in reply to Re: Better way than tail-recursion in Parse::RecDescent?
in thread Better way than tail-recursion in Parse::RecDescent?

I haven’t spent enough time looking at <leftop> although I am given to understand that the (s /;/) syntax is supposed to be equivalent...

One issue that, as I now recall, was one reason for my latching-on to tail recursion ... was error messages.   If there was an error somewhere some statement, deep down in the file, the only error-message that actually popped-out was from the <error> production of the outermost rule.   I freely admit that I think I have built stuff that “works, sort of ...”   Well, actually it works very well, in terms of the results that it now allows us to obtain.   But I know that it was not built properly and I would like to fix it now rather than later.   Yes, I am running this thing on a machine that’s big enough to run 20 or more SAS® jobs at once.   But, because the results are already well on their way to being “mission critical” for this workgroup, I know that insufficiency in these parsers will definitely come back to bite me soon.

Can anyone point me to some really good, in depth material on substantial applications/case-studies of Parse::RecDescent?   I need to sip from a firehose on how to really use this thing right.   I need to read war-stories in detail.

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Re^3: Better way than tail-recursion in Parse::RecDescent?
by ikegami (Patriarch) on Oct 30, 2010 at 19:03 UTC

    I presume you have 

    {
   use strict;
   use warnings;
}

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    inside your grammar. Add 

    no warnings 'recursion';

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    to that block.

    You are precompiling, right? You can see the generated parser by looking at that .pm file.

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Re^3: Better way than tail-recursion in Parse::RecDescent?
by markhh (Novice) on Dec 02, 2010 at 23:36 UTC
    How about something like: 
    {
my @stmterrs;
}
DDL_stmtlist: DDL_statement(s? /;/) {
    if (@stmterrs) {
      push(@{$thisparser->{errors}}, @stmterrs);
      undef;
    } else { 1; } }

DDL_statement: whatever
   |  {
       push(@stmterrs, ["something fishy", $thisline]);
      } <resync: /[^;]*/s >

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    DDL_statement will now "succeed" until the end of the input. But you get to keep every error you encounter along the way.
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