antlr/Antlr4.Runtime/Atn/ATNSimulator.cs

/*
 * [The "BSD license"]
 *  Copyright (c) 2013 Terence Parr
 *  Copyright (c) 2013 Sam Harwell
 *  All rights reserved.
 *
 *  Redistribution and use in source and binary forms, with or without
 *  modification, are permitted provided that the following conditions
 *  are met:
 *
 *  1. Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *  2. Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *  3. The name of the author may not be used to endorse or promote products
 *     derived from this software without specific prior written permission.
 *
 *  THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 *  IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 *  OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 *  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 *  INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 *  NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 *  DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 *  THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 *  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 *  THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
using System;
using System.Collections.Generic;
using System.IO;
using Antlr4.Runtime.Atn;
using Antlr4.Runtime.Dfa;
using Antlr4.Runtime.Misc;
using Sharpen;

namespace Antlr4.Runtime.Atn
{
	public abstract class ATNSimulator
	{
		public static readonly int SerializedVersion;

		static ATNSimulator()
		{
			SerializedVersion = 5;
		}

		public const char RuleVariantDelimiter = '$';

		public static readonly string RuleLfVariantMarker = "$lf$";

		public static readonly string RuleNolfVariantMarker = "$nolf$";

		/// <summary>Must distinguish between missing edge and edge we know leads nowhere</summary>
		[NotNull]
		public static readonly DFAState Error;

		[NotNull]
		public readonly ATN atn;

		static ATNSimulator()
		{
			Error = new DFAState(new ATNConfigSet(), 0, 0);
			Error.stateNumber = int.MaxValue;
		}

		public ATNSimulator(ATN atn)
		{
			this.atn = atn;
		}

		public abstract void Reset();

		public static ATN Deserialize(char[] data)
		{
			return Deserialize(data, true);
		}

