[C2hs] Re: [Gtk2hs-devel] A new lexer/parser for c2hs

[Manuel M T Chakravarty]

Duncan Coutts:
> On Wed, 2005-06-08 at 21:12 +1000, Manuel M T Chakravarty wrote:
> > Duncan Coutts:
> > > On Wed, 2005-06-01 at 22:16 +1000, Manuel M T Chakravarty wrote:
> > > > Sounds good to me.
> > > 
> > > You can review the cleaned up versions of the lexer and parser here:
> > > http://cvs.sourceforge.net/viewcvs.py/gtk2hs/gtk2hs/tools/c2hs/c/CLexer2.x?only_with_tag=branch-0-9-8&view=markup
> > > http://cvs.sourceforge.net/viewcvs.py/gtk2hs/gtk2hs/tools/c2hs/c/CParser2.y?only_with_tag=branch-0-9-8&view=markup
> > 
> > Looks great!  Just two minor points:
> > 
> > * In CLexer2.idkwtok, why didn't you use string literals (but explicit 
> >   lists of characters instead)?
> 
> Because GHC translates the former into a sequence of string comparisons,
> but the latter using its effecient pattern matching algorithm. So the
> former is a linear search, the latter is more like a trie. It makes a
> significant difference to the speed of the lexer. We could of course use
> an explicit trie data structure if we had one to hand.

Ah!  Bad GHC...

> > * I also prefer lines with max. 80 characters (I usually work on my 
> >   laptop and its screen is not that big).
> 
> Ok, I'll see if I can reformat it before submitting it.

Thanks!

> > So, if you would prepare a patch against the mainline c2hs in the darcs
> > repo, I'd be more than happy to replace the existing lexer and parser
> > with your new version.
> 
> Great! I fear I may have to leave the required build system changes to
> you. We're using a different build system.

No problem.  I am grateful for the effort you made to implement this in
the first place.

Manuel