Re: Parsing of blocks (e.g. foo { bar })

From: Brian Harnish (bharnish_at_technologist.com)
Date: 10/30/03 

Date: Thu, 30 Oct 2003 15:16:30 GMT

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On Thu, 30 Oct 2003 12:36:39 +0000, Tor Houghton wrote:

> Hi,
>
> I'm wondering if there is a more elegant way of parsing "blocks" of data.
[snip]
> Before I go "all out" and complete this section of the code using the
> above technique, I was wondering if there was other (better) ways of doing
> this (for one, I'm not sure how to catch out any errors in the file, for
> instance:
>
> some.host.here {
> another.host {
> /usr
> /opt
> }
> /etc
> /var/mail
> }
>
> .. here the current code fails miserably. Mind you, I'm probably the only
> one going to use this, so that may not be such a big deal :-> )

You didn't really say how you wanted to handle this condition. Is it a
valid condition, or can your program just abort?

If you need to handle that condition, then instead of using the scalar
".."'s flag, use a nesting counter:
my $nest = 0;
while(<CONF>) {
  $nest++ if (/(\S+)\s*\{/);
  $nest-- if (/\}/);
  if($nest == 1) { # Or, $nest >= 1
    # Handle conditions.
  }
}

Actually, thinking about it, aborting would use very similar logic.

 - Brian
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