File: format.go

package info (click to toggle)
golang-1.11 1.11.12-2
  • links: PTS, VCS
  • area: main
  • in suites: bullseye, experimental, sid
  • size: 107,360 kB
  • sloc: asm: 88,993; ansic: 8,174; perl: 2,007; sh: 1,804; xml: 623; python: 346; makefile: 123; cpp: 22; f90: 8; awk: 7
file content (1374 lines) | stat: -rw-r--r-- 39,799 bytes parent folder | download | duplicates (8)
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
// Copyright 2010 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package time

import "errors"

// These are predefined layouts for use in Time.Format and time.Parse.
// The reference time used in the layouts is the specific time:
//	Mon Jan 2 15:04:05 MST 2006
// which is Unix time 1136239445. Since MST is GMT-0700,
// the reference time can be thought of as
//	01/02 03:04:05PM '06 -0700
// To define your own format, write down what the reference time would look
// like formatted your way; see the values of constants like ANSIC,
// StampMicro or Kitchen for examples. The model is to demonstrate what the
// reference time looks like so that the Format and Parse methods can apply
// the same transformation to a general time value.
//
// Some valid layouts are invalid time values for time.Parse, due to formats
// such as _ for space padding and Z for zone information.
//
// Within the format string, an underscore _ represents a space that may be
// replaced by a digit if the following number (a day) has two digits; for
// compatibility with fixed-width Unix time formats.
//
// A decimal point followed by one or more zeros represents a fractional
// second, printed to the given number of decimal places. A decimal point
// followed by one or more nines represents a fractional second, printed to
// the given number of decimal places, with trailing zeros removed.
// When parsing (only), the input may contain a fractional second
// field immediately after the seconds field, even if the layout does not
// signify its presence. In that case a decimal point followed by a maximal
// series of digits is parsed as a fractional second.
//
// Numeric time zone offsets format as follows:
//	-0700  ±hhmm
//	-07:00 ±hh:mm
//	-07    ±hh
// Replacing the sign in the format with a Z triggers
// the ISO 8601 behavior of printing Z instead of an
// offset for the UTC zone. Thus:
//	Z0700  Z or ±hhmm
//	Z07:00 Z or ±hh:mm
//	Z07    Z or ±hh
//
// The recognized day of week formats are "Mon" and "Monday".
// The recognized month formats are "Jan" and "January".
//
// Text in the format string that is not recognized as part of the reference
// time is echoed verbatim during Format and expected to appear verbatim
// in the input to Parse.
//
// The executable example for Time.Format demonstrates the working
// of the layout string in detail and is a good reference.
//
// Note that the RFC822, RFC850, and RFC1123 formats should be applied
// only to local times. Applying them to UTC times will use "UTC" as the
// time zone abbreviation, while strictly speaking those RFCs require the
// use of "GMT" in that case.
// In general RFC1123Z should be used instead of RFC1123 for servers
// that insist on that format, and RFC3339 should be preferred for new protocols.
// RFC3339, RFC822, RFC822Z, RFC1123, and RFC1123Z are useful for formatting;
// when used with time.Parse they do not accept all the time formats
// permitted by the RFCs.
// The RFC3339Nano format removes trailing zeros from the seconds field
// and thus may not sort correctly once formatted.
const (
	ANSIC       = "Mon Jan _2 15:04:05 2006"
	UnixDate    = "Mon Jan _2 15:04:05 MST 2006"
	RubyDate    = "Mon Jan 02 15:04:05 -0700 2006"
	RFC822      = "02 Jan 06 15:04 MST"
	RFC822Z     = "02 Jan 06 15:04 -0700" // RFC822 with numeric zone
	RFC850      = "Monday, 02-Jan-06 15:04:05 MST"
	RFC1123     = "Mon, 02 Jan 2006 15:04:05 MST"
	RFC1123Z    = "Mon, 02 Jan 2006 15:04:05 -0700" // RFC1123 with numeric zone
	RFC3339     = "2006-01-02T15:04:05Z07:00"
	RFC3339Nano = "2006-01-02T15:04:05.999999999Z07:00"
	Kitchen     = "3:04PM"
	// Handy time stamps.
	Stamp      = "Jan _2 15:04:05"
	StampMilli = "Jan _2 15:04:05.000"
	StampMicro = "Jan _2 15:04:05.000000"
	StampNano  = "Jan _2 15:04:05.000000000"
)

const (
	_                        = iota
	stdLongMonth             = iota + stdNeedDate  // "January"
	stdMonth                                       // "Jan"
	stdNumMonth                                    // "1"
	stdZeroMonth                                   // "01"
	stdLongWeekDay                                 // "Monday"
	stdWeekDay                                     // "Mon"
	stdDay                                         // "2"
	stdUnderDay                                    // "_2"
	stdZeroDay                                     // "02"
	stdHour                  = iota + stdNeedClock // "15"
	stdHour12                                      // "3"
	stdZeroHour12                                  // "03"
	stdMinute                                      // "4"
	stdZeroMinute                                  // "04"
	stdSecond                                      // "5"
	stdZeroSecond                                  // "05"
	stdLongYear              = iota + stdNeedDate  // "2006"
	stdYear                                        // "06"
	stdPM                    = iota + stdNeedClock // "PM"
	stdpm                                          // "pm"
	stdTZ                    = iota                // "MST"
	stdISO8601TZ                                   // "Z0700"  // prints Z for UTC
	stdISO8601SecondsTZ                            // "Z070000"
	stdISO8601ShortTZ                              // "Z07"
	stdISO8601ColonTZ                              // "Z07:00" // prints Z for UTC
	stdISO8601ColonSecondsTZ                       // "Z07:00:00"
	stdNumTZ                                       // "-0700"  // always numeric
	stdNumSecondsTz                                // "-070000"
	stdNumShortTZ                                  // "-07"    // always numeric
	stdNumColonTZ                                  // "-07:00" // always numeric
	stdNumColonSecondsTZ                           // "-07:00:00"
	stdFracSecond0                                 // ".0", ".00", ... , trailing zeros included
	stdFracSecond9                                 // ".9", ".99", ..., trailing zeros omitted

	stdNeedDate  = 1 << 8             // need month, day, year
	stdNeedClock = 2 << 8             // need hour, minute, second
	stdArgShift  = 16                 // extra argument in high bits, above low stdArgShift
	stdMask      = 1<<stdArgShift - 1 // mask out argument
)

