mikuli.cz

markdown.php (119729B)

---

 <?php
 // Markdown extension, https://github.com/annaesvensson/yellow-markdown
 
 class YellowMarkdown {
     const VERSION = "0.9.8";
     public $yellow;         // access to API
     
     // Handle initialisation
     public function onLoad($yellow) {
         $this->yellow = $yellow;
     }
     
     // Handle page content in raw format
     public function onParseContentRaw($page, $text) {
         $markdown = new YellowMarkdownParser($this->yellow, $page);
         $text = $markdown->transform($text);
         $text = $this->yellow->lookup->normaliseData($text, "html");
         return $text;
     }
 }
 
 // PHP Markdown Lib
 // Copyright (c) 2004-2021 Michel Fortin
 // <https://michelf.ca/>
 // All rights reserved.
 //
 // Original Markdown
 // Copyright (c) 2004-2006 John Gruber
 // <https://daringfireball.net/>
 // All rights reserved.
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 // * Redistributions of source code must retain the above copyright notice,
 //   this list of conditions and the following disclaimer.
 //
 // * Redistributions in binary form must reproduce the above copyright
 //   notice, this list of conditions and the following disclaimer in the
 //   documentation and/or other materials provided with the distribution.
 //
 // * Neither the name "Markdown" nor the names of its contributors may
 //   be used to endorse or promote products derived from this software
 //   without specific prior written permission.
 //
 // This software is provided by the copyright holders and contributors "as
 // is" and any express or implied warranties, including, but not limited
 // to, the implied warranties of merchantability and fitness for a
 // particular purpose are disclaimed. In no event shall the copyright owner
 // or contributors be liable for any direct, indirect, incidental, special,
 // exemplary, or consequential damages (including, but not limited to,
 // procurement of substitute goods or services; loss of use, data, or
 // profits; or business interruption) however caused and on any theory of
 // liability, whether in contract, strict liability, or tort (including
 // negligence or otherwise) arising in any way out of the use of this
 // software, even if advised of the possibility of such damage.
 
 class MarkdownParser {
 	/**
 	 * Define the package version
 	 * @var string
 	 */
 	const MARKDOWNLIB_VERSION = "1.9.1";
 
 	/**
 	 * Simple function interface - Initialize the parser and return the result
 	 * of its transform method. This will work fine for derived classes too.
 	 *
 	 * @api
 	 *
 	 * @param  string $text
 	 * @return string
 	 */
 	public static function defaultTransform($text) {
 		// Take parser class on which this function was called.
 		$parser_class = \get_called_class();
 
 		// Try to take parser from the static parser list
 		static $parser_list;
 		$parser =& $parser_list[$parser_class];
 
 		// Create the parser it not already set
 		if (!$parser) {
 			$parser = new $parser_class;
 		}
 
 		// Transform text using parser.
 		return $parser->transform($text);
 	}
 
 	/**
 	 * Configuration variables
 	 */
 
 	/**
 	 * Change to ">" for HTML output.
 	 * @var string
 	 */
 	public $empty_element_suffix = " />";
 
 	/**
 	 * The width of indentation of the output markup
 	 * @var int
 	 */
 	public $tab_width = 4;
 
 	/**
 	 * Change to `true` to disallow markup or entities.
 	 * @var boolean
 	 */
 	public $no_markup   = false;
 	public $no_entities = false;
 
 
 	/**
 	 * Change to `true` to enable line breaks on \n without two trailling spaces
 	 * @var boolean
 	 */
 	public $hard_wrap = false;
 
 	/**
 	 * Predefined URLs and titles for reference links and images.
 	 * @var array
 	 */
 	public $predef_urls   = array();
 	public $predef_titles = array();
 
 	/**
 	 * Optional filter function for URLs
 	 * @var callable|null
 	 */
 	public $url_filter_func = null;
 
 	/**
 	 * Optional header id="" generation callback function.
 	 * @var callable|null
 	 */
 	public $header_id_func = null;
 
 	/**
 	 * Optional function for converting code block content to HTML
 	 * @var callable|null
 	 */
 	public $code_block_content_func = null;
 
 	/**
 	 * Optional function for converting code span content to HTML.
 	 * @var callable|null
 	 */
 	public $code_span_content_func = null;
 
 	/**
 	 * Class attribute to toggle "enhanced ordered list" behaviour
 	 * setting this to true will allow ordered lists to start from the index
 	 * number that is defined first.
 	 *
 	 * For example:
 	 * 2. List item two
 	 * 3. List item three
 	 *
 	 * Becomes:
 	 * <ol start="2">
 	 * <li>List item two</li>
 	 * <li>List item three</li>
 	 * </ol>
 	 *
 	 * @var bool
 	 */
 	public $enhanced_ordered_list = false;
 
 	/**
 	 * Parser implementation
 	 */
 
 	/**
 	 * Regex to match balanced [brackets].
 	 * Needed to insert a maximum bracked depth while converting to PHP.
 	 * @var int
 	 */
 	protected $nested_brackets_depth = 6;
 	protected $nested_brackets_re;
 
 	protected $nested_url_parenthesis_depth = 4;
 	protected $nested_url_parenthesis_re;
 
 	/**
 	 * Table of hash values for escaped characters:
 	 * @var string
 	 */
 	protected $escape_chars = '\`*_{}[]()>#+-.!';
 	protected $escape_chars_re;
 
 	/**
 	 * Constructor function. Initialize appropriate member variables.
 	 * @return void
 	 */
 	public function __construct() {
 		$this->_initDetab();
 		$this->prepareItalicsAndBold();
 
 		$this->nested_brackets_re =
 			str_repeat('(?>[^\[\]]+|\[', $this->nested_brackets_depth).
 			str_repeat('\])*', $this->nested_brackets_depth);
 
 		$this->nested_url_parenthesis_re =
 			str_repeat('(?>[^()\s]+|\(', $this->nested_url_parenthesis_depth).
 			str_repeat('(?>\)))*', $this->nested_url_parenthesis_depth);
 
 		$this->escape_chars_re = '['.preg_quote($this->escape_chars).']';
 
 		// Sort document, block, and span gamut in ascendent priority order.
 		asort($this->document_gamut);
 		asort($this->block_gamut);
 		asort($this->span_gamut);
 	}
 
 
 	/**
 	 * Internal hashes used during transformation.
 	 * @var array
 	 */
 	protected $urls        = array();
 	protected $titles      = array();
 	protected $html_hashes = array();
 
 	/**
 	 * Status flag to avoid invalid nesting.
 	 * @var boolean
 	 */
 	protected $in_anchor = false;
 
 	/**
 	 * Status flag to avoid invalid nesting.
 	 * @var boolean
 	 */
 	protected $in_emphasis_processing = false;
 
 	/**
 	 * Called before the transformation process starts to setup parser states.
 	 * @return void
 	 */
 	protected function setup() {
 		// Clear global hashes.
 		$this->urls        = $this->predef_urls;
 		$this->titles      = $this->predef_titles;
 		$this->html_hashes = array();
 		$this->in_anchor   = false;
 		$this->in_emphasis_processing = false;
 	}
 
 	/**
 	 * Called after the transformation process to clear any variable which may
 	 * be taking up memory unnecessarly.
 	 * @return void
 	 */
 	protected function teardown() {
 		$this->urls        = array();
 		$this->titles      = array();
 		$this->html_hashes = array();
 	}
 
 	/**
 	 * Main function. Performs some preprocessing on the input text and pass
 	 * it through the document gamut.
 	 *
 	 * @api
 	 *
 	 * @param  string $text
 	 * @return string
 	 */
 	public function transform($text) {
 		$this->setup();
 
 		# Remove UTF-8 BOM and marker character in input, if present.
 		$text = preg_replace('{^\xEF\xBB\xBF|\x1A}', '', $text);
 
 		# Standardize line endings:
 		#   DOS to Unix and Mac to Unix
 		$text = preg_replace('{\r\n?}', "\n", $text);
 
 		# Make sure $text ends with a couple of newlines:
 		$text .= "\n\n";
 
 		# Convert all tabs to spaces.
 		$text = $this->detab($text);
 
 		# Turn block-level HTML blocks into hash entries
 		$text = $this->hashHTMLBlocks($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 /[ ]*\n+/ .
 		$text = preg_replace('/^[ ]+$/m', '', $text);
 
 		# Run document gamut methods.
 		foreach ($this->document_gamut as $method => $priority) {
 			$text = $this->$method($text);
 		}
 
 		$this->teardown();
 
 		return $text . "\n";
 	}
 
 	/**
 	 * Define the document gamut
 	 * @var array
 	 */
 	protected $document_gamut = array(
 		// Strip link definitions, store in hashes.
 		"stripLinkDefinitions" => 20,
 		"runBasicBlockGamut"   => 30,
 	);
 
 	/**
 	 * Strips link definitions from text, stores the URLs and titles in
 	 * hash references
 	 * @param  string $text
 	 * @return string
 	 */
 	protected function stripLinkDefinitions($text) {
 
 		$less_than_tab = $this->tab_width - 1;
 
 		// Link defs are in the form: ^[id]: url "optional title"
 		$text = preg_replace_callback('{
 							^[ ]{0,'.$less_than_tab.'}\[(.+)\][ ]?:	# id = $1
 							  [ ]*
 							  \n?				# maybe *one* newline
 							  [ ]*
 							(?:
 							  <(.+?)>			# url = $2
 							|
 							  (\S+?)			# url = $3
 							)
 							  [ ]*
 							  \n?				# maybe one newline
 							  [ ]*
 							(?:
 								(?<=\s)			# lookbehind for whitespace
 								["(]
 								(.*?)			# title = $4
 								[")]
 								[ ]*
 							)?	# title is optional
 							(?:\n+|\Z)
 			}xm',
 			array($this, '_stripLinkDefinitions_callback'),
 			$text
 		);
 		return $text;
 	}
 
 	/**
 	 * The callback to strip link definitions
 	 * @param  array $matches
 	 * @return string
 	 */
 	protected function _stripLinkDefinitions_callback($matches) {
 		$link_id = strtolower($matches[1]);
 		$url = $matches[2] == '' ? $matches[3] : $matches[2];
 		$this->urls[$link_id] = $url;
 		$this->titles[$link_id] =& $matches[4];
 		return ''; // String that will replace the block
 	}
 
 	/**
 	 * Hashify HTML blocks
 	 * @param  string $text
 	 * @return string
 	 */
 	protected function hashHTMLBlocks($text) {
 		if ($this->no_markup) {
 			return $text;
 		}
 
 		$less_than_tab = $this->tab_width - 1;
 
 		/**
 		 * 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:
 		 *
 		 * *  List "a" is made of tags which can be both inline or block-level.
 		 *    These will be treated block-level when the start tag is alone on
 		 *    its line, otherwise they're not matched here and will be taken as
 		 *    inline later.
 		 * *  List "b" is made of tags which are always block-level;
 		 */
 		$block_tags_a_re = 'ins|del';
 		$block_tags_b_re = 'p|div|h[1-6]|blockquote|pre|table|dl|ol|ul|address|'.
 						   'script|noscript|style|form|fieldset|iframe|math|svg|'.
 						   'article|section|nav|aside|hgroup|header|footer|'.
 						   'figure|details|summary';
 
 		// Regular expression for the content of a block tag.
 		$nested_tags_level = 4;
 		$attr = '
 			(?>				# optional tag attributes
 			  \s			# starts with whitespace
 			  (?>
 				[^>"/]+		# text outside quotes
 			  |
 				/+(?!>)		# slash not followed by ">"
 			  |
 				"[^"]*"		# text inside double quotes (tolerate ">")
 			  |
 				\'[^\']*\'	# text inside single quotes (tolerate ">")
 			  )*
 			)?
 			';
 		$content =
 			str_repeat('
 				(?>
 				  [^<]+			# content without tag
 				|
 				  <\2			# nested opening tag
 					'.$attr.'	# attributes
 					(?>
 					  />
 					|
 					  >', $nested_tags_level).	// end of opening tag
 					  '.*?'.					// last level nested tag content
 			str_repeat('
 					  </\2\s*>	# closing nested tag
 					)
 				  |
 					<(?!/\2\s*>	# other tags with a different name
 				  )
 				)*',
 				$nested_tags_level);
 		$content2 = str_replace('\2', '\3', $content);
 
 		/**
 		 * 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>`.
 		 */
 		$text = preg_replace_callback('{(?>
 			(?>
 				(?<=\n)			# Starting on its own line
 				|				# or
 				\A\n?			# the at beginning of the doc
 			)
 			(						# save in $1
 
 			  # Match from `\n<tag>` to `</tag>\n`, handling nested tags
 			  # in between.
 
 						[ ]{0,'.$less_than_tab.'}
 						<('.$block_tags_b_re.')# start tag = $2
 						'.$attr.'>			# attributes followed by > and \n
 						'.$content.'		# content, support nesting
 						</\2>				# the matching end tag
 						[ ]*				# trailing spaces/tabs
 						(?=\n+|\Z)	# followed by a newline or end of document
 
 			| # Special version for tags of group a.
 
 						[ ]{0,'.$less_than_tab.'}
 						<('.$block_tags_a_re.')# start tag = $3
 						'.$attr.'>[ ]*\n	# attributes followed by >
 						'.$content2.'		# content, support nesting
 						</\3>				# the matching end tag
 						[ ]*				# trailing spaces/tabs
 						(?=\n+|\Z)	# followed by a newline or end of document
 
 			| # Special case just for <hr />. It was easier to make a special
 			  # case than to make the other regex more complicated.
 
 						[ ]{0,'.$less_than_tab.'}
 						<(hr)				# start tag = $2
 						'.$attr.'			# attributes
 						/?>					# the matching end tag
 						[ ]*
 						(?=\n{2,}|\Z)		# followed by a blank line or end of document
 
 			| # Special case for standalone HTML comments:
 
 					[ ]{0,'.$less_than_tab.'}
 					(?s:
 						<!-- .*? -->
 					)
 					[ ]*
 					(?=\n{2,}|\Z)		# followed by a blank line or end of document
 
 			| # PHP and ASP-style processor instructions (<? and <%)
 
 					[ ]{0,'.$less_than_tab.'}
 					(?s:
 						<([?%])			# $2
 						.*?
 						\2>
 					)
 					[ ]*
 					(?=\n{2,}|\Z)		# followed by a blank line or end of document
 
 			)
 			)}Sxmi',
 			array($this, '_hashHTMLBlocks_callback'),
 			$text
 		);
 
 		return $text;
 	}
 
 	/**
 	 * The callback for hashing HTML blocks
 	 * @param  string $matches
 	 * @return string
 	 */
 	protected function _hashHTMLBlocks_callback($matches) {
 		$text = $matches[1];
 		$key  = $this->hashBlock($text);
 		return "\n\n$key\n\n";
 	}
 
 	/**
 	 * Called whenever a tag must be hashed when a function insert an atomic
 	 * element in the text stream. Passing $text to through this function gives
 	 * a unique text-token which will be reverted back when calling unhash.
 	 *
 	 * The $boundary argument specify what character should be used to surround
 	 * the token. By convension, "B" is used for block elements that needs not
 	 * to be wrapped into paragraph tags at the end, ":" is used for elements
 	 * that are word separators and "X" is used in the general case.
 	 *
 	 * @param  string $text
 	 * @param  string $boundary
 	 * @return string
 	 */
 	protected function hashPart($text, $boundary = 'X') {
 		// Swap back any tag hash found in $text so we do not have to `unhash`
 		// multiple times at the end.
 		$text = $this->unhash($text);
 
 		// Then hash the block.
 		static $i = 0;
 		$key = "$boundary\x1A" . ++$i . $boundary;
 		$this->html_hashes[$key] = $text;
 		return $key; // String that will replace the tag.
 	}
 
 	/**
 	 * Shortcut function for hashPart with block-level boundaries.
 	 * @param  string $text
 	 * @return string
 	 */
 	protected function hashBlock($text) {
 		return $this->hashPart($text, 'B');
 	}
 
 	/**
 	 * Define the block gamut - these are all the transformations that form
 	 * block-level tags like paragraphs, headers, and list items.
 	 * @var array
 	 */
 	protected $block_gamut = array(
 		"doHeaders"         => 10,
 		"doHorizontalRules" => 20,
 		"doLists"           => 40,
 		"doCodeBlocks"      => 50,
 		"doBlockQuotes"     => 60,
 	);
 
 	/**
 	 * Run block gamut tranformations.
 	 *
 	 * We need to escape raw HTML in Markdown source before doing anything
 	 * else. This need to be done for each block, and not only at the
 	 * begining in the Markdown function since hashed blocks can be part of
 	 * list items and could have been indented. Indented blocks would have
 	 * been seen as a code block in a previous pass of hashHTMLBlocks.
 	 *
 	 * @param  string $text
 	 * @return string
 	 */
 	protected function runBlockGamut($text) {
 		$text = $this->hashHTMLBlocks($text);
 		return $this->runBasicBlockGamut($text);
 	}
 
 	/**
 	 * Run block gamut tranformations, without hashing HTML blocks. This is
 	 * useful when HTML blocks are known to be already hashed, like in the first
 	 * whole-document pass.
 	 *
 	 * @param  string $text
 	 * @return string
 	 */
 	protected function runBasicBlockGamut($text) {
 
 		foreach ($this->block_gamut as $method => $priority) {
 			$text = $this->$method($text);
 		}
 
