switch to io.Writer

codec/v2/stablejson/duration.go

@@ -1,13 +1,13 @@
 package stablejson
 
 import (
-	"strings"
+	io "io"
 
 	"google.golang.org/protobuf/reflect/protoreflect"
 )
 
 const ()
 
-func marshalDuration(writer *strings.Builder, message protoreflect.Message) error {
+func marshalDuration(writer io.Writer, message protoreflect.Message) error {
 	return nil
 }

codec/v2/stablejson/fieldmask.go

@@ -2,6 +2,7 @@ package stablejson
 
 import (
 	"fmt"
+	io "io"
 	"strings"
 
 	"google.golang.org/protobuf/reflect/protoreflect"
@@ -11,7 +12,7 @@ const (
 	pathsName protoreflect.Name = "paths"
 )
 
-func marshalFieldMask(writer *strings.Builder, value protoreflect.Message) error {
+func marshalFieldMask(writer io.Writer, value protoreflect.Message) error {
 	field := value.Descriptor().Fields().ByName(pathsName)
 	if field == nil {
 		return fmt.Errorf("expected to find field %s", pathsName)

codec/v2/stablejson/float.go

@@ -1,23 +1,25 @@
 package stablejson
 
 import (
+	"io"
 	"math"
 	"strconv"
-	"strings"
 )
 
-func marshalFloat(writer *strings.Builder, x float64) {
+func marshalFloat(writer io.Writer, x float64) error {
 	// PROTO3 SPEC:
 	// JSON value will be a number or one of the special string values "NaN", "Infinity", and "-Infinity".
 	// Either numbers or strings are accepted. Exponent notation is also accepted.
 	// -0 is considered equivalent to 0.
+	var err error
 	if math.IsInf(x, -1) {
-		writer.WriteString("-Infinity")
+		_, err = writer.Write([]byte("-Infinity"))
 	} else if math.IsInf(x, 1) {
-		writer.WriteString("Infinity")
+		_, err = writer.Write([]byte("Infinity"))
 	} else if math.IsNaN(x) {
-		writer.WriteString("NaN")
+		_, err = writer.Write([]byte("NaN"))
 	} else {
-		writer.WriteString(strconv.FormatFloat(x, 'f', -1, 64))
+		_, err = writer.Write([]byte(strconv.FormatFloat(x, 'f', -1, 64)))
 	}
+	return err
 }

codec/v2/stablejson/marshal.go

@@ -1,8 +1,9 @@
 package stablejson
 
 import (
+	"bytes"
 	"fmt"
-	"strings"
+	"io"
 
 	"google.golang.org/protobuf/proto"
 	"google.golang.org/protobuf/reflect/protopath"
@@ -22,10 +23,15 @@ type MarshalOptions struct {
 }
 
 func (opts MarshalOptions) Marshal(message proto.Message) ([]byte, error) {
-	writer := &strings.Builder{}
+	buf := &bytes.Buffer{}
+	err := opts.MarshalTo(message, buf)
+	return buf.Bytes(), err
+}
+
+func (opts MarshalOptions) MarshalTo(message proto.Message, writer io.Writer) error {
 	firstStack := []bool{true}
 	skipNext := false
-	err := protorange.Options{
+	return protorange.Options{
 		Stable: true,
 	}.Range(message.ProtoReflect(),
 		// push
@@ -37,7 +43,10 @@ func (opts MarshalOptions) Marshal(message proto.Message) ([]byte, error) {
 
 			// Starting printing the value.
 			if !firstStack[len(firstStack)-1] {
-				writer.WriteString(",")
+				_, err := writer.Write([]byte(","))
+				if err != nil {
+					return err
+				}
 			}
 			firstStack[len(firstStack)-1] = false
 
