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Go

// Copyright 2011-2019 Canonical Ltd
// Copyright 2025 The go-yaml Project Contributors
// SPDX-License-Identifier: Apache-2.0
// Representer stage: Converts Go values to YAML nodes.
// Handles marshaling from Go types to the intermediate node representation.
package libyaml
import (
"encoding"
"fmt"
"io"
"reflect"
"regexp"
"sort"
"strconv"
"strings"
"time"
"unicode"
"unicode/utf8"
)
type keyList []reflect.Value
func (l keyList) Len() int { return len(l) }
func (l keyList) Swap(i, j int) { l[i], l[j] = l[j], l[i] }
func (l keyList) Less(i, j int) bool {
a := l[i]
b := l[j]
ak := a.Kind()
bk := b.Kind()
for (ak == reflect.Interface || ak == reflect.Pointer) && !a.IsNil() {
a = a.Elem()
ak = a.Kind()
}
for (bk == reflect.Interface || bk == reflect.Pointer) && !b.IsNil() {
b = b.Elem()
bk = b.Kind()
}
af, aok := keyFloat(a)
bf, bok := keyFloat(b)
if aok && bok {
if af != bf {
return af < bf
}
if ak != bk {
return ak < bk
}
return numLess(a, b)
}
if ak != reflect.String || bk != reflect.String {
return ak < bk
}
ar, br := []rune(a.String()), []rune(b.String())
digits := false
for i := 0; i < len(ar) && i < len(br); i++ {
if ar[i] == br[i] {
digits = unicode.IsDigit(ar[i])
continue
}
al := unicode.IsLetter(ar[i])
bl := unicode.IsLetter(br[i])
if al && bl {
return ar[i] < br[i]
}
if al || bl {
if digits {
return al
} else {
return bl
}
}
var ai, bi int
var an, bn int64
if ar[i] == '0' || br[i] == '0' {
for j := i - 1; j >= 0 && unicode.IsDigit(ar[j]); j-- {
if ar[j] != '0' {
an = 1
bn = 1
break
}
}
}
for ai = i; ai < len(ar) && unicode.IsDigit(ar[ai]); ai++ {
an = an*10 + int64(ar[ai]-'0')
}
for bi = i; bi < len(br) && unicode.IsDigit(br[bi]); bi++ {
bn = bn*10 + int64(br[bi]-'0')
}
if an != bn {
return an < bn
}
if ai != bi {
return ai < bi
}
return ar[i] < br[i]
}
return len(ar) < len(br)
}
// keyFloat returns a float value for v if it is a number/bool
// and whether it is a number/bool or not.
func keyFloat(v reflect.Value) (f float64, ok bool) {
switch v.Kind() {
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
return float64(v.Int()), true
case reflect.Float32, reflect.Float64:
return v.Float(), true
case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
return float64(v.Uint()), true
case reflect.Bool:
if v.Bool() {
return 1, true
}
return 0, true
}
return 0, false
}
// numLess returns whether a < b.
// a and b must necessarily have the same kind.
func numLess(a, b reflect.Value) bool {
switch a.Kind() {
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
return a.Int() < b.Int()
case reflect.Float32, reflect.Float64:
return a.Float() < b.Float()
case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
return a.Uint() < b.Uint()
case reflect.Bool:
return !a.Bool() && b.Bool()
}
panic("not a number")
}
// Sentinel values for newRepresenter parameters.
// These provide clarity at call sites, similar to http.NoBody.
var (
noWriter io.Writer = nil
noVersionDirective *VersionDirective = nil
noTagDirective []TagDirective = nil
)
type Representer struct {
Emitter Emitter
Out []byte
flow bool
Indent int
lineWidth int
doneInit bool
explicitStart bool
explicitEnd bool
flowSimpleCollections bool
quotePreference QuoteStyle
}
// NewRepresenter creates a new YAML representr with the given options.
//
// The writer parameter specifies the output destination for the representr.
