///     InsideText   -- "#lt;false#gt;\n(no event)"\nText                    --> InsideMarkup
///   end
///   InsideText     -- "#lt;true#gt;"\nStart --> InsideEmpty
///   InsideEmpty    -- End                   --> InsideText
///   _ -. Eof .-> Done
/// ```
#[derive(Clone, Debug)]
enum ParseState {
    /// Initial state in which reader stay after creation. Transition from that
    /// state could produce a `Text`, `Decl`, `Comment` or `Start` event. The next
    /// state is always `InsideMarkup`. The reader will never return to this state. The
    /// event emitted during transition to `InsideMarkup` is a `StartEvent` if the
    /// first symbol not `<`, otherwise no event are emitted.
    Init,
    /// State after seeing the `<` symbol. Depending on the next symbol all other
    /// events could be generated.
    ///
    /// After generating one event the reader moves to the `InsideText` state.
    InsideMarkup,
    /// State in which reader searches the `<` symbol of a markup. All bytes before
    /// that symbol will be returned in the [`Event::Text`] event. After that
    /// the reader moves to the `InsideMarkup` state.
    InsideText,
    /// This state is used only if option [`expand_empty_elements`] is set to `true`.
    /// Reader enters to this state when it is in a `InsideText` state and emits an
    /// [`Event::Start`] event. The next event emitted will be an [`Event::End`],
    /// after which reader returned to the `InsideText` state.
    ///
    /// [`expand_empty_elements`]: Config::expand_empty_elements
    InsideEmpty,
    /// Reader enters this state when `Eof` event generated or an error occurred.
    /// This is the last state, the reader stay in it forever.
    Done,
}

/// A reference to an encoding together with information about how it was retrieved.
///
/// The state transition diagram:
///
/// ```mermaid
/// flowchart LR
///   Implicit    -- from_str       --> Explicit
///   Implicit    -- BOM            --> BomDetected
///   Implicit    -- "encoding=..." --> XmlDetected
///   BomDetected -- "encoding=..." --> XmlDetected
/// ```
#[cfg(feature = "encoding")]
#[derive(Clone, Copy, Debug)]
enum EncodingRef {
    /// Encoding was implicitly assumed to have a specified value. It can be refined
    /// using BOM or by the XML declaration event (`<?xml encoding=... ?>`)
    Implicit(&'static Encoding),
    /// Encoding was explicitly set to the desired value. It cannot be changed
    /// nor by BOM, nor by parsing XML declaration (`<?xml encoding=... ?>`)
    Explicit(&'static Encoding),
    /// Encoding was detected from a byte order mark (BOM) or by the first bytes
    /// of the content. It can be refined by the XML declaration event (`<?xml encoding=... ?>`)
    BomDetected(&'static Encoding),
    /// Encoding was detected using XML declaration event (`<?xml encoding=... ?>`).
    /// It can no longer change
    XmlDetected(&'static Encoding),
}
#[cfg(feature = "encoding")]
impl EncodingRef {
    #[inline]
    const fn encoding(&self) -> &'static Encoding {
        match self {
            Self::Implicit(e) => e,
            Self::Explicit(e) => e,
            Self::BomDetected(e) => e,
            Self::XmlDetected(e) => e,
        }
    }
    #[inline]
    const fn can_be_refined(&self) -> bool {
        match self {
            Self::Implicit(_) | Self::BomDetected(_) => true,
            Self::Explicit(_) | Self::XmlDetected(_) => false,
        }
    }
}

////////////////////////////////////////////////////////////////////////////////////////////////////

/// A direct stream to the underlying [`Reader`]s reader which updates
/// [`Reader::buffer_position()`] when read from it.
#[derive(Debug)]
#[must_use = "streams do nothing unless read or polled"]
pub struct BinaryStream<'r, R> {
    inner: &'r mut R,
    offset: &'r mut u64,
}

impl<'r, R> BinaryStream<'r, R> {
    /// Returns current position in bytes in the original source.
    #[inline]
    pub const fn offset(&self) -> u64 {
        *self.offset
    }

    /// Gets a reference to the underlying reader.
    #[inline]
    pub const fn get_ref(&self) -> &R {
        self.inner
    }

    /// Gets a mutable reference to the underlying reader.
    ///
    /// Avoid read from this reader because this will not update reader's position
    /// and will lead to incorrect positions of errors. Read from this stream instead.
    #[inline]
    pub fn get_mut(&mut self) -> &mut R {
        self.inner
    }
}

impl<'r, R> io::Read for BinaryStream<'r, R>
where
    R: io::Read,
{
    #[inline]
    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
        let amt = self.inner.read(buf)?;
        *self.offset += amt as u64;
        Ok(amt)
    }
}

impl<'r, R> io::BufRead for BinaryStream<'r, R>
where
    R: io::BufRead,
{
    #[inline]
    fn fill_buf(&mut self) -> io::Result<&[u8]> {
        self.inner.fill_buf()
    }

    #[inline]
    fn consume(&mut self, amt: usize) {
        self.inner.consume(amt);
        *self.offset += amt as u64;
    }
}

////////////////////////////////////////////////////////////////////////////////////////////////////

