Migrate to encoding/json/v2

fieldpath/path.go

@@ -80,7 +80,7 @@ func (fp Path) Copy() Path {
 
 // MakePath constructs a Path. The parts may be PathElements, ints, strings.
 func MakePath(parts ...interface{}) (Path, error) {
-	var fp Path
+	fp := make(Path, 0, len(parts))
 	for _, p := range parts {
 		switch t := p.(type) {
 		case PathElement:

fieldpath/serialize-pe.go

@@ -17,72 +17,101 @@ limitations under the License.
 package fieldpath
 
 import (
+	"bytes"
 	"errors"
 	"fmt"
 	"io"
 	"strconv"
 	"strings"
 
-	jsoniter "github.com/json-iterator/go"
+	"github.com/go-json-experiment/json"
+	"github.com/go-json-experiment/json/jsontext"
 	"sigs.k8s.io/structured-merge-diff/v6/value"
 )
 
 var ErrUnknownPathElementType = errors.New("unknown path element type")
 
 const (
 	// Field indicates that the content of this path element is a field's name
-	peField = "f"
+	peField byte = 'f'
 
 	// Value indicates that the content of this path element is a field's value
-	peValue = "v"
+	peValue byte = 'v'
 
 	// Index indicates that the content of this path element is an index in an array
-	peIndex = "i"
+	peIndex byte = 'i'
 
 	// Key indicates that the content of this path element is a key value map
-	peKey = "k"
+	peKey byte = 'k'
 
 	// Separator separates the type of a path element from the contents
-	peSeparator = ":"
+	peSeparator byte = ':'
 )
 
 var (
-	peFieldSepBytes = []byte(peField + peSeparator)
-	peValueSepBytes = []byte(peValue + peSeparator)
-	peIndexSepBytes = []byte(peIndex + peSeparator)
-	peKeySepBytes   = []byte(peKey + peSeparator)
-	peSepBytes      = []byte(peSeparator)
+	peFieldSepBytes = []byte{peField, peSeparator}
+	peValueSepBytes = []byte{peValue, peSeparator}
+	peIndexSepBytes = []byte{peIndex, peSeparator}
+	peKeySepBytes   = []byte{peKey, peSeparator}
 )
 
-// readJSONIter reads a Value from a JSON iterator.
-// DO NOT EXPORT
-// TODO: eliminate this https://github.com/kubernetes-sigs/structured-merge-diff/issues/202
-func readJSONIter(iter *jsoniter.Iterator) (value.Value, error) {
-	v := iter.Read()
-	if iter.Error != nil && iter.Error != io.EOF {
-		return nil, iter.Error
-	}
-	return value.NewValueInterface(v), nil
+// writeValueToEncoder writes a value to an Encoder.
+func writeValueToEncoder(v value.Value, enc *jsontext.Encoder) error {
+	return json.MarshalEncode(enc, v.Unstructured(), json.Deterministic(true))
 }
 
-// writeJSONStream writes a value into a JSON stream.
-// DO NOT EXPORT
-// TODO: eliminate this https://github.com/kubernetes-sigs/structured-merge-diff/issues/202
-func writeJSONStream(v value.Value, stream *jsoniter.Stream) {
-	stream.WriteVal(v.Unstructured())
+// 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)
 	if len(b) < 2 {
-		return PathElement{}, errors.New("key must be 2 characters long:")
+		return PathElement{}, errors.New("key must be 2 characters long")
 	}
-	typeSep, b := b[:2], b[2:]
-	if typeSep[1] != peSepBytes[0] {
+	typeSep0, typeSep1, b := b[0], b[1], b[2:]
+	if typeSep1 != peSeparator {
 		return PathElement{}, fmt.Errorf("missing colon: %v", s)
 	}
-	switch typeSep[0] {
+	switch typeSep0 {
 	case peFieldSepBytes[0]:
 		// Slice s rather than convert b, to save on
 		// allocations.
@@ -91,29 +120,18 @@ func DeserializePathElement(s string) (PathElement, error) {
 			FieldName: &str,
 		}, nil
 	case peValueSepBytes[0]:
-		iter := readPool.BorrowIterator(b)
-		defer readPool.ReturnIterator(iter)
-		v, err := readJSONIter(iter)
+		v, err := value.FromJSON(b)
 		if err != nil {
 			return PathElement{}, err
 		}
 		return PathElement{Value: &v}, nil
 	case peKeySepBytes[0]:
-		iter := readPool.BorrowIterator(b)
-		defer readPool.ReturnIterator(iter)
-		fields := value.FieldList{}
-
-		iter.ReadObjectCB(func(iter *jsoniter.Iterator, key string) bool {
-			v, err := readJSONIter(iter)
-			if err != nil {
-				iter.Error = err
-				return false
-			}
-			fields = append(fields, value.Field{Name: key, Value: v})
-			return true
-		})
+		fields, err := fieldListFromJSON(b)
+		if err != nil {
+			return PathElement{}, err
+		}
 		fields.Sort()
-		return PathElement{Key: &fields}, iter.Error
+		return PathElement{Key: &fields}, nil
 	case peIndexSepBytes[0]:
 		i, err := strconv.Atoi(s[2:])
 		if err != nil {
@@ -127,60 +145,58 @@ func DeserializePathElement(s string) (PathElement, error) {
 	}
 }
 
