Showdown.as: An AS3 port of John Fraser's showdown.js

license.txt

Copyright (c) 2010, Charles Strahan
<http://www.charlesstrahan.com/>  
All rights reserved.

Original Showdown Copyright (c) 2007, John Fraser  
<http://www.attacklab.net/>  
All rights reserved.

Original Markdown copyright (c) 2004, John Gruber  
<http://daringfireball.net/>  
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are
met:

* Redistributions of source code must retain the above copyright notice,
  this list of conditions and the following disclaimer.

* Redistributions in binary form must reproduce the above copyright
  notice, this list of conditions and the following disclaimer in the
  documentation and/or other materials provided with the distribution.

* Neither the name "Markdown" nor the names of its contributors may
  be used to endorse or promote products derived from this software
  without specific prior written permission.

This software is provided by the copyright holders and contributors "as
is" and any express or implied warranties, including, but not limited
to, the implied warranties of merchantability and fitness for a
particular purpose are disclaimed. In no event shall the copyright owner
or contributors be liable for any direct, indirect, incidental, special,
exemplary, or consequential damages (including, but not limited to,
procurement of substitute goods or services; loss of use, data, or
profits; or business interruption) however caused and on any theory of
liability, whether in contract, strict liability, or tort (including
negligence or otherwise) arising in any way out of the use of this
software, even if advised of the possibility of such damage.

Showdown.as

// UPDATE: For latest code, see https://github.com/cstrahan/Showdown.as
//
// Showdown.as -- An ActionScript port of showdown.js
//
// Copyright (c) 2010 Charles Strahan.
//
// Original Showdown Copyright (c) 2007 John Fraser.
//   <http://attacklab.net/showdown/>
//
// Original Markdown Copyright (c) 2004-2005 John Gruber
//   <http://daringfireball.net/projects/markdown/>
//
// Redistributable under a BSD-style open source license.
// See license.txt for more information.
//
// Usage:
//
//   var text = "Markdown *rocks*.";
//   var html = Showdown.makeHtml(text);
//

package {

	public class Showdown
	{
		// Global hashes, used by various utility routines
		private static var g_urls:Array;
		private static var g_titles:Array;
		private static var g_html_blocks:Array;
		
		// Used to track when we're inside an ordered or unordered list
		// (see _ProcessListItems() for details):
		private static var g_list_level:Number = 0;
		
		public static function makeHtml(text:String)
		{
			// Clear the global hashes. If we don't clear these, you get conflicts
			// from other articles when generating a page which contains more than
			// one article (e.g. an index page that shows the N most recent
			// articles):
			g_urls = new Array();
			g_titles = new Array();
			g_html_blocks = new Array();
			
			// attacklab: Replace ~ with ~T
			// This lets us use tilde as an escape char to avoid md5 hashes
			// The choice of character is arbitray; anything that isn't
			// magic in Markdown will work.
			text = text.replace(/~/g,"~T");
			
			// attacklab: Replace $ with ~D
			// RegExp interprets $ as a special character
			// when it's in a replacement string
			text = text.replace(/\$/g,"~D");
			
			// Standardize line endings
			text = text.replace(/\r\n/g,"\n"); // DOS to Unix
			text = text.replace(/\r/g,"\n"); // Mac to Unix
			
			// Make sure text begins and ends with a couple of newlines:
			text = "\n\n" + text + "\n\n";
			
			// Convert all tabs to spaces.
			text = _Detab(text);
			
			// Strip any lines consisting only of spaces and tabs.
			// This makes subsequent regexen easier to write, because we can
			// match consecutive blank lines with /\n+/ instead of something
			// contorted like /[ \t]*\n+/ .
			text = text.replace(/^[ \t]+$/mg,"");
			
			// Turn block-level HTML blocks into hash entries
			text = _HashHTMLBlocks(text);
			
			// Strip link definitions, store in hashes.
			text = _StripLinkDefinitions(text);
			
			text = _RunBlockGamut(text);
			
			text = _UnescapeSpecialChars(text);
			
			// attacklab: Restore dollar signs
			text = text.replace(/~D/g,"$$");
			
			// attacklab: Restore tildes
			text = text.replace(/~T/g,"~");
			
			return text;
		}
		
		
		private static function _StripLinkDefinitions(text) {
			//
			// Strips link definitions from text, stores the URLs and titles in
			// hash references.
			//
			
			// Link defs are in the form: ^[id]: url "optional title"
			
			/*
			var text = text.replace(/
			^[ ]{0,3}\[(.+)\]:  // id = $1  attacklab: g_tab_width - 1
			[ \t]*
			\n?				// maybe *one* newline
			[ \t]*
			<?(\S+?)>?			// url = $2
			[ \t]*
			\n?				// maybe one newline
			[ \t]*
			(?:
			(\n*)				// any lines skipped = $3 attacklab: lookbehind removed
			["(]
			(.+?)				// title = $4
			[")]
			[ \t]*
			)?					// title is optional
			(?:\n+|$)
			/gm,
			function(){...});
			*/
			var text = text.replace(/^[ ]{0,3}\[(.+)\]:[ \t]*\n?[ \t]*<?(\S+?)>?[ \t]*\n?[ \t]*(?:(\n*)["(](.+?)[")][ \t]*)?(?:\n+|\Z)/gm,
				function (wholeMatch,m1,m2,m3,m4) {
					m1 = m1.toLowerCase();
					g_urls[m1] = _EncodeAmpsAndAngles(m2);  // Link IDs are case-insensitive
					if (m3) {
						// Oops, found blank lines, so it's not a title.
						// Put back the parenthetical statement we stole.
						return m3+m4;
					} else if (m4) {
						g_titles[m1] = m4.replace(/"/g,"&quot;");
					}
					
