text: // Released under MIT license
  // Copyright (c) 2009-2010 Dominic Baggott
  // Copyright (c) 2009-2010 Ash Berlin
  // Copyright (c) 2011 Christoph Dorn <christoph@christophdorn.com> (http://www.christophdorn.com)
  
  (function(expose) {
  
      /**
       *  class Markdown
       *
       *  Markdown processing in Javascript done right. We have very particular views
       *  on what constitutes 'right' which include:
       *
       *  - produces well-formed HTML (this means that em and strong nesting is
       *    important)
       *
       *  - has an intermediate representation to allow processing of parsed data (We
       *    in fact have two, both as [JsonML]: a markdown tree and an HTML tree).
       *
       *  - is easily extensible to add new dialects without having to rewrite the
       *    entire parsing mechanics
       *
       *  - has a good test suite
       *
       *  This implementation fulfills all of these (except that the test suite could
       *  do with expanding to automatically run all the fixtures from other Markdown
       *  implementations.)
       *
       *  ##### Intermediate Representation
       *
       *  *TODO* Talk about this :) Its JsonML, but document the node names we use.
       *
       *  [JsonML]: http://jsonml.org/ "JSON Markup Language"
       **/
      var Markdown = expose.Markdown = function Markdown(dialect) {
          switch (typeof dialect) {
              case "undefined":
                  this.dialect = Markdown.dialects.Gruber;
                  break;
              case "object":
                  this.dialect = dialect;
                  break;
              default:
                  if (dialect in Markdown.dialects) {
                      this.dialect = Markdown.dialects[dialect];
                  }
                  else {
                      throw new Error("Unknown Markdown dialect '" + String(dialect) + "'");
                  }
                  break;
          }
          this.em_state = [];
          this.strong_state = [];
          this.debug_indent = "";
      };
  
      /**
       *  parse( markdown, [dialect] ) -> JsonML
       *  - markdown (String): markdown string to parse
       *  - dialect (String | Dialect): the dialect to use, defaults to gruber
       *
       *  Parse `markdown` and return a markdown document as a Markdown.JsonML tree.
       **/
      expose.parse = function(source, dialect) {
          // dialect will default if undefined
          var md = new Markdown(dialect);
          return md.toTree(source);
      };
  
      /**
       *  toHTML( markdown, [dialect]  ) -> String
       *  toHTML( md_tree ) -> String
       *  - markdown (String): markdown string to parse
       *  - md_tree (Markdown.JsonML): parsed markdown tree
       *
       *  Take markdown (either as a string or as a JsonML tree) and run it through
       *  [[toHTMLTree]] then turn it into a well-formated HTML fragment.
       **/
      expose.toHTML = function toHTML(source, dialect, options) {
          var input = expose.toHTMLTree(source, dialect, options);
  
          return expose.renderJsonML(input);
      };
  
      /**
       *  toHTMLTree( markdown, [dialect] ) -> JsonML
       *  toHTMLTree( md_tree ) -> JsonML
       *  - markdown (String): markdown string to parse
       *  - dialect (String | Dialect): the dialect to use, defaults to gruber
       *  - md_tree (Markdown.JsonML): parsed markdown tree
       *
       *  Turn markdown into HTML, represented as a JsonML tree. If a string is given
       *  to this function, it is first parsed into a markdown tree by calling
       *  [[parse]].
       **/
      expose.toHTMLTree = function toHTMLTree(input, dialect, options) {
          // convert string input to an MD tree
          if (typeof input === "string")
              input = this.parse(input, dialect);
  
          // Now convert the MD tree to an HTML tree
  
          // remove references from the tree
          var attrs = extract_attr(input),
                  refs = {};
  
          if (attrs && attrs.references) {
              refs = attrs.references;
          }
  
          var html = convert_tree_to_html(input, refs, options);
          merge_text_nodes(html);
          return html;
      };
  
  // For Spidermonkey based engines
      function mk_block_toSource() {
          return "Markdown.mk_block( " +
                  uneval(this.toString()) +
                  ", " +
                  uneval(this.trailing) +
                  ", " +
                  uneval(this.lineNumber) +
                  " )";
      }
  
  // node
      function mk_block_inspect() {
          var util = require('util');
          return "Markdown.mk_block( " +
                  util.inspect(this.toString()) +
                  ", " +
                  util.inspect(this.trailing) +
                  ", " +
                  util.inspect(this.lineNumber) +
                  " )";
  
