Antlr4.Automata.ATNOptimizer.Optimize C# (CSharp) Method

        public static void Optimize([NotNull] Grammar g, [NotNull] ATN atn)
        {
            OptimizeSets(g, atn);
            OptimizeStates(atn);
        }

        public virtual ATN CreateATN()
        {
            _CreateATN(g.rules.Values);

            Debug.Assert(atn.maxTokenType == g.GetMaxTokenType());
            AddRuleFollowLinks();
            AddEOFTransitionToStartRules();
            ATNOptimizer.Optimize(g, atn);

            foreach (System.Tuple <Rule, ATNState, ATNState> pair in preventEpsilonClosureBlocks)
            {
                LL1Analyzer analyzer  = new LL1Analyzer(atn);
                ATNState    blkStart  = pair.Item2;
                ATNState    blkStop   = pair.Item3;
                IntervalSet lookahead = analyzer.Look(blkStart, blkStop, PredictionContext.EmptyLocal);
                if (lookahead.Contains(Antlr4.Runtime.TokenConstants.Epsilon))
                {
                    ErrorType errorType = pair.Item1 is LeftRecursiveRule ? ErrorType.EPSILON_LR_FOLLOW : ErrorType.EPSILON_CLOSURE;
                    g.tool.errMgr.GrammarError(errorType, g.fileName, ((GrammarAST)pair.Item1.ast.GetChild(0)).Token, pair.Item1.name);
                }
            }

            foreach (System.Tuple <Rule, ATNState, ATNState> pair in preventEpsilonOptionalBlocks)
            {
                int bypassCount = 0;
                for (int i = 0; i < pair.Item2.NumberOfTransitions; i++)
                {
                    ATNState startState = pair.Item2.Transition(i).target;
                    if (startState == pair.Item3)
                    {
                        bypassCount++;
                        continue;
                    }

                    LL1Analyzer analyzer = new LL1Analyzer(atn);
                    if (analyzer.Look(startState, pair.Item3, PredictionContext.EmptyLocal).Contains(Antlr4.Runtime.TokenConstants.Epsilon))
                    {
                        g.tool.errMgr.GrammarError(ErrorType.EPSILON_OPTIONAL, g.fileName, ((GrammarAST)pair.Item1.ast.GetChild(0)).Token, pair.Item1.name);
                        goto continueOptionalCheck;
                    }
                }

                if (bypassCount != 1)
                {
                    throw new InvalidOperationException("Expected optional block with exactly 1 bypass alternative.");
                }

continueOptionalCheck:
                ;
            }

            return(atn);
        }