[antlr-interest] How does AST construction work?

[Paul Johnson]

[I originally posted this about 15 hours ago, but it hasn't yet appeared 
on the list... giving it another go]

Thanks - I think the fog is slowly lifting...

Bryan Ewbank wrote:
> Try removing the "^" from your example and look at the results.  This
> should help...

I tried this, and the returned tree just contains '2':

expr : mexpr (PLUS mexpr)* SEMI! ;

mexpr : atom (STAR atom)* ;

-----
> Main
> 2+4*5;
  2
value is 2
-----

At first sight, it seems to me that the returned list should actually
have been ( 2 + 4 * 5 ) (with no root - or does the first parsed element
become the root by default?)

My reasoning is simply that the first call to mexpr returns the list
(2), then PLUS is appended, and the second call to mexpr returns the
list (4 STAR 5). How is it that just a single '2' is returned?

Thanks -

Paul