		public static ATN Deserialize(char[] data, bool optimize)
		{
			data = data.Clone();
			// don't adjust the first value since that's the version number
			for (int i = 1; i < data.Length; i++)
			{
				data[i] = (char)(data[i] - 2);
			}
			ATN atn = new ATN();
			IList<IntervalSet> sets = new List<IntervalSet>();
			int p = 0;
			int version = ToInt(data[p++]);
			if (version != SerializedVersion)
			{
				string reason = string.Format("Could not deserialize ATN with version %d (expected %d)."
					, version, SerializedVersion);
				throw new NotSupportedException(new InvalidClassException(typeof(ATN).FullName, reason
					));
			}
			atn.grammarType = ToInt(data[p++]);
			atn.maxTokenType = ToInt(data[p++]);
			//
			// STATES
			//
			IList<Tuple<LoopEndState, int>> loopBackStateNumbers = new List<Tuple<LoopEndState
				, int>>();
			IList<Tuple<BlockStartState, int>> endStateNumbers = new List<Tuple<BlockStartState
				, int>>();
			int nstates = ToInt(data[p++]);
			for (int i_1 = 1; i_1 <= nstates; i_1++)
			{
				int stype = ToInt(data[p++]);
				// ignore bad type of states
				if (stype == ATNState.InvalidType)
				{
					atn.AddState(null);
					continue;
				}
				int ruleIndex = ToInt(data[p++]);
				ATNState s = StateFactory(stype, ruleIndex);
				if (stype == ATNState.LoopEnd)
				{
					// special case
					int loopBackStateNumber = ToInt(data[p++]);
					loopBackStateNumbers.AddItem(Tuple.Create((LoopEndState)s, loopBackStateNumber));
				}
				else
				{
					if (s is BlockStartState)
					{
						int endStateNumber = ToInt(data[p++]);
						endStateNumbers.AddItem(Tuple.Create((BlockStartState)s, endStateNumber));
					}
				}
				atn.AddState(s);
			}
			// delay the assignment of loop back and end states until we know all the state instances have been initialized
			foreach (Tuple<LoopEndState, int> pair in loopBackStateNumbers)
			{
				pair.GetItem1().loopBackState = atn.states[pair.GetItem2()];
			}
			foreach (Tuple<BlockStartState, int> pair_1 in endStateNumbers)
			{
				pair_1.GetItem1().endState = (BlockEndState)atn.states[pair_1.GetItem2()];
			}
			int numNonGreedyStates = ToInt(data[p++]);
			for (int i_2 = 0; i_2 < numNonGreedyStates; i_2++)
			{
				int stateNumber = ToInt(data[p++]);
				((DecisionState)atn.states[stateNumber]).nonGreedy = true;
			}
			int numSllDecisions = ToInt(data[p++]);
			for (int i_3 = 0; i_3 < numSllDecisions; i_3++)
			{
				int stateNumber = ToInt(data[p++]);
				((DecisionState)atn.states[stateNumber]).sll = true;
			}
			int numPrecedenceStates = ToInt(data[p++]);
			for (int i_4 = 0; i_4 < numPrecedenceStates; i_4++)
			{
				int stateNumber = ToInt(data[p++]);
				((RuleStartState)atn.states[stateNumber]).isPrecedenceRule = true;
			}
			//
			// RULES
			//
			int nrules = ToInt(data[p++]);
			if (atn.grammarType == ATN.Lexer)
			{
				atn.ruleToTokenType = new int[nrules];
				atn.ruleToActionIndex = new int[nrules];
			}
			atn.ruleToStartState = new RuleStartState[nrules];
			for (int i_5 = 0; i_5 < nrules; i_5++)
			{
				int s = ToInt(data[p++]);
				RuleStartState startState = (RuleStartState)atn.states[s];
				startState.leftFactored = ToInt(data[p++]) != 0;
				atn.ruleToStartState[i_5] = startState;
				if (atn.grammarType == ATN.Lexer)
				{
					int tokenType = ToInt(data[p++]);
					atn.ruleToTokenType[i_5] = tokenType;
					int actionIndex = ToInt(data[p++]);
					atn.ruleToActionIndex[i_5] = actionIndex;
				}
			}
			atn.ruleToStopState = new RuleStopState[nrules];
			foreach (ATNState state in atn.states)
			{
				if (!(state is RuleStopState))
				{
					continue;
				}
				RuleStopState stopState = (RuleStopState)state;
				atn.ruleToStopState[state.ruleIndex] = stopState;
				atn.ruleToStartState[state.ruleIndex].stopState = stopState;
			}
			//
			// MODES
			//
			int nmodes = ToInt(data[p++]);
			for (int i_6 = 0; i_6 < nmodes; i_6++)
			{
				int s = ToInt(data[p++]);
				atn.modeToStartState.AddItem((TokensStartState)atn.states[s]);
			}
			atn.modeToDFA = new DFA[nmodes];
			for (int i_7 = 0; i_7 < nmodes; i_7++)
			{
				atn.modeToDFA[i_7] = new DFA(atn.modeToStartState[i_7]);
			}
			//
			// SETS
			//
			int nsets = ToInt(data[p++]);
			for (int i_8 = 1; i_8 <= nsets; i_8++)
			{
				int nintervals = ToInt(data[p]);
				p++;
				IntervalSet set = new IntervalSet();
				sets.AddItem(set);
				for (int j = 1; j <= nintervals; j++)
				{
					set.Add(ToInt(data[p]), ToInt(data[p + 1]));
					p += 2;
				}
			}
			//
			// EDGES
			//
			int nedges = ToInt(data[p++]);
			for (int i_9 = 1; i_9 <= nedges; i_9++)
			{
				int src = ToInt(data[p]);
				int trg = ToInt(data[p + 1]);
				int ttype = ToInt(data[p + 2]);
				int arg1 = ToInt(data[p + 3]);
				int arg2 = ToInt(data[p + 4]);
				int arg3 = ToInt(data[p + 5]);
				Transition trans = EdgeFactory(atn, ttype, src, trg, arg1, arg2, arg3, sets);
				//			System.out.println("EDGE "+trans.getClass().getSimpleName()+" "+
				//							   src+"->"+trg+
				//					   " "+Transition.serializationNames[ttype]+
				//					   " "+arg1+","+arg2+","+arg3);
				ATNState srcState = atn.states[src];
				srcState.AddTransition(trans);
				p += 6;
			}
			// edges for rule stop states can be derived, so they aren't serialized
			foreach (ATNState state_1 in atn.states)
			{
				bool returningToLeftFactored = state_1.ruleIndex >= 0 && atn.ruleToStartState[state_1
					.ruleIndex].leftFactored;
				for (int i_10 = 0; i_10 < state_1.GetNumberOfTransitions(); i_10++)
				{
					Transition t = state_1.Transition(i_10);
					if (!(t is RuleTransition))
					{
						continue;
					}
					RuleTransition ruleTransition = (RuleTransition)t;
					bool returningFromLeftFactored = atn.ruleToStartState[ruleTransition.target.ruleIndex
						].leftFactored;
					if (!returningFromLeftFactored && returningToLeftFactored)
					{
						continue;
					}
					atn.ruleToStopState[ruleTransition.target.ruleIndex].AddTransition(new EpsilonTransition
						(ruleTransition.followState));
				}
			}
			foreach (ATNState state_2 in atn.states)
			{
				if (state_2 is BlockStartState)
				{
					// we need to know the end state to set its start state
					if (((BlockStartState)state_2).endState == null)
					{
						throw new InvalidOperationException();
					}
					// block end states can only be associated to a single block start state
					if (((BlockStartState)state_2).endState.startState != null)
					{
						throw new InvalidOperationException();
					}
					((BlockStartState)state_2).endState.startState = (BlockStartState)state_2;
				}
				if (state_2 is PlusLoopbackState)
				{
					PlusLoopbackState loopbackState = (PlusLoopbackState)state_2;
					for (int i_10 = 0; i_10 < loopbackState.GetNumberOfTransitions(); i_10++)
					{
						ATNState target = loopbackState.Transition(i_10).target;
						if (target is PlusBlockStartState)
						{
							((PlusBlockStartState)target).loopBackState = loopbackState;
						}
					}
				}
				else
				{
					if (state_2 is StarLoopbackState)
					{
						StarLoopbackState loopbackState = (StarLoopbackState)state_2;
						for (int i_10 = 0; i_10 < loopbackState.GetNumberOfTransitions(); i_10++)
						{
							ATNState target = loopbackState.Transition(i_10).target;
							if (target is StarLoopEntryState)
							{
								((StarLoopEntryState)target).loopBackState = loopbackState;
							}
						}
					}
				}
			}
			//
			// DECISIONS
			//
			int ndecisions = ToInt(data[p++]);
			for (int i_11 = 1; i_11 <= ndecisions; i_11++)
			{
				int s = ToInt(data[p++]);
				DecisionState decState = (DecisionState)atn.states[s];
				atn.decisionToState.AddItem(decState);
				decState.decision = i_11 - 1;
			}
			atn.decisionToDFA = new DFA[ndecisions];
			for (int i_12 = 0; i_12 < ndecisions; i_12++)
			{
				atn.decisionToDFA[i_12] = new DFA(atn.decisionToState[i_12], i_12);
			}
			if (optimize)
			{
				while (true)
				{
					int optimizationCount = 0;
					optimizationCount += InlineSetRules(atn);
					optimizationCount += CombineChainedEpsilons(atn);
					bool preserveOrder = atn.grammarType == ATN.Lexer;
					optimizationCount += OptimizeSets(atn, preserveOrder);
					if (optimizationCount == 0)
					{
						break;
					}
				}
			}
			IdentifyTailCalls(atn);
			VerifyATN(atn);
			return atn;
		}

