showdown.js

//
// 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/>
//
// 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.
//

/*jslint browser:true, white:false, onevar:false, nomen:false, regexp:false, undef:false,
         eqeqeq:false, plusplus:false, bitwise:false */
/*globals window */

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


//
// Attacklab namespace
//
window['Attacklab'] = window['Attacklab'] || {};

//
// Showdown namespace
//
window['Attacklab']['showdown'] = window['Attacklab']['showdown'] || {};

/**
 * Markdown converter
 *
 * Wraps all 'globals' so that the only public function is `makeHtml()`
 *
 * @constructor
 */
window['Attacklab']['showdown']['converter'] = function () {

//
// Globals:
//

// Global hashes, used by various utility routines
var g_urls;
var g_titles;
var g_html_blocks;

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

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

    // Clear the global hashes. If we don't clear these, you get conflicts
    // from other articles when generating a page which contains more than
    // one article (e.g. an index page that shows the N most recent
    // articles):
    g_urls = [];
    g_titles = [];
    g_html_blocks = [];

    // attacklab: Replace ~ with ~T
    // This lets us use tilde as an escape char to avoid md5 hashes
    // The choice of character is arbitray; anything that isn't
    // magic in Markdown will work.
    text = text.replace(/~/g,"~T");

    // attacklab: Replace $ with ~D
    // RegExp interprets $ as a special character
    // when it's in a replacement string
    text = text.replace(/\$/g,"~D");

    // Standardize line endings
    text = text.replace(/\r\n/g,"\n"); // DOS to Unix
    text = text.replace(/\r/g,"\n"); // Mac to Unix

    // Make sure text begins and ends with a couple of newlines:
    text = "\n\n" + text + "\n\n";

    // Convert all tabs to spaces.
    text = _Detab(text);

    // Strip any lines consisting only of spaces and tabs.
    // This makes subsequent regexen easier to write, because we can
    // match consecutive blank lines with /\n+/ instead of something
    // contorted like /[ \t]*\n+/ .
    text = text.replace(/^[ \t]+$/mg,"");

    // Turn block-level HTML blocks into hash entries
    text = _HashHTMLBlocks(text);

    // Strip link definitions, store in hashes.
    text = _StripLinkDefinitions(text);

    text = _RunBlockGamut(text);

    text = _UnescapeSpecialChars(text);

    // attacklab: Restore dollar signs
    text = text.replace(/~D/g,"$$");

    // attacklab: Restore tildes
    text = text.replace(/~T/g,"~");

    return text;
};

var _StripLinkDefinitions = function(orig) {
//
// Strips link definitions from text, stores the URLs and titles in
// hash references.
//

    // Link defs are in the form: ^[id]: url "optional title"

    /*
        var text = text.replace(/
                ^[ ]{0,3}\[(.+)\]:  // id = $1  attacklab: g_tab_width - 1
                  [ \t]*
                  \n?               // maybe *one* newline
                  [ \t]*
                <?(\S+?)>?          // url = $2
                  [ \t]*
                  \n?               // maybe one newline
                  [ \t]*
                (?:
                  (\n*)             // any lines skipped = $3 attacklab: lookbehind removed
                  ["(]
                  (.+?)             // title = $4
                  [")]
                  [ \t]*
                )?                  // title is optional
                (?:\n+|$)
              /gm,
              function(){...});
    */
    var text = orig.replace(/^[ ]{0,3}\[(.+)\]:[ \t]*\n?[ \t]*<?(\S+?)>?[ \t]*\n?[ \t]*(?:(\n*)["(](.+?)[")][ \t]*)?(?:\n+)/gm,
        function (wholeMatch,m1,m2,m3,m4) {
            m1 = m1.toLowerCase();
            g_urls[m1] = _EncodeAmpsAndAngles(m2);  // Link IDs are case-insensitive
            if (m3) {
                // Oops, found blank lines, so it's not a title.
                // Put back the parenthetical statement we stole.
                return m3+m4;
            } else if (m4) {
                g_titles[m1] = m4.replace(/"/g,"&quot;");
            }
            
            // Completely remove the definition from the text
            return "";
        }
    );

    return text;
};

var _HashHTMLBlocks = function(text) {
    // attacklab: Double up blank lines to reduce lookaround
    text = text.replace(/\n/g,"\n\n");

