Re: Are Google summer of code 2006 ideas still available?

[Akim Demaille]

Le 1 avr. 07 à 06:46, Joel E. Denny a écrit :

> On Fri, 30 Mar 2007, Akim Demaille wrote:
>
> > - first, design a true AST for Bison
> >   something to represent the grammar we read.  We have more or less
> >   something like this in Bison, but much work is done on it, it's not
> >   "faithful" to the entry, it's already heavily modified.
> >
> >   Once this AST done, then be ready to process it for real, applying
> >   all the transformations we want (elimination of useless things,
> >   elimination of symbolic names, elimination of mid-rule actions,  
> > fuse
> >   the %unions, run semantic checks etc.).
>
> I've often wished that Bison's syntactic and semantic analysis  
> phases were
> more fully separated.  However, this sounds like a major rewrite of  
> vital
> Bison internals.  If someone tackles this over the summer, I hope  
> we can
> find a way to maintain a stable version of Bison in parallel.

IMO there is actually more value to get from this rewrite than
from %import itself: the latter is very reachable from the former.
And a clean AST will considerably ease many other improvements.
Not to mention that some of the bugs we hit would never have
existed in the first place.

> > I wish Bison was in C++...  Joel, WDYT?  This kind of changes would
> > really benefit from moving to some simple, standard, portable, C++.
> > Yeah, I know Paul, there's no such thing as portability, just  
> > sweat :)
>
> With a strong emphasis on *simple* C++, I agree.  I don't want to  
> scare
> away developers by employing hardcore generic programming, multiple
> inheritance, etc.  I imagine a "C++ Don'ts" section evolving in  
> HACKING.

I wholeheartedly agree.  Moreover, I guess harder constructs are
less portable anyway.  What I mean when I say C++ for Bison is
basically classes (with private parts), iostreams, and structures such
as lists and vectors.

> I'm not strong with portability issues, so I'll rely on others to  
> figure
> that part out.

If Paul is on our side and the project is accepted, let ask
rms again.