text: //
  // showdown.js -- A javascript port of Markdown.
  //
  // Copyright (c) 2007 John Fraser.
  //
  // Original Markdown Copyright (c) 2004-2005 John Gruber
  //   <http://daringfireball.net/projects/markdown/>
  //
  // Redistributable under a BSD-style open source license.
  // See license.txt for more information.
  //
  // The full source distribution is at:
  //
  //        A A L
  //        T C A
  //        T K B
  //
  //   <http://www.attacklab.net/>
  //
  //
  // 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 "$text" with "text".  Be sure to ignore whitespace
  // and line endings.
  //
  //
  // Showdown usage:
  //
  //   var text = "Markdown *rocks*.";
  //
  //   var converter = new Showdown.converter();
  //   var html = converter.makeHtml(text);
  //
  //   alert(html);
  //
  // Note: move the sample code to the bottom of this
  // file before uncommenting it.
  //
  //
  // Showdown namespace
  //
  var Showdown = { extensions: {} };
  //
  // forEach
  //
  var forEach = Showdown.forEach = function (obj, callback) {
      if (typeof obj.forEach === 'function') {
        obj.forEach(callback);
      } else {
        var i, len = obj.length;
        for (i = 0; i < len; i++) {
          callback(obj[i], i, obj);
        }
      }
    };
  //
  // Standard extension naming
  //
  var stdExtName = function (s) {
    return s.replace(/[_-]||\s/g, '').toLowerCase();
  };
  //
  // converter
  //
  // Wraps all "globals" so that the only thing
  // exposed is makeHtml().
  //
  Showdown.converter = function (converter_options) {
    //
    // Globals:
    //
    // Global hashes, used by various utility routines
    var g_urls;
    var g_titles;
    var g_html_blocks;
    // Used to track when we're inside an ordered or unordered list
    // (see _ProcessListItems() for details):
    var g_list_level = 0;
    // Global extensions
    var g_lang_extensions = [];
    var g_output_modifiers = [];
    //
    // Automatic Extension Loading (node only):
    //
    if (typeof module !== 'undefind' && typeof exports !== 'undefined' && typeof require !== 'undefind') {
      var fs = require('fs');
      if (fs) {
        // Search extensions folder
        var extensions = fs.readdirSync((__dirname || '.') + '/extensions').filter(function (file) {
            return ~file.indexOf('.js');
          }).map(function (file) {
            return file.replace(/\.js$/, '');
          });
        // Load extensions into Showdown namespace
        Showdown.forEach(extensions, function (ext) {
          var name = stdExtName(ext);
          Showdown.extensions[name] = require('./extensions/' + ext);
        });
      }
    }
    this.makeHtml = function (text) {
      //
      // Main function. The order in which other subs are called here is
      // essential. Link and image substitutions need to happen before
      // _EscapeSpecialCharsWithinTagAttributes(), so that any *'s or _'s in the <a>
      // and <img> tags get encoded.
      //
      // Clear the global hashes. If we don't clear these, you get conflicts
      // from other articles when generating a page which contains more than
      // one article (e.g. an index page that shows the N most recent
      // articles):
      g_urls = {};
      g_titles = {};
      g_html_blocks = [];
      // attacklab: Replace ~ with ~T
      // This lets us use tilde as an escape char to avoid md5 hashes
      // The choice of character is arbitray; anything that isn't
      // magic in Markdown will work.
      text = text.replace(/~/g, '~T');
      // attacklab: Replace $ with ~D
      // RegExp interprets $ as a special character
      // when it's in a replacement string
      text = text.replace(/\$/g, '~D');
      // Standardize line endings
      text = text.replace(/\r\n/g, '\n');
      // DOS to Unix
      text = text.replace(/\r/g, '\n');
      // Mac to Unix
      // Make sure text begins and ends with a couple of newlines:
      text = '\n\n' + text + '\n\n';
      // Convert all tabs to spaces.
      text = _Detab(text);
      // Strip any lines consisting only of spaces and tabs.
