marshal opts

decode.go

@@ -876,7 +876,7 @@ func isStringMap(n *Node) bool {
 }
 
 func (d *decoder) mappingStruct(n *Node, out reflect.Value) (good bool) {
-	sinfo, err := getStructInfo(out.Type())
+	sinfo, err := getStructInfo(out.Type(), false)
 	if err != nil {
 		panic(err)
 	}

encode.go

@@ -29,24 +29,37 @@ import (
 )
 
 type encoder struct {
-	emitter  yaml_emitter_t
-	event    yaml_event_t
-	out      []byte
-	flow     bool
-	indent   int
-	doneInit bool
+	emitter      yaml_emitter_t
+	event        yaml_event_t
+	out          []byte
+	flow         bool
+	indent       int
+	doneInit     bool
+	originalCase bool
+	arg          any
 }
 
-func newEncoder() *encoder {
-	e := &encoder{}
+func newEncoder_(arg any, opts ...MarshalOpt) (e *encoder) {
+	e = &encoder{}
+	e.arg = arg
+	for _, o := range opts {
+		if o == OriginalCase {
+			e.originalCase = true
+		}
+	}
+	return
+}
+
+func newEncoder(arg any, opts ...MarshalOpt) *encoder {
+	e := newEncoder_(arg, opts...)
 	yaml_emitter_initialize(&e.emitter)
 	yaml_emitter_set_output_string(&e.emitter, &e.out)
 	yaml_emitter_set_unicode(&e.emitter, true)
 	return e
 }
 
-func newEncoderWithWriter(w io.Writer) *encoder {
-	e := &encoder{}
+func newEncoderWithWriter(w io.Writer, arg any, opts ...MarshalOpt) *encoder {
+	e := newEncoder_(arg, opts...)
 	yaml_emitter_initialize(&e.emitter)
 	yaml_emitter_set_output_writer(&e.emitter, w)
 	yaml_emitter_set_unicode(&e.emitter, true)
@@ -137,7 +150,7 @@ func (e *encoder) marshal(tag string, in reflect.Value) {
 		e.stringv(tag, reflect.ValueOf(value.String()))
 		return
 	case Marshaler:
-		v, err := value.MarshalYAML()
+		v, err := value.MarshalYAML(e.arg)
 		if err != nil {
 			fail(err)
 		}
@@ -212,7 +225,7 @@ func (e *encoder) fieldByIndex(v reflect.Value, index []int) (field reflect.Valu
 }
 
 func (e *encoder) structv(tag string, in reflect.Value) {
-	sinfo, err := getStructInfo(in.Type())
+	sinfo, err := getStructInfo(in.Type(), e.originalCase)
 	if err != nil {
 		panic(err)
 	}

go.mod

@@ -1,5 +1,5 @@
-module "gopkg.in/yaml.v3"
+module gopkg.in/yaml.v3
 
-require (
-	"gopkg.in/check.v1" v0.0.0-20161208181325-20d25e280405
-)
+go 1.19
+
+require gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405

yaml.go

@@ -17,8 +17,7 @@
 //
 // Source code and other details for the project are available at GitHub:
 //
-//   https://github.com/go-yaml/yaml
-//
+//	https://github.com/go-yaml/yaml
 package yaml
 
 import (
@@ -48,7 +47,7 @@ type obsoleteUnmarshaler interface {
 // If an error is returned by MarshalYAML, the marshaling procedure stops
 // and returns with the provided error.
 type Marshaler interface {
-	MarshalYAML() (interface{}, error)
+	MarshalYAML(arg any) (interface{}, error)
 }
 
 // Unmarshal decodes the first document found within the in byte slice
@@ -75,16 +74,15 @@ type Marshaler interface {
 //
 // For example:
 //
-//     type T struct {
-//         F int `yaml:"a,omitempty"`
-//         B int
-//     }
-//     var t T
-//     yaml.Unmarshal([]byte("a: 1\nb: 2"), &t)
+//	type T struct {
+//	    F int `yaml:"a,omitempty"`
+//	    B int
+//	}
+//	var t T
+//	yaml.Unmarshal([]byte("a: 1\nb: 2"), &t)
 //
 // See the documentation of Marshal for the format of tags and a list of
 // supported tag options.
-//
 func Unmarshal(in []byte, out interface{}) (err error) {
 	return unmarshal(in, out, false)
 }
@@ -185,46 +183,55 @@ func unmarshal(in []byte, out interface{}, strict bool) (err error) {
 //
 // The field tag format accepted is:
 //
-//     `(...) yaml:"[<key>][,<flag1>[,<flag2>]]" (...)`
+//	`(...) yaml:"[<key>][,<flag1>[,<flag2>]]" (...)`
 //
 // The following flags are currently supported:
 //
-//     omitempty    Only include the field if it's not set to the zero
-//                  value for the type or to empty slices or maps.
-//                  Zero valued structs will be omitted if all their public
-//                  fields are zero, unless they implement an IsZero
-//                  method (see the IsZeroer interface type), in which
-//                  case the field will be excluded if IsZero returns true.
+//	omitempty    Only include the field if it's not set to the zero
+//	             value for the type or to empty slices or maps.
+//	             Zero valued structs will be omitted if all their public
+//	             fields are zero, unless they implement an IsZero
+//	             method (see the IsZeroer interface type), in which
+//	             case the field will be excluded if IsZero returns true.
 //
-//     flow         Marshal using a flow style (useful for structs,
-//                  sequences and maps).
+//	flow         Marshal using a flow style (useful for structs,
+//	             sequences and maps).
 //
-//     inline       Inline the field, which must be a struct or a map,
-//                  causing all of its fields or keys to be processed as if
-//                  they were part of the outer struct. For maps, keys must
-//                  not conflict with the yaml keys of other struct fields.
+//	inline       Inline the field, which must be a struct or a map,
+//	             causing all of its fields or keys to be processed as if
+//	             they were part of the outer struct. For maps, keys must
+//	             not conflict with the yaml keys of other struct fields.
 //
 // In addition, if the key is "-", the field is ignored.
 //
 // For example:
 //
-//     type T struct {
-//         F int `yaml:"a,omitempty"`
-//         B int
-//     }
-//     yaml.Marshal(&T{B: 2}) // Returns "b: 2\n"
-//     yaml.Marshal(&T{F: 1}} // Returns "a: 1\nb: 0\n"
-//
+//	type T struct {
+//	    F int `yaml:"a,omitempty"`
+//	    B int
+//	}
+//	yaml.Marshal(&T{B: 2}) // Returns "b: 2\n"
+//	yaml.Marshal(&T{F: 1}} // Returns "a: 1\nb: 0\n"
 func Marshal(in interface{}) (out []byte, err error) {
+	return MarshalWithOpts(in, nil)
+}
+
+func MarshalWithOpts(in interface{}, arg any, opts ...MarshalOpt) (out []byte, err error) {
 	defer handleErr(&err)
-	e := newEncoder()
+	e := newEncoder(arg, opts...)
 	defer e.destroy()
 	e.marshalDoc("", reflect.ValueOf(in))
 	e.finish()
 	out = e.out
 	return
 }
 