    // Hashify HTML blocks:
    // We only want to do this for block-level HTML tags, such as headers,
    // lists, and tables. That's because we still want to wrap <p>s around
    // "paragraphs" that are wrapped in non-block-level tags, such as anchors,
    // phrase emphasis, and spans. The list of tags we're looking for is
    // hard-coded:
    var block_tags_a = "p|div|h[1-6]|blockquote|pre|table|dl|ol|ul|script|noscript|form|fieldset|iframe|math|ins|del";
    var block_tags_b = "p|div|h[1-6]|blockquote|pre|table|dl|ol|ul|script|noscript|form|fieldset|iframe|math";

    // First, look for nested blocks, e.g.:
    //   <div>
    //     <div>
    //     tags for inner block must be indented.
    //     </div>
    //   </div>
    //
    // The outermost tags must start at the left margin for this to match, and
    // the inner nested divs must be indented.
    // We need to do this before the next, more liberal match, because the next
    // match will start at the first `<div>` and stop at the first `</div>`.

    // attacklab: This regex can be expensive when it fails.
    /*
        var text = text.replace(/
        (                       // save in $1
            ^                   // start of line  (with /m)
            <($block_tags_a)    // start tag = $2
            \b                  // word break
                                // attacklab: hack around khtml/pcre bug...
            [^\r]*?\n           // any number of lines, minimally matching
            </\2>               // the matching end tag
            [ \t]*              // trailing spaces/tabs
            (?=\n+)             // followed by a newline
        )                       // attacklab: there are sentinel newlines at end of document
        /gm,function(){...}};
    */
    text = text.replace(/^(<(p|div|h[1-6]|blockquote|pre|table|dl|ol|ul|script|noscript|form|fieldset|iframe|math|ins|del)\b[^\r]*?\n<\/\2>[ \t]*(?=\n+))/gm,hashElement);

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

    /*
        var text = text.replace(/
        (                       // save in $1
            ^                   // start of line  (with /m)
            <($block_tags_b)    // start tag = $2
            \b                  // word break
                                // attacklab: hack around khtml/pcre bug...
            [^\r]*?             // any number of lines, minimally matching
            .*</\2>             // the matching end tag
            [ \t]*              // trailing spaces/tabs
            (?=\n+)             // followed by a newline
        )                       // attacklab: there are sentinel newlines at end of document
        /gm,function(){...}};
    */
    text = text.replace(/^(<(p|div|h[1-6]|blockquote|pre|table|dl|ol|ul|script|noscript|form|fieldset|iframe|math)\b[^\r]*?.*<\/\2>[ \t]*(?=\n+)\n)/gm,hashElement);

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

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

    // Special case for standalone HTML comments:

    /*
        text = text.replace(/
        (                       // save in $1
            \n\n                // Starting after a blank line
            [ ]{0,3}            // attacklab: g_tab_width - 1
            <!
            (--[^\r]*?--\s*)+
            >
            [ \t]*
            (?=\n{2,})          // followed by a blank line
        )
        /g,hashElement);
    */
    text = text.replace(/(\n\n[ ]{0,3}<!(--[^\r]*?--\s*)+>[ \t]*(?=\n{2,}))/g,hashElement);

    // PHP and ASP-style processor instructions (<?...?> and <%...%>)

    /*
        text = text.replace(/
        (?:
            \n\n                // Starting after a blank line
        )
        (                       // save in $1
            [ ]{0,3}            // attacklab: g_tab_width - 1
            (?:
                <([?%])         // $2
                [^\r]*?
                \2>
            )
            [ \t]*
            (?=\n{2,})          // followed by a blank line
        )
        /g,hashElement);
    */
    text = text.replace(/(?:\n\n)([ ]{0,3}(?:<([?%])[^\r]*?\2>)[ \t]*(?=\n{2,}))/g,hashElement);

    // attacklab: Undo double lines (see comment at top of this function)
    text = text.replace(/\n\n/g,"\n");
    return text;
};

var hashElement = function(wholeMatch,m1) {
    var blockText = m1;

    // Undo double lines
    blockText = blockText.replace(/\n\n/g,"\n");
    blockText = blockText.replace(/^\n/,"");
    
    // strip trailing blank lines
    blockText = blockText.replace(/\n+$/g,"");
    
    // Replace the element text with a marker ("~KxK" where x is its key)
    blockText = "\n\n~K" + (g_html_blocks.push(blockText)-1) + "K\n\n";
    
    return blockText;
};

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

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

    text = _DoLists(text);
    text = _DoCodeBlocks(text);
    text = _DoBlockQuotes(text);

    // We already ran _HashHTMLBlocks() before, in Markdown(), but that
    // was to escape raw HTML in the original Markdown source. This time,
    // we're escaping the markup we've just created, so that we don't wrap
    // <p> tags around block-level tags.
    text = _HashHTMLBlocks(text);
    text = _FormParagraphs(text);

    return text;
};


