C# 写的 BBCode 解析器

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

namespace NetCoders.Helpers
{
    /// <summary>
    /// BBCode Helper allows formatting of text
    /// without the need to use html
    /// </summary>
    public class BBCodeHelper
    {
	    #region Helper Classes
	    interface IHtmlFormatter
	    {
		    string Format(string data);
	    }

	    protected class RegexFormatter : IHtmlFormatter
	    {
		    private string _replace;
		    private Regex _regex;

		    public RegexFormatter(string pattern, string replace)
			    : this(pattern, replace, true)
		    {

		    }

		    public RegexFormatter(string pattern, string replace, bool ignoreCase)
		    {
			    RegexOptions options = RegexOptions.Compiled;

			    if (ignoreCase)
			    {
				    options |= RegexOptions.IgnoreCase;
			    }

			    _replace = replace;
			    _regex = new Regex(pattern, options);
		    }

		    public string Format(string data)
		    {
			    return _regex.Replace(data, _replace);
		    }
	    }

	    protected class SearchReplaceFormatter : IHtmlFormatter
	    {
		    private string _pattern;
		    private string _replace;

		    public SearchReplaceFormatter(string pattern, string replace)
		    {
			    _pattern = pattern;
			    _replace = replace;
		    }

		    public string Format(string data)
		    {
			    return data.Replace(_pattern, _replace);
		    }
	    }
	    #endregion

	    #region BBCode
	    static List<IHtmlFormatter> _formatters;

	    static BBCodeHelper()
	    {
		    _formatters = new List<IHtmlFormatter>();

		    _formatters.Add(new RegexFormatter(@"<(.|\n)*?>", string.Empty));

		    _formatters.Add(new SearchReplaceFormatter("\r", ""));
		    _formatters.Add(new SearchReplaceFormatter("\n\n", "</p><p>"));
		    _formatters.Add(new SearchReplaceFormatter("\n", "<br />"));

		    _formatters.Add(new RegexFormatter(@"\[b(?:\s*)\]((.|\n)*?)\[/b(?:\s*)\]", "<b>$1</b>"));
		    _formatters.Add(new RegexFormatter(@"\[i(?:\s*)\]((.|\n)*?)\[/i(?:\s*)\]", "<i>$1</i>"));
		    _formatters.Add(new RegexFormatter(@"\[s(?:\s*)\]((.|\n)*?)\[/s(?:\s*)\]", "<strike>$1</strike>"));

		    _formatters.Add(new RegexFormatter(@"\[left(?:\s*)\]((.|\n)*?)\[/left(?:\s*)]", "<div style=\"text-align:left\">$1</div>"));
		    _formatters.Add(new RegexFormatter(@"\[center(?:\s*)\]((.|\n)*?)\[/center(?:\s*)]", "<div style=\"text-align:center\">$1</div>"));
		    _formatters.Add(new RegexFormatter(@"\[right(?:\s*)\]((.|\n)*?)\[/right(?:\s*)]", "<div style=\"text-align:right\">$1</div>"));

		    string quoteStart = "<blockquote><b>$1 said:</b></p><p>";
		    string quoteEmptyStart = "<blockquote>";
		    string quoteEnd = "</blockquote>";

		    _formatters.Add(new RegexFormatter(@"\[quote=((.|\n)*?)(?:\s*)\]", quoteStart));
		    _formatters.Add(new RegexFormatter(@"\[quote(?:\s*)\]", quoteEmptyStart));
		    _formatters.Add(new RegexFormatter(@"\[/quote(?:\s*)\]", quoteEnd));

		    _formatters.Add(new RegexFormatter(@"\[url(?:\s*)\]www\.(.*?)\[/url(?:\s*)\]", "<a class=\"bbcode-link\" href=\"http://www.$1\" target=\"_blank\" title=\"$1\">$1</a>"));
		    _formatters.Add(new RegexFormatter(@"\[url(?:\s*)\]((.|\n)*?)\[/url(?:\s*)\]", "<a class=\"bbcode-link\" href=\"$1\" target=\"_blank\" title=\"$1\">$1</a>"));
		    _formatters.Add(new RegexFormatter(@"\[url=""((.|\n)*?)(?:\s*)""\]((.|\n)*?)\[/url(?:\s*)\]", "<a class=\"bbcode-link\" href=\"$1\" target=\"_blank\" title=\"$1\">$3</a>"));
		    _formatters.Add(new RegexFormatter(@"\[url=((.|\n)*?)(?:\s*)\]((.|\n)*?)\[/url(?:\s*)\]", "<a class=\"bbcode-link\" href=\"$1\" target=\"_blank\" title=\"$1\">$3</a>"));
		    _formatters.Add(new RegexFormatter(@"\[link(?:\s*)\]((.|\n)*?)\[/link(?:\s*)\]", "<a class=\"bbcode-link\" href=\"$1\" target=\"_blank\" title=\"$1\">$1</a>"));
		    _formatters.Add(new RegexFormatter(@"\[link=((.|\n)*?)(?:\s*)\]((.|\n)*?)\[/link(?:\s*)\]", "<a class=\"bbcode-link\" href=\"$1\" target=\"_blank\" title=\"$1\">$3</a>"));