/// A low level encoding-agnostic XML event reader.
///
/// Consumes bytes and streams XML [`Event`]s.
///
/// This reader does not manage namespace declarations and not able to resolve
/// prefixes. If you want these features, use the [`NsReader`].
///
/// # Examples
///
/// ```
/// use quick_xml::events::Event;
/// use quick_xml::reader::Reader;
///
/// let xml = r#"<tag1 att1 = "test">
///                 <tag2><!--Test comment-->Test</tag2>
///                 <tag2>Test 2</tag2>
///              </tag1>"#;
/// let mut reader = Reader::from_str(xml);
/// reader.config_mut().trim_text(true);
///
/// let mut count = 0;
/// let mut txt = Vec::new();
/// let mut buf = Vec::new();
///
/// // The `Reader` does not implement `Iterator` because it outputs borrowed data (`Cow`s)
/// loop {
///     // NOTE: this is the generic case when we don't know about the input BufRead.
///     // when the input is a &str or a &[u8], we don't actually need to use another
///     // buffer, we could directly call `reader.read_event()`
///     match reader.read_event_into(&mut buf) {
///         Err(e) => panic!("Error at position {}: {:?}", reader.error_position(), e),
///         // exits the loop when reaching end of file
///         Ok(Event::Eof) => break,
///
///         Ok(Event::Start(e)) => {
///             match e.name().as_ref() {
///                 b"tag1" => println!("attributes values: {:?}",
///                                     e.attributes().map(|a| a.unwrap().value)
///                                     .collect::<Vec<_>>()),
///                 b"tag2" => count += 1,
///                 _ => (),
///             }
///         }
///         Ok(Event::Text(e)) => txt.push(e.unescape().unwrap().into_owned()),
///
///         // There are several other `Event`s we do not consider here
///         _ => (),
///     }
///     // if we don't keep a borrow elsewhere, we can clear the buffer to keep memory usage low
///     buf.clear();
/// }
/// ```
///
/// [`NsReader`]: crate::reader::NsReader
#[derive(Clone)]
pub struct Reader<R> {
    /// Source of data for parse
    reader: R,
    /// Configuration and current parse state
    state: ReaderState,
}

/// Builder methods
impl<R> Reader<R> {
    /// Creates a `Reader` that reads from a given reader.
    pub fn from_reader(reader: R) -> Self {
        Self {
            reader,
            state: ReaderState::default(),
        }
    }

    /// Returns reference to the parser configuration
    pub const fn config(&self) -> &Config {
        &self.state.config
    }

    /// Returns mutable reference to the parser configuration
    pub fn config_mut(&mut self) -> &mut Config {
        &mut self.state.config
    }
}

/// Getters
impl<R> Reader<R> {
    /// Consumes `Reader` returning the underlying reader
    ///
    /// Can be used to compute line and column of a parsing error position
    ///
    /// # Examples
    ///
    /// ```
    /// # use pretty_assertions::assert_eq;
    /// use std::{str, io::Cursor};
    /// use quick_xml::events::Event;
    /// use quick_xml::reader::Reader;
    ///
    /// let xml = r#"<tag1 att1 = "test">
    ///                 <tag2><!--Test comment-->Test</tag2>
    ///                 <tag3>Test 2</tag3>
    ///              </tag1>"#;
    /// let mut reader = Reader::from_reader(Cursor::new(xml.as_bytes()));
    /// let mut buf = Vec::new();
    ///
    /// fn into_line_and_column(reader: Reader<Cursor<&[u8]>>) -> (usize, usize) {
    ///     // We known that size cannot exceed usize::MAX because we created parser from single &[u8]
    ///     let end_pos = reader.buffer_position() as usize;
    ///     let mut cursor = reader.into_inner();
    ///     let s = String::from_utf8(cursor.into_inner()[0..end_pos].to_owned())
    ///         .expect("can't make a string");
    ///     let mut line = 1;
    ///     let mut column = 0;
    ///     for c in s.chars() {
    ///         if c == '\n' {
    ///             line += 1;
    ///             column = 0;
    ///         } else {
    ///             column += 1;
    ///         }
    ///     }
    ///     (line, column)
    /// }
    ///
    /// loop {
    ///     match reader.read_event_into(&mut buf) {
    ///         Ok(Event::Start(ref e)) => match e.name().as_ref() {
    ///             b"tag1" | b"tag2" => (),
    ///             tag => {
    ///                 assert_eq!(b"tag3", tag);
    ///                 assert_eq!((3, 22), into_line_and_column(reader));
    ///                 break;
    ///             }
    ///         },
    ///         Ok(Event::Eof) => unreachable!(),
    ///         _ => (),
    ///     }
    ///     buf.clear();
    /// }
    /// ```
    pub fn into_inner(self) -> R {
        self.reader
    }

    /// Gets a reference to the underlying reader.
    pub const fn get_ref(&self) -> &R {
        &self.reader
    }

    /// Gets a mutable reference to the underlying reader.
    ///
    /// Avoid read from this reader because this will not update reader's position
    /// and will lead to incorrect positions of errors. If you want to read, use
    /// [`stream()`] instead.
    ///
    /// [`stream()`]: Self::stream
    pub fn get_mut(&mut self) -> &mut R {
        &mut self.reader
    }

    /// Gets the current byte position in the input data.
    pub const fn buffer_position(&self) -> u64 {
        // when internal state is InsideMarkup, we have actually read until '<',
        // which we don't want to show
        if let ParseState::InsideMarkup = self.state.state {
            self.state.offset - 1
        } else {
            self.state.offset
        }
    }

    /// Gets the last error byte position in the input data. If there is no errors
    /// yet, returns `0`.
    ///
    /// Unlike `buffer_position` it will point to the place where it is rational
    /// to report error to the end user. For example, all [`SyntaxError`]s are
    /// reported when the parser sees EOF inside of some kind of markup. The
    /// `buffer_position()` will point to the last byte of input which is not
    /// very useful. `error_position()` will point to the start of corresponding
    /// markup element (i. e. to the `<` character).
    ///
    /// This position is always `<= buffer_position()`.
    pub const fn error_position(&self) -> u64 {
        self.state.last_error_offset
    }

    /// Get the decoder, used to decode bytes, read by this reader, to the strings.
    ///
    /// If [`encoding`] feature is enabled, the used encoding may change after
    /// parsing the XML declaration, otherwise encoding is fixed to UTF-8.
    ///
    /// If [`encoding`] feature is enabled and no encoding is specified in declaration,
    /// defaults to UTF-8.
    ///
    /// [`encoding`]: ../index.html#encoding
    #[inline]
    pub const fn decoder(&self) -> Decoder {
        self.state.decoder()
    }