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

    text = _DoCodeSpans(text);
    text = _EscapeSpecialCharsWithinTagAttributes(text);
    text = _EncodeBackslashEscapes(text);

    // Process anchor and image tags. Images must come first,
    // because ![foo][f] looks like an anchor.
    text = _DoImages(text);
    text = _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>" + _RunSpanGamut(m1) + "</h1>");});

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

    // atx-style headers:
    //  # Header 1
    //  ## Header 2
    //  ## Header 2 with closing hashes ##
    //  ...
    //  ###### Header 6
    //

    /*
        text = text.replace(/
            ^(\#{1,6})              // $1 = string of #'s
            [ \t]*
            (.+?)                   // $2 = Header text
            [ \t]*
            \#*                     // optional closing #'s (not counted)
            \n+
        /gm, function() {...});
    */

    text = text.replace(/^(\#{1,6})[ \t]*(.+?)[ \t]*\#*\n+/gm,
        function(wholeMatch,m1,m2) {
            var h_level = m1.length;
            return hashBlock("<h" + h_level + ">" + _RunSpanGamut(m2) + "</h" + h_level + ">");
        });

    return text;
};

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

var _DoLists = function(text) {
//
// Form HTML ordered (numbered) and unordered (bulleted) lists.
//

    // attacklab: add sentinel to hack around khtml/safari bug:
    // http://bugs.webkit.org/show_bug.cgi?id=11231
    text += "~0";

    // Re-usable pattern to match any entirel ul or ol list:

    /*
        var whole_list = /
        (                                   // $1 = whole list
            (                               // $2
                [ ]{0,3}                    // attacklab: g_tab_width - 1
                ([*+-]|\d+[.])              // $3 = first list item marker
                [ \t]+
            )
            [^\r]+?
            (                               // $4
                ~0                          // sentinel for workaround; should be $
            |
                \n{2,}
                (?=\S)
                (?!                         // Negative lookahead for another list item marker
                    [ \t]*
                    (?:[*+-]|\d+[.])[ \t]+
                )
            )
        )/g
    */
    var whole_list = /^(([ ]{0,3}([*+\-]|\d+[.])[ \t]+)[^\r]+?(~0|\n{2,}(?=\S)(?![ \t]*(?:[*+\-]|\d+[.])[ \t]+)))/gm;

    if (g_list_level) {
        text = text.replace(whole_list,function(wholeMatch,m1,m2) {
            var list = m1;
            var list_type = (m2.search(/[*+\-]/g)>-1) ? "ul" : "ol";

            // Turn double returns into triple returns, so that we can make a
            // paragraph for the last item in a list, if necessary:
            list = list.replace(/\n{2,}/g,"\n\n\n");
            var result = _ProcessListItems(list);
    
            // Trim any trailing whitespace, to put the closing `</$list_type>`
            // up on the preceding line, to get it past the current stupid
            // HTML block parser. This is a hack to work around the terrible
            // hack that is the HTML block parser.
            result = result.replace(/\s+$/,"");
            result = "<"+list_type+">" + result + "</"+list_type+">\n";
            return result;
        });
    } else {
        whole_list = /(\n\n|^\n?)(([ ]{0,3}([*+\-]|\d+[.])[ \t]+)[^\r]+?(~0|\n{2,}(?=\S)(?![ \t]*(?:[*+\-]|\d+[.])[ \t]+)))/g;
        text = text.replace(whole_list,function(wholeMatch,m1,m2,m3) {
            var runup = m1;
            var list = m2;

            var list_type = (m3.search(/[*+\-]/g)>-1) ? "ul" : "ol";
            // Turn double returns into triple returns, so that we can make a
            // paragraph for the last item in a list, if necessary:
            list = list.replace(/\n{2,}/g,"\n\n\n");
            var result = _ProcessListItems(list);
            result = runup + "<"+list_type+">\n" + result + "</"+list_type+">\n";   
            return result;
        });
    }

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

    return text;
};