@@ -48,21 +57,27 @@ func (opts MarshalOptions) Marshal(message proto.Message) ([]byte, error) {
 			switch last.Step.Kind() {
 			case protopath.FieldAccessStep:
 				fd = last.Step.FieldDescriptor()
-				_, _ = fmt.Fprintf(writer, "%q:", fd.Name())
+				_, err := fmt.Fprintf(writer, "%q:", fd.Name())
+				if err != nil {
+					return err
+				}
 
 			case protopath.ListIndexStep:
 				fd = beforeLast.Step.FieldDescriptor() // lists always appear in the context of a repeated field
 
 			case protopath.MapIndexStep:
 				fd = beforeLast.Step.FieldDescriptor() // maps always appear in the context of a repeated field
-				_, _ = fmt.Fprintf(writer, "%q:", last.Step.MapIndex().String())
+				_, err := fmt.Fprintf(writer, "%q:", last.Step.MapIndex().String())
+				if err != nil {
+					return err
+				}
 
 			case protopath.AnyExpandStep:
-				_, _ = fmt.Fprintf(writer, `"@type":%q`, last.Value.Message().Descriptor().FullName())
-				return nil
+				_, err := fmt.Fprintf(writer, `"@type":%q`, last.Value.Message().Descriptor().FullName())
+				return err
 
 			case protopath.UnknownAccessStep:
-				writer.WriteString("?:")
+				return fmt.Errorf("unexpected %s", protopath.UnknownAccessStep)
 			}
 
 			switch value := last.Value.Interface().(type) {
@@ -79,23 +94,36 @@ func (opts MarshalOptions) Marshal(message proto.Message) ([]byte, error) {
 
 				firstStack = append(firstStack, true)
 			case protoreflect.List:
-				writer.WriteString("[")
+				_, err := writer.Write([]byte("["))
+				if err != nil {
+					return err
+				}
 				firstStack = append(firstStack, true)
 			case protoreflect.Map:
-				_, _ = fmt.Fprintf(writer, "{")
+				_, err := fmt.Fprintf(writer, "{")
+				if err != nil {
+					return err
+				}
 				firstStack = append(firstStack, true)
 			case protoreflect.EnumNumber:
 				var ev protoreflect.EnumValueDescriptor
 				if fd != nil {
 					ev = fd.Enum().Values().ByNumber(value)
 				}
+				var err error
 				if ev != nil {
-					_, _ = fmt.Fprintf(writer, "%q", ev.Name())
+					_, err = fmt.Fprintf(writer, "%q", ev.Name())
 				} else {
-					_, _ = fmt.Fprintf(writer, "%v", value)
+					_, err = fmt.Fprintf(writer, "%v", value)
+				}
+				if err != nil {
+					return err
 				}
 			case string:
-				_, _ = fmt.Fprintf(writer, "%q", value)
+				_, err := fmt.Fprintf(writer, "%q", value)
+				if err != nil {
+					return err
+				}
 			default:
 				return opts.marshalScalar(writer, value)
 			}
@@ -119,5 +147,4 @@ func (opts MarshalOptions) Marshal(message proto.Message) ([]byte, error) {
 			return nil
 		},
 	)
-	return []byte(writer.String()), err
 }