      // This makes subsequent regexen easier to write, because we can
      // match consecutive blank lines with /\n+/ instead of something
      // contorted like /[ \t]*\n+/ .
      text = text.replace(/^[ \t]+$/gm, '');
      // Run language extensions
      Showdown.forEach(g_lang_extensions, function (x) {
        text = _ExecuteExtension(x, text);
      });
      // Handle github codeblocks prior to running HashHTML so that
      // HTML contained within the codeblock gets escaped propertly
      text = _DoGithubCodeBlocks(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, '~');
      // Run output modifiers
      Showdown.forEach(g_output_modifiers, function (x) {
        text = _ExecuteExtension(x, text);
      });
      return text;
    };
    //
    // Options:
    //
    // Parse extensions options into separate arrays
    if (converter_options && converter_options.extensions) {
      var self = this;
      // Iterate over each plugin
      Showdown.forEach(converter_options.extensions, function (plugin) {
        // Assume it's a bundled plugin if a string is given
        if (typeof plugin === 'string') {
          plugin = Showdown.extensions[stdExtName(plugin)];
        }
        if (typeof plugin === 'function') {
          // Iterate over each extension within that plugin
          Showdown.forEach(plugin(self), function (ext) {
            // Sort extensions by type
            if (ext.type) {
              if (ext.type === 'language' || ext.type === 'lang') {
                g_lang_extensions.push(ext);
              } else if (ext.type === 'output' || ext.type === 'html') {
                g_output_modifiers.push(ext);
              }
            } else {
              // Assume language extension
              g_output_modifiers.push(ext);
            }
          });
        } else {
          throw 'Extension \'' + plugin + '\' could not be loaded.  It was either not found or is not a valid extension.';
        }
      });
    }
    var _ExecuteExtension = function (ext, text) {
      if (ext.regex) {
        var re = new RegExp(ext.regex, 'g');
        return text.replace(re, ext.replace);
      } else if (ext.filter) {
        return ext.filter(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(){...});
    */
      // attacklab: sentinel workarounds for lack of \A and \Z, safari\khtml bug
      text += '~0';
      text = text.replace(/^[ ]{0,3}\[(.+)\]:[ \t]*\n?[ \t]*<?(\S+?)>?[ \t]*\n?[ \t]*(?:(\n*)["(](.+?)[")][ \t]*)?(?:\n+|(?=~0))/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 '';
      });
      // attacklab: strip sentinel
      text = text.replace(/~0/, '');
      return text;
    };
    var _HashHTMLBlocks = function (text) {
      // attacklab: Double up blank lines to reduce lookaround
      text = text.replace(/\n/g, '\n\n');
      // Hashify HTML blocks:
      // We only want to do this for block-level HTML tags, such as headers,
      // lists, and tables. That's because we still want to wrap <p>s around
      // "paragraphs" that are wrapped in non-block-level tags, such as anchors,
      // phrase emphasis, and spans. The list of tags we're looking for is
      // hard-coded:
      var block_tags_a = 'p|div|h[1-6]|blockquote|pre|table|dl|ol|ul|script|noscript|form|fieldset|iframe|math|ins|del|style|section|header|footer|nav|article|aside';
      var block_tags_b = 'p|div|h[1-6]|blockquote|pre|table|dl|ol|ul|script|noscript|form|fieldset|iframe|math|style|section|header|footer|nav|article|aside';
      // First, look for nested blocks, e.g.:
      //   <div>
      //     <div>
      //     tags for inner block must be indented.
      //     </div>
      //   </div>
      //
      // The outermost tags must start at the left margin for this to match, and
      // the inner nested divs must be indented.
      // We need to do this before the next, more liberal match, because the next
      // match will start at the first `<div>` and stop at the first `</div>`.
      // attacklab: This regex can be expensive when it fails.
      /*
      var text = text.replace(/
      (           // save in $1
        ^         // start of line  (with /m)
        <($block_tags_a)  // start tag = $2
        \b          // word break
                  // attacklab: hack around khtml/pcre bug...
        [^\r]*?\n     // any number of lines, minimally matching
        </\2>       // the matching end tag
        [ \t]*        // trailing spaces/tabs
        (?=\n+)       // followed by a newline
      )           // attacklab: there are sentinel newlines at end of document
      /gm,function(){...}};
    */
      text = text.replace(/^(<(p|div|h[1-6]|blockquote|pre|table|dl|ol|ul|script|noscript|form|fieldset|iframe|math|ins|del)\b[^\r]*?\n<\/\2>[ \t]*(?=\n+))/gm, hashElement);
      //
      // Now match more liberally, simply from `\n<tag>` to `</tag>\n`
      //
      /*
      var text = text.replace(/
      (           // save in $1
        ^         // start of line  (with /m)
        <($block_tags_b)  // start tag = $2
        \b          // word break
                  // attacklab: hack around khtml/pcre bug...
