showdown.js

//
// showdown.js -- A javascript port of Markdown.
//
// Copyright (c) 2010-2011 Jarvis Badgley <http://chipersoft.com>.

// Copyright (c) 2007 John Fraser <http://www.attacklab.net/>.
//
// Original Markdown Copyright (c) 2004-2005 John Gruber
//   <http://daringfireball.net/projects/markdown/>
//
//
// Showdown usage:
//
//   var text = "Markdown *rocks*.";
//
//   var converter = new Showdown.converter();
//   var html = converter.makeHtml(text);
//
//   alert(html);
//
// Note: move the sample code to the bottom of this
// file before uncommenting it.
//

//
// Showdown namespace
//
Showdown = {};

//
// converter
//
// Wraps all "globals" so that the only thing
// exposed is makeHtml().
//
Showdown.converter = function () {
	//
	// Globals:
	//
	// Global hashes, used by various utility routines
	var g_urls;
	var g_titles;
	var g_html_blocks;

	// Used to track when we're inside an ordered or unordered list
	// (see _ProcessListItems() for details):
	var g_list_level = 0;


	this.makeHtml = function (text) {
		//
		// Main function. The order in which other subs are called here is
		// essential. Link and image substitutions need to happen before
		// _EscapeSpecialCharsWithinTagAttributes(), so that any *'s or _'s in the <a>
		// and <img> tags get encoded.
		//
		// 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 = [];
		g_titles = [];
		g_html_blocks = [];

		// 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, "~");

		// ** GFM **  Auto-link URLs and emails
		text = text.replace(/https?\:\/\/[^"\s<>]*[^.,;'">\:\s<>\)\]\!]/g, function (wholeMatch, matchIndex){
			var left = text.slice(Math.max(0,text.lastIndexOf('\n',matchIndex)), matchIndex);
			var right = text.slice(matchIndex);
			if (left.match(/<([a-z]+)\s[^>]+>?$/) && right.match(/^[^>]*>/)) {return wholeMatch;}
			return "<a href='" + wholeMatch + "'>" + wholeMatch + "</a>";
		});
		
		text = text.replace(/[a-z0-9_\-+=.]+@[a-z0-9\-]+(\.[a-z0-9\-]+)+/ig, function (wholeMatch, m1, matchIndex) {
			var left = text.slice(Math.max(0,text.lastIndexOf('\n',matchIndex)), matchIndex);
			if (left.match(/<([a-z]+)\s[^>]+>?$/) || left.match(/mailto\:$/)) {return wholeMatch;}
			return "<a href='mailto:" + wholeMatch + "'>" + wholeMatch + "</a>";
		});

		return text;
	};

	var _StripLinkDefinitions = function (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(){...});
	*/
		text = text.replace(/^[ ]{0,3}\[(.+)\]:[ \t]*\n?[ \t]*<?(\S+?)>?[ \t]*\n?[ \t]*(?:(\n*)["(](.+?)[")][ \t]*)?(?:\n+)/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;
	};

	var _HashHTMLBlocks = function (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;
	};

	var hashElement = function (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;
	};

	var _RunBlockGamut = function (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;
	};


	var _RunSpanGamut = function (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 = _DoPlaceholder(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 = _ConvertExtraSpecialCharacters(text);
		text = _DoItalicsAndBold(text);

		// Do hard breaks:
		text = text.replace(/ {2,}\n/g, " <br />\n");
				
		return text;
	};

	var _EscapeSpecialCharsWithinTagAttributes = function (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;
	};

	var _DoAnchors = function (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;
	};

	var writeAnchorTag = function (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;
		var blank_target = false;

		if (url === "") {
			if (link_id === "") {
				// lower-case and turn embedded newlines into spaces
				link_id = link_text.toLowerCase().replace(/ ?\n/g, " ");
			} else {
				if (link_id[0]=="!") {
					blank_target = true;
					link_id = link_id.substr(1);
				}
			}
			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];
				}
				if (url[0]=="!") {
					blank_target = true;
					url = url.substr(1);
				}
			}
			else {
				if (whole_match.search(/\(\s*\)$/m) > -1) {
					// Special case for explicit empty url
					url = "";
				} else {
					return whole_match;
				}
			}
		} else {
			if (url[0]=="!") {
				blank_target = true;
				url = url.substr(1);
			}
		}