		private static void VerifyATN(ATN atn)
		{
			// verify assumptions
			foreach (ATNState state in atn.states)
			{
				if (state == null)
				{
					continue;
				}
				CheckCondition(state.OnlyHasEpsilonTransitions() || state.GetNumberOfTransitions(
					) <= 1);
				if (state is PlusBlockStartState)
				{
					CheckCondition(((PlusBlockStartState)state).loopBackState != null);
				}
				if (state is StarLoopEntryState)
				{
					StarLoopEntryState starLoopEntryState = (StarLoopEntryState)state;
					CheckCondition(starLoopEntryState.loopBackState != null);
					CheckCondition(starLoopEntryState.GetNumberOfTransitions() == 2);
					if (starLoopEntryState.Transition(0).target is StarBlockStartState)
					{
						CheckCondition(starLoopEntryState.Transition(1).target is LoopEndState);
						CheckCondition(!starLoopEntryState.nonGreedy);
					}
					else
					{
						if (starLoopEntryState.Transition(0).target is LoopEndState)
						{
							CheckCondition(starLoopEntryState.Transition(1).target is StarBlockStartState);
							CheckCondition(starLoopEntryState.nonGreedy);
						}
						else
						{
							throw new InvalidOperationException();
						}
					}
				}
				if (state is StarLoopbackState)
				{
					CheckCondition(state.GetNumberOfTransitions() == 1);
					CheckCondition(state.Transition(0).target is StarLoopEntryState);
				}
				if (state is LoopEndState)
				{
					CheckCondition(((LoopEndState)state).loopBackState != null);
				}
				if (state is RuleStartState)
				{
					CheckCondition(((RuleStartState)state).stopState != null);
				}
				if (state is BlockStartState)
				{
					CheckCondition(((BlockStartState)state).endState != null);
				}
				if (state is BlockEndState)
				{
					CheckCondition(((BlockEndState)state).startState != null);
				}
				if (state is DecisionState)
				{
					DecisionState decisionState = (DecisionState)state;
					CheckCondition(decisionState.GetNumberOfTransitions() <= 1 || decisionState.decision
						 >= 0);
				}
				else
				{
					CheckCondition(state.GetNumberOfTransitions() <= 1 || state is RuleStopState);
				}
			}
		}

