dmd support for IDEs and the D tool chain

[Nick Sabalausky]

"Justin Johansson" <no at spam.com> wrote in message 
news:hbamfa$v3b$1 at digitalmars.com...
> Nick Sabalausky Wrote:
>
>> "Ellery Newcomer" <ellery-newcomer at utulsa.edu> wrote in message
>> news:hbak0n$q5b$1 at digitalmars.com...
>> > Nick Sabalausky wrote:
>> >> "Denis Koroskin" <2korden at gmail.com> wrote in message
>> >> news:op.u1v7jdgco7cclz at korden-pc...
>> >>> Yes, it's a DMD port. Unfortunately, there is no other mature D
>> >>> front-end
>> >>> at present. Other folks are working on D compilers (dil, dang, ...) 
>> >>> but
>> >>> the progress is very slow.
>> >>
>> >> FWIW, I've been meaning to try to write a D grammar for GOLD when I 
>> >> get a
>> >> chance (the Haxe grammar I wrote only took a few days). If that pans 
>> >> out
>> >> (depends just how simple and unambiguous the grammar is), then that 
>> >> could
>> >> be
>> >> used with Goldie as a starting point (ie, lex/parse would be taken 
>> >> care
>> >> of.
>> >> Semantic analysis, optimization and back-end would need to be added 
>> >> in).
>> >>
>> >
>> > All but the hard parts :)
>>
>> Yea, like I said, "FWIW" ;)
>>
>> >
>> > I could count the number of places that are ambiguous syntactically or
>> > semantically on one hand, and maybe the number of places that require
>> > arbitrary lookahead also. Do LALR parsers care about arbitrary
>> > lookahead? LL(k) parsers do.
>>
>> Beats me, I'm not nearly as up on parsing theory as I'd like to be. Could
>> you give me a simple example?
>
> There are a zillion tutorials relating to parsing on the web.
>
> Try googling:
>
> parsing theory tutorial
>
> 2nd hit: An introduction to parsing
>

That mentioned, in the section about LL(k), "If both A<B and A<B> are legal 
expressions, where B can be of arbitrary length, then no finite amount of 
look-ahead will allow this to be parsed."

I did a quick test in gold (LALR), and this handles the above just fine:

------------------------------
"Name"    = 'Test'
"Author"  = 'Test'
"Version" = 'Test'
"About"   = 'Test'

"Start Symbol" = <Type1Or2>

<Type1Or2> ::= <Type1> | <Type2>
<Type1> ::= 'A' '<' <Bs>
<Type2> ::= 'A' '<' <Bs> '>'
<Bs> ::= 'B' | <Bs> 'B'

------------------------------

However, that one example alone doesn't necessarily prove that it's always 
doable.