    /// Get the direct access to the underlying reader, but tracks the amount of
    /// read data and update [`Reader::buffer_position()`] accordingly.
    ///
    /// Note, that this method gives you access to the internal reader and read
    /// data will not be returned in any subsequent events read by `read_event`
    /// family of methods.
    ///
    /// # Example
    ///
    /// This example demonstrates how to read stream raw bytes from an XML document.
    /// This could be used to implement streaming read of text, or to read raw binary
    /// bytes embedded in an XML document. (Documents with embedded raw bytes are not
    /// valid XML, but XML-derived file formats exist where such documents are valid).
    ///
    /// ```
    /// # use pretty_assertions::assert_eq;
    /// use std::io::{BufRead, Read};
    /// use quick_xml::events::{BytesEnd, BytesStart, Event};
    /// use quick_xml::reader::Reader;
    ///
    /// let mut reader = Reader::from_str("<tag>binary << data&></tag>");
    /// //                                 ^    ^               ^     ^
    /// //                                 0    5              21    27
    ///
    /// assert_eq!(
    ///     (reader.read_event().unwrap(), reader.buffer_position()),
    ///     // 5 - end of the `<tag>`
    ///     (Event::Start(BytesStart::new("tag")), 5)
    /// );
    ///
    /// // Reading directly from underlying reader will not update position
    /// // let mut inner = reader.get_mut();
    ///
    /// // Reading from the stream() advances position
    /// let mut inner = reader.stream();
    ///
    /// // Read binary data. We must know its size
    /// let mut binary = [0u8; 16];
    /// inner.read_exact(&mut binary).unwrap();
    /// assert_eq!(&binary, b"binary << data&>");
    /// // 21 - end of the `binary << data&>`
    /// assert_eq!(inner.offset(), 21);
    /// assert_eq!(reader.buffer_position(), 21);
    ///
    /// assert_eq!(
    ///     (reader.read_event().unwrap(), reader.buffer_position()),
    ///     // 27 - end of the `</tag>`
    ///     (Event::End(BytesEnd::new("tag")), 27)
    /// );
    ///
    /// assert_eq!(reader.read_event().unwrap(), Event::Eof);
    /// ```
    #[inline]
    pub fn stream(&mut self) -> BinaryStream<R> {
        BinaryStream {
            inner: &mut self.reader,
            offset: &mut self.state.offset,
        }
    }
}

/// Private sync reading methods
impl<R> Reader<R> {
    /// Read text into the given buffer, and return an event that borrows from
    /// either that buffer or from the input itself, based on the type of the
    /// reader.
    fn read_event_impl<'i, B>(&mut self, mut buf: B) -> Result<Event<'i>, Error>
    where
        R: XmlSource<'i, B>,
    {
        read_event_impl!(self, buf, self.reader, read_until_close)
    }

    /// Private function to read until `>` is found. This function expects that
    /// it was called just after encounter a `<` symbol.
    fn read_until_close<'i, B>(&mut self, buf: B) -> Result<Event<'i>, Error>
    where
        R: XmlSource<'i, B>,
    {
        read_until_close!(self, buf, self.reader)
    }
}

////////////////////////////////////////////////////////////////////////////////////////////////////

/// Result of an attempt to read XML textual data from the reader.
enum ReadTextResult<'r, B> {
    /// Start of markup (`<` character) was found in the first byte.
    /// Contains buffer that should be returned back to the next iteration cycle
    /// to satisfy borrow checker requirements.
    Markup(B),
    /// Contains text block up to start of markup (`<` character).
    UpToMarkup(&'r [u8]),
    /// Contains text block up to EOF, start of markup (`<` character) was not found.
    UpToEof(&'r [u8]),
    /// IO error occurred.
    Err(io::Error),
}

/// Represents an input for a reader that can return borrowed data.
///
/// There are two implementors of this trait: generic one that read data from
/// `Self`, copies some part of it into a provided buffer of type `B` and then
/// returns data that borrow from that buffer.
///
/// The other implementor is for `&[u8]` and instead of copying data returns
/// borrowed data from `Self` instead. This implementation allows zero-copy
/// deserialization.
///
/// # Parameters
/// - `'r`: lifetime of a buffer from which events will borrow
/// - `B`: a type of a buffer that can be used to store data read from `Self` and
///   from which events can borrow
trait XmlSource<'r, B> {
    /// Removes UTF-8 BOM if it is present
    #[cfg(not(feature = "encoding"))]
    fn remove_utf8_bom(&mut self) -> io::Result<()>;

    /// Determines encoding from the start of input and removes BOM if it is present
    #[cfg(feature = "encoding")]
    fn detect_encoding(&mut self) -> io::Result<Option<&'static Encoding>>;

    /// Read input until start of markup (the `<`) is found or end of input is reached.
    ///
    /// # Parameters
    /// - `buf`: Buffer that could be filled from an input (`Self`) and
    ///   from which [events] could borrow their data
    /// - `position`: Will be increased by amount of bytes consumed
    ///
    /// [events]: crate::events::Event
    fn read_text(&mut self, buf: B, position: &mut u64) -> ReadTextResult<'r, B>;

    /// Read input until processing instruction is finished.
    ///
    /// This method expect that start sequence of a parser already was read.
    ///
    /// Returns a slice of data read up to the end of the thing being parsed.
    /// The end of thing and the returned content is determined by the used parser.
    ///
    /// If input (`Self`) is exhausted and no bytes was read, or if the specified
    /// parser could not find the ending sequence of the thing, returns `SyntaxError`.
    ///
    /// # Parameters
    /// - `buf`: Buffer that could be filled from an input (`Self`) and
    ///   from which [events] could borrow their data
    /// - `position`: Will be increased by amount of bytes consumed
    ///
    /// A `P` type parameter is used to preserve state between calls to the underlying
    /// reader which provides bytes fed into the parser.
    ///
    /// [events]: crate::events::Event
    fn read_with<P>(&mut self, parser: P, buf: B, position: &mut u64) -> Result<&'r [u8], Error>
    where
        P: Parser;

    /// Read input until comment or CDATA is finished.
    ///
    /// This method expect that `<` already was read.
    ///
    /// Returns a slice of data read up to end of comment or CDATA (`>`),
    /// which does not include into result.
    ///
    /// If input (`Self`) is exhausted and nothing was read, returns `None`.
    ///
    /// # Parameters
    /// - `buf`: Buffer that could be filled from an input (`Self`) and
    ///   from which [events] could borrow their data
    /// - `position`: Will be increased by amount of bytes consumed
    ///
    /// [events]: crate::events::Event
    fn read_bang_element(
        &mut self,
        buf: B,
        position: &mut u64,
    ) -> Result<(BangType, &'r [u8]), Error>;

