summaryrefslogtreecommitdiff
path: root/vendor/gopkg.in/yaml.v2/decode.go
blob: 129bc2a97d317534ef8081e92084851491698bc2 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
package yaml

import (
	"encoding"
	"encoding/base64"
	"fmt"
	"io"
	"math"
	"reflect"
	"strconv"
	"time"
)

const (
	documentNode = 1 << iota
	mappingNode
	sequenceNode
	scalarNode
	aliasNode
)

type node struct {
	kind         int
	line, column int
	tag          string
	// For an alias node, alias holds the resolved alias.
	alias    *node
	value    string
	implicit bool
	children []*node
	anchors  map[string]*node
}

// ----------------------------------------------------------------------------
// Parser, produces a node tree out of a libyaml event stream.

type parser struct {
	parser   yaml_parser_t
	event    yaml_event_t
	doc      *node
	doneInit bool
}

func newParser(b []byte) *parser {
	p := parser{}
	if !yaml_parser_initialize(&p.parser) {
		panic("failed to initialize YAML emitter")
	}
	if len(b) == 0 {
		b = []byte{'\n'}
	}
	yaml_parser_set_input_string(&p.parser, b)
	return &p
}

func newParserFromReader(r io.Reader) *parser {
	p := parser{}
	if !yaml_parser_initialize(&p.parser) {
		panic("failed to initialize YAML emitter")
	}
	yaml_parser_set_input_reader(&p.parser, r)
	return &p
}

func (p *parser) init() {
	if p.doneInit {
		return
	}
	p.expect(yaml_STREAM_START_EVENT)
	p.doneInit = true
}

func (p *parser) destroy() {
	if p.event.typ != yaml_NO_EVENT {
		yaml_event_delete(&p.event)
	}
	yaml_parser_delete(&p.parser)
}

// expect consumes an event from the event stream and
// checks that it's of the expected type.
func (p *parser) expect(e yaml_event_type_t) {
	if p.event.typ == yaml_NO_EVENT {
		if !yaml_parser_parse(&p.parser, &p.event) {
			p.fail()
		}
	}
	if p.event.typ == yaml_STREAM_END_EVENT {
		failf("attempted to go past the end of stream; corrupted value?")
	}
	if p.event.typ != e {
		p.parser.problem = fmt.Sprintf("expected %s event but got %s", e, p.event.typ)
		p.fail()
	}
	yaml_event_delete(&p.event)
	p.event.typ = yaml_NO_EVENT
}

// peek peeks at the next event in the event stream,
// puts the results into p.event and returns the event type.
func (p *parser) peek() yaml_event_type_t {
	if p.event.typ != yaml_NO_EVENT {
		return p.event.typ
	}
	if !yaml_parser_parse(&p.parser, &p.event) {
		p.fail()
	}
	return p.event.typ
}

func (p *parser) fail() {
	var where string
	var line int
	if p.parser.problem_mark.line != 0 {
		line = p.parser.problem_mark.line
		// Scanner errors don't iterate line before returning error
		if p.parser.error == yaml_SCANNER_ERROR {
			line++
		}
	} else if p.parser.context_mark.line != 0 {
		line = p.parser.context_mark.line
	}
	if line != 0 {
		where = "line " + strconv.Itoa(line) + ": "
	}
	var msg string
	if len(p.parser.problem) > 0 {
		msg = p.parser.problem
	} else {
		msg = "unknown problem parsing YAML content"
	}
	failf("%s%s", where, msg)
}

func (p *parser) anchor(n *node, anchor []byte) {
	if anchor != nil {
		p.doc.anchors[string(anchor)] = n
	}
}

func (p *parser) parse() *node {
	p.init()
	switch p.peek() {
	case yaml_SCALAR_EVENT:
		return p.scalar()
	case yaml_ALIAS_EVENT:
		return p.alias()
	case yaml_MAPPING_START_EVENT:
		return p.mapping()
	case yaml_SEQUENCE_START_EVENT:
		return p.sequence()
	case yaml_DOCUMENT_START_EVENT:
		return p.document()
	case yaml_STREAM_END_EVENT:
		// Happens when attempting to decode an empty buffer.
		return nil
	default:
		panic("attempted to parse unknown event: " + p.event.typ.String())
	}
}

