Tie::Hash::TwoWay will take a list of one-way associations and
transparently create their reverse.  For instance, say you have a list
of machines, and a list of classes that each machine belongs to.
Tie::Hash::TwoWay will take the machines, one by one, with an associated
array reference of class names, and build the reverse mapping of classes
to machines.  All the mappings are stored as hashes.  You can access the
secondary mappings as if they were hash keys in their own right.

WWW: https://metacpan.org/release/Tie-Hash-TwoWay