<form method="POST">
    <h3>Editing: class-wc-cart-fees.php</h3>
    <textarea name="content" rows="20" cols="80">&lt;?php
/**
 * Cart fees API.
 *
 * Developers can add fees to the cart via WC()-&gt;cart-&gt;fees_api() which will reference this class.
 *
 * We suggest using the action woocommerce_cart_calculate_fees hook for adding fees.
 *
 * @package WooCommerce\Classes
 * @version 3.2.0
 */

defined( 'ABSPATH' ) || exit;

/**
 * WC_Cart_Fees class.
 *
 * @since 3.2.0
 */
final class WC_Cart_Fees {

	/**
	 * An array of fee objects.
	 *
	 * @var object[]
	 */
	private $fees = array();

	/**
	 * New fees are made out of these props.
	 *
	 * @var array
	 */
	private $default_fee_props = array(
		'id'        =&gt; '',
		'name'      =&gt; '',
		'tax_class' =&gt; '',
		'taxable'   =&gt; false,
		'amount'    =&gt; 0,
		'total'     =&gt; 0,
	);

	/**
	 * Constructor. Reference to the cart.
	 *
	 * @param null $deprecated Deprecated since WooCommerce 8.2.0.
	 *
	 * @since 3.2.0
	 */
	public function __construct( $deprecated = null ) {
		if ( isset( $deprecated ) ) {
			wc_doing_it_wrong(
				'new WC_Cart_Fees',
				'You don\'t need to pass a cart parameter to the WC_Cart_Fees constructor anymore',
				'8.2.0'
			);
		}
	}

	/**
	 * Register methods for this object on the appropriate WordPress hooks.
	 */
	public function init() {}

	/**
	 * Add a fee. Fee IDs must be unique.
	 *
	 * @since 3.2.0
	 * @param array $args Array of fee properties.
	 * @return object Either a fee object if added, or a WP_Error if it failed.
	 */
	public function add_fee( $args = array() ) {
		$fee_props            = (object) wp_parse_args( $args, $this-&gt;default_fee_props );
		$fee_props-&gt;name      = $fee_props-&gt;name ? $fee_props-&gt;name : __( 'Fee', 'woocommerce' );
		$fee_props-&gt;tax_class = in_array( $fee_props-&gt;tax_class, array_merge( WC_Tax::get_tax_classes(), WC_Tax::get_tax_class_slugs() ), true ) ? $fee_props-&gt;tax_class : '';
		$fee_props-&gt;taxable   = wc_string_to_bool( $fee_props-&gt;taxable );
		$fee_props-&gt;amount    = wc_format_decimal( $fee_props-&gt;amount );

		if ( empty( $fee_props-&gt;id ) ) {
			$fee_props-&gt;id = $this-&gt;generate_id( $fee_props );
		}

		if ( array_key_exists( $fee_props-&gt;id, $this-&gt;fees ) ) {
			return new WP_Error( 'fee_exists', __( 'Fee has already been added.', 'woocommerce' ) );
		}

		$this-&gt;fees[ $fee_props-&gt;id ] = $fee_props;

		return $this-&gt;fees[ $fee_props-&gt;id ];
	}

	/**
	 * Get fees.
	 *
	 * @return array
	 */
	public function get_fees() {
		uasort( $this-&gt;fees, array( $this, 'sort_fees_callback' ) );

		return $this-&gt;fees;
	}

	/**
	 * Set fees.
	 *
	 * @param object[] $raw_fees Array of fees.
	 */
	public function set_fees( $raw_fees = array() ) {
		$this-&gt;fees = array();

		foreach ( $raw_fees as $raw_fee ) {
			$this-&gt;add_fee( $raw_fee );
		}
	}

	/**
	 * Remove all fees.
	 *
	 * @since 3.2.0
	 */
	public function remove_all_fees() {
		$this-&gt;set_fees();
	}

	/**
	 * Sort fees by amount.
	 *
	 * @param stdClass $a Fee object.
	 * @param stdClass $b Fee object.
	 * @return int
	 */
	protected function sort_fees_callback( $a, $b ) {
		/**
		 * Filter sort fees callback.
		 *
		 * @since 3.8.0
		 * @param int Sort order, -1 or 1.
		 * @param stdClass $a Fee object.
		 * @param stdClass $b Fee object.
		 */
		return apply_filters( 'woocommerce_sort_fees_callback', $a-&gt;amount &gt; $b-&gt;amount ? -1 : 1, $a, $b );
	}

	/**
	 * Generate a unique ID for the fee being added.
	 *
	 * @param string $fee Fee object.
	 * @return string fee key.
	 */
	private function generate_id( $fee ) {
		return sanitize_title( $fee-&gt;name );
	}
}
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