Markdown.Converter.js

"use strict";
var Markdown;

if (typeof exports === "object" && typeof require === "function") // we're in a CommonJS (e.g. Node.js) module
    Markdown = exports;
else
    Markdown = {};

// The following text is included for historical reasons, but should
// be taken with a pinch of salt; it's not all true anymore.

//
// 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.
//


//
// Usage:
//
//   var text = "Markdown *rocks*.";
//
//   var converter = new Markdown.Converter();
//   var html = converter.makeHtml(text);
//
//   alert(html);
//
// Note: move the sample code to the bottom of this
// file before uncommenting it.
//

(function () {

    function identity(x) { return x; }
    function returnFalse(x) { return false; }

    function HookCollection() { }

    HookCollection.prototype = {

        chain: function (hookname, func) {
            var original = this[hookname];
            if (!original)
                throw new Error("unknown hook " + hookname);

            if (original === identity)
                this[hookname] = func;
            else
                this[hookname] = function (text) {
                    var args = Array.prototype.slice.call(arguments, 0);
                    args[0] = original.apply(null, args);
                    return func.apply(null, args);
                };
        },
        set: function (hookname, func) {
            if (!this[hookname])
                throw new Error("unknown hook " + hookname);
            this[hookname] = func;
        },
        addNoop: function (hookname) {
            this[hookname] = identity;
        },
        addFalse: function (hookname) {
            this[hookname] = returnFalse;
        }
    };

    Markdown.HookCollection = HookCollection;

    // g_urls and g_titles allow arbitrary user-entered strings as keys. This
    // caused an exception (and hence stopped the rendering) when the user entered
    // e.g. [push] or [__proto__]. Adding a prefix to the actual key prevents this
    // (since no builtin property starts with "s_"). See
    // http://meta.stackexchange.com/questions/64655/strange-wmd-bug
    // (granted, switching from Array() to Object() alone would have left only __proto__
    // to be a problem)
    function SaveHash() { }
    SaveHash.prototype = {
        set: function (key, value) {
            this["s_" + key] = value;
        },
        get: function (key) {
            return this["s_" + key];
        }
    };

    Markdown.Converter = function (OPTIONS) {
        var pluginHooks = this.hooks = new HookCollection();
        
        // given a URL that was encountered by itself (without markup), should return the link text that's to be given to this link
        pluginHooks.addNoop("plainLinkText");
        
        // called with the orignal text as given to makeHtml. The result of this plugin hook is the actual markdown source that will be cooked
        pluginHooks.addNoop("preConversion");
        
        // called with the text once all normalizations have been completed (tabs to spaces, line endings, etc.), but before any conversions have
        pluginHooks.addNoop("postNormalization");
        
        // Called with the text before / after creating block elements like code blocks and lists. Note that this is called recursively
        // with inner content, e.g. it's called with the full text, and then only with the content of a blockquote. The inner
        // call will receive outdented text.
        pluginHooks.addNoop("preBlockGamut");
        pluginHooks.addNoop("postBlockGamut");
        
        // called with the text of a single block element before / after the span-level conversions (bold, code spans, etc.) have been made
        pluginHooks.addNoop("preSpanGamut");
        pluginHooks.addNoop("postSpanGamut");
        
        // called with the final cooked HTML code. The result of this plugin hook is the actual output of makeHtml
        pluginHooks.addNoop("postConversion");

        //
        // Private state of the converter instance:
        //

        // 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;
        
        OPTIONS = OPTIONS || {};
        var asciify = identity, deasciify = identity;
        if (OPTIONS.nonAsciiLetters) {

