/**
* Constructs an instance of this class.
*
* @param Unit $parent
* @param string $symbol
* @param string $quantity
*/
public function __construct(Unit $parent, $symbol, $quantity)
{
if (!$parent->isStandardUnit()) {
throw new \InvalidArgumentException(sprintf('Parent unit "%s" is not a standard unit.', $parent->getSymbol()));
}
parent::__construct($quantity);
$this->parent = $parent;
$this->symbol = $symbol;
}
/**
* Constructs an instance of this class.
*
* @param CompoundElement[]|Unit $elements
* @param string $quantity
* @param string $symbol
*/
public function __construct($elements, $quantity = '', $symbol = '')
{
parent::__construct($quantity);
$this->symbol = $symbol;
if ($elements instanceof self) {
$this->elements = $elements->elements;
} elseif (is_array($elements)) {
$this->elements = $elements;
} else {
throw new \InvalidArgumentException(sprintf('Expected a ProductUnit or an array of CompoundElement but got "%s"', get_class($elements)));
}
}
