TextiLite - Another lightweight version of Textile

[eluser]evanwalsh[/eluser]
I decided to make a version of Textile that only supported a small set of HTML tags because I needed it for a forum app I'm making. Here's the code for the library:

Code:

<?php if (!defined('BASEPATH')) exit('No direct script access allowed');

class TextiLite{
    
    /*
        TextiLite:
            A lightweight version of Textile built with PHP by Evan Walsh
            Version 001

        Based on the work of:
            http://codeigniter.com/wiki/BBCode_Helper/
            http://ellislab.com/forums/viewthread/69615/
            
        Supports:
            <br/> by the way of newline
            *Text* => <strong>Text</strong>
            _Text_ => <em>Text</em>
            !http://image.url! => <img src="http://image.url"/>
            "Text":http://text.url => <a href="http://text.url" title="Text">Text</a>
    */

    function paragraph($text){
        $paragraphs = explode("\n\n", $text);
        $output = null;
        foreach($paragraphs as $paragraph) {
            $output .= "\n<p>".$paragraph."</p>\n";
        }
        return $output;
    }

    function textile($text = null){
        $regex = array(
            '/(.+)\n(.+)/',
            '/\*([^\*]+)\*/',
            '/\_([^\*]+)\_/',
            '/(!)((?:http|https)(?::\\/{2}[\\w]+)(?:[\\/|\\.]?)(?:[^\\s"]*))(!)/',
            '/(")(.*?)(").*?((?:http|https)(?::\\/{2}[\\w]+)(?:[\\/|\\.]?)(?:[^\\s"]*))/',
        );
        $replace = array(
            "$1<br/>$2",
            "<strong>$1</strong>",
            "<em>$1</em>",
            "<img src=\"$2\"/>",
            "<a href=\"$4\" title=\"$2\">$2</a>",
        );
        return preg_replace($regex,$replace,$text);
    }
    
    function process($text){
        $text = strip_tags($text);
        $text = $this->paragraph($text);
        $text = $this->textile($text);
        return $text;
    }

}

?&gt;

Installation:
Copy the above code into a file named Textilite.php in your app's libraries folder

Usage:

Code:

$this->load->library("textilite");
echo $this->textilite->process("*Test*\n\n_Test_");

This would render:

Code:

<p><strong>Test</strong></p>

<p><em>Test</em></p>

Tell me what you think. I have encountered some errors and I plan on fixing them very, very soon.