					// Completely remove the definition from the text
					return "";
				}
			);
			
			return text;
		}
		
		
		private static function _HashHTMLBlocks(text) {
			// attacklab: Double up blank lines to reduce lookaround
			text = text.replace(/\n/g,"\n\n");
			
			// Hashify HTML blocks:
			// We only want to do this for block-level HTML tags, such as headers,
			// lists, and tables. That's because we still want to wrap <p>s around
			// "paragraphs" that are wrapped in non-block-level tags, such as anchors,
			// phrase emphasis, and spans. The list of tags we're looking for is
			// hard-coded:
			var block_tags_a = "p|div|h[1-6]|blockquote|pre|table|dl|ol|ul|script|noscript|form|fieldset|iframe|math|ins|del"
			var block_tags_b = "p|div|h[1-6]|blockquote|pre|table|dl|ol|ul|script|noscript|form|fieldset|iframe|math"
			
			// First, look for nested blocks, e.g.:
			//   <div>
			//     <div>
			//     tags for inner block must be indented.
			//     </div>
			//   </div>
			//
			// The outermost tags must start at the left margin for this to match, and
			// the inner nested divs must be indented.
			// We need to do this before the next, more liberal match, because the next
			// match will start at the first `<div>` and stop at the first `</div>`.
			
			// attacklab: This regex can be expensive when it fails.
			/*
			var text = text.replace(/
			(						// save in $1
			^					// start of line  (with /m)
			<($block_tags_a)	// start tag = $2
			\b					// word break
			// attacklab: hack around khtml/pcre bug...
			[^\r]*?\n			// any number of lines, minimally matching
			</\2>				// the matching end tag
			[ \t]*				// trailing spaces/tabs
			(?=\n+)				// followed by a newline
			)						// attacklab: there are sentinel newlines at end of document
			/gm,function(){...}};
			*/
			text = text.replace(/^(<(p|div|h[1-6]|blockquote|pre|table|dl|ol|ul|script|noscript|form|fieldset|iframe|math|ins|del)\b[^\r]*?\n<\/\2>[ \t]*(?=\n+))/gm,hashElement);
			
			//
			// Now match more liberally, simply from `\n<tag>` to `</tag>\n`
			//
			
			/*
			var text = text.replace(/
			(						// save in $1
			^					// start of line  (with /m)
			<($block_tags_b)	// start tag = $2
			\b					// word break
			// attacklab: hack around khtml/pcre bug...
			[^\r]*?				// any number of lines, minimally matching
			.*</\2>				// the matching end tag
			[ \t]*				// trailing spaces/tabs
			(?=\n+)				// followed by a newline
			)						// attacklab: there are sentinel newlines at end of document
			/gm,function(){...}};
			*/
			text = text.replace(/^(<(p|div|h[1-6]|blockquote|pre|table|dl|ol|ul|script|noscript|form|fieldset|iframe|math)\b[^\r]*?.*<\/\2>[ \t]*(?=\n+)\n)/gm,hashElement);
			
			// Special case just for <hr />. It was easier to make a special case than
			// to make the other regex more complicated.  
			
			/*
			text = text.replace(/
			(						// save in $1
			\n\n				// Starting after a blank line
			[ ]{0,3}
			(<(hr)				// start tag = $2
			\b					// word break
			([^<>])*?			// 
			\/?>)				// the matching end tag
			[ \t]*
			(?=\n{2,})			// followed by a blank line
			)
			/g,hashElement);
			*/
			text = text.replace(/(\n[ ]{0,3}(<(hr)\b([^<>])*?\/?>)[ \t]*(?=\n{2,}))/g,hashElement);
			
			// Special case for standalone HTML comments:
			
			/*
			text = text.replace(/
			(						// save in $1
			\n\n				// Starting after a blank line
			[ ]{0,3}			// attacklab: g_tab_width - 1
			<!
			(--[^\r]*?--\s*)+
			>
			[ \t]*
			(?=\n{2,})			// followed by a blank line
			)
			/g,hashElement);
			*/
			text = text.replace(/(\n\n[ ]{0,3}<!(--[^\r]*?--\s*)+>[ \t]*(?=\n{2,}))/g,hashElement);
			
			// PHP and ASP-style processor instructions (<?...?> and <%...%>)
			
			/*
			text = text.replace(/
			(?:
			\n\n				// Starting after a blank line
			)
			(						// save in $1
			[ ]{0,3}			// attacklab: g_tab_width - 1
			(?:
			<([?%])			// $2
			[^\r]*?
			\2>
			)
			[ \t]*
			(?=\n{2,})			// followed by a blank line
			)
			/g,hashElement);
			*/
			text = text.replace(/(?:\n\n)([ ]{0,3}(?:<([?%])[^\r]*?\2>)[ \t]*(?=\n{2,}))/g,hashElement);
			
