[antlr-interest] Re: unexpected AST node

[Bryan Ewbank]

The problem is in your main program - you are calling the tree parser
three times for the input, and only the first call can accept a "+"
node.  The other calls fail because the root node of the tree is "+".

For logical not, "!", the trick is to use right-recursion:

    not_expr
        : NOT^ not_expr
        | bexpr
        ;

This will form the necessary tree for correct evaluation

On 2/28/06, Zara Jane Sheil <zara.sheil at ucdconnect.ie> wrote:
> Also, when I give it input 3+4 it can return the value 7 but gives an error:
>   <AST>:0:0: unexpected AST node: +
>   false
>   <AST>:0:0: unexpected AST node: +
>   false
> This happens for all input. Im not sure if there's something wrong with the
> grammar or my Main file.