		public static void CheckCondition(bool condition)
		{
			CheckCondition(condition, null);
		}

		public static void CheckCondition(bool condition, string message)
		{
			if (!condition)
			{
				throw new InvalidOperationException(message);
			}
		}

		private static int InlineSetRules(ATN atn)
		{
			int inlinedCalls = 0;
			Transition[] ruleToInlineTransition = new Transition[atn.ruleToStartState.Length]
				;
			for (int i = 0; i < atn.ruleToStartState.Length; i++)
			{
				RuleStartState startState = atn.ruleToStartState[i];
				ATNState middleState = startState;
				while (middleState.OnlyHasEpsilonTransitions() && middleState.GetNumberOfOptimizedTransitions
					() == 1 && middleState.GetOptimizedTransition(0).SerializationType == Transition
					.Epsilon)
				{
					middleState = middleState.GetOptimizedTransition(0).target;
				}
				if (middleState.GetNumberOfOptimizedTransitions() != 1)
				{
					continue;
				}
				Transition matchTransition = middleState.GetOptimizedTransition(0);
				ATNState matchTarget = matchTransition.target;
				if (matchTransition.IsEpsilon || !matchTarget.OnlyHasEpsilonTransitions() || matchTarget
					.GetNumberOfOptimizedTransitions() != 1 || !(matchTarget.GetOptimizedTransition(
					0).target is RuleStopState))
				{
					continue;
				}
				switch (matchTransition.SerializationType)
				{
					case Transition.Atom:
					case Transition.Range:
					case Transition.Set:
					{
						ruleToInlineTransition[i] = matchTransition;
						break;
					}

					case Transition.NotSet:
					case Transition.Wildcard:
					{
						// not implemented yet
						continue;
						goto default;
					}

					default:
					{
						continue;
						break;
					}
				}
			}
			for (int stateNumber = 0; stateNumber < atn.states.Count; stateNumber++)
			{
				ATNState state = atn.states[stateNumber];
				if (state.ruleIndex < 0)
				{
					continue;
				}
				IList<Transition> optimizedTransitions = null;
				for (int i_1 = 0; i_1 < state.GetNumberOfOptimizedTransitions(); i_1++)
				{
					Transition transition = state.GetOptimizedTransition(i_1);
					if (!(transition is RuleTransition))
					{
						if (optimizedTransitions != null)
						{
							optimizedTransitions.AddItem(transition);
						}
						continue;
					}
					RuleTransition ruleTransition = (RuleTransition)transition;
					Transition effective = ruleToInlineTransition[ruleTransition.target.ruleIndex];
					if (effective == null)
					{
						if (optimizedTransitions != null)
						{
							optimizedTransitions.AddItem(transition);
						}
						continue;
					}
					if (optimizedTransitions == null)
					{
						optimizedTransitions = new List<Transition>();
						for (int j = 0; j < i_1; j++)
						{
							optimizedTransitions.AddItem(state.GetOptimizedTransition(i_1));
						}
					}
					inlinedCalls++;
					ATNState target = ruleTransition.followState;
					ATNState intermediateState = new BasicState();
					intermediateState.SetRuleIndex(target.ruleIndex);
					atn.AddState(intermediateState);
					optimizedTransitions.AddItem(new EpsilonTransition(intermediateState));
					switch (effective.SerializationType)
					{
						case Transition.Atom:
						{
							intermediateState.AddTransition(new AtomTransition(target, ((AtomTransition)effective
								).label));
							break;
						}

