Re: PowerLoom's BNF usage

Hans Chalupsky <[email protected]> Fri, 4 Jul 2008 09:00:48 -0700
Newsgroups gmane.comp.ai.powerloom
Message-ID <[email protected]>
Rich,

the PowerLoom grammar was developed by a motivated visitor to our
group, but we never scrutinized it much nor used it for anything, so
it probably is incomplete, inconsistent and not quite up-to-date.
Given that more people are getting serious about using it, we should
fix that, firm it up and bring it in-line with the upcoming
Common-Logic standard.  That would also address the character set
questions you voiced previously.

With respect to the questions below, the only thing incorrect was your
interpretation of braces, which we use as a grouping construct.  Since
they also mean something in Texinfo and require proper quoting, it
looks like some of them didn't survive into the formatted version of
the manual, we need to fix that.

Hans

>>>>> Rich Morin <[email protected]> writes:

> I've been digging into Chapter 11 of the manual, in order to
> write a second-level parser (ie, recognize logsent, etc.).

> The BNF isn't exactly standard (or even correct in some places),
> so I have been getting confused about some rather basic things.
> Can someone confirm or deny (and then clarify) these statements?

> asterisk "*"

>   An asterisk means "zero or more of this item".

> braces "{...}"

>   Braces mean "zero or more of these items".

> brackets "[...]"

>   Brackets mean "zero or one of these items".

> parentheses "(...)"

>   Parentheses stand for themselves,
>   rather than acting as grouping operators.

> plus sign "+"

>   A plus sign means "one or more of this item".

> -r
> -- 
> http://www.cfcl.com/rdm            Rich Morin
> http://www.cfcl.com/rdm/resume     [email protected]
> http://www.cfcl.com/rdm/weblog     +1 650-873-7841

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