gruber.js

if (typeof define !== 'function') { var define = require('amdefine')(module) }
define(['../markdown_helpers', './dialect_helpers', '../parser'], function (MarkdownHelpers, DialectHelpers, Markdown) {


  var forEach = MarkdownHelpers.forEach,
      extract_attr = MarkdownHelpers.extract_attr,
      mk_block = MarkdownHelpers.mk_block,
      isEmpty = MarkdownHelpers.isEmpty,
      inline_until_char = DialectHelpers.inline_until_char;

  /**
   * Gruber dialect
   *
   * The default dialect that follows the rules set out by John Gruber's
   * markdown.pl as closely as possible. Well actually we follow the behaviour of
   * that script which in some places is not exactly what the syntax web page
   * says.
   **/
  var Gruber = {
    block: {
      atxHeader: function atxHeader( block, next ) {
        var m = block.match( /^(#{1,6})\s*(.*?)\s*#*\s*(?:\n|$)/ );

        if ( !m )
          return undefined;

        var header = [ "header", { level: m[ 1 ].length } ];
        Array.prototype.push.apply(header, this.processInline(m[ 2 ]));

        if ( m[0].length < block.length )
          next.unshift( mk_block( block.substr( m[0].length ), block.trailing, block.lineNumber + 2 ) );

        return [ header ];
      },

      setextHeader: function setextHeader( block, next ) {
        var m = block.match( /^(.*)\n([-=])\2\2+(?:\n|$)/ );

        if ( !m )
          return undefined;

        var level = ( m[ 2 ] === "=" ) ? 1 : 2,
            header = [ "header", { level : level } ].concat( this.processInline(m[ 1 ]) );

        if ( m[0].length < block.length )
          next.unshift( mk_block( block.substr( m[0].length ), block.trailing, block.lineNumber + 2 ) );

        return [ header ];
      },

      code: function code( block, next ) {
        // |    Foo
        // |bar
        // should be a code block followed by a paragraph. Fun
        //
        // There might also be adjacent code block to merge.

        var ret = [],
            re = /^(?: {0,3}\t| {4})(.*)\n?/;

        // 4 spaces + content
        if ( !block.match( re ) )
          return undefined;

        block_search:
        do {
          // Now pull out the rest of the lines
          var b = this.loop_re_over_block(
                    re, block.valueOf(), function( m ) { ret.push( m[1] ); } );

          if ( b.length ) {
            // Case alluded to in first comment. push it back on as a new block
            next.unshift( mk_block(b, block.trailing) );
            break block_search;
          }
          else if ( next.length ) {
            // Check the next block - it might be code too
            if ( !next[0].match( re ) )
              break block_search;

            // Pull how how many blanks lines follow - minus two to account for .join
            ret.push ( block.trailing.replace(/[^\n]/g, "").substring(2) );

            block = next.shift();
          }
          else {
            break block_search;
          }
        } while ( true );

        return [ [ "code_block", ret.join("\n") ] ];
      },

      horizRule: function horizRule( block, next ) {
        // this needs to find any hr in the block to handle abutting blocks
        var m = block.match( /^(?:([\s\S]*?)\n)?[ \t]*([-_*])(?:[ \t]*\2){2,}[ \t]*(?:\n([\s\S]*))?$/ );

        if ( !m )
          return undefined;

        var jsonml = [ [ "hr" ] ];

        // if there's a leading abutting block, process it
        if ( m[ 1 ] ) {
          var contained = mk_block( m[ 1 ], "", block.lineNumber );
          jsonml.unshift.apply( jsonml, this.toTree( contained, [] ) );
        }

        // if there's a trailing abutting block, stick it into next
        if ( m[ 3 ] )
          next.unshift( mk_block( m[ 3 ], block.trailing, block.lineNumber + 1 ) );

        return jsonml;
      },

      // There are two types of lists. Tight and loose. Tight lists have no whitespace
      // between the items (and result in text just in the <li>) and loose lists,
      // which have an empty line between list items, resulting in (one or more)
      // paragraphs inside the <li>.
      //
      // There are all sorts weird edge cases about the original markdown.pl's
      // handling of lists:
      //
      // * Nested lists are supposed to be indented by four chars per level. But
      //   if they aren't, you can get a nested list by indenting by less than
      //   four so long as the indent doesn't match an indent of an existing list
      //   item in the 'nest stack'.
      //
      // * The type of the list (bullet or number) is controlled just by the
      //    first item at the indent. Subsequent changes are ignored unless they
      //    are for nested lists
      //
      lists: (function( ) {
        // Use a closure to hide a few variables.
        var any_list = "[*+-]|\\d+\\.",
            bullet_list = /[*+-]/,
            // Capture leading indent as it matters for determining nested lists.
            is_list_re = new RegExp( "^( {0,3})(" + any_list + ")[ \t]+" ),
            indent_re = "(?: {0,3}\\t| {4})";

