Let's stop parser Hell

[Tobias Pankrath]

On Sunday, 8 July 2012 at 09:14:32 UTC, Dmitry Olshansky wrote:
> On 08-Jul-12 13:05, Tobias Pankrath wrote:
>>>> Yup, LL(*) is my favorite so far.
>>>
>>> That's Terence Parr's discovery, right? I've always liked 
>>> ANTLR, so if
>>> PEGs turn out to have issues LL(*) sounds like a promising 
>>> alternative.
>>
>> We should also consider using GLR if LL(*) doesn't work.
>
> GLR ... are you serious? It still does parsing in n^3 if I'm 
> not mistaken.

Since GLR can parse any CFG the upper bound is in O(n^3), but the 
actual performance seems to depend on the grammar.

 From Elkhound [1]
> It should be competitive with Bison for LALR (fragements of) 
> grammars, and degrade gracefully from there. On the scale of 
> grammar nondeterminism, from none
> (LALR) to some to lots, "some" is the niche Elkhound is going 
> after.
> These goals are driven by Elkhound's primary application, the 
> Elsa C++ Parser. In essence, Elkhound came about because I 
> wanted to apply automatic parsing technology to parsing C++, 
> but found exiting systems inadequate.

So it seems to me that it is not worse than PEG if you have a 
grammar with
reasonable many ambiguities.

Performance is one thing, but you should be able to express your 
language in the underlying formalism without too many hurdles.