			// attacklab: Undo double lines (see comment at top of this function)
			text = text.replace(/\n\n/g,"\n");
			return text;
		}
		
		private static function hashElement(wholeMatch,m1) {
			var blockText = m1;
			
			// Undo double lines
			blockText = blockText.replace(/\n\n/g,"\n");
			blockText = blockText.replace(/^\n/,"");
			
			// strip trailing blank lines
			blockText = blockText.replace(/\n+$/g,"");
			
			// Replace the element text with a marker ("~KxK" where x is its key)
			blockText = "\n\n~K" + (g_html_blocks.push(blockText)-1) + "K\n\n";
			
			return blockText;
		};
		
		private static function _RunBlockGamut(text) {
			//
			// These are all the transformations that form block-level
			// tags like paragraphs, headers, and list items.
			//
			text = _DoHeaders(text);
			
			// Do Horizontal Rules:
			var key = hashBlock("<hr />");
			text = text.replace(/^[ ]{0,2}([ ]?\*[ ]?){3,}[ \t]*$/gm,key);
			text = text.replace(/^[ ]{0,2}([ ]?\-[ ]?){3,}[ \t]*$/gm,key);
			text = text.replace(/^[ ]{0,2}([ ]?\_[ ]?){3,}[ \t]*$/gm,key);
			
			text = _DoLists(text);
			text = _DoCodeBlocks(text);
			text = _DoBlockQuotes(text);
			
			// We already ran _HashHTMLBlocks() before, in Markdown(), but that
			// was to escape raw HTML in the original Markdown source. This time,
			// we're escaping the markup we've just created, so that we don't wrap
			// <p> tags around block-level tags.
			text = _HashHTMLBlocks(text);
			text = _FormParagraphs(text);
			
			return text;
		}
		
		
		private static function _RunSpanGamut(text) {
			//
			// These are all the transformations that occur *within* block-level
			// tags like paragraphs, headers, and list items.
			//
			
			text = _DoCodeSpans(text);
			text = _EscapeSpecialCharsWithinTagAttributes(text);
			text = _EncodeBackslashEscapes(text);
			
			// Process anchor and image tags. Images must come first,
			// because ![foo][f] looks like an anchor.
			text = _DoImages(text);
			text = _DoAnchors(text);
			
			// Make links out of things like `<http://example.com/>`
			// Must come after _DoAnchors(), because you can use < and >
			// delimiters in inline links like [this](<url>).
			text = _DoAutoLinks(text);
			text = _EncodeAmpsAndAngles(text);
			text = _DoItalicsAndBold(text);
			
			// Do hard breaks:
			text = text.replace(/  +\n/g," <br />\n");
			
			return text;
		}
		
		private static function _EscapeSpecialCharsWithinTagAttributes(text) {
			//
			// Within tags -- meaning between < and > -- encode [\ ` * _] so they
			// don't conflict with their use in Markdown for code, italics and strong.
			//
			
			// Build a regex to find HTML tags and comments.  See Friedl's 
			// "Mastering Regular Expressions", 2nd Ed., pp. 200-201.
			var regex = /(<[a-z\/!$]("[^"]*"|'[^']*'|[^'">])*>|<!(--.*?--\s*)+>)/gi;
			
			text = text.replace(regex, function(wholeMatch) {
				var tag = wholeMatch.replace(/(.)<\/?code>(?=.)/g,"$1`");
				tag = escapeCharacters(tag,"\\`*_");
				return tag;
			});
			
			return text;
		}
		
		private static function _DoAnchors(text) {
			//
			// Turn Markdown link shortcuts into XHTML <a> tags.
			//
			//
			// First, handle reference-style links: [link text] [id]
			//
			
			/*
			text = text.replace(/
			(							// wrap whole match in $1
			\[
			(
			(?:
			\[[^\]]*\]		// allow brackets nested one level
			|
			[^\[]			// or anything else
			)*
			)
			\]
			
			[ ]?					// one optional space
			(?:\n[ ]*)?				// one optional newline followed by spaces
			
			\[
			(.*?)					// id = $3
			\]
			)()()()()					// pad remaining backreferences
			/g,_DoAnchors_callback);
			*/
			text = text.replace(/(\[((?:\[[^\]]*\]|[^\[\]])*)\][ ]?(?:\n[ ]*)?\[(.*?)\])()()()()/g,writeAnchorTag);
			
			//
			// Next, inline-style links: [link text](url "optional title")
			//
			
			/*
			text = text.replace(/
			(						// wrap whole match in $1
			\[
			(
			(?:
			\[[^\]]*\]	// allow brackets nested one level
			|
			[^\[\]]			// or anything else
			)
			)
			\]
			\(						// literal paren
			[ \t]*
			()						// no id, so leave $3 empty
			<?(.*?)>?				// href = $4
			[ \t]*
			(						// $5
			(['"])				// quote char = $6
			(.*?)				// Title = $7
			\6					// matching quote
			[ \t]*				// ignore any spaces/tabs between closing quote and )
			)?						// title is optional
			\)
			)
			/g,writeAnchorTag);
			*/
			text = text.replace(/(\[((?:\[[^\]]*\]|[^\[\]])*)\]\([ \t]*()<?(.*?)>?[ \t]*((['"])(.*?)\6[ \t]*)?\))/g,writeAnchorTag);
			
			//
			// Last, handle reference-style shortcuts: [link text]
			// These must come last in case you've also got [link test][1]
			// or [link test](/foo)
			//
			
