seq_iter: integers and ranges become iterable.

I think with the iter-begin API, we have the the "Maxwell's
Equations of Iteration". This not only works well for conses,
but it extends to numbers and ranges.

* lib.h (seq_iter_t): New union member ul, containing a new
member lim. existing len member moved into ul union.
* lib.c (seq_iter_get_vec, seq_iter_peek_vec): Adjust access
of len, now wrapped in union.
(seq_iter_get_range_cnum, seq_iter_peek_range_cnum,
seq_iter_get_range_chr, seq_iter_peek_range_chr,
seq_iter_get_range_bignum, seq_iter_peek_range_bignum,
seq_iter_get_chr, seq_iter_peek_chr, seq_iter_get_num,
seq_iter_peek_num): New static functions.
(seq_iter_init_with_info): Support RNG object, further
classifying the iteration based on the type of the from
element. Support numbers and characters as iterable.
(iter_begin, iter_more, iter_item, iter_step, iter_reset):
Support numbers directly as unencapsulated iterators.

1 files changed, 4 insertions, 1 deletions

diff --git a/lib.h b/lib.h
index 37180204..3463969b 100644
--- a/lib.h
+++ b/lib.h
@@ -391,7 +391,10 @@ typedef struct seq_iter {
     val iter;
     cnum index;
   } ui;
-  cnum len;
+  union {
+    val lim;
+    cnum len;
+  } ul;
   int (*get)(struct seq_iter *, val *pval);
   int (*peek)(struct seq_iter *, val *pval);
 } seq_iter_t;