Simple password construct validator for PHP

phpvalpasswd.php

<?php
/*
 * Simple password construct validator for PHP
 * Joaquim Homrighausen <joho@webbplatsen.se>
 * May 30, 2019
 * TEAMYUJO
 *
 * Do whatever you want with this snippet :)
 *
 * This may not necessarily agree with the section
 * "Strength of Memorized Secrets" in the document
 * from NIST:
 *
 * NIST Special Publication 800-63B
 * Digital Identity Guidelines
 * Authentication and Lifecycle Management
 * https://pages.nist.gov/800-63-3/sp800-63b.html
 */

function password_check_construct ($pstr, $min_length = 8)
{
    //Setup pattern and stuff minimum requested length into it
    if ($min_length < 4) {
        //We need at least four characters to satisfy our regexp
        $min_length = 4;
    }
    $match_rules = '/^(?=.{'.(int)$min_length.',})(?=.*[a-z])(?=.*[0-9])(?=.*[A-Z])(?=.*[[:punct:]]).*$/';

    //Require at least one a-z, one A-z, one 0-9, and one punctuation/special character
    if (preg_match ($match_rules, $pstr) === 1) {
        return (true);
    }
    return (false);
}

?>