/app/code/core/Mage/Core/Block/Messages.php

<?php
/**
 * Magento
 *
 * NOTICE OF LICENSE
 *
 * This source file is subject to the Open Software License (OSL 3.0)
 * that is bundled with this package in the file LICENSE.txt.
 * It is also available through the world-wide-web at this URL:
 * http://opensource.org/licenses/osl-3.0.php
 * If you did not receive a copy of the license and are unable to
 * obtain it through the world-wide-web, please send an email
 * to license@magento.com so we can send you a copy immediately.
 *
 * DISCLAIMER
 *
 * Do not edit or add to this file if you wish to upgrade Magento to newer
 * versions in the future. If you wish to customize Magento for your
 * needs please refer to http://www.magento.com for more information.
 *
 * @category    Mage
 * @package     Mage_Core
 * @copyright  Copyright (c) 2006-2016 X.commerce, Inc. and affiliates (http://www.magento.com)
 * @license    http://opensource.org/licenses/osl-3.0.php  Open Software License (OSL 3.0)
 */

/**
 * Messages block
 *
 * @category   Mage
 * @package    Mage_Core
 * @author      Magento Core Team <core@magentocommerce.com>
 */
class Mage_Core_Block_Messages extends Mage_Core_Block_Template
{
    /**
     * Messages collection
     *
     * @var Mage_Core_Model_Message_Collection
     */
    protected $_messages;

    /**
     * Store first level html tag name for messages html output
     *
     * @var string
     */
    protected $_messagesFirstLevelTagName = 'ul';

    /**
     * Store second level html tag name for messages html output
     *
     * @var string
     */
    protected $_messagesSecondLevelTagName = 'li';

    /**
     * Store content wrapper html tag name for messages html output
     *
     * @var string
     */
    protected $_messagesContentWrapperTagName = 'span';

    /**
     * Flag which require message text escape
     *
     * @var bool
     */
    protected $_escapeMessageFlag = false;

    /**
     * Storage for used types of message storages
     *
     * @var array
     */
    protected $_usedStorageTypes = array('core/session');

    public function _prepareLayout()
    {
        $this->addMessages(Mage::getSingleton('core/session')->getMessages(true));
        parent::_prepareLayout();
    }

    /**
     * Set message escape flag
     * @param bool $flag
     * @return Mage_Core_Block_Messages
     */
    public function setEscapeMessageFlag($flag)
    {
        $this->_escapeMessageFlag = $flag;
        return $this;
    }

    /**
     * Set messages collection
     *
     * @param   Mage_Core_Model_Message_Collection $messages
     * @return  Mage_Core_Block_Messages
     */
    public function setMessages(Mage_Core_Model_Message_Collection $messages)
    {
        $this->_messages = $messages;
        return $this;
    }

    /**
     * Add messages to display
     *
     * @param Mage_Core_Model_Message_Collection $messages
     * @return Mage_Core_Block_Messages
     */
    public function addMessages(Mage_Core_Model_Message_Collection $messages)
    {
        foreach ($messages->getItems() as $message) {
            $this->getMessageCollection()->add($message);
        }
        return $this;
    }

    /**
     * Retrieve messages collection
     *
     * @return Mage_Core_Model_Message_Collection
     */
    public function getMessageCollection()
    {
        if (!($this->_messages instanceof Mage_Core_Model_Message_Collection)) {
            $this->_messages = Mage::getModel('core/message_collection');
        }
        return $this->_messages;
    }

    /**
     * Adding new message to message collection
     *
     * @param   Mage_Core_Model_Message_Abstract $message
     * @return  Mage_Core_Block_Messages
     */
    public function addMessage(Mage_Core_Model_Message_Abstract $message)
    {
        $this->getMessageCollection()->add($message);
        return $this;
    }

    /**
     * Adding new error message
     *
     * @param   string $message
     * @return  Mage_Core_Block_Messages
     */
    public function addError($message)
    {
        $this->addMessage(Mage::getSingleton('core/message')->error($message));
        return $this;
    }

