decode: Add a .maybeDecodeNull helper

This doesn't help much now, but it will help next commit when I add a
*DecodeError return value from .peekRuneType().

1 files changed, 26 insertions, 16 deletions

diff --git a/decode.go b/decode.go
index 60667c0..73d15c5 100644
--- a/decode.go
+++ b/decode.go
@@ -427,8 +427,8 @@ func (dec *Decoder) decode(val reflect.Value, nullOK bool) (_err *DecodeError) {
 			return dec.newTypeError(t.JSONType(), reflect.PointerTo(typ), err)
 		}
 	case val.CanAddr() && reflect.PointerTo(typ).Implements(textUnmarshalerType):
-		if nullOK && dec.peekRuneType() == jsonparse.RuneTypeNullN {
-			return dec.decodeNull()
+		if ok, err := dec.maybeDecodeNull(nullOK); ok {
+			return err
 		}
 		var buf bytes.Buffer
 		if err := dec.decodeString(reflect.PointerTo(typ), &buf); err != nil {
@@ -441,8 +441,8 @@ func (dec *Decoder) decode(val reflect.Value, nullOK bool) (_err *DecodeError) {
 	default:
 		switch kind := typ.Kind(); kind {
 		case reflect.Bool:
-			if nullOK && dec.peekRuneType() == jsonparse.RuneTypeNullN {
-				return dec.decodeNull()
+			if ok, err := dec.maybeDecodeNull(nullOK); ok {
+				return err
 			}
 			b, err := dec.decodeBool(typ)
 			if err != nil {
@@ -450,8 +450,8 @@ func (dec *Decoder) decode(val reflect.Value, nullOK bool) (_err *DecodeError) {
 			}
 			val.SetBool(b)
 		case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
-			if nullOK && dec.peekRuneType() == jsonparse.RuneTypeNullN {
-				return dec.decodeNull()
+			if ok, err := dec.maybeDecodeNull(nullOK); ok {
+				return err
 			}
 			var buf strings.Builder
 			if err := dec.scanNumber(typ, &buf); err != nil {
@@ -463,8 +463,8 @@ func (dec *Decoder) decode(val reflect.Value, nullOK bool) (_err *DecodeError) {
 			}
 			val.SetInt(n)
 		case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
-			if nullOK && dec.peekRuneType() == jsonparse.RuneTypeNullN {
-				return dec.decodeNull()
+			if ok, err := dec.maybeDecodeNull(nullOK); ok {
+				return err
 			}
 			var buf strings.Builder
 			if err := dec.scanNumber(typ, &buf); err != nil {
@@ -476,8 +476,8 @@ func (dec *Decoder) decode(val reflect.Value, nullOK bool) (_err *DecodeError) {
 			}
 			val.SetUint(n)
 		case reflect.Float32, reflect.Float64:
-			if nullOK && dec.peekRuneType() == jsonparse.RuneTypeNullN {
-				return dec.decodeNull()
+			if ok, err := dec.maybeDecodeNull(nullOK); ok {
+				return err
 			}
 			var buf strings.Builder
 			if err := dec.scanNumber(typ, &buf); err != nil {
@@ -489,8 +489,8 @@ func (dec *Decoder) decode(val reflect.Value, nullOK bool) (_err *DecodeError) {
 			}
 			val.SetFloat(n)
 		case reflect.String:
-			if nullOK && dec.peekRuneType() == jsonparse.RuneTypeNullN {
-				return dec.decodeNull()
+			if ok, err := dec.maybeDecodeNull(nullOK); ok {
+				return err
 			}
 			var buf strings.Builder
 			if typ == numberType {
@@ -559,8 +559,8 @@ func (dec *Decoder) decode(val reflect.Value, nullOK bool) (_err *DecodeError) {
 				val.Set(reflect.ValueOf(v))
 			}
 		case reflect.Struct:
-			if nullOK && dec.peekRuneType() == jsonparse.RuneTypeNullN {
-				return dec.decodeNull()
+			if ok, err := dec.maybeDecodeNull(nullOK); ok {
+				return err
 			}
 			index := jsonstruct.IndexStruct(typ)
 			var nameBuf strings.Builder
@@ -780,8 +780,8 @@ func (dec *Decoder) decode(val reflect.Value, nullOK bool) (_err *DecodeError) {
 				}
 			}
 		case reflect.Array:
-			if nullOK && dec.peekRuneType() == jsonparse.RuneTypeNullN {
-				return dec.decodeNull()
+			if ok, err := dec.maybeDecodeNull(nullOK); ok {
+				return err
 			}
 			i := 0
 			n := val.Len()
@@ -1212,3 +1212,13 @@ func (dec *Decoder) decodeNull() *DecodeError {
 	dec.expectRune('l', jsonparse.RuneTypeNullL2)
 	return nil
 }
+
+func (dec *Decoder) maybeDecodeNull(nullOK bool) (ok bool, err *DecodeError) {
+	if nullOK {
+		t := dec.peekRuneType()
+		if t == jsonparse.RuneTypeNullN {
+			return true, dec.decodeNull()
+		}
+	}
+	return false, nil
+}