sub CheckOptimizer
{
    my $text  = shift; # The first argument is the text to check.
    my $start = undef; # We'll note here where the regex is first applied.

    my $match = $text =~ m{
      (?{ $start = $-[0] if not defined $start}) # Save the first starting position
      \d # This is the regex being tested
    }x;

    if (not defined $start) {
        print "The whole match was optimized away.\n";
        if ($match) {
            # This can't possibly happen!
            print "Whoa, but it matched! How can this happen!?\n";
        }
    } elsif ($start == 0) {
        print "The match start was not optimized.\n";
    } else {
        print "The optimizer started the match at character $start.\n"
    }
}




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Copyright 1997-2024 Jeffrey Friedl