      }
  
      var mk_block = Markdown.mk_block = function(block, trail, line) {
          // Be helpful for default case in tests.
          if (arguments.length == 1)
              trail = "\n\n";
  
          var s = new String(block);
          s.trailing = trail;
          // To make it clear its not just a string
          s.inspect = mk_block_inspect;
          s.toSource = mk_block_toSource;
  
          if (line != undefined)
              s.lineNumber = line;
  
          return s;
      };
  
      function count_lines(str) {
          var n = 0, i = -1;
          while ((i = str.indexOf('\n', i + 1)) !== - 1)
              n++;
          return n;
      }
  
  // Internal - split source into rough blocks
      Markdown.prototype.split_blocks = function splitBlocks(input, startLine) {
          // [\s\S] matches _anything_ (newline or space)
          var re = /([\s\S]+?)($|\n(?:\s*\n|$)+)/g,
                  blocks = [],
                  m;
  
          var line_no = 1;
  
          if ((m = /^(\s*\n)/.exec(input)) != null) {
              // skip (but count) leading blank lines
              line_no += count_lines(m[0]);
              re.lastIndex = m[0].length;
          }
  
          while ((m = re.exec(input)) !== null) {
              blocks.push(mk_block(m[1], m[2], line_no));
              line_no += count_lines(m[0]);
          }
  
          return blocks;
      };
  
      /**
       *  Markdown#processBlock( block, next ) -> undefined | [ JsonML, ... ]
       *  - block (String): the block to process
       *  - next (Array): the following blocks
       *
       * Process `block` and return an array of JsonML nodes representing `block`.
       *
       * It does this by asking each block level function in the dialect to process
       * the block until one can. Succesful handling is indicated by returning an
       * array (with zero or more JsonML nodes), failure by a false value.
       *
       * Blocks handlers are responsible for calling [[Markdown#processInline]]
       * themselves as appropriate.
       *
       * If the blocks were split incorrectly or adjacent blocks need collapsing you
       * can adjust `next` in place using shift/splice etc.
       *
       * If any of this default behaviour is not right for the dialect, you can
       * define a `__call__` method on the dialect that will get invoked to handle
       * the block processing.
       */
      Markdown.prototype.processBlock = function processBlock(block, next) {
          var cbs = this.dialect.block,
                  ord = cbs.__order__;
  
          if ("__call__" in cbs) {
              return cbs.__call__.call(this, block, next);
          }
  
          for (var i = 0; i < ord.length; i++) {
              //D:this.debug( "Testing", ord[i] );
              var res = cbs[ ord[i] ].call(this, block, next);
              if (res) {
                  //D:this.debug("  matched");
                  if (!isArray(res) || (res.length > 0 && !(isArray(res[0]))))
                      this.debug(ord[i], "didn't return a proper array");
                  //D:this.debug( "" );
                  return res;
              }
          }
  
          // Uhoh! no match! Should we throw an error?
          return [];
      };
  
      Markdown.prototype.processInline = function processInline(block) {
          return this.dialect.inline.__call__.call(this, String(block));
      };
  
      /**
       *  Markdown#toTree( source ) -> JsonML
       *  - source (String): markdown source to parse
       *
       *  Parse `source` into a JsonML tree representing the markdown document.
       **/
  // custom_tree means set this.tree to `custom_tree` and restore old value on return
      Markdown.prototype.toTree = function toTree(source, custom_root) {
          var blocks = source instanceof Array ? source : this.split_blocks(source);
  
          // Make tree a member variable so its easier to mess with in extensions
          var old_tree = this.tree;
          try {
              this.tree = custom_root || this.tree || ["markdown"];
  
              blocks:
                      while (blocks.length) {
                  var b = this.processBlock(blocks.shift(), blocks);
  
                  // Reference blocks and the like won't return any content
                  if (!b.length)
                      continue blocks;
  
                  this.tree.push.apply(this.tree, b);
              }
              return this.tree;
          }
          finally {
              if (custom_root) {
                  this.tree = old_tree;
              }
          }
      };
  
  // Noop by default
      Markdown.prototype.debug = function() {
          var args = Array.prototype.slice.call(arguments);
          args.unshift(this.debug_indent);
          if (typeof print !== "undefined")
              print.apply(print, args);
          if (typeof console !== "undefined" && typeof console.log !== "undefined")
              console.log.apply(null, args);
      }
  
