Re: Parse::RecDescent grammar that winds its way all the way back to start

Okay, I think that I have come up with a workable solution. (Given that the only parser-tool that I have to work with, in this case, is this one ...)

Well, the first thing that I did, as you can see, is to shrink the size of the grammar-example in the original post to “just an example.” (Sorry about that.)

Then, I came up with a production like this:

  job_list : job_statement job_list
             | #NOTHING
[download]

The rule does recurse. When the “nothing” case is encountered (which simply means that “whatever we are looking at now, whatever it is, is not a job_statement”) the result of the production is a string consisting of the name of the nonterminal (“job_list”). The action code (not shown) ignores that.

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Re^2: Parse::RecDescent grammar that winds its way all the way back to start by ikegami (Patriarch) on Sep 23, 2010 at 23:02 UTC
Well, the first thing that I did, as you can see, is to shrink the size of the grammar-example in the original post to “just an example.” You still not clear what you want out of it. If you simply don't want it to fail, use a production that always matches instead of using `<error>`. Then, I came up with a production like this: `job_list : job_statement job_list \| #NOTHING` [download] will match the same as `job_list : job_statement(s?)` [download]	[reply] [d/l] [select]

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Re^2: Parse::RecDescent grammar that winds its way all the way back to start
by ikegami (Patriarch) on Sep 23, 2010 at 23:02 UTC

Well, the first thing that I did, as you can see, is to shrink the size of the grammar-example in the original post to “just an example.”

You still not clear what you want out of it.

If you simply don't want it to fail, use a production that always matches instead of using <error>.

Then, I came up with a production like this:

job_list : job_statement job_list
         | #NOTHING
[download]

will match the same as

job_list : job_statement(s?)
[download]

[reply]
[d/l]
[select]