tea/vendor/gopkg.in/yaml.v3/decode.go

932 lines
23 KiB
Go

//
// Copyright (c) 2011-2019 Canonical Ltd
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package yaml
import (
"encoding"
"encoding/base64"
"fmt"
"io"
"math"
"reflect"
"strconv"
"time"
)
// ----------------------------------------------------------------------------
// Parser, produces a node tree out of a libyaml event stream.
type parser struct {
parser yaml_parser_t
event yaml_event_t
doc *Node
anchors map[string]*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.anchors = make(map[string]*Node)
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 {
n.Anchor = string(anchor)
p.anchors[n.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
case yaml_TAIL_COMMENT_EVENT:
panic("internal error: unexpected tail comment event (please report)")
default:
panic("internal error: attempted to parse unknown event (please report): " + p.event.typ.String())
}
}
func (p *parser) node(kind Kind, defaultTag, tag, value string) *Node {
var style Style
if tag != "" && tag != "!" {
tag = shortTag(tag)
style = TaggedStyle
} else if defaultTag != "" {
tag = defaultTag
} else if kind == ScalarNode {
tag, _ = resolve("", value)
}
return &Node{
Kind: kind,
Tag: tag,
Value: value,
Style: style,
Line: p.event.start_mark.line + 1,
Column: p.event.start_mark.column + 1,
HeadComment: string(p.event.head_comment),
LineComment: string(p.event.line_comment),
FootComment: string(p.event.foot_comment),
}
}
func (p *parser) parseChild(parent *Node) *Node {
child := p.parse()
parent.Content = append(parent.Content, child)
return child
}
func (p *parser) document() *Node {
n := p.node(DocumentNode, "", "", "")
p.doc = n
p.expect(yaml_DOCUMENT_START_EVENT)
p.parseChild(n)
if p.peek() == yaml_DOCUMENT_END_EVENT {
n.FootComment = string(p.event.foot_comment)
}
p.expect(yaml_DOCUMENT_END_EVENT)
return n
}
func (p *parser) alias() *Node {
n := p.node(AliasNode, "", "", string(p.event.anchor))
n.Alias = p.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 {
var parsedStyle = p.event.scalar_style()
var nodeStyle Style
switch {
case parsedStyle&yaml_DOUBLE_QUOTED_SCALAR_STYLE != 0:
nodeStyle = DoubleQuotedStyle
case parsedStyle&yaml_SINGLE_QUOTED_SCALAR_STYLE != 0:
nodeStyle = SingleQuotedStyle
case parsedStyle&yaml_LITERAL_SCALAR_STYLE != 0:
nodeStyle = LiteralStyle
case parsedStyle&yaml_FOLDED_SCALAR_STYLE != 0:
nodeStyle = FoldedStyle
}
var nodeValue = string(p.event.value)
var nodeTag = string(p.event.tag)
var defaultTag string
if nodeStyle == 0 {
if nodeValue == "<<" {
defaultTag = mergeTag
}
} else {
defaultTag = strTag
}
n := p.node(ScalarNode, defaultTag, nodeTag, nodeValue)
n.Style |= nodeStyle
p.anchor(n, p.event.anchor)
p.expect(yaml_SCALAR_EVENT)
return n
}
func (p *parser) sequence() *Node {
n := p.node(SequenceNode, seqTag, string(p.event.tag), "")
if p.event.sequence_style()&yaml_FLOW_SEQUENCE_STYLE != 0 {
n.Style |= FlowStyle
}
p.anchor(n, p.event.anchor)
p.expect(yaml_SEQUENCE_START_EVENT)
for p.peek() != yaml_SEQUENCE_END_EVENT {
p.parseChild(n)
}
n.LineComment = string(p.event.line_comment)
n.FootComment = string(p.event.foot_comment)
p.expect(yaml_SEQUENCE_END_EVENT)
return n
}
func (p *parser) mapping() *Node {
n := p.node(MappingNode, mapTag, string(p.event.tag), "")
block := true
if p.event.mapping_style()&yaml_FLOW_MAPPING_STYLE != 0 {
block = false
n.Style |= FlowStyle
}
p.anchor(n, p.event.anchor)
p.expect(yaml_MAPPING_START_EVENT)
for p.peek() != yaml_MAPPING_END_EVENT {
k := p.parseChild(n)
if block && k.FootComment != "" {
// Must be a foot comment for the prior value when being dedented.
