tree: tree iterators.

* tree.c (struct tree_diter): New struct type.
(tree_iter_s): New symbol variable.
(tree_iter_mark): New static function.
(tree_iter_ops): New static struct.
(tree_begin, tree_next): New functions.
(tree_init): Initialize tree_iter_s; register tree-begin and
tree-next intrinsics.

* tree.h (tree_begin, tree_next): Declared.

1 files changed, 2 insertions, 0 deletions

diff --git a/tree.h b/tree.h
index 32f846e9..6233a0fc 100644
--- a/tree.h
+++ b/tree.h
@@ -36,4 +36,6 @@ val right(val node);
 val key(val node);
 val tree(val keys, val key_fn, val less_fn, val equal_fn);
 val treep(val obj);
+val tree_begin(val tree);
+val tree_next(val iter);
 void tree_init(void);