lpeg.Cp(patt)

[Eduardo Ochs <eduardoochs@...>]

Hello list,

I am trying to reimplement in LPeg a recursive-descent parser that I

wrote by hand, and - for some reasons that I'll explain in a next

message if it turns out that my doubts are not too dumb - I had to use

lpeg.Cmt(f) in several of my sub-patterns, and I realized that my work

would be much easier if lpeg.Cp accepted a pattern as an argument,

i.e., if instead of

  lpeg.C(patt)  the match for patt plus all captures made by patt

  lpeg.Cp()     the current position (matches the empty string)

we had:

  lpeg.C(patt)  the match for patt plus all captures made by patt

  lpeg.Cp(patt) if patt is nil, then the current position;

                if patt is a pattern, then the position after

                matching patt (if the match succeeds), plus all

                captures made by patt

Anyone knows a way to simulate the behavior I'm suggesting for lpeg.Cp

when its `patt' is not nil?

  Cheers and thanks in advance,

    Eduardo Ochs

    eduardoochs@gmail.com

    http://angg.twu.net/

P.S.: I _think_ I know two ways for doing that: one is a very, very,

_very_ ugly hack using the fact that `patt / f' is supposed to

evaluates f as late as possible (modulo optimizations), and the other

way involves running table.pack on the captures of patt*lpeg.Cp(),

then returning the last value in that table plus the unpacking of the

rest... But there must be better ways! =|