// std0x records the std values for "01", "02", ..., "06".
var std0x = [...]int{stdZeroMonth, stdZeroDay, stdZeroHour12, stdZeroMinute, stdZeroSecond, stdYear}

// startsWithLowerCase reports whether the string has a lower-case letter at the beginning.
// Its purpose is to prevent matching strings like "Month" when looking for "Mon".
func startsWithLowerCase(str string) bool {
	if len(str) == 0 {
		return false
	}
	c := str[0]
	return 'a' <= c && c <= 'z'
}

// nextStdChunk finds the first occurrence of a std string in
// layout and returns the text before, the std string, and the text after.
func nextStdChunk(layout string) (prefix string, std int, suffix string) {
	for i := 0; i < len(layout); i++ {
		switch c := int(layout[i]); c {
		case 'J': // January, Jan
			if len(layout) >= i+3 && layout[i:i+3] == "Jan" {
				if len(layout) >= i+7 && layout[i:i+7] == "January" {
					return layout[0:i], stdLongMonth, layout[i+7:]
				}
				if !startsWithLowerCase(layout[i+3:]) {
					return layout[0:i], stdMonth, layout[i+3:]
				}
			}

		case 'M': // Monday, Mon, MST
			if len(layout) >= i+3 {
				if layout[i:i+3] == "Mon" {
					if len(layout) >= i+6 && layout[i:i+6] == "Monday" {
						return layout[0:i], stdLongWeekDay, layout[i+6:]
					}
					if !startsWithLowerCase(layout[i+3:]) {
						return layout[0:i], stdWeekDay, layout[i+3:]
					}
				}
				if layout[i:i+3] == "MST" {
					return layout[0:i], stdTZ, layout[i+3:]
				}
			}

		case '0': // 01, 02, 03, 04, 05, 06
			if len(layout) >= i+2 && '1' <= layout[i+1] && layout[i+1] <= '6' {
				return layout[0:i], std0x[layout[i+1]-'1'], layout[i+2:]
			}

		case '1': // 15, 1
			if len(layout) >= i+2 && layout[i+1] == '5' {
				return layout[0:i], stdHour, layout[i+2:]
			}
			return layout[0:i], stdNumMonth, layout[i+1:]

		case '2': // 2006, 2
			if len(layout) >= i+4 && layout[i:i+4] == "2006" {
				return layout[0:i], stdLongYear, layout[i+4:]
			}
			return layout[0:i], stdDay, layout[i+1:]

		case '_': // _2, _2006
			if len(layout) >= i+2 && layout[i+1] == '2' {
				//_2006 is really a literal _, followed by stdLongYear
				if len(layout) >= i+5 && layout[i+1:i+5] == "2006" {
					return layout[0 : i+1], stdLongYear, layout[i+5:]
				}
				return layout[0:i], stdUnderDay, layout[i+2:]
			}

		case '3':
			return layout[0:i], stdHour12, layout[i+1:]

		case '4':
			return layout[0:i], stdMinute, layout[i+1:]

		case '5':
			return layout[0:i], stdSecond, layout[i+1:]

		case 'P': // PM
			if len(layout) >= i+2 && layout[i+1] == 'M' {
				return layout[0:i], stdPM, layout[i+2:]
			}

		case 'p': // pm
			if len(layout) >= i+2 && layout[i+1] == 'm' {
				return layout[0:i], stdpm, layout[i+2:]
			}

		case '-': // -070000, -07:00:00, -0700, -07:00, -07
			if len(layout) >= i+7 && layout[i:i+7] == "-070000" {
				return layout[0:i], stdNumSecondsTz, layout[i+7:]
			}
			if len(layout) >= i+9 && layout[i:i+9] == "-07:00:00" {
				return layout[0:i], stdNumColonSecondsTZ, layout[i+9:]
			}
			if len(layout) >= i+5 && layout[i:i+5] == "-0700" {
				return layout[0:i], stdNumTZ, layout[i+5:]
			}
			if len(layout) >= i+6 && layout[i:i+6] == "-07:00" {
				return layout[0:i], stdNumColonTZ, layout[i+6:]
			}
			if len(layout) >= i+3 && layout[i:i+3] == "-07" {
				return layout[0:i], stdNumShortTZ, layout[i+3:]
			}

		case 'Z': // Z070000, Z07:00:00, Z0700, Z07:00,
			if len(layout) >= i+7 && layout[i:i+7] == "Z070000" {
				return layout[0:i], stdISO8601SecondsTZ, layout[i+7:]
			}
			if len(layout) >= i+9 && layout[i:i+9] == "Z07:00:00" {
				return layout[0:i], stdISO8601ColonSecondsTZ, layout[i+9:]
			}
			if len(layout) >= i+5 && layout[i:i+5] == "Z0700" {
				return layout[0:i], stdISO8601TZ, layout[i+5:]
			}
			if len(layout) >= i+6 && layout[i:i+6] == "Z07:00" {
				return layout[0:i], stdISO8601ColonTZ, layout[i+6:]
			}
			if len(layout) >= i+3 && layout[i:i+3] == "Z07" {
				return layout[0:i], stdISO8601ShortTZ, layout[i+3:]
			}

