Examine an expression tree, looking for molecule expressions.
Examine an expression tree, looking for molecule expressions.
An expression tree (could be the "case" pattern, the "if" guard, or the reaction body).
A 4-tuple: List of input molecule patterns, list of output molecule patterns, list of reply action patterns, and list of molecules erroneously used inside pattern matching expressions.
This is the main traverser that gathers information about molecule inputs and outputs in a reaction.