            /* In JavaScript regular expressions, \w only denotes [a-zA-Z0-9_].
             * That's why there's inconsistent handling e.g. with intra-word bolding
             * of Japanese words. That's why we do the following if OPTIONS.nonAsciiLetters
             * is true:
             *
             * Before doing bold and italics, we find every instance
             * of a unicode word character in the Markdown source that is not
             * matched by \w, and the letter "Q". We take the character's code point
             * and encode it in base 51, using the "digits"
             *
             *     A, B, ..., P, R, ..., Y, Z, a, b, ..., y, z
             *
             * delimiting it with "Q" on both sides. For example, the source
             *
             * > In Chinese, the smurfs are called 藍精靈, meaning "blue spirits".
             *
             * turns into
             *
             * > In Chinese, the smurfs are called QNIhQQMOIQQOuUQ, meaning "blue spirits".
             *
             * Since everything that is a letter in Unicode is now a letter (or
             * several letters) in ASCII, \w and \b should always do the right thing.
             *
             * After the bold/italic conversion, we decode again; since "Q" was encoded
             * alongside all non-ascii characters (as "QBfQ"), and the conversion
             * will not generate "Q", the only instances of that letter should be our
             * encoded characters. And since the conversion will not break words, the
             * "Q...Q" should all still be in one piece.
             *
             * We're using "Q" as the delimiter because it's probably one of the
             * rarest characters, and also because I can't think of any special behavior
             * that would ever be triggered by this letter (to use a silly example, if we
             * delimited with "H" on the left and "P" on the right, then "Ψ" would be
             * encoded as "HTTP", which may cause special behavior). The latter would not
             * actually be a huge issue for bold/italic, but may be if we later use it
             * in other places as well.
             * */            
            (function () {
                var lettersThatJavaScriptDoesNotKnowAndQ = /[Q\u00aa\u00b5\u00ba\u00c0-\u00d6\u00d8-\u00f6\u00f8-\u02c1\u02c6-\u02d1\u02e0-\u02e4\u02ec\u02ee\u0370-\u0374\u0376-\u0377\u037a-\u037d\u0386\u0388-\u038a\u038c\u038e-\u03a1\u03a3-\u03f5\u03f7-\u0481\u048a-\u0523\u0531-\u0556\u0559\u0561-\u0587\u05d0-\u05ea\u05f0-\u05f2\u0621-\u064a\u0660-\u0669\u066e-\u066f\u0671-\u06d3\u06d5\u06e5-\u06e6\u06ee-\u06fc\u06ff\u0710\u0712-\u072f\u074d-\u07a5\u07b1\u07c0-\u07ea\u07f4-\u07f5\u07fa\u0904-\u0939\u093d\u0950\u0958-\u0961\u0966-\u096f\u0971-\u0972\u097b-\u097f\u0985-\u098c\u098f-\u0990\u0993-\u09a8\u09aa-\u09b0\u09b2\u09b6-\u09b9\u09bd\u09ce\u09dc-\u09dd\u09df-\u09e1\u09e6-\u09f1\u0a05-\u0a0a\u0a0f-\u0a10\u0a13-\u0a28\u0a2a-\u0a30\u0a32-\u0a33\u0a35-\u0a36\u0a38-\u0a39\u0a59-\u0a5c\u0a5e\u0a66-\u0a6f\u0a72-\u0a74\u0a85-\u0a8d\u0a8f-\u0a91\u0a93-\u0aa8\u0aaa-\u0ab0\u0ab2-\u0ab3\u0ab5-\u0ab9\u0abd\u0ad0\u0ae0-\u0ae1\u0ae6-\u0aef\u0b05-\u0b0c\u0b0f-\u0b10\u0b13-\u0b28\u0b2a-\u0b30\u0b32-\u0b33\u0b35-\u0b39\u0b3d\u0b5c-\u0b5d\u0b5f-\u0b61\u0b66-\u0b6f\u0b71\u0b83\u0b85-\u0b8a\u0b8e-\u0b90\u0b92-\u0b95\u0b99-\u0b9a\u0b9c\u0b9e-\u0b9f\u0ba3-\u0ba4\u0ba8-\u0baa\u0bae-\u0bb9\u0bd0\u0be6-\u0bef\u0c05-\u0c0c\u0c0e-\u0c10\u0c12-\u0c28\u0c2a-\u0c33\u0c35-\u0c39\u0c3d\u0c58-\u0c59\u0c60-\u0c61\u0c66-\u0c6f\u0c85-\u0c8c\u0c8e-\u0c90\u0c92-\u0ca8\u0caa-\u0cb3\u0cb5-\u0cb9\u0cbd\u0cde\u0ce0-\u0ce1\u0ce6-\u0cef\u0d05-\u0d0c\u0d0e-\u0d10\u0d12-\u0d28\u0d2a-\u0d39\u0d3d\u0d60-\u0d61\u0d66-\u0d6f\u0d7a-\u0d7f\u0d85-\u0d96\u0d9a-\u0db1\u0db3-\u0dbb\u0dbd\u0dc0-\u0dc6\u0e01-\u0e30\u0e32-\u0e33\u0e40-\u0e46\u0e50-\u0e59\u0e81-\u0e82\u0e84\u0e87-\u0e88\u0e8a\u0e8d\u0e94-\u0e97\u0e99-\u0e9f\u0ea1-\u0ea3\u0ea5\u0ea7\u0eaa-\u0eab\u0ead-\u0eb0\u0eb2-\u0eb3\u0ebd\u0ec0-\u0ec4\u0ec6\u0ed0-\u0ed9\u0edc-\u0edd\u0f00\u0f20-\u0f29\u0f40-\u0f47\u0f49-\u0f6c\u0f88-\u0f8b\u1000-\u102a\u103f-\u1049\u1050-\u1055\u105a-\u105d\u1061\u1065-\u1066\u106e-\u1070\u1075-\u1081\u108e\u1090-\u1099\u10a0-\u10c5\u10d0-\u10fa\u10fc\u1100-\u1159\u115f-\u11a2\u11a8-\u11f9\u1200-\u1248\u124a-\u124d\u1250-\u1256\u1258\u125a-\u125d\u1260-\u1288\u128a-\u128d\u1290-\u12b0\u12b2-\u12b5\u12b8-\u12be\u12c0\u12c2-\u12c5\u12c8-\u12d6\u12d8-\u1310\u1312-\u1315\u1318-\u135a\u1380-\u138f\u13a0-\u13f4\u1401-\u166c\u166f-\u1676\u1681-\u169a\u16a0-\u16ea\u1700-\u170c\u170e-\u1711\u1720-\u1731\u1740-\u1751\u1760-\u176c\u176e-\u1770\u1780-\u17b3\u17d7\u17dc\u17e0-\u17e9\u1810-\u1819\u1820-\u1877\u1880-\u18a8\u18aa\u1900-\u191c\u1946-\u196d\u1970-\u1974\u1980-\u19a9\u19c1-\u19c7\u19d0-\u19d9\u1a00-\u1a16\u1b05-\u1b33\u1b45-\u1b4b\u1b50-\u1b59\u1b83-\u1ba0\u1bae-\u1bb9\u1c00-\u1c23\u1c40-\u1c49\u1c4d-\u1c7d\u1d00-\u1dbf\u1e00-\u1f15\u1f18-\u1f1d\u1f20-\u1f45\u1f48-\u1f4d\u1f50-\u1f57\u1f59\u1f5b\u1f5d\u1f5f-\u1f7d\u1f80-\u1fb4\u1fb6-\u1fbc\u1fbe\u1fc2-\u1fc4\u1fc6-\u1fcc\u1fd0-\u1fd3\u1fd6-\u1fdb\u1fe0-\u1fec\u1ff2-\u1ff4\u1ff6-\u1ffc\u203f-\u2040\u2054\u2071\u207f\u2090-\u2094\u2102\u2107\u210a-\u2113\u2115\u2119-\u211d\u2124\u2126\u2128\u212a-\u212d\u212f-\u2139\u213c-\u213f\u2145-\u2149\u214e\u2183-\u2184\u2c00-\u2c2e\u2c30-\u2c5e\u2c60-\u2c6f\u2c71-\u2c7d\u2c80-\u2ce4\u2d00-\u2d25\u2d30-\u2d65\u2d6f\u2d80-\u2d96\u2da0-\u2da6\u2da8-\u2dae\u2db0-\u2db6\u2db8-\u2dbe\u2dc0-\u2dc6\u2dc8-\u2dce\u2dd0-\u2dd6\u2dd8-\u2dde\u2e2f\u3005-\u3006\u3031-\u3035\u303b-\u303c\u3041-\u3096\u309d-\u309f\u30a1-\u30fa\u30fc-\u30ff\u3105-\u312d\u3131-\u318e\u31a0-\u31b7\u31f0-\u31ff\u3400-\u4db5\u4e00-\u9fc3\ua000-\ua48c\ua500-\ua60c\ua610-\ua62b\ua640-\ua65f\ua662-\ua66e\ua67f-\ua697\ua717-\ua71f\ua722-\ua788\ua78b-\ua78c\ua7fb-\ua801\ua803-\ua805\ua807-\ua80a\ua80c-\ua822\ua840-\ua873\ua882-\ua8b3\ua8d0-\ua8d9\ua900-\ua925\ua930-\ua946\uaa00-\uaa28\uaa40-\uaa42\uaa44-\uaa4b\uaa50-\uaa59\uac00-\ud7a3\uf900-\ufa2d\ufa30-\ufa6a\ufa70-\ufad9\ufb00-\ufb06\ufb13-\ufb17\ufb1d\ufb1f-\ufb28\ufb2a-\ufb36\ufb38-\ufb3c\ufb3e\ufb40-\ufb41\ufb43-\ufb44\ufb46-\ufbb1\ufbd3-\ufd3d\ufd50-\ufd8f\ufd92-\ufdc7\ufdf0-\ufdfb\ufe33-\ufe34\ufe4d-\ufe4f\ufe70-\ufe74\ufe76-\ufefc\uff10-\uff19\uff21-\uff3a\uff3f\uff41-\uff5a\uff66-\uffbe\uffc2-\uffc7\uffca-\uffcf\uffd2-\uffd7\uffda-\uffdc]/g;
                var cp_Q = "Q".charCodeAt(0);
                var cp_A = "A".charCodeAt(0);
                var cp_Z = "Z".charCodeAt(0);
                var dist_Za = "a".charCodeAt(0) - cp_Z - 1;
                
