Re: [RFC] B+Tree library V2

[Johannes Berg <johannes@sipsolutions.net>]

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On Thu, 2009-01-08 at 17:24 +0100, Jörn Engel wrote:

> If you want to open-code it, you can use btree_lookup_less().  I added
> that function sometime last month.  Basically something like this:
> 	key = btree_last(head, geo);
> 	while (key) {
> 		/* do something with key */
> 		key = btree_lookup_less(head, geo, key);
> 	}

Ok, so looking deeper into this, how about adding

#define btree_for_each_key(head, geo, key, tmp)	\
	for (key = btree_last(head, geo), tmp = btree_lookup_less(head, geo, key);
	     key; key = tmp, tmp = btree_lookup_less(head, geo, key))

(and possibly some type-checking variants that hardcode the geo)

Does that seem correct? And would it be possible to provide btree_last()
that takes an void ** and fills it with the last entry, and the same for
lookup_less(), so we can write btree_for_each_entry() too?

johannes

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