vendor/gopkg.in/yaml.v3/decode.go
changeset 256 6d9efbef00a9
child 260 445e01aede7e
equal deleted inserted replaced
255:4f153a23adab 256:6d9efbef00a9
       
     1 //
       
     2 // Copyright (c) 2011-2019 Canonical Ltd
       
     3 //
       
     4 // Licensed under the Apache License, Version 2.0 (the "License");
       
     5 // you may not use this file except in compliance with the License.
       
     6 // You may obtain a copy of the License at
       
     7 //
       
     8 //     http://www.apache.org/licenses/LICENSE-2.0
       
     9 //
       
    10 // Unless required by applicable law or agreed to in writing, software
       
    11 // distributed under the License is distributed on an "AS IS" BASIS,
       
    12 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
       
    13 // See the License for the specific language governing permissions and
       
    14 // limitations under the License.
       
    15 
       
    16 package yaml
       
    17 
       
    18 import (
       
    19 	"encoding"
       
    20 	"encoding/base64"
       
    21 	"fmt"
       
    22 	"io"
       
    23 	"math"
       
    24 	"reflect"
       
    25 	"strconv"
       
    26 	"time"
       
    27 )
       
    28 
       
    29 // ----------------------------------------------------------------------------
       
    30 // Parser, produces a node tree out of a libyaml event stream.
       
    31 
       
    32 type parser struct {
       
    33 	parser   yaml_parser_t
       
    34 	event    yaml_event_t
       
    35 	doc      *Node
       
    36 	anchors  map[string]*Node
       
    37 	doneInit bool
       
    38 	textless bool
       
    39 }
       
    40 
       
    41 func newParser(b []byte) *parser {
       
    42 	p := parser{}
       
    43 	if !yaml_parser_initialize(&p.parser) {
       
    44 		panic("failed to initialize YAML emitter")
       
    45 	}
       
    46 	if len(b) == 0 {
       
    47 		b = []byte{'\n'}
       
    48 	}
       
    49 	yaml_parser_set_input_string(&p.parser, b)
       
    50 	return &p
       
    51 }
       
    52 
       
    53 func newParserFromReader(r io.Reader) *parser {
       
    54 	p := parser{}
       
    55 	if !yaml_parser_initialize(&p.parser) {
       
    56 		panic("failed to initialize YAML emitter")
       
    57 	}
       
    58 	yaml_parser_set_input_reader(&p.parser, r)
       
    59 	return &p
       
    60 }
       
    61 
       
    62 func (p *parser) init() {
       
    63 	if p.doneInit {
       
    64 		return
       
    65 	}
       
    66 	p.anchors = make(map[string]*Node)
       
    67 	p.expect(yaml_STREAM_START_EVENT)
       
    68 	p.doneInit = true
       
    69 }
       
    70 
       
    71 func (p *parser) destroy() {
       
    72 	if p.event.typ != yaml_NO_EVENT {
       
    73 		yaml_event_delete(&p.event)
       
    74 	}
       
    75 	yaml_parser_delete(&p.parser)
       
    76 }
       
    77 
       
    78 // expect consumes an event from the event stream and
       
    79 // checks that it's of the expected type.
       
    80 func (p *parser) expect(e yaml_event_type_t) {
       
    81 	if p.event.typ == yaml_NO_EVENT {
       
    82 		if !yaml_parser_parse(&p.parser, &p.event) {
       
    83 			p.fail()
       
    84 		}
       
    85 	}
       
    86 	if p.event.typ == yaml_STREAM_END_EVENT {
       
    87 		failf("attempted to go past the end of stream; corrupted value?")
       
    88 	}
       
    89 	if p.event.typ != e {
       
    90 		p.parser.problem = fmt.Sprintf("expected %s event but got %s", e, p.event.typ)
       
    91 		p.fail()
       
    92 	}
       
    93 	yaml_event_delete(&p.event)
       
    94 	p.event.typ = yaml_NO_EVENT
       
    95 }
       
    96 
       
    97 // peek peeks at the next event in the event stream,
       
    98 // puts the results into p.event and returns the event type.
       
    99 func (p *parser) peek() yaml_event_type_t {
       
   100 	if p.event.typ != yaml_NO_EVENT {
       
   101 		return p.event.typ
       
   102 	}
       
   103 	if !yaml_parser_parse(&p.parser, &p.event) {
       
   104 		p.fail()
       
   105 	}
       
   106 	return p.event.typ
       
   107 }
       
   108 
       
   109 func (p *parser) fail() {
       
   110 	var where string
       
   111 	var line int
       
   112 	if p.parser.context_mark.line != 0 {
       
   113 		line = p.parser.context_mark.line
       
   114 		// Scanner errors don't iterate line before returning error
       
   115 		if p.parser.error == yaml_SCANNER_ERROR {
       
   116 			line++
       
   117 		}
       
   118 	} else if p.parser.problem_mark.line != 0 {
       
   119 		line = p.parser.problem_mark.line
       
   120 		// Scanner errors don't iterate line before returning error
       
   121 		if p.parser.error == yaml_SCANNER_ERROR {
       
   122 			line++
       
   123 		}
       
   124 	}
       
   125 	if line != 0 {
       
   126 		where = "line " + strconv.Itoa(line) + ": "
       