                asciify = function(text) {
                    return text.replace(lettersThatJavaScriptDoesNotKnowAndQ, function (m) {
                        var c = m.charCodeAt(0);
                        var s = "";
                        var v;
                        while (c > 0) {
                            v = (c % 51) + cp_A;
                            if (v >= cp_Q)
                                v++;
                            if (v > cp_Z)
                                v += dist_Za;
                            s = String.fromCharCode(v) + s;
                            c = c / 51 | 0;
                        }
                        return "Q" + s + "Q";
                    })
                };
                
                deasciify = function(text) {
                    return text.replace(/Q([A-PR-Za-z]{1,3})Q/g, function (m, s) {
                        var c = 0;
                        var v;
                        for (var i = 0; i < s.length; i++) {
                            v = s.charCodeAt(i);
                            if (v > cp_Z)
                                v -= dist_Za;
                            if (v > cp_Q)
                                v--;
                            v -= cp_A;
                            c = (c * 51) + v;
                        }
                        return String.fromCharCode(c);
                    })
                }                
            })();
        }
        
        var _DoItalicsAndBold = OPTIONS.asteriskIntraWordEmphasis ? _DoItalicsAndBold_AllowIntrawordWithAsterisk : _DoItalicsAndBoldStrict;

        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.
            //

            // This will only happen if makeHtml on the same converter instance is called from a plugin hook.
            // Don't do that.
            if (g_urls)
                throw new Error("Recursive call to converter.makeHtml");
        
            // Create the private state objects.
            g_urls = new SaveHash();
            g_titles = new SaveHash();
            g_html_blocks = [];
            g_list_level = 0;

            text = pluginHooks.preConversion(text);

            // 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, "");
            
            text = pluginHooks.postNormalization(text);

            // 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, "~");

            text = pluginHooks.postConversion(text);

            g_html_blocks = g_titles = g_urls = null;

            return text;
        };

        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"