			/*
			text = text.replace(/
			(		 					// wrap whole match in $1
			\[
			([^\[\]]+)				// link text = $2; can't contain '[' or ']'
			\]
			)()()()()()					// pad rest of backreferences
			/g, writeAnchorTag);
			*/
			text = text.replace(/(\[([^\[\]]+)\])()()()()()/g, writeAnchorTag);
			
			return text;
		}
		
		private static function writeAnchorTag(wholeMatch,m1,m2,m3,m4,m5,m6,m7) {
			if (m7 == undefined) m7 = "";
			var whole_match = m1;
			var link_text   = m2;
			var link_id	 = m3.toLowerCase();
			var url		= m4;
			var title	= m7;
			
			if (url == "") {
				if (link_id == "") {
					// lower-case and turn embedded newlines into spaces
					link_id = link_text.toLowerCase().replace(/ ?\n/g," ");
				}
				url = "#"+link_id;
				
				if (g_urls[link_id] != undefined) {
					url = g_urls[link_id];
					if (g_titles[link_id] != undefined) {
						title = g_titles[link_id];
					}
				}
				else {
					if (whole_match.search(/\(\s*\)$/m)>-1) {
						// Special case for explicit empty url
						url = "";
					} else {
						return whole_match;
					}
				}
			}	
			
			url = escapeCharacters(url,"*_");
			var result = "<a href=\"" + url + "\"";
			
			if (title != "") {
				title = title.replace(/"/g,"&quot;");
				title = escapeCharacters(title,"*_");
				result +=  " title=\"" + title + "\"";
			}
			
			result += ">" + link_text + "</a>";
			
			return result;
		}
		
		
		private static function _DoImages(text) {
			//
			// Turn Markdown image shortcuts into <img> tags.
			//
			
			//
			// First, handle reference-style labeled images: ![alt text][id]
			//
			
			/*
			text = text.replace(/
			(						// wrap whole match in $1
			!\[
			(.*?)				// alt text = $2
			\]
			
			[ ]?				// one optional space
			(?:\n[ ]*)?			// one optional newline followed by spaces
			
			\[
			(.*?)				// id = $3
			\]
			)()()()()				// pad rest of backreferences
			/g,writeImageTag);
			*/
			text = text.replace(/(!\[(.*?)\][ ]?(?:\n[ ]*)?\[(.*?)\])()()()()/g,writeImageTag);
			
			//
			// Next, handle inline images:  ![alt text](url "optional title")
			// Don't forget: encode * and _
			
			/*
			text = text.replace(/
			(						// wrap whole match in $1
			!\[
			(.*?)				// alt text = $2
			\]
			\s?					// One optional whitespace character
			\(					// literal paren
			[ \t]*
			()					// no id, so leave $3 empty
			<?(\S+?)>?			// src url = $4
			[ \t]*
			(					// $5
			(['"])			// quote char = $6
			(.*?)			// title = $7
			\6				// matching quote
			[ \t]*
			)?					// title is optional
			\)
			)
			/g,writeImageTag);
			*/
			text = text.replace(/(!\[(.*?)\]\s?\([ \t]*()<?(\S+?)>?[ \t]*((['"])(.*?)\6[ \t]*)?\))/g,writeImageTag);
			
			return text;
		}
		
		private static function writeImageTag(wholeMatch,m1,m2,m3,m4,m5,m6,m7) {
			var whole_match = m1;
			var alt_text   = m2;
			var link_id	 = m3.toLowerCase();
			var url		= m4;
			var title	= m7;
			
			if (!title) title = "";
			
			if (url == "") {
				if (link_id == "") {
					// lower-case and turn embedded newlines into spaces
					link_id = alt_text.toLowerCase().replace(/ ?\n/g," ");
				}
				url = "#"+link_id;
				
				if (g_urls[link_id] != undefined) {
					url = g_urls[link_id];
					if (g_titles[link_id] != undefined) {
						title = g_titles[link_id];
					}
				}
				else {
					return whole_match;
				}
			}	
			
			alt_text = alt_text.replace(/"/g,"&quot;");
			url = escapeCharacters(url,"*_");
			var result = "<img src=\"" + url + "\" alt=\"" + alt_text + "\"";
			
			// attacklab: Markdown.pl adds empty title attributes to images.
			// Replicate this bug.
			
			//if (title != "") {
			title = title.replace(/"/g,"&quot;");
			title = escapeCharacters(title,"*_");
			result +=  " title=\"" + title + "\"";
			//}
			
			result += " />";
			
			return result;
		}
		
		
		private static function _DoHeaders(text:String) {
			
			// Setext-style headers:
			//	Header 1
			//	========
			//  
			//	Header 2
			//	--------
			//
			text = text.replace(/^(.+)[ \t]*\n=+[ \t]*\n+/gm,
				function(wholeMatch,m1){return hashBlock("<h1>" + _RunSpanGamut(m1) + "</h1>");});
			
			text = text.replace(/^(.+)[ \t]*\n-+[ \t]*\n+/gm,
				function(matchFound,m1){return hashBlock("<h2>" + _RunSpanGamut(m1) + "</h2>");});
			
			// atx-style headers:
			//  # Header 1
			//  ## Header 2
			//  ## Header 2 with closing hashes ##
			//  ...
			//  ###### Header 6
			//
			