		case '.': // .000 or .999 - repeated digits for fractional seconds.
			if i+1 < len(layout) && (layout[i+1] == '0' || layout[i+1] == '9') {
				ch := layout[i+1]
				j := i + 1
				for j < len(layout) && layout[j] == ch {
					j++
				}
				// String of digits must end here - only fractional second is all digits.
				if !isDigit(layout, j) {
					std := stdFracSecond0
					if layout[i+1] == '9' {
						std = stdFracSecond9
					}
					std |= (j - (i + 1)) << stdArgShift
					return layout[0:i], std, layout[j:]
				}
			}
		}
	}
	return layout, 0, ""
}

var longDayNames = []string{
	"Sunday",
	"Monday",
	"Tuesday",
	"Wednesday",
	"Thursday",
	"Friday",
	"Saturday",
}

var shortDayNames = []string{
	"Sun",
	"Mon",
	"Tue",
	"Wed",
	"Thu",
	"Fri",
	"Sat",
}

var shortMonthNames = []string{
	"Jan",
	"Feb",
	"Mar",
	"Apr",
	"May",
	"Jun",
	"Jul",
	"Aug",
	"Sep",
	"Oct",
	"Nov",
	"Dec",
}

var longMonthNames = []string{
	"January",
	"February",
	"March",
	"April",
	"May",
	"June",
	"July",
	"August",
	"September",
	"October",
	"November",
	"December",
}

// match reports whether s1 and s2 match ignoring case.
// It is assumed s1 and s2 are the same length.
func match(s1, s2 string) bool {
	for i := 0; i < len(s1); i++ {
		c1 := s1[i]
		c2 := s2[i]
		if c1 != c2 {
			// Switch to lower-case; 'a'-'A' is known to be a single bit.
			c1 |= 'a' - 'A'
			c2 |= 'a' - 'A'
			if c1 != c2 || c1 < 'a' || c1 > 'z' {
				return false
			}
		}
	}
	return true
}

func lookup(tab []string, val string) (int, string, error) {
	for i, v := range tab {
		if len(val) >= len(v) && match(val[0:len(v)], v) {
			return i, val[len(v):], nil
		}
	}
	return -1, val, errBad
}

// appendInt appends the decimal form of x to b and returns the result.
// If the decimal form (excluding sign) is shorter than width, the result is padded with leading 0's.
// Duplicates functionality in strconv, but avoids dependency.
func appendInt(b []byte, x int, width int) []byte {
	u := uint(x)
	if x < 0 {
		b = append(b, '-')
		u = uint(-x)
	}

	// Assemble decimal in reverse order.
	var buf [20]byte
	i := len(buf)
	for u >= 10 {
		i--
		q := u / 10
		buf[i] = byte('0' + u - q*10)
		u = q
	}
	i--
	buf[i] = byte('0' + u)

	// Add 0-padding.
	for w := len(buf) - i; w < width; w++ {
		b = append(b, '0')
	}

	return append(b, buf[i:]...)
}

// Never printed, just needs to be non-nil for return by atoi.
var atoiError = errors.New("time: invalid number")

// Duplicates functionality in strconv, but avoids dependency.
func atoi(s string) (x int, err error) {
	neg := false
	if s != "" && (s[0] == '-' || s[0] == '+') {
		neg = s[0] == '-'
		s = s[1:]
	}
	q, rem, err := leadingInt(s)
	x = int(q)
	if err != nil || rem != "" {
		return 0, atoiError
	}
	if neg {
		x = -x
	}
	return x, nil
}

// formatNano appends a fractional second, as nanoseconds, to b
// and returns the result.
func formatNano(b []byte, nanosec uint, n int, trim bool) []byte {
	u := nanosec
	var buf [9]byte
	for start := len(buf); start > 0; {
		start--
		buf[start] = byte(u%10 + '0')
		u /= 10
	}

	if n > 9 {
		n = 9
	}
	if trim {
		for n > 0 && buf[n-1] == '0' {
			n--
		}
		if n == 0 {
			return b
		}
	}
	b = append(b, '.')
	return append(b, buf[:n]...)
}

// String returns the time formatted using the format string
//	"2006-01-02 15:04:05.999999999 -0700 MST"
//
// If the time has a monotonic clock reading, the returned string
// includes a final field "m=±<value>", where value is the monotonic
// clock reading formatted as a decimal number of seconds.
//
// The returned string is meant for debugging; for a stable serialized
// representation, use t.MarshalText, t.MarshalBinary, or t.Format
// with an explicit format string.
func (t Time) String() string {
	s := t.Format("2006-01-02 15:04:05.999999999 -0700 MST")

	// Format monotonic clock reading as m=±ddd.nnnnnnnnn.
	if t.wall&hasMonotonic != 0 {
		m2 := uint64(t.ext)
		sign := byte('+')
		if t.ext < 0 {
			sign = '-'
			m2 = -m2
		}
		m1, m2 := m2/1e9, m2%1e9
		m0, m1 := m1/1e9, m1%1e9
		var buf []byte
		buf = append(buf, " m="...)
		buf = append(buf, sign)
		wid := 0
		if m0 != 0 {
			buf = appendInt(buf, int(m0), 0)
			wid = 9
		}
		buf = appendInt(buf, int(m1), wid)
		buf = append(buf, '.')
		buf = appendInt(buf, int(m2), 9)
		s += string(buf)
	}
	return s
}