            /*
            text = text.replace(/
                ^[ ]{0,3}\[([^\[\]]+)\]:  // id = $1  attacklab: g_tab_width - 1
                [ \t]*
                \n?                 // maybe *one* newline
                [ \t]*
                <?(\S+?)>?          // url = $2
                (?=\s|$)            // lookahead for whitespace instead of the lookbehind removed below
                [ \t]*
                \n?                 // maybe one newline
                [ \t]*
                (                   // (potential) title = $3
                    (\n*)           // any lines skipped = $4 attacklab: lookbehind removed
                    [ \t]+
                    ["(]
                    (.+?)           // title = $5
                    [")]
                    [ \t]*
                )?                  // title is optional
                (\n+)             // subsequent newlines = $6, capturing because they must be put back if the potential title isn't an actual title
            /gm, function(){...});
            */

            text = text.replace(/^[ ]{0,3}\[([^\[\]]+)\]:[ \t]*\n?[ \t]*<?(\S+?)>?(?=\s|$)[ \t]*\n?[ \t]*((\n*)["(](.+?)[")][ \t]*)?(\n+)/gm,
                function (wholeMatch, m1, m2, m3, m4, m5, m6) {
                    m1 = m1.toLowerCase();
                    g_urls.set(m1, _EncodeAmpsAndAngles(m2));  // Link IDs are case-insensitive
                    if (m4) {
                        // Oops, found blank lines, so it's not a title.
                        // Put back the parenthetical statement we stole.
                        return m3 + m6;
                    } else if (m5) {
                        g_titles.set(m1, m5.replace(/"/g, "&quot;"));
                    }

                    // Completely remove the definition from the text
                    return "";
                }
            );

            return text;
        }

        function _HashHTMLBlocks(text) {

            // 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.

            /*
            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, hashMatch);

            //
            // Now match more liberally, simply from `\n<tag>` to `</tag>\n`
            //

            /*
            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, hashMatch);

            // Special case just for <hr />. It was easier to make a special case than
            // to make the other regex more complicated.  

            /*
            text = text.replace(/
                \n                  // Starting after a blank line
                [ ]{0,3}
                (                   // save in $1
                    (<(hr)          // start tag = $2
                        \b          // word break
                        ([^<>])*?
                    \/?>)           // the matching end tag
                    [ \t]*
                    (?=\n{2,})      // followed by a blank line
                )
            /g,hashMatch);
            */
            text = text.replace(/\n[ ]{0,3}((<(hr)\b([^<>])*?\/?>)[ \t]*(?=\n{2,}))/g, hashMatch);

            // Special case for standalone HTML comments:

            /*
            text = text.replace(/
                \n\n                                            // Starting after a blank line
                [ ]{0,3}                                        // attacklab: g_tab_width - 1
                (                                               // save in $1
                    <!
                    (--(?:|(?:[^>-]|-[^>])(?:[^-]|-[^-])*)--)   // see http://www.w3.org/TR/html-markup/syntax.html#comments and http://meta.stackexchange.com/q/95256
                    >
                    [ \t]*
                    (?=\n{2,})                                  // followed by a blank line
                )
            /g,hashMatch);
            */
            text = text.replace(/\n\n[ ]{0,3}(<!(--(?:|(?:[^>-]|-[^>])(?:[^-]|-[^-])*)--)>[ \t]*(?=\n{2,}))/g, hashMatch);

            // 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,hashMatch);
            */
            text = text.replace(/(?:\n\n)([ ]{0,3}(?:<([?%])[^\r]*?\2>)[ \t]*(?=\n{2,}))/g, hashMatch);

            return text;
        }

        function hashBlock(text) {
            text = text.replace(/(^\n+|\n+$)/g, "");
            // Replace the element text with a marker ("~KxK" where x is its key)
            return "\n\n~K" + (g_html_blocks.push(text) - 1) + "K\n\n";
        }

        function hashMatch(wholeMatch, m1) {
            return hashBlock(m1);
        }
        
        var blockGamutHookCallback = function (t) { return _RunBlockGamut(t); }

        function _RunBlockGamut(text, doNotUnhash, doNotCreateParagraphs) {
            //
            // These are all the transformations that form block-level
            // tags like paragraphs, headers, and list items.
            //
            
            text = pluginHooks.preBlockGamut(text, blockGamutHookCallback);
            
            text = _DoHeaders(text);

            // Do Horizontal Rules:
            var replacement = "<hr />\n";
            text = text.replace(/^[ ]{0,2}([ ]?\*[ ]?){3,}[ \t]*$/gm, replacement);
            text = text.replace(/^[ ]{0,2}([ ]?-[ ]?){3,}[ \t]*$/gm, replacement);
            text = text.replace(/^[ ]{0,2}([ ]?_[ ]?){3,}[ \t]*$/gm, replacement);

            text = _DoLists(text);
            text = _DoCodeBlocks(text);
            text = _DoBlockQuotes(text);
            
            text = pluginHooks.postBlockGamut(text, blockGamutHookCallback);

            // 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, doNotUnhash, doNotCreateParagraphs);

            return text;
        }

        function _RunSpanGamut(text) {
            //
            // These are all the transformations that occur *within* block-level
            // tags like paragraphs, headers, and list items.
            //

            text = pluginHooks.preSpanGamut(text);
            
            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 = text.replace(/~P/g, "://"); // put in place to prevent autolinking; reset now
            
            text = _EncodeAmpsAndAngles(text);
            text = _DoItalicsAndBold(text);

            // Do hard breaks:
            text = text.replace(/  +\n/g, " <br>\n");
            
            text = pluginHooks.postSpanGamut(text);

            return text;
        }

        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.

