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showdown.js

showdown.js -- A javascript port of Markdown. Copyright (c) 2007 John Fraser. Original Markdown Copyright (c) 2004-2005 John Gruber Redistributable under a BSD-style open source license. See license.txt for more information. The full source distribution is at: A A L T C A T K B
Wherever possible, Showdown is a straight, line-by-line port of the Perl version of Markdown. This is not a normal parser design; it's basically just a series of string substitutions. It's hard to read and maintain this way, but keeping Showdown close to the original design makes it easier to port new features. More importantly, Showdown behaves like markdown.pl in most edge cases. So web applications can do client-side preview in Javascript, and then build identical HTML on the server. This port needs the new RegExp functionality of ECMA 262, 3rd Edition (i.e. Javascript 1.5). Most modern web browsers should do fine. Even with the new regular expression features, We do a lot of work to emulate Perl's regex functionality. The tricky changes in this file mostly have the "attacklab:" label. Major or self-explanatory changes don't. Smart diff tools like Araxis Merge will be able to match up this file with markdown.pl in a useful way. A little tweaking helps: in a copy of markdown.pl, replace "#" with "//" and replace "$text" with "text". Be sure to ignore whitespace and line endings.
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
var 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 and 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 = 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;
}


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(){...});
	*/
	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;
}


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

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.:
tags for inner block must be indented.
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 `
` and stop at the first `
`.
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` to `\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
. 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

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 = _DoAnchors(text);

Make links out of things like `` Must come after _DoAnchors(), because you can use < and > delimiters in inline links like [this]().
	text = _DoAutoLinks(text);
	text = _EncodeAmpsAndAngles(text);
	text = _DoItalicsAndBold(text);

Do hard breaks:
	text = text.replace(/  +\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) {

	/*
		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;
	
	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;
}


var _DoImages = function(text) {
Turn Markdown image shortcuts into 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 id="' + headerId(m1) + '">' + _RunSpanGamut(m1) + "</h1>");});

	text = text.replace(/^(.+)[ \t]*\n-+[ \t]*\n+/gm,
		function(matchFound,m1){return hashBlock('<h2 id="' + headerId(m1) + '">' + _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 + ' id="' + headerId(m2) + '">' + _RunSpanGamut(m2) + "</h" + h_level + ">");
		});

	function headerId(m) {
		return m.replace(/[^\w]/g, '').toLowerCase();
	}
	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 `` 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;
}

_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 `
` 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 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:

Just type foo `bar` baz at the prompt.

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 `bar` ...

	/*
		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;
}


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;");

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) {

MARK: Added word boundaries to prevent underscores in class names from being italiczed.
must go first:
	text = text.replace(/\b(\*\*|__)(?=\S)([^\r]*?\S[*_]*)\1\b/g,
		"<strong>$2</strong>");

	text = text.replace(/\b(\*|_)(?=\S)([^\r]*?\S)\1\b/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
 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;
}


var _FormParagraphs = function(text) {
Params: $text - string to process with html

tags

Strip leading and trailing lines:
	text = text.replace(/^\n+/g,"");
	text = text.replace(/\n+$/g,"");

	var grafs = text.split(/\n{2,}/g);
	var grafsOut = new Array();

Wrap

tags.

	var end = grafs.length;
	for (var i=0; i<end; i++) {
		var str = 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 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;");
	
	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:

	/*
		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.: foo @example.com Based on a filter by Matthew Wickline, posted to the BBEdit-Talk mailing list:
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 > .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;
}


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);
			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 Showdown.converter

export
if (typeof exports != 'undefined') exports.Showdown = Showdown;