Re: [Boost-users] A doubt in Boost multi index

Subject: Re: [Boost-users] A doubt in Boost multi index
From: Gokulakannan Somasundaram (gokul007_at_[hidden])
Date: 2010-07-30 09:24:51

Thanks a lot. I could make sense of your first one with some difficulty.
I am trying to understand the next one. Anyways, i will just use it as
template to solve my problem.

Thanks,
Gokul.

On Fri, Jul 30, 2010 at 8:35 PM, <joaquin_at_[hidden]> wrote:

> Gokulakannan Somasundaram escribió:
>
>
>>
>> On Fri, Jul 30, 2010 at 7:49 PM, <joaquin_at_[hidden] <mailto:joaquin_at_[hidden]>>
>> wrote:
>>
>>    Gokulakannan Somasundaram escribió:
>>
>>        Hi,
>>          In boost multi-index, can i verify whether a particular
>>        index type is
>>         ordered/not or not through meta programming?  There are the
>>        ordered
>>         indexes, hash indexes, sequence indexes etc. Can i find them out
>>         through meta programming?
>>
>>
>>    You can if you're given the multi_index_containr type and the position
>>    of the index:
>>
>>
>>  Thanks a lot. Is it possible to do the same with named tags?
>>
>>
> With a little more effort:
>
>
>  #include <boost/multi_index/ordered_index.hpp>
>  #include <boost/mpl/at.hpp>
>  #include <boost/mpl/bool.hpp>
>
>  template<typename IndexSpecifier>
>  struct is_ordered_index_impl:boost::mpl::false_{};
>
>  template<typename KeyFromValue,typename Compare>
>  struct is_ordered_index_impl<
>   boost::multi_index::ordered_unique<KeyFromValue,Compare>
>  >:boost::mpl::true_{};
>
>  template<typename KeyFromValue,typename Compare>
>  struct is_ordered_index_impl<
>   boost::multi_index::ordered_non_unique<KeyFromValue,Compare>
>  >:boost::mpl::true_{};
>
>  template<typename MultiIndexContainer,int N>
>  struct is_ordered_index:
>   is_ordered_index_impl<
>     typename boost::mpl::at_c<
>       typename MultiIndexContainer::index_specifier_type_list,
>       N
>     >::type
>   >
>  {};
>
>  #include <boost/mpl/begin_end.hpp>
>  #include <boost/mpl/contains.hpp>
>  #include <boost/mpl/distance.hpp>
>  #include <boost/mpl/find_if.hpp>
>
>  template<typename Index>
>  struct tag_list
>  {
>   typedef typename Index::tag_list type;
>  };
>
>  template<typename Tag,typename IndexList>
>  struct tag_pos:
>   boost::mpl::distance<
>     typename boost::mpl::begin<IndexList>::type,
>     typename boost::mpl::find_if<
>       IndexList,
>       boost::mpl::contains<tag_list<boost::mpl::_>,Tag>
>     >::type
>   >
>  {};
>
>  template<typename MultiIndexContainer,typename Tag>
>  struct is_ordered_index_with_tag:
>   is_ordered_index<
>     MultiIndexContainer,
>     tag_pos<Tag,typename MultiIndexContainer::index_type_list>::value
>
>   >
>  {};
>
>
>  /* testing */
>
>  #include <boost/multi_index_container.hpp>
>  #include <boost/multi_index/sequenced_index.hpp>
>  #include <boost/multi_index/hashed_index.hpp>
>  #include <boost/multi_index/identity.hpp>
>  #include <boost/mpl/assert.hpp>
>
>  using namespace boost::multi_index;
>
>  typedef multi_index_container<
>   int,
>   indexed_by<
>     ordered_unique<tag<struct i0>,identity<int> >,
>     ordered_non_unique<tag<struct i1>, identity<int> >,
>     hashed_unique<tag<struct i2>, identity<int> >,
>     hashed_non_unique<tag<struct i3>, identity<int> >,
>     sequenced<tag<struct i4> >
>
>   >
>  > multi_t;
>
>  BOOST_MPL_ASSERT    ((is_ordered_index<multi_t,0>));
>  BOOST_MPL_ASSERT    ((is_ordered_index<multi_t,1>));
>  BOOST_MPL_ASSERT_NOT((is_ordered_index<multi_t,2>));
>  BOOST_MPL_ASSERT_NOT((is_ordered_index<multi_t,3>));
>  BOOST_MPL_ASSERT_NOT((is_ordered_index<multi_t,4>));
>
>  BOOST_MPL_ASSERT    ((is_ordered_index_with_tag<multi_t,i0>));
>  BOOST_MPL_ASSERT    ((is_ordered_index_with_tag<multi_t,i1>));
>  BOOST_MPL_ASSERT_NOT((is_ordered_index_with_tag<multi_t,i2>));
>  BOOST_MPL_ASSERT_NOT((is_ordered_index_with_tag<multi_t,i3>));
>  BOOST_MPL_ASSERT_NOT((is_ordered_index_with_tag<multi_t,i4>));
>
>  int main(){}
>
>
> Joaquín M López Muñoz
> Telefónica, Investigación y Desarrollo
> _______________________________________________
> Boost-users mailing list
> Boost-users_at_[hidden]
> http://lists.boost.org/mailman/listinfo.cgi/boost-users
>