// Format returns a textual representation of the time value formatted
// according to layout, which defines the format by showing how the reference
// time, defined to be
//	Mon Jan 2 15:04:05 -0700 MST 2006
// would be displayed if it were the value; it serves as an example of the
// desired output. The same display rules will then be applied to the time
// value.
//
// A fractional second is represented by adding a period and zeros
// to the end of the seconds section of layout string, as in "15:04:05.000"
// to format a time stamp with millisecond precision.
//
// Predefined layouts ANSIC, UnixDate, RFC3339 and others describe standard
// and convenient representations of the reference time. For more information
// about the formats and the definition of the reference time, see the
// documentation for ANSIC and the other constants defined by this package.
func (t Time) Format(layout string) string {
	const bufSize = 64
	var b []byte
	max := len(layout) + 10
	if max < bufSize {
		var buf [bufSize]byte
		b = buf[:0]
	} else {
		b = make([]byte, 0, max)
	}
	b = t.AppendFormat(b, layout)
	return string(b)
}

// AppendFormat is like Format but appends the textual
// representation to b and returns the extended buffer.
func (t Time) AppendFormat(b []byte, layout string) []byte {
	var (
		name, offset, abs = t.locabs()

		year  int = -1
		month Month
		day   int
		hour  int = -1
		min   int
		sec   int
	)
	// Each iteration generates one std value.
	for layout != "" {
		prefix, std, suffix := nextStdChunk(layout)
		if prefix != "" {
			b = append(b, prefix...)
		}
		if std == 0 {
			break
		}
		layout = suffix

		// Compute year, month, day if needed.
		if year < 0 && std&stdNeedDate != 0 {
			year, month, day, _ = absDate(abs, true)
		}

		// Compute hour, minute, second if needed.
		if hour < 0 && std&stdNeedClock != 0 {
			hour, min, sec = absClock(abs)
		}

		switch std & stdMask {
		case stdYear:
			y := year
			if y < 0 {
				y = -y
			}
			b = appendInt(b, y%100, 2)
		case stdLongYear:
			b = appendInt(b, year, 4)
		case stdMonth:
			b = append(b, month.String()[:3]...)
		case stdLongMonth:
			m := month.String()
			b = append(b, m...)
		case stdNumMonth:
			b = appendInt(b, int(month), 0)
		case stdZeroMonth:
			b = appendInt(b, int(month), 2)
		case stdWeekDay:
			b = append(b, absWeekday(abs).String()[:3]...)
		case stdLongWeekDay:
			s := absWeekday(abs).String()
			b = append(b, s...)
		case stdDay:
			b = appendInt(b, day, 0)
		case stdUnderDay:
			if day < 10 {
				b = append(b, ' ')
			}
			b = appendInt(b, day, 0)
		case stdZeroDay:
			b = appendInt(b, day, 2)
		case stdHour:
			b = appendInt(b, hour, 2)
		case stdHour12:
			// Noon is 12PM, midnight is 12AM.
			hr := hour % 12
			if hr == 0 {
				hr = 12
			}
			b = appendInt(b, hr, 0)
		case stdZeroHour12:
			// Noon is 12PM, midnight is 12AM.
			hr := hour % 12
			if hr == 0 {
				hr = 12
			}
			b = appendInt(b, hr, 2)
		case stdMinute:
			b = appendInt(b, min, 0)
		case stdZeroMinute:
			b = appendInt(b, min, 2)
		case stdSecond:
			b = appendInt(b, sec, 0)
		case stdZeroSecond:
			b = appendInt(b, sec, 2)
		case stdPM:
			if hour >= 12 {
				b = append(b, "PM"...)
			} else {
				b = append(b, "AM"...)
			}
		case stdpm:
			if hour >= 12 {
				b = append(b, "pm"...)
			} else {
				b = append(b, "am"...)
			}
		case stdISO8601TZ, stdISO8601ColonTZ, stdISO8601SecondsTZ, stdISO8601ShortTZ, stdISO8601ColonSecondsTZ, stdNumTZ, stdNumColonTZ, stdNumSecondsTz, stdNumShortTZ, stdNumColonSecondsTZ:
			// Ugly special case. We cheat and take the "Z" variants
			// to mean "the time zone as formatted for ISO 8601".
			if offset == 0 && (std == stdISO8601TZ || std == stdISO8601ColonTZ || std == stdISO8601SecondsTZ || std == stdISO8601ShortTZ || std == stdISO8601ColonSecondsTZ) {
				b = append(b, 'Z')
				break
			}
			zone := offset / 60 // convert to minutes
			absoffset := offset
			if zone < 0 {
				b = append(b, '-')
				zone = -zone
				absoffset = -absoffset
			} else {
				b = append(b, '+')
			}
			b = appendInt(b, zone/60, 2)
			if std == stdISO8601ColonTZ || std == stdNumColonTZ || std == stdISO8601ColonSecondsTZ || std == stdNumColonSecondsTZ {
				b = append(b, ':')
			}
			if std != stdNumShortTZ && std != stdISO8601ShortTZ {
				b = appendInt(b, zone%60, 2)
			}