        [^\r]*?       // any number of lines, minimally matching
        </\2>       // the matching end tag
        [ \t]*        // trailing spaces/tabs
        (?=\n+)       // followed by a newline
      )           // attacklab: there are sentinel newlines at end of document
      /gm,function(){...}};
    */
      text = text.replace(/^(<(p|div|h[1-6]|blockquote|pre|table|dl|ol|ul|script|noscript|form|fieldset|iframe|math|style|section|header|footer|nav|article|aside)\b[^\r]*?<\/\2>[ \t]*(?=\n+)\n)/gm, hashElement);
      // Special case just for <hr />. It was easier to make a special case than
      // to make the other regex more complicated.
      /*
      text = text.replace(/
      (           // save in $1
        \n\n        // Starting after a blank line
        [ ]{0,3}
        (<(hr)        // start tag = $2
        \b          // word break
        ([^<>])*?     //
        \/?>)       // the matching end tag
        [ \t]*
        (?=\n{2,})      // followed by a blank line
      )
      /g,hashElement);
    */
      text = text.replace(/(\n[ ]{0,3}(<(hr)\b([^<>])*?\/?>)[ \t]*(?=\n{2,}))/g, hashElement);
      // Special case for standalone HTML comments:
      /*
      text = text.replace(/
      (           // save in $1
        \n\n        // Starting after a blank line
        [ ]{0,3}      // attacklab: g_tab_width - 1
        <!
        (--[^\r]*?--\s*)+
        >
        [ \t]*
        (?=\n{2,})      // followed by a blank line
      )
      /g,hashElement);
    */
      text = text.replace(/(\n\n[ ]{0,3}<!(--[^\r]*?--\s*)+>[ \t]*(?=\n{2,}))/g, hashElement);
      // PHP and ASP-style processor instructions (<?...?> and <%...%>)
      /*
      text = text.replace(/
      (?:
        \n\n        // Starting after a blank line
      )
      (           // save in $1
        [ ]{0,3}      // attacklab: g_tab_width - 1
        (?:
          <([?%])     // $2
          [^\r]*?
          \2>
        )
        [ \t]*
        (?=\n{2,})      // followed by a blank line
      )
      /g,hashElement);
    */
      text = text.replace(/(?:\n\n)([ ]{0,3}(?:<([?%])[^\r]*?\2>)[ \t]*(?=\n{2,}))/g, hashElement);
      // attacklab: Undo double lines (see comment at top of this function)
      text = text.replace(/\n\n/g, '\n');
      return text;
    };
    var hashElement = function (wholeMatch, m1) {
      var blockText = m1;
      // Undo double lines
      blockText = blockText.replace(/\n\n/g, '\n');
      blockText = blockText.replace(/^\n/, '');
      // strip trailing blank lines
      blockText = blockText.replace(/\n+$/g, '');
      // Replace the element text with a marker ("~KxK" where x is its key)
      blockText = '\n\n~K' + (g_html_blocks.push(blockText) - 1) + 'K\n\n';
      return blockText;
    };
    var _RunBlockGamut = function (text) {
      //
      // These are all the transformations that form block-level
      // tags like paragraphs, headers, and list items.
      //
      text = _DoHeaders(text);
      // Do Horizontal Rules:
      var key = hashBlock('<hr />');
      text = text.replace(/^[ ]{0,2}([ ]?\*[ ]?){3,}[ \t]*$/gm, key);
      text = text.replace(/^[ ]{0,2}([ ]?\-[ ]?){3,}[ \t]*$/gm, key);
      text = text.replace(/^[ ]{0,2}([ ]?\_[ ]?){3,}[ \t]*$/gm, key);
      text = _DoLists(text);
      text = _DoCodeBlocks(text);
      text = _DoBlockQuotes(text);
      // We already ran _HashHTMLBlocks() before, in Markdown(), but that
      // was to escape raw HTML in the original Markdown source. This time,
      // we're escaping the markup we've just created, so that we don't wrap
      // <p> tags around block-level tags.
      text = _HashHTMLBlocks(text);
      text = _FormParagraphs(text);
      return text;
    };
    var _RunSpanGamut = function (text) {
      //
      // These are all the transformations that occur *within* block-level
      // tags like paragraphs, headers, and list items.