 		// Finally form paragraph and restore hashed blocks.
 		$text = $this->formParagraphs($text);
 
 		return $text;
 	}
 
 	/**
 	 * Convert horizontal rules
 	 * @param  string $text
 	 * @return string
 	 */
 	protected function doHorizontalRules($text) {
 		return preg_replace(
 			'{
 				^[ ]{0,3}	# Leading space
 				([-*_])		# $1: First marker
 				(?>			# Repeated marker group
 					[ ]{0,2}	# Zero, one, or two spaces.
 					\1			# Marker character
 				){2,}		# Group repeated at least twice
 				[ ]*		# Tailing spaces
 				$			# End of line.
 			}mx',
 			"\n".$this->hashBlock("<hr$this->empty_element_suffix")."\n",
 			$text
 		);
 	}
 
 	/**
 	 * These are all the transformations that occur *within* block-level
 	 * tags like paragraphs, headers, and list items.
 	 * @var array
 	 */
 	protected $span_gamut = array(
 		// Process character escapes, code spans, and inline HTML
 		// in one shot.
 		"parseSpan"           => -30,
 		// Process anchor and image tags. Images must come first,
 		// because ![foo][f] looks like an anchor.
 		"doImages"            =>  10,
 		"doAnchors"           =>  20,
 		// Make links out of things like `<https://example.com/>`
 		// Must come after doAnchors, because you can use < and >
 		// delimiters in inline links like [this](<url>).
 		"doAutoLinks"         =>  30,
 		"encodeAmpsAndAngles" =>  40,
 		"doItalicsAndBold"    =>  50,
 		"doHardBreaks"        =>  60,
 	);
 
 	/**
 	 * Run span gamut transformations
 	 * @param  string $text
 	 * @return string
 	 */
 	protected function runSpanGamut($text) {
 		foreach ($this->span_gamut as $method => $priority) {
 			$text = $this->$method($text);
 		}
 
 		return $text;
 	}
 
 	/**
 	 * Do hard breaks
 	 * @param  string $text
 	 * @return string
 	 */
 	protected function doHardBreaks($text) {
 		if ($this->hard_wrap) {
 			return preg_replace_callback('/ *\n/',
 				array($this, '_doHardBreaks_callback'), $text);
 		} else {
 			return preg_replace_callback('/ {2,}\n/',
 				array($this, '_doHardBreaks_callback'), $text);
 		}
 	}
 
 	/**
 	 * Trigger part hashing for the hard break (callback method)
 	 * @param  array $matches
 	 * @return string
 	 */
 	protected function _doHardBreaks_callback($matches) {
 		return $this->hashPart("<br$this->empty_element_suffix\n");
 	}
 
 	/**
 	 * Turn Markdown link shortcuts into XHTML <a> tags.
 	 * @param  string $text
 	 * @return string
 	 */
 	protected function doAnchors($text) {
 		if ($this->in_anchor) {
 			return $text;
 		}
 		$this->in_anchor = true;
 
 		// First, handle reference-style links: [link text] [id]
 		$text = preg_replace_callback('{
 			(					# wrap whole match in $1
 			  \[
 				('.$this->nested_brackets_re.')	# link text = $2
 			  \]
 
 			  [ ]?				# one optional space
 			  (?:\n[ ]*)?		# one optional newline followed by spaces
 
 			  \[
 				(.*?)		# id = $3
 			  \]
 			)
 			}xs',
 			array($this, '_doAnchors_reference_callback'), $text);
 
 		// Next, inline-style links: [link text](url "optional title")
 		$text = preg_replace_callback('{
 			(				# wrap whole match in $1
 			  \[
 				('.$this->nested_brackets_re.')	# link text = $2
 			  \]
 			  \(			# literal paren
 				[ \n]*
 				(?:
 					<(.+?)>	# href = $3
 				|
 					('.$this->nested_url_parenthesis_re.')	# href = $4
 				)
 				[ \n]*
 				(			# $5
 				  ([\'"])	# quote char = $6
 				  (.*?)		# Title = $7
 				  \6		# matching quote
 				  [ \n]*	# ignore any spaces/tabs between closing quote and )
 				)?			# title is optional
 			  \)
 			)
 			}xs',
 			array($this, '_doAnchors_inline_callback'), $text);
 
 		// Last, handle reference-style shortcuts: [link text]
 		// These must come last in case you've also got [link text][1]
 		// or [link text](/foo)
 		$text = preg_replace_callback('{
 			(					# wrap whole match in $1
 			  \[
 				([^\[\]]+)		# link text = $2; can\'t contain [ or ]
 			  \]
 			)
 			}xs',
 			array($this, '_doAnchors_reference_callback'), $text);
 
 		$this->in_anchor = false;
 		return $text;
 	}
 
 	/**
 	 * Callback method to parse referenced anchors
 	 * @param  string $matches
 	 * @return string
 	 */
 	protected function _doAnchors_reference_callback($matches) {
 		$whole_match =  $matches[1];
 		$link_text   =  $matches[2];
 		$link_id     =& $matches[3];
 
 		if ($link_id == "") {
 			// for shortcut links like [this][] or [this].
 			$link_id = $link_text;
 		}
 
 		// lower-case and turn embedded newlines into spaces
 		$link_id = strtolower($link_id);
 		$link_id = preg_replace('{[ ]?\n}', ' ', $link_id);
 
 		if (isset($this->urls[$link_id])) {
 			$url = $this->urls[$link_id];
 			$url = $this->encodeURLAttribute($url);
 
 			$result = "<a href=\"$url\"";
 			if ( isset( $this->titles[$link_id] ) ) {
 				$title = $this->titles[$link_id];
 				$title = $this->encodeAttribute($title);
 				$result .=  " title=\"$title\"";
 			}
 
 			$link_text = $this->runSpanGamut($link_text);
 			$result .= ">$link_text</a>";
 			$result = $this->hashPart($result);
 		} else {
 			$result = $whole_match;
 		}
 		return $result;
 	}
 
 	/**
 	 * Callback method to parse inline anchors
 	 * @param  string $matches
 	 * @return string
 	 */
 	protected function _doAnchors_inline_callback($matches) {
 		$link_text		=  $this->runSpanGamut($matches[2]);
 		$url			=  $matches[3] === '' ? $matches[4] : $matches[3];
 		$title			=& $matches[7];
 
 		// If the URL was of the form <s p a c e s> it got caught by the HTML
 		// tag parser and hashed. Need to reverse the process before using
 		// the URL.
 		$unhashed = $this->unhash($url);
 		if ($unhashed !== $url)
 			$url = preg_replace('/^<(.*)>$/', '\1', $unhashed);
 
 		$url = $this->encodeURLAttribute($url);
 
 		$result = "<a href=\"$url\"";
 		if (isset($title)) {
 			$title = $this->encodeAttribute($title);
 			$result .=  " title=\"$title\"";
 		}
 
 		$link_text = $this->runSpanGamut($link_text);
 		$result .= ">$link_text</a>";
 
 		return $this->hashPart($result);
 	}
 
 	/**
 	 * Turn Markdown image shortcuts into <img> tags.
 	 * @param  string $text
 	 * @return string
 	 */
 	protected function doImages($text) {
 		// First, handle reference-style labeled images: ![alt text][id]
 		$text = preg_replace_callback('{
 			(				# wrap whole match in $1
 			  !\[
 				('.$this->nested_brackets_re.')		# alt text = $2
 			  \]
 
 			  [ ]?				# one optional space
 			  (?:\n[ ]*)?		# one optional newline followed by spaces
 
 			  \[
 				(.*?)		# id = $3
 			  \]
 
 			)
 			}xs',
 			array($this, '_doImages_reference_callback'), $text);
 
 		// Next, handle inline images:  ![alt text](url "optional title")
 		// Don't forget: encode * and _
 		$text = preg_replace_callback('{
 			(				# wrap whole match in $1
 			  !\[
 				('.$this->nested_brackets_re.')		# alt text = $2
 			  \]
 			  \s?			# One optional whitespace character
 			  \(			# literal paren
 				[ \n]*
 				(?:
 					<(\S*)>	# src url = $3
 				|
 					('.$this->nested_url_parenthesis_re.')	# src url = $4
 				)
 				[ \n]*
 				(			# $5
 				  ([\'"])	# quote char = $6
 				  (.*?)		# title = $7
 				  \6		# matching quote
 				  [ \n]*
 				)?			# title is optional
 			  \)
 			)
 			}xs',
 			array($this, '_doImages_inline_callback'), $text);
 
 		return $text;
 	}
 
 	/**
 	 * Callback to parse references image tags
 	 * @param  array $matches
 	 * @return string
 	 */
 	protected function _doImages_reference_callback($matches) {
 		$whole_match = $matches[1];
 		$alt_text    = $matches[2];
 		$link_id     = strtolower($matches[3]);
 
 		if ($link_id == "") {
 			$link_id = strtolower($alt_text); // for shortcut links like ![this][].
 		}
 
 		$alt_text = $this->encodeAttribute($alt_text);
 		if (isset($this->urls[$link_id])) {
 			$url = $this->encodeURLAttribute($this->urls[$link_id]);
 			$result = "<img src=\"$url\" alt=\"$alt_text\"";
 			if (isset($this->titles[$link_id])) {
 				$title = $this->titles[$link_id];
 				$title = $this->encodeAttribute($title);
 				$result .=  " title=\"$title\"";
 			}
 			$result .= $this->empty_element_suffix;
 			$result = $this->hashPart($result);
 		} else {
 			// If there's no such link ID, leave intact:
 			$result = $whole_match;
 		}
 
 		return $result;
 	}
 
 	/**
 	 * Callback to parse inline image tags
 	 * @param  array $matches
 	 * @return string
 	 */
 	protected function _doImages_inline_callback($matches) {
 		$whole_match	= $matches[1];
 		$alt_text		= $matches[2];
 		$url			= $matches[3] == '' ? $matches[4] : $matches[3];
 		$title			=& $matches[7];
 
 		$alt_text = $this->encodeAttribute($alt_text);
 		$url = $this->encodeURLAttribute($url);
 		$result = "<img src=\"$url\" alt=\"$alt_text\"";
 		if (isset($title)) {
 			$title = $this->encodeAttribute($title);
 			$result .=  " title=\"$title\""; // $title already quoted
 		}
 		$result .= $this->empty_element_suffix;
 
 		return $this->hashPart($result);
 	}
 
 	/**
 	 * Parse Markdown heading elements to HTML
 	 * @param  string $text
 	 * @return string
 	 */
 	protected function doHeaders($text) {
 		/**
 		 * Setext-style headers:
 		 *	  Header 1
 		 *	  ========
 		 *
 		 *	  Header 2
 		 *	  --------
 		 */
 		$text = preg_replace_callback('{ ^(.+?)[ ]*\n(=+|-+)[ ]*\n+ }mx',
 			array($this, '_doHeaders_callback_setext'), $text);
 
 		/**
 		 * atx-style headers:
 		 *   # Header 1
 		 *   ## Header 2
 		 *   ## Header 2 with closing hashes ##
 		 *   ...
 		 *   ###### Header 6
 		 */
 		$text = preg_replace_callback('{
 				^(\#{1,6})	# $1 = string of #\'s
 				[ ]*
 				(.+?)		# $2 = Header text
 				[ ]*
 				\#*			# optional closing #\'s (not counted)
 				\n+
 			}xm',
 			array($this, '_doHeaders_callback_atx'), $text);
 
 		return $text;
 	}
 
 	/**
 	 * Setext header parsing callback
 	 * @param  array $matches
 	 * @return string
 	 */
 	protected function _doHeaders_callback_setext($matches) {
 		// Terrible hack to check we haven't found an empty list item.
 		if ($matches[2] == '-' && preg_match('{^-(?: |$)}', $matches[1])) {
 			return $matches[0];
 		}
 
 		$level = $matches[2][0] == '=' ? 1 : 2;
 
 		// ID attribute generation
 		$idAtt = $this->_generateIdFromHeaderValue($matches[1]);
 
 		$block = "<h$level$idAtt>".$this->runSpanGamut($matches[1])."</h$level>";
 		return "\n" . $this->hashBlock($block) . "\n\n";
 	}
 
 	/**
 	 * ATX header parsing callback
 	 * @param  array $matches
 	 * @return string
 	 */
 	protected function _doHeaders_callback_atx($matches) {
 		// ID attribute generation
 		$idAtt = $this->_generateIdFromHeaderValue($matches[2]);
 
 		$level = strlen($matches[1]);
 		$block = "<h$level$idAtt>".$this->runSpanGamut($matches[2])."</h$level>";
 		return "\n" . $this->hashBlock($block) . "\n\n";
 	}
 
 	/**
 	 * If a header_id_func property is set, we can use it to automatically
 	 * generate an id attribute.
 	 *
 	 * This method returns a string in the form id="foo", or an empty string
 	 * otherwise.
 	 * @param  string $headerValue
 	 * @return string
 	 */
 	protected function _generateIdFromHeaderValue($headerValue) {
 		if (!is_callable($this->header_id_func)) {
 			return "";
 		}
 
 		$idValue = call_user_func($this->header_id_func, $headerValue);
 		if (!$idValue) {
 			return "";
 		}
 
 		return ' id="' . $this->encodeAttribute($idValue) . '"';
 	}
 
 	/**
 	 * Form HTML ordered (numbered) and unordered (bulleted) lists.
 	 * @param  string $text
 	 * @return string
 	 */
 	protected function doLists($text) {
 		$less_than_tab = $this->tab_width - 1;
 
 		// Re-usable patterns to match list item bullets and number markers:
 		$marker_ul_re  = '[*+-]';
 		$marker_ol_re  = '\d+[\.]';
 
 		$markers_relist = array(
 			$marker_ul_re => $marker_ol_re,
 			$marker_ol_re => $marker_ul_re,
 			);
 
 		foreach ($markers_relist as $marker_re => $other_marker_re) {
 			// Re-usable pattern to match any entirel ul or ol list:
 			$whole_list_re = '
 				(								# $1 = whole list
 				  (								# $2
 					([ ]{0,'.$less_than_tab.'})	# $3 = number of spaces
 					('.$marker_re.')			# $4 = first list item marker
 					[ ]+
 				  )
 				  (?s:.+?)
 				  (								# $5
 					  \z
 					|
 					  \n{2,}
 					  (?=\S)
 					  (?!						# Negative lookahead for another list item marker
 						[ ]*
 						'.$marker_re.'[ ]+
 					  )
 					|
 					  (?=						# Lookahead for another kind of list
 					    \n
 						\3						# Must have the same indentation
 						'.$other_marker_re.'[ ]+
 					  )
 				  )
 				)
 			'; // mx
 
 			// We use a different prefix before nested lists than top-level lists.
 			//See extended comment in _ProcessListItems().
 
 			if ($this->list_level) {
 				$text = preg_replace_callback('{
 						^
 						'.$whole_list_re.'
 					}mx',
 					array($this, '_doLists_callback'), $text);
 			} else {
 				$text = preg_replace_callback('{
 						(?:(?<=\n)\n|\A\n?) # Must eat the newline
 						'.$whole_list_re.'
 					}mx',
 					array($this, '_doLists_callback'), $text);
 			}
 		}
 
 		return $text;
 	}
 
 	/**
 	 * List parsing callback
 	 * @param  array $matches
 	 * @return string
 	 */
 	protected function _doLists_callback($matches) {
 		// Re-usable patterns to match list item bullets and number markers:
 		$marker_ul_re  = '[*+-]';
 		$marker_ol_re  = '\d+[\.]';
 		$marker_any_re = "(?:$marker_ul_re|$marker_ol_re)";
 		$marker_ol_start_re = '[0-9]+';
 
 		$list = $matches[1];
 		$list_type = preg_match("/$marker_ul_re/", $matches[4]) ? "ul" : "ol";
 
 		$marker_any_re = ( $list_type == "ul" ? $marker_ul_re : $marker_ol_re );
 
 		$list .= "\n";
 		$result = $this->processListItems($list, $marker_any_re);
 
 		$ol_start = 1;
 		if ($this->enhanced_ordered_list) {
 			// Get the start number for ordered list.
 			if ($list_type == 'ol') {
 				$ol_start_array = array();
 				$ol_start_check = preg_match("/$marker_ol_start_re/", $matches[4], $ol_start_array);
 				if ($ol_start_check){
 					$ol_start = $ol_start_array[0];
 				}
 			}
 		}
 
 		if ($ol_start > 1 && $list_type == 'ol'){
 			$result = $this->hashBlock("<$list_type start=\"$ol_start\">\n" . $result . "</$list_type>");
 		} else {
 			$result = $this->hashBlock("<$list_type>\n" . $result . "</$list_type>");
 		}
 		return "\n". $result ."\n\n";
 	}
 
 	/**
 	 * Nesting tracker for list levels
 	 * @var integer
 	 */
 	protected $list_level = 0;
 
 	/**
 	 * Process the contents of a single ordered or unordered list, splitting it
 	 * into individual list items.
 	 * @param  string $list_str
 	 * @param  string $marker_any_re
 	 * @return string
 	 */
 	protected function processListItems($list_str, $marker_any_re) {
 		/**
 		 * The $this->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.".
 		 */
 		$this->list_level++;
 
 		// Trim trailing blank lines:
 		$list_str = preg_replace("/\n{2,}\\z/", "\n", $list_str);
 