			// append seconds if appropriate
			if std == stdISO8601SecondsTZ || std == stdNumSecondsTz || std == stdNumColonSecondsTZ || std == stdISO8601ColonSecondsTZ {
				if std == stdNumColonSecondsTZ || std == stdISO8601ColonSecondsTZ {
					b = append(b, ':')
				}
				b = appendInt(b, absoffset%60, 2)
			}

		case stdTZ:
			if name != "" {
				b = append(b, name...)
				break
			}
			// No time zone known for this time, but we must print one.
			// Use the -0700 format.
			zone := offset / 60 // convert to minutes
			if zone < 0 {
				b = append(b, '-')
				zone = -zone
			} else {
				b = append(b, '+')
			}
			b = appendInt(b, zone/60, 2)
			b = appendInt(b, zone%60, 2)
		case stdFracSecond0, stdFracSecond9:
			b = formatNano(b, uint(t.Nanosecond()), std>>stdArgShift, std&stdMask == stdFracSecond9)
		}
	}
	return b
}

var errBad = errors.New("bad value for field") // placeholder not passed to user

// ParseError describes a problem parsing a time string.
type ParseError struct {
	Layout     string
	Value      string
	LayoutElem string
	ValueElem  string
	Message    string
}

func quote(s string) string {
	return "\"" + s + "\""
}

// Error returns the string representation of a ParseError.
func (e *ParseError) Error() string {
	if e.Message == "" {
		return "parsing time " +
			quote(e.Value) + " as " +
			quote(e.Layout) + ": cannot parse " +
			quote(e.ValueElem) + " as " +
			quote(e.LayoutElem)
	}
	return "parsing time " +
		quote(e.Value) + e.Message
}

// isDigit reports whether s[i] is in range and is a decimal digit.
func isDigit(s string, i int) bool {
	if len(s) <= i {
		return false
	}
	c := s[i]
	return '0' <= c && c <= '9'
}

// getnum parses s[0:1] or s[0:2] (fixed forces the latter)
// as a decimal integer and returns the integer and the
// remainder of the string.
func getnum(s string, fixed bool) (int, string, error) {
	if !isDigit(s, 0) {
		return 0, s, errBad
	}
	if !isDigit(s, 1) {
		if fixed {
			return 0, s, errBad
		}
		return int(s[0] - '0'), s[1:], nil
	}
	return int(s[0]-'0')*10 + int(s[1]-'0'), s[2:], nil
}

func cutspace(s string) string {
	for len(s) > 0 && s[0] == ' ' {
		s = s[1:]
	}
	return s
}

// skip removes the given prefix from value,
// treating runs of space characters as equivalent.
func skip(value, prefix string) (string, error) {
	for len(prefix) > 0 {
		if prefix[0] == ' ' {
			if len(value) > 0 && value[0] != ' ' {
				return value, errBad
			}
			prefix = cutspace(prefix)
			value = cutspace(value)
			continue
		}
		if len(value) == 0 || value[0] != prefix[0] {
			return value, errBad
		}
		prefix = prefix[1:]
		value = value[1:]
	}
	return value, nil
}

// Parse parses a formatted string and returns the time value it represents.
// The layout defines the format by showing how the reference time,
// defined to be
//	Mon Jan 2 15:04:05 -0700 MST 2006
// would be interpreted if it were the value; it serves as an example of
// the input format. The same interpretation will then be made to the
// input string.
//
// Predefined layouts ANSIC, UnixDate, RFC3339 and others describe standard
// and convenient representations of the reference time. For more information
// about the formats and the definition of the reference time, see the
// documentation for ANSIC and the other constants defined by this package.
// Also, the executable example for Time.Format demonstrates the working
// of the layout string in detail and is a good reference.
//
// Elements omitted from the value are assumed to be zero or, when
// zero is impossible, one, so parsing "3:04pm" returns the time
// corresponding to Jan 1, year 0, 15:04:00 UTC (note that because the year is
// 0, this time is before the zero Time).
// Years must be in the range 0000..9999. The day of the week is checked
// for syntax but it is otherwise ignored.
//
// In the absence of a time zone indicator, Parse returns a time in UTC.
//
// When parsing a time with a zone offset like -0700, if the offset corresponds
// to a time zone used by the current location (Local), then Parse uses that
// location and zone in the returned time. Otherwise it records the time as
// being in a fabricated location with time fixed at the given zone offset.
//
// When parsing a time with a zone abbreviation like MST, if the zone abbreviation
// has a defined offset in the current location, then that offset is used.
// The zone abbreviation "UTC" is recognized as UTC regardless of location.
// If the zone abbreviation is unknown, Parse records the time as being
// in a fabricated location with the given zone abbreviation and a zero offset.
// This choice means that such a time can be parsed and reformatted with the
// same layout losslessly, but the exact instant used in the representation will
// differ by the actual zone offset. To avoid such problems, prefer time layouts
// that use a numeric zone offset, or use ParseInLocation.
func Parse(layout, value string) (Time, error) {
	return parse(layout, value, UTC, Local)
}

// ParseInLocation is like Parse but differs in two important ways.
// First, in the absence of time zone information, Parse interprets a time as UTC;
// ParseInLocation interprets the time as in the given location.
// Second, when given a zone offset or abbreviation, Parse tries to match it
// against the Local location; ParseInLocation uses the given location.
func ParseInLocation(layout, value string, loc *Location) (Time, error) {
	return parse(layout, value, loc, loc)
}

func parse(layout, value string, defaultLocation, local *Location) (Time, error) {
	alayout, avalue := layout, value
	rangeErrString := "" // set if a value is out of range
	amSet := false       // do we need to subtract 12 from the hour for midnight?
	pmSet := false       // do we need to add 12 to the hour?

