Does C++ have a bijective map type?

Does C++ have anything which behaves like std::map<T1, T2>, but permitting not only looking for a T1 value to find its associated T2 value, but also to look for a particular T2 value to find its associated T1 value? (Which would mean values on both sides need to be unique.)

boost::bimap is a data structure that behaves exactly the way you describe.

• Both sets of elements must be unique
• boost::bimap<T1,T2>::left provides an interface that closely matches std::map<T1,T2>, including all T1-based lookup
• boost::bimap<T1,T2>::right provides an interface that closely matches std::map<T2,T1>, including all T2-based lookup
• Because all elements must be unique, one difference in the interface is that all elements are const. You can add and remove, but you can not modify in-place.