      Markdown.prototype.loop_re_over_block = function(re, block, cb) {
          // Dont use /g regexps with this
          var m,
                  b = block.valueOf();
  
          while (b.length && (m = re.exec(b)) != null) {
              b = b.substr(m[0].length);
              cb.call(this, m);
          }
          return b;
      };
  
      /**
       * Markdown.dialects
       *
       * Namespace of built-in dialects.
       **/
      Markdown.dialects = {};
  
      /**
       * Markdown.dialects.Gruber
       *
       * 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.
       **/
      Markdown.dialects.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;
                  var header = ["header", {level: level}, 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?/,
                          lines;
  
                  // 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 ]) {
                      jsonml.unshift.apply(jsonml, this.processBlock(m[ 1 ], []));
                  }
  
                  // if there's a trailing abutting block, stick it into next
                  if (m[ 3 ]) {
                      next.unshift(mk_block(m[ 3 ]));
                  }
  
                  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 = /[*+-]/,
                          number_list = /\d+\./,
                          // 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));
                          }
                          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)));
                      }
                      else {
                          var sublist = last_li.pop();
                          last_li.push(["para"].concat(last_li.splice(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 = "";
  
                          // Loop over the lines in this block looking for tight lists.
                          tight_search:
                                  for (var line_no = 0; line_no < lines.length; line_no++) {
                              var nl = "",
                                      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);
                                          found = true;
                                          break;
                                      }
  
                                      if (!found) {
                                          //print("not found. l:", uneval(l));
                                          wanted_depth++;
                                          if (wanted_depth <= stack.length) {
                                              stack.splice(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);
                              // 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(block, next);
  
                              if (hr) {
                                  ret.push.apply(ret, hr);
                                  break;
                              }
  
                              // Make sure all listitems up the stack are paragraphs
                              forEach(stack, paragraphify, this);
  
                              loose = true;
                              continue loose_search;
                          }
                          break;
                      } // loose_search
  
                      return ret;
                  };
              })(),
              blockquote: function blockquote(block, next) {
                  if (!block.match(/^>/m))
                      return undefined;
  
                  var jsonml = [];
  
                  // separate out the leading abutting block, if any
                  if (block[ 0 ] != ">") {
                      var lines = block.split(/\n/),
                              prev = [];
  
                      // keep shifting lines until you find a crotchet
                      while (lines.length && lines[ 0 ][ 0 ] != ">") {
                          prev.push(lines.shift());
                      }
  
                      // reassemble!
                      block = lines.join("\n");
                      jsonml.push.apply(jsonml, this.processBlock(prev.join("\n"), []));
                  }
  
                  // if the next block is also a blockquote merge it in
                  while (next.length && next[ 0 ][ 0 ] == ">") {
                      var b = next.shift();
                      block = new String(block + block.trailing + b);
                      block.trailing = b.trailing;
                  }
  
                  // Strip off the leading "> " and re-process as a block.
                  var input = block.replace(/^> ?/gm, ''),
                          old_tree = this.tree;
                  jsonml.push(this.toTree(input, ["blockquote"]));
  
                  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;
  
                  // make an attribute node if it doesn't exist
                  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 = {};
                  }
  
                  var b = this.loop_re_over_block(re, block, function(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];
  
                  });
  
                  if (b.length)
                      next.unshift(mk_block(b, block.trailing));
  
                  return [];
              },
              para: function para(block, next) {
                  // everything's a para!
                  return [["para"].concat(this.processInline(block))];
              }
          }
      };
  
      Markdown.dialects.Gruber.inline = {
          __oneElement__: function oneElement(text, patterns_or_re, previous_nodes) {
              var m,
                      res,
                      lastIndex = 0;
  
              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() {
          },
          "\\": function escaped(text) {
              // [ length of input processed, node/children to add... ]
              // Only esacape: \ ` * _ { } [ ] ( ) # * + - . !
              if (text.match(/^\\[\\`\*_{}\[\]()#\+.!\-]/))
                  return [2, text[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
              var m = text.match(/^!\[(.*?)\][ \t]*\([ \t]*(\S*)(?:[ \t]+(["'])(.*?)\3)?[ \t]*\)/);
  
