http://stackoverflow.com/questions/11408934/using-a-stdtuple-as-key-for-stdunordered-map

http://stackoverflow.com/questions/20834838/using-tuple-in-unordered-map

http://coliru.stacked-crooked.com/a/dede823b40af4662

The sample :

    #include <iostream>
    #include <string>
    #include <tuple>
    #include <utility>
    #include <unordered_map>

    namespace N {
        typedef std::tuple<int, char, char> key_t;
        struct key_hash : public std::unary_function<key_t, std::size_t>
        {
            std::size_t operator()(const key_t& k) const
            {
                return std::get<0>(k) ^ std::get<1>(k) ^ std::get<2>(k);
            }
        };

        struct key_equal : public std::binary_function<key_t, key_t, bool>
        {
            bool operator()(const key_t& v0, const key_t& v1) const
            {
                return (
                    std::get<0>(v0) == std::get<0>(v1) &&
                    std::get<1>(v0) == std::get<1>(v1) &&
                    std::get<2>(v0) == std::get<2>(v1)
                );
            }
        };

        struct data
        {
            std::string x;
        };

        typedef std::unordered_map<const key_t,data,key_hash,key_equal> map_t;

    }

    int main()
    {
        using namespace N;

        map_t m;
        data d;
        d.x = "test data";
        m[std::make_tuple(1, 'a', 'b')] = d;
        auto itr = m.find(std::make_tuple(1, 'a', 'b'));
        if (m.end() != itr)
        {
            std::cout << "x: " << itr->second.x;
        }
        return 0;
    }

g++ --std=c++0x unordered_test.cpp -o unordered_test.exe

./unordered_test.exe

x: test data

 

 

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