[antlr-interest] Tree construction

[Haralambi Haralambiev]

Hello,

As far as I can understand - you do not have that '+' token on the left.

So, first, you should have an imaginary token defined in tokens{} block.

Then the following definition of the expr rule should do the work:
expr : (id expr) => id expr -> ^(PLUS id expr)
| id
;

Hope this helps.

-Hari

On 5/13/08, Ivan Yu Titov <ITitov at beeline.ru> wrote:
>
>
>       Hello,
>
>       I need to parse input "%a%b%c" into the tree. This tree should be
> like this (well-know example):
>
>        +
>       /  \
> %a     +
>            /  \
>      %b   %c
>
>       After lexer I have three tokens (%a, %b, %c). How can I apply to it
> following construction:
>
>       expr: id ('+'^ id)*;    ?
>
> Below is my grammar:
>
> grammar Expr;
>
> id
>       :     Reference
>       ;
>
> Reference
>       :     '%' Identifier
>       ;
>
> fragment
> Identifier
>       :     Letter (Letter | Digit | '_')*
>       ;
>
> fragment
> Letter      :     'a'..'z' | 'A'..'Z'
>       ;
>
> fragment
> Digit :     '0'..'9'
>       ;
>
>
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