multi_index_container and virtual list controls

Question

I'm having a hard time with the multi_index_container.

This is basically what I need:

• Virtual list control.
• Sort the items in multiple ways (so I wanted to use multi_index_container).
• Access items randomly, according to how they are sorted and displayed in the list control.
• Keep the original insertion/record order of the items.
• Move items around, insert and delete items in the list control (and update the container accordingly).

I have so far been using multiple vectors/maps in sync (display list positions mapped to real data, etc), so it would be really nice to move to multi_index_container.

I have tried to write a minimal version of my original code (or attempts to write it).

Thanks a lot for any help on this! :)

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

#include <cstring>

namespace bmi = boost::multi_index;
typedef unsigned int uint;

struct Item_t
{
public:
    Item_t(std::wstring name, uint quantity) : Name(name), Quantity(Quantity) {}

    std::wstring Name;
    uint Quantity;
    // more members here, such as item type, category, etc
};

struct record_order;
struct name_order;
struct quantity_order;

typedef bmi::multi_index_container<
    Item_t,
    bmi::indexed_by<
        bmi::random_access<>,
        bmi::sequenced<bmi::tag<record_order>>,
        bmi::ordered_non_unique<
            bmi::tag<name_order>,
            bmi::member<Item_t, std::wstring, &Item_t::Name>
        >,
        bmi::ordered_non_unique<
            bmi::tag<quantity_order>,
            bmi::member<Item_t, uint, &Item_t::Quantity>
        >
    >
> ItemContainer;

void populateContainer(ItemContainer& container)
{
    container.push_back(Item_t(L"Salmon roll", 3));
    container.push_back(Item_t(L"Chinese cola", 0));
    container.push_back(Item_t(L"Norwegian cap", 1));
    container.push_back(Item_t(L"Like-new socks", 3));
    container.push_back(Item_t(L"Empty bottle", 4));
    container.push_back(Item_t(L"Nice tie", 1));
    /* sorted:
        Chinese cola
        Empty bottle
        Like-new socks
        Nice tie
        Norwegian cap
        Salmon roll
    */
}

int wmain(int argc, wchar_t* argv[])
{
    ItemContainer container;
    populateContainer(container);

    // sort items to be displayed to the user, by Item_t::Name
    // Please see my comment regarding this
    container.rearrange(container.get<name_order>().begin());

    for (ItemContainer::iterator it = container.begin(), end_ = container.end(); it != end_; ++it)
    {
        std::wcout << it->Name << std::endl;
    }

    std::wcout << std::endl;

    {
        // get Item_t from container where position in displayed list (after sort) is 5
        const Item_t& item = *(container.begin() + 5);
        // "Salmon roll"
        std::wcout << item.Name << std::endl;
    }

    {
        // TODO: insert and sort automatically: Item_t(L"Another useless thing", 1)
        const Item_t& item = *(container.begin() + 5);
        // Need this to be "Norwegian cap"
        std::wcout << item.Name << std::endl;
    }

    return 0;
}