LPeg: inserting previous captures by substitution

[Александр Машин <alex.mashin@...>]

Dear All,

I wrote a simple LPeg grammar in re.lua syntax that matches a signless 
integer with digits grouped by spaces (there are several ways to do it 
in different cultures):

int <- digits spaces int / digits
digits <- [0-9]+
spaces <- %s+

It works, matching figures like "6 000 000".

I can also remove the spaces with substitution capture:

int <- {~ digits spaces -> '' int / digits ~}
digits <- [0-9]+
spaces <- %s+

It will match "6 000 000" and return "6000000".

But what if I want to return "6000000|6 000 000"? Can I memorise the 
original capture, before removing the spaces and insert it by 
substitution after processed string? I mean, can I do it with pure re 
syntax, without function captures?

Thanks in advance,

Alexander Mashin