			/*
			text = text.replace(/
			^(\#{1,6})				// $1 = string of #'s
			[ \t]*
			(.+?)					// $2 = Header text
			[ \t]*
			\#*						// optional closing #'s (not counted)
			\n+
			/gm, function() {...});
			*/
			
			text = text.replace(/^(\#{1,6})[ \t]*(.+?)[ \t]*\#*\n+/gm,
				function(wholeMatch,m1,m2) {
					var h_level = m1.length;
					return hashBlock("<h" + h_level + ">" + _RunSpanGamut(m2) + "</h" + h_level + ">");
				});
			
			return text;
		}
		
		private static function _DoLists(text) {
			//
			// Form HTML ordered (numbered) and unordered (bulleted) lists.
			//
			
			// attacklab: add sentinel to hack around khtml/safari bug:
			// http://bugs.webkit.org/show_bug.cgi?id=11231
			text += "~0";
			
			// Re-usable pattern to match any entirel ul or ol list:
			
			/*
			var whole_list = /
			(									// $1 = whole list
			(								// $2
			[ ]{0,3}					// attacklab: g_tab_width - 1
			([*+-]|\d+[.])				// $3 = first list item marker
			[ \t]+
			)
			[^\r]+?
			(								// $4
			~0							// sentinel for workaround; should be $
			|
			\n{2,}
			(?=\S)
			(?!							// Negative lookahead for another list item marker
			[ \t]*
			(?:[*+-]|\d+[.])[ \t]+
			)
			)
			)/g
			*/
			var whole_list = /^(([ ]{0,3}([*+-]|\d+[.])[ \t]+)[^\r]+?(~0|\n{2,}(?=\S)(?![ \t]*(?:[*+-]|\d+[.])[ \t]+)))/gm;
			
			if (g_list_level) {
				text = text.replace(whole_list,function(wholeMatch,m1,m2) {
					var list = m1;
					var list_type = (m2.search(/[*+-]/g)>-1) ? "ul" : "ol";
					
					// Turn double returns into triple returns, so that we can make a
					// paragraph for the last item in a list, if necessary:
					list = list.replace(/\n{2,}/g,"\n\n\n");;
					var result = _ProcessListItems(list);
					
					// Trim any trailing whitespace, to put the closing `</$list_type>`
					// up on the preceding line, to get it past the current stupid
					// HTML block parser. This is a hack to work around the terrible
					// hack that is the HTML block parser.
					result = result.replace(/\s+$/,"");
					result = "<"+list_type+">" + result + "</"+list_type+">\n";
					return result;
				});
			} else {
				whole_list = /(\n\n|^\n?)(([ ]{0,3}([*+-]|\d+[.])[ \t]+)[^\r]+?(~0|\n{2,}(?=\S)(?![ \t]*(?:[*+-]|\d+[.])[ \t]+)))/g;
				text = text.replace(whole_list,function(wholeMatch,m1,m2,m3) {
					var runup = m1;
					var list = m2;
					
					var list_type = (m3.search(/[*+-]/g)>-1) ? "ul" : "ol";
					// Turn double returns into triple returns, so that we can make a
					// paragraph for the last item in a list, if necessary:
					var list = list.replace(/\n{2,}/g,"\n\n\n");;
					var result = _ProcessListItems(list);
					result = runup + "<"+list_type+">\n" + result + "</"+list_type+">\n";	
					return result;
				});
			}
			
			// attacklab: strip sentinel
			text = text.replace(/~0/,"");
			
			return text;
		}
		
		private static function _ProcessListItems(list_str) {
			//
			//  Process the contents of a single ordered or unordered list, splitting it
			//  into individual list items.
			//
			// The $g_list_level global keeps track of when we're inside a list.
			// Each time we enter a list, we increment it; when we leave a list,
			// we decrement. If it's zero, we're not in a list anymore.
			//
			// We do this because when we're not inside a list, we want to treat
			// something like this:
			//
			//    I recommend upgrading to version
			//    8. Oops, now this line is treated
			//    as a sub-list.
			//
			// As a single paragraph, despite the fact that the second line starts
			// with a digit-period-space sequence.
			//
			// Whereas when we're inside a list (or sub-list), that line will be
			// treated as the start of a sub-list. What a kludge, huh? This is
			// an aspect of Markdown's syntax that's hard to parse perfectly
			// without resorting to mind-reading. Perhaps the solution is to
			// change the syntax rules such that sub-lists must start with a
			// starting cardinal number; e.g. "1." or "a.".
			
			g_list_level++;
			
			// trim trailing blank lines:
			list_str = list_str.replace(/\n{2,}$/,"\n");
			
			// attacklab: add sentinel to emulate \z
			list_str += "~0";
			
