Re: [Boost-users] [MultiIndex] As if one iterator

Subject: Re: [Boost-users] [MultiIndex] As if one iterator
From: Dan Bloomquist (danb_at_[hidden])
Date: 2010-06-07 15:26:24

Joaquin M Lopez Munoz wrote:
> Dan Bloomquist<danb<at>  lakeweb.net>  writes:
>
> Not sure whether this is what you'r after, but have you considered
> using adobe::any_iterator?
>
> http://stlab.adobe.com/classadobe_1_1any__iterator.html
>
> adobe::any_iterator is a polymorphic iterator wrapper so that
> you can use it to handle at run-time any iterator with the specified
> category (bidirectional, foward, etc.) Kind of like boost::any for
> general objects, but already specialized for the iterator interface.
>
>    
Hi Joaquin,
Thank you for the link. I'm on tangents right now but have/will look 
over these adobe headers. I have attempted to write my own based on 
itereator_facade. I've gotten all the members to work except for 
dereferance. I've looked every example I can find where it works, but in 
my case some iterator base gets called which is invalid. I've even tried 
overriding the arrow operator. In that case I land in operators.hhp with:

template <class T, class P, class B = ::boost::detail::empty_base<T> >
struct dereferenceable : B
{
   P operator->() const
   {
     return &*static_cast<const T&>(*this);
   }
};

  // next up the stack is, from,  multi_index/iter_adaptor.hpp:
   typedef typename Base::reference reference;

   reference operator*()const
   {
     return iter_adaptor_access::dereference(final());
   }

//Which gets me to this assert:
     BOOST_MULTI_INDEX_CHECK_DEREFERENCEABLE_ITERATOR(*this);

Yet my iterator class has all the multi_index buried in code. So I don't 
get what got compiled here or how

Best, Dan.

~~~ the iterator class

# include <boost/iterator/iterator_facade.hpp>
class RaOrderRecords;
class RaOrderRecordsIt
     :public boost::iterator_facade
<
         RaOrderRecordsIt
         ,ord_record_item const
         ,boost::bidirectional_traversal_tag
 >
{
     friend class boost::iterator_core_access;
     friend RaOrderRecords;
     //container
     RaOrderRecords* pParent;
     //this index
     RsOrderIndex::RecOrderIndex index;
     //iterators for proxy
     SP_it_adaptor_container spIterators;

public:
     //base( ) const { return *this; }
     RaOrderRecordsIt( RaOrderRecords* pPrnt, 
RsOrderIndex::RecOrderIndex inIdx );
     RaOrderRecordsIt( )
         :pParent( NULL )//for asserts
     { }
     void increment( );// { }
     bool equal( const RaOrderRecordsIt& f2 ) const;
     ord_record_item const& dereference( ) const;
     //ord_record_item& dereference( ) const;
     const ord_record_item* operator->( ) const;

     RaOrderRecordsIt begin( );
     RaOrderRecordsIt end( );
};