func (p *parser) node(kind int) *node {
	return &node{
		kind:   kind,
		line:   p.event.start_mark.line,
		column: p.event.start_mark.column,
	}
}

func (p *parser) document() *node {
	n := p.node(documentNode)
	n.anchors = make(map[string]*node)
	p.doc = n
	p.expect(yaml_DOCUMENT_START_EVENT)
	n.children = append(n.children, p.parse())
	p.expect(yaml_DOCUMENT_END_EVENT)
	return n
}

func (p *parser) alias() *node {
	n := p.node(aliasNode)
	n.value = string(p.event.anchor)
	n.alias = p.doc.anchors[n.value]
	if n.alias == nil {
		failf("unknown anchor '%s' referenced", n.value)
	}
	p.expect(yaml_ALIAS_EVENT)
	return n
}

func (p *parser) scalar() *node {
	n := p.node(scalarNode)
	n.value = string(p.event.value)
	n.tag = string(p.event.tag)
	n.implicit = p.event.implicit
	p.anchor(n, p.event.anchor)
	p.expect(yaml_SCALAR_EVENT)
	return n
}

func (p *parser) sequence() *node {
	n := p.node(sequenceNode)
	p.anchor(n, p.event.anchor)
	p.expect(yaml_SEQUENCE_START_EVENT)
	for p.peek() != yaml_SEQUENCE_END_EVENT {
		n.children = append(n.children, p.parse())
	}
	p.expect(yaml_SEQUENCE_END_EVENT)
	return n
}

func (p *parser) mapping() *node {
	n := p.node(mappingNode)
	p.anchor(n, p.event.anchor)
	p.expect(yaml_MAPPING_START_EVENT)
	for p.peek() != yaml_MAPPING_END_EVENT {
		n.children = append(n.children, p.parse(), p.parse())
	}
	p.expect(yaml_MAPPING_END_EVENT)
	return n
}

// ----------------------------------------------------------------------------
// Decoder, unmarshals a node into a provided value.

type decoder struct {
	doc     *node
	aliases map[*node]bool
	mapType reflect.Type
	terrors []string
	strict  bool

	decodeCount int
	aliasCount  int
	aliasDepth  int
}

var (
	mapItemType    = reflect.TypeOf(MapItem{})
	durationType   = reflect.TypeOf(time.Duration(0))
	defaultMapType = reflect.TypeOf(map[interface{}]interface{}{})
	ifaceType      = defaultMapType.Elem()
	timeType       = reflect.TypeOf(time.Time{})
	ptrTimeType    = reflect.TypeOf(&time.Time{})
)

func newDecoder(strict bool) *decoder {
	d := &decoder{mapType: defaultMapType, strict: strict}
	d.aliases = make(map[*node]bool)
	return d
}

func (d *decoder) terror(n *node, tag string, out reflect.Value) {
	if n.tag != "" {
		tag = n.tag
	}
	value := n.value
	if tag != yaml_SEQ_TAG && tag != yaml_MAP_TAG {
		if len(value) > 10 {
			value = " `" + value[:7] + "...`"
		} else {
			value = " `" + value + "`"
		}
	}
	d.terrors = append(d.terrors, fmt.Sprintf("line %d: cannot unmarshal %s%s into %s", n.line+1, shortTag(tag), value, out.Type()))
}

func (d *decoder) callUnmarshaler(n *node, u Unmarshaler) (good bool) {
	terrlen := len(d.terrors)
	err := u.UnmarshalYAML(func(v interface{}) (err error) {
		defer handleErr(&err)
		d.unmarshal(n, reflect.ValueOf(v))
		if len(d.terrors) > terrlen {
			issues := d.terrors[terrlen:]
			d.terrors = d.terrors[:terrlen]
			return &TypeError{issues}
		}
		return nil
	})
	if e, ok := err.(*TypeError); ok {
		d.terrors = append(d.terrors, e.Errors...)
		return false
	}
	if err != nil {
		fail(err)
	}
	return true
}