						case Transition.Range:
						{
							intermediateState.AddTransition(new RangeTransition(target, ((RangeTransition)effective
								).from, ((RangeTransition)effective).to));
							break;
						}

						case Transition.Set:
						{
							intermediateState.AddTransition(new SetTransition(target, effective.Label));
							break;
						}

						default:
						{
							throw new NotSupportedException();
						}
					}
				}
				if (optimizedTransitions != null)
				{
					if (state.IsOptimized())
					{
						while (state.GetNumberOfOptimizedTransitions() > 0)
						{
							state.RemoveOptimizedTransition(state.GetNumberOfOptimizedTransitions() - 1);
						}
					}
					foreach (Transition transition in optimizedTransitions)
					{
						state.AddOptimizedTransition(transition);
					}
				}
			}
			return inlinedCalls;
		}

		private static int CombineChainedEpsilons(ATN atn)
		{
			int removedEdges = 0;
			foreach (ATNState state in atn.states)
			{
				if (!state.OnlyHasEpsilonTransitions() || state is RuleStopState)
				{
					continue;
				}
				IList<Transition> optimizedTransitions = null;
				for (int i = 0; i < state.GetNumberOfOptimizedTransitions(); i++)
				{
					Transition transition = state.GetOptimizedTransition(i);
					ATNState intermediate = transition.target;
					if (transition.SerializationType != Transition.Epsilon || intermediate.GetStateType
						() != ATNState.Basic || !intermediate.OnlyHasEpsilonTransitions())
					{
						if (optimizedTransitions != null)
						{
							optimizedTransitions.AddItem(transition);
						}
						goto nextTransition_continue;
					}
					for (int j = 0; j < intermediate.GetNumberOfOptimizedTransitions(); j++)
					{
						if (intermediate.GetOptimizedTransition(j).SerializationType != Transition.Epsilon)
						{
							if (optimizedTransitions != null)
							{
								optimizedTransitions.AddItem(transition);
							}
							goto nextTransition_continue;
						}
					}
					removedEdges++;
					if (optimizedTransitions == null)
					{
						optimizedTransitions = new List<Transition>();
						for (int j_1 = 0; j_1 < i; j_1++)
						{
							optimizedTransitions.AddItem(state.GetOptimizedTransition(j_1));
						}
					}
					for (int j_2 = 0; j_2 < intermediate.GetNumberOfOptimizedTransitions(); j_2++)
					{
						ATNState target = intermediate.GetOptimizedTransition(j_2).target;
						optimizedTransitions.AddItem(new EpsilonTransition(target));
					}
nextTransition_continue: ;
				}
nextTransition_break: ;
				if (optimizedTransitions != null)
				{
					if (state.IsOptimized())
					{
						while (state.GetNumberOfOptimizedTransitions() > 0)
						{
							state.RemoveOptimizedTransition(state.GetNumberOfOptimizedTransitions() - 1);
						}
					}
					foreach (Transition transition in optimizedTransitions)
					{
						state.AddOptimizedTransition(transition);
					}
				}
			}
nextState_break: ;
			return removedEdges;
		}