   127 	}
       
   128 	var msg string
       
   129 	if len(p.parser.problem) > 0 {
       
   130 		msg = p.parser.problem
       
   131 	} else {
       
   132 		msg = "unknown problem parsing YAML content"
       
   133 	}
       
   134 	failf("%s%s", where, msg)
       
   135 }
       
   136 
       
   137 func (p *parser) anchor(n *Node, anchor []byte) {
       
   138 	if anchor != nil {
       
   139 		n.Anchor = string(anchor)
       
   140 		p.anchors[n.Anchor] = n
       
   141 	}
       
   142 }
       
   143 
       
   144 func (p *parser) parse() *Node {
       
   145 	p.init()
       
   146 	switch p.peek() {
       
   147 	case yaml_SCALAR_EVENT:
       
   148 		return p.scalar()
       
   149 	case yaml_ALIAS_EVENT:
       
   150 		return p.alias()
       
   151 	case yaml_MAPPING_START_EVENT:
       
   152 		return p.mapping()
       
   153 	case yaml_SEQUENCE_START_EVENT:
       
   154 		return p.sequence()
       
   155 	case yaml_DOCUMENT_START_EVENT:
       
   156 		return p.document()
       
   157 	case yaml_STREAM_END_EVENT:
       
   158 		// Happens when attempting to decode an empty buffer.
       
   159 		return nil
       
   160 	case yaml_TAIL_COMMENT_EVENT:
       
   161 		panic("internal error: unexpected tail comment event (please report)")
       
   162 	default:
       
   163 		panic("internal error: attempted to parse unknown event (please report): " + p.event.typ.String())
       
   164 	}
       
   165 }
       
   166 
       
   167 func (p *parser) node(kind Kind, defaultTag, tag, value string) *Node {
       
   168 	var style Style
       
   169 	if tag != "" && tag != "!" {
       
   170 		tag = shortTag(tag)
       
   171 		style = TaggedStyle
       
   172 	} else if defaultTag != "" {
       
   173 		tag = defaultTag
       
   174 	} else if kind == ScalarNode {
       
   175 		tag, _ = resolve("", value)
       
   176 	}
       
   177 	n := &Node{
       
   178 		Kind:  kind,
       
   179 		Tag:   tag,
       
   180 		Value: value,
       
   181 		Style: style,
       
   182 	}
       
   183 	if !p.textless {
       
   184 		n.Line = p.event.start_mark.line + 1
       
   185 		n.Column = p.event.start_mark.column + 1
       
   186 		n.HeadComment = string(p.event.head_comment)
       
   187 		n.LineComment = string(p.event.line_comment)
       
   188 		n.FootComment = string(p.event.foot_comment)
       
   189 	}
       
   190 	return n
       
   191 }
       
   192 
       
   193 func (p *parser) parseChild(parent *Node) *Node {
       
   194 	child := p.parse()
       
   195 	parent.Content = append(parent.Content, child)
       
   196 	return child
       
   197 }
       
   198 
       
   199 func (p *parser) document() *Node {
       
   200 	n := p.node(DocumentNode, "", "", "")
       
   201 	p.doc = n
       
   202 	p.expect(yaml_DOCUMENT_START_EVENT)
       
   203 	p.parseChild(n)
       
   204 	if p.peek() == yaml_DOCUMENT_END_EVENT {
       
   205 		n.FootComment = string(p.event.foot_comment)
       
   206 	}
       
   207 	p.expect(yaml_DOCUMENT_END_EVENT)
       
   208 	return n
       
   209 }
       
   210 
       
   211 func (p *parser) alias() *Node {
       
   212 	n := p.node(AliasNode, "", "", string(p.event.anchor))
       
   213 	n.Alias = p.anchors[n.Value]
       
   214 	if n.Alias == nil {
       
   215 		failf("unknown anchor '%s' referenced", n.Value)
       
   216 	}
       
   217 	p.expect(yaml_ALIAS_EVENT)
       
   218 	return n
       
   219 }
       
   220 
       
   221 func (p *parser) scalar() *Node {
       
   222 	var parsedStyle = p.event.scalar_style()
       
   223 	var nodeStyle Style
       
   224 	switch {
       
   225 	case parsedStyle&yaml_DOUBLE_QUOTED_SCALAR_STYLE != 0:
       
   226 		nodeStyle = DoubleQuotedStyle
       
   227 	case parsedStyle&yaml_SINGLE_QUOTED_SCALAR_STYLE != 0:
       
   228 		nodeStyle = SingleQuotedStyle
       
   229 	case parsedStyle&yaml_LITERAL_SCALAR_STYLE != 0:
       
   230 		nodeStyle = LiteralStyle
       
   231 	case parsedStyle&yaml_FOLDED_SCALAR_STYLE != 0:
       
   232 		nodeStyle = FoldedStyle
       
   233 	}
       
   234 	var nodeValue = string(p.event.value)
       
   235 	var nodeTag = string(p.event.tag)
       
