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/eval.c b/eval.c
index e94b4c14..7f3e2b23 100644
--- a/eval.c
+++ b/eval.c
@@ -6970,6 +6970,11 @@ void eval_init(void)
   reg_fun(intern(lit("seq-begin"), user_package), func_n1(seq_begin));
   reg_fun(intern(lit("seq-next"), user_package), func_n2(seq_next));
   reg_fun(intern(lit("seq-reset"), user_package), func_n2(seq_reset));
+  reg_fun(intern(lit("iter-begin"), user_package), func_n1(iter_begin));
+  reg_fun(intern(lit("iter-more"), user_package), func_n1(iter_more));
+  reg_fun(intern(lit("iter-item"), user_package), func_n1(iter_item));
+  reg_fun(intern(lit("iter-step"), user_package), func_n1(iter_step));
+  reg_fun(intern(lit("iter-reset"), user_package), func_n2(iter_reset));
 
   reg_fun(intern(lit("rcons"), user_package), func_n2(rcons));
   reg_fun(intern(lit("rangep"), user_package), func_n1(rangep));