bidirectional map

[Ellery Newcomer]

On 11/11/2013 05:14 PM, bioinfornatics wrote:
> Dear,
> I am looking for a bidirectional map i.e
> http://en.wikipedia.org/wiki/Bidirectional_map
>
> My seach into D documentation seem to said to me that this structure is
> not implemented.
>
> Something like (for primary idea):
>
>
> struct BidirectionalMap(T,U){
>      private:
>          T[U] _forwardHash;
>          U[T] _reverseHash;
>
>      public:
>
>          @safe
>          void opIndeyAssign( T k, U v){ // pure?
>              _forwardHash[k] = v;
>              _reverseHash[v] = k;
>          }
>
>
>          @property
>          BidirectionalMap!(T,U) dup(){
>              return BidirectionalMap!(T,U)( this );
>          }
> }

you could build one using multi_index.

https://bitbucket.org/ariovistus/multi_index

at least, that is how boost::bimap was done. I always assumed it would 
be trivial in D, but I haven't tried doing it. Something like

alias MultiIndexContainer!(Tuple!(T,"t",U,"u"), 
IndexedBy!(HashedUnique!("a.t"), HashedUnique!("a.u"))) BiMap;

and then wrap as you see fit.