_ProcessListItems = function(list_str) {
//
//  Process the contents of a single ordered or unordered list, splitting it
//  into individual list items.
//
    // The $g_list_level global keeps track of when we're inside a list.
    // Each time we enter a list, we increment it; when we leave a list,
    // we decrement. If it's zero, we're not in a list anymore.
    //
    // We do this because when we're not inside a list, we want to treat
    // something like this:
    //
    //    I recommend upgrading to version
    //    8. Oops, now this line is treated
    //    as a sub-list.
    //
    // As a single paragraph, despite the fact that the second line starts
    // with a digit-period-space sequence.
    //
    // Whereas when we're inside a list (or sub-list), that line will be
    // treated as the start of a sub-list. What a kludge, huh? This is
    // an aspect of Markdown's syntax that's hard to parse perfectly
    // without resorting to mind-reading. Perhaps the solution is to
    // change the syntax rules such that sub-lists must start with a
    // starting cardinal number; e.g. "1." or "a.".

    g_list_level++;

    // trim trailing blank lines:
    list_str = list_str.replace(/\n{2,}$/,"\n");

    // attacklab: add sentinel to emulate \z
    list_str += "~0";

    /*
        list_str = list_str.replace(/
            (\n)?                           // leading line = $1
            (^[ \t]*)                       // leading whitespace = $2
            ([*+-]|\d+[.]) [ \t]+           // list marker = $3
            ([^\r]+?                        // list item text   = $4
            (\n{1,2}))
            (?= \n* (~0 | \2 ([*+-]|\d+[.]) [ \t]+))
        /gm, function(){...});
    */
    list_str = list_str.replace(/(\n)?(^[ \t]*)([*+\-]|\d+[.])[ \t]+([^\r]+?(\n{1,2}))(?=\n*(~0|\2([*+\-]|\d+[.])[ \t]+))/gm,
        function(wholeMatch,m1,m2,m3,m4){
            var item = m4;
            var leading_line = m1;
            var leading_space = m2;

            if (leading_line || (item.search(/\n{2,}/)>-1)) {
                item = _RunBlockGamut(_Outdent(item));
            }
            else {
                // Recursion for sub-lists:
                item = _DoLists(_Outdent(item));
                item = item.replace(/\n$/,""); // chomp(item)
                item = _RunSpanGamut(item);
            }

            return  "<li>" + item + "</li>\n";
        }
    );

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

    g_list_level--;
    return list_str;
};


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

    /*
        text = text.replace(text,
            /(?:\n\n|^)
            (                               // $1 = the code block -- one or more lines, starting with a space/tab
                (?:
                    (?:[ ]{4}|\t)           // Lines must start with a tab or a tab-width of spaces - attacklab: g_tab_width
                    .*\n+
                )+
            )
            (\n*[ ]{0,3}[^ \t\n]|(?=~0))    // attacklab: g_tab_width
        /g,function(){...});
    */

    // attacklab: sentinel workarounds for lack of \A and \Z, safari\khtml bug
    text += "~0";
    
    text = text.replace(/(?:\n\n|^)((?:(?:[ ]{4}|\t).*\n+)+)(\n*[ ]{0,3}[^ \t\n]|(?=~0))/g,
        function(wholeMatch,m1,m2) {
            var codeblock = m1;
            var nextChar = m2;
        
            codeblock = _EncodeCode( _Outdent(codeblock));
            codeblock = _Detab(codeblock);
            codeblock = codeblock.replace(/^\n+/g,""); // trim leading newlines
            codeblock = codeblock.replace(/\n+$/g,""); // trim trailing whitespace

            codeblock = "<pre><code>" + codeblock + "\n</code></pre>";

            return hashBlock(codeblock) + nextChar;
        }
    );

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

    return text;
};

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


var _DoCodeSpans = function(text) {
//
//   *  Backtick quotes are used for <code></code> spans.
// 
//   *  You can use multiple backticks as the delimiters if you want to
//   include literal backticks in the code span. So, this input:
//   
//       Just type ``foo `bar` baz`` at the prompt.
//   
//     Will translate to:
//   
//       <p>Just type <code>foo `bar` baz</code> at the prompt.</p>
//   
//  There's no arbitrary limit to the number of backticks you
//  can use as delimters. If you need three consecutive backticks
//  in your code, use four for delimiters, etc.
//
//  *  You can use spaces to get literal backticks at the edges:
//   
//       ... type `` `bar` `` ...
//   
//     Turns to:
//   
//       ... type <code>`bar`</code> ...
//

    /*
        text = text.replace(/
            (^|[^\\])                   // Character before opening ` can't be a backslash
            (`+)                        // $2 = Opening run of `
            (                           // $3 = The code block
                [^\r]*?
                [^`]                    // attacklab: work around lack of lookbehind
            )
            \2                          // Matching closer
            (?!`)
        /gm, function(){...});
    */

    text = text.replace(/(^|[^\\])(`+)([^\r]*?[^`])\2(?!`)/gm,
        function(wholeMatch,m1,m2,m3,m4) {
            var c = m3;
            c = c.replace(/^([ \t]*)/g,""); // leading whitespace
            c = c.replace(/[ \t]*$/g,"");   // trailing whitespace
            c = _EncodeCode(c);
            return m1+"<code>"+c+"</code>";
        });