        // TODO: Cache this regexp for certain depths.
        // Create a regexp suitable for matching an li for a given stack depth
        function regex_for_depth( depth ) {

          return new RegExp(
            // m[1] = indent, m[2] = list_type
            "(?:^(" + indent_re + "{0," + depth + "} {0,3})(" + any_list + ")\\s+)|" +
            // m[3] = cont
            "(^" + indent_re + "{0," + (depth-1) + "}[ ]{0,4})"
          );
        }
        function expand_tab( input ) {
          return input.replace( / {0,3}\t/g, "    " );
        }

        // Add inline content `inline` to `li`. inline comes from processInline
        // so is an array of content
        function add(li, loose, inline, nl) {
          if ( loose ) {
            li.push( [ "para" ].concat(inline) );
            return;
          }
          // Hmmm, should this be any block level element or just paras?
          var add_to = li[li.length -1] instanceof Array && li[li.length - 1][0] === "para"
                     ? li[li.length -1]
                     : li;

          // If there is already some content in this list, add the new line in
          if ( nl && li.length > 1 )
            inline.unshift(nl);

          for ( var i = 0; i < inline.length; i++ ) {
            var what = inline[i],
                is_str = typeof what === "string";
            if ( is_str && add_to.length > 1 && typeof add_to[add_to.length-1] === "string" )
              add_to[ add_to.length-1 ] += what;
            else
              add_to.push( what );
          }
        }

        // contained means have an indent greater than the current one. On
        // *every* line in the block
        function get_contained_blocks( depth, blocks ) {

          var re = new RegExp( "^(" + indent_re + "{" + depth + "}.*?\\n?)*$" ),
              replace = new RegExp("^" + indent_re + "{" + depth + "}", "gm"),
              ret = [];

          while ( blocks.length > 0 ) {
            if ( re.exec( blocks[0] ) ) {
              var b = blocks.shift(),
                  // Now remove that indent
                  x = b.replace( replace, "");

              ret.push( mk_block( x, b.trailing, b.lineNumber ) );
            }
            else
              break;
          }
          return ret;
        }

        // passed to stack.forEach to turn list items up the stack into paras
        function paragraphify(s, i, stack) {
          var list = s.list;
          var last_li = list[list.length-1];

          if ( last_li[1] instanceof Array && last_li[1][0] === "para" )
            return;

          if ( i + 1 === stack.length ) {
            // Last stack frame
            // Keep the same array, but replace the contents
            last_li.push( ["para"].concat( last_li.splice(1, last_li.length - 1) ) );
          }
          else {
            var sublist = last_li.pop();
            last_li.push( ["para"].concat( last_li.splice(1, last_li.length - 1) ), sublist );
          }
        }

        // The matcher function
        return function( block, next ) {
          var m = block.match( is_list_re );
          if ( !m )
            return undefined;

          function make_list( m ) {
            var list = bullet_list.exec( m[2] )
                     ? ["bulletlist"]
                     : ["numberlist"];

            stack.push( { list: list, indent: m[1] } );
            return list;
          }


          var stack = [], // Stack of lists for nesting.
              list = make_list( m ),
              last_li,
              loose = false,
              ret = [ stack[0].list ],
              i;

          // Loop to search over block looking for inner block elements and loose lists
          loose_search:
          while ( true ) {
            // Split into lines preserving new lines at end of line
            var lines = block.split( /(?=\n)/ );

            // We have to grab all lines for a li and call processInline on them
            // once as there are some inline things that can span lines.
            var li_accumulate = "", nl = "";

            // Loop over the lines in this block looking for tight lists.
            tight_search:
            for ( var line_no = 0; line_no < lines.length; line_no++ ) {
              nl = "";
              var l = lines[line_no].replace(/^\n/, function(n) { nl = n; return ""; });


