Re-added SliceReaderAt

gigaparsec.go

@@ -116,6 +116,22 @@ type ReaderAt[T any] interface {
 	ReadAt(p []T, off int64) (n int, err error)
 }
 
+type SliceReaderAt[T any] []T
+
+func (s SliceReaderAt[T]) ReadAt(dst []T, off int64) (n int, err error) {
+	if off < 0 {
+		return 0, errors.New("SliceReaderAt.ReadAt: negative offset")
+	}
+	if off >= int64(len(s)) {
+		return 0, io.EOF
+	}
+	n = copy(dst, s[off:])
+	if n < len(dst) {
+		err = io.EOF
+	}
+	return n, err
+}
+
 func MakeState[In any](r ReaderAt[In]) State[In] {
 	return State[In]{r: r}
 }