              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 = Markdown.DialectHelpers.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*\([ \t]*(\S+)(?:[ \t]+(["'])(.*?)\2)?[ \t]*\)/);
              if (m) {
                  var url = m[1];
                  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];
              }
  
              // [id]
              // Only if id is plain (no formatting.)
              if (children.length == 1 && typeof children[0] == "string") {
  
                  attrs = {ref: children[0].toLowerCase(), 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(text) {
              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, orig_match) {
  
              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
      }
  
      Markdown.dialects.Gruber.inline["**"] = strong_em("strong", "**");
      Markdown.dialects.Gruber.inline["__"] = strong_em("strong", "__");
      Markdown.dialects.Gruber.inline["*"] = strong_em("em", "*");
      Markdown.dialects.Gruber.inline["_"] = strong_em("em", "_");
  
  
  // Build default order from insertion order.
      Markdown.buildBlockOrder = function(d) {
          var ord = [];
          for (var i in d) {
              if (i == "__order__" || i == "__call__")
                  continue;
              ord.push(i);
          }
          d.__order__ = ord;
      };
  
  // Build patterns for inline matcher
      Markdown.buildInlinePatterns = function(d) {
          var patterns = [];
  
          for (var i in d) {
              // __foo__ is reserved and not a pattern
              if (i.match(/^__.*__$/))
                  continue;
              var l = i.replace(/([\\.*+?|()\[\]{}])/g, "\\$1")
                      .replace(/\n/, "\\n");
              patterns.push(i.length == 1 ? l : "(?:" + l + ")");
          }
  
          patterns = patterns.join("|");
          d.__patterns__ = patterns;
          //print("patterns:", uneval( patterns ) );
  
          var fn = d.__call__;
          d.__call__ = function(text, pattern) {
              if (pattern != undefined) {
                  return fn.call(this, text, pattern);
              }
              else
              {
                  return fn.call(this, text, patterns);
              }
          };
      };
  
      Markdown.DialectHelpers = {};
      Markdown.DialectHelpers.inline_until_char = function(text, want) {
          var consumed = 0,
                  nodes = [];
  
          while (true) {
              if (text[ consumed ] == want) {
                  // Found the character we were looking for
                  consumed++;
                  return [consumed, nodes];
              }
  
              if (consumed >= text.length) {
                  // No closing char found. Abort.
                  return null;
              }
  
              var res = this.dialect.inline.__oneElement__.call(this, text.substr(consumed));
              consumed += res[ 0 ];
              // Add any returned nodes.
              nodes.push.apply(nodes, res.slice(1));
          }
      }
  
  // Helper function to make sub-classing a dialect easier
      Markdown.subclassDialect = function(d) {
          function Block() {
          }
          Block.prototype = d.block;
          function Inline() {
          }
          Inline.prototype = d.inline;
  
          return {block: new Block(), inline: new Inline()};
      };
  
      Markdown.buildBlockOrder(Markdown.dialects.Gruber.block);
      Markdown.buildInlinePatterns(Markdown.dialects.Gruber.inline);
  
      Markdown.dialects.Maruku = Markdown.subclassDialect(Markdown.dialects.Gruber);
  
      Markdown.dialects.Maruku.processMetaHash = function processMetaHash(meta_string) {
          var meta = split_meta_hash(meta_string),
                  attr = {};
  
          for (var i = 0; i < meta.length; ++i) {
              // id: #foo
              if (/^#/.test(meta[ i ])) {
                  attr.id = meta[ i ].substring(1);
              }
              // class: .foo
              else if (/^\./.test(meta[ i ])) {
                  // if class already exists, append the new one
                  if (attr['class']) {
                      attr['class'] = attr['class'] + meta[ i ].replace(/./, " ");
                  }
                  else {
                      attr['class'] = meta[ i ].substring(1);
                  }
              }
              // attribute: foo=bar
              else if (/\=/.test(meta[ i ])) {
                  var s = meta[ i ].split(/\=/);
                  attr[ s[ 0 ] ] = s[ 1 ];
              }
          }
  
          return attr;
      }
  
      function split_meta_hash(meta_string) {
          var meta = meta_string.split(""),
                  parts = [""],
                  in_quotes = false;
  