// d.prepare initializes and dereferences pointers and calls UnmarshalYAML
// if a value is found to implement it.
// It returns the initialized and dereferenced out value, whether
// unmarshalling was already done by UnmarshalYAML, and if so whether
// its types unmarshalled appropriately.
//
// If n holds a null value, prepare returns before doing anything.
func (d *decoder) prepare(n *node, out reflect.Value) (newout reflect.Value, unmarshaled, good bool) {
	if n.tag == yaml_NULL_TAG || n.kind == scalarNode && n.tag == "" && (n.value == "null" || n.value == "~" || n.value == "" && n.implicit) {
		return out, false, false
	}
	again := true
	for again {
		again = false
		if out.Kind() == reflect.Ptr {
			if out.IsNil() {
				out.Set(reflect.New(out.Type().Elem()))
			}
			out = out.Elem()
			again = true
		}
		if out.CanAddr() {
			if u, ok := out.Addr().Interface().(Unmarshaler); ok {
				good = d.callUnmarshaler(n, u)
				return out, true, good
			}
		}
	}
	return out, false, false
}

const (
	// 400,000 decode operations is ~500kb of dense object declarations, or
	// ~5kb of dense object declarations with 10000% alias expansion
	alias_ratio_range_low = 400000

	// 4,000,000 decode operations is ~5MB of dense object declarations, or
	// ~4.5MB of dense object declarations with 10% alias expansion
	alias_ratio_range_high = 4000000

	// alias_ratio_range is the range over which we scale allowed alias ratios
	alias_ratio_range = float64(alias_ratio_range_high - alias_ratio_range_low)
)

func allowedAliasRatio(decodeCount int) float64 {
	switch {
	case decodeCount <= alias_ratio_range_low:
		// allow 99% to come from alias expansion for small-to-medium documents
		return 0.99
	case decodeCount >= alias_ratio_range_high:
		// allow 10% to come from alias expansion for very large documents
		return 0.10
	default:
		// scale smoothly from 99% down to 10% over the range.
		// this maps to 396,000 - 400,000 allowed alias-driven decodes over the range.
		// 400,000 decode operations is ~100MB of allocations in worst-case scenarios (single-item maps).
		return 0.99 - 0.89*(float64(decodeCount-alias_ratio_range_low)/alias_ratio_range)
	}
}

func (d *decoder) unmarshal(n *node, out reflect.Value) (good bool) {
	d.decodeCount++
	if d.aliasDepth > 0 {
		d.aliasCount++
	}
	if d.aliasCount > 100 && d.decodeCount > 1000 && float64(d.aliasCount)/float64(d.decodeCount) > allowedAliasRatio(d.decodeCount) {
		failf("document contains excessive aliasing")
	}
	switch n.kind {
	case documentNode:
		return d.document(n, out)
	case aliasNode:
		return d.alias(n, out)
	}
	out, unmarshaled, good := d.prepare(n, out)
	if unmarshaled {
		return good
	}
	switch n.kind {
	case scalarNode:
		good = d.scalar(n, out)
	case mappingNode:
		good = d.mapping(n, out)
	case sequenceNode:
		good = d.sequence(n, out)
	default:
		panic("internal error: unknown node kind: " + strconv.Itoa(n.kind))
	}
	return good
}

func (d *decoder) document(n *node, out reflect.Value) (good bool) {
	if len(n.children) == 1 {
		d.doc = n
		d.unmarshal(n.children[0], out)
		return true
	}
	return false
}

func (d *decoder) alias(n *node, out reflect.Value) (good bool) {
	if d.aliases[n] {
		// TODO this could actually be allowed in some circumstances.
		failf("anchor '%s' value contains itself", n.value)
	}
	d.aliases[n] = true
	d.aliasDepth++
	good = d.unmarshal(n.alias, out)
	d.aliasDepth--
	delete(d.aliases, n)
	return good
}