			/*
			list_str = list_str.replace(/
			(\n)?							// leading line = $1
			(^[ \t]*)						// leading whitespace = $2
			([*+-]|\d+[.]) [ \t]+			// list marker = $3
			([^\r]+?						// list item text   = $4
			(\n{1,2}))
			(?= \n* (~0 | \2 ([*+-]|\d+[.]) [ \t]+))
			/gm, function(){...});
			*/
			list_str = list_str.replace(/(\n)?(^[ \t]*)([*+-]|\d+[.])[ \t]+([^\r]+?(\n{1,2}))(?=\n*(~0|\2([*+-]|\d+[.])[ \t]+))/gm,
				function(wholeMatch,m1,m2,m3,m4){
					var item = m4;
					var leading_line = m1;
					var leading_space = m2;
					
					if (leading_line || (item.search(/\n{2,}/)>-1)) {
						item = _RunBlockGamut(_Outdent(item));
					}
					else {
						// Recursion for sub-lists:
						item = _DoLists(_Outdent(item));
						item = item.replace(/\n$/,""); // chomp(item)
						item = _RunSpanGamut(item);
					}
					
					return  "<li>" + item + "</li>\n";
				}
			);
			
			// attacklab: strip sentinel
			list_str = list_str.replace(/~0/g,"");
			
			g_list_level--;
			return list_str;
		}
		
		
		private static function _DoCodeBlocks(text:String) {
			//
			//  Process Markdown `<pre><code>` blocks.
			//  
			
			/*
			text = text.replace(text,
			/(?:\n\n|^)
			(								// $1 = the code block -- one or more lines, starting with a space/tab
			(?:
			(?:[ ]{4}|\t)			// Lines must start with a tab or a tab-width of spaces - attacklab: g_tab_width
			.*\n+
			)+
			)
			(\n*[ ]{0,3}[^ \t\n]|(?=~0))	// attacklab: g_tab_width
			/g,function(){...});
			*/
			
			// attacklab: sentinel workarounds for lack of \A and \Z, safari\khtml bug
			text += "~0";
			
			text = text.replace(/(?:\n\n|^)((?:(?:[ ]{4}|\t).*\n+)+)(\n*[ ]{0,3}[^ \t\n]|(?=~0))/g,
				function(wholeMatch,m1,m2) {
					var codeblock = m1;
					var nextChar = m2;
					
					codeblock = _EncodeCode( _Outdent(codeblock));
					codeblock = _Detab(codeblock);
					codeblock = codeblock.replace(/^\n+/g,""); // trim leading newlines
					codeblock = codeblock.replace(/\n+$/g,""); // trim trailing whitespace
					
					codeblock = "<pre><code>" + codeblock + "\n</code></pre>";
					
					return hashBlock(codeblock) + nextChar;
				}
			);
			
			// attacklab: strip sentinel
			text = text.replace(/~0/,"");
			
			return text;
		}
		
		private static function hashBlock(text) {
			text = text.replace(/(^\n+|\n+$)/g,"");
			return "\n\n~K" + (g_html_blocks.push(text)-1) + "K\n\n";
		}
		
		
		private static function _DoCodeSpans(text:String) {
			//
			//   *  Backtick quotes are used for <code></code> spans.
			// 
			//   *  You can use multiple backticks as the delimiters if you want to
			//	 include literal backticks in the code span. So, this input:
			//	 
			//		 Just type ``foo `bar` baz`` at the prompt.
			//	 
			//	   Will translate to:
			//	 
			//		 <p>Just type <code>foo `bar` baz</code> at the prompt.</p>
			//	 
			//	There's no arbitrary limit to the number of backticks you
			//	can use as delimters. If you need three consecutive backticks
			//	in your code, use four for delimiters, etc.
			//
			//  *  You can use spaces to get literal backticks at the edges:
			//	 
			//		 ... type `` `bar` `` ...
			//	 
			//	   Turns to:
			//	 
			//		 ... type <code>`bar`</code> ...
			//
			
			/*
			text = text.replace(/
			(^|[^\\])					// Character before opening ` can't be a backslash
			(`+)						// $2 = Opening run of `
			(							// $3 = The code block
			[^\r]*?
			[^`]					// attacklab: work around lack of lookbehind
			)
			\2							// Matching closer
			(?!`)
			/gm, function(){...});
			*/
			
			text = text.replace(/(^|[^\\])(`+)([^\r]*?[^`])\2(?!`)/gm,
				function(wholeMatch,m1,m2,m3,m4) {
					var c = m3;
					c = c.replace(/^([ \t]*)/g,"");	// leading whitespace
					c = c.replace(/[ \t]*$/g,"");	// trailing whitespace
					c = _EncodeCode(c);
					return m1+"<code>"+c+"</code>";
				});
			
			return text;
		}
		
		
		private static function _EncodeCode(text:String) {
			//
			// Encode/escape certain characters inside Markdown code runs.
			// The point is that in code, these characters are literals,
			// and lose their special Markdown meanings.
			//
			// Encode all ampersands; HTML entities are not
			// entities within a Markdown code span.
			text = text.replace(/&/g,"&amp;");
			
			// Do the angle bracket song and dance:
			text = text.replace(/</g,"&lt;");
			text = text.replace(/>/g,"&gt;");
			
			// Now, escape characters that are magic in Markdown:
			text = escapeCharacters(text,"\*_{}[]\\",false);
			