   236 	var defaultTag string
       
   237 	if nodeStyle == 0 {
       
   238 		if nodeValue == "<<" {
       
   239 			defaultTag = mergeTag
       
   240 		}
       
   241 	} else {
       
   242 		defaultTag = strTag
       
   243 	}
       
   244 	n := p.node(ScalarNode, defaultTag, nodeTag, nodeValue)
       
   245 	n.Style |= nodeStyle
       
   246 	p.anchor(n, p.event.anchor)
       
   247 	p.expect(yaml_SCALAR_EVENT)
       
   248 	return n
       
   249 }
       
   250 
       
   251 func (p *parser) sequence() *Node {
       
   252 	n := p.node(SequenceNode, seqTag, string(p.event.tag), "")
       
   253 	if p.event.sequence_style()&yaml_FLOW_SEQUENCE_STYLE != 0 {
       
   254 		n.Style |= FlowStyle
       
   255 	}
       
   256 	p.anchor(n, p.event.anchor)
       
   257 	p.expect(yaml_SEQUENCE_START_EVENT)
       
   258 	for p.peek() != yaml_SEQUENCE_END_EVENT {
       
   259 		p.parseChild(n)
       
   260 	}
       
   261 	n.LineComment = string(p.event.line_comment)
       
   262 	n.FootComment = string(p.event.foot_comment)
       
   263 	p.expect(yaml_SEQUENCE_END_EVENT)
       
   264 	return n
       
   265 }
       
   266 
       
   267 func (p *parser) mapping() *Node {
       
   268 	n := p.node(MappingNode, mapTag, string(p.event.tag), "")
       
   269 	block := true
       
   270 	if p.event.mapping_style()&yaml_FLOW_MAPPING_STYLE != 0 {
       
   271 		block = false
       
   272 		n.Style |= FlowStyle
       
   273 	}
       
   274 	p.anchor(n, p.event.anchor)
       
   275 	p.expect(yaml_MAPPING_START_EVENT)
       
   276 	for p.peek() != yaml_MAPPING_END_EVENT {
       
   277 		k := p.parseChild(n)
       
   278 		if block && k.FootComment != "" {
       
   279 			// Must be a foot comment for the prior value when being dedented.
       
   280 			if len(n.Content) > 2 {
       
   281 				n.Content[len(n.Content)-3].FootComment = k.FootComment
       
   282 				k.FootComment = ""
       
   283 			}
       
   284 		}
       
   285 		v := p.parseChild(n)
       
   286 		if k.FootComment == "" && v.FootComment != "" {
       
   287 			k.FootComment = v.FootComment
       
   288 			v.FootComment = ""
       
   289 		}
       
   290 		if p.peek() == yaml_TAIL_COMMENT_EVENT {
       
   291 			if k.FootComment == "" {
       
   292 				k.FootComment = string(p.event.foot_comment)
       
   293 			}
       
   294 			p.expect(yaml_TAIL_COMMENT_EVENT)
       
   295 		}
       
   296 	}
       
   297 	n.LineComment = string(p.event.line_comment)
       
   298 	n.FootComment = string(p.event.foot_comment)
       
   299 	if n.Style&FlowStyle == 0 && n.FootComment != "" && len(n.Content) > 1 {
       
   300 		n.Content[len(n.Content)-2].FootComment = n.FootComment
       
   301 		n.FootComment = ""
       
   302 	}
       
   303 	p.expect(yaml_MAPPING_END_EVENT)
       
   304 	return n
       
   305 }
       
   306 
       
   307 // ----------------------------------------------------------------------------
       
   308 // Decoder, unmarshals a node into a provided value.
       
   309 
       
   310 type decoder struct {
       
   311 	doc     *Node
       
   312 	aliases map[*Node]bool
       
   313 	terrors []string
       
   314 
       
   315 	stringMapType  reflect.Type
       
   316 	generalMapType reflect.Type
       
   317 
       
   318 	knownFields bool
       
   319 	uniqueKeys  bool
       
   320 	decodeCount int
       
   321 	aliasCount  int
       
   322 	aliasDepth  int
       
   323 }
       
   324 
       
   325 var (
       
   326 	nodeType       = reflect.TypeOf(Node{})
       
   327 	durationType   = reflect.TypeOf(time.Duration(0))
       
   328 	stringMapType  = reflect.TypeOf(map[string]interface{}{})
       
   329 	generalMapType = reflect.TypeOf(map[interface{}]interface{}{})
       
   330 	ifaceType      = generalMapType.Elem()
       
   331 	timeType       = reflect.TypeOf(time.Time{})
       
   332 	ptrTimeType    = reflect.TypeOf(&time.Time{})
       
   333 )
       
   334 
       
   335 func newDecoder() *decoder {
       
   336 	d := &decoder{
       
   337 		stringMapType:  stringMapType,
       
   338 		generalMapType: generalMapType,
       
   339 		uniqueKeys:     true,
       
   340 	}
       
   341 	d.aliases = make(map[*Node]bool)
       
   342 	return d
       
   343 }
       
   344 
       
   345 func (d *decoder) terror(n *Node, tag string, out reflect.Value) {
       
   346 	if n.Tag != "" {
       
   347 		tag = n.Tag
       
   348 	}
       
   349 	value := n.Value
       
   350 	if tag != seqTag && tag != mapTag {
       
   351 		if len(value) > 10 {
       
   352 			value = " `" + value[:7] + "...`"
       