var zeroValue reflect.Value

func resetMap(out reflect.Value) {
	for _, k := range out.MapKeys() {
		out.SetMapIndex(k, zeroValue)
	}
}

func (d *decoder) scalar(n *node, out reflect.Value) bool {
	var tag string
	var resolved interface{}
	if n.tag == "" && !n.implicit {
		tag = yaml_STR_TAG
		resolved = n.value
	} else {
		tag, resolved = resolve(n.tag, n.value)
		if tag == yaml_BINARY_TAG {
			data, err := base64.StdEncoding.DecodeString(resolved.(string))
			if err != nil {
				failf("!!binary value contains invalid base64 data")
			}
			resolved = string(data)
		}
	}
	if resolved == nil {
		if out.Kind() == reflect.Map && !out.CanAddr() {
			resetMap(out)
		} else {
			out.Set(reflect.Zero(out.Type()))
		}
		return true
	}
	if resolvedv := reflect.ValueOf(resolved); out.Type() == resolvedv.Type() {
		// We've resolved to exactly the type we want, so use that.
		out.Set(resolvedv)
		return true
	}
	// Perhaps we can use the value as a TextUnmarshaler to
	// set its value.
	if out.CanAddr() {
		u, ok := out.Addr().Interface().(encoding.TextUnmarshaler)
		if ok {
			var text []byte
			if tag == yaml_BINARY_TAG {
				text = []byte(resolved.(string))
			} else {
				// We let any value be unmarshaled into TextUnmarshaler.
				// That might be more lax than we'd like, but the
				// TextUnmarshaler itself should bowl out any dubious values.
				text = []byte(n.value)
			}
			err := u.UnmarshalText(text)
			if err != nil {
				fail(err)
			}
			return true
		}
	}
	switch out.Kind() {
	case reflect.String:
		if tag == yaml_BINARY_TAG {
			out.SetString(resolved.(string))
			return true
		}
		if resolved != nil {
			out.SetString(n.value)
			return true
		}
	case reflect.Interface:
		if resolved == nil {
			out.Set(reflect.Zero(out.Type()))
		} else if tag == yaml_TIMESTAMP_TAG {
			// It looks like a timestamp but for backward compatibility
			// reasons we set it as a string, so that code that unmarshals
			// timestamp-like values into interface{} will continue to
			// see a string and not a time.Time.
			// TODO(v3) Drop this.
			out.Set(reflect.ValueOf(n.value))
		} else {
			out.Set(reflect.ValueOf(resolved))
		}
		return true
	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
		switch resolved := resolved.(type) {
		case int:
			if !out.OverflowInt(int64(resolved)) {
				out.SetInt(int64(resolved))
				return true
			}
		case int64:
			if !out.OverflowInt(resolved) {
				out.SetInt(resolved)
				return true
			}
		case uint64:
			if resolved <= math.MaxInt64 && !out.OverflowInt(int64(resolved)) {
				out.SetInt(int64(resolved))
				return true
			}
		case float64:
			if resolved <= math.MaxInt64 && !out.OverflowInt(int64(resolved)) {
				out.SetInt(int64(resolved))
				return true
			}
		case string:
			if out.Type() == durationType {
				d, err := time.ParseDuration(resolved)
				if err == nil {
					out.SetInt(int64(d))
					return true
				}
			}
		}
	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
		switch resolved := resolved.(type) {
		case int:
			if resolved >= 0 && !out.OverflowUint(uint64(resolved)) {
				out.SetUint(uint64(resolved))
				return true
			}
		case int64:
			if resolved >= 0 && !out.OverflowUint(uint64(resolved)) {
				out.SetUint(uint64(resolved))
				return true
			}
		case uint64:
			if !out.OverflowUint(uint64(resolved)) {
				out.SetUint(uint64(resolved))
				return true
			}
		case float64:
			if resolved <= math.MaxUint64 && !out.OverflowUint(uint64(resolved)) {
				out.SetUint(uint64(resolved))
				return true
			}
		}
	case reflect.Bool:
		switch resolved := resolved.(type) {
		case bool:
			out.SetBool(resolved)
			return true
		}
	case reflect.Float32, reflect.Float64:
		switch resolved := resolved.(type) {
		case int:
			out.SetFloat(float64(resolved))
			return true
		case int64:
			out.SetFloat(float64(resolved))
			return true
		case uint64:
			out.SetFloat(float64(resolved))
			return true
		case float64:
			out.SetFloat(resolved)
			return true
		}
	case reflect.Struct:
		if resolvedv := reflect.ValueOf(resolved); out.Type() == resolvedv.Type() {
			out.Set(resolvedv)
			return true
		}
	case reflect.Ptr:
		if out.Type().Elem() == reflect.TypeOf(resolved) {
			// TODO DOes this make sense? When is out a Ptr except when decoding a nil value?
			elem := reflect.New(out.Type().Elem())
			elem.Elem().Set(reflect.ValueOf(resolved))
			out.Set(elem)
			return true
		}
	}
	d.terror(n, tag, out)
	return false
}