      //
      text = _DoCodeSpans(text);
      text = _EscapeSpecialCharsWithinTagAttributes(text);
      text = _EncodeBackslashEscapes(text);
      // Process anchor and image tags. Images must come first,
      // because ![foo][f] looks like an anchor.
      text = _DoImages(text);
      text = _DoAnchors(text);
      // Make links out of things like `<http://example.com/>`
      // Must come after _DoAnchors(), because you can use < and >
      // delimiters in inline links like [this](<url>).
      text = _DoAutoLinks(text);
      text = _EncodeAmpsAndAngles(text);
      text = _DoItalicsAndBold(text);
      // Do hard breaks:
      text = text.replace(/  +\n/g, ' <br />\n');
      return text;
    };
    var _EscapeSpecialCharsWithinTagAttributes = function (text) {
      //
      // Within tags -- meaning between < and > -- encode [\ ` * _] so they
      // don't conflict with their use in Markdown for code, italics and strong.
      //
      // Build a regex to find HTML tags and comments.  See Friedl's
      // "Mastering Regular Expressions", 2nd Ed., pp. 200-201.
      var regex = /(<[a-z\/!$]("[^"]*"|'[^']*'|[^'">])*>|<!(--.*?--\s*)+>)/gi;
      text = text.replace(regex, function (wholeMatch) {
        var tag = wholeMatch.replace(/(.)<\/?code>(?=.)/g, '$1`');
        tag = escapeCharacters(tag, '\\`*_');
        return tag;
      });
      return text;
    };
    var _DoAnchors = function (text) {
      //
      // Turn Markdown link shortcuts into XHTML <a> tags.
      //
      //
      // First, handle reference-style links: [link text] [id]
      //
      /*
      text = text.replace(/
      (             // wrap whole match in $1
        \[
        (
          (?:
            \[[^\]]*\]    // allow brackets nested one level
            |
            [^\[]     // or anything else
          )*
        )
        \]
  
        [ ]?          // one optional space
        (?:\n[ ]*)?       // one optional newline followed by spaces
  
        \[
        (.*?)         // id = $3
        \]
      )()()()()         // pad remaining backreferences
      /g,_DoAnchors_callback);
    */
      text = text.replace(/(\[((?:\[[^\]]*\]|[^\[\]])*)\][ ]?(?:\n[ ]*)?\[(.*?)\])()()()()/g, writeAnchorTag);
      //
      // Next, inline-style links: [link text](url "optional title")
      //
      /*
      text = text.replace(/
        (           // wrap whole match in $1
          \[
          (
            (?:
              \[[^\]]*\]  // allow brackets nested one level
            |
            [^\[\]]     // or anything else
          )
        )
        \]
        \(            // literal paren
        [ \t]*
        ()            // no id, so leave $3 empty
        <?(.*?)>?       // href = $4
        [ \t]*
        (           // $5
          (['"])        // quote char = $6
          (.*?)       // Title = $7
          \6          // matching quote
          [ \t]*        // ignore any spaces/tabs between closing quote and )
        )?            // title is optional
        \)
      )
      /g,writeAnchorTag);
    */
      text = text.replace(/(\[((?:\[[^\]]*\]|[^\[\]])*)\]\([ \t]*()<?(.*?(?:\(.*?\).*?)?)>?[ \t]*((['"])(.*?)\6[ \t]*)?\))/g, writeAnchorTag);
      //
      // Last, handle reference-style shortcuts: [link text]
      // These must come last in case you've also got [link test][1]
      // or [link test](/foo)
      //
      /*
      text = text.replace(/
      (             // wrap whole match in $1
        \[
        ([^\[\]]+)        // link text = $2; can't contain '[' or ']'
        \]
      )()()()()()         // pad rest of backreferences
      /g, writeAnchorTag);
    */
      text = text.replace(/(\[([^\[\]]+)\])()()()()()/g, writeAnchorTag);
      return text;
    };
    var writeAnchorTag = function (wholeMatch, m1, m2, m3, m4, m5, m6, m7) {
      if (m7 == undefined)
        m7 = '';
      var whole_match = m1;
      var link_text = m2;
      var link_id = m3.toLowerCase();
      var url = m4;
      var title = m7;
      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 <img> tags.