          while (meta.length) {
              var letter = meta.shift();
              switch (letter) {
                  case " " :
                      // if we're in a quoted section, keep it
                      if (in_quotes) {
                          parts[ parts.length - 1 ] += letter;
                      }
                      // otherwise make a new part
                      else {
                          parts.push("");
                      }
                      break;
                  case "'" :
                  case '"' :
                      // reverse the quotes and move straight on
                      in_quotes = !in_quotes;
                      break;
                  case "\\" :
                      // shift off the next letter to be used straight away.
                      // it was escaped so we'll keep it whatever it is
                      letter = meta.shift();
                  default :
                      parts[ parts.length - 1 ] += letter;
                      break;
              }
          }
  
          return parts;
      }
  
      Markdown.dialects.Maruku.block.document_meta = function document_meta(block, next) {
          // we're only interested in the first block
          if (block.lineNumber > 1)
              return undefined;
  
          // document_meta blocks consist of one or more lines of `Key: Value\n`
          if (!block.match(/^(?:\w+:.*\n)*\w+:.*$/))
              return undefined;
  
          // make an attribute node if it doesn't exist
          if (!extract_attr(this.tree)) {
              this.tree.splice(1, 0, {});
          }
  
          var pairs = block.split(/\n/);
          for (p in pairs) {
              var m = pairs[ p ].match(/(\w+):\s*(.*)$/),
                      key = m[ 1 ].toLowerCase(),
                      value = m[ 2 ];
  
              this.tree[ 1 ][ key ] = value;
          }
  
          // document_meta produces no content!
          return [];
      };
  
      Markdown.dialects.Maruku.block.block_meta = function block_meta(block, next) {
          // check if the last line of the block is an meta hash
          var m = block.match(/(^|\n) {0,3}\{:\s*((?:\\\}|[^\}])*)\s*\}$/);
          if (!m)
              return undefined;
  
          // process the meta hash
          var attr = this.dialect.processMetaHash(m[ 2 ]);
  
          var hash;
  
          // if we matched ^ then we need to apply meta to the previous block
          if (m[ 1 ] === "") {
              var node = this.tree[ this.tree.length - 1 ];
              hash = extract_attr(node);
  
              // if the node is a string (rather than JsonML), bail
              if (typeof node === "string")
                  return undefined;
  
              // create the attribute hash if it doesn't exist
              if (!hash) {
                  hash = {};
                  node.splice(1, 0, hash);
              }
  
              // add the attributes in
              for (a in attr) {
                  hash[ a ] = attr[ a ];
              }
  
              // return nothing so the meta hash is removed
              return [];
          }
  
          // pull the meta hash off the block and process what's left
          var b = block.replace(/\n.*$/, ""),
                  result = this.processBlock(b, []);
  
          // get or make the attributes hash
          hash = extract_attr(result[ 0 ]);
          if (!hash) {
              hash = {};
              result[ 0 ].splice(1, 0, hash);
          }
  
          // attach the attributes to the block
          for (a in attr) {
              hash[ a ] = attr[ a ];
          }
  
          return result;
      };
  
      Markdown.dialects.Maruku.block.definition_list = function definition_list(block, next) {
          // one or more terms followed by one or more definitions, in a single block
          var tight = /^((?:[^\s:].*\n)+):\s+([\s\S]+)$/,
                  list = ["dl"],
                  i;
  
          // see if we're dealing with a tight or loose block
          if ((m = block.match(tight))) {
              // pull subsequent tight DL blocks out of `next`
              var blocks = [block];
              while (next.length && tight.exec(next[ 0 ])) {
                  blocks.push(next.shift());
              }
  
              for (var b = 0; b < blocks.length; ++b) {
                  var m = blocks[ b ].match(tight),
                          terms = m[ 1 ].replace(/\n$/, "").split(/\n/),
                          defns = m[ 2 ].split(/\n:\s+/);
  
                  // print( uneval( m ) );
  
                  for (i = 0; i < terms.length; ++i) {
                      list.push(["dt", terms[ i ]]);
                  }
  
                  for (i = 0; i < defns.length; ++i) {
                      // run inline processing over the definition
                      list.push(["dd"].concat(this.processInline(defns[ i ].replace(/(\n)\s+/, "$1"))));
                  }
              }
          }
          else {
              return undefined;
          }
  
          return [list];
      };
  
      Markdown.dialects.Maruku.inline[ "{:" ] = function inline_meta(text, matches, out) {
          if (!out.length) {
              return [2, "{:"];
          }
  
