CYK parser: how does lark work with CYK?

[Oleksii-Hovderchak]

Has anybody tested the CYK parser?

Afaik, the grammar should be in a CNF, like this:

S -> AB | BC
A -> BA | a
B -> CC | b
C -> AB | a

So that the string 'baaba' should be now parsed well, but I have errors right now.

Tried to find some examples on the github or some tests in your code or at least a grammar example and I failed.

Could anyone help with that? Maybe I'm missing smth, thank is advance!

[MegaIng]

Well, you probably don't want to use cyk in lark. It is more there for backwards compatibility.

But anyway, how are you calling Lark? what errors do you get? You at least need to change the syntax to the lark syntax.

[MegaIng]

But as to why not cyk:

• cyk is the least supported parser option in Lark
• cyk is the slowest option
• cyk will be removed in 1.0 (unless you have good arguments as to why not)

[Oleksii-Hovderchak]

oh thanks a lot! But why the collision started? CYK does not support like 'terminal reference'?

[Oleksii-Hovderchak]

omg I guess I got it, CYK uses the standard lexer, right? So here is where earley also wins

[MegaIng]

Yes.

[Oleksii-Hovderchak]

Great, thanks for your help!
Good luck!