            // SE: changed the comment part of the regex

            var regex = /(<[a-z\/!$]("[^"]*"|'[^']*'|[^'">])*>|<!(--(?:|(?:[^>-]|-[^>])(?:[^-]|-[^-])*)--)>)/gi;

            text = text.replace(regex, function (wholeMatch) {
                var tag = wholeMatch.replace(/(.)<\/?code>(?=.)/g, "$1`");
                tag = escapeCharacters(tag, wholeMatch.charAt(1) == "!" ? "\\`*_/" : "\\`*_"); // also escape slashes in comments to prevent autolinking there -- http://meta.stackexchange.com/questions/95987
                return tag;
            });

            return text;
        }

        function _DoAnchors(text) {
            
            if (text.indexOf("[") === -1)
                return 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, writeAnchorTag);
            */
            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
                        (?:
                            \([^)]*\)       // allow one level of (correctly nested) parens (think MSDN)
                            |
                            [^()\s]
                        )*?
                    )>?                
                    [ \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]*()<?((?:\([^)]*\)|[^()\s])*?)>?[ \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;
        }

        function writeAnchorTag(wholeMatch, m1, m2, m3, m4, m5, m6, m7) {
            if (m7 == undefined) m7 = "";
            var whole_match = m1;
            var link_text = m2.replace(/:\/\//g, "~P"); // to prevent auto-linking withing the link. will be converted back after the auto-linker runs
            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.get(link_id) != undefined) {
                    url = g_urls.get(link_id);
                    if (g_titles.get(link_id) != undefined) {
                        title = g_titles.get(link_id);
                    }
                }
                else {
                    if (whole_match.search(/\(\s*\)$/m) > -1) {
                        // Special case for explicit empty url
                        url = "";
                    } else {
                        return whole_match;
                    }
                }
            }
            url = attributeSafeUrl(url);

            var result = "<a href=\"" + url + "\"";

            if (title != "") {
                title = attributeEncode(title);
                title = escapeCharacters(title, "*_");
                result += " title=\"" + title + "\"";
            }

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

            return result;
        }

        function _DoImages(text) {
            
            if (text.indexOf("![") === -1)
                return 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;
        }
        
        function attributeEncode(text) {
            // unconditionally replace angle brackets here -- what ends up in an attribute (e.g. alt or title)
            // never makes sense to have verbatim HTML in it (and the sanitizer would totally break it)
            return text.replace(/>/g, "&gt;").replace(/</g, "&lt;").replace(/"/g, "&quot;").replace(/'/g, "&#39;");
        }

        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.get(link_id) != undefined) {
                    url = g_urls.get(link_id);
                    if (g_titles.get(link_id) != undefined) {
                        title = g_titles.get(link_id);
                    }
                }
                else {
                    return whole_match;
                }
            }
            
            alt_text = escapeCharacters(attributeEncode(alt_text), "*_[]()");
            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 = attributeEncode(title);
            title = escapeCharacters(title, "*_");
            result += " title=\"" + title + "\"";
            //}

            result += " />";

            return result;
        }

        function _DoHeaders(text) {

            // Setext-style headers:
            //  Header 1
            //  ========
            //  
            //  Header 2
            //  --------
            //
            text = text.replace(/^(.+)[ \t]*\n=+[ \t]*\n+/gm,
                function (wholeMatch, m1) { return "<h1>" + _RunSpanGamut(m1) + "</h1>\n\n"; }
            );

            text = text.replace(/^(.+)[ \t]*\n-+[ \t]*\n+/gm,
                function (matchFound, m1) { return "<h2>" + _RunSpanGamut(m1) + "</h2>\n\n"; }
            );

            // 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 "<h" + h_level + ">" + _RunSpanGamut(m2) + "</h" + h_level + ">\n\n";
                }
            );

            return text;
        }

        function _DoLists(text, isInsideParagraphlessListItem) {
            //
            // 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";
                    var first_number;
                    if (list_type === "ol")
                        first_number = parseInt(m2, 10)

                    var result = _ProcessListItems(list, list_type, isInsideParagraphlessListItem);

                    // Trim any trailing whitespace, to put the closing `</$list_type>`
                    // up on the preceding line, to get it past the current stupid
                    // HTML block parser. This is a hack to work around the terrible
                    // hack that is the HTML block parser.
                    result = result.replace(/\s+$/, "");
                    var opening = "<" + list_type;
                    if (first_number && first_number !== 1)
                        opening += " start=\"" + first_number + "\"";
                    result = opening + ">" + 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";

                    var first_number;
                    if (list_type === "ol")
                        first_number = parseInt(m3, 10)

                    var result = _ProcessListItems(list, list_type);
                    var opening = "<" + list_type;
                    if (first_number && first_number !== 1)
                        opening += " start=\"" + first_number + "\"";

                    result = runup + opening + ">\n" + result + "</" + list_type + ">\n";
                    return result;
                });
            }

            // attacklab: strip sentinel
            text = text.replace(/~0/, "");

            return text;
        }

        var _listItemMarkers = { ol: "\\d+[.]", ul: "[*+-]" };

        function _ProcessListItems(list_str, list_type, isInsideParagraphlessListItem) {
            //
            //  Process the contents of a single ordered or unordered list, splitting it
            //  into individual list items.
            //
            //  list_type is either "ul" or "ol".

