woocommerce/includes/wc-notice-functions.php

<?php
/**
 * WooCommerce Message Functions
 *
 * Functions for error/message handling and display.
 *
 * @author 		WooThemes
 * @category 	Core
 * @package 	WooCommerce/Functions
 * @version     2.1.0
 */

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

/**
 * Get the count of notices added, either for all notices (default) or for one particular notice type specified
 * by $notice_type.
 *
 * @param  string $notice_type The name of the notice type - either error, success or notice. [optional]
 * @return int
 */
function wc_notice_count( $notice_type = '' ) {

	$notice_count = 0;
	$all_notices  = WC()->session->get( 'wc_notices', array() );

	if ( isset( $all_notices[$notice_type] ) ) {

		$notice_count = absint( sizeof( $all_notices[$notice_type] ) );

	} elseif ( empty( $notice_type ) ) {

		foreach ( $all_notices as $notices ) {
			$notice_count += absint( sizeof( $all_notices ) );
		}

	}

	return $notice_count;
}

/**
 * Add and store a notice
 *
 * @param  string $message The text to display in the notice.
 * @param  string $notice_type The singular name of the notice type - either error, success or notice. [optional]
 */
function wc_add_notice( $message, $notice_type = 'success' ) {

	$notices = WC()->session->get( 'wc_notices', array() );

	// Backward compatibility
	if ( 'success' === $notice_type )
		$message = apply_filters( 'woocommerce_add_message', $message );

	$notices[$notice_type][] = apply_filters( 'woocommerce_add_' . $notice_type, $message );

	WC()->session->set( 'wc_notices', $notices );
}

/**
 * Unset all notices
 *
 * @since 2.1
 */
function wc_clear_notices() {
	WC()->session->set( 'wc_notices', null );
}

/**
 * Prints messages and errors which are stored in the session, then clears them.
 *
 * @since 2.1
 */
function wc_print_notices() {

	$all_notices  = WC()->session->get( 'wc_notices', array() );
	$notice_types = apply_filters( 'woocommerce_notice_types', array( 'error', 'message', 'notice' ) );

	foreach ( $notice_types as $notice_type ) {
		if ( wc_notice_count( $notice_type ) > 0 ) {
			woocommerce_get_template( "notices/{$notice_type}.php", array(
				"{$notice_type}s" => $all_notices[$notice_type]
			) );
		}
	}

	wc_clear_notices();
}
add_action( 'woocommerce_before_shop_loop', 'wc_print_notices', 10 );
add_action( 'woocommerce_before_single_product', 'wc_print_notices', 10 );

/**
 * Returns all queued notices, optionally filtered by a notice type.
 *
 * @param  string $notice_type The singular name of the notice type - either error, success or notice. [optional]
 */
function wc_get_notices( $notice_type = '' ) {

	$all_notices = WC()->session->get( 'wc_notices', array() );

	if ( empty ( $notice_type ) ) {
		$notices = $all_notices;
	} elseif ( isset( $all_notices[$notice_type] ) ) {
		$notices = $all_notices[$notice_type];
	} else {
		$notices = array();
	}

	return $notices;
}