codec/v2/stablejson/marshal_test.go

@@ -87,14 +87,17 @@ func TestStableJSON(t *testing.T) {
 		Uint32Value: &wrapperspb.UInt32Value{Value: 37492},
 		Uint64Value: &wrapperspb.UInt64Value{Value: 1892409137358391},
 		FieldMask:   &fieldmaskpb.FieldMask{Paths: []string{"a.b", "a.c", "b"}},
-		ListValue:   &structpb.ListValue{Values: nil},
-		Value:       &structpb.Value{},
-		NullValue:   structpb.NullValue_NULL_VALUE,
-		Empty:       &emptypb.Empty{},
+		ListValue: &structpb.ListValue{Values: []*structpb.Value{
+			structpb.NewNumberValue(1.1),
+			structpb.NewStringValue("qrs"),
+		}},
+		Value:     &structpb.Value{},
+		NullValue: structpb.NullValue_NULL_VALUE,
+		Empty:     &emptypb.Empty{},
 	}
 	bz, err := stablejson.Marshal(msg)
 	assert.NilError(t, err)
 	assert.Equal(t,
-		`{}`,
+		`{"message":{"foo":"test"},"enum":"ONE","str_map":{"bar":"def","foo":"abc"},"int32_map":{"-3":"xyz","0":"abc","10":"qrs"},"bool_map":{"false":"F","true":"T"},"repeated":[3,-7,2,6,4],"str":"abcxyz\"foo\"def","bool":true,"bytes":"AAECAw==","i32":-15,"f32":1001,"u32":1200,"si32":-376,"sf32":-1000,"i64":"14578294827584932","f64":"9572348124213523654","u64":"4759492485","si64":"-59268425823934","sf64":"-659101379604211154","float":1,"double":5235.2941,"any":{"@type":"testpb.ABitOfEverything","str":"abc","i32":10},"timestamp":},"duration":},"struct":{"bool":true,"nested struct":{"a":"abc"},"null":null,"num":3.76,"str":"abc","struct list":["xyz",false,-9]}}},"bool_value":true},"bytes_value":"AAECAw=="},"double_value":1.324},"float_value":-1},"int32_value":10},"int64_value":"-376923457"},"string_value":"gfedcba"},"uint32_value":37492},"uint64_value":"1892409137358391"},"field_mask":"a.b,a.c,b"]},"list_value":[1.1,"qrs"]]},"value":}}}`,
 		string(bz))
 }

codec/v2/stablejson/message.go

@@ -1,12 +1,12 @@
 package stablejson
 
 import (
-	"strings"
+	"io"
 
 	"google.golang.org/protobuf/reflect/protoreflect"
 )
 
-func (opts MarshalOptions) marshalMessage(writer *strings.Builder, value protoreflect.Message) (continueRange bool, error error) {
+func (opts MarshalOptions) marshalMessage(writer io.Writer, value protoreflect.Message) (continueRange bool, error error) {
 	switch value.Descriptor().FullName() {
 	case timestampFullName:
 		return false, marshalTimestamp(writer, value)
@@ -19,17 +19,17 @@ func (opts MarshalOptions) marshalMessage(writer *strings.Builder, value protore
 	case valueFullName:
 		return false, marshalValue(writer, value)
 	case nullValueFullName:
-		writer.WriteString("null")
-		return false, nil
+		_, err := writer.Write([]byte("null"))
+		return false, err
 	case boolValueFullName, int32ValueFullName, int64ValueFullName, uint32ValueFullName, uint64ValueFullName,
 		stringValueFullName, bytesValueFullName, floatValueFullName, doubleValueFullName:
 		return false, opts.marshalWrapper(writer, value)
 	case fieldMaskFullName:
 		return false, marshalFieldMask(writer, value)
 	}
 
-	writer.WriteString("{")
-	return true, nil
+	_, err := writer.Write([]byte("{"))
+	return true, err
 }
 
 const (

codec/v2/stablejson/scalar.go

@@ -3,21 +3,21 @@ package stablejson
 import (
 	"encoding/base64"
 	"fmt"
-	"strings"
+	"io"
 )
 
-func (opts MarshalOptions) marshalScalar(writer *strings.Builder, value interface{}) error {
+func (opts MarshalOptions) marshalScalar(writer io.Writer, value interface{}) error {
 	switch value := value.(type) {
 	case string:
 		_, _ = fmt.Fprintf(writer, "%q", value)
 	case []byte:
-		writer.WriteString(`"`)
+		_, _ = writer.Write([]byte(`"`))
 		if opts.HexBytes {
 			_, _ = fmt.Fprintf(writer, "%X", value)
 		} else {
-			writer.WriteString(base64.StdEncoding.EncodeToString(value))
+			_, _ = writer.Write([]byte(base64.StdEncoding.EncodeToString(value)))
 		}
-		writer.WriteString(`"`)
+		_, _ = writer.Write([]byte(`"`))
 	case bool:
 		_, _ = fmt.Fprintf(writer, "%t", value)
 	case int32:

codec/v2/stablejson/struct.go

@@ -2,9 +2,8 @@ package stablejson
 
 import (
 	"fmt"
+	io "io"
 	"sort"
-	"strconv"
-	"strings"
 