              // TODO: really should cache this
              var line_re = regex_for_depth( stack.length );

              m = l.match( line_re );
              //print( "line:", uneval(l), "\nline match:", uneval(m) );

              // We have a list item
              if ( m[1] !== undefined ) {
                // Process the previous list item, if any
                if ( li_accumulate.length ) {
                  add( last_li, loose, this.processInline( li_accumulate ), nl );
                  // Loose mode will have been dealt with. Reset it
                  loose = false;
                  li_accumulate = "";
                }

                m[1] = expand_tab( m[1] );
                var wanted_depth = Math.floor(m[1].length/4)+1;
                //print( "want:", wanted_depth, "stack:", stack.length);
                if ( wanted_depth > stack.length ) {
                  // Deep enough for a nested list outright
                  //print ( "new nested list" );
                  list = make_list( m );
                  last_li.push( list );
                  last_li = list[1] = [ "listitem" ];
                }
                else {
                  // We aren't deep enough to be strictly a new level. This is
                  // where Md.pl goes nuts. If the indent matches a level in the
                  // stack, put it there, else put it one deeper then the
                  // wanted_depth deserves.
                  var found = false;
                  for ( i = 0; i < stack.length; i++ ) {
                    if ( stack[ i ].indent !== m[1] )
                      continue;

                    list = stack[ i ].list;
                    stack.splice( i+1, stack.length - (i+1) );
                    found = true;
                    break;
                  }

                  if (!found) {
                    //print("not found. l:", uneval(l));
                    wanted_depth++;
                    if ( wanted_depth <= stack.length ) {
                      stack.splice(wanted_depth, stack.length - wanted_depth);
                      //print("Desired depth now", wanted_depth, "stack:", stack.length);
                      list = stack[wanted_depth-1].list;
                      //print("list:", uneval(list) );
                    }
                    else {
                      //print ("made new stack for messy indent");
                      list = make_list(m);
                      last_li.push(list);
                    }
                  }

                  //print( uneval(list), "last", list === stack[stack.length-1].list );
                  last_li = [ "listitem" ];
                  list.push(last_li);
                } // end depth of shenegains
                nl = "";
              }

              // Add content
              if ( l.length > m[0].length )
                li_accumulate += nl + l.substr( m[0].length );
            } // tight_search

            if ( li_accumulate.length ) {
              add( last_li, loose, this.processInline( li_accumulate ), nl );

              // Let's not creating a trailing \n after content in the li
              if(last_li[last_li.length-1] === "\n") {
                last_li.pop();
              }

              // Loose mode will have been dealt with. Reset it
              loose = false;
              li_accumulate = "";
            }

            // Look at the next block - we might have a loose list. Or an extra
            // paragraph for the current li
            var contained = get_contained_blocks( stack.length, next );

            // Deal with code blocks or properly nested lists
            if ( contained.length > 0 ) {
              // Make sure all listitems up the stack are paragraphs
              forEach( stack, paragraphify, this);

              last_li.push.apply( last_li, this.toTree( contained, [] ) );
            }

            var next_block = next[0] && next[0].valueOf() || "";

            if ( next_block.match(is_list_re) || next_block.match( /^ / ) ) {
              block = next.shift();

              // Check for an HR following a list: features/lists/hr_abutting
              var hr = this.dialect.block.horizRule( this, block, next);

              if ( hr ) {
                ret.push.apply(ret, hr);
                break;
              }

              // Add paragraphs if the indentation level stays the same
              if (stack[stack.length-1].indent === block.match(/^\s*/)[0]) {
                forEach( stack, paragraphify, this);
              }

              loose = true;
              continue loose_search;
            }
            break;
          } // loose_search

          return ret;
        };
      })(),

      blockquote: function blockquote( block, next ) {

        // Handle quotes that have spaces before them
        var m = /(^|\n) +(\>[\s\S]*)/.exec(block);
        if (m && m[2] && m[2].length) {
          var blockContents = block.replace(/(^|\n) +\>/, "$1>");
          next.unshift(blockContents);
          return [];
        }

        if ( !block.match( /^>/m ) )
          return undefined;

        var jsonml = [];

        // separate out the leading abutting block, if any. I.e. in this case:
        //
        //  a
        //  > b
        //
        if ( block[ 0 ] !== ">" ) {
          var lines = block.split( /\n/ ),
              prev = [],
              line_no = block.lineNumber;