    /// Consume and discard all the whitespace until the next non-whitespace
    /// character or EOF.
    ///
    /// # Parameters
    /// - `position`: Will be increased by amount of bytes consumed
    fn skip_whitespace(&mut self, position: &mut u64) -> io::Result<()>;

    /// Return one character without consuming it, so that future `read_*` calls
    /// will still include it. On EOF, return `None`.
    fn peek_one(&mut self) -> io::Result<Option<u8>>;
}

/// Possible elements started with `<!`
#[derive(Debug, PartialEq)]
enum BangType {
    /// <![CDATA[...]]>
    CData,
    /// <!--...-->
    Comment,
    /// <!DOCTYPE...>. Contains balance of '<' (+1) and '>' (-1)
    DocType(i32),
}
impl BangType {
    #[inline(always)]
    const fn new(byte: Option<u8>) -> Result<Self, SyntaxError> {
        Ok(match byte {
            Some(b'[') => Self::CData,
            Some(b'-') => Self::Comment,
            Some(b'D') | Some(b'd') => Self::DocType(0),
            _ => return Err(SyntaxError::InvalidBangMarkup),
        })
    }

    /// If element is finished, returns its content up to `>` symbol and
    /// an index of this symbol, otherwise returns `None`
    ///
    /// # Parameters
    /// - `buf`: buffer with data consumed on previous iterations
    /// - `chunk`: data read on current iteration and not yet consumed from reader
    #[inline(always)]
    fn parse<'b>(&mut self, buf: &[u8], chunk: &'b [u8]) -> Option<(&'b [u8], usize)> {
        match self {
            Self::Comment => {
                for i in memchr::memchr_iter(b'>', chunk) {
                    // Need to read at least 6 symbols (`!---->`) for properly finished comment
                    // <!----> - XML comment
                    //  012345 - i
                    if buf.len() + i > 4 {
                        if chunk[..i].ends_with(b"--") {
                            // We cannot strip last `--` from the buffer because we need it in case of
                            // check_comments enabled option. XML standard requires that comment
                            // will not end with `--->` sequence because this is a special case of
                            // `--` in the comment (https://www.w3.org/TR/xml11/#sec-comments)
                            return Some((&chunk[..i], i + 1)); // +1 for `>`
                        }
                        // End sequence `-|->` was splitted at |
                        //        buf --/   \-- chunk
                        if i == 1 && buf.ends_with(b"-") && chunk[0] == b'-' {
                            return Some((&chunk[..i], i + 1)); // +1 for `>`
                        }
                        // End sequence `--|>` was splitted at |
                        //         buf --/   \-- chunk
                        if i == 0 && buf.ends_with(b"--") {
                            return Some((&[], i + 1)); // +1 for `>`
                        }
                    }
                }
            }
            Self::CData => {
                for i in memchr::memchr_iter(b'>', chunk) {
                    if chunk[..i].ends_with(b"]]") {
                        return Some((&chunk[..i], i + 1)); // +1 for `>`
                    }
                    // End sequence `]|]>` was splitted at |
                    //        buf --/   \-- chunk
                    if i == 1 && buf.ends_with(b"]") && chunk[0] == b']' {
                        return Some((&chunk[..i], i + 1)); // +1 for `>`
                    }
                    // End sequence `]]|>` was splitted at |
                    //         buf --/   \-- chunk
                    if i == 0 && buf.ends_with(b"]]") {
                        return Some((&[], i + 1)); // +1 for `>`
                    }
                }
            }
            Self::DocType(ref mut balance) => {
                for i in memchr::memchr2_iter(b'<', b'>', chunk) {
                    if chunk[i] == b'<' {
                        *balance += 1;
                    } else {
                        if *balance == 0 {
                            return Some((&chunk[..i], i + 1)); // +1 for `>`
                        }
                        *balance -= 1;
                    }
                }
            }
        }
        None
    }
    #[inline]
    const fn to_err(&self) -> SyntaxError {
        match self {
            Self::CData => SyntaxError::UnclosedCData,
            Self::Comment => SyntaxError::UnclosedComment,
            Self::DocType(_) => SyntaxError::UnclosedDoctype,
        }
    }
}

////////////////////////////////////////////////////////////////////////////////////////////////////

#[cfg(test)]
mod test {
    /// Checks the internal implementation of the various reader methods
    macro_rules! check {
        (
            #[$test:meta]
            $read_event:ident,
            $read_until_close:ident,
            // constructor of the XML source on which internal functions will be called
            $source:path,
            // constructor of the buffer to which read data will stored
            $buf:expr
            $(, $async:ident, $await:ident)?
        ) => {
            mod read_bang_element {
                use super::*;
                use crate::errors::{Error, SyntaxError};
                use crate::reader::BangType;
                use crate::utils::Bytes;

                /// Checks that reading CDATA content works correctly
                mod cdata {
                    use super::*;
                    use pretty_assertions::assert_eq;

                    /// Checks that if input begins like CDATA element, but CDATA start sequence
                    /// is not finished, parsing ends with an error
                    #[$test]
                    #[ignore = "start CDATA sequence fully checked outside of `read_bang_element`"]
                    $($async)? fn not_properly_start() {
                        let buf = $buf;
                        let mut position = 1;
                        let mut input = b"![]]>other content".as_ref();
                        //                ^= 1

                        match $source(&mut input).read_bang_element(buf, &mut position) $(.$await)? {
                            Err(Error::Syntax(cause)) => assert_eq!(cause, SyntaxError::UnclosedCData),
                            x => panic!(
                                "Expected `Err(Syntax(_))`, but got `{:?}`",
                                x
                            ),
                        }
                        assert_eq!(position, 1);
                    }

                    /// Checks that if CDATA startup sequence was matched, but an end sequence
                    /// is not found, parsing ends with an error
                    #[$test]
                    $($async)? fn not_closed() {
                        let buf = $buf;
                        let mut position = 1;
                        let mut input = b"![CDATA[other content".as_ref();
                        //                ^= 1                 ^= 22

