BiMap

BiMap.h

#include <map>

using std::map;

/* This is a two-way (or bi-directional) map similar to the Boost bimap.
   It enables a caller to look up value by key, or a key by value,
   which makes it easy to translate to/from a pair of types.
   For instance, we can retrieve the name of an enumerator or integer value
   and translate it into an integer; and then to update it, we translate it
   from integer back into its name to store in the config file.
   See https://www.boost.org/doc/libs/1_67_0/libs/bimap/doc/html/boost_bimap/one_minute_tutorial.html
*/
template<typename X, typename Y> struct BiMap {
    map<X, Y> m_xy_map;
    map<Y, X> m_yx_map;
    void Insert(X const& key, Y const& value);
    Y GetValue(X const& key);
    X GetKey(Y const& value);
};

template<typename X, typename Y>
inline void BiMap<X, Y>::Insert(X const& key, Y const& value) {
    m_xy_map.insert({ key, value });
    m_yx_map.insert({ value, key });
}

template<typename X, typename Y>
inline Y BiMap<X, Y>::GetValue(X const& key) {
    return m_xy_map[key];
}

template<typename X, typename Y>
inline X BiMap<X, Y>::GetKey(Y const& value) {
    return m_yx_map[value];
}