 		$list_str = preg_replace_callback('{
 			(\n)?							# leading line = $1
 			(^[ ]*)							# leading whitespace = $2
 			('.$marker_any_re.'				# list marker and space = $3
 				(?:[ ]+|(?=\n))	# space only required if item is not empty
 			)
 			((?s:.*?))						# list item text   = $4
 			(?:(\n+(?=\n))|\n)				# tailing blank line = $5
 			(?= \n* (\z | \2 ('.$marker_any_re.') (?:[ ]+|(?=\n))))
 			}xm',
 			array($this, '_processListItems_callback'), $list_str);
 
 		$this->list_level--;
 		return $list_str;
 	}
 
 	/**
 	 * List item parsing callback
 	 * @param  array $matches
 	 * @return string
 	 */
 	protected function _processListItems_callback($matches) {
 		$item = $matches[4];
 		$leading_line =& $matches[1];
 		$leading_space =& $matches[2];
 		$marker_space = $matches[3];
 		$tailing_blank_line =& $matches[5];
 
 		if ($leading_line || $tailing_blank_line ||
 			preg_match('/\n{2,}/', $item))
 		{
 			// Replace marker with the appropriate whitespace indentation
 			$item = $leading_space . str_repeat(' ', strlen($marker_space)) . $item;
 			$item = $this->runBlockGamut($this->outdent($item)."\n");
 		} else {
 			// Recursion for sub-lists:
 			$item = $this->doLists($this->outdent($item));
 			$item = $this->formParagraphs($item, false);
 		}
 
 		return "<li>" . $item . "</li>\n";
 	}
 
 	/**
 	 * Process Markdown `<pre><code>` blocks.
 	 * @param  string $text
 	 * @return string
 	 */
 	protected function doCodeBlocks($text) {
 		$text = preg_replace_callback('{
 				(?:\n\n|\A\n?)
 				(	            # $1 = the code block -- one or more lines, starting with a space/tab
 				  (?>
 					[ ]{'.$this->tab_width.'}  # Lines must start with a tab or a tab-width of spaces
 					.*\n+
 				  )+
 				)
 				((?=^[ ]{0,'.$this->tab_width.'}\S)|\Z)	# Lookahead for non-space at line-start, or end of doc
 			}xm',
 			array($this, '_doCodeBlocks_callback'), $text);
 
 		return $text;
 	}
 
 	/**
 	 * Code block parsing callback
 	 * @param  array $matches
 	 * @return string
 	 */
 	protected function _doCodeBlocks_callback($matches) {
 		$codeblock = $matches[1];
 
 		$codeblock = $this->outdent($codeblock);
 		if (is_callable($this->code_block_content_func)) {
 			$codeblock = call_user_func($this->code_block_content_func, $codeblock, "");
 		} else {
 			$codeblock = htmlspecialchars($codeblock, ENT_NOQUOTES);
 		}
 
 		# trim leading newlines and trailing newlines
 		$codeblock = preg_replace('/\A\n+|\n+\z/', '', $codeblock);
 
 		$codeblock = "<pre><code>$codeblock\n</code></pre>";
 		return "\n\n" . $this->hashBlock($codeblock) . "\n\n";
 	}
 
 	/**
 	 * Create a code span markup for $code. Called from handleSpanToken.
 	 * @param  string $code
 	 * @return string
 	 */
 	protected function makeCodeSpan($code) {
 		if (is_callable($this->code_span_content_func)) {
 			$code = call_user_func($this->code_span_content_func, $code);
 		} else {
 			$code = htmlspecialchars(trim($code), ENT_NOQUOTES);
 		}
 		return $this->hashPart("<code>$code</code>");
 	}
 
 	/**
 	 * Define the emphasis operators with their regex matches
 	 * @var array
 	 */
 	protected $em_relist = array(
 		''  => '(?:(?<!\*)\*(?!\*)|(?<!_)_(?!_))(?![\.,:;]?\s)',
 		'*' => '(?<![\s*])\*(?!\*)',
 		'_' => '(?<![\s_])_(?!_)',
 	);
 
 	/**
 	 * Define the strong operators with their regex matches
 	 * @var array
 	 */
 	protected $strong_relist = array(
 		''   => '(?:(?<!\*)\*\*(?!\*)|(?<!_)__(?!_))(?![\.,:;]?\s)',
 		'**' => '(?<![\s*])\*\*(?!\*)',
 		'__' => '(?<![\s_])__(?!_)',
 	);
 
 	/**
 	 * Define the emphasis + strong operators with their regex matches
 	 * @var array
 	 */
 	protected $em_strong_relist = array(
 		''    => '(?:(?<!\*)\*\*\*(?!\*)|(?<!_)___(?!_))(?![\.,:;]?\s)',
 		'***' => '(?<![\s*])\*\*\*(?!\*)',
 		'___' => '(?<![\s_])___(?!_)',
 	);
 
 	/**
 	 * Container for prepared regular expressions
 	 * @var array
 	 */
 	protected $em_strong_prepared_relist;
 
 	/**
 	 * Prepare regular expressions for searching emphasis tokens in any
 	 * context.
 	 * @return void
 	 */
 	protected function prepareItalicsAndBold() {
 		foreach ($this->em_relist as $em => $em_re) {
 			foreach ($this->strong_relist as $strong => $strong_re) {
 				// Construct list of allowed token expressions.
 				$token_relist = array();
 				if (isset($this->em_strong_relist["$em$strong"])) {
 					$token_relist[] = $this->em_strong_relist["$em$strong"];
 				}
 				$token_relist[] = $em_re;
 				$token_relist[] = $strong_re;
 
 				// Construct master expression from list.
 				$token_re = '{(' . implode('|', $token_relist) . ')}';
 				$this->em_strong_prepared_relist["$em$strong"] = $token_re;
 			}
 		}
 	}
 
 	/**
 	 * Convert Markdown italics (emphasis) and bold (strong) to HTML
 	 * @param  string $text
 	 * @return string
 	 */
 	protected function doItalicsAndBold($text) {
 		if ($this->in_emphasis_processing) {
 			return $text; // avoid reentrency
 		}
 		$this->in_emphasis_processing = true;
 
 		$token_stack = array('');
 		$text_stack = array('');
 		$em = '';
 		$strong = '';
 		$tree_char_em = false;
 
 		while (1) {
 			// Get prepared regular expression for seraching emphasis tokens
 			// in current context.
 			$token_re = $this->em_strong_prepared_relist["$em$strong"];
 
 			// Each loop iteration search for the next emphasis token.
 			// Each token is then passed to handleSpanToken.
 			$parts = preg_split($token_re, $text, 2, PREG_SPLIT_DELIM_CAPTURE);
 			$text_stack[0] .= $parts[0];
 			$token =& $parts[1];
 			$text =& $parts[2];
 
 			if (empty($token)) {
 				// Reached end of text span: empty stack without emitting.
 				// any more emphasis.
 				while ($token_stack[0]) {
 					$text_stack[1] .= array_shift($token_stack);
 					$text_stack[0] .= array_shift($text_stack);
 				}
 				break;
 			}
 
 			$token_len = strlen($token);
 			if ($tree_char_em) {
 				// Reached closing marker while inside a three-char emphasis.
 				if ($token_len == 3) {
 					// Three-char closing marker, close em and strong.
 					array_shift($token_stack);
 					$span = array_shift($text_stack);
 					$span = $this->runSpanGamut($span);
 					$span = "<strong><em>$span</em></strong>";
 					$text_stack[0] .= $this->hashPart($span);
 					$em = '';
 					$strong = '';
 				} else {
 					// Other closing marker: close one em or strong and
 					// change current token state to match the other
 					$token_stack[0] = str_repeat($token[0], 3-$token_len);
 					$tag = $token_len == 2 ? "strong" : "em";
 					$span = $text_stack[0];
 					$span = $this->runSpanGamut($span);
 					$span = "<$tag>$span</$tag>";
 					$text_stack[0] = $this->hashPart($span);
 					$$tag = ''; // $$tag stands for $em or $strong
 				}
 				$tree_char_em = false;
 			} else if ($token_len == 3) {
 				if ($em) {
 					// Reached closing marker for both em and strong.
 					// Closing strong marker:
 					for ($i = 0; $i < 2; ++$i) {
 						$shifted_token = array_shift($token_stack);
 						$tag = strlen($shifted_token) == 2 ? "strong" : "em";
 						$span = array_shift($text_stack);
 						$span = $this->runSpanGamut($span);
 						$span = "<$tag>$span</$tag>";
 						$text_stack[0] .= $this->hashPart($span);
 						$$tag = ''; // $$tag stands for $em or $strong
 					}
 				} else {
 					// Reached opening three-char emphasis marker. Push on token
 					// stack; will be handled by the special condition above.
 					$em = $token[0];
 					$strong = "$em$em";
 					array_unshift($token_stack, $token);
 					array_unshift($text_stack, '');
 					$tree_char_em = true;
 				}
 			} else if ($token_len == 2) {
 				if ($strong) {
 					// Unwind any dangling emphasis marker:
 					if (strlen($token_stack[0]) == 1) {
 						$text_stack[1] .= array_shift($token_stack);
 						$text_stack[0] .= array_shift($text_stack);
 						$em = '';
 					}
 					// Closing strong marker:
 					array_shift($token_stack);
 					$span = array_shift($text_stack);
 					$span = $this->runSpanGamut($span);
 					$span = "<strong>$span</strong>";
 					$text_stack[0] .= $this->hashPart($span);
 					$strong = '';
 				} else {
 					array_unshift($token_stack, $token);
 					array_unshift($text_stack, '');
 					$strong = $token;
 				}
 			} else {
 				// Here $token_len == 1
 				if ($em) {
 					if (strlen($token_stack[0]) == 1) {
 						// Closing emphasis marker:
 						array_shift($token_stack);
 						$span = array_shift($text_stack);
 						$span = $this->runSpanGamut($span);
 						$span = "<em>$span</em>";
 						$text_stack[0] .= $this->hashPart($span);
 						$em = '';
 					} else {
 						$text_stack[0] .= $token;
 					}
 				} else {
 					array_unshift($token_stack, $token);
 					array_unshift($text_stack, '');
 					$em = $token;
 				}
 			}
 		}
 		$this->in_emphasis_processing = false;
 		return $text_stack[0];
 	}
 
 	/**
 	 * Parse Markdown blockquotes to HTML
 	 * @param  string $text
 	 * @return string
 	 */
 	protected function doBlockQuotes($text) {
 		$text = preg_replace_callback('/
 			  (								# Wrap whole match in $1
 				(?>
 				  ^[ ]*>[ ]?			# ">" at the start of a line
 					.+\n					# rest of the first line
 				  (.+\n)*					# subsequent consecutive lines
 				  \n*						# blanks
 				)+
 			  )
 			/xm',
 			array($this, '_doBlockQuotes_callback'), $text);
 
 		return $text;
 	}
 
 	/**
 	 * Blockquote parsing callback
 	 * @param  array $matches
 	 * @return string
 	 */
 	protected function _doBlockQuotes_callback($matches) {
 		$bq = $matches[1];
 		// trim one level of quoting - trim whitespace-only lines
 		$bq = preg_replace('/^[ ]*>[ ]?|^[ ]+$/m', '', $bq);
 		$bq = $this->runBlockGamut($bq); // recurse
 
 		$bq = preg_replace('/^/m', "  ", $bq);
 		// These leading spaces cause problem with <pre> content,
 		// so we need to fix that:
 		$bq = preg_replace_callback('{(\s*<pre>.+?</pre>)}sx',
 			array($this, '_doBlockQuotes_callback2'), $bq);
 
 		return "\n" . $this->hashBlock("<blockquote>\n$bq\n</blockquote>") . "\n\n";
 	}
 
 	/**
 	 * Blockquote parsing callback
 	 * @param  array $matches
 	 * @return string
 	 */
 	protected function _doBlockQuotes_callback2($matches) {
 		$pre = $matches[1];
 		$pre = preg_replace('/^  /m', '', $pre);
 		return $pre;
 	}
 
 	/**
 	 * Parse paragraphs
 	 *
 	 * @param  string $text String to process in paragraphs
 	 * @param  boolean $wrap_in_p Whether paragraphs should be wrapped in <p> tags
 	 * @return string
 	 */
 	protected function formParagraphs($text, $wrap_in_p = true) {
 		// Strip leading and trailing lines:
 		$text = preg_replace('/\A\n+|\n+\z/', '', $text);
 
 		$grafs = preg_split('/\n{2,}/', $text, -1, PREG_SPLIT_NO_EMPTY);
 
 		// Wrap <p> tags and unhashify HTML blocks
 		foreach ($grafs as $key => $value) {
 			if (!preg_match('/^B\x1A[0-9]+B$/', $value)) {
 				// Is a paragraph.
 				$value = $this->runSpanGamut($value);
 				if ($wrap_in_p) {
 					$value = preg_replace('/^([ ]*)/', "<p>", $value);
 					$value .= "</p>";
 				}
 				$grafs[$key] = $this->unhash($value);
 			} else {
 				// Is a block.
 				// Modify elements of @grafs in-place...
 				$graf = $value;
 				$block = $this->html_hashes[$graf];
 				$graf = $block;
 //				if (preg_match('{
 //					\A
 //					(							# $1 = <div> tag
 //					  <div  \s+
 //					  [^>]*
 //					  \b
 //					  markdown\s*=\s*  ([\'"])	#	$2 = attr quote char
 //					  1
 //					  \2
 //					  [^>]*
 //					  >
 //					)
 //					(							# $3 = contents
 //					.*
 //					)
 //					(</div>)					# $4 = closing tag
 //					\z
 //					}xs', $block, $matches))
 //				{
 //					list(, $div_open, , $div_content, $div_close) = $matches;
 //
 //					// We can't call Markdown(), because that resets the hash;
 //					// that initialization code should be pulled into its own sub, though.
 //					$div_content = $this->hashHTMLBlocks($div_content);
 //
 //					// Run document gamut methods on the content.
 //					foreach ($this->document_gamut as $method => $priority) {
 //						$div_content = $this->$method($div_content);
 //					}
 //
 //					$div_open = preg_replace(
 //						'{\smarkdown\s*=\s*([\'"]).+?\1}', '', $div_open);
 //
 //					$graf = $div_open . "\n" . $div_content . "\n" . $div_close;
 //				}
 				$grafs[$key] = $graf;
 			}
 		}
 
 		return implode("\n\n", $grafs);
 	}
 
 	/**
 	 * Encode text for a double-quoted HTML attribute. This function
 	 * is *not* suitable for attributes enclosed in single quotes.
 	 * @param  string $text
 	 * @return string
 	 */
 	protected function encodeAttribute($text) {
 		$text = $this->encodeAmpsAndAngles($text);
 		$text = str_replace('"', '&quot;', $text);
 		return $text;
 	}
 
 	/**
 	 * Encode text for a double-quoted HTML attribute containing a URL,
 	 * applying the URL filter if set. Also generates the textual
 	 * representation for the URL (removing mailto: or tel:) storing it in $text.
 	 * This function is *not* suitable for attributes enclosed in single quotes.
 	 *
 	 * @param  string $url
 	 * @param  string $text Passed by reference
 	 * @return string        URL
 	 */
 	protected function encodeURLAttribute($url, &$text = null) {
 		if (is_callable($this->url_filter_func)) {
 			$url = call_user_func($this->url_filter_func, $url);
 		}
 
 		if (preg_match('{^mailto:}i', $url)) {
 			$url = $this->encodeEntityObfuscatedAttribute($url, $text, 7);
 		} else if (preg_match('{^tel:}i', $url)) {
 			$url = $this->encodeAttribute($url);
 			$text = substr($url, 4);
 		} else {
 			$url = $this->encodeAttribute($url);
 			$text = $url;
 		}
 
 		return $url;
 	}
 
 	/**
 	 * Smart processing for ampersands and angle brackets that need to
 	 * be encoded. Valid character entities are left alone unless the
 	 * no-entities mode is set.
 	 * @param  string $text
 	 * @return string
 	 */
 	protected function encodeAmpsAndAngles($text) {
 		if ($this->no_entities) {
 			$text = str_replace('&', '&amp;', $text);
 		} else {
 			// Ampersand-encoding based entirely on Nat Irons's Amputator
 			// MT plugin: <http://bumppo.net/projects/amputator/>
 			$text = preg_replace('/&(?!#?[xX]?(?:[0-9a-fA-F]+|\w+);)/',
 								'&amp;', $text);
 		}
 		// Encode remaining <'s
 		$text = str_replace('<', '&lt;', $text);
 
 		return $text;
 	}
 
 	/**
 	 * Parse Markdown automatic links to anchor HTML tags
 	 * @param  string $text
 	 * @return string
 	 */
 	protected function doAutoLinks($text) {
 		$text = preg_replace_callback('{<((https?|ftp|dict|tel):[^\'">\s]+)>}i',
 			array($this, '_doAutoLinks_url_callback'), $text);
 