		url = escapeCharacters(url, "*_");
		var result = "<a href=\"" + url + "\"";

		if (title !== "") {
			title = title.replace(/"/g, "&quot;");
			title = escapeCharacters(title, "*_");
			result += " title=\"" + title + "\"";
		}
		
		if (blank_target) {
			result += " target=\"_blank\"";
		}

		result += ">" + link_text + "</a>";

		return result;
	};

	var _DoPlaceholder = function (text) {
		text = text.replace(/(!dnd\[(.*?)\]?(?:\n[ ]*)?\])()()()()/g, placeholderTag);
		return text;
	};

	var placeholderTag = function (wholeMatch, m1, m2, m3, m4, m5, m6, m7) {
		var id = Date.now();
		html = '<div data-id="' + m2 +  '" class="placeholder_drop">';
		html += '<i class="icon-camera-retro icon-4x"></i><br> Add an image of <strong>' + m2 + '</strong></div>';
		return html;
	}

	var _DoImages = function (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;
	};

	var writeImageTag = function (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;
	};


	var _DoHeaders = function (text) {

		// 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;
	};

	// This declaration keeps Dojo compressor from outputting garbage:
	var _ProcessListItems;

	var _DoLists = function (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:
				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;
	};

	_ProcessListItems = function (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;
	};


	var _DoCodeBlocks = function (text) {
		//
		//  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;
	};

	var hashBlock = function (text) {
		text = text.replace(/(^\n+|\n+$)/g, "");
		return "\n\n~K" + (g_html_blocks.push(text) - 1) + "K\n\n";
	};


	var _DoCodeSpans = function (text) {
		//
		//   *  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>";
		});


		// Process ^^superscript^^ notation
		text = text.replace(/(^|[^\\])(\^{2})([^\r]*?[^\^]{2})\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 + "<sup>" + c + "</sup>";
		});

		// Process ,,subscript,, notation
		text = text.replace(/(^|[^\\])(,{2})([^\r]*?[^,]{2})\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 + "<sub>" + c + "</sub>";
		});

		// Process ~~strike~~ notation
		text = text.replace(/(^|[^\\])(~T~T)([^\r]*?[^~]{2})\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 + "<strike>" + c + "</strike>";
		});
		
		return text;
	};


	var _EncodeCode = function (text) {
		//
		// 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;");

		// Encode "smart" quotes
		text = text.
			replace( /\u2026/g	, '&hellip;').
			replace( /\u00AB/g	, '&laquo;'	).
			replace( /\u00BB/g	, '&raquo;'	).
			replace( /\u201C/g	, '&ldquo;'	).
			replace( /\u201D/g	, '&rdquo;'	).
			replace( /\u2018/g	, '&lsquo;'	).
			replace( /\u2019/g	, '&rsquo;'	).
			replace( /\u2014/g	, '&mdash;'	).
			replace( /\u2013/g	, '&ndash;'	).
			replace( /\u2022/g	, '&bull;'	).
			replace( /\u2122/g	, '&trade;'	).
			replace( /\u00A9/g	, '&copy;'	).
			replace( /\u00AE/g	, '&reg;'	);


		// 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;
	};


	var _DoItalicsAndBold = function (text) {

		if (true) { //eventually this will be replaced with a runtime option. But for now we're forcing it.
			text = text.replace(/(\*\*)(?=\S)([^\r]*?\S[*]*)\1/g, "<strong>$2</strong>");
			text = text.replace(/(\w)_(\w)/g, "$1~E95E$2"); // ** GFM **  "~E95E" == escaped "_"
			text = text.replace(/(\*)(?=\S)([^\r]*?\S)\1/g, "<em>$2</em>");
			text = text.replace(/(_)(?=\S)([^\r]*?\S)\1/g, "<u>$2</u>");
		} else {
			// <strong> must go first:
			text = text.replace(/(\*\*|__)(?=\S)([^\r]*?\S[*_]*)\1/g, "<strong>$2</strong>");

			text = text.replace(/(\w)_(\w)/g, "$1~E95E$2"); // ** GFM **  "~E95E" == escaped "_"
			text = text.replace(/(\*|_)(?=\S)([^\r]*?\S)\1/g, "<em>$2</em>");
		}

		return text;
	};


	var _DoBlockQuotes = function (text) {

/*
		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(/^ {2}/mg, "~0");
				pre = pre.replace(/~0/g, "");
				return pre;
			});

			return hashBlock("<blockquote>\n" + bq + "\n</blockquote>");
		});
		return text;
	};


	var _FormParagraphs = function (text) {
		//
		//  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 i;
		var grafs = text.split(/\n{2,}/g);
		var grafsOut = [];

