Create a bridge pattern to decouple Builder calls from the parser

[rajatkb]

The parser logic should only be focused on the language an not on the builder. So we need a separate adapter class that can make the calls for the parsed content. This will decouple the knowledge of the builder from the parser. Allowing someone to change the builder mechanism in the backend irrespective of the changes in the language or vice versa.

// So it would be somewhat like this

streamToken.scanleft( list('S' , '$') )(  (stack, token) => action(stack  , adapter(builder)) )

// where adapter abstracts the builde calls
// so that in future

streamToken.scanleft( list('S' , '$') )(  (stack, token) => action(stack  , adapter(newBuilder)) )

// will remain the same. The call pattern and what point call to builder will be made will be determined by the adapter. So changes will be localised to adapter to accept chainging in Builder.
// No body wants to touch the parser.