decodeConfig

2 files changed, 38 insertions, 17 deletions

diff --git a/lib/lowmemjson/adapter_test.go b/lib/lowmemjson/adapter_test.go
index ffdc2ee..954381a 100644
--- a/lib/lowmemjson/adapter_test.go
+++ b/lib/lowmemjson/adapter_test.go
@@ -73,6 +73,7 @@ func Unmarshal(data []byte, ptr any) error {
 
 type _Decoder struct {
 	src *bufio.Reader
+	cfg decodeConfig
 }
 
 func NewDecoder(r io.Reader) *_Decoder {
@@ -81,8 +82,8 @@ func NewDecoder(r io.Reader) *_Decoder {
 	}
 }
 
-func (dec *_Decoder) DisallowUnknownFields() {}
-func (dec *_Decoder) UseNumber()             {}
+func (dec *_Decoder) DisallowUnknownFields() { dec.cfg.disallowUnknownFields = true }
+func (dec *_Decoder) UseNumber()             { dec.cfg.useNumber = true }
 
 func (dec *_Decoder) Buffered() io.Reader {
 	dat, _ := dec.src.Peek(dec.src.Buffered())
@@ -90,7 +91,7 @@ func (dec *_Decoder) Buffered() io.Reader {
 }
 
 func (dec *_Decoder) Decode(v any) error {
-	return Decode(dec.src, v)
+	return _Decode(dec.src, v, dec.cfg)
 }
 func (dec *_Decoder) InputOffset() int64 { return 0 }
 func (dec *_Decoder) More() bool {
diff --git a/lib/lowmemjson/decode.go b/lib/lowmemjson/decode.go
index 1604e87..c2e7ab1 100644
--- a/lib/lowmemjson/decode.go
+++ b/lib/lowmemjson/decode.go
@@ -75,7 +75,16 @@ func expectRune(r io.RuneReader, exp rune) {
 	}
 }
 
+type decodeConfig struct {
+	disallowUnknownFields bool
+	useNumber             bool
+}
+
 func Decode(r io.RuneScanner, ptr any) (err error) {
+	return _Decode(r, ptr, decodeConfig{})
+}
+
+func _Decode(r io.RuneScanner, ptr any, cfg decodeConfig) (err error) {
 	ptrVal := reflect.ValueOf(ptr)
 	if ptrVal.Kind() != reflect.Pointer || ptrVal.IsNil() || !ptrVal.Elem().CanSet() {
 		return &json.InvalidUnmarshalError{
@@ -93,7 +102,7 @@ func Decode(r io.RuneScanner, ptr any) (err error) {
 		}
 	}()
 	decodeWS(r)
-	decode(r, ptrVal.Elem())
+	decode(r, ptrVal.Elem(), cfg)
 	return nil
 }
 
@@ -124,7 +133,7 @@ var kind2bits = map[reflect.Kind]int{
 	reflect.Float64: 64,
 }
 
-func decode(r io.RuneScanner, val reflect.Value) {
+func decode(r io.RuneScanner, val reflect.Value, cfg decodeConfig) {
 	typ := val.Type()
 	switch {
 	case val.CanAddr() && reflect.PointerTo(typ) == rawMessagePtrType:
@@ -193,14 +202,14 @@ func decode(r io.RuneScanner, val reflect.Value) {
 		case reflect.Interface:
 			if val.IsNil() {
 				if typ == anyType {
-					val.Set(reflect.ValueOf(decodeAny(r)))
+					val.Set(reflect.ValueOf(decodeAny(r, cfg)))
 				} else {
 					panic(decodeError{&json.UnsupportedTypeError{
 						Type: typ,
 					}})
 				}
 			} else {
-				decode(r, val.Elem())
+				decode(r, val.Elem(), cfg)
 			}
 		case reflect.Struct:
 			index := indexStruct(typ)
@@ -209,6 +218,9 @@ func decode(r io.RuneScanner, val reflect.Value) {
 				name := nameBuf.String()
 				idx, ok := index.byName[name]
 				if !ok {
+					if cfg.disallowUnknownFields {
+						panic(decodeError{fmt.Errorf("unknown field %q", name)})
+					}
 					scan(r, io.Discard)
 					return
 				}
@@ -239,12 +251,12 @@ func decode(r io.RuneScanner, val reflect.Value) {
 						}
 					case '"':
 						decodeString(r, &buf)
-						decode(&buf, fVal)
+						decode(&buf, fVal, cfg)
 					default:
 						panic(decodeError{fmt.Errorf("invalid character %q for ,string struct value", peekRune(r))})
 					}
 				} else {
-					decode(r, fVal)
+					decode(r, fVal, cfg)
 				}
 			})
 		case reflect.Map:
@@ -288,7 +300,7 @@ func decode(r io.RuneScanner, val reflect.Value) {
 					}
 
 					fValPtr := reflect.New(typ.Elem())
-					decode(r, fValPtr.Elem())
+					decode(r, fValPtr.Elem(), cfg)
 
 					val.SetMapIndex(nameValPtr.Elem(), fValPtr.Elem())
 				})
@@ -313,7 +325,7 @@ func decode(r io.RuneScanner, val reflect.Value) {
 					}
 					decodeArray(r, func() {
 						mValPtr := reflect.New(typ.Elem())
-						decode(r, mValPtr.Elem())
+						decode(r, mValPtr.Elem(), cfg)
 						val.Set(reflect.Append(val, mValPtr.Elem()))
 					})
 				default:
@@ -324,7 +336,7 @@ func decode(r io.RuneScanner, val reflect.Value) {
 			i := 0
 			decodeArray(r, func() {
 				mValPtr := reflect.New(typ.Elem())
-				decode(r, mValPtr.Elem())
+				decode(r, mValPtr.Elem(), cfg)
 				val.Index(i).Set(mValPtr.Elem())
 				i++
 			})
@@ -332,7 +344,7 @@ func decode(r io.RuneScanner, val reflect.Value) {
 			if val.IsNil() {
 				val.Set(reflect.New(typ.Elem()))
 			}
-			decode(r, val.Elem())
+			decode(r, val.Elem(), cfg)
 		default:
 			panic(decodeError{&json.UnsupportedTypeError{
 				Type: typ,
@@ -401,20 +413,20 @@ func scanNumber(r io.RuneScanner, out io.Writer) {
 	}
 }
 
-func decodeAny(r io.RuneScanner) any {
+func decodeAny(r io.RuneScanner, cfg decodeConfig) any {
 	c := peekRune(r)
 	switch c {
 	case '{':
 		ret := make(map[string]any)
 		var nameBuf strings.Builder
 		decodeObject(r, &nameBuf, func() {
-			ret[nameBuf.String()] = decodeAny(r)
+			ret[nameBuf.String()] = decodeAny(r, cfg)
 		})
 		return ret
 	case '[':
 		ret := []any{}
 		decodeArray(r, func() {
-			ret = append(ret, decodeAny(r))
+			ret = append(ret, decodeAny(r, cfg))
 		})
 		return ret
 	case '"':
@@ -424,7 +436,15 @@ func decodeAny(r io.RuneScanner) any {
 	case '-', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9':
 		var buf strings.Builder
 		scanNumber(r, &buf)
-		return json.Number(buf.String())
+		num := json.Number(buf.String())
+		if cfg.useNumber {
+			return num
+		}
+		f64, err := num.Float64()
+		if err != nil {
+			panic(decodeError{err})
+		}
+		return f64
 	case 't', 'f':
 		return decodeBool(r)
 	case 'n':