Antlr3.Tool.ErrorManager.GrammarWarning C# (CSharp) Method

        public static void GrammarWarning( int msgID,
                                          Grammar g,
                                          IToken token )
        {
            GrammarWarning( msgID, g, token, null, null );
        }

        /** Rules in tree grammar that use -> rewrites and are spitting out
         *  templates via output=template and then use rewrite=true must only
         *  use -> on alts that are simple nodes or trees or single rule refs
         *  that match either nodes or trees.  The altAST is the ALT node
         *  for an ALT.  Verify that its first child is simple.  Must be either
         *  ( ALT ^( A B ) <end-of-alt> ) or ( ALT A <end-of-alt> ) or
         *  other element.
         *
         *  Ignore predicates in front and labels.
         */
        public virtual void EnsureAltIsSimpleNodeOrTree(GrammarAST altAST,
                                                        GrammarAST elementAST,
                                                        int outerAltNum)
        {
            if (IsValidSimpleElementNode(elementAST))
            {
                GrammarAST next = (GrammarAST)elementAST.Parent.GetChild(elementAST.ChildIndex + 1);
                if (!IsNextNonActionElementEOA(next))
                {
                    ErrorManager.GrammarWarning(ErrorManager.MSG_REWRITE_FOR_MULTI_ELEMENT_ALT,
                                                grammar,
                                                next.Token,
                                                outerAltNum);
                }
                return;
            }
            switch (elementAST.Type)
            {
            case ANTLRParser.ASSIGN:            // labels ok on non-rule refs
            case ANTLRParser.PLUS_ASSIGN:
                if (IsValidSimpleElementNode((GrammarAST)elementAST.GetChild(1)))
                {
                    return;
                }
                break;

            case ANTLRParser.ACTION:            // skip past actions
            case ANTLRParser.SEMPRED:
            case ANTLRParser.SYN_SEMPRED:
            case ANTLRParser.BACKTRACK_SEMPRED:
            case ANTLRParser.GATED_SEMPRED:
                EnsureAltIsSimpleNodeOrTree(altAST,
                                            (GrammarAST)elementAST.Parent.GetChild(elementAST.ChildIndex + 1),
                                            outerAltNum);
                return;
            }
            ErrorManager.GrammarWarning(ErrorManager.MSG_REWRITE_FOR_MULTI_ELEMENT_ALT,
                                        grammar,
                                        elementAST.Token,
                                        outerAltNum);
        }