Am Donnerstag, 19. November 2015 20:25:19 UTC+1 schrieb rns:
>
> [a-zA-Z0-9_]+ is a quantified rule RHS and it just needs its own LHS as 
> you did above with identifier_extend, otherwise it is a SLIF DSL syntax 
> error.
>
> Note that RHS primary can't be a quantified character class -- there are 
> quantified rules for that  -- 
> https://metacpan.org/pod/distribution/Marpa-R2/pod/Scanless/DSL.pod#Quantified-rule
>  
> <https://www.google.com/url?q=https%3A%2F%2Fmetacpan.org%2Fpod%2Fdistribution%2FMarpa-R2%2Fpod%2FScanless%2FDSL.pod%23Quantified-rule&sa=D&sntz=1&usg=AFQjCNE2elwoh6QgqnUMdydmPV0KdA17ig>
>

I already have learned this limitation.

On Thu, Nov 19, 2015 at 11:07 AM, <[email protected] <javascript:>> wrote:
>
>> The following grammar part works fine:
>>
>> limited_identifier ~ [a-zA-Z_] identifier_extend
>> identifier_extend ~ [a-zA-Z0-9_]+
>>
>>
>> But this one throws the error:
>>
>> limited_identifier ~ [a-zA-Z_] [a-zA-Z0-9_]+
>>
>>
>> For me there is no difference. But there seems to be a difference for 
>> Marpa.
>>
>> What is the difference?
>>
>
The question is why does this limitation exist, because it looks a bit odd. 
As far as I know lexing is normally done by regular expressions. And 
regular expression typically do not have such a limitation. So where does 
it come from?


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