            // 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";

            // In the original attacklab showdown, list_type was not given to this function, and anything
            // that matched /[*+-]|\d+[.]/ would just create the next <li>, causing this mismatch:
            //
            //  Markdown          rendered by WMD        rendered by MarkdownSharp
            //  ------------------------------------------------------------------
            //  1. first          1. first               1. first
            //  2. second         2. second              2. second
            //  - third           3. third                   * third
            //
            // We changed this to behave identical to MarkdownSharp. This is the constructed RegEx,
            // with {MARKER} being one of \d+[.] or [*+-], depending on list_type:
        
            /*
            list_str = list_str.replace(/
                (^[ \t]*)                       // leading whitespace = $1
                ({MARKER}) [ \t]+               // list marker = $2
                ([^\r]+?                        // list item text   = $3
                    (\n+)
                )
                (?=
                    (~0 | \2 ({MARKER}) [ \t]+)
                )
            /gm, function(){...});
            */

            var marker = _listItemMarkers[list_type];
            var re = new RegExp("(^[ \\t]*)(" + marker + ")[ \\t]+([^\\r]+?(\\n+))(?=(~0|\\1(" + marker + ")[ \\t]+))", "gm");
            var last_item_had_a_double_newline = false;
            list_str = list_str.replace(re,
                function (wholeMatch, m1, m2, m3) {
                    var item = m3;
                    var leading_space = m1;
                    var ends_with_double_newline = /\n\n$/.test(item);
                    var contains_double_newline = ends_with_double_newline || item.search(/\n{2,}/) > -1;
                    
                    var loose = contains_double_newline || last_item_had_a_double_newline;
                    item = _RunBlockGamut(_Outdent(item), /* doNotUnhash = */true, /* doNotCreateParagraphs = */ !loose);
                    
                    last_item_had_a_double_newline = ends_with_double_newline;
                    return "<li>" + item + "</li>\n";
                }
            );

            // attacklab: strip sentinel
            list_str = list_str.replace(/~0/g, "");

            g_list_level--;
            return list_str;
        }

        function _DoCodeBlocks(text) {
            //
            //  Process Markdown `<pre><code>` blocks.
            //  

            /*
            text = text.replace(/
                (?:\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|^\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 "\n\n" + codeblock + "\n\n" + nextChar;
                }
            );

            // attacklab: strip sentinel
            text = text.replace(/~0/, "");

            return text;
        }

        function _DoCodeSpans(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 or backtick
                (`+)            // $2 = Opening run of `
                (?!`)           // and no more backticks -- match the full run
                (               // $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);
                    c = c.replace(/:\/\//g, "~P"); // to prevent auto-linking. Not necessary in code *blocks*, but in code spans. Will be converted back after the auto-linker runs.
                    return m1 + "<code>" + c + "</code>";
                }
            );

            return text;
        }

        function _EncodeCode(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;
        }

        function _DoItalicsAndBoldStrict(text) {

            if (text.indexOf("*") === -1 && text.indexOf("_") === - 1)
                return text;
            
            text = asciify(text);
        
            // <strong> must go first:
            
            // (^|[\W_])           Start with a non-letter or beginning of string. Store in \1.
            // (?:(?!\1)|(?=^))    Either the next character is *not* the same as the previous,
            //                     or we started at the end of the string (in which case the previous
            //                     group had zero width, so we're still there). Because the next
            //                     character is the marker, this means that if there are e.g. multiple
            //                     underscores in a row, we can only match the left-most ones (which
            //                     prevents foo___bar__ from getting bolded)
            // (\*|_)              The marker character itself, asterisk or underscore. Store in \2.
            // \2                  The marker again, since bold needs two.
            // (?=\S)              The first bolded character cannot be a space.
            // ([^\r]*?\S)         The actual bolded string. At least one character, and it cannot *end*
            //                     with a space either. Note that like in many other places, [^\r] is
            //                     just a workaround for JS' lack of single-line regexes; it's equivalent
            //                     to a . in an /s regex, because the string cannot contain any \r (they
            //                     are removed in the normalizing step).
            // \2\2                The marker character, twice -- end of bold.
            // (?!\2)              Not followed by another marker character (ensuring that we match the
            //                     rightmost two in a longer row)...
            // (?=[\W_]|$)         ...but by any other non-word character or the end of string.
            text = text.replace(/(^|[\W_])(?:(?!\1)|(?=^))(\*|_)\2(?=\S)([^\r]*?\S)\2\2(?!\2)(?=[\W_]|$)/g,
            "$1<strong>$3</strong>");

            // This is almost identical to the <strong> regex, except 1) there's obviously just one marker
            // character, and 2) the italicized string cannot contain the marker character.
            text = text.replace(/(^|[\W_])(?:(?!\1)|(?=^))(\*|_)(?=\S)((?:(?!\2)[^\r])*?\S)\2(?!\2)(?=[\W_]|$)/g,
            "$1<em>$3</em>");

            return deasciify(text);
        }

        function _DoItalicsAndBold_AllowIntrawordWithAsterisk(text) {
            
            if (text.indexOf("*") === -1 && text.indexOf("_") === - 1)
                return text;
            
            text = asciify(text);
        