      //
      //
      // First, handle reference-style labeled images: ![alt text][id]
      //
      /*
      text = text.replace(/
      (           // wrap whole match in $1
        !\[
        (.*?)       // alt text = $2
        \]
  
        [ ]?        // one optional space
        (?:\n[ ]*)?     // one optional newline followed by spaces
  
        \[
        (.*?)       // id = $3
        \]
      )()()()()       // pad rest of backreferences
      /g,writeImageTag);
    */
      text = text.replace(/(!\[(.*?)\][ ]?(?:\n[ ]*)?\[(.*?)\])()()()()/g, writeImageTag);
      //
      // Next, handle inline images:  ![alt text](url "optional title")
      // Don't forget: encode * and _
      /*
      text = text.replace(/
      (           // wrap whole match in $1
        !\[
        (.*?)       // alt text = $2
        \]
        \s?         // One optional whitespace character
        \(          // literal paren
        [ \t]*
        ()          // no id, so leave $3 empty
        <?(\S+?)>?      // src url = $4
        [ \t]*
        (         // $5
          (['"])      // quote char = $6
          (.*?)     // title = $7
          \6        // matching quote
          [ \t]*
        )?          // title is optional
      \)
      )
      /g,writeImageTag);
    */
      text = text.replace(/(!\[(.*?)\]\s?\([ \t]*()<?(\S+?)>?[ \t]*((['"])(.*?)\6[ \t]*)?\))/g, writeImageTag);
      return text;
    };
    var writeImageTag = function (wholeMatch, m1, m2, m3, m4, m5, m6, m7) {
      var whole_match = m1;
      var alt_text = m2;
      var link_id = m3.toLowerCase();
      var url = m4;
      var title = m7;
      if (!title)
        title = '';
      if (url == '') {
        if (link_id == '') {
          // lower-case and turn embedded newlines into spaces
          link_id = alt_text.toLowerCase().replace(/ ?\n/g, ' ');
        }
        url = '#' + link_id;
        if (g_urls[link_id] != undefined) {
          url = g_urls[link_id];
          if (g_titles[link_id] != undefined) {
            title = g_titles[link_id];
          }
        } else {
          return whole_match;
        }
      }
      alt_text = alt_text.replace(/"/g, '&quot;');
      url = escapeCharacters(url, '*_');
      var result = '<img src="' + url + '" alt="' + alt_text + '"';
      // attacklab: Markdown.pl adds empty title attributes to images.
      // Replicate this bug.
      //if (title != "") {
      title = title.replace(/"/g, '&quot;');
      title = escapeCharacters(title, '*_');
      result += ' title="' + title + '"';
      //}
      result += ' />';
      return result;
    };
    var _DoHeaders = function (text) {
      // Setext-style headers:
      //  Header 1
      //  ========
      //
      //  Header 2
      //  --------
      //
      text = text.replace(/^(.+)[ \t]*\n=+[ \t]*\n+/gm, function (wholeMatch, m1) {
        return hashBlock('<h1 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 `</$list_type>`
          // up on the preceding line, to get it past the current stupid
          // HTML block parser. This is a hack to work around the terrible
          // hack that is the HTML block parser.
          result = result.replace(/\s+$/, '');
          result = '<' + list_type + '>' + result + '</' + list_type + '>\n';
          return result;
        });
      } else {
        whole_list = /(\n\n|^\n?)(([ ]{0,3}([*+-]|\d+[.])[ \t]+)[^\r]+?(~0|\n{2,}(?=\S)(?![ \t]*(?:[*+-]|\d+[.])[ \t]+)))/g;
        text = text.replace(whole_list, function (wholeMatch, m1, m2, m3) {
          var runup = m1;
          var list = m2;
          var list_type = m3.search(/[*+-]/g) > -1 ? 'ul' : 'ol';
          // Turn double returns into triple returns, so that we can make a
          // paragraph for the last item in a list, if necessary:
          var list = list.replace(/\n{2,}/g, '\n\n\n');
          ;
          var result = _ProcessListItems(list);
          result = runup + '<' + list_type + '>\n' + result + '</' + list_type + '>\n';
          return result;
        });
      }
      // attacklab: strip sentinel
      text = text.replace(/~0/, '');
      return text;
    };
    _ProcessListItems = function (list_str) {
      //
      //  Process the contents of a single ordered or unordered list, splitting it
      //  into individual list items.