		    _formatters.Add(new RegexFormatter(@"\[img(?:\s*)\]((.|\n)*?)\[/img(?:\s*)\]", "<img src=\"$1\" border=\"0\" alt=\"\" />"));
		    _formatters.Add(new RegexFormatter(@"\[img align=((.|\n)*?)(?:\s*)\]((.|\n)*?)\[/img(?:\s*)\]", "<img src=\"$3\" border=\"0\" align=\"$1\" alt=\"\" />"));
		    _formatters.Add(new RegexFormatter(@"\[img=((.|\n)*?)x((.|\n)*?)(?:\s*)\]((.|\n)*?)\[/img(?:\s*)\]", "<img width=\"$1\" height=\"$3\" src=\"$5\" border=\"0\" alt=\"\" />"));

		    _formatters.Add(new RegexFormatter(@"\[color=((.|\n)*?)(?:\s*)\]((.|\n)*?)\[/color(?:\s*)\]", "<span style=\"color=$1;\">$3</span>"));

		    _formatters.Add(new RegexFormatter(@"\[hr(?:\s*)\]", "<hr />"));

		    _formatters.Add(new RegexFormatter(@"\[email(?:\s*)\]((.|\n)*?)\[/email(?:\s*)\]", "<a href=\"mailto:$1\">$1</a>"));

		    _formatters.Add(new RegexFormatter(@"\[size=((.|\n)*?)(?:\s*)\]((.|\n)*?)\[/size(?:\s*)\]", "<span style=\"font-size:$1\">$3</span>"));
		    _formatters.Add(new RegexFormatter(@"\[font=((.|\n)*?)(?:\s*)\]((.|\n)*?)\[/font(?:\s*)\]", "<span style=\"font-family:$1;\">$3</span>"));
		    _formatters.Add(new RegexFormatter(@"\[align=((.|\n)*?)(?:\s*)\]((.|\n)*?)\[/align(?:\s*)\]", "<span style=\"text-align:$1;\">$3</span>"));
		    _formatters.Add(new RegexFormatter(@"\[float=((.|\n)*?)(?:\s*)\]((.|\n)*?)\[/float(?:\s*)\]", "<span style=\"float:$1;\">$3</div>"));

		    string sListFormat = "<ol class=\"bbcode-list\" style=\"list-style:{0};\">$1</ol>";

		    _formatters.Add(new RegexFormatter(@"\[\*(?:\s*)]\s*([^\[]*)", "<li>$1</li>"));
		    _formatters.Add(new RegexFormatter(@"\[list(?:\s*)\]((.|\n)*?)\[/list(?:\s*)\]", "<ul class=\"bbcode-list\">$1</ul>"));
		    _formatters.Add(new RegexFormatter(@"\[list=1(?:\s*)\]((.|\n)*?)\[/list(?:\s*)\]", string.Format(sListFormat, "decimal"), false));
		    _formatters.Add(new RegexFormatter(@"\[list=i(?:\s*)\]((.|\n)*?)\[/list(?:\s*)\]", string.Format(sListFormat, "lower-roman"), false));
		    _formatters.Add(new RegexFormatter(@"\[list=I(?:\s*)\]((.|\n)*?)\[/list(?:\s*)\]", string.Format(sListFormat, "upper-roman"), false));
		    _formatters.Add(new RegexFormatter(@"\[list=a(?:\s*)\]((.|\n)*?)\[/list(?:\s*)\]", string.Format(sListFormat, "lower-alpha"), false));
		    _formatters.Add(new RegexFormatter(@"\[list=A(?:\s*)\]((.|\n)*?)\[/list(?:\s*)\]", string.Format(sListFormat, "upper-alpha"), false));
	    }
	    #endregion

	    #region Format
	    public static string Format(string data)
	    {
		    foreach (IHtmlFormatter formatter in _formatters)
		    {
			    data = formatter.Format(data);
		    }

		    return data;
	    }
	    #endregion
    }
}