Re: shift/reduce and reduce/reduce conflicts

[wim delvaux]

On Friday 23 January 2004 18:52, Valter G. Nogueira Jr. wrote:
> I am developing a Visual Basic parser and since it was my first
> non-tutorial based work I was pretty happy about it.
>
> Since I was unaware of option -v I have got a mess of conflicts.
>
> Now, I have hundreds of conflicts which I have to purge out my code.
>
> I what make me asthonised gcc-java(v3.3.2)'s parse.y has NONE conflicts.
>
> Is that normal?

        Normal ... well let's say preferrable

>
> Does have any tips about vanishing these conflicts away?

        Conflicts occur when your parser cannot determine the next move to take 
in a 
presice manner

        example

        a : Token1 Token2
           | Token1 Token3
        ;

        when the scanner finds token1 what comes next a 2 or 3 token ?  Answer 
: it 
depends on the input syntax.  Bison does not like these situations.  For each 
token scanned, bison should be able to exactly determine the next state.

        Solution : RTFM : there is a better description of these conflicts.
        Solution 2 : produce the special output file (see -r) and check what 
problems 
there are
>
> May I run bison on a file without type checks and actions just to check the
> grammar (right before to put C code in it)?

        sure ... it will do nothing just check for the first syntax error.

>
> Thanks
>
> Valter