      //
      // The $g_list_level global keeps track of when we're inside a list.
      // Each time we enter a list, we increment it; when we leave a list,
      // we decrement. If it's zero, we're not in a list anymore.
      //
      // We do this because when we're not inside a list, we want to treat
      // something like this:
      //
      //    I recommend upgrading to version
      //    8. Oops, now this line is treated
      //    as a sub-list.
      //
      // As a single paragraph, despite the fact that the second line starts
      // with a digit-period-space sequence.
      //
      // Whereas when we're inside a list (or sub-list), that line will be
      // treated as the start of a sub-list. What a kludge, huh? This is
      // an aspect of Markdown's syntax that's hard to parse perfectly
      // without resorting to mind-reading. Perhaps the solution is to
      // change the syntax rules such that sub-lists must start with a
      // starting cardinal number; e.g. "1." or "a.".
      g_list_level++;
      // trim trailing blank lines:
      list_str = list_str.replace(/\n{2,}$/, '\n');
      // attacklab: add sentinel to emulate \z
      list_str += '~0';
      /*
      list_str = list_str.replace(/
        (\n)?             // leading line = $1
        (^[ \t]*)           // leading whitespace = $2
        ([*+-]|\d+[.]) [ \t]+     // list marker = $3
        ([^\r]+?            // list item text   = $4
        (\n{1,2}))
        (?= \n* (~0 | \2 ([*+-]|\d+[.]) [ \t]+))
      /gm, function(){...});
    */
      list_str = list_str.replace(/(\n)?(^[ \t]*)([*+-]|\d+[.])[ \t]+([^\r]+?(\n{1,2}))(?=\n*(~0|\2([*+-]|\d+[.])[ \t]+))/gm, function (wholeMatch, m1, m2, m3, m4) {
        var item = m4;
        var leading_line = m1;
        var leading_space = m2;
        if (leading_line || item.search(/\n{2,}/) > -1) {
          item = _RunBlockGamut(_Outdent(item));
        } else {
          // Recursion for sub-lists:
          item = _DoLists(_Outdent(item));
          item = item.replace(/\n$/, '');
          // chomp(item)
          item = _RunSpanGamut(item);
        }
        return '<li>' + item + '</li>\n';
      });
      // attacklab: strip sentinel
      list_str = list_str.replace(/~0/g, '');
      g_list_level--;
      return list_str;
    };
    var _DoCodeBlocks = function (text) {
      //
      //  Process Markdown `<pre><code>` blocks.