	// Time being constructed.
	var (
		year       int
		month      int = 1 // January
		day        int = 1
		hour       int
		min        int
		sec        int
		nsec       int
		z          *Location
		zoneOffset int = -1
		zoneName   string
	)

	// Each iteration processes one std value.
	for {
		var err error
		prefix, std, suffix := nextStdChunk(layout)
		stdstr := layout[len(prefix) : len(layout)-len(suffix)]
		value, err = skip(value, prefix)
		if err != nil {
			return Time{}, &ParseError{alayout, avalue, prefix, value, ""}
		}
		if std == 0 {
			if len(value) != 0 {
				return Time{}, &ParseError{alayout, avalue, "", value, ": extra text: " + value}
			}
			break
		}
		layout = suffix
		var p string
		switch std & stdMask {
		case stdYear:
			if len(value) < 2 {
				err = errBad
				break
			}
			p, value = value[0:2], value[2:]
			year, err = atoi(p)
			if year >= 69 { // Unix time starts Dec 31 1969 in some time zones
				year += 1900
			} else {
				year += 2000
			}
		case stdLongYear:
			if len(value) < 4 || !isDigit(value, 0) {
				err = errBad
				break
			}
			p, value = value[0:4], value[4:]
			year, err = atoi(p)
		case stdMonth:
			month, value, err = lookup(shortMonthNames, value)
			month++
		case stdLongMonth:
			month, value, err = lookup(longMonthNames, value)
			month++
		case stdNumMonth, stdZeroMonth:
			month, value, err = getnum(value, std == stdZeroMonth)
			if month <= 0 || 12 < month {
				rangeErrString = "month"
			}
		case stdWeekDay:
			// Ignore weekday except for error checking.
			_, value, err = lookup(shortDayNames, value)
		case stdLongWeekDay:
			_, value, err = lookup(longDayNames, value)
		case stdDay, stdUnderDay, stdZeroDay:
			if std == stdUnderDay && len(value) > 0 && value[0] == ' ' {
				value = value[1:]
			}
			day, value, err = getnum(value, std == stdZeroDay)
			if day < 0 {
				// Note that we allow any one- or two-digit day here.
				rangeErrString = "day"
			}
		case stdHour:
			hour, value, err = getnum(value, false)
			if hour < 0 || 24 <= hour {
				rangeErrString = "hour"
			}
		case stdHour12, stdZeroHour12:
			hour, value, err = getnum(value, std == stdZeroHour12)
			if hour < 0 || 12 < hour {
				rangeErrString = "hour"
			}
		case stdMinute, stdZeroMinute:
			min, value, err = getnum(value, std == stdZeroMinute)
			if min < 0 || 60 <= min {
				rangeErrString = "minute"
			}
		case stdSecond, stdZeroSecond:
			sec, value, err = getnum(value, std == stdZeroSecond)
			if sec < 0 || 60 <= sec {
				rangeErrString = "second"
				break
			}
			// Special case: do we have a fractional second but no
			// fractional second in the format?
			if len(value) >= 2 && value[0] == '.' && isDigit(value, 1) {
				_, std, _ = nextStdChunk(layout)
				std &= stdMask
				if std == stdFracSecond0 || std == stdFracSecond9 {
					// Fractional second in the layout; proceed normally
					break
				}
				// No fractional second in the layout but we have one in the input.
				n := 2
				for ; n < len(value) && isDigit(value, n); n++ {
				}
				nsec, rangeErrString, err = parseNanoseconds(value, n)
				value = value[n:]
			}
		case stdPM:
			if len(value) < 2 {
				err = errBad
				break
			}
			p, value = value[0:2], value[2:]
			switch p {
			case "PM":
				pmSet = true
			case "AM":
				amSet = true
			default:
				err = errBad
			}
		case stdpm:
			if len(value) < 2 {
				err = errBad
				break
			}
			p, value = value[0:2], value[2:]
			switch p {
			case "pm":
				pmSet = true
			case "am":
				amSet = true
			default:
				err = errBad
			}
		case stdISO8601TZ, stdISO8601ColonTZ, stdISO8601SecondsTZ, stdISO8601ShortTZ, stdISO8601ColonSecondsTZ, stdNumTZ, stdNumShortTZ, stdNumColonTZ, stdNumSecondsTz, stdNumColonSecondsTZ:
			if (std == stdISO8601TZ || std == stdISO8601ShortTZ || std == stdISO8601ColonTZ) && len(value) >= 1 && value[0] == 'Z' {
				value = value[1:]
				z = UTC
				break
			}
			var sign, hour, min, seconds string
			if std == stdISO8601ColonTZ || std == stdNumColonTZ {
				if len(value) < 6 {
					err = errBad
					break
				}
				if value[3] != ':' {
					err = errBad
					break
				}
				sign, hour, min, seconds, value = value[0:1], value[1:3], value[4:6], "00", value[6:]
			} else if std == stdNumShortTZ || std == stdISO8601ShortTZ {
				if len(value) < 3 {
					err = errBad
					break
				}
				sign, hour, min, seconds, value = value[0:1], value[1:3], "00", "00", value[3:]
			} else if std == stdISO8601ColonSecondsTZ || std == stdNumColonSecondsTZ {
				if len(value) < 9 {
					err = errBad
					break
				}
				if value[3] != ':' || value[6] != ':' {
					err = errBad
					break
				}
				sign, hour, min, seconds, value = value[0:1], value[1:3], value[4:6], value[7:9], value[9:]
			} else if std == stdISO8601SecondsTZ || std == stdNumSecondsTz {
				if len(value) < 7 {
					err = errBad
					break
				}
				sign, hour, min, seconds, value = value[0:1], value[1:3], value[3:5], value[5:7], value[7:]
			} else {
				if len(value) < 5 {
					err = errBad
					break
				}
				sign, hour, min, seconds, value = value[0:1], value[1:3], value[3:5], "00", value[5:]
			}
			var hr, mm, ss int
			hr, err = atoi(hour)
			if err == nil {
				mm, err = atoi(min)
			}
			if err == nil {
				ss, err = atoi(seconds)
			}
			zoneOffset = (hr*60+mm)*60 + ss // offset is in seconds
			switch sign[0] {
			case '+':
			case '-':
				zoneOffset = -zoneOffset
			default:
				err = errBad
			}
		case stdTZ:
			// Does it look like a time zone?
			if len(value) >= 3 && value[0:3] == "UTC" {
				z = UTC
				value = value[3:]
				break
			}
			n, ok := parseTimeZone(value)
			if !ok {
				err = errBad
				break
			}
			zoneName, value = value[:n], value[n:]