			// jj the line above breaks this:
			//---
			
			//* Item
			
			//   1. Subitem
			
			//            special char: *
			//---
			
			return text;
		}
		
		
		private static function _DoItalicsAndBold(text:String) {
			
			// <strong> must go first:
			text = text.replace(/(\*\*|__)(?=\S)([^\r]*?\S[*_]*)\1/g,
				"<strong>$2</strong>");
			
			text = text.replace(/(\*|_)(?=\S)([^\r]*?\S)\1/g,
				"<em>$2</em>");
			
			return text;
		}
		
		
		private static function _DoBlockQuotes(text:String) {
			
			/*
			text = text.replace(/
			(								// Wrap whole match in $1
			(
			^[ \t]*>[ \t]?			// '>' at the start of a line
			.+\n					// rest of the first line
			(.+\n)*					// subsequent consecutive lines
			\n*						// blanks
			)+
			)
			/gm, function(){...});
			*/
			
			text = text.replace(/((^[ \t]*>[ \t]?.+\n(.+\n)*\n*)+)/gm,
				function(wholeMatch,m1) {
					var bq = m1;
					
					// attacklab: hack around Konqueror 3.5.4 bug:
					// "----------bug".replace(/^-/g,"") == "bug"
					
					bq = bq.replace(/^[ \t]*>[ \t]?/gm,"~0");	// trim one level of quoting
					
					// attacklab: clean up hack
					bq = bq.replace(/~0/g,"");
					
					bq = bq.replace(/^[ \t]+$/gm,"");		// trim whitespace-only lines
					bq = _RunBlockGamut(bq);				// recurse
					
					bq = bq.replace(/(^|\n)/g,"$1  ");
					// These leading spaces screw with <pre> content, so we need to fix that:
					bq = bq.replace(
						/(\s*<pre>[^\r]+?<\/pre>)/gm,
						function(wholeMatch,m1) {
							var pre = m1;
							// attacklab: hack around Konqueror 3.5.4 bug:
							pre = pre.replace(/^  /mg,"~0");
							pre = pre.replace(/~0/g,"");
							return pre;
						});
					
					return hashBlock("<blockquote>\n" + bq + "\n</blockquote>");
				});
			return text;
		}
		
		
		private static function _FormParagraphs(text:String) {
			//
			//  Params:
			//    $text - string to process with html <p> tags
			//
			
			// Strip leading and trailing lines:
			text = text.replace(/^\n+/g,"");
			text = text.replace(/\n+$/g,"");
			
			var grafs:Array = text.split(/\n{2,}/g);
			var grafsOut:Array = new Array();
			
			//
			// Wrap <p> tags.
			//
			var end = grafs.length;
			for (var i=0; i<end; i++) {
				var str:String = grafs[i];
				
				// if this is an HTML marker, copy it
				if (str.search(/~K(\d+)K/g) >= 0) {
					grafsOut.push(str);
				}
				else if (str.search(/\S/) >= 0) {
					str = _RunSpanGamut(str);
					str = str.replace(/^([ \t]*)/g,"<p>");
					str += "</p>"
					grafsOut.push(str);
				}
				
			}
			
			//
			// Unhashify HTML blocks
			//
			end = grafsOut.length;
			for (var i=0; i<end; i++) {
				// if this is a marker for an html block...
				while (grafsOut[i].search(/~K(\d+)K/) >= 0) {
					var firstGroup:String = (/~K(\d+)K/).exec(grafsOut[i])[1];
					var blockText = g_html_blocks[firstGroup];
					blockText = blockText.replace(/\$/g,"$$$$"); // Escape any dollar signs
					grafsOut[i] = grafsOut[i].replace(/~K\d+K/,blockText);
				}
			}
			
			return grafsOut.join("\n\n");
		}
		
		
		private static function _EncodeAmpsAndAngles(text:String) {
			// Smart processing for ampersands and angle brackets that need to be encoded.
			
			// Ampersand-encoding based entirely on Nat Irons's Amputator MT plugin:
			//   http://bumppo.net/projects/amputator/
			text = text.replace(/&(?!#?[xX]?(?:[0-9a-fA-F]+|\w+);)/g,"&amp;");
			
			// Encode naked <'s
			text = text.replace(/<(?![a-z\/?\$!])/gi,"&lt;");
			
			return text;
		}
		
		
		private static function _EncodeBackslashEscapes(text:String) {
			//
			//   Parameter:  String.
			//   Returns:	The string, with after processing the following backslash
			//			   escape sequences.
			//
			
			// attacklab: The polite way to do this is with the new
			// escapeCharacters() function:
			//
			// 	text = escapeCharacters(text,"\\",true);
			// 	text = escapeCharacters(text,"`*_{}[]()>#+-.!",true);
			//
			// ...but we're sidestepping its use of the (slow) RegExp constructor
			// as an optimization for Firefox.  This function gets called a LOT.
			
			text = text.replace(/\\(\\)/g,escapeCharacters_callback);
			text = text.replace(/\\([`*_{}\[\]()>#+-.!])/g,escapeCharacters_callback);
			return text;
		}
		
		
		private static function _DoAutoLinks(text:String) {
			
			text = text.replace(/<((https?|ftp|dict):[^'">\s]+)>/gi,"<a href=\"$1\">$1</a>");
			
