itree.c: Improve division between tree and iterator

* src/buffer.c (delete_all_overlays): Add comment.

* src/itree.c (struct interval_generator): New fields `running`,
`file`, and `line` moved from `interval_tree`.
(interval_stack_push_flagged): Adjust comment to resolve a FIXME.
(interval_tree_clear): Replace assignment with an a
(interval_tree_iter_next): Delete function.
(interval_tree_clear): Don't set `iter_running` here any more.
(interval_generator_create): Set it here instead.
(interval_tree_iter_start): Fetch `iter` once and for all.
(interval_generator_narrow): Mark it as non-static.
(interval_tree_iter_next, interval_tree_iter_narrow):
Delete functions.  Inline their old bodies in the callers.
(interval_tree_iter_finish): Take the iter rather than
the whole tree.  Adjust all callers.
(interval_generator_next): Move `running `assertion here from
`interval_tree_iter_next`.

* src/buffer.h: Adjust accordingly.

* src/itree.h (struct interval_tree): Remove fields `iter_running`,
`file`, and `line`, moved to `interval_generator`.
(interval_generator_narrow): Replace `interval_tree_iter_narrow`.

1 files changed, 8 insertions, 0 deletions

diff --git a/src/buffer.c b/src/buffer.c
index 2f026584bbf..19937216ed5 100644
--- a/src/buffer.c
+++ b/src/buffer.c
@@ -921,6 +921,14 @@ delete_all_overlays (struct buffer *b)
   if (! b->overlays)
     return;
 
+  /* FIXME: This loop sets the overlays' `buffer` field to NULL but
+     doesn't set the interval_nodes' `parent`, `left` and `right`
+     fields accordingly.  I believe it's harmless, but a bit untidy since
+     other parts of the code are careful to set those fields to NULL when
+     the overlay is deleted.
+     Of course, we can't set them to NULL from within the iteration
+     because the iterator may need them (tho we could if we added
+     an ITREE_POST_ORDER iteration order).  */
   buffer_overlay_iter_start (b, PTRDIFF_MIN, PTRDIFF_MAX, ITREE_ASCENDING);
   while ((node = buffer_overlay_iter_next (b)))
     {