// If writer is nil, the representr will write to an internal buffer.
func NewRepresenter(writer io.Writer, opts *Options) *Representer {
emitter := NewEmitter()
emitter.CompactSequenceIndent = opts.CompactSeqIndent
emitter.quotePreference = opts.QuotePreference
emitter.SetWidth(opts.LineWidth)
emitter.SetUnicode(opts.Unicode)
emitter.SetCanonical(opts.Canonical)
emitter.SetLineBreak(opts.LineBreak)
r := &Representer{
Emitter: emitter,
Indent: opts.Indent,
lineWidth: opts.LineWidth,
explicitStart: opts.ExplicitStart,
explicitEnd: opts.ExplicitEnd,
flowSimpleCollections: opts.FlowSimpleCollections,
quotePreference: opts.QuotePreference,
}
if writer != nil {
r.Emitter.SetOutputWriter(writer)
} else {
r.Emitter.SetOutputString(&r.Out)
}
return r
}
func (r *Representer) init() {
if r.doneInit {
return
}
if r.Indent == 0 {
r.Indent = 4
}
r.Emitter.BestIndent = r.Indent
r.emit(NewStreamStartEvent(UTF8_ENCODING))
r.doneInit = true
}
func (r *Representer) Finish() {
r.Emitter.OpenEnded = false
r.emit(NewStreamEndEvent())
}
func (r *Representer) Destroy() {
r.Emitter.Delete()
}
func (r *Representer) emit(event Event) {
// This will internally delete the event value.
r.must(r.Emitter.Emit(&event))
}
func (r *Representer) must(err error) {
if err != nil {
msg := err.Error()
if msg == "" {
msg = "unknown problem generating YAML content"
}
failf("%s", msg)
}
}
func (r *Representer) MarshalDoc(tag string, in reflect.Value) {
r.init()
var node *Node
if in.IsValid() {
node, _ = in.Interface().(*Node)
}
if node != nil && node.Kind == DocumentNode {
r.nodev(in)
} else {
// Use !explicitStart for implicit flag (true = implicit/no marker)
r.emit(NewDocumentStartEvent(noVersionDirective, noTagDirective, !r.explicitStart))
r.marshal(tag, in)
// Use !explicitEnd for implicit flag
r.emit(NewDocumentEndEvent(!r.explicitEnd))
}
}
func (r *Representer) marshal(tag string, in reflect.Value) {
tag = shortTag(tag)
if !in.IsValid() || in.Kind() == reflect.Pointer && in.IsNil() {
r.nilv()
return
}
iface := in.Interface()
switch value := iface.(type) {
case *Node:
r.nodev(in)
return
case Node:
if !in.CanAddr() {
n := reflect.New(in.Type()).Elem()
n.Set(in)
in = n
}
r.nodev(in.Addr())
return
case time.Time:
r.timev(tag, in)
return
case *time.Time:
r.timev(tag, in.Elem())
return
case time.Duration:
r.stringv(tag, reflect.ValueOf(value.String()))
return
case Marshaler:
v, err := value.MarshalYAML()
if err != nil {
Fail(err)
}
if v == nil {
r.nilv()
return
}
r.marshal(tag, reflect.ValueOf(v))
return
case encoding.TextMarshaler:
text, err := value.MarshalText()
if err != nil {
Fail(err)
}
in = reflect.ValueOf(string(text))
case nil:
r.nilv()
return
}
switch in.Kind() {
case reflect.Interface:
r.marshal(tag, in.Elem())
case reflect.Map:
r.mapv(tag, in)
case reflect.Pointer:
r.marshal(tag, in.Elem())
case reflect.Struct:
r.structv(tag, in)
case reflect.Slice, reflect.Array:
r.slicev(tag, in)
case reflect.String:
r.stringv(tag, in)
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
r.intv(tag, in)
case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
r.uintv(tag, in)
case reflect.Float32, reflect.Float64:
r.floatv(tag, in)
case reflect.Bool:
r.boolv(tag, in)
default:
panic("cannot marshal type: " + in.Type().String())