   353 		} else {
       
   354 			value = " `" + value + "`"
       
   355 		}
       
   356 	}
       
   357 	d.terrors = append(d.terrors, fmt.Sprintf("line %d: cannot unmarshal %s%s into %s", n.Line, shortTag(tag), value, out.Type()))
       
   358 }
       
   359 
       
   360 func (d *decoder) callUnmarshaler(n *Node, u Unmarshaler) (good bool) {
       
   361 	err := u.UnmarshalYAML(n)
       
   362 	if e, ok := err.(*TypeError); ok {
       
   363 		d.terrors = append(d.terrors, e.Errors...)
       
   364 		return false
       
   365 	}
       
   366 	if err != nil {
       
   367 		fail(err)
       
   368 	}
       
   369 	return true
       
   370 }
       
   371 
       
   372 func (d *decoder) callObsoleteUnmarshaler(n *Node, u obsoleteUnmarshaler) (good bool) {
       
   373 	terrlen := len(d.terrors)
       
   374 	err := u.UnmarshalYAML(func(v interface{}) (err error) {
       
   375 		defer handleErr(&err)
       
   376 		d.unmarshal(n, reflect.ValueOf(v))
       
   377 		if len(d.terrors) > terrlen {
       
   378 			issues := d.terrors[terrlen:]
       
   379 			d.terrors = d.terrors[:terrlen]
       
   380 			return &TypeError{issues}
       
   381 		}
       
   382 		return nil
       
   383 	})
       
   384 	if e, ok := err.(*TypeError); ok {
       
   385 		d.terrors = append(d.terrors, e.Errors...)
       
   386 		return false
       
   387 	}
       
   388 	if err != nil {
       
   389 		fail(err)
       
   390 	}
       
   391 	return true
       
   392 }
       
   393 
       
   394 // d.prepare initializes and dereferences pointers and calls UnmarshalYAML
       
   395 // if a value is found to implement it.
       
   396 // It returns the initialized and dereferenced out value, whether
       
   397 // unmarshalling was already done by UnmarshalYAML, and if so whether
       
   398 // its types unmarshalled appropriately.
       
   399 //
       
   400 // If n holds a null value, prepare returns before doing anything.
       
   401 func (d *decoder) prepare(n *Node, out reflect.Value) (newout reflect.Value, unmarshaled, good bool) {
       
   402 	if n.ShortTag() == nullTag {
       
   403 		return out, false, false
       
   404 	}
       
   405 	again := true
       
   406 	for again {
       
   407 		again = false
       
   408 		if out.Kind() == reflect.Ptr {
       
   409 			if out.IsNil() {
       
   410 				out.Set(reflect.New(out.Type().Elem()))
       
   411 			}
       
   412 			out = out.Elem()
       
   413 			again = true
       
   414 		}
       
   415 		if out.CanAddr() {
       
   416 			outi := out.Addr().Interface()
       
   417 			if u, ok := outi.(Unmarshaler); ok {
       
   418 				good = d.callUnmarshaler(n, u)
       
   419 				return out, true, good
       
   420 			}
       
   421 			if u, ok := outi.(obsoleteUnmarshaler); ok {
       
   422 				good = d.callObsoleteUnmarshaler(n, u)
       
   423 				return out, true, good
       
   424 			}
       
   425 		}
       
   426 	}
       
   427 	return out, false, false
       
   428 }
       
   429 
       
   430 func (d *decoder) fieldByIndex(n *Node, v reflect.Value, index []int) (field reflect.Value) {
       
   431 	if n.ShortTag() == nullTag {
       
   432 		return reflect.Value{}
       
   433 	}
       
   434 	for _, num := range index {
       
   435 		for {
       
   436 			if v.Kind() == reflect.Ptr {
       
   437 				if v.IsNil() {
       
   438 					v.Set(reflect.New(v.Type().Elem()))
       
   439 				}
       
   440 				v = v.Elem()
       
   441 				continue
       
   442 			}
       
   443 			break
       
   444 		}
       
   445 		v = v.Field(num)
       
   446 	}
       
   447 	return v
       
   448 }
       
   449 
       
   450 const (
       
   451 	// 400,000 decode operations is ~500kb of dense object declarations, or
       
   452 	// ~5kb of dense object declarations with 10000% alias expansion
       
   453 	alias_ratio_range_low = 400000
       
   454 
       
   455 	// 4,000,000 decode operations is ~5MB of dense object declarations, or
       
   456 	// ~4.5MB of dense object declarations with 10% alias expansion
       
   457 	alias_ratio_range_high = 4000000
       
   458 
       
   459 	// alias_ratio_range is the range over which we scale allowed alias ratios
       
   460 	alias_ratio_range = float64(alias_ratio_range_high - alias_ratio_range_low)
       
   461 )
       
   462 
       
   463 func allowedAliasRatio(decodeCount int) float64 {
       
   464 	switch {
       
   465 	case decodeCount <= alias_ratio_range_low:
       
   466 		// allow 99% to come from alias expansion for small-to-medium documents
       
   467 		return 0.99
       
   468 	case decodeCount >= alias_ratio_range_high:
       
   469 		// allow 10% to come from alias expansion for very large documents
       
   470 		return 0.10
       
   471 	default:
       
   472 		// scale smoothly from 99% down to 10% over the range.
       