      //
      /*
      text = text.replace(text,
        /(?:\n\n|^)
        (               // $1 = the code block -- one or more lines, starting with a space/tab
          (?:
            (?:[ ]{4}|\t)     // Lines must start with a tab or a tab-width of spaces - attacklab: g_tab_width
            .*\n+
          )+
        )
        (\n*[ ]{0,3}[^ \t\n]|(?=~0))  // attacklab: g_tab_width
      /g,function(){...});
    */
      // attacklab: sentinel workarounds for lack of \A and \Z, safari\khtml bug
      text += '~0';
      text = text.replace(/(?:\n\n|^)((?:(?:[ ]{4}|\t).*\n+)+)(\n*[ ]{0,3}[^ \t\n]|(?=~0))/g, function (wholeMatch, m1, m2) {
        var codeblock = m1;
        var nextChar = m2;
        codeblock = _EncodeCode(_Outdent(codeblock));
        codeblock = _Detab(codeblock);
        codeblock = codeblock.replace(/^\n+/g, '');
        // trim leading newlines
        codeblock = codeblock.replace(/\n+$/g, '');
        // trim trailing whitespace
        codeblock = '<pre><code>' + codeblock + '\n</code></pre>';
        return hashBlock(codeblock) + nextChar;
      });
      // attacklab: strip sentinel
      text = text.replace(/~0/, '');
      return text;
    };
    var _DoGithubCodeBlocks = function (text) {
      //
      //  Process Github-style code blocks
      //  Example:
      //  ```ruby
      //  def hello_world(x)
      //    puts "Hello, #{x}"
      //  end
      //  ```
      //
      // attacklab: sentinel workarounds for lack of \A and \Z, safari\khtml bug
      text += '~0';
      text = text.replace(/(?:^|\n)```(.*)\n([\s\S]*?)\n```/g, function (wholeMatch, m1, m2) {
        var language = m1;
        var codeblock = m2;
        codeblock = _EncodeCode(codeblock);
        codeblock = _Detab(codeblock);
        codeblock = codeblock.replace(/^\n+/g, '');
        // trim leading newlines
        codeblock = codeblock.replace(/\n+$/g, '');
        // trim trailing whitespace
        codeblock = '<pre><code' + (language ? ' class="' + language + '"' : '') + '>' + codeblock + '\n</code></pre>';
        return hashBlock(codeblock);
      });
      // attacklab: strip sentinel
      text = text.replace(/~0/, '');
      return text;
    };
    var hashBlock = function (text) {
      text = text.replace(/(^\n+|\n+$)/g, '');
      return '\n\n~K' + (g_html_blocks.push(text) - 1) + 'K\n\n';
    };
    var _DoCodeSpans = function (text) {
      //
      //   *  Backtick quotes are used for <code></code> spans.
      //
      //   *  You can use multiple backticks as the delimiters if you want to
      //   include literal backticks in the code span. So, this input:
      //
      //     Just type ``foo `bar` baz`` at the prompt.
      //
      //     Will translate to:
      //
      //     <p>Just type <code>foo `bar` baz</code> at the prompt.</p>
      //
      //  There's no arbitrary limit to the number of backticks you
      //  can use as delimters. If you need three consecutive backticks
      //  in your code, use four for delimiters, etc.
      //
      //  *  You can use spaces to get literal backticks at the edges:
      //
      //     ... type `` `bar` `` ...
      //
      //     Turns to:
      //
      //     ... type <code>`bar`</code> ...
      //
      /*
      text = text.replace(/
        (^|[^\\])         // Character before opening ` can't be a backslash
        (`+)            // $2 = Opening run of `
        (             // $3 = The code block
          [^\r]*?
          [^`]          // attacklab: work around lack of lookbehind
        )
        \2              // Matching closer
        (?!`)
      /gm, function(){...});
    */
      text = text.replace(/(^|[^\\])(`+)([^\r]*?[^`])\2(?!`)/gm, function (wholeMatch, m1, m2, m3, m4) {
        var c = m3;
        c = c.replace(/^([ \t]*)/g, '');
        // leading whitespace
        c = c.replace(/[ \t]*$/g, '');
        // trailing whitespace
        c = _EncodeCode(c);
        return m1 + '<code>' + c + '</code>';
      });
      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) {
      // <strong> must go first:
      text = text.replace(/(\*\*|__)(?=\S)([^\r]*?\S[*_]*)\1/g, '<strong>$2</strong>');
      text = text.replace(/(\*|_)(?=\S)([^\r]*?\S)\1/g, '<em>$2</em>');
      return text;
    };
    var _DoBlockQuotes = function (text) {
      /*
      text = text.replace(/
      (               // Wrap whole match in $1
        (
          ^[ \t]*>[ \t]?      // '>' at the start of a line
          .+\n          // rest of the first line
          (.+\n)*         // subsequent consecutive lines
          \n*           // blanks
        )+
      )
      /gm, function(){...});
    */
      text = text.replace(/((^[ \t]*>[ \t]?.+\n(.+\n)*\n*)+)/gm, function (wholeMatch, m1) {
        var bq = m1;
        // attacklab: hack around Konqueror 3.5.4 bug:
        // "----------bug".replace(/^-/g,"") == "bug"
        bq = bq.replace(/^[ \t]*>[ \t]?/gm, '~0');
        // trim one level of quoting
        // attacklab: clean up hack
        bq = bq.replace(/~0/g, '');
        bq = bq.replace(/^[ \t]+$/gm, '');
        // trim whitespace-only lines
        bq = _RunBlockGamut(bq);
        // recurse
        bq = bq.replace(/(^|\n)/g, '$1  ');
        // These leading spaces screw with <pre> content, so we need to fix that:
        bq = bq.replace(/(\s*<pre>[^\r]+?<\/pre>)/gm, function (wholeMatch, m1) {
          var pre = m1;
          // attacklab: hack around Konqueror 3.5.4 bug:
          pre = pre.replace(/^  /gm, '~0');
          pre = pre.replace(/~0/g, '');
          return pre;
        });
        return hashBlock('<blockquote>\n' + bq + '\n</blockquote>');
      });
      return text;
    };
    var _FormParagraphs = function (text) {
      //
      //  Params:
      //    $text - string to process with html <p> tags
      //
      // Strip leading and trailing lines:
      text = text.replace(/^\n+/g, '');
      text = text.replace(/\n+$/g, '');
      var grafs = text.split(/\n{2,}/g);
      var grafsOut = [];
      //
      // 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 (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: <address@domain.foo>
      /*
      text = text.replace(/
        <
        (?:mailto:)?