          // keep shifting lines until you find a crotchet
          while ( lines.length && lines[ 0 ][ 0 ] !== ">" ) {
            prev.push( lines.shift() );
            line_no++;
          }

          var abutting = mk_block( prev.join( "\n" ), "\n", block.lineNumber );
          jsonml.push.apply( jsonml, this.processBlock( abutting, [] ) );
          // reassemble new block of just block quotes!
          block = mk_block( lines.join( "\n" ), block.trailing, line_no );
        }


        // if the next block is also a blockquote merge it in
        while ( next.length && next[ 0 ][ 0 ] === ">" ) {
          var b = next.shift();
          block = mk_block( block + block.trailing + b, b.trailing, block.lineNumber );
        }

        // Strip off the leading "> " and re-process as a block.
        var input = block.replace( /^> ?/gm, "" ),
            old_tree = this.tree,
            processedBlock = this.toTree( input, [ "blockquote" ] ),
            attr = extract_attr( processedBlock );

        // If any link references were found get rid of them
        if ( attr && attr.references ) {
          delete attr.references;
          // And then remove the attribute object if it's empty
          if ( isEmpty( attr ) )
            processedBlock.splice( 1, 1 );
        }

        jsonml.push( processedBlock );
        return jsonml;
      },

      referenceDefn: function referenceDefn( block, next) {
        var re = /^\s*\[(.*?)\]:\s*(\S+)(?:\s+(?:(['"])(.*)\3|\((.*?)\)))?\n?/;
        // interesting matches are [ , ref_id, url, , title, title ]

        if ( !block.match(re) )
          return undefined;

        var attrs = create_attrs.call( this );

        var b = this.loop_re_over_block(re, block, function( m ) {
          create_reference(attrs, m);
        } );

        if ( b.length )
          next.unshift( mk_block( b, block.trailing ) );

        return [];
      },

      para: function para( block ) {
        // everything's a para!
        return [ ["para"].concat( this.processInline( block ) ) ];
      }
    },

    inline: {

      __oneElement__: function oneElement( text, patterns_or_re, previous_nodes ) {
        var m,
            res;

        patterns_or_re = patterns_or_re || this.dialect.inline.__patterns__;
        var re = new RegExp( "([\\s\\S]*?)(" + (patterns_or_re.source || patterns_or_re) + ")" );

        m = re.exec( text );
        if (!m) {
          // Just boring text
          return [ text.length, text ];
        }
        else if ( m[1] ) {
          // Some un-interesting text matched. Return that first
          return [ m[1].length, m[1] ];
        }

        var res;
        if ( m[2] in this.dialect.inline ) {
          res = this.dialect.inline[ m[2] ].call(
                    this,
                    text.substr( m.index ), m, previous_nodes || [] );
        }
        // Default for now to make dev easier. just slurp special and output it.
        res = res || [ m[2].length, m[2] ];
        return res;
      },

      __call__: function inline( text, patterns ) {

        var out = [],
            res;

        function add(x) {
          //D:self.debug("  adding output", uneval(x));
          if ( typeof x === "string" && typeof out[out.length-1] === "string" )
            out[ out.length-1 ] += x;
          else
            out.push(x);
        }

        while ( text.length > 0 ) {
          res = this.dialect.inline.__oneElement__.call(this, text, patterns, out );
          text = text.substr( res.shift() );
          forEach(res, add );
        }

        return out;
      },

      // These characters are intersting elsewhere, so have rules for them so that
      // chunks of plain text blocks don't include them
      "]": function () {},
      "}": function () {},

      __escape__ : /^\\[\\`\*_{}<>\[\]()#\+.!\-]/,

      "\\": function escaped( text ) {
        // [ length of input processed, node/children to add... ]
        // Only esacape: \ ` * _ { } [ ] ( ) # * + - . !
        if ( this.dialect.inline.__escape__.exec( text ) )
          return [ 2, text.charAt( 1 ) ];
        else
          // Not an esacpe
          return [ 1, "\\" ];
      },

      "![": function image( text ) {

        // Unlike images, alt text is plain text only. no other elements are
        // allowed in there

