woocommerce/shortcodes/shortcode-cart.php

<?php
/**
 * Cart Shortcode
 *
 * Used on the cart page, the cart shortcode displays the cart contents and interface for coupon codes and other cart bits and pieces.
 *
 * @author 		WooThemes
 * @category 	Shortcodes
 * @package 	WooCommerce/Shortcodes/Cart
 * @version     1.6.4
 */

/**
 * Get the cart shortcode content.
 *
 * @access public
 * @param array $atts
 * @return string
 */
function get_woocommerce_cart( $atts ) {
	global $woocommerce;
	return $woocommerce->shortcode_wrapper( 'woocommerce_cart', $atts );
}


/**
 * Output the cart shortcode.
 *
 * @access public
 * @param array $atts
 * @return void
 */
function woocommerce_cart( $atts ) {
	global $woocommerce;

	$woocommerce->nocache();

	if ( ! defined( 'WOOCOMMERCE_CART' ) ) define( 'WOOCOMMERCE_CART', true );

	// Add Discount
	if ( ! empty( $_POST['apply_coupon'] ) ) {

		if ( ! empty( $_POST['coupon_code'] ) ) {
			$woocommerce->cart->add_discount( sanitize_text_field( $_POST['coupon_code'] ) );
		} else {
			$woocommerce->add_error( __( 'Please enter a coupon code.', 'woocommerce' ) );
		}

	// Remove Discount Codes
	} elseif ( isset( $_GET['remove_discounts'] ) ) {

		$woocommerce->cart->remove_coupons( $_GET['remove_discounts'] );

	// Update Shipping
	} elseif ( ! empty( $_POST['calc_shipping'] ) && $woocommerce->verify_nonce('cart') ) {

		$validation = $woocommerce->validation();

		$woocommerce->shipping->reset_shipping();
		$woocommerce->customer->calculated_shipping( true );
		$country 	= $_POST['calc_shipping_country'];
		$state 		= $_POST['calc_shipping_state'];
		$postcode 	= $_POST['calc_shipping_postcode'];

		if ( $postcode && ! $validation->is_postcode( $postcode, $country ) ) {
			$woocommerce->add_error( __( 'Please enter a valid postcode/ZIP.', 'woocommerce' ) );
			$postcode = '';
		} elseif ( $postcode ) {
			$postcode = $validation->format_postcode( $postcode, $country );
		}

		if ( $country ) {

			// Update customer location
			$woocommerce->customer->set_location( $country, $state, $postcode );
			$woocommerce->customer->set_shipping_location( $country, $state, $postcode );
			$woocommerce->add_message(  __( 'Shipping costs updated.', 'woocommerce' ) );

		} else {

			$woocommerce->customer->set_to_base();
			$woocommerce->customer->set_shipping_to_base();
			$woocommerce->add_message(  __( 'Shipping costs updated.', 'woocommerce' ) );

		}
		
		do_action( 'woocommerce_calculated_shipping' );
	}

	// Check cart items are valid
	do_action('woocommerce_check_cart_items');

	// Calc totals
	$woocommerce->cart->calculate_totals();

	if ( sizeof( $woocommerce->cart->get_cart() ) == 0 )
		woocommerce_get_template( 'cart/empty.php' );
	else
		woocommerce_get_template( 'cart/cart.php' );

}