Re: [boost] [unordered] request for ways to get more space efficient allocations

From: Daniel James (daniel_james_at_[hidden])
Date: 2008-04-21 16:24:04

On 21/04/2008, Thorsten Ottosen <thorsten.ottosen_at_[hidden]> wrote:
> Daniel James skrev:
>  > An alternative that has some appeal is letting the user specify a
>  > policy class to control the bucket count. Although I'm not sure how
>  > that would play with the standard.
>
> Poor, probably.
>
>  I guess for cases where I know the intergers fall in the range, say,
>  [0,64], I can just use vector<optional<unsigned>>.

Thinking about it some more, I could create a trait class for the hash function.

template <class T> struct is_good_hash : public boost::mpl::false_ {};
template <> struct is_good_hash<groovy_hash> : public boost::mpl::true_ {};

And use power of 2 tables when the trait is true.

Daniel