 	"golang.org/x/exp/maps"
 	"google.golang.org/protobuf/reflect/protoreflect"
@@ -22,11 +21,14 @@ const (
 	listValueField   protoreflect.Name = "list_value"
 )
 
-func marshalStruct(writer *strings.Builder, value protoreflect.Message) error {
+func marshalStruct(writer io.Writer, value protoreflect.Message) error {
 	field := value.Descriptor().Fields().ByName(fieldsField)
 	m1 := value.Get(field).Map()
 
-	writer.WriteString("{")
+	_, err := writer.Write([]byte("{"))
+	if err != nil {
+		return err
+	}
 
 	m2 := map[string]protoreflect.Message{}
 	m1.Range(func(key protoreflect.MapKey, value protoreflect.Value) bool {
@@ -39,7 +41,10 @@ func marshalStruct(writer *strings.Builder, value protoreflect.Message) error {
 	first := true
 	for _, k := range keys {
 		if !first {
-			writer.WriteString(",")
+			_, err := writer.Write([]byte(","))
+			if err != nil {
+				return err
+			}
 		}
 
 		first = false
@@ -51,20 +56,27 @@ func marshalStruct(writer *strings.Builder, value protoreflect.Message) error {
 		}
 	}
 
-	writer.WriteString("}")
-	return nil
+	_, err = writer.Write([]byte("}"))
+	return err
 }
 
-func marshalListValue(writer *strings.Builder, value protoreflect.Message) error {
+func marshalListValue(writer io.Writer, value protoreflect.Message) error {
 	field := value.Descriptor().Fields().ByName(valuesField)
 	list := value.Get(field).List()
 	n := list.Len()
 
-	writer.WriteString("[")
+	_, err := writer.Write([]byte("["))
+	if err != nil {
+		return err
+	}
+
 	first := true
 	for i := 0; i < n; i++ {
 		if !first {
-			writer.WriteString(",")
+			_, err = writer.Write([]byte(","))
+			if err != nil {
+				return err
+			}
 		}
 		first = false
 
@@ -73,32 +85,33 @@ func marshalListValue(writer *strings.Builder, value protoreflect.Message) error
 			return err
 		}
 	}
-	writer.WriteString("]")
 
-	return nil
+	_, err = writer.Write([]byte("]"))
+	return err
 }
 
-func marshalValue(writer *strings.Builder, value protoreflect.Message) error {
+func marshalValue(writer io.Writer, value protoreflect.Message) error {
 	field := value.WhichOneof(value.Descriptor().Oneofs().ByName(kindOneOf))
 	if field == nil {
 		return nil
 	}
 
+	var err error
 	switch field.Name() {
 	case nullValueField:
-		writer.WriteString("null")
+		_, err = writer.Write([]byte("null"))
 	case numberValueField:
-		marshalFloat(writer, value.Get(field).Float())
+		err = marshalFloat(writer, value.Get(field).Float())
 	case stringValueField:
-		_, _ = fmt.Fprintf(writer, "%q", value.Get(field).String())
+		_, err = fmt.Fprintf(writer, "%q", value.Get(field).String())
 	case boolValueField:
-		writer.WriteString(strconv.FormatBool(value.Get(field).Bool()))
+		_, err = fmt.Fprintf(writer, "%t", value.Get(field).Bool())
 	case structValueField:
 		return marshalStruct(writer, value.Get(field).Message())
 	case listValueField:
 		return marshalListValue(writer, value.Get(field).Message())
 	default:
 		return fmt.Errorf("unexpected field in google.protobuf.Value: %v", field)
 	}
-	return nil
+	return err
 }