+type MarshalOpt int
+
+const (
+	OriginalCase MarshalOpt = 1
+)
+
 // An Encoder writes YAML values to an output stream.
 type Encoder struct {
 	encoder *encoder
@@ -234,8 +241,12 @@ type Encoder struct {
 // The Encoder should be closed after use to flush all data
 // to w.
 func NewEncoder(w io.Writer) *Encoder {
+	return NewEncoderWithOpts(w, nil)
+}
+
+func NewEncoderWithOpts(w io.Writer, arg any, opts ...MarshalOpt) *Encoder {
 	return &Encoder{
-		encoder: newEncoderWithWriter(w),
+		encoder: newEncoderWithWriter(w, arg, opts...),
 	}
 }
 
@@ -257,8 +268,12 @@ func (e *Encoder) Encode(v interface{}) (err error) {
 // See the documentation for Marshal for details about the
 // conversion of Go values into YAML.
 func (n *Node) Encode(v interface{}) (err error) {
+	return n.EncodeWithOpts(v, nil)
+}
+
+func (n *Node) EncodeWithOpts(v interface{}, arg any, opts ...MarshalOpt) (err error) {
 	defer handleErr(&err)
-	e := newEncoder()
+	e := newEncoder(arg, opts...)
 	defer e.destroy()
 	e.marshalDoc("", reflect.ValueOf(v))
 	e.finish()
@@ -358,22 +373,21 @@ const (
 //
 // For example:
 //
-//     var person struct {
-//             Name    string
-//             Address yaml.Node
-//     }
-//     err := yaml.Unmarshal(data, &person)
-// 
-// Or by itself:
+//	var person struct {
+//	        Name    string
+//	        Address yaml.Node
+//	}
+//	err := yaml.Unmarshal(data, &person)
 //
-//     var person Node
-//     err := yaml.Unmarshal(data, &person)
+// Or by itself:
 //
+//	var person Node
+//	err := yaml.Unmarshal(data, &person)
 type Node struct {
 	// Kind defines whether the node is a document, a mapping, a sequence,
 	// a scalar value, or an alias to another node. The specific data type of
 	// scalar nodes may be obtained via the ShortTag and LongTag methods.
-	Kind  Kind
+	Kind Kind
 
 	// Style allows customizing the apperance of the node in the tree.
 	Style Style
@@ -421,7 +435,6 @@ func (n *Node) IsZero() bool {
 		n.HeadComment == "" && n.LineComment == "" && n.FootComment == "" && n.Line == 0 && n.Column == 0
 }
 
-
 // LongTag returns the long form of the tag that indicates the data type for
 // the node. If the Tag field isn't explicitly defined, one will be computed
 // based on the node properties.
@@ -524,7 +537,7 @@ func init() {
 	unmarshalerType = reflect.ValueOf(&v).Elem().Type()
 }
 
-func getStructInfo(st reflect.Type) (*structInfo, error) {
+func getStructInfo(st reflect.Type, originalCase bool) (*structInfo, error) {
 	fieldMapMutex.RLock()
 	sinfo, found := structMap[st]
 	fieldMapMutex.RUnlock()
@@ -592,7 +605,7 @@ func getStructInfo(st reflect.Type) (*structInfo, error) {
 				if reflect.PtrTo(ftype).Implements(unmarshalerType) {
 					inlineUnmarshalers = append(inlineUnmarshalers, []int{i})
 				} else {
-					sinfo, err := getStructInfo(ftype)
+					sinfo, err := getStructInfo(ftype, originalCase)
 					if err != nil {
 						return nil, err
 					}
@@ -623,7 +636,11 @@ func getStructInfo(st reflect.Type) (*structInfo, error) {
 		if tag != "" {
 			info.Key = tag
 		} else {
-			info.Key = strings.ToLower(field.Name)
+			if originalCase {
+				info.Key = field.Name
+			} else {
+				info.Key = strings.ToLower(field.Name)
+			}
 		}
 
 		if _, found = fieldsMap[info.Key]; found {