private void AddSymbolsToProduction(Production prod, List <string> list)
        {
            // Version 1.3.1 sends even empty lists to this method.
            // Furthermore, version 1.3.1 no longer explicitly calls
            // FixInternalReduction().  It is easier to adopt a consistent
            // approach and let AddXxxToProd check for a trailing action
            // prior to adding symbols or a new action.
            //
            if (list != null)
            {
                if (prod.semanticAction != null || prod.precSpan != null)
                {
                    FixInternalReduction(prod);
                }
                foreach (string str in list)
                {
                    Symbol symbol = null;

                    switch (TokenOf(str))
                    {
                    case Token.litchar:     // This is a character literal symbol
                        if (GPCG.ImportedTokens && Terminal.BumpsMax(str))
                        {
                            handler.ListError(this.CurrentLocationSpan, 82, str, '\0');
                        }
                        symbol = grammar.LookupTerminal(Token.litchar, str);
                        break;

                    case Token.litstring:     // This is a uned occurrence of a terminal alias.
                        String s = CharacterUtilities.CanonicalizeAlias(str);
                        if (!grammar.aliasTerms.ContainsKey(s))
                        {
                            handler.ListError(this.CurrentLocationSpan, 83, str, '\0');
                        }
                        else
                        {
                            symbol = grammar.aliasTerms[s];
                            if (symbol == Terminal.Ambiguous)     // Use of an ambiguous alias.
                            {
                                handler.ListError(this.CurrentLocationSpan, 84, str, '\0');
                            }
                        }
                        break;

                    case Token.ident:     // This is a used occurrence of a terminal name.
                        if (grammar.terminals.ContainsKey(str))
                        {
                            symbol = grammar.terminals[str];
                        }
                        else
                        {
                            symbol = grammar.LookupNonTerminal(str);
                        }
                        break;
                    }
                    prod.rhs.Add(symbol);
                }
            }
        }