use UnmarshalJSONFrom function

Signed-off-by: Tim Ramlot <42113979+inteon@users.noreply.github.com>

Author: inteon

fieldpath/serialize-pe.go

@@ -17,15 +17,12 @@ limitations under the License.
 package fieldpath
 
 import (
-	"bytes"
 	"errors"
 	"fmt"
-	"io"
 	"strconv"
 	"strings"
 
 	"github.com/go-json-experiment/json"
-	"github.com/go-json-experiment/json/jsontext"
 	"sigs.k8s.io/structured-merge-diff/v6/value"
 )
 
@@ -55,47 +52,6 @@ var (
 	peKeySepBytes   = []byte{peKey, peSeparator}
 )
 
-// FieldListFromJSON is a helper function for reading a JSON document.
-func fieldListFromJSON(input []byte) (value.FieldList, error) {
-	parser := jsontext.NewDecoder(bytes.NewBuffer(input))
-
-	if objStart, err := parser.ReadToken(); err != nil {
-		return nil, fmt.Errorf("parsing JSON: %v", err)
-	} else if objStart.Kind() != jsontext.BeginObject.Kind() {
-		return nil, fmt.Errorf("expected object")
-	}
-
-	var fields value.FieldList
-	for {
-		if parser.PeekKind() == jsontext.EndObject.Kind() {
-			if _, err := parser.ReadToken(); err != nil {
-				return nil, fmt.Errorf("parsing JSON: %v", err)
-			}
-			break
-		}
-
-		rawKey, err := parser.ReadToken()
-		if err == io.EOF {
-			return nil, fmt.Errorf("unexpected EOF")
-		} else if err != nil {
-			return nil, fmt.Errorf("parsing JSON: %v", err)
-		}
-
-		k := rawKey.String()
-
-		var v any
-		if err := json.UnmarshalDecode(parser, &v); err == io.EOF {
-			return nil, fmt.Errorf("unexpected EOF")
-		} else if err != nil {
-			return nil, fmt.Errorf("parsing JSON: %v", err)
-		}
-
-		fields = append(fields, value.Field{Name: k, Value: value.NewValueInterface(v)})
-	}
-
-	return fields, nil
-}
-
 // DeserializePathElement parses a serialized path element
 func DeserializePathElement(s string) (PathElement, error) {
 	b := []byte(s)
@@ -121,11 +77,10 @@ func DeserializePathElement(s string) (PathElement, error) {
 		}
 		return PathElement{Value: &v}, nil
 	case peKeySepBytes[0]:
-		fields, err := fieldListFromJSON(b)
-		if err != nil {
+		var fields value.FieldList
+		if err := json.Unmarshal(b, &fields); err != nil {
 			return PathElement{}, err
 		}
-		fields.Sort()
 		return PathElement{Key: &fields}, nil
 	case peIndexSepBytes[0]:
 		i, err := strconv.Atoi(s[2:])

fieldpath/serialize.go

@@ -128,24 +128,21 @@ func (s *setContentsV1) emitContentsV1(includeSelf bool, om *jsontext.Encoder) e
 	return nil
 }
 
-// FromJSON clears s and reads a JSON formatted set structure.
-func (s *Set) FromJSON(r io.Reader) error {
-	parser := jsontext.NewDecoder(r)
-
-	found, _, err := readIterV1(parser)
+func (s *setContentsV1) UnmarshalJSONFrom(dec *jsontext.Decoder) error {
+	found, _, err := s.readIterV1(dec)
 	if err != nil {
 		return err
 	} else if found == nil {
-		*s = Set{}
+		*(*Set)(s) = Set{}
 	} else {
-		*s = *found
+		*(*Set)(s) = *found
 	}
 	return nil
 }
 
 // returns true if this subtree is also (or only) a member of parent; s is nil
 // if there are no further children.
-func readIterV1(parser *jsontext.Decoder) (children *Set, isMember bool, err error) {
+func (s *setContentsV1) readIterV1(parser *jsontext.Decoder) (children *Set, isMember bool, err error) {
 	if objStart, err := parser.ReadToken(); err != nil {
 		return nil, false, fmt.Errorf("parsing JSON: %v", err)
 	} else if objStart.Kind() != jsontext.BeginObject.Kind() {
@@ -188,7 +185,7 @@ func readIterV1(parser *jsontext.Decoder) (children *Set, isMember bool, err err
 			return nil, false, fmt.Errorf("parsing key as path element: %v", err)
 		}
 
-		grandChildren, isChildMember, err := readIterV1(parser)
+		grandChildren, isChildMember, err := s.readIterV1(parser)
 		if err != nil {
 			return nil, false, fmt.Errorf("parsing value as set: %v", err)
 		}
@@ -226,3 +223,8 @@ func readIterV1(parser *jsontext.Decoder) (children *Set, isMember bool, err err
 
 	return children, isMember, nil
 }
+
+// FromJSON clears s and reads a JSON formatted set structure.
+func (s *Set) FromJSON(r io.Reader) error {
+	return json.UnmarshalRead(r, (*setContentsV1)(s))
+}

value/fields.go

@@ -17,6 +17,8 @@ limitations under the License.
 package value
 
 import (
+	"fmt"
+	"io"
 	"sort"
 	"strings"
 
@@ -34,9 +36,9 @@ type Field struct {
 // have a different name.
 type FieldList []Field
 
-func (fl FieldList) MarshalJSONTo(enc *jsontext.Encoder) error {
+func (fl *FieldList) MarshalJSONTo(enc *jsontext.Encoder) error {
 	enc.WriteToken(jsontext.BeginObject)
-	for _, f := range fl {
+	for _, f := range *fl {
 		if err := enc.WriteToken(jsontext.String(f.Name)); err != nil {
 			return err
 		}
@@ -49,6 +51,48 @@ func (fl FieldList) MarshalJSONTo(enc *jsontext.Encoder) error {
 	return nil
 }
 
+// FieldListFromJSON is a helper function for reading a JSON document.
+func (fl *FieldList) UnmarshalJSONFrom(parser *jsontext.Decoder) error {
+	if objStart, err := parser.ReadToken(); err != nil {
+		return fmt.Errorf("parsing JSON: %v", err)
+	} else if objStart.Kind() != jsontext.BeginObject.Kind() {
+		return fmt.Errorf("expected object")
+	}
+
+	var fields FieldList
+	for {
+		if parser.PeekKind() == jsontext.EndObject.Kind() {
+			if _, err := parser.ReadToken(); err != nil {
+				return fmt.Errorf("parsing JSON: %v", err)
+			}
+			break
+		}
+
+		rawKey, err := parser.ReadToken()
+		if err == io.EOF {
+			return fmt.Errorf("unexpected EOF")
+		} else if err != nil {
+			return fmt.Errorf("parsing JSON: %v", err)
+		}
+
+		k := rawKey.String()
+
+		var v any
+		if err := json.UnmarshalDecode(parser, &v); err == io.EOF {
+			return fmt.Errorf("unexpected EOF")
+		} else if err != nil {
+			return fmt.Errorf("parsing JSON: %v", err)
+		}
+
+		fields = append(fields, Field{Name: k, Value: NewValueInterface(v)})
+	}
+
+	fields.Sort()
+	*fl = fields
+
+	return nil
+}
+
 // Copy returns a copy of the FieldList.
 // Values are not copied.
 func (f FieldList) Copy() FieldList {