}
}
func (r *Representer) mapv(tag string, in reflect.Value) {
r.mappingv(tag, func() {
keys := keyList(in.MapKeys())
sort.Sort(keys)
for _, k := range keys {
r.marshal("", k)
r.marshal("", in.MapIndex(k))
}
})
}
func (r *Representer) fieldByIndex(v reflect.Value, index []int) (field reflect.Value) {
for _, num := range index {
for {
if v.Kind() == reflect.Pointer {
if v.IsNil() {
return reflect.Value{}
}
v = v.Elem()
continue
}
break
}
v = v.Field(num)
}
return v
}
func (r *Representer) structv(tag string, in reflect.Value) {
sinfo, err := getStructInfo(in.Type())
if err != nil {
panic(err)
}
r.mappingv(tag, func() {
for _, info := range sinfo.FieldsList {
var value reflect.Value
if info.Inline == nil {
value = in.Field(info.Num)
} else {
value = r.fieldByIndex(in, info.Inline)
if !value.IsValid() {
continue
}
}
if info.OmitEmpty && isZero(value) {
continue
}
r.marshal("", reflect.ValueOf(info.Key))
r.flow = info.Flow
r.marshal("", value)
}
if sinfo.InlineMap >= 0 {
m := in.Field(sinfo.InlineMap)
if m.Len() > 0 {
r.flow = false
keys := keyList(m.MapKeys())
sort.Sort(keys)
for _, k := range keys {
if _, found := sinfo.FieldsMap[k.String()]; found {
panic(fmt.Sprintf("cannot have key %q in inlined map: conflicts with struct field", k.String()))
}
r.marshal("", k)
r.flow = false
r.marshal("", m.MapIndex(k))
}
}
}
})
}
func (r *Representer) mappingv(tag string, f func()) {
implicit := tag == ""
style := BLOCK_MAPPING_STYLE
if r.flow {
r.flow = false
style = FLOW_MAPPING_STYLE
}
r.emit(NewMappingStartEvent(nil, []byte(tag), implicit, style))
f()
r.emit(NewMappingEndEvent())
}
func (r *Representer) slicev(tag string, in reflect.Value) {
implicit := tag == ""
style := BLOCK_SEQUENCE_STYLE
if r.flow {
r.flow = false
style = FLOW_SEQUENCE_STYLE
}
r.emit(NewSequenceStartEvent(nil, []byte(tag), implicit, style))
n := in.Len()
for i := 0; i < n; i++ {
r.marshal("", in.Index(i))
}
r.emit(NewSequenceEndEvent())
}
// isBase60 returns whether s is in base 60 notation as defined in YAML 1.1.
//
// The base 60 float notation in YAML 1.1 is a terrible idea and is unsupported
// in YAML 1.2 and by this package, but these should be marshaled quoted for
// the time being for compatibility with other parsers.
func isBase60Float(s string) (result bool) {
// Fast path.
if s == "" {
return false
}
c := s[0]
if !(c == '+' || c == '-' || c >= '0' && c <= '9') || strings.IndexByte(s, ':') < 0 {
return false
}
// Do the full match.
return base60float.MatchString(s)
}
// From http://yaml.org/type/float.html, except the regular expression there
// is bogus. In practice parsers do not enforce the "\.[0-9_]*" suffix.
var base60float = regexp.MustCompile(`^[-+]?[0-9][0-9_]*(?::[0-5]?[0-9])+(?:\.[0-9_]*)?$`)
// isOldBool returns whether s is bool notation as defined in YAML 1.1.
//
// We continue to force strings that YAML 1.1 would interpret as booleans to be
// rendered as quotes strings so that the marshaled output valid for YAML 1.1
// parsing.
func isOldBool(s string) (result bool) {
switch s {
case "y", "Y", "yes", "Yes", "YES", "on", "On", "ON",
"n", "N", "no", "No", "NO", "off", "Off", "OFF":
return true
default:
return false
}
}
// looksLikeMerge returns true if the given string is the merge indicator "<<".
