019">here</a>.</li>
</ul>
</div>
<div id="issues" class="section level2">
<h2 class="hasAnchor">
<a href="#issues" class="anchor"></a>Issues</h2>
<p>Initially, the PCRE (perl set) version of regexpr repeatedly scanned the entire input string to ensure it is valid UTF-8, which accounts for the time being proportional to the square of the number of pattern matches in the input strings, resulting in quadratic complexity. (same was observed in the PCRE version of <code><a href="https://rdrr.io/r/base/strsplit.h