if len(n.Content) > 2 {
n.Content[len(n.Content)-3].FootComment = k.FootComment
k.FootComment = ""
}
}
v := p.parseChild(n)
if k.FootComment == "" && v.FootComment != "" {
k.FootComment = v.FootComment
v.FootComment = ""
}
if p.peek() == yaml_TAIL_COMMENT_EVENT {
if k.FootComment == "" {
k.FootComment = string(p.event.foot_comment)
}
p.expect(yaml_TAIL_COMMENT_EVENT)
}
}
n.LineComment = string(p.event.line_comment)
n.FootComment = string(p.event.foot_comment)
if n.Style&FlowStyle == 0 && n.FootComment != "" && len(n.Content) > 1 {
n.Content[len(n.Content)-2].FootComment = n.FootComment
n.FootComment = ""
}
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
terrors []string
stringMapType reflect.Type
generalMapType reflect.Type
knownFields bool
uniqueKeys bool
decodeCount int
aliasCount int
aliasDepth int
}
var (
nodeType = reflect.TypeOf(Node{})
durationType = reflect.TypeOf(time.Duration(0))
stringMapType = reflect.TypeOf(map[string]interface{}{})
generalMapType = reflect.TypeOf(map[interface{}]interface{}{})
ifaceType = generalMapType.Elem()
timeType = reflect.TypeOf(time.Time{})
ptrTimeType = reflect.TypeOf(&time.Time{})
)
func newDecoder() *decoder {
d := &decoder{
stringMapType: stringMapType,
generalMapType: generalMapType,
uniqueKeys: true,
}
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 != seqTag && tag != mapTag {
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, shortTag(tag), value, out.Type()))
}
func (d *decoder) callUnmarshaler(n *Node, u Unmarshaler) (good bool) {
err := u.UnmarshalYAML(n)
if e, ok := err.(*TypeError); ok {
d.terrors = append(d.terrors, e.Errors...)
return false
}
if err != nil {
fail(err)
}
return true
}
func (d *decoder) callObsoleteUnmarshaler(n *Node, u obsoleteUnmarshaler) (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.ShortTag() == nullTag {
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() {
outi := out.Addr().Interface()
if u, ok := outi.(Unmarshaler); ok {
good = d.callUnmarshaler(n, u)
return out, true, good
}
if u, ok := outi.(obsoleteUnmarshaler); ok {
good = d.callObsoleteUnmarshaler(n, u)
return out, true, good
}
}
}
return out, false, false
}
func (d *decoder) fieldByIndex(n *Node, v reflect.Value, index []int) (field reflect.Value) {
if n.ShortTag() == nullTag {
return reflect.Value{}
}
for _, num := range index {
for {
if v.Kind() == reflect.Ptr {
if v.IsNil() {
v.Set(reflect.New(v.Type().Elem()))
}
v = v.Elem()
continue
}
break
}
v = v.Field(num)
}
return v
}
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")
}
if out.Type() == nodeType {
out.Set(reflect.ValueOf(n).Elem())
return true
}
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(int(n.Kind)))
}
return good
}
func (d *decoder) document(n *Node, out reflect.Value) (good bool) {
if len(n.Content) == 1 {
d.doc = n
d.unmarshal(n.Content[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.indicatedString() {
tag = strTag
resolved = n.Value
} else {
tag, resolved = resolve(n.Tag, n.Value)
if tag == binaryTag {
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.CanAddr() {
switch out.Kind() {
case reflect.Interface, reflect.Ptr, reflect.Map, reflect.Slice:
out.Set(reflect.Zero(out.Type()))
return true
}
}
return false
}
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 == binaryTag {
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 == binaryTag {
out.SetString(resolved.(string))
return true
}
out.SetString(n.Value)
return true
case reflect.Interface:
out.Set(reflect.ValueOf(resolved))
return true
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
// This used to work in v2, but it's very unfriendly.
isDuration := out.Type() == durationType
switch resolved := resolved.(type) {
case int:
if !isDuration && !out.OverflowInt(int64(resolved)) {
out.SetInt(int64(resolved))
return true
}
case int64:
if !isDuration && !out.OverflowInt(resolved) {
out.SetInt(resolved)
return true
}
case uint64:
if !isDuration && resolved <= math.MaxInt64 && !out.OverflowInt(int64(resolved)) {
out.SetInt(int64(resolved))
return true
}
case float64:
if !isDuration && 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 string:
// This offers some compatibility with the 1.1 spec (https://yaml.org/type/bool.html).