                        match $source(&mut input).read_bang_element(buf, &mut position) $(.$await)? {
                            Err(Error::Syntax(cause)) => assert_eq!(cause, SyntaxError::UnclosedCData),
                            x => panic!(
                                "Expected `Err(Syntax(_))`, but got `{:?}`",
                                x
                            ),
                        }
                        assert_eq!(position, 22);
                    }

                    /// Checks that CDATA element without content inside parsed successfully
                    #[$test]
                    $($async)? fn empty() {
                        let buf = $buf;
                        let mut position = 1;
                        let mut input = b"![CDATA[]]>other content".as_ref();
                        //                ^= 1       ^= 12

                        let (ty, bytes) = $source(&mut input)
                            .read_bang_element(buf, &mut position)
                            $(.$await)?
                            .unwrap();
                        assert_eq!(
                            (ty, Bytes(bytes)),
                            (BangType::CData, Bytes(b"![CDATA[]]"))
                        );
                        assert_eq!(position, 12);
                    }

                    /// Checks that CDATA element with content parsed successfully.
                    /// Additionally checks that sequences inside CDATA that may look like
                    /// a CDATA end sequence do not interrupt CDATA parsing
                    #[$test]
                    $($async)? fn with_content() {
                        let buf = $buf;
                        let mut position = 1;
                        let mut input = b"![CDATA[cdata]] ]>content]]>other content]]>".as_ref();
                        //                ^= 1                        ^= 29

                        let (ty, bytes) = $source(&mut input)
                            .read_bang_element(buf, &mut position)
                            $(.$await)?
                            .unwrap();
                        assert_eq!(
                            (ty, Bytes(bytes)),
                            (BangType::CData, Bytes(b"![CDATA[cdata]] ]>content]]"))
                        );
                        assert_eq!(position, 29);
                    }
                }

                /// Checks that reading XML comments works correctly. According to the [specification],
                /// comment data can contain any sequence except `--`:
                ///
                /// ```peg
                /// comment = '<--' (!'--' char)* '-->';
                /// char = [#x1-#x2C]
                ///      / [#x2E-#xD7FF]
                ///      / [#xE000-#xFFFD]
                ///      / [#x10000-#x10FFFF]
                /// ```
                ///
                /// The presence of this limitation, however, is simply a poorly designed specification
                /// (maybe for purpose of building of LL(1) XML parser) and quick-xml does not check for
                /// presence of these sequences by default. This tests allow such content.
                ///
                /// [specification]: https://www.w3.org/TR/xml11/#dt-comment
                mod comment {
                    use super::*;
                    use pretty_assertions::assert_eq;

                    #[$test]
                    #[ignore = "start comment sequence fully checked outside of `read_bang_element`"]
                    $($async)? fn not_properly_start() {
                        let buf = $buf;
                        let mut position = 1;
                        let mut input = b"!- -->other content".as_ref();
                        //                ^= 1

                        match $source(&mut input).read_bang_element(buf, &mut position) $(.$await)? {
                            Err(Error::Syntax(cause)) => assert_eq!(cause, SyntaxError::UnclosedComment),
                            x => panic!(
                                "Expected `Err(Syntax(_))`, but got `{:?}`",
                                x
                            ),
                        }
                        assert_eq!(position, 1);
                    }

                    #[$test]
                    $($async)? fn not_properly_end() {
                        let buf = $buf;
                        let mut position = 1;
                        let mut input = b"!->other content".as_ref();
                        //                ^= 1            ^= 17

                        match $source(&mut input).read_bang_element(buf, &mut position) $(.$await)? {
                            Err(Error::Syntax(cause)) => assert_eq!(cause, SyntaxError::UnclosedComment),
                            x => panic!(
                                "Expected `Err(Syntax(_))`, but got `{:?}`",
                                x
                            ),
                        }
                        assert_eq!(position, 17);
                    }

                    #[$test]
                    $($async)? fn not_closed1() {
                        let buf = $buf;
                        let mut position = 1;
                        let mut input = b"!--other content".as_ref();
                        //                ^= 1            ^= 17

                        match $source(&mut input).read_bang_element(buf, &mut position) $(.$await)? {
                            Err(Error::Syntax(cause)) => assert_eq!(cause, SyntaxError::UnclosedComment),
                            x => panic!(
                                "Expected `Err(Syntax(_))`, but got `{:?}`",
                                x
                            ),
                        }
                        assert_eq!(position, 17);
                    }

                    #[$test]
                    $($async)? fn not_closed2() {
                        let buf = $buf;
                        let mut position = 1;
                        let mut input = b"!-->other content".as_ref();
                        //                ^= 1             ^= 18

                        match $source(&mut input).read_bang_element(buf, &mut position) $(.$await)? {
                            Err(Error::Syntax(cause)) => assert_eq!(cause, SyntaxError::UnclosedComment),
                            x => panic!(
                                "Expected `Err(Syntax(_))`, but got `{:?}`",
                                x
                            ),
                        }
                        assert_eq!(position, 18);
                    }

                    #[$test]
                    $($async)? fn not_closed3() {
                        let buf = $buf;
                        let mut position = 1;
                        let mut input = b"!--->other content".as_ref();
                        //                ^= 1              ^= 19

                        match $source(&mut input).read_bang_element(buf, &mut position) $(.$await)? {
                            Err(Error::Syntax(cause)) => assert_eq!(cause, SyntaxError::UnclosedComment),
                            x => panic!(
                                "Expected `Err(Syntax(_))`, but got `{:?}`",
                                x
                            ),
                        }
                        assert_eq!(position, 19);
                    }

                    #[$test]
                    $($async)? fn empty() {
                        let buf = $buf;
                        let mut position = 1;
                        let mut input = b"!---->other content".as_ref();
                        //                ^= 1  ^= 7

                        let (ty, bytes) = $source(&mut input)
                            .read_bang_element(buf, &mut position)
                            $(.$await)?
                            .unwrap();
                        assert_eq!(
                            (ty, Bytes(bytes)),
                            (BangType::Comment, Bytes(b"!----"))
                        );
                        assert_eq!(position, 7);
                    }