            // <strong> must go first:
            // (?=[^\r][*_]|[*_])               Optimization only, to find potentially relevant text portions faster. Minimally slower in Chrome, but much faster in IE.
            // (                                Store in \1. This is the last character before the delimiter
            //     ^                            Either we're at the start of the string (i.e. there is no last character)...
            //     |                            ... or we allow one of the following:
            //     (?=                          (lookahead; we're not capturing this, just listing legal possibilities)
            //         \W__                     If the delimiter is __, then this last character must be non-word non-underscore (extra-word emphasis only)
            //         |
            //         (?!\*)[\W_]\*\*          If the delimiter is **, then this last character can be non-word non-asterisk (extra-word emphasis)...
            //         |
            //         \w\*\*\w                 ...or it can be word/underscore, but only if the first bolded character is such a character as well (intra-word emphasis)
            //     )
            //     [^\r]                        actually capture the character (can't use `.` since it could be \n)
            // )
            // (\*\*|__)                        Store in \2: the actual delimiter
            // (?!\2)                           not followed by the delimiter again (at most one more asterisk/underscore is allowed)
            // (?=\S)                           the first bolded character can't be a space
            // (                                Store in \3: the bolded string
            //                                  
            //     (?:|                         Look at all bolded characters except for the last one. Either that's empty, meaning only a single character was bolded...
            //       [^\r]*?                    ... otherwise take arbitrary characters, minimally matching; that's all bolded characters except for the last *two*
            //       (?!\2)                       the last two characters cannot be the delimiter itself (because that would mean four underscores/asterisks in a row)
            //       [^\r]                        capture the next-to-last bolded character
            //     )
            //     (?=                          lookahead at the very last bolded char and what comes after
            //         \S_                      for underscore-bolding, it can be any non-space
            //         |
            //         \w                       for asterisk-bolding (otherwise the previous alternative would've matched, since \w implies \S), either the last char is word/underscore...
            //         |
            //         \S\*\*(?:[\W_]|$)        ... or it's any other non-space, but in that case the character *after* the delimiter may not be a word character
            //     )
            //     .                            actually capture the last character (can use `.` this time because the lookahead ensures \S in all cases)
            // )
            // (?=                              lookahead; list the legal possibilities for the closing delimiter and its following character
            //     __(?:\W|$)                   for underscore-bolding, the following character (if any) must be non-word non-underscore
            //     |
            //     \*\*(?:[^*]|$)               for asterisk-bolding, any non-asterisk is allowed (note we already ensured above that it's not a word character if the last bolded character wasn't one)
            // )
            // \2                               actually capture the closing delimiter (and make sure that it matches the opening one)
          
            text = text.replace(/(?=[^\r][*_]|[*_])(^|(?=\W__|(?!\*)[\W_]\*\*|\w\*\*\w)[^\r])(\*\*|__)(?!\2)(?=\S)((?:|[^\r]*?(?!\2)[^\r])(?=\S_|\w|\S\*\*(?:[\W_]|$)).)(?=__(?:\W|$)|\*\*(?:[^*]|$))\2/g,
            "$1<strong>$3</strong>");

            // now <em>:
            // (?=[^\r][*_]|[*_])               Optimization, see above.
            // (                                Store in \1. This is the last character before the delimiter
            //     ^                            Either we're at the start of the string (i.e. there is no last character)...
            //     |                            ... or we allow one of the following:
            //     (?=                          (lookahead; we're not capturing this, just listing legal possibilities)
            //         \W_                      If the delimiter is _, then this last character must be non-word non-underscore (extra-word emphasis only)
            //         |
            //         (?!\*)                   otherwise, we list two possiblities for * as the delimiter; in either case, the last characters cannot be an asterisk itself
            //         (?:
            //             [\W_]\*              this last character can be non-word (extra-word emphasis)...
            //             |
            //             \D\*(?=\w)\D         ...or it can be word (otherwise the first alternative would've matched), but only if
            //                                      a) the first italicized character is such a character as well (intra-word emphasis), and
            //                                      b) neither character on either side of the asterisk is a digit            
            //         )
            //     )
            //     [^\r]                        actually capture the character (can't use `.` since it could be \n)
            // )
            // (\*|_)                           Store in \2: the actual delimiter
            // (?!\2\2\2)                       not followed by more than two more instances of the delimiter
            // (?=\S)                           the first italicized character can't be a space
            // (                                Store in \3: the italicized string
            //     (?:(?!\2)[^\r])*?            arbitrary characters except for the delimiter itself, minimally matching
            //     (?=                          lookahead at the very last italicized char and what comes after
            //         [^\s_]_                  for underscore-italicizing, it can be any non-space non-underscore
            //         |
            //         (?=\w)\D\*\D             for asterisk-italicizing, either the last char is word/underscore *and* neither character on either side of the asterisk is a digit...
            //         |
            //         [^\s*]\*(?:[\W_]|$)      ... or that last char is any other non-space non-asterisk, but then the character after the delimiter (if any) must be non-word
            //     )
            //     .                            actually capture the last character (can use `.` this time because the lookahead ensures \S in all cases)
            // )
            // (?=                              lookahead; list the legal possibilities for the closing delimiter and its following character
            //     _(?:\W|$)                    for underscore-italicizing, the following character (if any) must be non-word non-underscore
            //     |
            //     \*(?:[^*]|$)                 for asterisk-italicizing, any non-asterisk is allowed; all other restrictions have already been ensured in the previous lookahead
            // )
            // \2                               actually capture the closing delimiter (and make sure that it matches the opening one)

            text = text.replace(/(?=[^\r][*_]|[*_])(^|(?=\W_|(?!\*)(?:[\W_]\*|\D\*(?=\w)\D))[^\r])(\*|_)(?!\2\2\2)(?=\S)((?:(?!\2)[^\r])*?(?=[^\s_]_|(?=\w)\D\*\D|[^\s*]\*(?:[\W_]|$)).)(?=_(?:\W|$)|\*(?:[^*]|$))\2/g,
            "$1<em>$3</em>");
            
            return deasciify(text);
        }        

        
        function _DoBlockQuotes(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(/^  /mg, "~0");
                            pre = pre.replace(/~0/g, "");
                            return pre;
                        });

