为什么我的 Perl 正则表达式会导致无限循环？

Question

我有一些代码可以抓取一些文本的“中间”； 具体来说，在foo $someword 和下一个foo $someword 之间。

但是，发生的情况是它卡在第一个“中间”处，并且不知何故内部字符串位置没有增加。

输入数据是一个带有换行符的文本文件：它们无关紧要，但使打印更容易。

my $component = qr'foo (\w+?)\s*?{';

while($text =~ /$component/sg)
{
    push @baz, $1; #grab the $someword
}

my $list = join( "|", @baz);
my $re = qr/$list/; #create a list of $somewords

#Try to grab everything between the foo $somewords; 
# or if there's no $foo someword, grab what's left.

while($text=~/($re)(.+?)foo ($re|\z|\Z)/ms)   
#if I take out s, it doesn't repeat, but nothing gets grabbed.
{
#   print pos($text), "\n";   #this is undef...that's a clue I'm certain.
    print $1, ":", $2; #prints the someword and what was grabbed.
    print "\n", '-' x 20, "\n";
}

Answer 1

更新：另一个更新来处理您要提取的文本中出现的'foo'：

use strict;
use warnings;

use File::Slurp;

my $text = read_file \*DATA;

my $marker = 'foo';
my $marker_re = qr/$marker\s+\w+\s*?{/;

while ( $text =~ /$marker_re(.+?)($marker_re|\Z)/gs ) {
    print "---\n$1\n";
    pos $text -= length $2;
}

__DATA__
foo one {
one1
one2
one3

foo two
{ two1 two2
two3 two4 }

that was the second one

foo three { 3
foo 3 foo 3
foo 3
foo foo

foo four{}

输出：

--- 一个1 一个2 一个3 --- 二1 二2 二3 二4 } 那是第二个 --- 3 富 3 富 3 富 3 富富 --- }