		private static int OptimizeSets(ATN atn, bool preserveOrder)
		{
			if (preserveOrder)
			{
				// this optimization currently doesn't preserve edge order.
				return 0;
			}
			int removedPaths = 0;
			IList<DecisionState> decisions = atn.decisionToState;
			foreach (DecisionState decision in decisions)
			{
				IntervalSet setTransitions = new IntervalSet();
				for (int i = 0; i < decision.GetNumberOfOptimizedTransitions(); i++)
				{
					Transition epsTransition = decision.GetOptimizedTransition(i);
					if (!(epsTransition is EpsilonTransition))
					{
						continue;
					}
					if (epsTransition.target.GetNumberOfOptimizedTransitions() != 1)
					{
						continue;
					}
					Transition transition = epsTransition.target.GetOptimizedTransition(0);
					if (!(transition.target is BlockEndState))
					{
						continue;
					}
					if (transition is NotSetTransition)
					{
						// TODO: not yet implemented
						continue;
					}
					if (transition is AtomTransition || transition is RangeTransition || transition is
						 SetTransition)
					{
						setTransitions.Add(i);
					}
				}
				if (setTransitions.Size() <= 1)
				{
					continue;
				}
				IList<Transition> optimizedTransitions = new List<Transition>();
				for (int i_1 = 0; i_1 < decision.GetNumberOfOptimizedTransitions(); i_1++)
				{
					if (!setTransitions.Contains(i_1))
					{
						optimizedTransitions.AddItem(decision.GetOptimizedTransition(i_1));
					}
				}
				ATNState blockEndState = decision.GetOptimizedTransition(setTransitions.GetMinElement
					()).target.GetOptimizedTransition(0).target;
				IntervalSet matchSet = new IntervalSet();
				for (int i_2 = 0; i_2 < setTransitions.GetIntervals().Count; i_2++)
				{
					Interval interval = setTransitions.GetIntervals()[i_2];
					for (int j = interval.a; j <= interval.b; j++)
					{
						Transition matchTransition = decision.GetOptimizedTransition(j).target.GetOptimizedTransition
							(0);
						if (matchTransition is NotSetTransition)
						{
							throw new NotSupportedException("Not yet implemented.");
						}
						else
						{
							matchSet.AddAll(matchTransition.Label);
						}
					}
				}
				Transition newTransition;
				if (matchSet.GetIntervals().Count == 1)
				{
					if (matchSet.Size() == 1)
					{
						newTransition = new AtomTransition(blockEndState, matchSet.GetMinElement());
					}
					else
					{
						Interval matchInterval = matchSet.GetIntervals()[0];
						newTransition = new RangeTransition(blockEndState, matchInterval.a, matchInterval
							.b);
					}
				}
				else
				{
					newTransition = new SetTransition(blockEndState, matchSet);
				}
				ATNState setOptimizedState = new BasicState();
				setOptimizedState.SetRuleIndex(decision.ruleIndex);
				atn.AddState(setOptimizedState);
				setOptimizedState.AddTransition(newTransition);
				optimizedTransitions.AddItem(new EpsilonTransition(setOptimizedState));
				removedPaths += decision.GetNumberOfOptimizedTransitions() - optimizedTransitions
					.Count;
				if (decision.IsOptimized())
				{
					while (decision.GetNumberOfOptimizedTransitions() > 0)
					{
						decision.RemoveOptimizedTransition(decision.GetNumberOfOptimizedTransitions() - 1
							);
					}
				}
				foreach (Transition transition_1 in optimizedTransitions)
				{
					decision.AddOptimizedTransition(transition_1);
				}
			}
			return removedPaths;
		}

		private static void IdentifyTailCalls(ATN atn)
		{
			foreach (ATNState state in atn.states)
			{
				foreach (Transition transition in state.transitions)
				{
					if (!(transition is RuleTransition))
					{
						continue;
					}
					RuleTransition ruleTransition = (RuleTransition)transition;
					ruleTransition.tailCall = TestTailCall(atn, ruleTransition, false);
					ruleTransition.optimizedTailCall = TestTailCall(atn, ruleTransition, true);
				}
				if (!state.IsOptimized())
				{
					continue;
				}
				foreach (Transition transition_1 in state.optimizedTransitions)
				{
					if (!(transition_1 is RuleTransition))
					{
						continue;
					}
					RuleTransition ruleTransition = (RuleTransition)transition_1;
					ruleTransition.tailCall = TestTailCall(atn, ruleTransition, false);
					ruleTransition.optimizedTailCall = TestTailCall(atn, ruleTransition, true);
				}
			}
		}

