Re^2: Matching against list of patterns

[Random_Walk]

Tachyon,
I have a similar problem, over six hundred complex regexen to match against a busy logfile and related messages to issue depending on which regexps were matched. much the same problem as the OP

If I understand the regexp engine caching the compiled version of a regex if it is not going to change then I think this should be a reasonably efficient approach. Am I on the right tracks ? and is the /o unrequired as I have already interpolated the variable when the regex is first called ?

#!/usr/local/bin/perl -w
use strict;

my ($i, $compile_me, @names)=(1, "{my \@matches;", "no match");

while (<DATA>) {
    next if /^\s*$/;
    last if /END CONFIG/;
    chomp;
    my ($name, $reg)=split;
    push @names, $name;
    $compile_me.="push \@matches, $i if /$reg/o;";
    $i++;
}
$compile_me.="\@matches}";

while (<DATA>) {
    chomp;
    print "\nmatches found for $_\n";
    my @matches=eval $compile_me;
    foreach (@matches) {
        print $names[$_] , "\n"
    }
}

__DATA__
Fred_and_Friends  fr.d
Paul_and_co       paul
some_numbers      \d{2}
freud_likes_fred  fr

END CONFIG

freud
fred
NaNa
pauline
12312sdfsdf
2

Update with speed test

I have now run a comparative test over 300^H^H^H, sorry 416 lines of log, with my 672 pattern matches. First using the eval of a string containing all the regexen and returning match index numbers as above. Second is my old naive code holding an array with the regexen and doing a foreach through it against each line. I did not use the /o for the reasons given above it works fine without it

>time ./Monitor.fast
real    0m1.49s
user    0m0.68s
sys     0m0.58s

>time ./Monitor
real    0m19.47s
user    0m14.69s
sys     0m0.50s
>

I think the numbers speak for themselves

Cheers,
R.