Fix those now-failing error checks

1 files changed, 29 insertions, 0 deletions

diff --git a/decode.go b/decode.go
index a17a572..52fcb5e 100644
--- a/decode.go
+++ b/decode.go
@@ -121,6 +121,26 @@ func Decode(r interface {
 	return NewDecoder(r).Decode(ptr)
 }
 
+// DecodeThenEOF is like decode, but emits an error if there is extra data after the JSON.
+func DecodeThenEOF(r interface {
+	io.Reader
+	io.RuneScanner
+}, ptr any) error {
+	dec := NewDecoder(r)
+	if err := dec.Decode(ptr); err != nil {
+		return err
+	}
+	if c, _, err := r.ReadRune(); err == nil {
+		return &DecodeError{
+			Err: &DecodeSyntaxError{
+				Err:    fmt.Errorf("invalid character %q after top-level value", c),
+				Offset: dec.InputOffset(),
+			},
+		}
+	}
+	return nil
+}
+
 func (dec *Decoder) Decode(ptr any) (err error) {
 	ptrVal := reflect.ValueOf(ptr)
 	if ptrVal.Kind() != reflect.Pointer || ptrVal.IsNil() || !ptrVal.Elem().CanSet() {
@@ -147,6 +167,15 @@ func (dec *Decoder) Decode(ptr any) (err error) {
 		}
 	}()
 	dec.decode(ptrVal.Elem(), false)
+	for {
+		_, s, t, _ := dec.io.ReadRuneType()
+		if t == RuneTypeEOF || t == RuneTypeError {
+			if s > 0 {
+				dec.io.UnreadRune()
+			}
+			break
+		}
+	}
 	return nil
 }