Re: Any LPEG tutorial for laymen ?

[David Crayford <dcrayford@...>]

Right, I'm learning here but now I want to grok another pattern.

  Local Socket:   2001:db8:4545:2:0:9ff:ac11:4519..750

I want discard the label and extract the ipaddr and port. In REXX I 
would code

p = "Local Socket:   2001:db8:4545:2:0:9ff:ac11:4519..750"
parse var p . ":" ipaddr ".." port
say ipaddr port

where the . discards anything up to the pattern template.

When I master Lua I will write a library to simulate the REXX parse 
instruction. Steve Donovan has a great library that I will use as 
inspiration to do that.

I've fallen in love with Lua but IMHO REXX is much simpler for scraping 
report output.


On 25/09/2013 1:06 PM, Philipp Janda wrote:
> Hi!
>
> Am 25.09.2013 06:50 schröbte David Crayford:
> > Thanks. This is how dumbstruck I am WRT pattern matching. I want to
> > parse the following piece of netstat output
> >
> > SKRBKDC  00000099 UDP
> >    Local Socket:   172.17.69.30..464
> >    Foreign Socket: *..*
> >
> > The top line is the user, connection id and state. All I want to do is
> > capture three whitespace seperated words.
> >
> > In REXX I would do this:
> >
> > parse var line userid connid state
> >
> > What is the most succinct way of doing something similar in Lua?
>
> print( line:match( "(%w+)%s+(%w+)%s+(%w+)" ) )
>
> %w matches a single "word"-character (letters, numbers, and _).
> %w+ means: at least one of those, and as much as possible.
> (%w+) means: capture the match (copy the matching substring to the 
> return values of `line:match` (if the whole match succeeds)).
> %s matches a single whitespace character (not just space, but tab, and 
> newline, etc. as well).
> %s+ means: match at least one whitespace, but as much as possible at 
> that position.
>
> Philipp