 		// Email addresses: <address@domain.foo>
 		$text = preg_replace_callback('{
 			<
 			(?:mailto:)?
 			(
 				(?:
 					[-!#$%&\'*+/=?^_`.{|}~\w\x80-\xFF]+
 				|
 					".*?"
 				)
 				\@
 				(?:
 					[-a-z0-9\x80-\xFF]+(\.[-a-z0-9\x80-\xFF]+)*\.[a-z]+
 				|
 					\[[\d.a-fA-F:]+\]	# IPv4 & IPv6
 				)
 			)
 			>
 			}xi',
 			array($this, '_doAutoLinks_email_callback'), $text);
 
 		return $text;
 	}
 
 	/**
 	 * Parse URL callback
 	 * @param  array $matches
 	 * @return string
 	 */
 	protected function _doAutoLinks_url_callback($matches) {
 		$url = $this->encodeURLAttribute($matches[1], $text);
 		$link = "<a href=\"$url\">$text</a>";
 		return $this->hashPart($link);
 	}
 
 	/**
 	 * Parse email address callback
 	 * @param  array $matches
 	 * @return string
 	 */
 	protected function _doAutoLinks_email_callback($matches) {
 		$addr = $matches[1];
 		$url = $this->encodeURLAttribute("mailto:$addr", $text);
 		$link = "<a href=\"$url\">$text</a>";
 		return $this->hashPart($link);
 	}
 
 	/**
 	 * Input: some text to obfuscate, e.g. "mailto:foo@example.com"
 	 *
 	 * Output: the same text but with most characters encoded as either a
 	 *         decimal or hex entity, in the hopes of foiling most address
 	 *         harvesting spam bots. E.g.:
 	 *
 	 *        &#109;&#x61;&#105;&#x6c;&#116;&#x6f;&#58;&#x66;o&#111;
 	 *        &#x40;&#101;&#x78;&#97;&#x6d;&#112;&#x6c;&#101;&#46;&#x63;&#111;
 	 *        &#x6d;
 	 *
 	 * Note: the additional output $tail is assigned the same value as the
 	 * ouput, minus the number of characters specified by $head_length.
 	 *
 	 * Based by a filter by Matthew Wickline, posted to BBEdit-Talk.
 	 * With some optimizations by Milian Wolff. Forced encoding of HTML
 	 * attribute special characters by Allan Odgaard.
 	 *
 	 * @param  string  $text
 	 * @param  string  $tail Passed by reference
 	 * @param  integer $head_length
 	 * @return string
 	 */
 	protected function encodeEntityObfuscatedAttribute($text, &$tail = null, $head_length = 0) {
 		if ($text == "") {
 			return $tail = "";
 		}
 
 		$chars = preg_split('/(?<!^)(?!$)/', $text);
 		$seed = (int)abs(crc32($text) / strlen($text)); // Deterministic seed.
 
 		foreach ($chars as $key => $char) {
 			$ord = ord($char);
 			// Ignore non-ascii chars.
 			if ($ord < 128) {
 				$r = ($seed * (1 + $key)) % 100; // Pseudo-random function.
 				// roughly 10% raw, 45% hex, 45% dec
 				// '@' *must* be encoded. I insist.
 				// '"' and '>' have to be encoded inside the attribute
 				if ($r > 90 && strpos('@"&>', $char) === false) {
 					/* do nothing */
 				} else if ($r < 45) {
 					$chars[$key] = '&#x'.dechex($ord).';';
 				} else {
 					$chars[$key] = '&#'.$ord.';';
 				}
 			}
 		}
 
 		$text = implode('', $chars);
 		$tail = $head_length ? implode('', array_slice($chars, $head_length)) : $text;
 
 		return $text;
 	}
 
 	/**
 	 * Take the string $str and parse it into tokens, hashing embeded HTML,
 	 * escaped characters and handling code spans.
 	 * @param  string $str
 	 * @return string
 	 */
 	protected function parseSpan($str) {
 		$output = '';
 
 		$span_re = '{
 				(
 					\\\\'.$this->escape_chars_re.'
 				|
 					(?<![`\\\\])
 					`+						# code span marker
 			'.( $this->no_markup ? '' : '
 				|
 					<!--    .*?     -->		# comment
 				|
 					<\?.*?\?> | <%.*?%>		# processing instruction
 				|
 					<[!$]?[-a-zA-Z0-9:_]+	# regular tags
 					(?>
 						\s
 						(?>[^"\'>]+|"[^"]*"|\'[^\']*\')*
 					)?
 					>
 				|
 					<[-a-zA-Z0-9:_]+\s*/> # xml-style empty tag
 				|
 					</[-a-zA-Z0-9:_]+\s*> # closing tag
 			').'
 				)
 				}xs';
 
 		while (1) {
 			// Each loop iteration seach for either the next tag, the next
 			// openning code span marker, or the next escaped character.
 			// Each token is then passed to handleSpanToken.
 			$parts = preg_split($span_re, $str, 2, PREG_SPLIT_DELIM_CAPTURE);
 
 			// Create token from text preceding tag.
 			if ($parts[0] != "") {
 				$output .= $parts[0];
 			}
 
 			// Check if we reach the end.
 			if (isset($parts[1])) {
 				$output .= $this->handleSpanToken($parts[1], $parts[2]);
 				$str = $parts[2];
 			} else {
 				break;
 			}
 		}
 
 		return $output;
 	}
 
 	/**
 	 * Handle $token provided by parseSpan by determining its nature and
 	 * returning the corresponding value that should replace it.
 	 * @param  string $token
 	 * @param  string $str Passed by reference
 	 * @return string
 	 */
 	protected function handleSpanToken($token, &$str) {
 		switch ($token[0]) {
 			case "\\":
 				return $this->hashPart("&#". ord($token[1]). ";");
 			case "`":
 				// Search for end marker in remaining text.
 				if (preg_match('/^(.*?[^`])'.preg_quote($token).'(?!`)(.*)$/sm',
 					$str, $matches))
 				{
 					$str = $matches[2];
 					$codespan = $this->makeCodeSpan($matches[1]);
 					return $this->hashPart($codespan);
 				}
 				return $token; // Return as text since no ending marker found.
 			default:
 				return $this->hashPart($token);
 		}
 	}
 
 	/**
 	 * Remove one level of line-leading tabs or spaces
 	 * @param  string $text
 	 * @return string
 	 */
 	protected function outdent($text) {
 		return preg_replace('/^(\t|[ ]{1,' . $this->tab_width . '})/m', '', $text);
 	}
 
 
 	/**
 	 * String length function for detab. `_initDetab` will create a function to
 	 * handle UTF-8 if the default function does not exist.
 	 * @var string
 	 */
 	protected $utf8_strlen = 'mb_strlen';
 
 	/**
 	 * Replace tabs with the appropriate amount of spaces.
 	 *
 	 * For each line we separate the line in blocks delemited by tab characters.
 	 * Then we reconstruct every line by adding the  appropriate number of space
 	 * between each blocks.
 	 *
 	 * @param  string $text
 	 * @return string
 	 */
 	protected function detab($text) {
 		$text = preg_replace_callback('/^.*\t.*$/m',
 			array($this, '_detab_callback'), $text);
 
 		return $text;
 	}
 
 	/**
 	 * Replace tabs callback
 	 * @param  string $matches
 	 * @return string
 	 */
 	protected function _detab_callback($matches) {
 		$line = $matches[0];
 		$strlen = $this->utf8_strlen; // strlen function for UTF-8.
 
 		// Split in blocks.
 		$blocks = explode("\t", $line);
 		// Add each blocks to the line.
 		$line = $blocks[0];
 		unset($blocks[0]); // Do not add first block twice.
 		foreach ($blocks as $block) {
 			// Calculate amount of space, insert spaces, insert block.
 			$amount = $this->tab_width -
 				$strlen($line, 'UTF-8') % $this->tab_width;
 			$line .= str_repeat(" ", $amount) . $block;
 		}
 		return $line;
 	}
 
 	/**
 	 * Check for the availability of the function in the `utf8_strlen` property
 	 * (initially `mb_strlen`). If the function is not available, create a
 	 * function that will loosely count the number of UTF-8 characters with a
 	 * regular expression.
 	 * @return void
 	 */
 	protected function _initDetab() {
 
 		if (function_exists($this->utf8_strlen)) {
 			return;
 		}
 
 		$this->utf8_strlen = function($text) {
 			return preg_match_all('/[\x00-\xBF]|[\xC0-\xFF][\x80-\xBF]*/', $text, $m);
 		};
 	}
 
 	/**
 	 * Swap back in all the tags hashed by _HashHTMLBlocks.
 	 * @param  string $text
 	 * @return string
 	 */
 	protected function unhash($text) {
 		return preg_replace_callback('/(.)\x1A[0-9]+\1/',
 			array($this, '_unhash_callback'), $text);
 	}
 
 	/**
 	 * Unhashing callback
 	 * @param  array $matches
 	 * @return string
 	 */
 	protected function _unhash_callback($matches) {
 		return $this->html_hashes[$matches[0]];
 	}
 }
 
 class MarkdownExtraParser extends MarkdownParser {
 	/**
 	 * Configuration variables
 	 */
 
 	/**
 	 * Prefix for footnote ids.
 	 * @var string
 	 */
 	public $fn_id_prefix = "";
 
 	/**
 	 * Optional title attribute for footnote links.
 	 * @var string
 	 */
 	public $fn_link_title = "";
 
 	/**
 	 * Optional class attribute for footnote links and backlinks.
 	 * @var string
 	 */
 	public $fn_link_class     = "footnote-ref";
 	public $fn_backlink_class = "footnote-backref";
 
 	/**
 	 * Content to be displayed within footnote backlinks. The default is '↩';
 	 * the U+FE0E on the end is a Unicode variant selector used to prevent iOS
 	 * from displaying the arrow character as an emoji.
 	 * Optionally use '^^' and '%%' to refer to the footnote number and
 	 * reference number respectively. {@see parseFootnotePlaceholders()}
 	 * @var string
 	 */
 	public $fn_backlink_html = '&#8617;&#xFE0E;';
 
 	/**
 	 * Optional title and aria-label attributes for footnote backlinks for
 	 * added accessibility (to ensure backlink uniqueness).
 	 * Use '^^' and '%%' to refer to the footnote number and reference number
 	 * respectively. {@see parseFootnotePlaceholders()}
 	 * @var string
 	 */
 	public $fn_backlink_title = "";
 	public $fn_backlink_label = "";
 
 	/**
 	 * Class name for table cell alignment (%% replaced left/center/right)
 	 * For instance: 'go-%%' becomes 'go-left' or 'go-right' or 'go-center'
 	 * If empty, the align attribute is used instead of a class name.
 	 * @var string
 	 */
 	public $table_align_class_tmpl = '';
 
 	/**
 	 * Optional class prefix for fenced code block.
 	 * @var string
 	 */
 	public $code_class_prefix = "";
 
 	/**
 	 * Class attribute for code blocks goes on the `code` tag;
 	 * setting this to true will put attributes on the `pre` tag instead.
 	 * @var boolean
 	 */
 	public $code_attr_on_pre = false;
 
 	/**
 	 * Predefined abbreviations.
 	 * @var array
 	 */
 	public $predef_abbr = array();
 
 	/**
 	 * Only convert atx-style headers if there's a space between the header and #
 	 * @var boolean
 	 */
 	public $hashtag_protection = false;
 
 	/**
 	 * Determines whether footnotes should be appended to the end of the document.
 	 * If true, footnote html can be retrieved from $this->footnotes_assembled.
 	 * @var boolean
 	 */
 	public $omit_footnotes = false;
 
 
 	/**
 	 * After parsing, the HTML for the list of footnotes appears here.
 	 * This is available only if $omit_footnotes == true.
 	 *
 	 * Note: when placing the content of `footnotes_assembled` on the page,
 	 * consider adding the attribute `role="doc-endnotes"` to the `div` or
 	 * `section` that will enclose the list of footnotes so they are
 	 * reachable to accessibility tools the same way they would be with the
 	 * default HTML output.
 	 * @var null|string
 	 */
 	public $footnotes_assembled = null;
 
 	/**
 	 * Parser implementation
 	 */
 
 	/**
 	 * Constructor function. Initialize the parser object.
 	 * @return void
 	 */
 	public function __construct() {
 		// Add extra escapable characters before parent constructor
 		// initialize the table.
 		$this->escape_chars .= ':|';
 
 		// Insert extra document, block, and span transformations.
 		// Parent constructor will do the sorting.
 		$this->document_gamut += array(
 			"doFencedCodeBlocks" => 5,
 			"stripFootnotes"     => 15,
 			"stripAbbreviations" => 25,
 			"appendFootnotes"    => 50,
 		);
 		$this->block_gamut += array(
 			"doFencedCodeBlocks" => 5,
 			"doTables"           => 15,
 			"doDefLists"         => 45,
 		);
 		$this->span_gamut += array(
 			"doFootnotes"        => 5,
 			"doAbbreviations"    => 70,
 		);
 
 		$this->enhanced_ordered_list = true;
 		parent::__construct();
 	}
 
 
 	/**
 	 * Extra variables used during extra transformations.
 	 * @var array
 	 */
 	protected $footnotes = array();
 	protected $footnotes_ordered = array();
 	protected $footnotes_ref_count = array();
 	protected $footnotes_numbers = array();
 	protected $abbr_desciptions = array();
 	/** @var string */
 	protected $abbr_word_re = '';
 
 	/**
 	 * Give the current footnote number.
 	 * @var integer
 	 */
 	protected $footnote_counter = 1;
 
     /**
      * Ref attribute for links
      * @var array
      */
 	protected $ref_attr = array();
 
 	/**
 	 * Setting up Extra-specific variables.
 	 */
 	protected function setup() {
 		parent::setup();
 
 		$this->footnotes = array();
 		$this->footnotes_ordered = array();
 		$this->footnotes_ref_count = array();
 		$this->footnotes_numbers = array();
 		$this->abbr_desciptions = array();
 		$this->abbr_word_re = '';
 		$this->footnote_counter = 1;
 		$this->footnotes_assembled = null;
 
 		foreach ($this->predef_abbr as $abbr_word => $abbr_desc) {
 			if ($this->abbr_word_re)
 				$this->abbr_word_re .= '|';
 			$this->abbr_word_re .= preg_quote($abbr_word);
 			$this->abbr_desciptions[$abbr_word] = trim($abbr_desc);
 		}
 	}
 
 	/**
 	 * Clearing Extra-specific variables.
 	 */
 	protected function teardown() {
 		$this->footnotes = array();
 		$this->footnotes_ordered = array();
 		$this->footnotes_ref_count = array();
 		$this->footnotes_numbers = array();
 		$this->abbr_desciptions = array();
 		$this->abbr_word_re = '';
 
 		if ( ! $this->omit_footnotes )
 			$this->footnotes_assembled = null;
 
 		parent::teardown();
 	}
 
 
 	/**
 	 * Extra attribute parser
 	 */
 
 	/**
 	 * Expression to use to catch attributes (includes the braces)
 	 * @var string
 	 */
 	protected $id_class_attr_catch_re = '\{((?>[ ]*[#.a-z][-_:a-zA-Z0-9=]+){1,})[ ]*\}';
 
 	/**
 	 * Expression to use when parsing in a context when no capture is desired
 	 * @var string
 	 */
 	protected $id_class_attr_nocatch_re = '\{(?>[ ]*[#.a-z][-_:a-zA-Z0-9=]+){1,}[ ]*\}';
 
 	/**
 	 * Parse attributes caught by the $this->id_class_attr_catch_re expression
 	 * and return the HTML-formatted list of attributes.
 	 *
 	 * Currently supported attributes are .class and #id.
 	 *
 	 * In addition, this method also supports supplying a default Id value,
 	 * which will be used to populate the id attribute in case it was not
 	 * overridden.
 	 * @param  string $tag_name
 	 * @param  string $attr
 	 * @param  mixed  $defaultIdValue
 	 * @param  array  $classes
 	 * @return string
 	 */
 	protected function doExtraAttributes($tag_name, $attr, $defaultIdValue = null, $classes = array()) {
 		if (empty($attr) && !$defaultIdValue && empty($classes)) {
 			return "";
 		}
 
 		// Split on components
 		preg_match_all('/[#.a-z][-_:a-zA-Z0-9=]+/', $attr, $matches);
 		$elements = $matches[0];
 
 		// Handle classes and IDs (only first ID taken into account)
 		$attributes = array();
 		$id = false;
 		foreach ($elements as $element) {
 			if ($element[0] === '.') {
 				$classes[] = substr($element, 1);
 			} else if ($element[0] === '#') {
 				if ($id === false) $id = substr($element, 1);
 			} else if (strpos($element, '=') > 0) {
 				$parts = explode('=', $element, 2);
 				$attributes[] = $parts[0] . '="' . $parts[1] . '"';
 			}
 		}
 
 		if ($id === false || $id === '') {
 			$id = $defaultIdValue;
 		}
 
 		// Compose attributes as string
 		$attr_str = "";
 		if (!empty($id)) {
 			$attr_str .= ' id="'.$this->encodeAttribute($id) .'"';
 		}
 		if (!empty($classes)) {
 			$attr_str .= ' class="'. implode(" ", $classes) . '"';
 		}
 		if (!$this->no_markup && !empty($attributes)) {
 			$attr_str .= ' '.implode(" ", $attributes);
 		}
 		return $attr_str;
 	}
 
 	/**
 	 * Strips link definitions from text, stores the URLs and titles in
 	 * hash references.
 	 * @param  string $text
 	 * @return string
 	 */
 	protected function stripLinkDefinitions($text) {
 		$less_than_tab = $this->tab_width - 1;
 