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

        function _FormParagraphs(text, doNotUnhash, doNotCreateParagraphs) {
            //
            //  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 = text.split(/\n{2,}/g);
            var grafsOut = [];
            
            var markerRe = /~K(\d+)K/;

            //
            // Wrap <p> 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 (markerRe.test(str)) {
                    grafsOut.push(str);
                }
                else if (/\S/.test(str)) {
                    str = _RunSpanGamut(str);
                    str = str.replace(/^([ \t]*)/g, doNotCreateParagraphs ? "" : "<p>");
                    if (!doNotCreateParagraphs)
                        str += "</p>"
                    grafsOut.push(str);
                }

            }
            //
            // Unhashify HTML blocks
            //
            if (!doNotUnhash) {
                end = grafsOut.length;
                for (var i = 0; i < end; i++) {
                    var foundAny = true;
                    while (foundAny) { // we may need several runs, since the data may be nested
                        foundAny = false;
                        grafsOut[i] = grafsOut[i].replace(/~K(\d+)K/g, function (wholeMatch, id) {
                            foundAny = true;
                            return g_html_blocks[id];
                        });
                    }
                }
            }
            return grafsOut.join("\n\n");
        }

        function _EncodeAmpsAndAngles(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\/?!]|~D)/gi, "&lt;");

            return text;
        }

        function _EncodeBackslashEscapes(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 charInsideUrl = "[-A-Z0-9+&@#/%?=~_|[\\]()!:,.;]",
            charEndingUrl = "[-A-Z0-9+&@#/%=~_|[\\])]",
            autoLinkRegex = new RegExp("(=\"|<)?\\b(https?|ftp)(://" + charInsideUrl + "*" + charEndingUrl + ")(?=$|\\W)", "gi"),
            endCharRegex = new RegExp(charEndingUrl, "i");

        function handleTrailingParens(wholeMatch, lookbehind, protocol, link) {
            if (lookbehind)
                return wholeMatch;
            if (link.charAt(link.length - 1) !== ")")
                return "<" + protocol + link + ">";
            var parens = link.match(/[()]/g);
            var level = 0;
            for (var i = 0; i < parens.length; i++) {
                if (parens[i] === "(") {
                    if (level <= 0)
                        level = 1;
                    else
                        level++;
                }
                else {
                    level--;
                }
            }
            var tail = "";
            if (level < 0) {
                var re = new RegExp("\\){1," + (-level) + "}$");
                link = link.replace(re, function (trailingParens) {
                    tail = trailingParens;
                    return "";
                });
            }
            if (tail) {
                var lastChar = link.charAt(link.length - 1);
                if (!endCharRegex.test(lastChar)) {
                    tail = lastChar + tail;
                    link = link.substr(0, link.length - 1);
                }
            }
            return "<" + protocol + link + ">" + tail;
        }
        
        function _DoAutoLinks(text) {

            // note that at this point, all other URL in the text are already hyperlinked as <a href=""></a>
            // *except* for the <http://www.foo.com> case

            // automatically add < and > around unadorned raw hyperlinks
            // must be preceded by a non-word character (and not by =" or <) and followed by non-word/EOF character
            // simulating the lookbehind in a consuming way is okay here, since a URL can neither and with a " nor
            // with a <, so there is no risk of overlapping matches.
            text = text.replace(autoLinkRegex, handleTrailingParens);

            //  autolink anything like <http://example.com>
            

            var replacer = function (wholematch, m1) {
                var url = attributeSafeUrl(m1);
                
                return "<a href=\"" + url + "\">" + pluginHooks.plainLinkText(m1) + "</a>";
            };
            text = text.replace(/<((https?|ftp):[^'">\s]+)>/gi, replacer);

            // Email addresses: <address@domain.foo>
            /*
            text = text.replace(/
                <
                (?:mailto:)?
                (
                    [-.\w]+
                    \@
                    [-a-z0-9]+(\.[-a-z0-9]+)*\.[a-z]+
                )
                >
            /gi, _DoAutoLinks_callback());
            */

            /* disabling email autolinking, since we don't do that on the server, either
            text = text.replace(/<(?:mailto:)?([-.\w]+\@[-a-z0-9]+(\.[-a-z0-9]+)*\.[a-z]+)>/gi,
                function(wholeMatch,m1) {
                    return _EncodeEmailAddress( _UnescapeSpecialChars(m1) );
                }
            );
            */
            return text;
        }

        function _UnescapeSpecialChars(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;
        }

        function _Outdent(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;
        }

        function _Detab(text) {
            if (!/\t/.test(text))
                return text;

            var spaces = ["    ", "   ", "  ", " "],
            skew = 0,
            v;

            return text.replace(/[\n\t]/g, function (match, offset) {
                if (match === "\n") {
                    skew = offset + 1;
                    return match;
                }
                v = (offset - skew) % 4;
                skew = offset + 1;
                return spaces[v];
            });
        }

        //
        //  attacklab: Utility functions
        //

        function attributeSafeUrl(url) {
            url = attributeEncode(url);
            url = escapeCharacters(url, "*_:()[]")
            return url;
        }

        function escapeCharacters(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;
        }


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

    }; // end of the Markdown.Converter constructor

})();