		//
		// Wrap <p> tags.
		//
		var end = grafs.length;
		for (i = 0; i < end; i++) {
			var str = grafs[i];
			var p_tag = '<p>';

			// 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);
				
				if (str.substr(0,2)==='->') {
					if (str.substr(-5)==='&lt;-') {
						p_tag = '<p align="center">';
						str = str.slice(2,-5);
					} else {
						p_tag = '<p align="right">';
						str = str.substring(2);
					}
				}
				
				str = str.replace(/\n/g, "<br />"); // ** GFM **
				str = str.replace(/^([ \t]*)/g, p_tag);
				str += "</p>";
				grafsOut.push(str);
			}

		}

		//
		// Unhashify HTML blocks
		//
		end = grafsOut.length;
		for (i = 0; i < end; i++) {
			// if this is a marker for an html block...
			while (grafsOut[i].search(/~K(\d+)K/) >= 0) {
				var blockText = g_html_blocks[RegExp.$1];
				blockText = blockText.replace(/\$/g, "$$$$"); // Escape any dollar signs
				grafsOut[i] = grafsOut[i].replace(/~K\d+K/, blockText);
			}
		}

		return grafsOut.join("\n\n");
	};


	var _EncodeAmpsAndAngles = function (text) {
		// 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;");

		// Encode "smart" quotes
		text = text.
			replace( /\u2026/g	, '&hellip;').
			replace( /\u00AB/g	, '&laquo;'	).
			replace( /\u00BB/g	, '&raquo;'	).
			replace( /\u201C/g	, '&ldquo;'	).
			replace( /\u201D/g	, '&rdquo;'	).
			replace( /\u2018/g	, '&lsquo;'	).
			replace( /\u2019/g	, '&rsquo;'	).
			replace( /\u2014/g	, '&mdash;'	).
			replace( /\u2013/g	, '&ndash;'	).
			replace( /\u2022/g	, '&bull;'	).
			replace( /\u2122/g	, '&trade;'	).
			replace( /\u00A9/g	, '&copy;'	).
			replace( /\u00AE/g	, '&reg;'	);

		return text;
	};
	
	var _ConvertExtraSpecialCharacters = function (text) {
		// Processing to change various special character combinations into
		// common real characters.
		
		text = text.
			replace( /\.\.\./g	, '&hellip;').
			replace( /\(c\)/g	, '&copy;').
			replace( /\(r\)/g	, '&reg;').
			replace( /\(tm\)/g	, '&trade;').
			replace( /\-\-/g, '&mdash;');
	
		return text;
	};


	var _EncodeBackslashEscapes = function (text) {
		//
		//   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;
	};


	var _DoAutoLinks = function (text) {

		text = text.replace(/(?:")<((https?|ftp|dict):[^'">\s]+)>/gi, "<a href=\"$1\">$1</a>");

		// Email addresses: <address@domain.foo>
/*
		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;
	};


	var _EncodeEmailAddress = function (addr) {
		//
		//  Input: an email address, e.g. "foo@example.com"
		//
		//  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) {
			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 > 0.9 ? encode[2](ch) : r > 0.45 ? 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;
	};


	var _UnescapeSpecialChars = function (text) {
		//
		// Swap back in all the special characters we've hidden.
		//
		text = text.replace(/~E(\d+)E/g, function (wholeMatch, m1) {
			var charCodeToReplace = parseInt(m1,10);
			return String.fromCharCode(charCodeToReplace);
		});
		return text;
	};


	var _Outdent = function (text) {
		//
		// 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;
	};

	var _Detab = function (text) {
		// 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
	//

	var escapeCharacters = function (text, charsToEscape, afterBackslash) {
		// 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;
	};


	var escapeCharacters_callback = function (wholeMatch, m1) {
		var charCodeToEscape = m1.charCodeAt(0);
		return "~E" + charCodeToEscape + "E";
	};

}; // end of Attacklab.showdown.converter