                    #[$test]
                    $($async)? fn with_content() {
                        let buf = $buf;
                        let mut position = 1;
                        let mut input = b"!--->comment<--->other content".as_ref();
                        //                ^= 1             ^= 18

                        let (ty, bytes) = $source(&mut input)
                            .read_bang_element(buf, &mut position)
                            $(.$await)?
                            .unwrap();
                        assert_eq!(
                            (ty, Bytes(bytes)),
                            (BangType::Comment, Bytes(b"!--->comment<---"))
                        );
                        assert_eq!(position, 18);
                    }
                }

                /// Checks that reading DOCTYPE definition works correctly
                mod doctype {
                    use super::*;

                    mod uppercase {
                        use super::*;
                        use pretty_assertions::assert_eq;

                        #[$test]
                        $($async)? fn not_properly_start() {
                            let buf = $buf;
                            let mut position = 1;
                            let mut input = b"!D other content".as_ref();
                            //                ^= 1            ^= 17

                            match $source(&mut input).read_bang_element(buf, &mut position) $(.$await)? {
                                Err(Error::Syntax(cause)) => assert_eq!(cause, SyntaxError::UnclosedDoctype),
                                x => panic!(
                                    "Expected `Err(Syntax(_))`, but got `{:?}`",
                                    x
                                ),
                            }
                            assert_eq!(position, 17);
                        }

                        #[$test]
                        $($async)? fn without_space() {
                            let buf = $buf;
                            let mut position = 1;
                            let mut input = b"!DOCTYPEother content".as_ref();
                            //                ^= 1                 ^= 22

                            match $source(&mut input).read_bang_element(buf, &mut position) $(.$await)? {
                                Err(Error::Syntax(cause)) => assert_eq!(cause, SyntaxError::UnclosedDoctype),
                                x => panic!(
                                    "Expected `Err(Syntax(_))`, but got `{:?}`",
                                    x
                                ),
                            }
                            assert_eq!(position, 22);
                        }

                        #[$test]
                        $($async)? fn empty() {
                            let buf = $buf;
                            let mut position = 1;
                            let mut input = b"!DOCTYPE>other content".as_ref();
                            //                ^= 1     ^= 10

                            let (ty, bytes) = $source(&mut input)
                                .read_bang_element(buf, &mut position)
                                $(.$await)?
                                .unwrap();
                            assert_eq!(
                                (ty, Bytes(bytes)),
                                (BangType::DocType(0), Bytes(b"!DOCTYPE"))
                            );
                            assert_eq!(position, 10);
                        }

                        #[$test]
                        $($async)? fn not_closed() {
                            let buf = $buf;
                            let mut position = 1;
                            let mut input = b"!DOCTYPE other content".as_ref();
                            //                ^= 1                  ^23

                            match $source(&mut input).read_bang_element(buf, &mut position) $(.$await)? {
                                Err(Error::Syntax(cause)) => assert_eq!(cause, SyntaxError::UnclosedDoctype),
                                x => panic!(
                                    "Expected `Err(Syntax(_))`, but got `{:?}`",
                                    x
                                ),
                            }
                            assert_eq!(position, 23);
                        }
                    }

                    mod lowercase {
                        use super::*;
                        use pretty_assertions::assert_eq;

                        #[$test]
                        $($async)? fn not_properly_start() {
                            let buf = $buf;
                            let mut position = 1;
                            let mut input = b"!d other content".as_ref();
                            //                ^= 1            ^= 17

                            match $source(&mut input).read_bang_element(buf, &mut position) $(.$await)? {
                                Err(Error::Syntax(cause)) => assert_eq!(cause, SyntaxError::UnclosedDoctype),
                                x => panic!(
                                    "Expected `Err(Syntax(_))`, but got `{:?}`",
                                    x
                                ),
                            }
                            assert_eq!(position, 17);
                        }

                        #[$test]
                        $($async)? fn without_space() {
                            let buf = $buf;
                            let mut position = 1;
                            let mut input = b"!doctypeother content".as_ref();
                            //                ^= 1                 ^= 22

                            match $source(&mut input).read_bang_element(buf, &mut position) $(.$await)? {
                                Err(Error::Syntax(cause)) => assert_eq!(cause, SyntaxError::UnclosedDoctype),
                                x => panic!(
                                    "Expected `Err(Syntax(_))`, but got `{:?}`",
                                    x
                                ),
                            }
                            assert_eq!(position, 22);
                        }

                        #[$test]
                        $($async)? fn empty() {
                            let buf = $buf;
                            let mut position = 1;
                            let mut input = b"!doctype>other content".as_ref();
                            //                ^= 1     ^= 10

                            let (ty, bytes) = $source(&mut input)
                                .read_bang_element(buf, &mut position)
                                $(.$await)?
                                .unwrap();
                            assert_eq!(
                                (ty, Bytes(bytes)),
                                (BangType::DocType(0), Bytes(b"!doctype"))
                            );
                            assert_eq!(position, 10);
                        }

                        #[$test]
                        $($async)? fn not_closed() {
                            let buf = $buf;
                            let mut position = 1;
                            let mut input = b"!doctype other content".as_ref();
                            //                ^= 1                  ^= 23

                            match $source(&mut input).read_bang_element(buf, &mut position) $(.$await)? {
                                Err(Error::Syntax(cause)) => assert_eq!(cause, SyntaxError::UnclosedDoctype),
                                x => panic!(
                                    "Expected `Err(Syntax(_))`, but got `{:?}`",
                                    x
                                ),
                            }
                            assert_eq!(position, 23);
                        }
                    }
                }
            }

            mod read_element {
                use super::*;
                use crate::errors::{Error, SyntaxError};
                use crate::parser::ElementParser;
                use crate::utils::Bytes;
                use pretty_assertions::assert_eq;