 		// Link defs are in the form: ^[id]: url "optional title"
 		$text = preg_replace_callback('{
 							^[ ]{0,'.$less_than_tab.'}\[(.+)\][ ]?:	# id = $1
 							  [ ]*
 							  \n?				# maybe *one* newline
 							  [ ]*
 							(?:
 							  <(.+?)>			# url = $2
 							|
 							  (\S+?)			# url = $3
 							)
 							  [ ]*
 							  \n?				# maybe one newline
 							  [ ]*
 							(?:
 								(?<=\s)			# lookbehind for whitespace
 								["(]
 								(.*?)			# title = $4
 								[")]
 								[ ]*
 							)?	# title is optional
 					(?:[ ]* '.$this->id_class_attr_catch_re.' )?  # $5 = extra id & class attr
 							(?:\n+|\Z)
 			}xm',
 			array($this, '_stripLinkDefinitions_callback'),
 			$text);
 		return $text;
 	}
 
 	/**
 	 * Strip link definition callback
 	 * @param  array $matches
 	 * @return string
 	 */
 	protected function _stripLinkDefinitions_callback($matches) {
 		$link_id = strtolower($matches[1]);
 		$url = $matches[2] == '' ? $matches[3] : $matches[2];
 		$this->urls[$link_id] = $url;
 		$this->titles[$link_id] =& $matches[4];
 		$this->ref_attr[$link_id] = $this->doExtraAttributes("", $dummy =& $matches[5]);
 		return ''; // String that will replace the block
 	}
 
 
 	/**
 	 * HTML block parser
 	 */
 
 	/**
 	 * Tags that are always treated as block tags
 	 * @var string
 	 */
 	protected $block_tags_re = 'p|div|h[1-6]|blockquote|pre|table|dl|ol|ul|address|form|fieldset|iframe|hr|legend|article|section|nav|aside|hgroup|header|footer|figcaption|figure|details|summary';
 
 	/**
 	 * Tags treated as block tags only if the opening tag is alone on its line
 	 * @var string
 	 */
 	protected $context_block_tags_re = 'script|noscript|style|ins|del|iframe|object|source|track|param|math|svg|canvas|audio|video';
 
 	/**
 	 * Tags where markdown="1" default to span mode:
 	 * @var string
 	 */
 	protected $contain_span_tags_re = 'p|h[1-6]|li|dd|dt|td|th|legend|address';
 
 	/**
 	 * Tags which must not have their contents modified, no matter where
 	 * they appear
 	 * @var string
 	 */
 	protected $clean_tags_re = 'script|style|math|svg';
 
 	/**
 	 * Tags that do not need to be closed.
 	 * @var string
 	 */
 	protected $auto_close_tags_re = 'hr|img|param|source|track';
 
 	/**
 	 * Hashify HTML Blocks and "clean tags".
 	 *
 	 * 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.
 	 *
 	 * This works by calling _HashHTMLBlocks_InMarkdown, which then calls
 	 * _HashHTMLBlocks_InHTML when it encounter block tags. When the markdown="1"
 	 * attribute is found within a tag, _HashHTMLBlocks_InHTML calls back
 	 *  _HashHTMLBlocks_InMarkdown to handle the Markdown syntax within the tag.
 	 * These two functions are calling each other. It's recursive!
 	 * @param  string $text
 	 * @return string
 	 */
 	protected function hashHTMLBlocks($text) {
 		if ($this->no_markup) {
 			return $text;
 		}
 
 		// Call the HTML-in-Markdown hasher.
 		list($text, ) = $this->_hashHTMLBlocks_inMarkdown($text);
 
 		return $text;
 	}
 
 	/**
 	 * Parse markdown text, calling _HashHTMLBlocks_InHTML for block tags.
 	 *
 	 * *   $indent is the number of space to be ignored when checking for code
 	 *     blocks. This is important because if we don't take the indent into
 	 *     account, something like this (which looks right) won't work as expected:
 	 *
 	 *     <div>
 	 *         <div markdown="1">
 	 *         Hello World.  <-- Is this a Markdown code block or text?
 	 *         </div>  <-- Is this a Markdown code block or a real tag?
 	 *     <div>
 	 *
 	 *     If you don't like this, just don't indent the tag on which
 	 *     you apply the markdown="1" attribute.
 	 *
 	 * *   If $enclosing_tag_re is not empty, stops at the first unmatched closing
 	 *     tag with that name. Nested tags supported.
 	 *
 	 * *   If $span is true, text inside must treated as span. So any double
 	 *     newline will be replaced by a single newline so that it does not create
 	 *     paragraphs.
 	 *
 	 * Returns an array of that form: ( processed text , remaining text )
 	 *
 	 * @param  string  $text
 	 * @param  integer $indent
 	 * @param  string  $enclosing_tag_re
 	 * @param  boolean $span
 	 * @return array
 	 */
 	protected function _hashHTMLBlocks_inMarkdown($text, $indent = 0,
 										$enclosing_tag_re = '', $span = false)
 	{
 
 		if ($text === '') return array('', '');
 
 		// Regex to check for the presense of newlines around a block tag.
 		$newline_before_re = '/(?:^\n?|\n\n)*$/';
 		$newline_after_re =
 			'{
 				^						# Start of text following the tag.
 				(?>[ ]*<!--.*?-->)?		# Optional comment.
 				[ ]*\n					# Must be followed by newline.
 			}xs';
 
 		// Regex to match any tag.
 		$block_tag_re =
 			'{
 				(					# $2: Capture whole tag.
 					</?					# Any opening or closing tag.
 						(?>				# Tag name.
 							' . $this->block_tags_re . '			|
 							' . $this->context_block_tags_re . '	|
 							' . $this->clean_tags_re . '        	|
 							(?!\s)'.$enclosing_tag_re . '
 						)
 						(?:
 							(?=[\s"\'/a-zA-Z0-9])	# Allowed characters after tag name.
 							(?>
 								".*?"		|	# Double quotes (can contain `>`)
 								\'.*?\'   	|	# Single quotes (can contain `>`)
 								.+?				# Anything but quotes and `>`.
 							)*?
 						)?
 					>					# End of tag.
 				|
 					<!--    .*?     -->	# HTML Comment
 				|
 					<\?.*?\?> | <%.*?%>	# Processing instruction
 				|
 					<!\[CDATA\[.*?\]\]>	# CData Block
 				' . ( !$span ? ' # If not in span.
 				|
 					# Indented code block
 					(?: ^[ ]*\n | ^ | \n[ ]*\n )
 					[ ]{' . ($indent + 4) . '}[^\n]* \n
 					(?>
 						(?: [ ]{' . ($indent + 4) . '}[^\n]* | [ ]* ) \n
 					)*
 				|
 					# Fenced code block marker
 					(?<= ^ | \n )
 					[ ]{0,' . ($indent + 3) . '}(?:~{3,}|`{3,})
 					[ ]*
 					(?: \.?[-_:a-zA-Z0-9]+ )? # standalone class name
 					[ ]*
 					(?: ' . $this->id_class_attr_nocatch_re . ' )? # extra attributes
 					[ ]*
 					(?= \n )
 				' : '' ) . ' # End (if not is span).
 				|
 					# Code span marker
 					# Note, this regex needs to go after backtick fenced
 					# code blocks but it should also be kept outside of the
 					# "if not in span" condition adding backticks to the parser
 					`+
 				)
 			}xs';
 
 
 		$depth = 0;		// Current depth inside the tag tree.
 		$parsed = "";	// Parsed text that will be returned.
 
 		// Loop through every tag until we find the closing tag of the parent
 		// or loop until reaching the end of text if no parent tag specified.
 		do {
 			// Split the text using the first $tag_match pattern found.
 			// Text before  pattern will be first in the array, text after
 			// pattern will be at the end, and between will be any catches made
 			// by the pattern.
 			$parts = preg_split($block_tag_re, $text, 2,
 								PREG_SPLIT_DELIM_CAPTURE);
 
 			// If in Markdown span mode, add a empty-string span-level hash
 			// after each newline to prevent triggering any block element.
 			if ($span) {
 				$void = $this->hashPart("", ':');
 				$newline = "\n$void";
 				$parts[0] = $void . str_replace("\n", $newline, $parts[0]) . $void;
 			}
 
 			$parsed .= $parts[0]; // Text before current tag.
 
 			// If end of $text has been reached. Stop loop.
 			if (count($parts) < 3) {
 				$text = "";
 				break;
 			}
 
 			$tag  = $parts[1]; // Tag to handle.
 			$text = $parts[2]; // Remaining text after current tag.
 
 			// Check for: Fenced code block marker.
 			// Note: need to recheck the whole tag to disambiguate backtick
 			// fences from code spans
 			if (preg_match('{^\n?([ ]{0,' . ($indent + 3) . '})(~{3,}|`{3,})[ ]*(?:\.?[-_:a-zA-Z0-9]+)?[ ]*(?:' . $this->id_class_attr_nocatch_re . ')?[ ]*\n?$}', $tag, $capture)) {
 				// Fenced code block marker: find matching end marker.
 				$fence_indent = strlen($capture[1]); // use captured indent in re
 				$fence_re = $capture[2]; // use captured fence in re
 				if (preg_match('{^(?>.*\n)*?[ ]{' . ($fence_indent) . '}' . $fence_re . '[ ]*(?:\n|$)}', $text,
 					$matches))
 				{
 					// End marker found: pass text unchanged until marker.
 					$parsed .= $tag . $matches[0];
 					$text = substr($text, strlen($matches[0]));
 				}
 				else {
 					// No end marker: just skip it.
 					$parsed .= $tag;
 				}
 			}
 			// Check for: Indented code block.
 			else if ($tag[0] === "\n" || $tag[0] === " ") {
 				// Indented code block: pass it unchanged, will be handled
 				// later.
 				$parsed .= $tag;
 			}
 			// Check for: Code span marker
 			// Note: need to check this after backtick fenced code blocks
 			else if ($tag[0] === "`") {
 				// Find corresponding end marker.
 				$tag_re = preg_quote($tag);
 				if (preg_match('{^(?>.+?|\n(?!\n))*?(?<!`)' . $tag_re . '(?!`)}',
 					$text, $matches))
 				{
 					// End marker found: pass text unchanged until marker.
 					$parsed .= $tag . $matches[0];
 					$text = substr($text, strlen($matches[0]));
 				}
 				else {
 					// Unmatched marker: just skip it.
 					$parsed .= $tag;
 				}
 			}
 			// Check for: Opening Block level tag or
 			//            Opening Context Block tag (like ins and del)
 			//               used as a block tag (tag is alone on it's line).
 			else if (preg_match('{^<(?:' . $this->block_tags_re . ')\b}', $tag) ||
 				(	preg_match('{^<(?:' . $this->context_block_tags_re . ')\b}', $tag) &&
 					preg_match($newline_before_re, $parsed) &&
 					preg_match($newline_after_re, $text)	)
 				)
 			{
 				// Need to parse tag and following text using the HTML parser.
 				list($block_text, $text) =
 					$this->_hashHTMLBlocks_inHTML($tag . $text, "hashBlock", true);
 
 				// Make sure it stays outside of any paragraph by adding newlines.
 				$parsed .= "\n\n$block_text\n\n";
 			}
 			// Check for: Clean tag (like script, math)
 			//            HTML Comments, processing instructions.
 			else if (preg_match('{^<(?:' . $this->clean_tags_re . ')\b}', $tag) ||
 				$tag[1] === '!' || $tag[1] === '?')
 			{
 				// Need to parse tag and following text using the HTML parser.
 				// (don't check for markdown attribute)
 				list($block_text, $text) =
 					$this->_hashHTMLBlocks_inHTML($tag . $text, "hashClean", false);
 
 				$parsed .= $block_text;
 			}
 			// Check for: Tag with same name as enclosing tag.
 			else if ($enclosing_tag_re !== '' &&
 				// Same name as enclosing tag.
 				preg_match('{^</?(?:' . $enclosing_tag_re . ')\b}', $tag))
 			{
 				// Increase/decrease nested tag count.
 				if ($tag[1] === '/') {
 					$depth--;
 				} else if ($tag[strlen($tag)-2] !== '/') {
 					$depth++;
 				}
 
 				if ($depth < 0) {
 					// Going out of parent element. Clean up and break so we
 					// return to the calling function.
 					$text = $tag . $text;
 					break;
 				}
 
 				$parsed .= $tag;
 			}
 			else {
 				$parsed .= $tag;
 			}
 		} while ($depth >= 0);
 
 		return array($parsed, $text);
 	}
 
 	/**
 	 * Parse HTML, calling _HashHTMLBlocks_InMarkdown for block tags.
 	 *
 	 * *   Calls $hash_method to convert any blocks.
 	 * *   Stops when the first opening tag closes.
 	 * *   $md_attr indicate if the use of the `markdown="1"` attribute is allowed.
 	 *     (it is not inside clean tags)
 	 *
 	 * Returns an array of that form: ( processed text , remaining text )
 	 * @param  string $text
 	 * @param  string $hash_method
 	 * @param  bool $md_attr Handle `markdown="1"` attribute
 	 * @return array
 	 */
 	protected function _hashHTMLBlocks_inHTML($text, $hash_method, $md_attr) {
 		if ($text === '') return array('', '');
 
 		// Regex to match `markdown` attribute inside of a tag.
 		$markdown_attr_re = '
 			{
 				\s*			# Eat whitespace before the `markdown` attribute
 				markdown
 				\s*=\s*
 				(?>
 					(["\'])		# $1: quote delimiter
 					(.*?)		# $2: attribute value
 					\1			# matching delimiter
 				|
 					([^\s>]*)	# $3: unquoted attribute value
 				)
 				()				# $4: make $3 always defined (avoid warnings)
 			}xs';
 
 		// Regex to match any tag.
 		$tag_re = '{
 				(					# $2: Capture whole tag.
 					</?					# Any opening or closing tag.
 						[\w:$]+			# Tag name.
 						(?:
 							(?=[\s"\'/a-zA-Z0-9])	# Allowed characters after tag name.
 							(?>
 								".*?"		|	# Double quotes (can contain `>`)
 								\'.*?\'   	|	# Single quotes (can contain `>`)
 								.+?				# Anything but quotes and `>`.
 							)*?
 						)?
 					>					# End of tag.
 				|
 					<!--    .*?     -->	# HTML Comment
 				|
 					<\?.*?\?> | <%.*?%>	# Processing instruction
 				|
 					<!\[CDATA\[.*?\]\]>	# CData Block
 				)
 			}xs';
 
 		$original_text = $text;		// Save original text in case of faliure.
 
 		$depth		= 0;	// Current depth inside the tag tree.
 		$block_text	= "";	// Temporary text holder for current text.
 		$parsed		= "";	// Parsed text that will be returned.
 		$base_tag_name_re = '';
 
 		// Get the name of the starting tag.
 		// (This pattern makes $base_tag_name_re safe without quoting.)
 		if (preg_match('/^<([\w:$]*)\b/', $text, $matches))
 			$base_tag_name_re = $matches[1];
 
 		// Loop through every tag until we find the corresponding closing tag.
 		do {
 			// Split the text using the first $tag_match pattern found.
 			// Text before  pattern will be first in the array, text after
 			// pattern will be at the end, and between will be any catches made
 			// by the pattern.
 			$parts = preg_split($tag_re, $text, 2, PREG_SPLIT_DELIM_CAPTURE);
 
 			if (count($parts) < 3) {
 				// End of $text reached with unbalenced tag(s).
 				// In that case, we return original text unchanged and pass the
 				// first character as filtered to prevent an infinite loop in the
 				// parent function.
 				return array($original_text[0], substr($original_text, 1));
 			}
 
 			$block_text .= $parts[0]; // Text before current tag.
 			$tag         = $parts[1]; // Tag to handle.
 			$text        = $parts[2]; // Remaining text after current tag.
 
