Antlr4.Analysis.LeftRecursiveRuleTransformer.TranslateLeftRecursiveRules C# (CSharp) Method

        public virtual void TranslateLeftRecursiveRules()
        {
            string language = g.GetOptionString("language");
            // translate all recursive rules
            IList<string> leftRecursiveRuleNames = new List<string>();
            foreach (Rule r in rules)
            {
                if (!Grammar.IsTokenName(r.name))
                {
                    if (LeftRecursiveRuleAnalyzer.HasImmediateRecursiveRuleRefs(r.ast, r.name))
                    {
                        bool fitsPattern = TranslateLeftRecursiveRule(ast, (LeftRecursiveRule)r, language);
                        if (fitsPattern)
                        {
                            leftRecursiveRuleNames.Add(r.name);
                        }
                        else
                        {
                            // Suppressed since this build has secondary support for left recursive rules that don't
                            // match the patterns for precedence rules.

                            // better given an error that non-conforming left-recursion exists
                            //tool.errMgr.grammarError(ErrorType.NONCONFORMING_LR_RULE, g.fileName, ((GrammarAST)r.ast.GetChild(0)).Token, r.name);
                        }
                    }
                }
            }

            // update all refs to recursive rules to have [0] argument
            foreach (GrammarAST r in ast.GetNodesWithType(ANTLRParser.RULE_REF))
            {
                if (r.Parent.Type == ANTLRParser.RULE)
                    continue; // must be rule def
                if (((GrammarASTWithOptions)r).GetOptionString(PRECEDENCE_OPTION_NAME) != null)
                    continue; // already has arg; must be in rewritten rule
                if (leftRecursiveRuleNames.Contains(r.Text))
                {
                    // found ref to recursive rule not already rewritten with arg
                    ((GrammarASTWithOptions)r).SetOption(PRECEDENCE_OPTION_NAME, (GrammarAST)new GrammarASTAdaptor().Create(ANTLRParser.INT, "0"));
                }
            }
        }

        public virtual void Process()
        {
            if (g.ast == null)
                return;

            // COLLECT RULE OBJECTS
            RuleCollector ruleCollector = new RuleCollector(g);
            ruleCollector.Process(g.ast);

            // CLONE RULE ASTs FOR CONTEXT REFERENCE
            foreach (Rule rule in ruleCollector.rules.Values)
            {
                IList<RuleAST> list;
                if (!g.contextASTs.TryGetValue(rule.GetBaseContext(), out list) || list == null)
                {
                    list = new List<RuleAST>();
                    g.contextASTs[rule.GetBaseContext()] = list;
                }

                list.Add((RuleAST)rule.ast.DupTree());
            }

            // DO BASIC / EASY SEMANTIC CHECKS
            int prevErrors = g.tool.errMgr.GetNumErrors();
            BasicSemanticChecks basics = new BasicSemanticChecks(g, ruleCollector);
            basics.Process();
            if (g.tool.errMgr.GetNumErrors() > prevErrors)
                return;

            // TRANSFORM LEFT-RECURSIVE RULES
            prevErrors = g.tool.errMgr.GetNumErrors();
            LeftRecursiveRuleTransformer lrtrans =
                new LeftRecursiveRuleTransformer(g.ast, ruleCollector.rules.Values, g);
            lrtrans.TranslateLeftRecursiveRules();

            // don't continue if we got errors during left-recursion elimination
            if (g.tool.errMgr.GetNumErrors() > prevErrors)
            {
                return;
            }

            // AUTO LEFT FACTORING
            LeftFactoringRuleTransformer lftrans = new LeftFactoringRuleTransformer(g.ast, ruleCollector.rules, g);
            lftrans.TranslateLeftFactoredRules();

            // STORE RULES IN GRAMMAR
            foreach (Rule r in ruleCollector.rules.Values)
            {
                g.DefineRule(r);
            }

            // COLLECT SYMBOLS: RULES, ACTIONS, TERMINALS, ...
            SymbolCollector collector = new SymbolCollector(g);
            collector.Process(g.ast);

            // CHECK FOR SYMBOL COLLISIONS
            SymbolChecks symcheck = new SymbolChecks(g, collector);
            symcheck.Process(); // side-effect: strip away redef'd rules.

            foreach (GrammarAST a in collector.namedActions)
            {
                g.DefineAction(a);
            }

            // LINK (outermost) ALT NODES WITH Alternatives
            foreach (Rule r in g.rules.Values)
            {
                for (int i = 1; i <= r.numberOfAlts; i++)
                {
                    r.alt[i].ast.alt = r.alt[i];
                }
            }

            // ASSIGN TOKEN TYPES
            g.ImportTokensFromTokensFile();
            if (g.IsLexer())
            {
                AssignLexerTokenTypes(g, collector.tokensDefs);
            }
            else
            {
                AssignTokenTypes(g, collector.tokensDefs,
                                 collector.tokenIDRefs, collector.terminals);
            }

            symcheck.CheckForModeConflicts(g);

            AssignChannelTypes(g, collector.channelDefs);

            // CHECK RULE REFS NOW (that we've defined rules in grammar)
            symcheck.CheckRuleArgs(g, collector.rulerefs);
            IdentifyStartRules(collector);
            symcheck.CheckForQualifiedRuleIssues(g, collector.qualifiedRulerefs);

            // don't continue if we got symbol errors
            if (g.tool.GetNumErrors() > 0)
                return;

            // CHECK ATTRIBUTE EXPRESSIONS FOR SEMANTIC VALIDITY
            AttributeChecks.CheckAllAttributeExpressions(g);

            UseDefAnalyzer.TrackTokenRuleRefsInActions(g);
        }