   473 		// this maps to 396,000 - 400,000 allowed alias-driven decodes over the range.
       
   474 		// 400,000 decode operations is ~100MB of allocations in worst-case scenarios (single-item maps).
       
   475 		return 0.99 - 0.89*(float64(decodeCount-alias_ratio_range_low)/alias_ratio_range)
       
   476 	}
       
   477 }
       
   478 
       
   479 func (d *decoder) unmarshal(n *Node, out reflect.Value) (good bool) {
       
   480 	d.decodeCount++
       
   481 	if d.aliasDepth > 0 {
       
   482 		d.aliasCount++
       
   483 	}
       
   484 	if d.aliasCount > 100 && d.decodeCount > 1000 && float64(d.aliasCount)/float64(d.decodeCount) > allowedAliasRatio(d.decodeCount) {
       
   485 		failf("document contains excessive aliasing")
       
   486 	}
       
   487 	if out.Type() == nodeType {
       
   488 		out.Set(reflect.ValueOf(n).Elem())
       
   489 		return true
       
   490 	}
       
   491 	switch n.Kind {
       
   492 	case DocumentNode:
       
   493 		return d.document(n, out)
       
   494 	case AliasNode:
       
   495 		return d.alias(n, out)
       
   496 	}
       
   497 	out, unmarshaled, good := d.prepare(n, out)
       
   498 	if unmarshaled {
       
   499 		return good
       
   500 	}
       
   501 	switch n.Kind {
       
   502 	case ScalarNode:
       
   503 		good = d.scalar(n, out)
       
   504 	case MappingNode:
       
   505 		good = d.mapping(n, out)
       
   506 	case SequenceNode:
       
   507 		good = d.sequence(n, out)
       
   508 	case 0:
       
   509 		if n.IsZero() {
       
   510 			return d.null(out)
       
   511 		}
       
   512 		fallthrough
       
   513 	default:
       
   514 		failf("cannot decode node with unknown kind %d", n.Kind)
       
   515 	}
       
   516 	return good
       
   517 }
       
   518 
       
   519 func (d *decoder) document(n *Node, out reflect.Value) (good bool) {
       
   520 	if len(n.Content) == 1 {
       
   521 		d.doc = n
       
   522 		d.unmarshal(n.Content[0], out)
       
   523 		return true
       
   524 	}
       
   525 	return false
       
   526 }
       
   527 
       
   528 func (d *decoder) alias(n *Node, out reflect.Value) (good bool) {
       
   529 	if d.aliases[n] {
       
   530 		// TODO this could actually be allowed in some circumstances.
       
   531 		failf("anchor '%s' value contains itself", n.Value)
       
   532 	}
       
   533 	d.aliases[n] = true
       
   534 	d.aliasDepth++
       
   535 	good = d.unmarshal(n.Alias, out)
       
   536 	d.aliasDepth--
       
   537 	delete(d.aliases, n)
       
   538 	return good
       
   539 }
       
   540 
       
   541 var zeroValue reflect.Value
       
   542 
       
   543 func resetMap(out reflect.Value) {
       
   544 	for _, k := range out.MapKeys() {
       
   545 		out.SetMapIndex(k, zeroValue)
       
   546 	}
       
   547 }
       
   548 
       
   549 func (d *decoder) null(out reflect.Value) bool {
       
   550 	if out.CanAddr() {
       
   551 		switch out.Kind() {
       
   552 		case reflect.Interface, reflect.Ptr, reflect.Map, reflect.Slice:
       
   553 			out.Set(reflect.Zero(out.Type()))
       
   554 			return true
       
   555 		}
       
   556 	}
       
   557 	return false
       
   558 }
       
   559 
       
   560 func (d *decoder) scalar(n *Node, out reflect.Value) bool {
       
   561 	var tag string
       
   562 	var resolved interface{}
       
   563 	if n.indicatedString() {
       
   564 		tag = strTag
       
   565 		resolved = n.Value
       
   566 	} else {
       
   567 		tag, resolved = resolve(n.Tag, n.Value)
       
   568 		if tag == binaryTag {
       
   569 			data, err := base64.StdEncoding.DecodeString(resolved.(string))
       
   570 			if err != nil {
       
   571 				failf("!!binary value contains invalid base64 data")
       
   572 			}
       
   573 			resolved = string(data)
       
   574 		}
       
   575 	}
       
   576 	if resolved == nil {
       
   577 		return d.null(out)
       
   578 	}
       
   579 	if resolvedv := reflect.ValueOf(resolved); out.Type() == resolvedv.Type() {
       
   580 		// We've resolved to exactly the type we want, so use that.
       
   581 		out.Set(resolvedv)
       
   582 		return true
       
   583 	}
       
   584 	// Perhaps we can use the value as a TextUnmarshaler to
       
   585 	// set its value.
       
