Using C# and gppg, how would I construct an abstract syntax tree?

Question

Is there a way to do this almost out-of-the-box?

I could go and write a big method that would use the collected tokens to figure out which leaves should be put in which branches and in the end populate a TreeNode object, but since gppg already handled everything by using supplied regular expressions, I was wondering if there's an easier way? Even if not, any pointers as to how best to approach the problem of creating an AST would be appreciated.

Apologies if I said anything silly, I'm only just beginning to play the compiler game. :)

Answer 1

See MGrammar and Oslo...

http://msdn.microsoft.com/oslo

http://channel9.msdn.com/pdc2008/TL31/

Answer 2

Take a look at ANTLR, I did a simple .NET compiler written in C# with it few years back.

Answer 3

1. In your syntax file declare a property which will keep the root of your AST:

   %{ public BatchNode Batch; public ErrorHandler yyhldr; private TransformationContext _txContext = TransformationContext.Instance; %}

2. Start writing your grammar with actions which build nodes of your AST:

   Batch : StatementList {Batch = new BatchNode($1.Statements);} ;

   StatementList : Statement {$$.Statements = new List(); $$.Statements.Add($1.Statement); } | StatementList Statement {$$.Statements = $1.Statements; $$.Statements.Add($2.Statement);} ;

3. Call parser:

           var parser = new Parser.Parser();
           var scanner = new Scanner();
           parser.scanner = scanner;
           scanner.SetSource(sourceString, 0);
           bool result = parser.Parse();
           if (!result)
           {
   
   
       }