		case stdFracSecond0:
			// stdFracSecond0 requires the exact number of digits as specified in
			// the layout.
			ndigit := 1 + (std >> stdArgShift)
			if len(value) < ndigit {
				err = errBad
				break
			}
			nsec, rangeErrString, err = parseNanoseconds(value, ndigit)
			value = value[ndigit:]

		case stdFracSecond9:
			if len(value) < 2 || value[0] != '.' || value[1] < '0' || '9' < value[1] {
				// Fractional second omitted.
				break
			}
			// Take any number of digits, even more than asked for,
			// because it is what the stdSecond case would do.
			i := 0
			for i < 9 && i+1 < len(value) && '0' <= value[i+1] && value[i+1] <= '9' {
				i++
			}
			nsec, rangeErrString, err = parseNanoseconds(value, 1+i)
			value = value[1+i:]
		}
		if rangeErrString != "" {
			return Time{}, &ParseError{alayout, avalue, stdstr, value, ": " + rangeErrString + " out of range"}
		}
		if err != nil {
			return Time{}, &ParseError{alayout, avalue, stdstr, value, ""}
		}
	}
	if pmSet && hour < 12 {
		hour += 12
	} else if amSet && hour == 12 {
		hour = 0
	}

	// Validate the day of the month.
	if day < 1 || day > daysIn(Month(month), year) {
		return Time{}, &ParseError{alayout, avalue, "", value, ": day out of range"}
	}

	if z != nil {
		return Date(year, Month(month), day, hour, min, sec, nsec, z), nil
	}

	if zoneOffset != -1 {
		t := Date(year, Month(month), day, hour, min, sec, nsec, UTC)
		t.addSec(-int64(zoneOffset))

		// Look for local zone with the given offset.
		// If that zone was in effect at the given time, use it.
		name, offset, _, _ := local.lookup(t.unixSec())
		if offset == zoneOffset && (zoneName == "" || name == zoneName) {
			t.setLoc(local)
			return t, nil
		}

		// Otherwise create fake zone to record offset.
		t.setLoc(FixedZone(zoneName, zoneOffset))
		return t, nil
	}

	if zoneName != "" {
		t := Date(year, Month(month), day, hour, min, sec, nsec, UTC)
		// Look for local zone with the given offset.
		// If that zone was in effect at the given time, use it.
		offset, ok := local.lookupName(zoneName, t.unixSec())
		if ok {
			t.addSec(-int64(offset))
			t.setLoc(local)
			return t, nil
		}

		// Otherwise, create fake zone with unknown offset.
		if len(zoneName) > 3 && zoneName[:3] == "GMT" {
			offset, _ = atoi(zoneName[3:]) // Guaranteed OK by parseGMT.
			offset *= 3600
		}
		t.setLoc(FixedZone(zoneName, offset))
		return t, nil
	}

	// Otherwise, fall back to default.
	return Date(year, Month(month), day, hour, min, sec, nsec, defaultLocation), nil
}

// parseTimeZone parses a time zone string and returns its length. Time zones
// are human-generated and unpredictable. We can't do precise error checking.
// On the other hand, for a correct parse there must be a time zone at the
// beginning of the string, so it's almost always true that there's one
// there. We look at the beginning of the string for a run of upper-case letters.
// If there are more than 5, it's an error.
// If there are 4 or 5 and the last is a T, it's a time zone.
// If there are 3, it's a time zone.
// Otherwise, other than special cases, it's not a time zone.
// GMT is special because it can have an hour offset.
func parseTimeZone(value string) (length int, ok bool) {
	if len(value) < 3 {
		return 0, false
	}
	// Special case 1: ChST and MeST are the only zones with a lower-case letter.
	if len(value) >= 4 && (value[:4] == "ChST" || value[:4] == "MeST") {
		return 4, true
	}
	// Special case 2: GMT may have an hour offset; treat it specially.
	if value[:3] == "GMT" {
		length = parseGMT(value)
		return length, true
	}
	// Special Case 3: Some time zones are not named, but have +/-00 format
	if value[0] == '+' || value[0] == '-' {
		length = parseSignedOffset(value)
		return length, true
	}
	// How many upper-case letters are there? Need at least three, at most five.
	var nUpper int
	for nUpper = 0; nUpper < 6; nUpper++ {
		if nUpper >= len(value) {
			break
		}
		if c := value[nUpper]; c < 'A' || 'Z' < c {
			break
		}
	}
	switch nUpper {
	case 0, 1, 2, 6:
		return 0, false
	case 5: // Must end in T to match.
		if value[4] == 'T' {
			return 5, true
		}
	case 4:
		// Must end in T, except one special case.
		if value[3] == 'T' || value[:4] == "WITA" {
			return 4, true
		}
	case 3:
		return 3, true
	}
	return 0, false
}