   586 	if out.CanAddr() {
       
   587 		u, ok := out.Addr().Interface().(encoding.TextUnmarshaler)
       
   588 		if ok {
       
   589 			var text []byte
       
   590 			if tag == binaryTag {
       
   591 				text = []byte(resolved.(string))
       
   592 			} else {
       
   593 				// We let any value be unmarshaled into TextUnmarshaler.
       
   594 				// That might be more lax than we'd like, but the
       
   595 				// TextUnmarshaler itself should bowl out any dubious values.
       
   596 				text = []byte(n.Value)
       
   597 			}
       
   598 			err := u.UnmarshalText(text)
       
   599 			if err != nil {
       
   600 				fail(err)
       
   601 			}
       
   602 			return true
       
   603 		}
       
   604 	}
       
   605 	switch out.Kind() {
       
   606 	case reflect.String:
       
   607 		if tag == binaryTag {
       
   608 			out.SetString(resolved.(string))
       
   609 			return true
       
   610 		}
       
   611 		out.SetString(n.Value)
       
   612 		return true
       
   613 	case reflect.Interface:
       
   614 		out.Set(reflect.ValueOf(resolved))
       
   615 		return true
       
   616 	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
       
   617 		// This used to work in v2, but it's very unfriendly.
       
   618 		isDuration := out.Type() == durationType
       
   619 
       
   620 		switch resolved := resolved.(type) {
       
   621 		case int:
       
   622 			if !isDuration && !out.OverflowInt(int64(resolved)) {
       
   623 				out.SetInt(int64(resolved))
       
   624 				return true
       
   625 			}
       
   626 		case int64:
       
   627 			if !isDuration && !out.OverflowInt(resolved) {
       
   628 				out.SetInt(resolved)
       
   629 				return true
       
   630 			}
       
   631 		case uint64:
       
   632 			if !isDuration && resolved <= math.MaxInt64 && !out.OverflowInt(int64(resolved)) {
       
   633 				out.SetInt(int64(resolved))
       
   634 				return true
       
   635 			}
       
   636 		case float64:
       
   637 			if !isDuration && resolved <= math.MaxInt64 && !out.OverflowInt(int64(resolved)) {
       
   638 				out.SetInt(int64(resolved))
       
   639 				return true
       
   640 			}
       
   641 		case string:
       
   642 			if out.Type() == durationType {
       
   643 				d, err := time.ParseDuration(resolved)
       
   644 				if err == nil {
       
   645 					out.SetInt(int64(d))
       
   646 					return true
       
   647 				}
       
   648 			}
       
   649 		}
       
   650 	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
       
   651 		switch resolved := resolved.(type) {
       
   652 		case int:
       
   653 			if resolved >= 0 && !out.OverflowUint(uint64(resolved)) {
       
   654 				out.SetUint(uint64(resolved))
       
   655 				return true
       
   656 			}
       
   657 		case int64:
       
   658 			if resolved >= 0 && !out.OverflowUint(uint64(resolved)) {
       
   659 				out.SetUint(uint64(resolved))
       
   660 				return true
       
   661 			}
       
   662 		case uint64:
       
   663 			if !out.OverflowUint(uint64(resolved)) {
       
   664 				out.SetUint(uint64(resolved))
       
   665 				return true
       
   666 			}
       
   667 		case float64:
       
   668 			if resolved <= math.MaxUint64 && !out.OverflowUint(uint64(resolved)) {
       
   669 				out.SetUint(uint64(resolved))
       
   670 				return true
       
   671 			}
       
   672 		}
       
   673 	case reflect.Bool:
       
   674 		switch resolved := resolved.(type) {
       
   675 		case bool:
       
   676 			out.SetBool(resolved)
       
   677 			return true
       
   678 		case string:
       
   679 			// This offers some compatibility with the 1.1 spec (https://yaml.org/type/bool.html).
       
   680 			// It only works if explicitly attempting to unmarshal into a typed bool value.
       
   681 			switch resolved {
       
   682 			case "y", "Y", "yes", "Yes", "YES", "on", "On", "ON":
       
   683 				out.SetBool(true)
       
   684 				return true
       
   685 			case "n", "N", "no", "No", "NO", "off", "Off", "OFF":
       
   686 				out.SetBool(false)
       
   687 				return true
       
   688 			}
       
   689 		}
       
   690 	case reflect.Float32, reflect.Float64:
       
   691 		switch resolved := resolved.(type) {
       
   692 		case int:
       
   693 			out.SetFloat(float64(resolved))
       
   694 			return true
       
   695 		case int64:
       
   696 			out.SetFloat(float64(resolved))
       
   697 			return true
       
   698 		case uint64:
       
   699 			out.SetFloat(float64(resolved))
       
   700 			return true
       
   701 		case float64:
       
   702 			out.SetFloat(resolved)
       
   703 			return true
       
   704 		}
       
   705 	case reflect.Struct:
       
   706 		if resolvedv := reflect.ValueOf(resolved); out.Type() == resolvedv.Type() {
       
   707 			out.Set(resolvedv)
       
   708 			return true
       
   709 		}
       
   710 	case reflect.Ptr:
       
