Hi Michael,

Thanks for the response.  I've put together a sample project which will hopefully show you what exactly I'm trying to accomplish.  

I'm trying to show invalid match when "LASTRUN" (has to be inside % signs) does not exactly match the word LASTRUN(whitespace before or after % signs should be invalid - see Doesn't work! in picture below).  The regular expression I'm testing that works  ->  ^(LASTRUN)$  cannot be used in the code snippet out of my sample project below:

           var daVarContent = lexerState.Symbols.Add("DaVarContent", @"(LASTRUN)", TerminalSymbolComparison.RegularExpression);
            daVarContent.LanguageElementName = languageElementName;
            //daVarContent.LookaheadPattern = @"[^\S]";
            //daVarContent.IsLookaheadNegative = true;

So, the main portion of the sample I'd like for you to take a look at is inside this method - 

public void DAVariableLanguage2(Grammar grammar).  Maybe there is a way to accomplish what I am trying to do by using a LookaheadPattern.  I've done a lot of experimentation but haven't been able to make this work.  

Hello Andy, 

Hey Michael,

Thanks for following up.  After more experimentation, we have come up with a solution, but have found another problem in the process.

The following code is working exactly how we would like it to:

NonTerminalSymbol identifierResolved;
            if (grammar.NonTerminalSymbols.TryGetSymbol("_identifierResolved", out identifierResolved) == false)
            {
                Debug.Fail("Cannot find the _identifierResolved symbol.");
                return null;
            }

            var alternateRule = identifierResolved.Rule as AlternationSyntaxRule;
            if (alternateRule == null)
            {
                Debug.Fail("The _identifierResolved symbol does not have an alternation at the root level rule, as expected.");
                return null;
            }

            #endregion

            var defaultLexerState = grammar.LexerStates.DefaultLexerState;
            var languageName = "Custom";
            int j = 0;

            // Not sure of exactly how many of these cause an out of memory exception, but 750 will definitely cause the
            // out of memory exception

            JobVariables.ForEach(var =>
            {
                var validVar = defaultLexerState.Symbols.Insert(0, "ValidVar" + j++.ToString(), "%" + var + "%", TerminalSymbolComparison.LiteralIgnoreCase);
                validVar.LanguageElementName = languageName;
                alternateRule.Rules.Add(validVar);
            });

            if (ClassificationAppearanceMap == null)
                ClassificationAppearanceMap = new ClassificationAppearanceMap();

            ClassificationAppearanceMap.AddMapEntry(
                new ClassificationType(languageName, languageName, "The keyword for the Custom name"),
                new TextDocumentAppearance() { Foreground = new SolidColorBrush(Colors.DarkOrange), FontBold = true });

            return grammar;

Only issue with this code is if we add 750 or more ("defaultLexerState.Symbols"), we get an out of memory exception.  The attached sample project is set up to display the issue.  Please review and let me know what you think.  

Thanks

Andy