#include <boost/multi_index_container.hpp>
#include <boost/multi_index/ordered_index.hpp>
#include <boost/multi_index/member.hpp>
#include <iostream>

template<typename Index>
std::pair<typename Index::iterator,bool>
replacing_insert(Index& i,const typename Index::value_type& x)
{
  std::pair<typename Index::iterator,bool> res=i.insert(x);
  if(!res.second)res.second=i.replace(res.first,x);
  return res;
}

struct foo
{
  foo(int x,int y,int z):x(x),y(y),z(z){}
  int x,y,z;
};

using namespace boost::multi_index;

typedef multi_index_container<
  foo,
  indexed_by<
    ordered_unique<member<foo,int,&foo::x> >,
    ordered_unique<member<foo,int,&foo::y> >
  >
> multi_index_t;

int main()
{
  multi_index_t m;
  
  m.insert(foo(1,0,10));
  m.insert(foo(0,1,11));
  
  std::pair<multi_index_t::iterator,bool> p;
  
  p=m.insert(foo(1,0,20));
  std::cout<<p.second<<", "<<p.first->z<<std::endl;
  
  p=replacing_insert(m,foo(1,1,20));
  std::cout<<p.second<<", "<<p.first->z<<std::endl;

  p=replacing_insert(m,foo(1,0,20));
  std::cout<<p.second<<", "<<p.first->z<<std::endl;
}