if n == 0 {
return
}
+
+ b.lastByte = -1
+ b.lastRuneSize = -1
+
remain := n
for {
skip := b.Buffered()
// UnreadByte unreads the last byte. Only the most recently read byte can be unread.
//
// UnreadByte returns an error if the most recent method called on the
-// Reader was not a read operation. Notably, Peek is not considered a
-// read operation.
+// Reader was not a read operation. Notably, Peek, Discard, and WriteTo are not
+// considered read operations.
func (b *Reader) UnreadByte() error {
if b.lastByte < 0 || b.r == 0 && b.w > 0 {
return ErrInvalidUnreadByte
// If the underlying reader supports the WriteTo method,
// this calls the underlying WriteTo without buffering.
func (b *Reader) WriteTo(w io.Writer) (n int64, err error) {
+ b.lastByte = -1
+ b.lastRuneSize = -1
+
n, err = b.writeBuf(w)
if err != nil {
return
}
}
+func TestNoUnreadRuneAfterDiscard(t *testing.T) {
+ br := NewReader(strings.NewReader("example"))
+ br.ReadRune()
+ br.Discard(1)
+ if err := br.UnreadRune(); err == nil {
+ t.Error("UnreadRune didn't fail after Discard")
+ }
+}
+
+func TestNoUnreadByteAfterDiscard(t *testing.T) {
+ br := NewReader(strings.NewReader("example"))
+ br.ReadByte()
+ br.Discard(1)
+ if err := br.UnreadByte(); err == nil {
+ t.Error("UnreadByte didn't fail after Discard")
+ }
+}
+
+func TestNoUnreadRuneAfterWriteTo(t *testing.T) {
+ br := NewReader(strings.NewReader("example"))
+ br.WriteTo(io.Discard)
+ if err := br.UnreadRune(); err == nil {
+ t.Error("UnreadRune didn't fail after WriteTo")
+ }
+}
+
+func TestNoUnreadByteAfterWriteTo(t *testing.T) {
+ br := NewReader(strings.NewReader("example"))
+ br.WriteTo(io.Discard)
+ if err := br.UnreadByte(); err == nil {
+ t.Error("UnreadByte didn't fail after WriteTo")
+ }
+}
+
func TestUnreadByte(t *testing.T) {
segments := []string{"Hello, ", "world"}
r := NewReader(&StringReader{data: segments})