// It only works if explicitly attempting to unmarshal into a typed bool value.
switch resolved {
case "y", "Y", "yes", "Yes", "YES", "on", "On", "ON":
out.SetBool(true)
return true
case "n", "N", "no", "No", "NO", "off", "Off", "OFF":
out.SetBool(false)
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:
panic("yaml internal error: please report the issue")
}
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.Content)
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, seqTag, 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.Content[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) {
l := len(n.Content)
if d.uniqueKeys {
nerrs := len(d.terrors)
for i := 0; i < l; i += 2 {
ni := n.Content[i]
for j := i + 2; j < l; j += 2 {
nj := n.Content[j]
if ni.Kind == nj.Kind && ni.Value == nj.Value {
d.terrors = append(d.terrors, fmt.Sprintf("line %d: mapping key %#v already defined at line %d", nj.Line, nj.Value, ni.Line))
}
}
}
if len(d.terrors) > nerrs {
return false
}
}
switch out.Kind() {
case reflect.Struct:
return d.mappingStruct(n, out)
case reflect.Map:
// okay
case reflect.Interface:
iface := out
if isStringMap(n) {
out = reflect.MakeMap(d.stringMapType)
} else {
out = reflect.MakeMap(d.generalMapType)
}
iface.Set(out)
default:
d.terror(n, mapTag, out)
return false
}
outt := out.Type()
kt := outt.Key()
et := outt.Elem()
stringMapType := d.stringMapType
generalMapType := d.generalMapType
if outt.Elem() == ifaceType {
if outt.Key().Kind() == reflect.String {
d.stringMapType = outt
} else if outt.Key() == ifaceType {
d.generalMapType = outt
}
}
if out.IsNil() {
out.Set(reflect.MakeMap(outt))
}
for i := 0; i < l; i += 2 {
if isMerge(n.Content[i]) {
d.merge(n.Content[i+1], out)
continue
}
k := reflect.New(kt).Elem()
if d.unmarshal(n.Content[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.Content[i+1], e) {
out.SetMapIndex(k, e)
}
}
}
d.stringMapType = stringMapType
d.generalMapType = generalMapType
return true
}
func isStringMap(n *Node) bool {
if n.Kind != MappingNode {
return false
}
l := len(n.Content)
for i := 0; i < l; i += 2 {
if n.Content[i].ShortTag() != strTag {
return false
}
}
return true
}
func (d *decoder) mappingStruct(n *Node, out reflect.Value) (good bool) {
sinfo, err := getStructInfo(out.Type())
if err != nil {
panic(err)
}
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()
}
for _, index := range sinfo.InlineUnmarshalers {
field := d.fieldByIndex(n, out, index)
d.prepare(n, field)
}
var doneFields []bool
if d.uniqueKeys {
doneFields = make([]bool, len(sinfo.FieldsList))
}
name := settableValueOf("")
l := len(n.Content)
for i := 0; i < l; i += 2 {
ni := n.Content[i]
if isMerge(ni) {
d.merge(n.Content[i+1], out)
continue
}
if !d.unmarshal(ni, name) {
continue
}
if info, ok := sinfo.FieldsMap[name.String()]; ok {
if d.uniqueKeys {
if doneFields[info.Id] {
d.terrors = append(d.terrors, fmt.Sprintf("line %d: field %s already set in type %s", ni.Line, name.String(), out.Type()))
continue
}
doneFields[info.Id] = true
}
var field reflect.Value
if info.Inline == nil {
field = out.Field(info.Num)
} else {
field = d.fieldByIndex(n, out, info.Inline)
}
d.unmarshal(n.Content[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.Content[i+1], value)
inlineMap.SetMapIndex(name, value)
} else if d.knownFields {
d.terrors = append(d.terrors, fmt.Sprintf("line %d: field %s not found in type %s", ni.Line, 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.Content) - 1; i >= 0; i-- {
ni := n.Content[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.Tag == "" || n.Tag == "!" || shortTag(n.Tag) == mergeTag)
}