Antlr.Runtime.BaseRecognizer.MismatchIsMissingToken C# (CSharp) Method

        public virtual bool MismatchIsMissingToken( IIntStream input, BitSet follow )
        {
            if ( follow == null )
            {
                // we have no information about the follow; we can only consume
                // a single token and hope for the best
                return false;
            }
            // compute what can follow this grammar element reference
            if ( follow.Member( TokenTypes.EndOfRule ) )
            {
                BitSet viableTokensFollowingThisRule = ComputeContextSensitiveRuleFOLLOW();
                follow = follow.Or( viableTokensFollowingThisRule );
                if ( state._fsp >= 0 )
                { // remove EOR if we're not the start symbol
                    follow.Remove( TokenTypes.EndOfRule );
                }
            }
            // if current token is consistent with what could come after set
            // then we know we're missing a token; error recovery is free to
            // "insert" the missing token

            //System.out.println("viable tokens="+follow.toString(getTokenNames()));
            //System.out.println("LT(1)="+((TokenStream)input).LT(1));

            // BitSet cannot handle negative numbers like -1 (EOF) so I leave EOR
            // in follow set to indicate that the fall of the start symbol is
            // in the set (EOF can follow).
            if ( follow.Member( input.LA( 1 ) ) || follow.Member( TokenTypes.EndOfRule ) )
            {
                //System.out.println("LT(1)=="+((TokenStream)input).LT(1)+" is consistent with what follows; inserting...");
                return true;
            }
            return false;
        }