			// Email addresses: <[email protected]>
			
			/*
			text = text.replace(/
			<
			(?:mailto:)?
			(
			[-.\w]+
			\@
			[-a-z0-9]+(\.[-a-z0-9]+)*\.[a-z]+
			)
			>
			/gi, _DoAutoLinks_callback());
			*/
			text = text.replace(/<(?:mailto:)?([-.\w]+\@[-a-z0-9]+(\.[-a-z0-9]+)*\.[a-z]+)>/gi,
				function(wholeMatch,m1) {
					return _EncodeEmailAddress( _UnescapeSpecialChars(m1) );
				}
			);
			
			return text;
		}
		
		
		private static function _EncodeEmailAddress(addr:String) {
			//
			//  Input: an email address, e.g. "[email protected]"
			//
			//  Output: the email address as a mailto link, with each character
			//	of the address encoded as either a decimal or hex entity, in
			//	the hopes of foiling most address harvesting spam bots. E.g.:
			//
			//	<a href="&#x6D;&#97;&#105;&#108;&#x74;&#111;:&#102;&#111;&#111;&#64;&#101;
			//	   x&#x61;&#109;&#x70;&#108;&#x65;&#x2E;&#99;&#111;&#109;">&#102;&#111;&#111;
			//	   &#64;&#101;x&#x61;&#109;&#x70;&#108;&#x65;&#x2E;&#99;&#111;&#109;</a>
			//
			//  Based on a filter by Matthew Wickline, posted to the BBEdit-Talk
			//  mailing list: <http://tinyurl.com/yu7ue>
			//
			
			// attacklab: why can't javascript speak hex?
			function char2hex(ch:String) {
				var hexDigits = '0123456789ABCDEF';
				var dec = ch.charCodeAt(0);
				return(hexDigits.charAt(dec>>4) + hexDigits.charAt(dec&15));
			}
			
			var encode = [
				function(ch){return "&#"+ch.charCodeAt(0)+";";},
				function(ch){return "&#x"+char2hex(ch)+";";},
				function(ch){return ch;}
			];
			
			addr = "mailto:" + addr;
			
			addr = addr.replace(/./g, function(ch) {
				if (ch == "@") {
					// this *must* be encoded. I insist.
					ch = encode[Math.floor(Math.random()*2)](ch);
				} else if (ch !=":") {
					// leave ':' alone (to spot mailto: later)
					var r = Math.random();
					// roughly 10% raw, 45% hex, 45% dec
					ch =  (
						r > .9  ?	encode[2](ch)   :
						r > .45 ?	encode[1](ch)   :
						encode[0](ch)
					);
				}
				return ch;
			});
			
			addr = "<a href=\"" + addr + "\">" + addr + "</a>";
			addr = addr.replace(/">.+:/g,"\">"); // strip the mailto: from the visible part
			
			return addr;
		}
		
		
		private static function _UnescapeSpecialChars(text:String) {
			//
			// Swap back in all the special characters we've hidden.
			//
			text = text.replace(/~E(\d+)E/g,
				function(wholeMatch,m1) {
					var charCodeToReplace = parseInt(m1);
					return String.fromCharCode(charCodeToReplace);
				}
			);
			return text;
		}
		
		
		private static function _Outdent(text:String) {
			//
			// Remove one level of line-leading tabs or spaces
			//
			
			// attacklab: hack around Konqueror 3.5.4 bug:
			// "----------bug".replace(/^-/g,"") == "bug"
			
			text = text.replace(/^(\t|[ ]{1,4})/gm,"~0"); // attacklab: g_tab_width
			
			// attacklab: clean up hack
			text = text.replace(/~0/g,"")
			
			return text;
		}
		
		private static function _Detab(text:String) {
			// attacklab: Detab's completely rewritten for speed.
			// In perl we could fix it by anchoring the regexp with \G.
			// In javascript we're less fortunate.
			
			// expand first n-1 tabs
			text = text.replace(/\t(?=\t)/g,"    "); // attacklab: g_tab_width
			
			// replace the nth with two sentinels
			text = text.replace(/\t/g,"~A~B");
			
			// use the sentinel to anchor our regex so it doesn't explode
			text = text.replace(/~B(.+?)~A/g,
				function(wholeMatch,m1,m2) {
					var leadingText = m1;
					var numSpaces = 4 - leadingText.length % 4;  // attacklab: g_tab_width
					
					// there *must* be a better way to do this:
					for (var i=0; i<numSpaces; i++) leadingText+=" ";
					
					return leadingText;
				}
			);
			
			// clean up sentinels
			text = text.replace(/~A/g,"    ");  // attacklab: g_tab_width
			text = text.replace(/~B/g,"");
			
			return text;
		}
		
		
		//
		//  attacklab: Utility functions
		//
		
		
		private static function escapeCharacters(text:String, charsToEscape, afterBackslash = false):String {
			// First we have to escape the escape characters so that
			// we can build a character class out of them
			var regexString = "([" + charsToEscape.replace(/([\[\]\\])/g,"\\$1") + "])";
			
			if (afterBackslash) {
				regexString = "\\\\" + regexString;
			}
			
			var regex = new RegExp(regexString,"g");
			text = text.replace(regex,escapeCharacters_callback);
			
			return text;
		}
		
		private static function escapeCharacters_callback(wholeMatch,m1) {
			var charCodeToEscape = m1.charCodeAt(0);
			return "~E"+charCodeToEscape+"E";
		}
	}// end of Showdown.converter
}

nice job！

How do you get this to work on a TextField already placed on the stage (in the actual Flash Pro IDE)? Do you need to setup the properties of the TextField in any special way? Embed all the font family "styles" (and if so, how do you refer to all of them on a TextField? the dropdown menu only lets you pick one).

Maybe I didn't understand what this library was for. Is it intended to be use on HTML outside of Flash?