C#正則實現(xiàn)Ubb解析類的代碼

//作者:deerchao 
// http://www.unibetter.com/blogs/blogdeerchao/default.aspx 
//在不移除以上(及本條)注釋的前提下,任何人可以以任何方式使用此代碼. 

using System; 
using System.Collections.Generic; 
using System.Text; 
using System.Web; 
using System.Text.RegularExpressions; 

namespace Deerchao.Web 
{ 
    public class UbbDecoder 
    { 
        private static readonly RegexOptions options = RegexOptions.Compiled | RegexOptions.Singleline; 

        /// summary> 
        /// 解析Ubb代碼為Html代碼 
        /// /summary> 
        /// param name="ubb">Ubb代碼/param> 
        /// returns>解析得到的Html代碼/returns> 
        public static string Decode(string ubb) 
        { 
            if (string.IsNullOrEmpty(ubb)) 
                return null; 
            string result = ubb; 
            result = HttpUtility.HtmlEncode(result); 

            result = DecodeStyle(result); 
            result = DecodeFont(result); 
            result = DecodeColor(result); 
            result = DecodeImage(result); 
            result = DecodeLinks(result); 
            result = DecodeQuote(result); 
            result = DecodeAlign(result); 
            result = DecodeList(result); 
            result = DecodeHeading(result); 
            result = DecodeBlank(result); 

            return result; 
        } 

        /// summary> 
        /// 解析Ubb代碼為Html代碼,所有的鏈接為rel="nofollow" 
        /// /summary> 
        /// param name="ubb">Ubb代碼/param> 
        /// returns>解析得到的Html代碼/returns> 
        public static string DecodeNoFollow(string ubb) 
        { 
            if (string.IsNullOrEmpty(ubb)) 
                return null; 
            string result = ubb; 
            result = HttpUtility.HtmlEncode(result); 

            result = DecodeStyle(result); 
            result = DecodeFont(result); 
            result = DecodeColor(result); 
            result = DecodeImage(result); 
            result = DecodeLinksNoFollow(result); 
            result = DecodeQuote(result); 
            result = DecodeAlign(result); 
            result = DecodeList(result); 
            result = DecodeHeading(result); 
            result = DecodeBlank(result); 

            return result; 
        } 

        private static string DecodeHeading(string ubb) 
        { 
            string result = ubb; 
            result = Regex.Replace(result, @"\[h(\d)\](.*?)\[/h\1\]", "h$1>$2/h$1>", options); 
            return result; 
        } 

        private static string DecodeList(string ubb) 
        { 
            string sListFormat = "ol style=\"list-style:{0};\">$1/ol>"; 
            string result = ubb; 
            // Lists 
            result = Regex.Replace(result, @"\[\*\]([^\[]*)", "li>$1/li>", options); 
            result = Regex.Replace(result, @"\[list\]\s*(.*?)\[/list\]", "ul>$1/ul>", options); 
            result = Regex.Replace(result, @"\[list=1\]\s*(.*?)\[/list\]", string.Format(sListFormat, "decimal"), options); 
            result = Regex.Replace(result, @"\[list=i\]\s*(.*?)\[/list\]", string.Format(sListFormat, "lower-roman"), options); 
            result = Regex.Replace(result, @"\[list=I\]\s*(.*?)\[/list\]", string.Format(sListFormat, "upper-roman"), options); 
            result = Regex.Replace(result, @"\[list=a\]\s*(.*?)\[/list\]", string.Format(sListFormat, "lower-alpha"), options); 
            result = Regex.Replace(result, @"\[list=A\]\s*(.*?)\[/list\]", string.Format(sListFormat, "upper-alpha"), options); 

            return result; 
        } 

        private static string DecodeBlank(string ubb) 
        { 
            string result = ubb; 

            result = Regex.Replace(result, @"(?= ) | (?= )", "nbsp;", options); 
            result = Regex.Replace(result, @"\r\n", "br />"); 
            string[] blockTags = {"h[1-6]", "li", "list", "div", "p", "ul"}; 
            //clear br before block tags(start or end) 
            foreach (string tag in blockTags) 
            { 
                Regex r = new Regex("br />(" + tag + ")",options); 
                result = r.Replace(result, "$1"); 
                r = new Regex("br />(/" + tag + ")",options); 
                result = r.Replace(result, "$1"); 
            } 
            return result; 
        } 