    /**
     * Adding new warning message
     *
     * @param   string $message
     * @return  Mage_Core_Block_Messages
     */
    public function addWarning($message)
    {
        $this->addMessage(Mage::getSingleton('core/message')->warning($message));
        return $this;
    }

    /**
     * Adding new nitice message
     *
     * @param   string $message
     * @return  Mage_Core_Block_Messages
     */
    public function addNotice($message)
    {
        $this->addMessage(Mage::getSingleton('core/message')->notice($message));
        return $this;
    }

    /**
     * Adding new success message
     *
     * @param   string $message
     * @return  Mage_Core_Block_Messages
     */
    public function addSuccess($message)
    {
        $this->addMessage(Mage::getSingleton('core/message')->success($message));
        return $this;
    }

    /**
     * Retrieve messages array by message type
     *
     * @param   string $type
     * @return  array
     */
    public function getMessages($type=null)
    {
        return $this->getMessageCollection()->getItems($type);
    }

    /**
     * Retrieve messages in HTML format
     *
     * @param   string $type
     * @return  string
     */
    public function getHtml($type=null)
    {
        $html = '<' . $this->_messagesFirstLevelTagName . ' id="admin_messages">';
        foreach ($this->getMessages($type) as $message) {
            $html.= '<' . $this->_messagesSecondLevelTagName . ' class="'.$message->getType().'-msg">'
                . ($this->_escapeMessageFlag) ? $this->escapeHtml($message->getText()) : $message->getText()
                . '</' . $this->_messagesSecondLevelTagName . '>';
        }
        $html .= '</' . $this->_messagesFirstLevelTagName . '>';
        return $html;
    }

    /**
     * Retrieve messages in HTML format grouped by type
     *
     * @param   string $type
     * @return  string
     */
    public function getGroupedHtml()
    {
        $types = array(
            Mage_Core_Model_Message::ERROR,
            Mage_Core_Model_Message::WARNING,
            Mage_Core_Model_Message::NOTICE,
            Mage_Core_Model_Message::SUCCESS
        );
        $html = '';
        foreach ($types as $type) {
            if ( $messages = $this->getMessages($type) ) {
                if ( !$html ) {
                    $html .= '<' . $this->_messagesFirstLevelTagName . ' class="messages">';
                }
                $html .= '<' . $this->_messagesSecondLevelTagName . ' class="' . $type . '-msg">';
                $html .= '<' . $this->_messagesFirstLevelTagName . '>';

                foreach ( $messages as $message ) {
                    $html.= '<' . $this->_messagesSecondLevelTagName . '>';
                    $html.= '<' . $this->_messagesContentWrapperTagName . '>';
                    $html.= ($this->_escapeMessageFlag) ? $this->escapeHtml($message->getText()) : $message->getText();
                    $html.= '</' . $this->_messagesContentWrapperTagName . '>';
                    $html.= '</' . $this->_messagesSecondLevelTagName . '>';
                }
                $html .= '</' . $this->_messagesFirstLevelTagName . '>';
                $html .= '</' . $this->_messagesSecondLevelTagName . '>';
            }
        }
        if ( $html) {
            $html .= '</' . $this->_messagesFirstLevelTagName . '>';
        }
        return $html;
    }

    protected function _toHtml()
    {
        return $this->getGroupedHtml();
    }

    /**
     * Set messages first level html tag name for output messages as html
     *
     * @param string $tagName
     */
    public function setMessagesFirstLevelTagName($tagName)
    {
        $this->_messagesFirstLevelTagName = $tagName;
    }

    /**
     * Set messages first level html tag name for output messages as html
     *
     * @param string $tagName
     */
    public function setMessagesSecondLevelTagName($tagName)
    {
        $this->_messagesSecondLevelTagName = $tagName;
    }

    /**
     * Get cache key informative items
     *
     * @return array
     */
    public function getCacheKeyInfo()
    {
        return array(
            'storage_types' => serialize($this->_usedStorageTypes)
        );
    }

    /**
     * Add used storage type
     *
     * @param string $type
     */
    public function addStorageType($type)
    {
        $this->_usedStorageTypes[] = $type;
    }
}