[antlr-interest] Change operator precedence in a AST

Joan Pujol joanpujol at gmail.com
Sun Sep 26 14:37:12 PDT 2004

On Sun, 26 Sep 2004 16:38:02 -0400, Bryan Ewbank <ewbank at synopsys.com> wrote:
> Joan Jesús said:
> > How can I change the precedence of operator of my AST
> > to reflect the operator precedence in  Java.
> > Someone has some example?
> I'm puzzled.  In an AST there isn't really precedence - you just evaluate
> bottom-up.  Are you looking for guidance in rewriting/rotate the trees to
> reflect a change in precedence?  E.g, something like this?
> Given:
>         (+ A (* C D))
> Produce:
>         (* (+ A C) D)
Yes, exactly.

The problem is that I generate the AST using the operator's precedence
of my language. But then when I want to use the AST to translate to
the target language I can't use my AST directly to output code because
the priority of operators change. And I don't know how to manage this
Joan Jesús Pujol Espinar

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