Re: [PATCH 1/5] rbtree: add postorder iteration functions

[Cody P Schafer]

On 07/29/2013 08:01 AM, Seth Jennings wrote:
> On Fri, Jul 26, 2013 at 02:13:39PM -0700, Cody P Schafer wrote:
> > diff --git a/lib/rbtree.c b/lib/rbtree.c
> > index c0e31fe..65f4eff 100644
> > --- a/lib/rbtree.c
> > +++ b/lib/rbtree.c
> > @@ -518,3 +518,43 @@ void rb_replace_node(struct rb_node *victim, struct rb_node *new,
> >   	*new = *victim;
> >   }
> >   EXPORT_SYMBOL(rb_replace_node);
> > +
> > +static struct rb_node *rb_left_deepest_node(const struct rb_node *node)
> > +{
> > +	for (;;) {
> > +		if (node->rb_left)
> > +			node = node->rb_left;
>
> Assigning to an argument passed as const seems weird to me.  I would
> think it shouldn't compile but it does.  I guess my understanding of
> const is incomplete.

Ya, that is due to const's binding:
	const struct rb_node *node1; // the thing pointed to is const
	const struct rb_node node2;  // node is const
	struct rb_node *const node3; // node is const
	const struct rb_node *const node4; // both node and the thing
					   // pointed too are const

And so ends up being perfectly legal (I use the first case listed here).

> > +		else if (node->rb_right)
> > +			node = node->rb_right;
> > +		else
> > +			return (struct rb_node *)node;
> > +	}
> > +}
> > +
> > +struct rb_node *rb_next_postorder(const struct rb_node *node)
> > +{
> > +	const struct rb_node *parent;
> > +	if (!node)
> > +		return NULL;
> > +	parent = rb_parent(node);
>
> Again here.
>
> Seth

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