Body::replacePlaceholders

protected function replacePlaceholders(array $params = [])
{
	if(isset($params['content']) && is_string($params['content']))
	{
		$content = $params['content'];
	}
	else
	{
		$content = $this->content;
	}
	if(isset($params['callback']) && is_callable($params['callback']))
	{
		$callback = $params['callback'];
	}
	else
	{
		/** @see Body::getReplaceValue() */
		$callback = [$this, 'getReplaceValue'];
	}
	return preg_replace_callback(
		static::$valuesPattern,
		function(array $matches) use ($callback, $params)
		{
			return call_user_func_array($callback, [$matches, $params]);
		},
		$content
	);
}