Antlr4.Semantics.BasicSemanticChecks.FinishRule C# (CSharp) Method

        public override void FinishRule(RuleAST rule, GrammarAST ID, GrammarAST block)
        {
            if (rule.IsLexerRule())
                return;
            BlockAST blk = (BlockAST)rule.GetFirstChildWithType(BLOCK);
            int nalts = blk.ChildCount;
            GrammarAST idAST = (GrammarAST)rule.GetChild(0);
            for (int i = 0; i < nalts; i++)
            {
                AltAST altAST = (AltAST)blk.GetChild(i);
                if (altAST.altLabel != null)
                {
                    string altLabel = altAST.altLabel.Text;
                    // first check that label doesn't conflict with a rule
                    // label X or x can't be rule x.
                    Rule r;
                    if (ruleCollector.rules.TryGetValue(Utils.Decapitalize(altLabel), out r) && r != null)
                    {
                        g.tool.errMgr.GrammarError(ErrorType.ALT_LABEL_CONFLICTS_WITH_RULE,
                                                   g.fileName, altAST.altLabel.Token,
                                                   altLabel,
                                                   r.name);
                    }
                    // Now verify that label X or x doesn't conflict with label
                    // in another rule. altLabelToRuleName has both X and x mapped.
                    string prevRuleForLabel;
                    if (ruleCollector.altLabelToRuleName.TryGetValue(altLabel, out prevRuleForLabel) && prevRuleForLabel != null && !prevRuleForLabel.Equals(rule.GetRuleName()))
                    {
                        g.tool.errMgr.GrammarError(ErrorType.ALT_LABEL_REDEF,
                                                   g.fileName, altAST.altLabel.Token,
                                                   altLabel,
                                                   rule.GetRuleName(),
                                                   prevRuleForLabel);
                    }
                }
            }
            IList<GrammarAST> altLabels;
            int numAltLabels = 0;
            if (ruleCollector.ruleToAltLabels.TryGetValue(rule.GetRuleName(), out altLabels) && altLabels != null)
                numAltLabels = altLabels.Count;
            if (numAltLabels > 0 && nalts != numAltLabels)
            {
                g.tool.errMgr.GrammarError(ErrorType.RULE_WITH_TOO_FEW_ALT_LABELS,
                                           g.fileName, idAST.Token, rule.GetRuleName());
            }
        }