// parseGMT parses a GMT time zone. The input string is known to start "GMT".
// The function checks whether that is followed by a sign and a number in the
// range -14 through 12 excluding zero.
func parseGMT(value string) int {
	value = value[3:]
	if len(value) == 0 {
		return 3
	}

	return 3 + parseSignedOffset(value)
}

// parseSignedOffset parses a signed timezone offset (e.g. "+03" or "-04").
// The function checks for a signed number in the range -14 through +12 excluding zero.
// Returns length of the found offset string or 0 otherwise
func parseSignedOffset(value string) int {
	sign := value[0]
	if sign != '-' && sign != '+' {
		return 0
	}
	x, rem, err := leadingInt(value[1:])
	if err != nil {
		return 0
	}
	if sign == '-' {
		x = -x
	}
	if x == 0 || x < -14 || 12 < x {
		return 0
	}
	return len(value) - len(rem)
}

func parseNanoseconds(value string, nbytes int) (ns int, rangeErrString string, err error) {
	if value[0] != '.' {
		err = errBad
		return
	}
	if ns, err = atoi(value[1:nbytes]); err != nil {
		return
	}
	if ns < 0 || 1e9 <= ns {
		rangeErrString = "fractional second"
		return
	}
	// We need nanoseconds, which means scaling by the number
	// of missing digits in the format, maximum length 10. If it's
	// longer than 10, we won't scale.
	scaleDigits := 10 - nbytes
	for i := 0; i < scaleDigits; i++ {
		ns *= 10
	}
	return
}

var errLeadingInt = errors.New("time: bad [0-9]*") // never printed

// leadingInt consumes the leading [0-9]* from s.
func leadingInt(s string) (x int64, rem string, err error) {
	i := 0
	for ; i < len(s); i++ {
		c := s[i]
		if c < '0' || c > '9' {
			break
		}
		if x > (1<<63-1)/10 {
			// overflow
			return 0, "", errLeadingInt
		}
		x = x*10 + int64(c) - '0'
		if x < 0 {
			// overflow
			return 0, "", errLeadingInt
		}
	}
	return x, s[i:], nil
}

// leadingFraction consumes the leading [0-9]* from s.
// It is used only for fractions, so does not return an error on overflow,
// it just stops accumulating precision.
func leadingFraction(s string) (x int64, scale float64, rem string) {
	i := 0
	scale = 1
	overflow := false
	for ; i < len(s); i++ {
		c := s[i]
		if c < '0' || c > '9' {
			break
		}
		if overflow {
			continue
		}
		if x > (1<<63-1)/10 {
			// It's possible for overflow to give a positive number, so take care.
			overflow = true
			continue
		}
		y := x*10 + int64(c) - '0'
		if y < 0 {
			overflow = true
			continue
		}
		x = y
		scale *= 10
	}
	return x, scale, s[i:]
}

var unitMap = map[string]int64{
	"ns": int64(Nanosecond),
	"us": int64(Microsecond),
	"µs": int64(Microsecond), // U+00B5 = micro symbol
	"μs": int64(Microsecond), // U+03BC = Greek letter mu
	"ms": int64(Millisecond),
	"s":  int64(Second),
	"m":  int64(Minute),
	"h":  int64(Hour),
}

// ParseDuration parses a duration string.
// A duration string is a possibly signed sequence of
// decimal numbers, each with optional fraction and a unit suffix,
// such as "300ms", "-1.5h" or "2h45m".
// Valid time units are "ns", "us" (or "µs"), "ms", "s", "m", "h".
func ParseDuration(s string) (Duration, error) {
	// [-+]?([0-9]*(\.[0-9]*)?[a-z]+)+
	orig := s
	var d int64
	neg := false

	// Consume [-+]?
	if s != "" {
		c := s[0]
		if c == '-' || c == '+' {
			neg = c == '-'
			s = s[1:]
		}
	}
	// Special case: if all that is left is "0", this is zero.
	if s == "0" {
		return 0, nil
	}
	if s == "" {
		return 0, errors.New("time: invalid duration " + orig)
	}
	for s != "" {
		var (
			v, f  int64       // integers before, after decimal point
			scale float64 = 1 // value = v + f/scale
		)

		var err error

		// The next character must be [0-9.]
		if !(s[0] == '.' || '0' <= s[0] && s[0] <= '9') {
			return 0, errors.New("time: invalid duration " + orig)
		}
		// Consume [0-9]*
		pl := len(s)
		v, s, err = leadingInt(s)
		if err != nil {
			return 0, errors.New("time: invalid duration " + orig)
		}
		pre := pl != len(s) // whether we consumed anything before a period

		// Consume (\.[0-9]*)?
		post := false
		if s != "" && s[0] == '.' {
			s = s[1:]
			pl := len(s)
			f, scale, s = leadingFraction(s)
			post = pl != len(s)
		}
		if !pre && !post {
			// no digits (e.g. ".s" or "-.s")
			return 0, errors.New("time: invalid duration " + orig)
		}

		// Consume unit.
		i := 0
		for ; i < len(s); i++ {
			c := s[i]
			if c == '.' || '0' <= c && c <= '9' {
				break
			}
		}
		if i == 0 {
			return 0, errors.New("time: missing unit in duration " + orig)
		}
		u := s[:i]
		s = s[i:]
		unit, ok := unitMap[u]
		if !ok {
			return 0, errors.New("time: unknown unit " + u + " in duration " + orig)
		}
		if v > (1<<63-1)/unit {
			// overflow
			return 0, errors.New("time: invalid duration " + orig)
		}
		v *= unit
		if f > 0 {
			// float64 is needed to be nanosecond accurate for fractions of hours.
			// v >= 0 && (f*unit/scale) <= 3.6e+12 (ns/h, h is the largest unit)
			v += int64(float64(f) * (float64(unit) / scale))
			if v < 0 {
				// overflow
				return 0, errors.New("time: invalid duration " + orig)
			}
		}
		d += v
		if d < 0 {
			// overflow
			return 0, errors.New("time: invalid duration " + orig)
		}
	}

	if neg {
		d = -d
	}
	return Duration(d), nil
}