 			// Check for: Auto-close tag (like <hr/>)
 			//			 Comments and Processing Instructions.
 			if (preg_match('{^</?(?:' . $this->auto_close_tags_re . ')\b}', $tag) ||
 				$tag[1] === '!' || $tag[1] === '?')
 			{
 				// Just add the tag to the block as if it was text.
 				$block_text .= $tag;
 			}
 			else {
 				// Increase/decrease nested tag count. Only do so if
 				// the tag's name match base tag's.
 				if (preg_match('{^</?' . $base_tag_name_re . '\b}', $tag)) {
 					if ($tag[1] === '/') {
 						$depth--;
 					} else if ($tag[strlen($tag)-2] !== '/') {
 						$depth++;
 					}
 				}
 
 				// Check for `markdown="1"` attribute and handle it.
 				if ($md_attr &&
 					preg_match($markdown_attr_re, $tag, $attr_m) &&
 					preg_match('/^1|block|span$/', $attr_m[2] . $attr_m[3]))
 				{
 					// Remove `markdown` attribute from opening tag.
 					$tag = preg_replace($markdown_attr_re, '', $tag);
 
 					// Check if text inside this tag must be parsed in span mode.
 					$mode = $attr_m[2] . $attr_m[3];
 					$span_mode = $mode === 'span' || ($mode !== 'block' &&
 						preg_match('{^<(?:' . $this->contain_span_tags_re . ')\b}', $tag));
 
 					// Calculate indent before tag.
 					if (preg_match('/(?:^|\n)( *?)(?! ).*?$/', $block_text, $matches)) {
 						$strlen = $this->utf8_strlen;
 						$indent = $strlen($matches[1], 'UTF-8');
 					} else {
 						$indent = 0;
 					}
 
 					// End preceding block with this tag.
 					$block_text .= $tag;
 					$parsed .= $this->$hash_method($block_text);
 
 					// Get enclosing tag name for the ParseMarkdown function.
 					// (This pattern makes $tag_name_re safe without quoting.)
 					preg_match('/^<([\w:$]*)\b/', $tag, $matches);
 					$tag_name_re = $matches[1];
 
 					// Parse the content using the HTML-in-Markdown parser.
 					list ($block_text, $text)
 						= $this->_hashHTMLBlocks_inMarkdown($text, $indent,
 							$tag_name_re, $span_mode);
 
 					// Outdent markdown text.
 					if ($indent > 0) {
 						$block_text = preg_replace("/^[ ]{1,$indent}/m", "",
 													$block_text);
 					}
 
 					// Append tag content to parsed text.
 					if (!$span_mode) {
 						$parsed .= "\n\n$block_text\n\n";
 					} else {
 						$parsed .= (string) $block_text;
 					}
 
 					// Start over with a new block.
 					$block_text = "";
 				}
 				else $block_text .= $tag;
 			}
 
 		} while ($depth > 0);
 
 		// Hash last block text that wasn't processed inside the loop.
 		$parsed .= $this->$hash_method($block_text);
 
 		return array($parsed, $text);
 	}
 
 	/**
 	 * Called whenever a tag must be hashed when a function inserts a "clean" tag
 	 * in $text, it passes through this function and is automaticaly escaped,
 	 * blocking invalid nested overlap.
 	 * @param  string $text
 	 * @return string
 	 */
 	protected function hashClean($text) {
 		return $this->hashPart($text, 'C');
 	}
 
 	/**
 	 * Turn Markdown link shortcuts into XHTML <a> tags.
 	 * @param  string $text
 	 * @return string
 	 */
 	protected function doAnchors($text) {
 		if ($this->in_anchor) {
 			return $text;
 		}
 		$this->in_anchor = true;
 
 		// First, handle reference-style links: [link text] [id]
 		$text = preg_replace_callback('{
 			(					# wrap whole match in $1
 			  \[
 				(' . $this->nested_brackets_re . ')	# link text = $2
 			  \]
 
 			  [ ]?				# one optional space
 			  (?:\n[ ]*)?		# one optional newline followed by spaces
 
 			  \[
 				(.*?)		# id = $3
 			  \]
 			)
 			}xs',
 			array($this, '_doAnchors_reference_callback'), $text);
 
 		// Next, inline-style links: [link text](url "optional title")
 		$text = preg_replace_callback('{
 			(				# wrap whole match in $1
 			  \[
 				(' . $this->nested_brackets_re . ')	# link text = $2
 			  \]
 			  \(			# literal paren
 				[ \n]*
 				(?:
 					<(.+?)>	# href = $3
 				|
 					(' . $this->nested_url_parenthesis_re . ')	# href = $4
 				)
 				[ \n]*
 				(			# $5
 				  ([\'"])	# quote char = $6
 				  (.*?)		# Title = $7
 				  \6		# matching quote
 				  [ \n]*	# ignore any spaces/tabs between closing quote and )
 				)?			# title is optional
 			  \)
 			  (?:[ ]? ' . $this->id_class_attr_catch_re . ' )?	 # $8 = id/class attributes
 			)
 			}xs',
 			array($this, '_doAnchors_inline_callback'), $text);
 
 		// Last, handle reference-style shortcuts: [link text]
 		// These must come last in case you've also got [link text][1]
 		// or [link text](/foo)
 		$text = preg_replace_callback('{
 			(					# wrap whole match in $1
 			  \[
 				([^\[\]]+)		# link text = $2; can\'t contain [ or ]
 			  \]
 			)
 			}xs',
 			array($this, '_doAnchors_reference_callback'), $text);
 
 		$this->in_anchor = false;
 		return $text;
 	}
 
 	/**
 	 * Callback for reference anchors
 	 * @param  array $matches
 	 * @return string
 	 */
 	protected function _doAnchors_reference_callback($matches) {
 		$whole_match =  $matches[1];
 		$link_text   =  $matches[2];
 		$link_id     =& $matches[3];
 
 		if ($link_id == "") {
 			// for shortcut links like [this][] or [this].
 			$link_id = $link_text;
 		}
 
 		// lower-case and turn embedded newlines into spaces
 		$link_id = strtolower($link_id);
 		$link_id = preg_replace('{[ ]?\n}', ' ', $link_id);
 
 		if (isset($this->urls[$link_id])) {
 			$url = $this->urls[$link_id];
 			$url = $this->encodeURLAttribute($url);
 
 			$result = "<a href=\"$url\"";
 			if ( isset( $this->titles[$link_id] ) ) {
 				$title = $this->titles[$link_id];
 				$title = $this->encodeAttribute($title);
 				$result .=  " title=\"$title\"";
 			}
 			if (isset($this->ref_attr[$link_id]))
 				$result .= $this->ref_attr[$link_id];
 
 			$link_text = $this->runSpanGamut($link_text);
 			$result .= ">$link_text</a>";
 			$result = $this->hashPart($result);
 		}
 		else {
 			$result = $whole_match;
 		}
 		return $result;
 	}
 
 	/**
 	 * Callback for inline anchors
 	 * @param  array $matches
 	 * @return string
 	 */
 	protected function _doAnchors_inline_callback($matches) {
 		$link_text		=  $this->runSpanGamut($matches[2]);
 		$url			=  $matches[3] === '' ? $matches[4] : $matches[3];
 		$title_quote	=& $matches[6];
 		$title			=& $matches[7];
 		$attr  = $this->doExtraAttributes("a", $dummy =& $matches[8]);
 
 		// if the URL was of the form <s p a c e s> it got caught by the HTML
 		// tag parser and hashed. Need to reverse the process before using the URL.
 		$unhashed = $this->unhash($url);
 		if ($unhashed !== $url)
 			$url = preg_replace('/^<(.*)>$/', '\1', $unhashed);
 
 		$url = $this->encodeURLAttribute($url);
 
 		$result = "<a href=\"$url\"";
 		if (isset($title) && $title_quote) {
 			$title = $this->encodeAttribute($title);
 			$result .=  " title=\"$title\"";
 		}
 		$result .= $attr;
 
 		$link_text = $this->runSpanGamut($link_text);
 		$result .= ">$link_text</a>";
 
 		return $this->hashPart($result);
 	}
 
 	/**
 	 * Turn Markdown image shortcuts into <img> tags.
 	 * @param  string $text
 	 * @return string
 	 */
 	protected function doImages($text) {
 		// First, handle reference-style labeled images: ![alt text][id]
 		$text = preg_replace_callback('{
 			(				# wrap whole match in $1
 			  !\[
 				(' . $this->nested_brackets_re . ')		# alt text = $2
 			  \]
 
 			  [ ]?				# one optional space
 			  (?:\n[ ]*)?		# one optional newline followed by spaces
 
 			  \[
 				(.*?)		# id = $3
 			  \]
 
 			)
 			}xs',
 			array($this, '_doImages_reference_callback'), $text);
 
 		// Next, handle inline images:  ![alt text](url "optional title")
 		// Don't forget: encode * and _
 		$text = preg_replace_callback('{
 			(				# wrap whole match in $1
 			  !\[
 				(' . $this->nested_brackets_re . ')		# alt text = $2
 			  \]
 			  \s?			# One optional whitespace character
 			  \(			# literal paren
 				[ \n]*
 				(?:
 					<(\S*)>	# src url = $3
 				|
 					(' . $this->nested_url_parenthesis_re . ')	# src url = $4
 				)
 				[ \n]*
 				(			# $5
 				  ([\'"])	# quote char = $6
 				  (.*?)		# title = $7
 				  \6		# matching quote
 				  [ \n]*
 				)?			# title is optional
 			  \)
 			  (?:[ ]? ' . $this->id_class_attr_catch_re . ' )?	 # $8 = id/class attributes
 			)
 			}xs',
 			array($this, '_doImages_inline_callback'), $text);
 
 		return $text;
 	}
 
 	/**
 	 * Callback for referenced images
 	 * @param  array $matches
 	 * @return string
 	 */
 	protected function _doImages_reference_callback($matches) {
 		$whole_match = $matches[1];
 		$alt_text    = $matches[2];
 		$link_id     = strtolower($matches[3]);
 
 		if ($link_id === "") {
 			$link_id = strtolower($alt_text); // for shortcut links like ![this][].
 		}
 
 		$alt_text = $this->encodeAttribute($alt_text);
 		if (isset($this->urls[$link_id])) {
 			$url = $this->encodeURLAttribute($this->urls[$link_id]);
 			$result = "<img src=\"$url\" alt=\"$alt_text\"";
 			if (isset($this->titles[$link_id])) {
 				$title = $this->titles[$link_id];
 				$title = $this->encodeAttribute($title);
 				$result .=  " title=\"$title\"";
 			}
 			if (isset($this->ref_attr[$link_id])) {
 				$result .= $this->ref_attr[$link_id];
 			}
 			$result .= $this->empty_element_suffix;
 			$result = $this->hashPart($result);
 		}
 		else {
 			// If there's no such link ID, leave intact:
 			$result = $whole_match;
 		}
 
 		return $result;
 	}
 
 	/**
 	 * Callback for inline images
 	 * @param  array $matches
 	 * @return string
 	 */
 	protected function _doImages_inline_callback($matches) {
 		$alt_text		= $matches[2];
 		$url			= $matches[3] === '' ? $matches[4] : $matches[3];
 		$title_quote	=& $matches[6];
 		$title			=& $matches[7];
 		$attr  = $this->doExtraAttributes("img", $dummy =& $matches[8]);
 
 		$alt_text = $this->encodeAttribute($alt_text);
 		$url = $this->encodeURLAttribute($url);
 		$result = "<img src=\"$url\" alt=\"$alt_text\"";
 		if (isset($title) && $title_quote) {
 			$title = $this->encodeAttribute($title);
 			$result .=  " title=\"$title\""; // $title already quoted
 		}
 		$result .= $attr;
 		$result .= $this->empty_element_suffix;
 
 		return $this->hashPart($result);
 	}
 
 	/**
 	 * Process markdown headers. Redefined to add ID and class attribute support.
 	 * @param  string $text
 	 * @return string
 	 */
 	protected function doHeaders($text) {
 		// Setext-style headers:
 		//  Header 1  {#header1}
 		//	  ========
 		//
 		//	  Header 2  {#header2 .class1 .class2}
 		//	  --------
 		//
 		$text = preg_replace_callback(
 			'{
 				(^.+?)								# $1: Header text
 				(?:[ ]+ ' . $this->id_class_attr_catch_re . ' )?	 # $3 = id/class attributes
 				[ ]*\n(=+|-+)[ ]*\n+				# $3: Header footer
 			}mx',
 			array($this, '_doHeaders_callback_setext'), $text);
 
 		// atx-style headers:
 		//	# Header 1        {#header1}
 		//	## Header 2       {#header2}
 		//	## Header 2 with closing hashes ##  {#header3.class1.class2}
 		//	...
 		//	###### Header 6   {.class2}
 		//
 		$text = preg_replace_callback('{
 				^(\#{1,6})	# $1 = string of #\'s
 				[ ]'.($this->hashtag_protection ? '+' : '*').'
 				(.+?)		# $2 = Header text
 				[ ]*
 				\#*			# optional closing #\'s (not counted)
 				(?:[ ]+ ' . $this->id_class_attr_catch_re . ' )?	 # $3 = id/class attributes
 				[ ]*
 				\n+
 			}xm',
 			array($this, '_doHeaders_callback_atx'), $text);
 
 		return $text;
 	}
 
 	/**
 	 * Callback for setext headers
 	 * @param  array $matches
 	 * @return string
 	 */
 	protected function _doHeaders_callback_setext($matches) {
 		if ($matches[3] === '-' && preg_match('{^- }', $matches[1])) {
 			return $matches[0];
 		}
 
 		$level = $matches[3][0] === '=' ? 1 : 2;
 
 		$defaultId = is_callable($this->header_id_func) ? call_user_func($this->header_id_func, $matches[1]) : null;
 
 		$attr  = $this->doExtraAttributes("h$level", $dummy =& $matches[2], $defaultId);
 		$block = "<h$level$attr>" . $this->runSpanGamut($matches[1]) . "</h$level>";
 		return "\n" . $this->hashBlock($block) . "\n\n";
 	}
 
 	/**
 	 * Callback for atx headers
 	 * @param  array $matches
 	 * @return string
 	 */
 	protected function _doHeaders_callback_atx($matches) {
 		$level = strlen($matches[1]);
 
 		$defaultId = is_callable($this->header_id_func) ? call_user_func($this->header_id_func, $matches[2]) : null;
 		$attr  = $this->doExtraAttributes("h$level", $dummy =& $matches[3], $defaultId);
 		$block = "<h$level$attr>" . $this->runSpanGamut($matches[2]) . "</h$level>";
 		return "\n" . $this->hashBlock($block) . "\n\n";
 	}
 
 	/**
 	 * Form HTML tables.
 	 * @param  string $text
 	 * @return string
 	 */
 	protected function doTables($text) {
 		$less_than_tab = $this->tab_width - 1;
 		// Find tables with leading pipe.
 		//
 		//	| Header 1 | Header 2
 		//	| -------- | --------
 		//	| Cell 1   | Cell 2
 		//	| Cell 3   | Cell 4
 		$text = preg_replace_callback('
 			{
 				^							# Start of a line
 				[ ]{0,' . $less_than_tab . '}	# Allowed whitespace.
 				[|]							# Optional leading pipe (present)
 				(.+) \n						# $1: Header row (at least one pipe)
 
 				[ ]{0,' . $less_than_tab . '}	# Allowed whitespace.
 				[|] ([ ]*[-:]+[-| :]*) \n	# $2: Header underline
 
 				(							# $3: Cells
 					(?>
 						[ ]*				# Allowed whitespace.
 						[|] .* \n			# Row content.
 					)*
 				)
 				(?=\n|\Z)					# Stop at final double newline.
 			}xm',
 			array($this, '_doTable_leadingPipe_callback'), $text);
 
 		// Find tables without leading pipe.
 		//
 		//	Header 1 | Header 2
 		//	-------- | --------
 		//	Cell 1   | Cell 2
 		//	Cell 3   | Cell 4
 		$text = preg_replace_callback('
 			{
 				^							# Start of a line
 				[ ]{0,' . $less_than_tab . '}	# Allowed whitespace.
 				(\S.*[|].*) \n				# $1: Header row (at least one pipe)
 
 				[ ]{0,' . $less_than_tab . '}	# Allowed whitespace.
 				([-:]+[ ]*[|][-| :]*) \n	# $2: Header underline
 
 				(							# $3: Cells
 					(?>
 						.* [|] .* \n		# Row content
 					)*
 				)
 				(?=\n|\Z)					# Stop at final double newline.
 			}xm',
 			array($this, '_DoTable_callback'), $text);
 
 		return $text;
 	}
 
 	/**
 	 * Callback for removing the leading pipe for each row
 	 * @param  array $matches
 	 * @return string
 	 */
 	protected function _doTable_leadingPipe_callback($matches) {
 		$head		= $matches[1];
 		$underline	= $matches[2];
 		$content	= $matches[3];
 
 		$content	= preg_replace('/^ *[|]/m', '', $content);
 
 		return $this->_doTable_callback(array($matches[0], $head, $underline, $content));
 	}
 
 	/**
 	 * Make the align attribute in a table
 	 * @param  string $alignname
 	 * @return string
 	 */
 	protected function _doTable_makeAlignAttr($alignname) {
 		if (empty($this->table_align_class_tmpl)) {
 			return " align=\"$alignname\"";
 		}
 
 		$classname = str_replace('%%', $alignname, $this->table_align_class_tmpl);
 		return " class=\"$classname\"";
 	}
 
 	/**
 	 * Calback for processing tables
 	 * @param  array $matches
 	 * @return string
 	 */
 	protected function _doTable_callback($matches) {
 		$head		= $matches[1];
 		$underline	= $matches[2];
 		$content	= $matches[3];
 
 		// Remove any tailing pipes for each line.
 		$head		= preg_replace('/[|] *$/m', '', $head);
 		$underline	= preg_replace('/[|] *$/m', '', $underline);
 		$content	= preg_replace('/[|] *$/m', '', $content);
 
 		// Reading alignement from header underline.
 		$separators	= preg_split('/ *[|] */', $underline);
 		foreach ($separators as $n => $s) {
 			if (preg_match('/^ *-+: *$/', $s))
 				$attr[$n] = $this->_doTable_makeAlignAttr('right');
 			else if (preg_match('/^ *:-+: *$/', $s))
 				$attr[$n] = $this->_doTable_makeAlignAttr('center');
 			else if (preg_match('/^ *:-+ *$/', $s))
 				$attr[$n] = $this->_doTable_makeAlignAttr('left');
 			else
 				$attr[$n] = '';
 		}
 
 		// Parsing span elements, including code spans, character escapes,
 		// and inline HTML tags, so that pipes inside those gets ignored.
 		$head		= $this->parseSpan($head);
 		$headers	= preg_split('/ *[|] */', $head);
 		$col_count	= count($headers);
 		$attr       = array_pad($attr, $col_count, '');
 
