ParserATNSimulator.execATN

There are some key conditions we're looking for after computing a new set of ATN configs (proposed DFA state): <br>- if the set is empty, there is no viable alternative for current symbol <br>- does the state uniquely predict an alternative? <br>- does the state have a conflict that would prevent us from putting it on the work list? <br><br>We also have some key operations to do: <br>- add an edge from previous DFA state to potentially new DFA state, D, upon current symbol but only if adding to work list, which means in all cases except no viable alternative (and possibly non-greedy decisions?) <br>- collecting predicates and adding semantic context to DFA accept states <br>- adding rule context to context-sensitive DFA accept states <br>- consuming an input symbol <br>- reporting a conflict <br>- reporting an ambiguity <br>- reporting a context sensitivity <br>- reporting insufficient predicates <br><br>cover these cases: <br>- dead end <br>- single alt <br>- single alt + preds <br>- conflict <br>- conflict + preds