Beefy Boxes and Bandwidth Generously Provided by pair Networks
Think about Loose Coupling
 
PerlMonks  

Re: (jeffa) 3Re: More Variable length regex issues

by dextius (Monk)
on Jun 09, 2003 at 03:47 UTC ( #264225=note: print w/replies, xml ) Need Help??


in reply to (jeffa) 3Re: More Variable length regex issues
in thread More Variable length regex issues

Sheesh, -1 reputation abounds on this one..

Ok, I'm parsing USMTF, it has repeatable fields all through it. I can use split, but I have non-repeatable fields that require more delicate processing..

Doing a split will ignore much of the value of parsing using a regex. The problem is, the target text I am matching against is not fixed length, not even fixed patterns. The last few elements can be repeated infinitely.. I guess I'll go back to mastering regular expressions v2 and see if I missed something..

Thank you for your time..

ps. I am forced to using Cold Fusion MX, which is powered by Jrun, which uses the oro module. I prefer Perl to solving problems, but I have to take care of this first..

  • Comment on Re: (jeffa) 3Re: More Variable length regex issues

Replies are listed 'Best First'.
(jeffa) 5Re: More Variable length regex issues
by jeffa (Bishop) on Jun 09, 2003 at 04:36 UTC
    You keep on using that word 'split' ... i do not think you know what it means. ;) Consider the following:
    my $str = 'foo,bar,moo,cow'; my @value = $str =~ m/(\w+)\,?/g; print "@value\n"; @value = split(',',$str); print "@value\n"
    They both achieve the same results, and guess which one is easier to understand?

    You say have non-repeatable fields, how does using a regex make this easier than split? What do you think split uses to split? A regex! Besides, oro has a family of split functions. You could always do a series of splits if multiple delimiters are used:

    my $str = 'a,b,c:d,e,f:g,h,i'; my @part = split(':',$str); foreach my $part (@part) { my @subpart = split(',',$part); print "@subpart\n"; }
    The split functions found in the org.apache.oro package can do this, you just have to jump through more hoops. ;) Not that it matters, but one of my beefs about Java is not being able to process lists easily like you can in Perl:
    print $_,$/ for map split(',',$_), split(':', $str);
    Best of luck.

    jeffa

    L-LL-L--L-LL-L--L-LL-L--
    -R--R-RR-R--R-RR-R--R-RR
    B--B--B--B--B--B--B--B--
    H---H---H---H---H---H---
    (the triplet paradiddle with high-hat)
    
      I am not clearly explaining this issue.. Your examples are not exactly detailing my criteria because I am not fully explaining my problem, I apologize.

      I have a string of characters that use the same delimiter. Some of the fields are mandatory, some are optional, and some may be repeated infinitely. I want to extract those values AND validate the fields all at once within a single regular expression. I want these values to be available to me afterward. A simple example..

      use Data::Dumper; my $foo = "one,123,a s d f,a,b,c,d,e,f,g,h"; my @bar = $foo =~ /^([a-z]{3}),([0-9]{3}),([a-z\s]{1,7}),(?:([a-z]),|( +[a-z]$)){1,}/; print Dumper(\@bar);

      Consider everything after the 3rd element to repeat, possibly to infinity, but we need to make sure they are single characters, otherwise I want the entire regex to fail immediately.

      Again, thank you for your time, you have spent more than enough time working with me, and I very much so appreciate it..

        Whoa, whoa, whoa there. Why do you have the (arbitrary) requirement that everything has to be done in the regex? IMHO, long regexen are what lead to the stereotype of perl looking like line-noise. I would suggest using split, and then validating the elements that you need to validate in separate statements. If you'd like, you can gather up your validation and pack it in to a subroutine. Just try to think of the poor bastard who has to come behind you and maintain the code.

        Also, minor nit, "infinite" ne "arbitrary". If there were an infinite number of fields, not only would you have run out of disk space by now, but you couldn't do anything with it, since you couldn't hold it in memory. ;) Arbitrary means "as much as you want", whereas infinite means "without end".

        thor

        Do you still think that you have to perform this task with one regular expression? (and a horribly, unreadable, broken one at that.) split is perfectly cabable of stopping after it finds the, say, 3rd element. Then you can do something different with the rest:
        use Data::Dumper; my $foo = 'one,123,a s d f,a,b,c,bad,e,f,g,h'; my @first = split(',',$foo,4); my @rest = split(',',pop @first); print Dumper \@first, \@rest; for (0..$#rest) { die "index $_ is bad: '$rest[$_]'" if length($rest[$_]) != 1; }
        Think in chunks. Don't try to swallow the whole pill at once.

        jeffa

        L-LL-L--L-LL-L--L-LL-L--
        -R--R-RR-R--R-RR-R--R-RR
        B--B--B--B--B--B--B--B--
        H---H---H---H---H---H---
        (the triplet paradiddle with high-hat)
        

Log In?
Username:
Password:

What's my password?
Create A New User
Domain Nodelet?
Node Status?
node history
Node Type: note [id://264225]
help
Chatterbox?
and the web crawler heard nothing...

How do I use this? | Other CB clients
Other Users?
Others meditating upon the Monastery: (3)
As of 2022-05-17 11:53 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?
    Do you prefer to work remotely?



    Results (65 votes). Check out past polls.

    Notices?