        // ![Alt text](/path/to/img.jpg "Optional title")
        //      1          2            3       4         <--- captures
        //
        // First attempt to use a strong URL regexp to catch things like parentheses. If it misses, use the
        // old one.
        var m = text.match( /^!\[(.*?)][ \t]*\(((?:https?:(?:\/{1,3}|[a-z0-9%])|www\d{0,3}[.])(?:[^\s()<>]+|\([^\s()<>]+\))+(?:\([^\s()<>]+\)|[^`!()\[\]{};:'".,<>?«»“”‘’\s]))\)([ \t])*(["'].*["'])?/ ) ||
                text.match( /^!\[(.*?)\][ \t]*\([ \t]*([^")]*?)(?:[ \t]+(["'])(.*?)\3)?[ \t]*\)/ );

        if ( m ) {
          if ( m[2] && m[2][0] === "<" && m[2][m[2].length-1] === ">" )
            m[2] = m[2].substring( 1, m[2].length - 1 );

          m[2] = this.dialect.inline.__call__.call( this, m[2], /\\/ )[0];

          var attrs = { alt: m[1], href: m[2] || "" };
          if ( m[4] !== undefined)
            attrs.title = m[4];

          return [ m[0].length, [ "img", attrs ] ];
        }

        // ![Alt text][id]
        m = text.match( /^!\[(.*?)\][ \t]*\[(.*?)\]/ );

        if ( m ) {
          // We can't check if the reference is known here as it likely wont be
          // found till after. Check it in md tree->hmtl tree conversion
          return [ m[0].length, [ "img_ref", { alt: m[1], ref: m[2].toLowerCase(), original: m[0] } ] ];
        }

        // Just consume the '!['
        return [ 2, "![" ];
      },

      "[": function link( text ) {

        var orig = String(text);
        // Inline content is possible inside `link text`
        var res = inline_until_char.call( this, text.substr(1), "]" );

        // No closing ']' found. Just consume the [
        if ( !res )
          return [ 1, "[" ];

        var consumed = 1 + res[ 0 ],
            children = res[ 1 ],
            link,
            attrs;

        // At this point the first [...] has been parsed. See what follows to find
        // out which kind of link we are (reference or direct url)
        text = text.substr( consumed );

        // [link text](/path/to/img.jpg "Optional title")
        //                 1            2       3         <--- captures
        // This will capture up to the last paren in the block. We then pull
        // back based on if there a matching ones in the url
        //    ([here](/url/(test))
        // The parens have to be balanced
        var m = text.match( /^\s*\([ \t]*([^"']*)(?:[ \t]+(["'])(.*?)\2)?[ \t]*\)/ );
        if ( m ) {
          var url = m[1].replace(/\s+$/, '');
          consumed += m[0].length;

          if ( url && url[0] === "<" && url[url.length-1] === ">" )
            url = url.substring( 1, url.length - 1 );

          // If there is a title we don't have to worry about parens in the url
          if ( !m[3] ) {
            var open_parens = 1; // One open that isn't in the capture
            for ( var len = 0; len < url.length; len++ ) {
              switch ( url[len] ) {
              case "(":
                open_parens++;
                break;
              case ")":
                if ( --open_parens === 0) {
                  consumed -= url.length - len;
                  url = url.substring(0, len);
                }
                break;
              }
            }
          }

          // Process escapes only
          url = this.dialect.inline.__call__.call( this, url, /\\/ )[0];

          attrs = { href: url || "" };
          if ( m[3] !== undefined)
            attrs.title = m[3];

          link = [ "link", attrs ].concat( children );
          return [ consumed, link ];
        }

        // [Alt text][id]
        // [Alt text] [id]
        m = text.match( /^\s*\[(.*?)\]/ );

        if ( m ) {

          consumed += m[ 0 ].length;

          // [links][] uses links as its reference
          attrs = { ref: ( m[ 1 ] || String(children) ).toLowerCase(),  original: orig.substr( 0, consumed ) };

          link = [ "link_ref", attrs ].concat( children );

          // We can't check if the reference is known here as it likely wont be
          // found till after. Check it in md tree->hmtl tree conversion.
          // Store the original so that conversion can revert if the ref isn't found.
          return [ consumed, link ];
        }

        // Another check for references
        m = orig.match(/^\s*\[(.*?)\]:\s*(\S+)(?:\s+(?:(['"])(.*?)\3|\((.*?)\)))?\n?/);
        if (m) {
          var attrs = create_attrs.call(this);
          create_reference(attrs, m);
          return [ m[0].length ];
        }

