PHP: Text Spinner Class - Nested spinning supported.

spintax.php

<?php
/**
 * Spintax - A helper class to process Spintax strings.
 * @name Spintax
 * @author Jason Davis - https://www.codedevelopr.com/
 * Tutorial: https://www.codedevelopr.com/articles/php-spintax-class/
 * Modified by Mark Larsen:
 * Added ability so that a fixed output can be returned.
 * Modified by David Strencsev:
 * Refactor and regular expression lazy optimization.
 */
class SpintaxSpinner
{
    protected $seed;

    public function __construct($seed = null)
    {
        if (null !== $seed) {
            $this->seed = crc32($seed);
        }
    }

    public function execute($spinTemplate)
    {
        return preg_replace_callback(
            '/\{(((?>[^\{\}]+)|(?R))*?)\}/x',
            array($this, 'replace'),
            $spinTemplate
        );
    }

    private function replace($text)
    {
        $text  = $this->execute($text[1]);
        $parts = explode('|', $text);
        if ($this->seed) {
            // We want the same version returned each time
            mt_srand($this->seed);
        }

        return $parts[mt_rand(0, count($parts) - 1)];
    }
}

/* EXAMPLE USAGE */
$spintax = new SpintaxSpinner();
$string = '{Hello|Howdy|Hola} to you, {Mr.|Mrs.|Ms.} {Smith|Williams|Davis}!';
echo $spintax->execute($string), PHP_EOL;

/* NESTED SPINNING EXAMPLE */
echo $spintax->execute('{Hello|Howdy|Hola} to you, {Mr.|Mrs.|Ms.} {{Jason|Malina|Sara}|Williams|Davis}'), PHP_EOL;

/* PREDICTABLE EXAMPLE */
$spintax = new SpintaxSpinner('someId');
echo $spintax->execute('{Hello|Howdy|Hola} to you, {Mr.|Mrs.|Ms.} {{Jason|Malina|Sara}|Williams|Davis}'), PHP_EOL;
echo $spintax->execute('{Hello|Howdy|Hola} to you, {Mr.|Mrs.|Ms.} {{Jason|Malina|Sara}|Williams|Davis}'), PHP_EOL;