Re: Slow Regex - How to Optimize

[dave_the_m]

You code causes the regex to be recompiled each time round the inner loop. A slight rearrangement should improve things:

foreach my $sub ( keys %SUBS ) {
    my $re = qr/[^a-zA-Z]$sub[^a-zA-Z]*\(/;
    foreach my $line ( @sub_code ) {
        if ( $line =~ $re ) { push( @subs, $key ) }
    }
}

Dave.

[ikegami]

That's not true. m/.../ only recompiles if the contents of any interpolated variable has changed. Demo:

use re 'debug';

foreach (qw( abc abc def )) {
   print("==============================\n");
   print("$_\n");
   print("\n");
   /$_/;
}

Update: Oops, I didn't notice you reversed the loops in addition to moving the regexp.

[Anonymous Monk]

great post.. thanks a lot :) it really solved an issue here. reduced the runtime of a usecase from 30 minutes to ~10 seconds. hats off! :)