          // get the preceeding element
          var before = out[ out.length - 1 ];
  
          if (typeof before === "string") {
              return [2, "{:"];
          }
  
          // match a meta hash
          var m = text.match(/^\{:\s*((?:\\\}|[^\}])*)\s*\}/);
  
          // no match, false alarm
          if (!m) {
              return [2, "{:"];
          }
  
          // attach the attributes to the preceeding element
          var meta = this.dialect.processMetaHash(m[ 1 ]),
                  attr = extract_attr(before);
  
          if (!attr) {
              attr = {};
              before.splice(1, 0, attr);
          }
  
          for (var k in meta) {
              attr[ k ] = meta[ k ];
          }
  
          // cut out the string and replace it with nothing
          return [m[ 0 ].length, ""];
      };
  
      Markdown.buildBlockOrder(Markdown.dialects.Maruku.block);
      Markdown.buildInlinePatterns(Markdown.dialects.Maruku.inline);
  
      var isArray = Array.isArray || function(obj) {
          return Object.prototype.toString.call(obj) == '[object Array]';
      };
  
      var forEach;
  // Don't mess with Array.prototype. Its not friendly
      if (Array.prototype.forEach) {
          forEach = function(arr, cb, thisp) {
              return arr.forEach(cb, thisp);
          };
      }
      else {
          forEach = function(arr, cb, thisp) {
              for (var i = 0; i < arr.length; i++) {
                  cb.call(thisp || arr, arr[i], i, arr);
              }
          }
      }
  
      function extract_attr(jsonml) {
          return isArray(jsonml)
                  && jsonml.length > 1
                  && typeof jsonml[ 1 ] === "object"
                  && !(isArray(jsonml[ 1 ]))
                  ? jsonml[ 1 ]
                  : undefined;
      }
  
  
  
      /**
       *  renderJsonML( jsonml[, options] ) -> String
       *  - jsonml (Array): JsonML array to render to XML
       *  - options (Object): options
       *
       *  Converts the given JsonML into well-formed XML.
       *
       *  The options currently understood are:
       *
       *  - root (Boolean): wether or not the root node should be included in the
       *    output, or just its children. The default `false` is to not include the
       *    root itself.
       */
      expose.renderJsonML = function(jsonml, options) {
          options = options || {};
          // include the root element in the rendered output?
          options.root = options.root || false;
  
          var content = [];
  
          if (options.root) {
              content.push(render_tree(jsonml));
          }
          else {
              jsonml.shift(); // get rid of the tag
              if (jsonml.length && typeof jsonml[ 0 ] === "object" && !(jsonml[ 0 ] instanceof Array)) {
                  jsonml.shift(); // get rid of the attributes
              }
  
              while (jsonml.length) {
                  content.push(render_tree(jsonml.shift()));
              }
          }
  
          return content.join("\n\n");
      };
  
      function escapeHTML(text) {
          return text.replace(/&/g, "&amp;")
                  .replace(/</g, "&lt;")
                  .replace(/>/g, "&gt;")
                  .replace(/"/g, "&quot;")
                  .replace(/'/g, "&#39;");
      }
  
      function render_tree(jsonml) {
          // basic case
          if (typeof jsonml === "string") {
              return escapeHTML(jsonml);
          }
  
          var tag = jsonml.shift(),
                  attributes = {},
                  content = [];
  
          if (jsonml.length && typeof jsonml[ 0 ] === "object" && !(jsonml[ 0 ] instanceof Array)) {
              attributes = jsonml.shift();
          }
  
          while (jsonml.length) {
              content.push(arguments.callee(jsonml.shift()));
          }
  
          var tag_attrs = "";
          for (var a in attributes) {
              tag_attrs += " " + a + '="' + escapeHTML(attributes[ a ]) + '"';
          }
  
          // be careful about adding whitespace here for inline elements
          if (tag == "img" || tag == "br" || tag == "hr") {
              return "<" + tag + tag_attrs + "/>";
          }
          else {
              return "<" + tag + tag_attrs + ">" + content.join("") + "</" + tag + ">";
          }
      }
  
      function convert_tree_to_html(tree, references, options) {
          var i;
          options = options || {};
  
          // shallow clone
          var jsonml = tree.slice(0);
  
          if (typeof options.preprocessTreeNode === "function") {
              jsonml = options.preprocessTreeNode(jsonml, references);
          }
  