        // [id]
        // Only if id is plain (no formatting.)
        if ( children.length === 1 && typeof children[0] === "string" ) {

          var normalized = children[0].toLowerCase().replace(/\s+/, ' ');
          attrs = { ref: normalized,  original: orig.substr( 0, consumed ) };
          link = [ "link_ref", attrs, children[0] ];
          return [ consumed, link ];
        }

        // Just consume the "["
        return [ 1, "[" ];
      },


      "<": function autoLink( text ) {
        var m;

        if ( ( m = text.match( /^<(?:((https?|ftp|mailto):[^>]+)|(.*?@.*?\.[a-zA-Z]+))>/ ) ) !== null ) {
          if ( m[3] )
            return [ m[0].length, [ "link", { href: "mailto:" + m[3] }, m[3] ] ];
          else if ( m[2] === "mailto" )
            return [ m[0].length, [ "link", { href: m[1] }, m[1].substr("mailto:".length ) ] ];
          else
            return [ m[0].length, [ "link", { href: m[1] }, m[1] ] ];
        }

        return [ 1, "<" ];
      },

      "`": function inlineCode( text ) {
        // Inline code block. as many backticks as you like to start it
        // Always skip over the opening ticks.
        var m = text.match( /(`+)(([\s\S]*?)\1)/ );

        if ( m && m[2] )
          return [ m[1].length + m[2].length, [ "inlinecode", m[3] ] ];
        else {
          // TODO: No matching end code found - warn!
          return [ 1, "`" ];
        }
      },

      "  \n": function lineBreak() {
        return [ 3, [ "linebreak" ] ];
      }

    }
  };

  // Meta Helper/generator method for em and strong handling
  function strong_em( tag, md ) {

    var state_slot = tag + "_state",
        other_slot = tag === "strong" ? "em_state" : "strong_state";

    function CloseTag(len) {
      this.len_after = len;
      this.name = "close_" + md;
    }

    return function ( text ) {

      if ( this[state_slot][0] === md ) {
        // Most recent em is of this type
        //D:this.debug("closing", md);
        this[state_slot].shift();

        // "Consume" everything to go back to the recrusion in the else-block below
        return[ text.length, new CloseTag(text.length-md.length) ];
      }
      else {
        // Store a clone of the em/strong states
        var other = this[other_slot].slice(),
            state = this[state_slot].slice();

        this[state_slot].unshift(md);

        //D:this.debug_indent += "  ";

        // Recurse
        var res = this.processInline( text.substr( md.length ) );
        //D:this.debug_indent = this.debug_indent.substr(2);

        var last = res[res.length - 1];

        //D:this.debug("processInline from", tag + ": ", uneval( res ) );

        var check = this[state_slot].shift();
        if ( last instanceof CloseTag ) {
          res.pop();
          // We matched! Huzzah.
          var consumed = text.length - last.len_after;
          return [ consumed, [ tag ].concat(res) ];
        }
        else {
          // Restore the state of the other kind. We might have mistakenly closed it.
          this[other_slot] = other;
          this[state_slot] = state;

          // We can't reuse the processed result as it could have wrong parsing contexts in it.
          return [ md.length, md ];
        }
      }
    }; // End returned function
  }

  // A helper function to create attributes
  function create_attrs() {
    if ( !extract_attr( this.tree ) ) {
      this.tree.splice( 1, 0, {} );
    }

    var attrs = extract_attr( this.tree );

    // make a references hash if it doesn't exist
    if ( attrs.references === undefined ) {
      attrs.references = {};
    }

    return attrs;
  }

  // Create references for attributes
  function create_reference(attrs, m) {
    if ( m[2] && m[2][0] === "<" && m[2][m[2].length-1] === ">" )
      m[2] = m[2].substring( 1, m[2].length - 1 );

    var ref = attrs.references[ m[1].toLowerCase() ] = {
      href: m[2]
    };

    if ( m[4] !== undefined )
      ref.title = m[4];
    else if ( m[5] !== undefined )
      ref.title = m[5];
  }

  Gruber.inline["**"] = strong_em("strong", "**");
  Gruber.inline["__"] = strong_em("strong", "__");
  Gruber.inline["*"]  = strong_em("em", "*");
  Gruber.inline["_"]  = strong_em("em", "_");

  Markdown.dialects.Gruber = Gruber;
  Markdown.buildBlockOrder ( Markdown.dialects.Gruber.block );
  Markdown.buildInlinePatterns( Markdown.dialects.Gruber.inline );

  return Gruber;
});