    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(/^[ ]{2}/mg,"~0");
                    pre = pre.replace(/~0/g,"");
                    return pre;
                });
            
            return hashBlock("<blockquote>\n" + bq + "\n</blockquote>");
        });
    return text;
};


var _FormParagraphs = function(text) {
//
//  Params:
//    $text - string to process with html <p> tags
//
    var i;
    
    // 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 (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 (i=0; i<end; i++) {
        // if this is a marker for an html block...
        var results;
        
        while ((results = /~K(\d+)K/.exec(grafsOut[i])) !== null) {
            var blockText = g_html_blocks[results[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>
//

    // attacklab: why can't javascript speak hex?
    function char2hex(ch) {
        var hexDigits = '0123456789ABCDEF';
        var dec = ch.charCodeAt(0);
        return(hexDigits.charAt(dec>>4) + hexDigits.charAt(dec&15));
    }

    var encode = [
        function(ch){return "&#"+ch.charCodeAt(0)+";";},
        function(ch){return "&#x"+char2hex(ch)+";";},
        function(ch){return ch;}
    ];

    addr = "mailto:" + addr;

    addr = addr.replace(/./g, function(ch) {
        if (ch == "@") {
            // this *must* be encoded. I insist.
            ch = encode[Math.floor(Math.random()*2)](ch);
        } else if (ch !=":") {
            // leave ':' alone (to spot mailto: later)
            var r = Math.random();
            // roughly 10% raw, 45% hex, 45% dec
            ch =  (
                    r > 0.9  ?   encode[2](ch)   :
                    r > 0.45 ?   encode[1](ch)   :
                                encode[0](ch)
                );
        }
        return ch;
    });

    addr = "<a href=\"" + addr + "\">" + addr + "</a>";
    addr = addr.replace(/">.+:/g,"\">"); // strip the mailto: from the visible part

    return addr;
};


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


var _Outdent = function(text) {
//
// Remove one level of line-leading tabs or spaces
//

    // attacklab: hack around Konqueror 3.5.4 bug:
    // "----------bug".replace(/^-/g,"") == "bug"

    text = text.replace(/^(\t|[ ]{1,4})/gm,"~0"); // attacklab: g_tab_width

    // attacklab: clean up hack
    text = text.replace(/~0/g,"");

    return text;
};

var _Detab = function(text) {
// attacklab: Detab's completely rewritten for speed.
// In perl we could fix it by anchoring the regexp with \G.
// In javascript we're less fortunate.

    // expand first n-1 tabs
    text = text.replace(/\t(?=\t)/g,"    "); // attacklab: g_tab_width

    // replace the nth with two sentinels
    text = text.replace(/\t/g,"~A~B");

    // use the sentinel to anchor our regex so it doesn't explode
    text = text.replace(/~B(.+?)~A/g,
        function(wholeMatch,m1,m2) {
            var leadingText = m1;
            var numSpaces = 4 - leadingText.length % 4;  // attacklab: g_tab_width

            // there *must* be a better way to do this:
            for (var i=0; i<numSpaces; i++) {
                leadingText += " ";
            }

            return leadingText;
        }
    );

    // clean up sentinels
    text = text.replace(/~A/g,"    ");  // attacklab: g_tab_width
    text = text.replace(/~B/g,"");

    return text;
};


//
//  attacklab: Utility functions
//


var escapeCharacters = function(text, charsToEscape, afterBackslash) {
    // First we have to escape the escape characters so that
    // we can build a character class out of them
    var regexString = "([" + charsToEscape.replace(/([\[\]\\])/g,"\\$1") + "])";

    if (afterBackslash) {
        regexString = "\\\\" + regexString;
    }

    var regex = new RegExp(regexString,"g");
    text = text.replace(regex,escapeCharacters_callback);

    return text;
};


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

}; // end of Attacklab.showdown.converter


// Version 0.9 used the Showdown namespace instead of Attacklab.showdown
// The old namespace is deprecated, but we'll support it for now:
window['Showdown'] = window['Attacklab']['showdown'];

// If anyone's interested, tell the world that this file's been loaded
if (window['Attacklab']['fileLoaded']) {
    window['Attacklab']['fileLoaded']("showdown.js");
}