   711 		panic("yaml internal error: please report the issue")
       
   712 	}
       
   713 	d.terror(n, tag, out)
       
   714 	return false
       
   715 }
       
   716 
       
   717 func settableValueOf(i interface{}) reflect.Value {
       
   718 	v := reflect.ValueOf(i)
       
   719 	sv := reflect.New(v.Type()).Elem()
       
   720 	sv.Set(v)
       
   721 	return sv
       
   722 }
       
   723 
       
   724 func (d *decoder) sequence(n *Node, out reflect.Value) (good bool) {
       
   725 	l := len(n.Content)
       
   726 
       
   727 	var iface reflect.Value
       
   728 	switch out.Kind() {
       
   729 	case reflect.Slice:
       
   730 		out.Set(reflect.MakeSlice(out.Type(), l, l))
       
   731 	case reflect.Array:
       
   732 		if l != out.Len() {
       
   733 			failf("invalid array: want %d elements but got %d", out.Len(), l)
       
   734 		}
       
   735 	case reflect.Interface:
       
   736 		// No type hints. Will have to use a generic sequence.
       
   737 		iface = out
       
   738 		out = settableValueOf(make([]interface{}, l))
       
   739 	default:
       
   740 		d.terror(n, seqTag, out)
       
   741 		return false
       
   742 	}
       
   743 	et := out.Type().Elem()
       
   744 
       
   745 	j := 0
       
   746 	for i := 0; i < l; i++ {
       
   747 		e := reflect.New(et).Elem()
       
   748 		if ok := d.unmarshal(n.Content[i], e); ok {
       
   749 			out.Index(j).Set(e)
       
   750 			j++
       
   751 		}
       
   752 	}
       
   753 	if out.Kind() != reflect.Array {
       
   754 		out.Set(out.Slice(0, j))
       
   755 	}
       
   756 	if iface.IsValid() {
       
   757 		iface.Set(out)
       
   758 	}
       
   759 	return true
       
   760 }
       
   761 
       
   762 func (d *decoder) mapping(n *Node, out reflect.Value) (good bool) {
       
   763 	l := len(n.Content)
       
   764 	if d.uniqueKeys {
       
   765 		nerrs := len(d.terrors)
       
   766 		for i := 0; i < l; i += 2 {
       
   767 			ni := n.Content[i]
       
   768 			for j := i + 2; j < l; j += 2 {
       
   769 				nj := n.Content[j]
       
   770 				if ni.Kind == nj.Kind && ni.Value == nj.Value {
       
   771 					d.terrors = append(d.terrors, fmt.Sprintf("line %d: mapping key %#v already defined at line %d", nj.Line, nj.Value, ni.Line))
       
   772 				}
       
   773 			}
       
   774 		}
       
   775 		if len(d.terrors) > nerrs {
       
   776 			return false
       
   777 		}
       
   778 	}
       
   779 	switch out.Kind() {
       
   780 	case reflect.Struct:
       
   781 		return d.mappingStruct(n, out)
       
   782 	case reflect.Map:
       
   783 		// okay
       
   784 	case reflect.Interface:
       
   785 		iface := out
       
   786 		if isStringMap(n) {
       
   787 			out = reflect.MakeMap(d.stringMapType)
       
   788 		} else {
       
   789 			out = reflect.MakeMap(d.generalMapType)
       
   790 		}
       
   791 		iface.Set(out)
       
   792 	default:
       
   793 		d.terror(n, mapTag, out)
       
   794 		return false
       
   795 	}
       
   796 
       
   797 	outt := out.Type()
       
   798 	kt := outt.Key()
       
   799 	et := outt.Elem()
       
   800 
       
   801 	stringMapType := d.stringMapType
       
   802 	generalMapType := d.generalMapType
       
   803 	if outt.Elem() == ifaceType {
       
   804 		if outt.Key().Kind() == reflect.String {
       
   805 			d.stringMapType = outt
       
   806 		} else if outt.Key() == ifaceType {
       
   807 			d.generalMapType = outt
       
   808 		}
       
   809 	}
       
   810 
       
   811 	mapIsNew := false
       
   812 	if out.IsNil() {
       
   813 		out.Set(reflect.MakeMap(outt))
       
   814 		mapIsNew = true
       
   815 	}
       
   816 	for i := 0; i < l; i += 2 {
       
   817 		if isMerge(n.Content[i]) {
       
   818 			d.merge(n.Content[i+1], out)
       
   819 			continue
       
   820 		}
       
   821 		k := reflect.New(kt).Elem()
       
   822 		if d.unmarshal(n.Content[i], k) {
       
   823 			kkind := k.Kind()
       
   824 			if kkind == reflect.Interface {
       
   825 				kkind = k.Elem().Kind()
       
   826 			}
       
   827 			if kkind == reflect.Map || kkind == reflect.Slice {
       
   828 				failf("invalid map key: %#v", k.Interface())
       
   829 			}
       
   830 			e := reflect.New(et).Elem()
       
   831 			if d.unmarshal(n.Content[i+1], e) || n.Content[i+1].ShortTag() == nullTag && (mapIsNew || !out.MapIndex(k).IsValid()) {
       