                /// Checks that nothing was read from empty buffer
                #[$test]
                $($async)? fn empty() {
                    let buf = $buf;
                    let mut position = 1;
                    let mut input = b"".as_ref();
                    //                ^= 1

                    match $source(&mut input).read_with(ElementParser::default(), buf, &mut position) $(.$await)? {
                        Err(Error::Syntax(cause)) => assert_eq!(cause, SyntaxError::UnclosedTag),
                        x => panic!(
                            "Expected `Err(Syntax(_))`, but got `{:?}`",
                            x
                        ),
                    }
                    assert_eq!(position, 1);
                }

                mod open {
                    use super::*;
                    use pretty_assertions::assert_eq;

                    #[$test]
                    $($async)? fn empty_tag() {
                        let buf = $buf;
                        let mut position = 1;
                        let mut input = b">".as_ref();
                        //                 ^= 2

                        assert_eq!(
                            Bytes($source(&mut input).read_with(ElementParser::default(), buf, &mut position) $(.$await)? .unwrap()),
                            Bytes(b"")
                        );
                        assert_eq!(position, 2);
                    }

                    #[$test]
                    $($async)? fn normal() {
                        let buf = $buf;
                        let mut position = 1;
                        let mut input = b"tag>".as_ref();
                        //                    ^= 5

                        assert_eq!(
                            Bytes($source(&mut input).read_with(ElementParser::default(), buf, &mut position) $(.$await)? .unwrap()),
                            Bytes(b"tag")
                        );
                        assert_eq!(position, 5);
                    }

                    #[$test]
                    $($async)? fn empty_ns_empty_tag() {
                        let buf = $buf;
                        let mut position = 1;
                        let mut input = b":>".as_ref();
                        //                  ^= 3

                        assert_eq!(
                            Bytes($source(&mut input).read_with(ElementParser::default(), buf, &mut position) $(.$await)? .unwrap()),
                            Bytes(b":")
                        );
                        assert_eq!(position, 3);
                    }

                    #[$test]
                    $($async)? fn empty_ns() {
                        let buf = $buf;
                        let mut position = 1;
                        let mut input = b":tag>".as_ref();
                        //                     ^= 6

                        assert_eq!(
                            Bytes($source(&mut input).read_with(ElementParser::default(), buf, &mut position) $(.$await)? .unwrap()),
                            Bytes(b":tag")
                        );
                        assert_eq!(position, 6);
                    }

                    #[$test]
                    $($async)? fn with_attributes() {
                        let buf = $buf;
                        let mut position = 1;
                        let mut input = br#"tag  attr-1=">"  attr2  =  '>'  3attr>"#.as_ref();
                        //                                                        ^= 39

                        assert_eq!(
                            Bytes($source(&mut input).read_with(ElementParser::default(), buf, &mut position) $(.$await)? .unwrap()),
                            Bytes(br#"tag  attr-1=">"  attr2  =  '>'  3attr"#)
                        );
                        assert_eq!(position, 39);
                    }
                }

                mod self_closed {
                    use super::*;
                    use pretty_assertions::assert_eq;

                    #[$test]
                    $($async)? fn empty_tag() {
                        let buf = $buf;
                        let mut position = 1;
                        let mut input = b"/>".as_ref();
                        //                  ^= 3

                        assert_eq!(
                            Bytes($source(&mut input).read_with(ElementParser::default(), buf, &mut position) $(.$await)? .unwrap()),
                            Bytes(b"/")
                        );
                        assert_eq!(position, 3);
                    }

                    #[$test]
                    $($async)? fn normal() {
                        let buf = $buf;
                        let mut position = 1;
                        let mut input = b"tag/>".as_ref();
                        //                     ^= 6

                        assert_eq!(
                            Bytes($source(&mut input).read_with(ElementParser::default(), buf, &mut position) $(.$await)? .unwrap()),
                            Bytes(b"tag/")
                        );
                        assert_eq!(position, 6);
                    }

                    #[$test]
                    $($async)? fn empty_ns_empty_tag() {
                        let buf = $buf;
                        let mut position = 1;
                        let mut input = b":/>".as_ref();
                        //                   ^= 4

                        assert_eq!(
                            Bytes($source(&mut input).read_with(ElementParser::default(), buf, &mut position) $(.$await)? .unwrap()),
                            Bytes(b":/")
                        );
                        assert_eq!(position, 4);
                    }

                    #[$test]
                    $($async)? fn empty_ns() {
                        let buf = $buf;
                        let mut position = 1;
                        let mut input = b":tag/>".as_ref();
                        //                      ^= 7

                        assert_eq!(
                            Bytes($source(&mut input).read_with(ElementParser::default(), buf, &mut position) $(.$await)? .unwrap()),
                            Bytes(b":tag/")
                        );
                        assert_eq!(position, 7);
                    }

                    #[$test]
                    $($async)? fn with_attributes() {
                        let buf = $buf;
                        let mut position = 1;
                        let mut input = br#"tag  attr-1="/>"  attr2  =  '/>'  3attr/>"#.as_ref();
                        //                                                           ^= 42

                        assert_eq!(
                            Bytes($source(&mut input).read_with(ElementParser::default(), buf, &mut position) $(.$await)? .unwrap()),
                            Bytes(br#"tag  attr-1="/>"  attr2  =  '/>'  3attr/"#)
                        );
                        assert_eq!(position, 42);
                    }
                }

                mod close {
                    use super::*;
                    use pretty_assertions::assert_eq;

                    #[$test]
                    $($async)? fn empty_tag() {
                        let buf = $buf;
                        let mut position = 1;
                        let mut input = b"/ >".as_ref();
                        //                   ^= 4

                        assert_eq!(
                            Bytes($source(&mut input).read_with(ElementParser::default(), buf, &mut position) $(.$await)? .unwrap()),
                            Bytes(b"/ ")
                        );
                        assert_eq!(position, 4);
                    }

                    #[$test]
                    $($async)? fn normal() {
                        let buf = $buf;
                        let mut position = 1;
                        let mut input = b"/tag>".as_ref();
                        //                     ^= 6

                        assert_eq!(
                            Bytes($source(&mut input).read_with(ElementParser::default(), buf, &mut position) $(.$await)? .unwrap()),
                            Bytes(b"/tag")
                        );
                        assert_eq!(position, 6);
                    }

