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perlregex-greedyfix-protocol

perl regex too greedy

I went through similar questions asked by other members and applied (or tried to apply) solutions from their inquiry but they did not work on my issue. My pattern match and grouping is too greedy and does not stop at first pipe(|). If I get more specific, I think it can but I'm trying to figure out how I can stop the pattern match at the first instance of the pipe?

Here are couple of lines 

09:30:00.063|IN:|8=FIX.4.2|9=206|35=D|34=5159|49=CLIENT|52=20191024-13:30:00.050|56=SERV|57=DEST|1=05033|11=ABZ5702|15=USD|21=1|38=2000|40=2|44=92.48|47=A|54=5|55=RC|60=20191024-13:30:00.050|111=0|114=N|336=X|5700=AP|9281=SOV|10=202
09:37:21.208|IN:|8=FIX.4.2|9=170|35=D|34=5184|49=CLIENT|52=20191024-13:37:21.206|56=SERV|57=ATXB|1=J5129|11=136404|15=USD|21=1|38=100|40=2|44=1.39|47=A|54=2|55=DIW|59=2|60=20191024-13:30:00.206|10=029

I'm expecting my perl script to return the following output from the above data:

09:30:00.063|13:30:00.050|ABZ5702
09:37:21.208|13:37:21.206|136404

I tried all this and few other veriations but could not get it to produce the above output:

    #$msg =~ s/([^|]*).*|52=([^|]*).*|11=([^|]*).*/$1|$2|$3/;
    $msg =~ s/(.+)\|??.*|52=([^|]*).*|11=([^|]*).*/$1|$2|$3/;
    #$msg =~ s/^([^|]*).??|52=([^|]*).??|11=([^|]*).*/$1|$2|$3/;
    #$msg =~ s/^([^\|??]*).*|52=([^\|??]*).*|11=([^\|??]*).*/$1|$2|$3/;
    #$msg =~ s/(.*\|??).*|52=(.+\|??).*|11=(.+\|??).*/one $1|two $2|three $3/;
    #$msg =~ s/(.*?|).*|52=(.*?|).*|11=(.*|?).*/$1|$2|$3/;
    #$msg =~ /(.*)|??.*|52=(.*)|??.*|11=(.*)|??.*/$1|$2|$3/;
    #$msg =~ s/|.*-[0-3][0-9]:/|/;

print "$msg\n";```

I realize there are other more than one way to skin the cat but there are cases where I need to use the pattern match approach. How can I get it to produce the expected output using the pattern matching where it stops each group at first pipe(|)? Can someone tell me what am I doing wrong?

Solution

  • Try this: s/(.*?)\|.*\|52=([^|]*).*\|11=([^|]*).*/$1 $2 $3/;

    There were a couple of pipe delimiters that needed escaping.

    You need to look at non-greedy matching https://docstore.mik.ua/orelly/perl/cookbook/ch06_16.htm

    The first matching group is (.*?) instead of (.*). The ? means we match as little as possible.

    In general, for parsing FIX in perl, as long as there are no repeating groups, I would recommend splitting on | first and then creating a hash of tag-value pairs.