CSharp listener example rather incomplete

[Michael Powell]

Hello,

The example is a good start getting one's feet wet with the parser listener issue.

However, I do not think it goes quite far enough.

https://github.com/antlr/antlr4/blob/master/doc/csharp-target.md#how-do-i-create-and-run-a-custom-listener

The rub is really this:

class KeyPrinter : MyGrammarBaseListener {
    // override default listener behavior
    void ExitKey (MyGrammarParser.KeyContext context) {
        Console.WriteLine("Oh, a key!");
    }
}

Here, we marvel that we have a MyGrammarParser.KeyContext. However, great, so what? What do we do with the actual Context? This doesn't even attempt to scratch the Context surface. How do we get to the bits behind the Context to do anything useful with that? In my case, I'd like to round out an AST for internal use after visiting each node.

Best regards,

Michael W Powell