        private static string DecodeAlign(string ubb) 
        { 
            string result = ubb; 

            result = Regex.Replace(result, @"\[left\](.*?)\[/left\]", "div style=\"text-align:left\">$1/div>", options); 
            result = Regex.Replace(result, @"\[right\](.*?)\[/right\]", "div style=\"text-align:right\">$1/div>", options); 
            result = Regex.Replace(result, @"\[center\](.*?)\[/center\]", "div style=\"text-align:center\">$1/div>", options); 

            return result; 
        } 

        private static string DecodeQuote(string ubb) 
        { 
            string result = ubb; 

            result = Regex.Replace(result, @"\[quote\]", "blockquote>div>", options); 
            result = Regex.Replace(result, @"\[/quote\]", "/div>/blockquote>", options); 
            return result; 
        } 

        private static string DecodeFont(string ubb) 
        { 
            string result = ubb; 

            result = Regex.Replace(result, @"\[size=([-\w]+)\](.*?)\[/size\]", "span style=\"font-size:$1\">$2/span>", options); 
            result = Regex.Replace(result, @"\[font=(.*?)\](.*?)\[/font\]", "span style=\"font-family:$1\">$2/span>", options); 
            return result; 
        } 

        private static string DecodeLinks(string ubb) 
        { 
            string result = ubb; 

            result = Regex.Replace(result, @"\[url\]www\.(.*?)\[/url\]", "a href=\"http://www.$1\">$1/a>", options); 
            result = Regex.Replace(result, @"\[url\](.*?)\[/url\]", "a href=\"$1\">$1/a>", options); 
            result = Regex.Replace(result, @"\[url=(.*?)\](.*?)\[/url\]", "a href=\"$1\" title=\"$2\">$2/a>", options); 
            result = Regex.Replace(result, @"\[email\](.*?)\[/email\]", "a href=\"mailto:$1\">$1/a>", options); 
            return result; 
        } 

        private static string DecodeLinksNoFollow(string ubb) 
        { 
            string result = ubb; 

            result = Regex.Replace(result, @"\[url\]www\.(.*?)\[/url\]", "a rel=\"nofollow\" href=\"http://www.$1\">$1/a>", options); 
            result = Regex.Replace(result, @"\[url\](.*?)\[/url\]", "a rel=\"nofollow\" href=\"$1\">$1/a>", options); 
            result = Regex.Replace(result, @"\[url=(.*?)\](.*?)\[/url\]", "a rel=\"nofollow\" href=\"$1\" title=\"$2\">$2/a>", options); 
            result = Regex.Replace(result, @"\[email\](.*?)\[/email\]", "a href=\"mailto:$1\">$1/a>", options); 
            return result; 
        } 

        private static string DecodeImage(string ubb) 
        { 
            string result = ubb; 

            result = Regex.Replace(result, @"\[hr\]", "hr />", options); 
            result = Regex.Replace(result, @"\[img\](.+?)\[/img\]", "img src=\"$1\" alt=\"\" />", options); 
            result = Regex.Replace(result, @"\[img=(\d+)x(\d+)\](.+?)\[/img\]", "img src=\"$3\" style=\"width:$1px;height:$2px\" alt=\"\" />", options); 

            return result; 
        } 

        private static string DecodeColor(string ubb) 
        { 
            string result = ubb; 
            result = Regex.Replace(result, @"\[color=(#?\w+?)\](.+?)\[/color\]", "span style=\"color:$1\">$2/span>",options); 

            return result; 
        } 

        private static string DecodeStyle(string ubb) 
        { 
            string result=ubb; 
            //we don't need this for perfomance and other consideration: 
            //(table[^>]*>(?>table[^>]*>(?Depth>)|/table>(?-Depth>)|.)+(?(Depth)(?!))/table>) 
            result = Regex.Replace(result, @"\[[b]\](.*?)\[/[b]\]", "strong>$1/strong>", options); 
            result = Regex.Replace(result, @"\[[u]\](.*?)\[/[u]\]", "span style=\"text-decoration:underline\">$1/span>", options); 
            result = Regex.Replace(result, @"\[[i]\](.*?)\[/[i]\]", "i>$1/i>", options); 

            return result; 
        } 
    } 
}