Re: Lua 5 Grammar update

[Klaas-Jan Stol <vanderlay@...>]

Mike Pall wrote:

> Hi,
>
> Klaas-Jan Stol wrote:
>  
>
> > > > - Long strings and comments cannot be nested in 5.1.
> > > >        
> > So, just to make sure (before I start implementing the whole thing), you 
> > can't do:
> >
> > [=[I said: [==[Hello World]==] to him]=]
> >    
>
> No, I was imprecise. Sorry. My above sentence should be:
>
>  Long strings and comments --> with the same number of '=' <--
>  cannot be nested in 5.1.
>
> As a corollary, this makes [[xx[[xx]]xx]] a syntax error
> (was legal in 5.0). Different number of '=' nest properly.
>
> $ lua51w6 -e 'print [=[I said: [==[Hello World]==] to him]=]'
> I said: [==[Hello World]==] to him
>
> $ lua51w6 -e 'print [=[I said: [[Hello World]] to him]=]'
> I said: [[Hello World]] to him
>
> $ lua51w6 -e 'print [==[I said: [==[Hello World]==] to him]==]'
> lua51w6: (command line):1: '=' expected near 'him'
>
> $ lua51w6 -e 'print [[I said: [[Hello World]] to him]]'
> lua51w6: (command line):1: nesting of [[...]] is deprecated near '['
>
> Bye,
>     Mike
>
>
>  
good thing I checked ;-)
It makes things a bit more complicated I think. Still doable, but as (^n 
)^n is not a regular language (according to automata ~ and language 
theory) so, the lexer cannot check on number of '(' == number of ')' ), 
this cannot be done by the lexer alone. The parser has to keep track of 
that.

Thanks for your trouble,

klaas-jan