        (
          [-.\w]+
          \@
          [-a-z0-9]+(\.[-a-z0-9]+)*\.[a-z]+
        )
        >
      /gi, _DoAutoLinks_callback());
    */
      text = text.replace(/<(?:mailto:)?([-.\w]+\@[-a-z0-9]+(\.[-a-z0-9]+)*\.[a-z]+)>/gi, function (wholeMatch, m1) {
        return _EncodeEmailAddress(_UnescapeSpecialChars(m1));
      });
      return text;
    };
    var _EncodeEmailAddress = function (addr) {
      //
      //  Input: an email address, e.g. "foo@example.com"
      //
      //  Output: the email address as a mailto link, with each character
      //  of the address encoded as either a decimal or hex entity, in
      //  the hopes of foiling most address harvesting spam bots. E.g.:
      //
      //  <a href="&#x6D;&#97;&#105;&#108;&#x74;&#111;:&#102;&#111;&#111;&#64;&#101;
      //     x&#x61;&#109;&#x70;&#108;&#x65;&#x2E;&#99;&#111;&#109;">&#102;&#111;&#111;
      //     &#64;&#101;x&#x61;&#109;&#x70;&#108;&#x65;&#x2E;&#99;&#111;&#109;</a>
      //
      //  Based on a filter by Matthew Wickline, posted to the BBEdit-Talk
      //  mailing list: <http://tinyurl.com/yu7ue>
      //
      var encode = [
          function (ch) {
            return '&#' + ch.charCodeAt(0) + ';';
          },
          function (ch) {
            return '&#x' + ch.charCodeAt(0).toString(16) + ';';
          },
          function (ch) {
            return ch;
          }
        ];
      addr = 'mailto:' + addr;
      addr = addr.replace(/./g, function (ch) {
        if (ch == '@') {
          // this *must* be encoded. I insist.
          ch = encode[Math.floor(Math.random() * 2)](ch);
        } else if (ch != ':') {
          // leave ':' alone (to spot mailto: later)
          var r = Math.random();
          // roughly 10% raw, 45% hex, 45% dec
          ch = r > 0.9 ? encode[2](ch) : r > 0.45 ? encode[1](ch) : encode[0](ch);
        }
        return ch;
      });
      addr = '<a href="' + addr + '">' + addr + '</a>';
      addr = addr.replace(/">.+:/g, '">');
      // strip the mailto: from the visible part
      return addr;
    };
    var _UnescapeSpecialChars = function (text) {
      //
      // Swap back in all the special characters we've hidden.
      //
      text = text.replace(/~E(\d+)E/g, function (wholeMatch, m1) {
        var charCodeToReplace = parseInt(m1);
        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 module !== 'undefined')
    module.exports = Showdown;
  // stolen from AMD branch of underscore
  // AMD define happens at the end for compatibility with AMD loaders
  // that don't enforce next-turn semantics on modules.
  if (typeof define === 'function' && define.amd) {
    define(function () {
      return Showdown;
    });
  }