C++ - how to create a multimap with 4 variables and 4 keys

I want to create a class like below

class enumClass
{
    int msdnEnum;
    std::string msdnEnumString; 
    int localEnum;
    std::string localEnumString;
}

std::set<enumClass_Objects> enums; // all msdnEnums are unique, same aplies to other three.

enums.find(given_msdnEnum)->FourthVariable;
enums.find(given_localEnum)->FirstVariable;
enums.find(given_msdnEnumStr)->anyVariable;
enums.find(given_localEnumStr)->anyVariable;

I referred boost::multiIndex. But I don't think that it helps on this case. Can anybody say the way to achieve this?

EDIT I am not that much good in reading template classes. As for as I am concerning I didn't find any "find" methods in multiIndex. I saw only sorting out 开发者_如何学Cthings in that example(the first basic example:link). Suggestions&advices are always welcomed

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boost multiindex is exactly what you need in this case. Construct four indexes for the four keys - I guess given you guarantee that they will all be unique, make them unique indexes (I believe only one of them can be hashed_unique, but I think you can make the other three ordered_unique), and then do your searches on the each index depending on what you are searching by.

---

Here's a simple example using boost.multi_index:

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

struct enumClass
{
  int msdnEnum;
  std::string msdnEnumString; 
  int localEnum;
  std::string localEnumString;
};

namespace bmi = boost::multi_index;

typedef bmi::multi_index_container<
  enumClass,
  bmi::indexed_by<
    bmi::ordered_unique<bmi::member<enumClass, int, &enumClass::msdnEnum> >,
    bmi::ordered_unique<bmi::member<enumClass, std::string, &enumClass::msdnEnumString> >,
    bmi::ordered_unique<bmi::member<enumClass, int, &enumClass::localEnum> >,
    bmi::ordered_unique<bmi::member<enumClass, std::string, &enumClass::localEnumString> >
  >
> enumClassSet;

int main()
{
  enumClassSet enums;
  enums.get<0>().find(/*given_msdnEnum*/);     // index 0 is enumClass::msdnEnum
  enums.get<1>().find(/*given_msdnEnumStr*/);  // index 1 is enumClass::msdnEnumString
  enums.get<2>().find(/*given_localEnum*/);    // index 2 is enumClass::localEnum
  enums.get<3>().find(/*given_localEnumStr*/); // index 3 is enumClass::localEnumString
}

Tag classes could be used to access the indices by name rather than ordinal index as well, usage of which would look like this:

struct byMsdnEnum;
struct byMsdnEnumStr;
struct byLocalEnum;
struct byLocalEnumStr;

typedef bmi::multi_index_container<
  enumClass,
  bmi::indexed_by<
    bmi::ordered_unique<bmi::tag<byMsdnEnum>, bmi::member<enumClass, int, &enumClass::msdnEnum> >,
    bmi::ordered_unique<bmi::tag<byMsdnEnumStr>, bmi::member<enumClass, std::string, &enumClass::msdnEnumString> >,
    bmi::ordered_unique<bmi::tag<byLocalEnum>, bmi::member<enumClass, int, &enumClass::localEnum> >,
    bmi::ordered_unique<bmi::tag<byLocalEnumStr>, bmi::member<enumClass, std::string, &enumClass::localEnumString> >
  >
> enumClassSet;

int main()
{
  enumClassSet enums;
  enums.get<byMsdnEnum>().find(/*given_msdnEnum*/);
  enums.get<byMsdnEnumStr>().find(/*given_msdnEnumStr*/);
  enums.get<byLocalEnum>().find(/*given_localEnum*/);
  enums.get<byLocalEnumStr>().find(/*given_localEnumString*/);
}

The difference between the two approaches is purely aesthetic, and of course the tag classes could be named whatever you want rather than byMsdnEnum, etc. Also note that hashed indices could be used rather than ordered indices, which would give your indices the behavior of std::unordered_map rather than std::map.

---

Is there a reason why you cannot use 2 maps? ( std::map< int, std::string> ). If you need to find both of the string variables by any of those two keys, then you could solve it by having a map that would pair for example msdnEnum with both strings and then have a map that would pair localEnum with msdnEnum. Than any lookup via msdnEnum would be done directly and a lookup via localEnum would first do a translation to msdnEnum and then do a direct lookup.