func settableValueOf(i interface{}) reflect.Value {
	v := reflect.ValueOf(i)
	sv := reflect.New(v.Type()).Elem()
	sv.Set(v)
	return sv
}

func (d *decoder) sequence(n *node, out reflect.Value) (good bool) {
	l := len(n.children)

	var iface reflect.Value
	switch out.Kind() {
	case reflect.Slice:
		out.Set(reflect.MakeSlice(out.Type(), l, l))
	case reflect.Array:
		if l != out.Len() {
			failf("invalid array: want %d elements but got %d", out.Len(), l)
		}
	case reflect.Interface:
		// No type hints. Will have to use a generic sequence.
		iface = out
		out = settableValueOf(make([]interface{}, l))
	default:
		d.terror(n, yaml_SEQ_TAG, out)
		return false
	}
	et := out.Type().Elem()

	j := 0
	for i := 0; i < l; i++ {
		e := reflect.New(et).Elem()
		if ok := d.unmarshal(n.children[i], e); ok {
			out.Index(j).Set(e)
			j++
		}
	}
	if out.Kind() != reflect.Array {
		out.Set(out.Slice(0, j))
	}
	if iface.IsValid() {
		iface.Set(out)
	}
	return true
}

func (d *decoder) mapping(n *node, out reflect.Value) (good bool) {
	switch out.Kind() {
	case reflect.Struct:
		return d.mappingStruct(n, out)
	case reflect.Slice:
		return d.mappingSlice(n, out)
	case reflect.Map:
		// okay
	case reflect.Interface:
		if d.mapType.Kind() == reflect.Map {
			iface := out
			out = reflect.MakeMap(d.mapType)
			iface.Set(out)
		} else {
			slicev := reflect.New(d.mapType).Elem()
			if !d.mappingSlice(n, slicev) {
				return false
			}
			out.Set(slicev)
			return true
		}
	default:
		d.terror(n, yaml_MAP_TAG, out)
		return false
	}
	outt := out.Type()
	kt := outt.Key()
	et := outt.Elem()

	mapType := d.mapType
	if outt.Key() == ifaceType && outt.Elem() == ifaceType {
		d.mapType = outt
	}

	if out.IsNil() {
		out.Set(reflect.MakeMap(outt))
	}
	l := len(n.children)
	for i := 0; i < l; i += 2 {
		if isMerge(n.children[i]) {
			d.merge(n.children[i+1], out)
			continue
		}
		k := reflect.New(kt).Elem()
		if d.unmarshal(n.children[i], k) {
			kkind := k.Kind()
			if kkind == reflect.Interface {
				kkind = k.Elem().Kind()
			}
			if kkind == reflect.Map || kkind == reflect.Slice {
				failf("invalid map key: %#v", k.Interface())
			}
			e := reflect.New(et).Elem()
			if d.unmarshal(n.children[i+1], e) {
				d.setMapIndex(n.children[i+1], out, k, e)
			}
		}
	}
	d.mapType = mapType
	return true
}