		private static bool TestTailCall(ATN atn, RuleTransition transition, bool optimizedPath
			)
		{
			if (!optimizedPath && transition.tailCall)
			{
				return true;
			}
			if (optimizedPath && transition.optimizedTailCall)
			{
				return true;
			}
			BitSet reachable = new BitSet(atn.states.Count);
			IDeque<ATNState> worklist = new ArrayDeque<ATNState>();
			worklist.AddItem(transition.followState);
			while (!worklist.IsEmpty())
			{
				ATNState state = worklist.Pop();
				if (reachable.Get(state.stateNumber))
				{
					continue;
				}
				if (state is RuleStopState)
				{
					continue;
				}
				if (!state.OnlyHasEpsilonTransitions())
				{
					return false;
				}
				IList<Transition> transitions = optimizedPath ? state.optimizedTransitions : state
					.transitions;
				foreach (Transition t in transitions)
				{
					if (t.SerializationType != Transition.Epsilon)
					{
						return false;
					}
					worklist.AddItem(t.target);
				}
			}
			return true;
		}

		public static int ToInt(char c)
		{
			return c == 65535 ? -1 : c;
		}

		[NotNull]
		public static Transition EdgeFactory(ATN atn, int type, int src, int trg, int arg1
			, int arg2, int arg3, IList<IntervalSet> sets)
		{
			ATNState target = atn.states[trg];
			switch (type)
			{
				case Transition.Epsilon:
				{
					return new EpsilonTransition(target);
				}

				case Transition.Range:
				{
					return new RangeTransition(target, arg1, arg2);
				}

				case Transition.Rule:
				{
					RuleTransition rt = new RuleTransition((RuleStartState)atn.states[arg1], arg2, arg3
						, target);
					return rt;
				}

				case Transition.Predicate:
				{
					PredicateTransition pt = new PredicateTransition(target, arg1, arg2, arg3 != 0);
					return pt;
				}

				case Transition.Precedence:
				{
					return new PrecedencePredicateTransition(target, arg1);
				}

				case Transition.Atom:
				{
					return new AtomTransition(target, arg1);
				}

				case Transition.Action:
				{
					ActionTransition a = new ActionTransition(target, arg1, arg2, arg3 != 0);
					return a;
				}

				case Transition.Set:
				{
					return new SetTransition(target, sets[arg1]);
				}

				case Transition.NotSet:
				{
					return new NotSetTransition(target, sets[arg1]);
				}

				case Transition.Wildcard:
				{
					return new WildcardTransition(target);
				}
			}
			throw new ArgumentException("The specified transition type is not valid.");
		}

		public static ATNState StateFactory(int type, int ruleIndex)
		{
			ATNState s;
			switch (type)
			{
				case ATNState.InvalidType:
				{
					return null;
				}

				case ATNState.Basic:
				{
					s = new BasicState();
					break;
				}

				case ATNState.RuleStart:
				{
					s = new RuleStartState();
					break;
				}

				case ATNState.BlockStart:
				{
					s = new BasicBlockStartState();
					break;
				}

				case ATNState.PlusBlockStart:
				{
					s = new PlusBlockStartState();
					break;
				}

				case ATNState.StarBlockStart:
				{
					s = new StarBlockStartState();
					break;
				}

				case ATNState.TokenStart:
				{
					s = new TokensStartState();
					break;
				}

				case ATNState.RuleStop:
				{
					s = new RuleStopState();
					break;
				}

				case ATNState.BlockEnd:
				{
					s = new BlockEndState();
					break;
				}

				case ATNState.StarLoopBack:
				{
					s = new StarLoopbackState();
					break;
				}

				case ATNState.StarLoopEntry:
				{
					s = new StarLoopEntryState();
					break;
				}

				case ATNState.PlusLoopBack:
				{
					s = new PlusLoopbackState();
					break;
				}

				case ATNState.LoopEnd:
				{
					s = new LoopEndState();
					break;
				}

				default:
				{
					string message = string.Format("The specified state type %d is not valid.", type);
					throw new ArgumentException(message);
				}
			}
			s.ruleIndex = ruleIndex;
			return s;
		}
	}
}