 		// Write column headers.
 		$text = "<table>\n";
 		$text .= "<thead>\n";
 		$text .= "<tr>\n";
 		foreach ($headers as $n => $header) {
 			$text .= "  <th$attr[$n]>" . $this->runSpanGamut(trim($header)) . "</th>\n";
 		}
 		$text .= "</tr>\n";
 		$text .= "</thead>\n";
 
 		// Split content by row.
 		$rows = explode("\n", trim($content, "\n"));
 
 		$text .= "<tbody>\n";
 		foreach ($rows as $row) {
 			// Parsing span elements, including code spans, character escapes,
 			// and inline HTML tags, so that pipes inside those gets ignored.
 			$row = $this->parseSpan($row);
 
 			// Split row by cell.
 			$row_cells = preg_split('/ *[|] */', $row, $col_count);
 			$row_cells = array_pad($row_cells, $col_count, '');
 
 			$text .= "<tr>\n";
 			foreach ($row_cells as $n => $cell) {
 				$text .= "  <td$attr[$n]>" . $this->runSpanGamut(trim($cell)) . "</td>\n";
 			}
 			$text .= "</tr>\n";
 		}
 		$text .= "</tbody>\n";
 		$text .= "</table>";
 
 		return $this->hashBlock($text) . "\n";
 	}
 
 	/**
 	 * Form HTML definition lists.
 	 * @param  string $text
 	 * @return string
 	 */
 	protected function doDefLists($text) {
 		$less_than_tab = $this->tab_width - 1;
 
 		// Re-usable pattern to match any entire dl list:
 		$whole_list_re = '(?>
 			(								# $1 = whole list
 			  (								# $2
 				[ ]{0,' . $less_than_tab . '}
 				((?>.*\S.*\n)+)				# $3 = defined term
 				\n?
 				[ ]{0,' . $less_than_tab . '}:[ ]+ # colon starting definition
 			  )
 			  (?s:.+?)
 			  (								# $4
 				  \z
 				|
 				  \n{2,}
 				  (?=\S)
 				  (?!						# Negative lookahead for another term
 					[ ]{0,' . $less_than_tab . '}
 					(?: \S.*\n )+?			# defined term
 					\n?
 					[ ]{0,' . $less_than_tab . '}:[ ]+ # colon starting definition
 				  )
 				  (?!						# Negative lookahead for another definition
 					[ ]{0,' . $less_than_tab . '}:[ ]+ # colon starting definition
 				  )
 			  )
 			)
 		)'; // mx
 
 		$text = preg_replace_callback('{
 				(?>\A\n?|(?<=\n\n))
 				' . $whole_list_re . '
 			}mx',
 			array($this, '_doDefLists_callback'), $text);
 
 		return $text;
 	}
 
 	/**
 	 * Callback for processing definition lists
 	 * @param  array $matches
 	 * @return string
 	 */
 	protected function _doDefLists_callback($matches) {
 		// Re-usable patterns to match list item bullets and number markers:
 		$list = $matches[1];
 
 		// Turn double returns into triple returns, so that we can make a
 		// paragraph for the last item in a list, if necessary:
 		$result = trim($this->processDefListItems($list));
 		$result = "<dl>\n" . $result . "\n</dl>";
 		return $this->hashBlock($result) . "\n\n";
 	}
 
 	/**
 	 * Process the contents of a single definition list, splitting it
 	 * into individual term and definition list items.
 	 * @param  string $list_str
 	 * @return string
 	 */
 	protected function processDefListItems($list_str) {
 
 		$less_than_tab = $this->tab_width - 1;
 
 		// Trim trailing blank lines:
 		$list_str = preg_replace("/\n{2,}\\z/", "\n", $list_str);
 
 		// Process definition terms.
 		$list_str = preg_replace_callback('{
 			(?>\A\n?|\n\n+)						# leading line
 			(									# definition terms = $1
 				[ ]{0,' . $less_than_tab . '}	# leading whitespace
 				(?!\:[ ]|[ ])					# negative lookahead for a definition
 												#   mark (colon) or more whitespace.
 				(?> \S.* \n)+?					# actual term (not whitespace).
 			)
 			(?=\n?[ ]{0,3}:[ ])					# lookahead for following line feed
 												#   with a definition mark.
 			}xm',
 			array($this, '_processDefListItems_callback_dt'), $list_str);
 
 		// Process actual definitions.
 		$list_str = preg_replace_callback('{
 			\n(\n+)?							# leading line = $1
 			(									# marker space = $2
 				[ ]{0,' . $less_than_tab . '}	# whitespace before colon
 				\:[ ]+							# definition mark (colon)
 			)
 			((?s:.+?))							# definition text = $3
 			(?= \n+ 							# stop at next definition mark,
 				(?:								# next term or end of text
 					[ ]{0,' . $less_than_tab . '} \:[ ]	|
 					<dt> | \z
 				)
 			)
 			}xm',
 			array($this, '_processDefListItems_callback_dd'), $list_str);
 
 		return $list_str;
 	}
 
 	/**
 	 * Callback for <dt> elements in definition lists
 	 * @param  array $matches
 	 * @return string
 	 */
 	protected function _processDefListItems_callback_dt($matches) {
 		$terms = explode("\n", trim($matches[1]));
 		$text = '';
 		foreach ($terms as $term) {
 			$term = $this->runSpanGamut(trim($term));
 			$text .= "\n<dt>" . $term . "</dt>";
 		}
 		return $text . "\n";
 	}
 
 	/**
 	 * Callback for <dd> elements in definition lists
 	 * @param  array $matches
 	 * @return string
 	 */
 	protected function _processDefListItems_callback_dd($matches) {
 		$leading_line	= $matches[1];
 		$marker_space	= $matches[2];
 		$def			= $matches[3];
 
 		if ($leading_line || preg_match('/\n{2,}/', $def)) {
 			// Replace marker with the appropriate whitespace indentation
 			$def = str_repeat(' ', strlen($marker_space)) . $def;
 			$def = $this->runBlockGamut($this->outdent($def . "\n\n"));
 			$def = "\n". $def ."\n";
 		}
 		else {
 			$def = rtrim($def);
 			$def = $this->runSpanGamut($this->outdent($def));
 		}
 
 		return "\n<dd>" . $def . "</dd>\n";
 	}
 
 	/**
 	 * Adding the fenced code block syntax to regular Markdown:
 	 *
 	 * ~~~
 	 * Code block
 	 * ~~~
 	 *
 	 * @param  string $text
 	 * @return string
 	 */
 	protected function doFencedCodeBlocks($text) {
 
 		$text = preg_replace_callback('{
 				(?:\n|\A)
 				# 1: Opening marker
 				(
 					(?:~{3,}|`{3,}) # 3 or more tildes/backticks.
 				)
 				[ ]*
 				(?:
 					\.?([-_:a-zA-Z0-9]+) # 2: standalone class name
 				)?
 				[ ]*
 				(?:
 					' . $this->id_class_attr_catch_re . ' # 3: Extra attributes
 				)?
 				[ ]* \n # Whitespace and newline following marker.
 
 				# 4: Content
 				(
 					(?>
 						(?!\1 [ ]* \n)	# Not a closing marker.
 						.*\n+
 					)+
 				)
 
 				# Closing marker.
 				\1 [ ]* (?= \n )
 			}xm',
 			array($this, '_doFencedCodeBlocks_callback'), $text);
 
 		return $text;
 	}
 
 	/**
 	 * Callback to process fenced code blocks
 	 * @param  array $matches
 	 * @return string
 	 */
 	protected function _doFencedCodeBlocks_callback($matches) {
 		$classname =& $matches[2];
 		$attrs     =& $matches[3];
 		$codeblock = $matches[4];
 
 		if ($this->code_block_content_func) {
 			$codeblock = call_user_func($this->code_block_content_func, $codeblock, $classname);
 		} else {
 			$codeblock = htmlspecialchars($codeblock, ENT_NOQUOTES);
 		}
 
 		$codeblock = preg_replace_callback('/^\n+/',
 			array($this, '_doFencedCodeBlocks_newlines'), $codeblock);
 
 		$classes = array();
 		if ($classname !== "") {
 			if ($classname[0] === '.') {
 				$classname = substr($classname, 1);
 			}
 			$classes[] = $this->code_class_prefix . $classname;
 		}
 		$attr_str = $this->doExtraAttributes($this->code_attr_on_pre ? "pre" : "code", $attrs, null, $classes);
 		$pre_attr_str  = $this->code_attr_on_pre ? $attr_str : '';
 		$code_attr_str = $this->code_attr_on_pre ? '' : $attr_str;
 		$codeblock  = "<pre$pre_attr_str><code$code_attr_str>$codeblock</code></pre>";
 
 		return "\n\n".$this->hashBlock($codeblock)."\n\n";
 	}
 
 	/**
 	 * Replace new lines in fenced code blocks
 	 * @param  array $matches
 	 * @return string
 	 */
 	protected function _doFencedCodeBlocks_newlines($matches) {
 		return str_repeat("<br$this->empty_element_suffix",
 			strlen($matches[0]));
 	}
 
 	/**
 	 * Redefining emphasis markers so that emphasis by underscore does not
 	 * work in the middle of a word.
 	 * @var array
 	 */
 	protected $em_relist = array(
 		''  => '(?:(?<!\*)\*(?!\*)|(?<![a-zA-Z0-9_])_(?!_))(?![\.,:;]?\s)',
 		'*' => '(?<![\s*])\*(?!\*)',
 		'_' => '(?<![\s_])_(?![a-zA-Z0-9_])',
 	);
 	protected $strong_relist = array(
 		''   => '(?:(?<!\*)\*\*(?!\*)|(?<![a-zA-Z0-9_])__(?!_))(?![\.,:;]?\s)',
 		'**' => '(?<![\s*])\*\*(?!\*)',
 		'__' => '(?<![\s_])__(?![a-zA-Z0-9_])',
 	);
 	protected $em_strong_relist = array(
 		''    => '(?:(?<!\*)\*\*\*(?!\*)|(?<![a-zA-Z0-9_])___(?!_))(?![\.,:;]?\s)',
 		'***' => '(?<![\s*])\*\*\*(?!\*)',
 		'___' => '(?<![\s_])___(?![a-zA-Z0-9_])',
 	);
 
 	/**
 	 * Parse text into paragraphs
 	 * @param  string $text String to process in paragraphs
 	 * @param  boolean $wrap_in_p Whether paragraphs should be wrapped in <p> tags
 	 * @return string       HTML output
 	 */
 	protected function formParagraphs($text, $wrap_in_p = true) {
 		// Strip leading and trailing lines:
 		$text = preg_replace('/\A\n+|\n+\z/', '', $text);
 
 		$grafs = preg_split('/\n{2,}/', $text, -1, PREG_SPLIT_NO_EMPTY);
 
 		// Wrap <p> tags and unhashify HTML blocks
 		foreach ($grafs as $key => $value) {
 			$value = trim($this->runSpanGamut($value));
 
 			// Check if this should be enclosed in a paragraph.
 			// Clean tag hashes & block tag hashes are left alone.
 			$is_p = $wrap_in_p && !preg_match('/^B\x1A[0-9]+B|^C\x1A[0-9]+C$/', $value);
 
 			if ($is_p) {
 				$value = "<p>$value</p>";
 			}
 			$grafs[$key] = $value;
 		}
 
 		// Join grafs in one text, then unhash HTML tags.
 		$text = implode("\n\n", $grafs);
 
 		// Finish by removing any tag hashes still present in $text.
 		$text = $this->unhash($text);
 
 		return $text;
 	}
 
 
 	/**
 	 * Footnotes - Strips link definitions from text, stores the URLs and
 	 * titles in hash references.
 	 * @param  string $text
 	 * @return string
 	 */
 	protected function stripFootnotes($text) {
 		$less_than_tab = $this->tab_width - 1;
 
 		// Link defs are in the form: [^id]: url "optional title"
 		$text = preg_replace_callback('{
 			^[ ]{0,' . $less_than_tab . '}\[\^(.+?)\][ ]?:	# note_id = $1
 			  [ ]*
 			  \n?					# maybe *one* newline
 			(						# text = $2 (no blank lines allowed)
 				(?:
 					.+				# actual text
 				|
 					\n				# newlines but
 					(?!\[.+?\][ ]?:\s)# negative lookahead for footnote or link definition marker.
 					(?!\n+[ ]{0,3}\S)# ensure line is not blank and followed
 									# by non-indented content
 				)*
 			)
 			}xm',
 			array($this, '_stripFootnotes_callback'),
 			$text);
 		return $text;
 	}
 
 	/**
 	 * Callback for stripping footnotes
 	 * @param  array $matches
 	 * @return string
 	 */
 	protected function _stripFootnotes_callback($matches) {
 		$note_id = $this->fn_id_prefix . $matches[1];
 		$this->footnotes[$note_id] = $this->outdent($matches[2]);
 		return ''; // String that will replace the block
 	}
 
 	/**
 	 * Replace footnote references in $text [^id] with a special text-token
 	 * which will be replaced by the actual footnote marker in appendFootnotes.
 	 * @param  string $text
 	 * @return string
 	 */
 	protected function doFootnotes($text) {
 		if (!$this->in_anchor) {
 			$text = preg_replace('{\[\^(.+?)\]}', "F\x1Afn:\\1\x1A:", $text);
 		}
 		return $text;
 	}
 
 	/**
 	 * Append footnote list to text
 	 * @param  string $text
 	 * @return string
 	 */
 	protected function appendFootnotes($text) {
 		$text = preg_replace_callback('{F\x1Afn:(.*?)\x1A:}',
 			array($this, '_appendFootnotes_callback'), $text);
 
 		if ( ! empty( $this->footnotes_ordered ) ) {
 			$this->_doFootnotes();
 			if ( ! $this->omit_footnotes ) {
 				$text .= "\n\n";
 				$text .= "<div class=\"footnotes\" role=\"doc-endnotes\">\n";
 				$text .= "<hr" . $this->empty_element_suffix . "\n";
 				$text .= $this->footnotes_assembled;
 				$text .= "</div>";
 			}
 		}
 		return $text;
 	}
 
 
 	/**
 	 * Generates the HTML for footnotes.  Called by appendFootnotes, even if
 	 * footnotes are not being appended.
 	 * @return void
 	 */
 	protected function _doFootnotes() {
 		$attr = array();
 		if ($this->fn_backlink_class !== "") {
 			$class = $this->fn_backlink_class;
 			$class = $this->encodeAttribute($class);
 			$attr['class'] = " class=\"$class\"";
 		}
 		$attr['role'] = " role=\"doc-backlink\"";
 		$num = 0;
 
 		$text = "<ol>\n\n";
 		while (!empty($this->footnotes_ordered)) {
 			$footnote = reset($this->footnotes_ordered);
 			$note_id = key($this->footnotes_ordered);
 			unset($this->footnotes_ordered[$note_id]);
 			$ref_count = $this->footnotes_ref_count[$note_id];
 			unset($this->footnotes_ref_count[$note_id]);
 			unset($this->footnotes[$note_id]);
 
 			$footnote .= "\n"; // Need to append newline before parsing.
 			$footnote = $this->runBlockGamut("$footnote\n");
 			$footnote = preg_replace_callback('{F\x1Afn:(.*?)\x1A:}',
 				array($this, '_appendFootnotes_callback'), $footnote);
 
 			$num++;
 			$note_id = $this->encodeAttribute($note_id);
 
 			// Prepare backlink, multiple backlinks if multiple references
 			// Do not create empty backlinks if the html is blank
 			$backlink = "";
 			if (!empty($this->fn_backlink_html)) {
 				for ($ref_num = 1; $ref_num <= $ref_count; ++$ref_num) {
 					if (!empty($this->fn_backlink_title)) {
 						$attr['title'] = ' title="' . $this->encodeAttribute($this->fn_backlink_title) . '"';
 					}
 					if (!empty($this->fn_backlink_label)) {
 						$attr['label'] = ' aria-label="' . $this->encodeAttribute($this->fn_backlink_label) . '"';
 					}
 					$parsed_attr = $this->parseFootnotePlaceholders(
 						implode('', $attr),
 						$num,
 						$ref_num
 					);
 					$backlink_text = $this->parseFootnotePlaceholders(
 						$this->fn_backlink_html,
 						$num,
 						$ref_num
 					);
 					$ref_count_mark = $ref_num > 1 ? $ref_num : '';
 					$backlink .= " <a href=\"#fnref$ref_count_mark:$note_id\"$parsed_attr>$backlink_text</a>";
 				}
 				$backlink = trim($backlink);
 			}
 
 			// Add backlink to last paragraph; create new paragraph if needed.
 			if (!empty($backlink)) {
 				if (preg_match('{</p>$}', $footnote)) {
 					$footnote = substr($footnote, 0, -4) . "&#160;$backlink</p>";
 				} else {
 					$footnote .= "\n\n<p>$backlink</p>";
 				}
 			}
 
 			$text .= "<li id=\"fn:$note_id\" role=\"doc-endnote\">\n";
 			$text .= $footnote . "\n";
 			$text .= "</li>\n\n";
 		}
 		$text .= "</ol>\n";
 
 		$this->footnotes_assembled = $text;
 	}
 
 	/**
 	 * Callback for appending footnotes
 	 * @param  array $matches
 	 * @return string
 	 */
 	protected function _appendFootnotes_callback($matches) {
 		$node_id = $this->fn_id_prefix . $matches[1];
 
