woocommerce/includes/widgets/class-wc-widget-cart.php

<?php
/**
 * Shopping Cart Widget
 *
 * Displays shopping cart widget
 *
 * @author   WooThemes
 * @category Widgets
 * @package  WooCommerce/Widgets
 * @version  2.3.0
 * @extends  WC_Widget
 */

if ( ! defined( 'ABSPATH' ) ) {
	exit; // Exit if accessed directly
}

class WC_Widget_Cart extends WC_Widget {

	/**
	 * Constructor
	 */
	public function __construct() {
		$this->widget_cssclass    = 'woocommerce widget_shopping_cart';
		$this->widget_description = __( "Display the user's Cart in the sidebar.", 'woocommerce' );
		$this->widget_id          = 'woocommerce_widget_cart';
		$this->widget_name        = __( 'WooCommerce Cart', 'woocommerce' );
		$this->settings           = array(
			'title'  => array(
				'type'  => 'text',
				'std'   => __( 'Cart', 'woocommerce' ),
				'label' => __( 'Title', 'woocommerce' )
			),
			'hide_if_empty' => array(
				'type'  => 'checkbox',
				'std'   => 0,
				'label' => __( 'Hide if cart is empty', 'woocommerce' )
			)
		);

		parent::__construct();
	}

	/**
	 * widget function.
	 *
	 * @see WP_Widget
	 *
	 * @param array $args
	 * @param array $instance
	 *
	 * @return void
	 */
	public function widget( $args, $instance ) {
		if ( is_cart() || is_checkout() ) {
			return;
		}

		$hide_if_empty = empty( $instance['hide_if_empty'] ) ? 0 : 1;

		$this->widget_start( $args, $instance );

		if ( $hide_if_empty ) {
			echo '<div class="hide_cart_widget_if_empty">';
		}

		// Insert cart widget placeholder - code in woocommerce.js will update this on page load
		echo '<div class="widget_shopping_cart_content"></div>';

		if ( $hide_if_empty ) {
			echo '</div>';
		}

		$this->widget_end( $args );
	}
}