//
// When encoding a scalar with this exact value, it must be quoted to prevent it
// from being interpreted as a merge indicator during decoding.
func looksLikeMerge(s string) (result bool) {
return s == "<<"
}
func (r *Representer) stringv(tag string, in reflect.Value) {
var style ScalarStyle
s := in.String()
canUsePlain := true
switch {
case !utf8.ValidString(s):
if tag == binaryTag {
failf("explicitly tagged !!binary data must be base64-encoded")
}
if tag != "" {
failf("cannot marshal invalid UTF-8 data as %s", shortTag(tag))
}
// It can't be represented directly as YAML so use a binary tag
// and represent it as base64.
tag = binaryTag
s = encodeBase64(s)
case tag == "":
// Check to see if it would resolve to a specific
// tag when represented unquoted. If it doesn't,
// there's no need to quote it.
rtag, _ := resolve("", s)
canUsePlain = rtag == strTag &&
!(isBase60Float(s) ||
isOldBool(s) ||
looksLikeMerge(s))
}
// Note: it's possible for user code to emit invalid YAML
// if they explicitly specify a tag and a string containing
// text that's incompatible with that tag.
switch {
case strings.Contains(s, "\n"):
if r.flow || !shouldUseLiteralStyle(s) {
style = DOUBLE_QUOTED_SCALAR_STYLE
} else {
style = LITERAL_SCALAR_STYLE
}
case canUsePlain:
style = PLAIN_SCALAR_STYLE
default:
style = r.quotePreference.ScalarStyle()
}
r.emitScalar(s, "", tag, style, nil, nil, nil, nil)
}
func (r *Representer) boolv(tag string, in reflect.Value) {
var s string
if in.Bool() {
s = "true"
} else {
s = "false"
}
r.emitScalar(s, "", tag, PLAIN_SCALAR_STYLE, nil, nil, nil, nil)
}
func (r *Representer) intv(tag string, in reflect.Value) {
s := strconv.FormatInt(in.Int(), 10)
r.emitScalar(s, "", tag, PLAIN_SCALAR_STYLE, nil, nil, nil, nil)
}
func (r *Representer) uintv(tag string, in reflect.Value) {
s := strconv.FormatUint(in.Uint(), 10)
r.emitScalar(s, "", tag, PLAIN_SCALAR_STYLE, nil, nil, nil, nil)
}
func (r *Representer) timev(tag string, in reflect.Value) {
t := in.Interface().(time.Time)
s := t.Format(time.RFC3339Nano)
r.emitScalar(s, "", tag, PLAIN_SCALAR_STYLE, nil, nil, nil, nil)
}
func (r *Representer) floatv(tag string, in reflect.Value) {
// Issue #352: When formatting, use the precision of the underlying value
precision := 64
if in.Kind() == reflect.Float32 {
precision = 32
}
s := strconv.FormatFloat(in.Float(), 'g', -1, precision)
switch s {
case "+Inf":
s = ".inf"
case "-Inf":
s = "-.inf"
case "NaN":
s = ".nan"
}
r.emitScalar(s, "", tag, PLAIN_SCALAR_STYLE, nil, nil, nil, nil)
}
func (r *Representer) nilv() {
r.emitScalar("null", "", "", PLAIN_SCALAR_STYLE, nil, nil, nil, nil)
}
func (r *Representer) emitScalar(
value, anchor, tag string, style ScalarStyle, head, line, foot, tail []byte,
) {
// TODO Kill this function. Replace all initialize calls by their underlining Go literals.
implicit := tag == ""
if !implicit {
tag = longTag(tag)
}
event := NewScalarEvent([]byte(anchor), []byte(tag), []byte(value), implicit, implicit, style)
event.HeadComment = head
event.LineComment = line
event.FootComment = foot
event.TailComment = tail
r.emit(event)
}
func (r *Representer) nodev(in reflect.Value) {
r.node(in.Interface().(*Node), "")
}