egex_iterator</span></code></a> or <a class="link" href="regex_token_iterator.html" title="regex_token_iterator"><code class="computeroutput"><span class="identifier">regex_token_iterator</span></code></a>) in order for
        this member function to be defined and return useful information.
      </p>
<p>
        <span class="bold"><strong>Rationale</strong></span>: Enabling this feature has several
        consequences:
      </p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: