New style iteration functions.

iter-begin provides a paradigm for iteration that is more
compatible with lists. If the sequence is a list, then the
list itself is returned as the iterator, and the other
functions are basicaly wrappers for car/cdr and null testing.
Yet the API is defined in such a way that other objects can be
iterated with good efficiency, at the cost of allocating a new
iterator object (which can be re-used).

* eval.c (eval_init): Register iter-begin, iter-more,
iter-item, iter-step and iter-reset.

* lib.c (seq_iter_init_with_info): New static function.
(seq_iter_init): Now a thin wrapper for
seq_iter_init_with_info.
(iter_begin, iter_more, iter_item, iter_step, iter_reset): New
functions.

* lib.h (iter_begin, iter_more, iter_item, iter_step,
iter_reset): New functions.

* txr.1: Documented.

1 files changed, 5 insertions, 0 deletions

diff --git a/lib.h b/lib.h
index d23484c1..37180204 100644
--- a/lib.h
+++ b/lib.h
@@ -556,6 +556,11 @@ void seq_setpos(val self, seq_iter_t *it, val pos);
 val seq_begin(val obj);
 val seq_next(val iter, val end_val);
 val seq_reset(val iter, val obj);
+val iter_begin(val obj);
+val iter_more(val iter);
+val iter_item(val iter);
+val iter_step(val iter);
+val iter_reset(val iter, val obj);
 val throw_mismatch(val self, val obj, type_t);
 INLINE val type_check(val self, val obj, type_t typecode)
 {