                    #[$test]
                    $($async)? fn empty_ns_empty_tag() {
                        let buf = $buf;
                        let mut position = 1;
                        let mut input = b"/:>".as_ref();
                        //                   ^= 4

                        assert_eq!(
                            Bytes($source(&mut input).read_with(ElementParser::default(), buf, &mut position) $(.$await)? .unwrap()),
                            Bytes(b"/:")
                        );
                        assert_eq!(position, 4);
                    }

                    #[$test]
                    $($async)? fn empty_ns() {
                        let buf = $buf;
                        let mut position = 1;
                        let mut input = b"/:tag>".as_ref();
                        //                      ^= 7

                        assert_eq!(
                            Bytes($source(&mut input).read_with(ElementParser::default(), buf, &mut position) $(.$await)? .unwrap()),
                            Bytes(b"/:tag")
                        );
                        assert_eq!(position, 7);
                    }

                    #[$test]
                    $($async)? fn with_attributes() {
                        let buf = $buf;
                        let mut position = 1;
                        let mut input = br#"/tag  attr-1=">"  attr2  =  '>'  3attr>"#.as_ref();
                        //                                                         ^= 40

                        assert_eq!(
                            Bytes($source(&mut input).read_with(ElementParser::default(), buf, &mut position) $(.$await)? .unwrap()),
                            Bytes(br#"/tag  attr-1=">"  attr2  =  '>'  3attr"#)
                        );
                        assert_eq!(position, 40);
                    }
                }
            }

            /// Ensures, that no empty `Text` events are generated
            mod $read_event {
                use crate::events::{BytesCData, BytesDecl, BytesEnd, BytesPI, BytesStart, BytesText, Event};
                use crate::reader::Reader;
                use pretty_assertions::assert_eq;

                /// When `encoding` feature is enabled, encoding should be detected
                /// from BOM (UTF-8) and BOM should be stripped.
                ///
                /// When `encoding` feature is disabled, UTF-8 is assumed and BOM
                /// character should be stripped for consistency
                #[$test]
                $($async)? fn bom_from_reader() {
                    let mut reader = Reader::from_reader("\u{feff}\u{feff}".as_bytes());

                    assert_eq!(
                        reader.$read_event($buf) $(.$await)? .unwrap(),
                        Event::Text(BytesText::from_escaped("\u{feff}"))
                    );

                    assert_eq!(
                        reader.$read_event($buf) $(.$await)? .unwrap(),
                        Event::Eof
                    );
                }

                /// When parsing from &str, encoding is fixed (UTF-8), so
                /// - when `encoding` feature is disabled, the behavior the
                ///   same as in `bom_from_reader` text
                /// - when `encoding` feature is enabled, the behavior should
                ///   stay consistent, so the first BOM character is stripped
                #[$test]
                $($async)? fn bom_from_str() {
                    let mut reader = Reader::from_str("\u{feff}\u{feff}");

                    assert_eq!(
                        reader.$read_event($buf) $(.$await)? .unwrap(),
                        Event::Text(BytesText::from_escaped("\u{feff}"))
                    );

                    assert_eq!(
                        reader.$read_event($buf) $(.$await)? .unwrap(),
                        Event::Eof
                    );
                }

                #[$test]
                $($async)? fn declaration() {
                    let mut reader = Reader::from_str("<?xml ?>");

                    assert_eq!(
                        reader.$read_event($buf) $(.$await)? .unwrap(),
                        Event::Decl(BytesDecl::from_start(BytesStart::from_content("xml ", 3)))
                    );
                }

                #[$test]
                $($async)? fn doctype() {
                    let mut reader = Reader::from_str("<!DOCTYPE x>");

                    assert_eq!(
                        reader.$read_event($buf) $(.$await)? .unwrap(),
                        Event::DocType(BytesText::from_escaped("x"))
                    );
                }

                #[$test]
                $($async)? fn processing_instruction() {
                    let mut reader = Reader::from_str("<?xml-stylesheet '? >\" ?>");

                    assert_eq!(
                        reader.$read_event($buf) $(.$await)? .unwrap(),
                        Event::PI(BytesPI::new("xml-stylesheet '? >\" "))
                    );
                }

                /// Lone closing tags are not allowed, so testing it together with start tag
                #[$test]
                $($async)? fn start_and_end() {
                    let mut reader = Reader::from_str("<tag></tag>");

                    assert_eq!(
                        reader.$read_event($buf) $(.$await)? .unwrap(),
                        Event::Start(BytesStart::new("tag"))
                    );

                    assert_eq!(
                        reader.$read_event($buf) $(.$await)? .unwrap(),
                        Event::End(BytesEnd::new("tag"))
                    );
                }

                #[$test]
                $($async)? fn empty() {
                    let mut reader = Reader::from_str("<tag/>");

                    assert_eq!(
                        reader.$read_event($buf) $(.$await)? .unwrap(),
                        Event::Empty(BytesStart::new("tag"))
                    );
                }

                #[$test]
                $($async)? fn text() {
                    let mut reader = Reader::from_str("text");

                    assert_eq!(
                        reader.$read_event($buf) $(.$await)? .unwrap(),
                        Event::Text(BytesText::from_escaped("text"))
                    );
                }

                #[$test]
                $($async)? fn cdata() {
                    let mut reader = Reader::from_str("<![CDATA[]]>");

                    assert_eq!(
                        reader.$read_event($buf) $(.$await)? .unwrap(),
                        Event::CData(BytesCData::new(""))
                    );
                }

                #[$test]
                $($async)? fn comment() {
                    let mut reader = Reader::from_str("<!---->");

                    assert_eq!(
                        reader.$read_event($buf) $(.$await)? .unwrap(),
                        Event::Comment(BytesText::from_escaped(""))
                    );
                }

                #[$test]
                $($async)? fn eof() {
                    let mut reader = Reader::from_str("");

                    assert_eq!(
                        reader.$read_event($buf) $(.$await)? .unwrap(),
                        Event::Eof
                    );
                }
            }
        };
    }

    // Export macros for the child modules:
    // - buffered_reader
    // - slice_reader
    pub(super) use check;
}