编号正则表达式捕获的最大数量是多少？

Question

我正在维护一些通过串行无线电读取值的代码,并将它们解压缩到Perl数据结构中:

# Don't yell at me, I didn't write this
if ($command_string =~
    /^.(.)(.).(..)(.)(..)(.)(....)(....)(....)(....)
        (..)(..)(.)(.)(.)(.)(..)(..)(..)(..)(..)(..)(.)(.).......
            (.)........(.)(.).*/sx) {

    $config->{sequence}      = hex(unpack('H2', $1));
    $config->{radio_id}      = hex(unpack('H2', $2));
    ...
    $config->{radio_type}    = hex(unpack('H2', $26));
    $config->{radio_channel} = hex(unpack('H2', $27));
}

这个笨重的捕获正则表达式让我想知道:Perl中编号捕获变量的上限是什么？它会一路走$MAXINT吗？

Answer 1

这个脚本起码至少$N=5000000.之后,它耗尽了内存.

$N = $ARGV[0] || 5000;
$q = '(.)' x $N;
$regex = qr/$q/;
("x" x $N) =~ $regex;
print eval "\$$N";