-var (
-	readPool  = jsoniter.NewIterator(jsoniter.ConfigCompatibleWithStandardLibrary).Pool()
-	writePool = jsoniter.NewStream(jsoniter.ConfigCompatibleWithStandardLibrary, nil, 1024).Pool()
-)
+type PathElementSerializer struct {
+	buffer  bytes.Buffer
+	encoder jsontext.Encoder
+}
 
 // SerializePathElement serializes a path element
 func SerializePathElement(pe PathElement) (string, error) {
-	buf := strings.Builder{}
-	err := serializePathElementToWriter(&buf, pe)
-	return buf.String(), err
+	byteVal, err := (&PathElementSerializer{}).serialize(pe)
+	return string(byteVal), err
 }
 
-func serializePathElementToWriter(w io.Writer, pe PathElement) error {
-	stream := writePool.BorrowStream(w)
-	defer writePool.ReturnStream(stream)
+func (pes *PathElementSerializer) serialize(pe PathElement) (string, error) {
+	pes.buffer.Reset()
+
 	switch {
 	case pe.FieldName != nil:
-		if _, err := stream.Write(peFieldSepBytes); err != nil {
-			return err
+		if _, err := pes.buffer.Write(peFieldSepBytes); err != nil {
+			return "", err
 		}
-		stream.WriteRaw(*pe.FieldName)
+		pes.buffer.WriteString(*pe.FieldName)
 	case pe.Key != nil:
-		if _, err := stream.Write(peKeySepBytes); err != nil {
-			return err
+		if _, err := pes.buffer.Write(peKeySepBytes); err != nil {
+			return "", err
 		}
-		stream.WriteObjectStart()
-
-		for i, field := range *pe.Key {
-			if i > 0 {
-				stream.WriteMore()
+		pes.encoder.Reset(&pes.buffer)
+		pes.encoder.WriteToken(jsontext.BeginObject)
+		for _, f := range *pe.Key {
+			if err := pes.encoder.WriteToken(jsontext.String(f.Name)); err != nil {
+				return "", err
+			}
+			if err := writeValueToEncoder(f.Value, &pes.encoder); err != nil {
+				return "", err
 			}
-			stream.WriteObjectField(field.Name)
-			writeJSONStream(field.Value, stream)
 		}
-		stream.WriteObjectEnd()
+		pes.encoder.WriteToken(jsontext.EndObject)
 	case pe.Value != nil:
-		if _, err := stream.Write(peValueSepBytes); err != nil {
-			return err
+		if _, err := pes.buffer.Write(peValueSepBytes); err != nil {
+			return "", err
+		}
+		pes.encoder.Reset(&pes.buffer)
+		if err := writeValueToEncoder(*pe.Value, &pes.encoder); err != nil {
+			return "", err
 		}
-		writeJSONStream(*pe.Value, stream)
 	case pe.Index != nil:
-		if _, err := stream.Write(peIndexSepBytes); err != nil {
-			return err
+		if _, err := pes.buffer.Write(peIndexSepBytes); err != nil {
+			return "", err
 		}
-		stream.WriteInt(*pe.Index)
+		pes.buffer.WriteString(strconv.Itoa(*pe.Index))
 	default:
-		return errors.New("invalid PathElement")
+		return "", errors.New("invalid PathElement")
 	}
-	b := stream.Buffer()
-	err := stream.Flush()
-	// Help jsoniter manage its buffers--without this, the next
-	// use of the stream is likely to require an allocation. Look
-	// at the jsoniter stream code to understand why. They were probably
-	// optimizing for folks using the buffer directly.
-	stream.SetBuffer(b[:0])
-	return err
+
+	// TODO: is there a way to not emit newlines
+	return strings.TrimSpace(pes.buffer.String()), nil
 }