Re: Computing FIRST(X) for a left recursive grammar

By response is based upon material in chapter 4 of the book
"Compilers Principles, Techniques and tools". This book is often called
the dragon book. I would advise that you obtain access to this book.


Now here is FIRST(list):
FIRST(list) = { epsilon, NEWLINE, FIRST(expr) }


We include epsilon because list goes to epsilon.
We include FIRST(expr) because list can reduce to epsilon.


Alessandro Muzzetta wrote:
>
> Hello,
>
> can some kind soul please answer this silly question of mine...
>
> Assuming you have the following yacc rules
>
> list: /* empty */
> | list NEWLINE
> | list expr NEWLINE
> ;
> expr: ...
> ;
>
> How do I calculate FIRST(list) for this left recursive grammar?

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