Text::isOnlyEmoji

static function isOnlyEmoji($text)
{
	$total = 0;
	$count = 0;

	$pattern = '%(?:
			xF0[x90-xBF][x80-xBF]{2} # planes 1-3
			| [xF1-xF3][x80-xBF]{3} # planes 4-15
			| xF4[x80-x8F][x80-xBF]{2} # plane 16
		)%xs';
	$text = preg_replace_callback($pattern, function () {return "";}, $text, 4-$total, $count);
	$total += $count;

	if ($total > 3)
	{
		return false;
	}

	if ($total <= 0)
	{
		return false;
	}

	$text = trim($text);

	return !$text;
}