Deserialize JSON NaN, Infinity and -Infinity to corresponding Go values (#363)

Deserialize JSON NaN, Infinity and -Infinity to corresponding Go values

jsonpb/jsonpb.go

@@ -108,6 +108,12 @@ func (m *Marshaler) MarshalToString(pb proto.Message) (string, error) {
 
 type int32Slice []int32
 
+var nonFinite = map[string]float64{
+	`"NaN"`:       math.NaN(),
+	`"Infinity"`:  math.Inf(1),
+	`"-Infinity"`: math.Inf(-1),
+}
+
 // For sorting extensions ids to ensure stable output.
 func (s int32Slice) Len() int           { return len(s) }
 func (s int32Slice) Less(i, j int) bool { return s[i] < s[j] }
@@ -981,6 +987,15 @@ func (u *Unmarshaler) unmarshalValue(target reflect.Value, inputValue json.RawMe
 		inputValue = inputValue[1 : len(inputValue)-1]
 	}
 
+	// Non-finite numbers can be encoded as strings.
+	isFloat := targetType.Kind() == reflect.Float32 || targetType.Kind() == reflect.Float64
+	if isFloat {
+		if num, ok := nonFinite[string(inputValue)]; ok {
+			target.SetFloat(num)
+			return nil
+		}
+	}
+
 	// Use the encoding/json for parsing other value types.
 	return json.Unmarshal(inputValue, target.Addr().Interface())
 }

jsonpb/jsonpb_test.go

@@ -530,6 +530,9 @@ var unmarshalingTests = []struct {
 		}}},
 	{"unquoted int64 object", Unmarshaler{}, `{"oInt64":-314}`, &pb.Simple{OInt64: proto.Int64(-314)}},
 	{"unquoted uint64 object", Unmarshaler{}, `{"oUint64":123}`, &pb.Simple{OUint64: proto.Uint64(123)}},
+	{"NaN", Unmarshaler{}, `{"oDouble":"NaN"}`, &pb.Simple{ODouble: proto.Float64(math.NaN())}},
+	{"Inf", Unmarshaler{}, `{"oFloat":"Infinity"}`, &pb.Simple{OFloat: proto.Float32(float32(math.Inf(1)))}},
+	{"-Inf", Unmarshaler{}, `{"oDouble":"-Infinity"}`, &pb.Simple{ODouble: proto.Float64(math.Inf(-1))}},
 	{"map<int64, int32>", Unmarshaler{}, `{"nummy":{"1":2,"3":4}}`, &pb.Mappy{Nummy: map[int64]int32{1: 2, 3: 4}}},
 	{"map<string, string>", Unmarshaler{}, `{"strry":{"\"one\"":"two","three":"four"}}`, &pb.Mappy{Strry: map[string]string{`"one"`: "two", "three": "four"}}},
 	{"map<int32, Object>", Unmarshaler{}, `{"objjy":{"1":{"dub":1}}}`, &pb.Mappy{Objjy: map[int32]*pb.Simple3{1: &pb.Simple3{Dub: 1}}}},