[antlr-interest] How to define multi and div?

[=?GB2312?B?0MLC8g==?=]

I see.same structure must in a rule...

Now it works OK.

Thank u very much.


2005/12/11, Bryan Ewbank <ewbank at gmail.com>:
>
> It cannot be *split*, because of the ambiguity.  It can be joined into
> one rule, though.  Since MULTI and DIV are at the same precedence
> level, you need to build the grammar to accept either one:
>
>    mulitdivExpr
>        :  parenExpr ( ( MULTI^ | DIV^ ) parenExpr )* ;
>
> This says to match a parenExpr, with zero or more following MULTI or
> DIV operation.  Perhaps it's easier to see if it's written this
> (equivalent) way:
>
>    mulitdivExpr
>        :  parenExpr                    // A
>            ( MULTI^ parenExpr          // * B
>            | DIV^ parenExpr            // / B
>            )*
>        ;
>
> Hope this helps,
> - Bryan
>
> On 12/10/05, °p <inshua at gmail.com> wrote:
> > I 'd found this way in samples ,it did not define MULTI and DIV but
> define
> >
> > MULTI_DIV : * | /
> >
> > but in this way , the multi expr and div expr cannot be recognized in
> the
> > parser, in the following step, I should test the text of the AST node to
> > decide how to run the whole expression.
> >
> > A same rule cannot be split ?
>
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