> gl_set_search O(n) O(1)
>
> Here the search method returns a void *, with value (void*)-1
> denoting "not found". Hmm, or should the search method better
> take a 'bool *' argument???
>
> If 'gl_set_search' is merely testing the membership of an element in a
> set, would not suffice to make it to return a boolean value, like in:
>
> bool gl_set_search (void *key);
I think the goal of this function is to return the single (first?)
KEY-matching entry from the set, or some special value if there's no
match.
The returned entry would be something like 'gl_list_node_t', right?
The primary use of a 'gl_list_node_t' is to change its contained
value. That is something convenient in a list because a list is
effectively a mapping between a position and a value, where it is
useful to keep the position and change the value.
An unordered set is effectively a mapping between a key and a boolean
(membership) so I am not sure what would be the benefit of returning
something like 'gl_set_node_t' instead of the boolean directly. In
case we want to change the membership status for some key then we
simply check and remove/insert.
However, that interface is subtly limiting, as Bruno appears to
have realized. I would prefer one like this:
bool gl_set_search (..., void const *key, void **match);
so as not to limit the range of valid "void*" result values.
Then we could even insert and query for a "NULL" key
or a key with that special value, (void*)-1.
I also find your suggestion better than to pass a **bool parameter.