   832 				out.SetMapIndex(k, e)
       
   833 			}
       
   834 		}
       
   835 	}
       
   836 	d.stringMapType = stringMapType
       
   837 	d.generalMapType = generalMapType
       
   838 	return true
       
   839 }
       
   840 
       
   841 func isStringMap(n *Node) bool {
       
   842 	if n.Kind != MappingNode {
       
   843 		return false
       
   844 	}
       
   845 	l := len(n.Content)
       
   846 	for i := 0; i < l; i += 2 {
       
   847 		if n.Content[i].ShortTag() != strTag {
       
   848 			return false
       
   849 		}
       
   850 	}
       
   851 	return true
       
   852 }
       
   853 
       
   854 func (d *decoder) mappingStruct(n *Node, out reflect.Value) (good bool) {
       
   855 	sinfo, err := getStructInfo(out.Type())
       
   856 	if err != nil {
       
   857 		panic(err)
       
   858 	}
       
   859 
       
   860 	var inlineMap reflect.Value
       
   861 	var elemType reflect.Type
       
   862 	if sinfo.InlineMap != -1 {
       
   863 		inlineMap = out.Field(sinfo.InlineMap)
       
   864 		inlineMap.Set(reflect.New(inlineMap.Type()).Elem())
       
   865 		elemType = inlineMap.Type().Elem()
       
   866 	}
       
   867 
       
   868 	for _, index := range sinfo.InlineUnmarshalers {
       
   869 		field := d.fieldByIndex(n, out, index)
       
   870 		d.prepare(n, field)
       
   871 	}
       
   872 
       
   873 	var doneFields []bool
       
   874 	if d.uniqueKeys {
       
   875 		doneFields = make([]bool, len(sinfo.FieldsList))
       
   876 	}
       
   877 	name := settableValueOf("")
       
   878 	l := len(n.Content)
       
   879 	for i := 0; i < l; i += 2 {
       
   880 		ni := n.Content[i]
       
   881 		if isMerge(ni) {
       
   882 			d.merge(n.Content[i+1], out)
       
   883 			continue
       
   884 		}
       
   885 		if !d.unmarshal(ni, name) {
       
   886 			continue
       
   887 		}
       
   888 		if info, ok := sinfo.FieldsMap[name.String()]; ok {
       
   889 			if d.uniqueKeys {
       
   890 				if doneFields[info.Id] {
       
   891 					d.terrors = append(d.terrors, fmt.Sprintf("line %d: field %s already set in type %s", ni.Line, name.String(), out.Type()))
       
   892 					continue
       
   893 				}
       
   894 				doneFields[info.Id] = true
       
   895 			}
       
   896 			var field reflect.Value
       
   897 			if info.Inline == nil {
       
   898 				field = out.Field(info.Num)
       
   899 			} else {
       
   900 				field = d.fieldByIndex(n, out, info.Inline)
       
   901 			}
       
   902 			d.unmarshal(n.Content[i+1], field)
       
   903 		} else if sinfo.InlineMap != -1 {
       
   904 			if inlineMap.IsNil() {
       
   905 				inlineMap.Set(reflect.MakeMap(inlineMap.Type()))
       
   906 			}
       
   907 			value := reflect.New(elemType).Elem()
       
   908 			d.unmarshal(n.Content[i+1], value)
       
   909 			inlineMap.SetMapIndex(name, value)
       
   910 		} else if d.knownFields {
       
   911 			d.terrors = append(d.terrors, fmt.Sprintf("line %d: field %s not found in type %s", ni.Line, name.String(), out.Type()))
       
   912 		}
       
   913 	}
       
   914 	return true
       
   915 }
       
   916 
       
   917 func failWantMap() {
       
   918 	failf("map merge requires map or sequence of maps as the value")
       
   919 }
       
   920 
       
   921 func (d *decoder) merge(n *Node, out reflect.Value) {
       
   922 	switch n.Kind {
       
   923 	case MappingNode:
       
   924 		d.unmarshal(n, out)
       
   925 	case AliasNode:
       
   926 		if n.Alias != nil && n.Alias.Kind != MappingNode {
       
   927 			failWantMap()
       
   928 		}
       
   929 		d.unmarshal(n, out)
       
   930 	case SequenceNode:
       
   931 		// Step backwards as earlier nodes take precedence.
       
   932 		for i := len(n.Content) - 1; i >= 0; i-- {
       
   933 			ni := n.Content[i]
       
   934 			if ni.Kind == AliasNode {
       
   935 				if ni.Alias != nil && ni.Alias.Kind != MappingNode {
       
   936 					failWantMap()
       
   937 				}
       
   938 			} else if ni.Kind != MappingNode {
       
   939 				failWantMap()
       
   940 			}
       
   941 			d.unmarshal(ni, out)
       
   942 		}
       
   943 	default:
       
   944 		failWantMap()
       
   945 	}
       
   946 }
       
   947 
       
   948 func isMerge(n *Node) bool {
       
   949 	return n.Kind == ScalarNode && n.Value == "<<" && (n.Tag == "" || n.Tag == "!" || shortTag(n.Tag) == mergeTag)
       
   950 }