Antlr4.Runtime.Atn.ParserATNSimulator.PredTransition C# (CSharp) Метод

        protected ATNConfig PredTransition(ATNConfig config,
										PredicateTransition pt,
										bool collectPredicates,
										bool inContext,
										bool fullCtx)
        {
            if (debug)
            {
                Console.WriteLine("PRED (collectPredicates=" + collectPredicates + ") " +
                        pt.ruleIndex + ":" + pt.predIndex +
                        ", ctx dependent=" + pt.isCtxDependent);
                if (parser != null)
                {
                    Console.WriteLine("context surrounding pred is " +
                                       parser.GetRuleInvocationStack());
                }
            }

            ATNConfig c = null;
            if (collectPredicates &&
                 (!pt.isCtxDependent || (pt.isCtxDependent && inContext)))
            {
                if (fullCtx)
                {
                    // In full context mode, we can evaluate predicates on-the-fly
                    // during closure, which dramatically reduces the size of
                    // the config sets. It also obviates the need to test predicates
                    // later during conflict resolution.
                    int currentPosition = input.Index;
                    input.Seek(startIndex);
                    bool predSucceeds = EvalSemanticContext(pt.Predicate, context, config.alt, fullCtx);
                    input.Seek(currentPosition);
                    if (predSucceeds)
                    {
                        c = new ATNConfig(config, pt.target); // no pred context
                    }
                }
                else {
                    SemanticContext newSemCtx = SemanticContext.AndOp(config.semanticContext, pt.Predicate);
                    c = new ATNConfig(config, pt.target, newSemCtx);
                }
            }
            else {
                c = new ATNConfig(config, pt.target);
            }

            if (debug) Console.WriteLine("config from pred transition=" + c);
            return c;
        }