nullify and empty: convert to seq_info.

Issues: (nullify 1..1) doesn't return nil as it
should, and (empty 1) fails.

* lib.c (seq_info): Since we would like nullify to use
seq_info, seq_info cannot call nullify. Transplant the probing
of the nullify method out of nullify and into here.
(nullify): Obtain a seq_info_t on the object. If it's not a
sequence and is not range, then just return the object.
Otherwise obtain a seq_iter_t sequence and peek whether it has
a next item.
(empty): Similarly, obtain an iterator and peek.
Definition of empty is relocated to be next to nullify.

* lib.h: Relocate declaration of empty, also.

0 files changed, 0 insertions, 0 deletions