[Boost-users] [multi_index] sorted iteration of values

Subject: [Boost-users] [multi_index] sorted iteration of values
From: Mathieu Champlon (m.champlon_at_[hidden])
Date: 2013-09-04 01:15:53

Hello,

I'm trying to use Boost.MultiIndex to store my data. The idea is to have 
a kind of bidirectional multimap (I initially started with Boost.BiMap) 
which could model :

std::multimap< SomeType*, std::set< int > > left;
std::multimap< int, SomeType*> right;

I'll need to :
. insert obviously
. remove all ints based on a SomeType*
. remove one given (SomeType*,int)
. for a given int iterate on all SomeType*
. for a given SomeType* iterate in order on all ints

What I have so far is :

     typedef SomeType* First;
     typedef int Second;

     struct Value
     {
         First first;
         Second second;
     };

     boost::multi_index::multi_index_container<
             Value,
             boost::multi_index::indexed_by<
                 boost::multi_index::ordered_unique<
                     boost::multi_index::composite_key<
                         Value,
                         boost::multi_index::member<
                             Value, First, &Value::first >,
                         boost::multi_index::member<
                             Value, Second, &Value::second >
                     >
                 >,
                 boost::multi_index::ordered_non_unique<
                     boost::multi_index::member<
                         Value, Second, &Value::second >
                 >,
                 boost::multi_index::ordered_non_unique<
                     boost::multi_index::member<
                         Value, First, &Value::first >
                 >
             >
         > data;

This works, except for the ints iteration based on a given SomeType* 
because I need them to be sorted, and they're not, e.g.

     auto range = data.get< 2 >().equal_range( someTypePtr );
     for( auto it = range.first; it != range.second; ++it )
         ;

does not iterate in a sorted order.

Is there a way to achieve this without manually sorting the iterated 
values ?

Thank you !
MAT.