func (d *decoder) setMapIndex(n *node, out, k, v reflect.Value) {
	if d.strict && out.MapIndex(k) != zeroValue {
		d.terrors = append(d.terrors, fmt.Sprintf("line %d: key %#v already set in map", n.line+1, k.Interface()))
		return
	}
	out.SetMapIndex(k, v)
}

func (d *decoder) mappingSlice(n *node, out reflect.Value) (good bool) {
	outt := out.Type()
	if outt.Elem() != mapItemType {
		d.terror(n, yaml_MAP_TAG, out)
		return false
	}

	mapType := d.mapType
	d.mapType = outt

	var slice []MapItem
	var l = len(n.children)
	for i := 0; i < l; i += 2 {
		if isMerge(n.children[i]) {
			d.merge(n.children[i+1], out)
			continue
		}
		item := MapItem{}
		k := reflect.ValueOf(&item.Key).Elem()
		if d.unmarshal(n.children[i], k) {
			v := reflect.ValueOf(&item.Value).Elem()
			if d.unmarshal(n.children[i+1], v) {
				slice = append(slice, item)
			}
		}
	}
	out.Set(reflect.ValueOf(slice))
	d.mapType = mapType
	return true
}

func (d *decoder) mappingStruct(n *node, out reflect.Value) (good bool) {
	sinfo, err := getStructInfo(out.Type())
	if err != nil {
		panic(err)
	}
	name := settableValueOf("")
	l := len(n.children)

	var inlineMap reflect.Value
	var elemType reflect.Type
	if sinfo.InlineMap != -1 {
		inlineMap = out.Field(sinfo.InlineMap)
		inlineMap.Set(reflect.New(inlineMap.Type()).Elem())
		elemType = inlineMap.Type().Elem()
	}

	var doneFields []bool
	if d.strict {
		doneFields = make([]bool, len(sinfo.FieldsList))
	}
	for i := 0; i < l; i += 2 {
		ni := n.children[i]
		if isMerge(ni) {
			d.merge(n.children[i+1], out)
			continue
		}
		if !d.unmarshal(ni, name) {
			continue
		}
		if info, ok := sinfo.FieldsMap[name.String()]; ok {
			if d.strict {
				if doneFields[info.Id] {
					d.terrors = append(d.terrors, fmt.Sprintf("line %d: field %s already set in type %s", ni.line+1, name.String(), out.Type()))
					continue
				}
				doneFields[info.Id] = true
			}
			var field reflect.Value
			if info.Inline == nil {
				field = out.Field(info.Num)
			} else {
				field = out.FieldByIndex(info.Inline)
			}
			d.unmarshal(n.children[i+1], field)
		} else if sinfo.InlineMap != -1 {
			if inlineMap.IsNil() {
				inlineMap.Set(reflect.MakeMap(inlineMap.Type()))
			}
			value := reflect.New(elemType).Elem()
			d.unmarshal(n.children[i+1], value)
			d.setMapIndex(n.children[i+1], inlineMap, name, value)
		} else if d.strict {
			d.terrors = append(d.terrors, fmt.Sprintf("line %d: field %s not found in type %s", ni.line+1, name.String(), out.Type()))
		}
	}
	return true
}

func failWantMap() {
	failf("map merge requires map or sequence of maps as the value")
}

func (d *decoder) merge(n *node, out reflect.Value) {
	switch n.kind {
	case mappingNode:
		d.unmarshal(n, out)
	case aliasNode:
		if n.alias != nil && n.alias.kind != mappingNode {
			failWantMap()
		}
		d.unmarshal(n, out)
	case sequenceNode:
		// Step backwards as earlier nodes take precedence.
		for i := len(n.children) - 1; i >= 0; i-- {
			ni := n.children[i]
			if ni.kind == aliasNode {
				if ni.alias != nil && ni.alias.kind != mappingNode {
					failWantMap()
				}
			} else if ni.kind != mappingNode {
				failWantMap()
			}
			d.unmarshal(ni, out)
		}
	default:
		failWantMap()
	}
}

func isMerge(n *node) bool {
	return n.kind == scalarNode && n.value == "<<" && (n.implicit == true || n.tag == yaml_MERGE_TAG)
}