[antlr-interest] Dumb question: combining all three grammars?

[Rick Mann]

Can I write a single grammar file that contains all three grammars (lexer, parser, tree)? The ANTLR book says,

	"Let’s build your first tree grammar in a separate file, which we’ll call Eval.g."

which I can interpret to imply "a later tree grammar will be built in the same file".

But, looking around, I see no way to do this.

TIA,
-- 
Rick