Re: Interactive parsing with Bison

[Akim Demaille]

Le 8 juil. 06 à 03:13, Richard Stallman a écrit :

>     Bison currently uses M4 to process parser skeletons before  
> outputting
>     them.  Formerly this processing was done by hand in C code, in  
> Bison,
>     but this was painful to maintain as we added more  
> functionality.  M4
>     is slow, and scales poorly, but we didn't think efficiency during
>     parser generation was all that important,
>
> Is GNU M4 slower than it ought to be?

GNU M4 is quite fast for an M4, but with more builtins, several
constructs could be made much faster.  As a matter of fact, I think
the impact is very barable with Bison.  For Autoconf, however, the
penalty is much higher.

> Should we look for people to make it faster?

For Autoconf, that would benefit to many people, yes.  Gary Vaughan
has already a 2.0 well underway that would allow us to have a faster
engine (by loading .so files), by I guess he doesn't have enough time
to finish it.

>                                               and we didn't think people
>     would be generating parsers with millions of states.
>
> Do people really do that?  I am surprised.  Why?

Because languages grow in size and difficulty.  C++ for instance ;)