 		// Create footnote marker only if it has a corresponding footnote *and*
 		// the footnote hasn't been used by another marker.
 		if (isset($this->footnotes[$node_id])) {
 			$num =& $this->footnotes_numbers[$node_id];
 			if (!isset($num)) {
 				// Transfer footnote content to the ordered list and give it its
 				// number
 				$this->footnotes_ordered[$node_id] = $this->footnotes[$node_id];
 				$this->footnotes_ref_count[$node_id] = 1;
 				$num = $this->footnote_counter++;
 				$ref_count_mark = '';
 			} else {
 				$ref_count_mark = $this->footnotes_ref_count[$node_id] += 1;
 			}
 
 			$attr = "";
 			if ($this->fn_link_class !== "") {
 				$class = $this->fn_link_class;
 				$class = $this->encodeAttribute($class);
 				$attr .= " class=\"$class\"";
 			}
 			if ($this->fn_link_title !== "") {
 				$title = $this->fn_link_title;
 				$title = $this->encodeAttribute($title);
 				$attr .= " title=\"$title\"";
 			}
 			$attr .= " role=\"doc-noteref\"";
 
 			$attr = str_replace("%%", $num, $attr);
 			$node_id = $this->encodeAttribute($node_id);
 
 			return
 				"<sup id=\"fnref$ref_count_mark:$node_id\">".
 				"<a href=\"#fn:$node_id\"$attr>$num</a>".
 				"</sup>";
 		}
 
 		return "[^" . $matches[1] . "]";
 	}
 
 	/**
 	 * Build footnote label by evaluating any placeholders.
 	 * - ^^  footnote number
 	 * - %%  footnote reference number (Nth reference to footnote number)
 	 * @param  string $label
 	 * @param  int    $footnote_number
 	 * @param  int    $reference_number
 	 * @return string
 	 */
 	protected function parseFootnotePlaceholders($label, $footnote_number, $reference_number) {
 		return str_replace(
 			array('^^', '%%'),
 			array($footnote_number, $reference_number),
 			$label
 		);
 	}
 
 
 	/**
 	 * Abbreviations - strips abbreviations from text, stores titles in hash
 	 * references.
 	 * @param  string $text
 	 * @return string
 	 */
 	protected function stripAbbreviations($text) {
 		$less_than_tab = $this->tab_width - 1;
 
 		// Link defs are in the form: [id]*: url "optional title"
 		$text = preg_replace_callback('{
 			^[ ]{0,' . $less_than_tab . '}\*\[(.+?)\][ ]?:	# abbr_id = $1
 			(.*)					# text = $2 (no blank lines allowed)
 			}xm',
 			array($this, '_stripAbbreviations_callback'),
 			$text);
 		return $text;
 	}
 
 	/**
 	 * Callback for stripping abbreviations
 	 * @param  array $matches
 	 * @return string
 	 */
 	protected function _stripAbbreviations_callback($matches) {
 		$abbr_word = $matches[1];
 		$abbr_desc = $matches[2];
 		if ($this->abbr_word_re) {
 			$this->abbr_word_re .= '|';
 		}
 		$this->abbr_word_re .= preg_quote($abbr_word);
 		$this->abbr_desciptions[$abbr_word] = trim($abbr_desc);
 		return ''; // String that will replace the block
 	}
 
 	/**
 	 * Find defined abbreviations in text and wrap them in <abbr> elements.
 	 * @param  string $text
 	 * @return string
 	 */
 	protected function doAbbreviations($text) {
 		if ($this->abbr_word_re) {
 			// cannot use the /x modifier because abbr_word_re may
 			// contain significant spaces:
 			$text = preg_replace_callback('{' .
 				'(?<![\w\x1A])' .
 				'(?:' . $this->abbr_word_re . ')' .
 				'(?![\w\x1A])' .
 				'}',
 				array($this, '_doAbbreviations_callback'), $text);
 		}
 		return $text;
 	}
 
 	/**
 	 * Callback for processing abbreviations
 	 * @param  array $matches
 	 * @return string
 	 */
 	protected function _doAbbreviations_callback($matches) {
 		$abbr = $matches[0];
 		if (isset($this->abbr_desciptions[$abbr])) {
 			$desc = $this->abbr_desciptions[$abbr];
 			if (empty($desc)) {
 				return $this->hashPart("<abbr>$abbr</abbr>");
 			}
 			$desc = $this->encodeAttribute($desc);
 			return $this->hashPart("<abbr title=\"$desc\">$abbr</abbr>");
 		}
 		return $matches[0];
 	}
 }
 
 // Markdown parser, Copyright Datenstrom, License GPLv2
 
 class YellowMarkdownParser extends MarkdownExtraParser {
     public $yellow;             // access to API
     public $page;               // access to page
     public $idAttributes;       // id attributes
 
     public function __construct($yellow, $page) {
         $this->yellow = $yellow;
         $this->page = $page;
         $this->idAttributes = array();
         $this->url_filter_func = function($url) use ($yellow, $page) {
             return $yellow->lookup->normaliseLocation($url, $page->getPage("main")->location);
         };
         $this->span_gamut += array("doStrikethrough" => 55);
         $this->block_gamut += array("doCollapsibleBlocks" => 65);
         $this->block_gamut += array("doGeneralBlocks" => 75);
         $this->document_gamut += array("doFootnotesLinks" => 55);
         $this->escape_chars .= "~?";
         parent::__construct();
     }
 
     // Handle striketrough
     public function doStrikethrough($text) {
         $parts = preg_split("/(?<![~])(~~)(?![~])/", $text, -1, PREG_SPLIT_DELIM_CAPTURE);
         if (count($parts)>3) {
             $text = "";
             $open = false;
             foreach ($parts as $part) {
                 if ($part=="~~") {
                     $text .= $open ? "</del>" : "<del>";
                     $open = !$open;
                 } else {
                     $text .= $part;
                 }
             }
             if ($open) $text .= "</del>";
         }
         return $text;
     }
 
     // Handle links
     public function doAutoLinks($text) {
         $text = preg_replace_callback("/<(\w+:[^\'\">\s]+)>/", array($this, "_doAutoLinks_url_callback"), $text);
         $text = preg_replace_callback("/<([\w\+\-\.]+@[\w\-\.]+)>/", array($this, "_doAutoLinks_email_callback"), $text);
         $text = preg_replace_callback("/^\s*\[(\w+)([^\]]*)\]\s*$/", array($this, "_doAutoLinks_shortcutBlock_callback"), $text);
         $text = preg_replace_callback("/\[(\w+)(.*?)\]/", array($this, "_doAutoLinks_shortcutInline_callback"), $text);
         $text = preg_replace_callback("/\[\-\-(.*?)\-\-\]/", array($this, "_doAutoLinks_shortcutComment_callback"), $text);
         $text = preg_replace_callback("/\:([\w\+\-\_]+)\:/", array($this, "_doAutoLinks_shortcutSymbol_callback"), $text);
         $text = preg_replace_callback("/((http|https|ftp):\/\/\S+[^\'\"\,\.\;\:\*\~\s]+)/", array($this, "_doAutoLinks_url_callback"), $text);
         $text = preg_replace_callback("/([\w\+\-\.]+@[\w\-\.]+\.[\w]+)/", array($this, "_doAutoLinks_email_callback"), $text);
         return $text;
     }
     
     // Handle shortcuts, block style
     public function _doAutoLinks_shortcutBlock_callback($matches) {
         $output = $this->page->parseContentElement($matches[1], trim($matches[2]), "", "block");
         return is_null($output) ? $matches[0] : $this->hashBlock($output);
     }
     
     // Handle shortcuts, inline style
     public function _doAutoLinks_shortcutInline_callback($matches) {
         $output = $this->page->parseContentElement($matches[1], trim($matches[2]), "", "inline");
         return is_null($output) ? $matches[0] : $this->hashPart($output);
     }
     
     // Handle shortcuts, comment style
     public function _doAutoLinks_shortcutComment_callback($matches) {
         $output = "<!--".htmlspecialchars($matches[1], ENT_NOQUOTES)."-->";
         return $this->hashBlock($output);
     }
     
     // Handle shortcuts, symbol style
     public function _doAutoLinks_shortcutSymbol_callback($matches) {
         $output = $this->page->parseContentElement("", $matches[1], "", "symbol");
         return is_null($output) ? $matches[0] : $this->hashPart($output);
     }
     
     // Handle fenced code blocks
     public function _doFencedCodeBlocks_callback($matches) {
         $name = $this->getBlockName($matches[2], $matches[3]);
         $text = $matches[4];
         $attributes = $matches[3];
         $output = $this->page->parseContentElement($name, $text, $attributes, "code");
         if (is_null($output)) {
             $attr = $this->doExtraAttributes("pre", ".$matches[2] $matches[3]");
             $output = "<pre$attr><code>".htmlspecialchars($text, ENT_NOQUOTES)."</code></pre>";
         }
         return "\n\n".$this->hashBlock($output)."\n\n";
     }
     
     // Handle headers, text style
     public function _doHeaders_callback_setext($matches) {
         if ($matches[3]=="-" && preg_match('{^- }', $matches[1])) return $matches[0];
         $text = $matches[1];
         $level = $matches[3][0]=="=" ? 1 : 2;
         $attr = $this->doExtraAttributes("h$level", $dummy =& $matches[2]);
         if (is_string_empty($attr) && $level>=2) $attr = $this->getIdAttribute($text);
         $output = "<h$level$attr>".$this->runSpanGamut($text)."</h$level>";
         return "\n".$this->hashBlock($output)."\n\n";
     }
     
     // Handle headers, atx style
     public function _doHeaders_callback_atx($matches) {
         $text = $matches[2];
         $level = strlen($matches[1]);
         $attr = $this->doExtraAttributes("h$level", $dummy =& $matches[3]);
         if (is_string_empty($attr) && $level>=2) $attr = $this->getIdAttribute($text);
         $output = "<h$level$attr>".$this->runSpanGamut($text)."</h$level>";
         return "\n".$this->hashBlock($output)."\n\n";
     }
     
     // Handle inline links
     public function _doAnchors_inline_callback($matches) {
         $url = $matches[3]=="" ? $matches[4] : $matches[3];
         $text = $matches[2];
         $title = isset($matches[7]) ? $matches[7] : "";
         $attr = $this->doExtraAttributes("a", $dummy =& $matches[8]);
         $output = "<a href=\"".$this->encodeURLAttribute($url)."\"";
         if (!is_string_empty($title)) $output .= " title=\"".$this->encodeAttribute($title)."\"";
         $output .= $attr;
         $output .= ">".$this->runSpanGamut($text)."</a>";
         return $this->hashPart($output);
     }
     
     // Handle inline images
     public function _doImages_inline_callback($matches) {
         $src = $matches[3]=="" ? $matches[4] : $matches[3];
         if (!preg_match("/^\w+:/", $src)) {
             $src = $this->yellow->system->get("coreServerBase").$this->yellow->system->get("coreImageLocation").$src;
         }
         $alt = $matches[2];
         $title = isset($matches[7]) ? $matches[7] : $matches[2];
         $attr = $this->doExtraAttributes("img", $dummy =& $matches[8]);
         $output = "<img src=\"".$this->encodeURLAttribute($src)."\"";
         if (!is_string_empty($alt)) $output .= " alt=\"".$this->encodeAttribute($alt)."\"";
         if (!is_string_empty($title)) $output .= " title=\"".$this->encodeAttribute($title)."\"";
         $output .= $attr;
         $output .= $this->empty_element_suffix;
         return $this->hashPart($output);
     }
     
     // Handle lists, task list
     public function _processListItems_callback($matches) {
         $attr = "";
         $item = $matches[4];
         $leadingLine = $matches[1];
         $tailingLine = $matches[5];
         if ($leadingLine || $tailingLine || preg_match('/\n{2,}/', $item))
         {
             $item = $matches[2].str_repeat(' ', strlen($matches[3])).$item;
             $item = $this->runBlockGamut($this->outdent($item)."\n");
         } else {
             $item = $this->doLists($this->outdent($item));
             $item = $this->formParagraphs($item, false);
             $token = substr($item, 0, 4);
             if ($token=="[ ] " || $token=="[x] ") {
                 $attr = " class=\"task-list-item\"";
                 $item = ($token=='[ ] ' ? "<input type=\"checkbox\" disabled=\"disabled\" /> " :
                     "<input type=\"checkbox\" disabled=\"disabled\" checked=\"checked\" /> ").substr($item, 4);
             }
         }
         return "<li$attr>".$item."</li>\n";
     }
     
     // Handle blockquotes, CommonMark compatible
     public function doBlockQuotes($text) {
         return preg_replace_callback("/((?>^[ ]*>[ ]?.+\n(.+\n)*)+)/m", array($this, "_doBlockQuotes_callback"), $text);
     }
     
     // Handle collapsible block elements
     public function doCollapsibleBlocks($text) {
         return preg_replace_callback("/((?>^[ ]*\?[ ]?.+\n(.+\n)*)+)/m", array($this, "_doCollapsibleBlocks_callback"), $text);
     }
     
     // Handle collapsible block elements over multiple lines
     public function _doCollapsibleBlocks_callback($matches) {
         $name = $attributes = $attr = "";
         $text = preg_replace("/^[ ]*\?[ ]?/m", "", $matches[1]);
         if (preg_match("/^[ ]*".$this->id_class_attr_catch_re."[ ]*\n([\S\s]*)$/m", $text, $parts)) {
             $name = $this->getBlockName("", $parts[1]);
             $text = $parts[2];
             $attributes = $parts[1];
             $attr = $this->doExtraAttributes("details", $parts[1]);
         }
         if (!is_string_empty($text)) {
             $output = $this->page->parseContentElement($name, $text, $attributes, "collapsible");
             if (is_null($output)) {
                 $summary = "";
                 if (preg_match("/^(.*?)\n\n(.*)$/s", $text, $parts)) {
                     $summary = $parts[1];
                     $text = $parts[2];
                 }
                 $output = "<details$attr>\n";
                 if (!is_string_empty($summary)) $output .= "<summary>".$this->runSpanGamut($summary)."</summary>\n";
                 $output .= $this->runBlockGamut($text)."\n</details>";
             }
         } else {
             $output = "<details$attr></details>";
         }
         return "\n".$this->hashBlock($output)."\n\n";
     }
     
     // Handle general block elements
     public function doGeneralBlocks($text) {
         return preg_replace_callback("/((?>^[ ]*!(?!\[)[ ]?.+\n(.+\n)*)+)/m", array($this, "_doGeneralBlocks_callback"), $text);
     }
     
     // Handle general block elements over multiple lines
     public function _doGeneralBlocks_callback($matches) {
         $name = $attributes = $attr = "";
         $text = preg_replace("/^[ ]*![ ]?/m", "", $matches[1]);
         if (preg_match("/^[ ]*".$this->id_class_attr_catch_re."[ ]*\n([\S\s]*)$/m", $text, $parts)) {
             $name = $this->getBlockName("", $parts[1]);
             $text = $parts[2];
             $attributes = $parts[1];
             $attr = $this->doExtraAttributes("div", $parts[1]);
         }
         if (!is_string_empty($text)) {
             $output = $this->page->parseContentElement($name, $text, $attributes, "general");
             if (is_null($output)) {
                 $output = "<div$attr>\n".$this->runBlockGamut($text)."\n</div>";
             }
         } else {
             $output = "<div$attr></div>";
         }
         return "\n".$this->hashBlock($output)."\n\n";
     }
     
     // Handle footnotes links, normalise ids and links
     public function doFootnotesLinks($text) {
         if (!is_null($this->footnotes_assembled)) {
             $callbackId = function ($matches) {
                 $id = str_replace(":", "-", $matches[2]);
                 return "<$matches[1] id=\"$id\" $matches[3]>";
             };
             $text = preg_replace_callback("/<(li|sup) id=\"(fn:\d+)\"(.*?)>/", $callbackId, $text);
             $text = preg_replace_callback("/<(li|sup) id=\"(fnref\d*:\d+)\"(.*?)>/", $callbackId, $text);
             $callbackHref = function ($matches) {
                 $href = $this->page->base.$this->page->location.str_replace(":", "-", $matches[2]);
                 return "<$matches[1] href=\"$href\" $matches[3]>";
             };
             $text = preg_replace_callback("/<(a) href=\"(#fn:\d+)\"(.*?)>/", $callbackHref, $text);
             $text = preg_replace_callback("/<(a) href=\"(#fnref\d*:\d+)\"(.*?)>/", $callbackHref, $text);
         }
 		return $text;
     }
                                       
     // Return suitable name for block element
     public function getBlockName($language, $attributes) {
         if (!is_string_empty($language)) {
             $name = ltrim($language, ".");
         } else {
             $name = "";
             foreach (explode(" ", $attributes) as $token) {
                 if (substru($token, 0, 1)==".") { $name = substru($token, 1); break; }
             }
         }
         return $name;
     }
 
     // Return unique id attribute
     public function getIdAttribute($text) {
         $attr = "";
         $text = $this->yellow->lookup->normaliseName($text, true, false, true);
         $text = trim(preg_replace("/-+/", "-", $text), "-");
         if (!isset($this->idAttributes[$text])) {
             $this->idAttributes[$text] = $text;
             $attr = " id=\"$text\"";
         } else {
             $attr = " id=\"error-duplicate-heading\"";
         }
         return $attr;
     }
 }