//Purpose:
//  See if an any can change the stored type with an assignment.
//
#include <boost/type_erasure/any.hpp>
#include <boost/type_erasure/typeid_of.hpp>
#include <boost/type_erasure/builtin.hpp>
#include <boost/mpl/vector.hpp>
#include <iostream>
#include <boost/utility/demangled_type_name.hpp>
#include <boost/any.hpp>

namespace mpl = boost::mpl;
namespace te = boost::type_erasure;
using te::_a;
using te::_b;

    typedef 
  mpl::vector
  < te::copy_constructible<_a>
  , te::copy_constructible<_b>
  , te::typeid_<_a>
  , te::typeid_<_b>
  > 
requirements;

typedef double value_t;
typedef value_t* value_ptr_t;
typedef int displacement_t;
typedef mpl::vector<_a,_b> placeholders;
typedef mpl::vector<value_ptr_t,displacement_t> types;
typedef mpl::map<
    mpl::pair<mpl::at_c<placeholders,0>::type, mpl::at_c<types,0>::type>,
    mpl::pair<mpl::at_c<placeholders,1>::type, mpl::at_c<types,1>::type>
> bindings_map_t;

void convert() {
    value_t array[5]={1,2,3,4,5};


  //Create arguments to constructors on stack:
    mpl::at<bindings_map_t,_a>::type stk_value_ptr_v=&array[0];
    mpl::at<bindings_map_t,_b>::type stk_displacement_v=2;
    
    te::static_binding<bindings_map_t> bindings_made=te::make_binding<bindings_map_t>();
  //Can default any be created?
    te::any<requirements,_a> bnd_value_ptr_v(stk_value_ptr_v,bindings_made);
    {
        std::type_info const& tinfo=te::typeid_of(bnd_value_ptr_v);
        std::cout
          <<"typeinfo(bnd_value_ptr_v)="
          <<utility::demangled_type_info(tinfo)
          <<"\n";
    }
    te::any<requirements, _b> bnd_displacement_v(stk_displacement_v,bindings_made);
    {
        std::type_info const& tinfo=te::typeid_of(bnd_displacement_v);
        std::cout
          <<"typeinfo(bnd_displacement_v)="
          <<utility::demangled_type_info(tinfo)
          <<"\n";
    }
    {//Show te::any cannot change it's type.
      //#define SHOW_TE_FIXED_TYPE
      #ifdef SHOW_TE_FIXED_TYPE
        //the following code causes compile failure:
        bnd_value_ptr_v=bnd_displacement_v;//see what happens with assignment from diff type.
        std::type_info const& tinfo=te::typeid_of(bnd_value_ptr_v);
        std::cout
          <<"typeinfo(bnd_value_ptr_v=bnd_displacement_v)="
          <<utility::demangled_type_info(tinfo)
          <<"\n";
      #endif
    }
    {//In contrast, show boost::any can change its type.
        ::boost::any a_any;
        a_any=stk_displacement_v;
        std::cout
          <<"a_any=stk_displacement_v; any_cast<displacement_t>="
          <<::boost::any_cast<displacement_t>(&a_any)
          <<"\n";
        a_any=stk_value_ptr_v;
        std::cout
          <<"a_any=stk_value_ptr_v; any_cast<displacement_t>="
          <<::boost::any_cast<displacement_t>(&a_any)
          <<"; any_cast<value_ptr_t>="
          <<::boost::any_cast<value_ptr_t>(&a_any)
          <<"\n";
    }
}

int main()
{
    convert();
    return 0;
}