title: Meaning of a bit of perl's Regular Expression?
body: <p>I'm translating code from perl and I've come accross the following line </p>
  
  <pre><code>$text =~ s/([?!\.][\ ]*[\'\"\)\]\p{IsPf}]+) +([\'\"\(\[\¿\¡\p{IsPi}]*[\ ]*[\p{IsUpper}])/$1\n$2/g;
  </code></pre>
  
  <p>My question is, what does \p{IsPf} and \p{IsPi} match to? I've tried searching online for it but haven't found anything... </p>