Re: Lpeg Cg question

[Pierre-Yves Gérardy <pygy79@...>]

On Tue, May 13, 2014 at 10:16 PM, Andrew Starks <andrew.starks@trms.com> wrote:

> ...because the manual[1] says:
>
>      An anonymous group serves to join values from several captures
> into a single capture.
>
>
>
> What am I missing?

It concerns LPeg's own representation of captures. Groups are
flattened when returned.

For example, in a folding capture, groups are treated as a single
capture, and the callbacks receives all sub-captures as arguments.

There are also some inconsistencies in how other captures handle groups:

    (Cg(C(1) * C(1)) * Cg(C(1) * C(1)) / 2):match"abcd"    --> b
    (Cg(C(1) * C(1)) * Cg(C(1) * C(1)) / "%2"):match"abcd" --> c

`/2` takes the second production of the capture stream, whereas
`/"%2"` takes the value of the second group, truncated to one value.

—Pierre-Yves