WC_Shipping::calculate_shipping_for_package PHP Method

    public function calculate_shipping_for_package($package = array(), $package_key = 0)
    {
        if (!$this->enabled || empty($package) || !$this->is_package_shippable($package)) {
            return false;
        }
        // Check if we need to recalculate shipping for this package
        $package_to_hash = $package;
        // Remove data objects so hashes are consistent
        foreach ($package_to_hash['contents'] as $item_id => $item) {
            unset($package_to_hash['contents'][$item_id]['data']);
        }
        $package_hash = 'wc_ship_' . md5(json_encode($package_to_hash) . WC_Cache_Helper::get_transient_version('shipping'));
        $session_key = 'shipping_for_package_' . $package_key;
        $stored_rates = WC()->session->get($session_key);
        if (!is_array($stored_rates) || $package_hash !== $stored_rates['package_hash'] || 'yes' === get_option('woocommerce_shipping_debug_mode', 'no')) {
            // Calculate shipping method rates
            $package['rates'] = array();
            foreach ($this->load_shipping_methods($package) as $shipping_method) {
                // Shipping instances need an ID
                if (!$shipping_method->supports('shipping-zones') || $shipping_method->get_instance_id()) {
                    $package['rates'] = $package['rates'] + $shipping_method->get_rates_for_package($package);
                    // + instead of array_merge maintains numeric keys
                }
            }
            // Filter the calculated rates
            $package['rates'] = apply_filters('woocommerce_package_rates', $package['rates'], $package);
            // Store in session to avoid recalculation
            WC()->session->set($session_key, array('package_hash' => $package_hash, 'rates' => $package['rates']));
        } else {
            $package['rates'] = $stored_rates['rates'];
        }
        return $package;
    }