          // Clone attributes if they exist
          var attrs = extract_attr(jsonml);
          if (attrs) {
              jsonml[ 1 ] = {};
              for (i in attrs) {
                  jsonml[ 1 ][ i ] = attrs[ i ];
              }
              attrs = jsonml[ 1 ];
          }
  
          // basic case
          if (typeof jsonml === "string") {
              return jsonml;
          }
  
          // convert this node
          switch (jsonml[ 0 ]) {
              case "header":
                  jsonml[ 0 ] = "h" + jsonml[ 1 ].level;
                  delete jsonml[ 1 ].level;
                  break;
              case "bulletlist":
                  jsonml[ 0 ] = "ul";
                  break;
              case "numberlist":
                  jsonml[ 0 ] = "ol";
                  break;
              case "listitem":
                  jsonml[ 0 ] = "li";
                  break;
              case "para":
                  jsonml[ 0 ] = "p";
                  break;
              case "markdown":
                  jsonml[ 0 ] = "html";
                  if (attrs)
                      delete attrs.references;
                  break;
              case "code_block":
                  jsonml[ 0 ] = "pre";
                  i = attrs ? 2 : 1;
                  var code = ["code"];
                  code.push.apply(code, jsonml.splice(i));
                  jsonml[ i ] = code;
                  break;
              case "inlinecode":
                  jsonml[ 0 ] = "code";
                  break;
              case "img":
                  jsonml[ 1 ].src = jsonml[ 1 ].href;
                  delete jsonml[ 1 ].href;
                  break;
              case "linebreak":
                  jsonml[ 0 ] = "br";
                  break;
              case "link":
                  jsonml[ 0 ] = "a";
                  break;
              case "link_ref":
                  jsonml[ 0 ] = "a";
  
                  // grab this ref and clean up the attribute node
                  var ref = references[ attrs.ref ];
  
                  // if the reference exists, make the link
                  if (ref) {
                      delete attrs.ref;
  
                      // add in the href and title, if present
                      attrs.href = ref.href;
                      if (ref.title) {
                          attrs.title = ref.title;
                      }
  
                      // get rid of the unneeded original text
                      delete attrs.original;
                  }
                  // the reference doesn't exist, so revert to plain text
                  else {
                      return attrs.original;
                  }
                  break;
              case "img_ref":
                  jsonml[ 0 ] = "img";
  
                  // grab this ref and clean up the attribute node
                  var ref = references[ attrs.ref ];
  
                  // if the reference exists, make the link
                  if (ref) {
                      delete attrs.ref;
  
                      // add in the href and title, if present
                      attrs.src = ref.href;
                      if (ref.title) {
                          attrs.title = ref.title;
                      }
  
                      // get rid of the unneeded original text
                      delete attrs.original;
                  }
                  // the reference doesn't exist, so revert to plain text
                  else {
                      return attrs.original;
                  }
                  break;
          }
  
          // convert all the children
          i = 1;
  
          // deal with the attribute node, if it exists
          if (attrs) {
              // if there are keys, skip over it
              for (var key in jsonml[ 1 ]) {
                  i = 2;
              }
              // if there aren't, remove it
              if (i === 1) {
                  jsonml.splice(i, 1);
              }
          }
  
          for (; i < jsonml.length; ++i) {
              jsonml[ i ] = arguments.callee(jsonml[ i ], references, options);
          }
  
          return jsonml;
      }
  
  
  // merges adjacent text nodes into a single node
      function merge_text_nodes(jsonml) {
          // skip the tag name and attribute hash
          var i = extract_attr(jsonml) ? 2 : 1;
  
          while (i < jsonml.length) {
              // if it's a string check the next item too
              if (typeof jsonml[ i ] === "string") {
                  if (i + 1 < jsonml.length && typeof jsonml[ i + 1 ] === "string") {
                      // merge the second string into the first and remove it
                      jsonml[ i ] += jsonml.splice(i + 1, 1)[ 0 ];
                  }
                  else {
                      ++i;
                  }
              }
              // if it's not a string recurse
              else {
                  arguments.callee(jsonml[ i ]);
                  ++i;
              }
          }
      }
  
  })((function() {
      if (typeof exports === "undefined") {
          window.markdown = {};
          return window.markdown;
      }
      else {
          return exports;
      }
  })());