diff --git a/Think/Parser/Driver/Markdown.php b/Think/Parser/Driver/Markdown.php
new file mode 100644
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--- /dev/null
+++ b/Think/Parser/Driver/Markdown.php
@@ -0,0 +1,1523 @@
+<?php
+#
+# Markdown  -  A text-to-HTML conversion tool for web writers
+#
+# PHP Markdown  
+# Copyright (c) 2004-2013 Michel Fortin  
+# <http://michelf.com/projects/php-markdown/>
+#
+# Original Markdown  
+# Copyright (c) 2004-2006 John Gruber  
+# <http://daringfireball.net/projects/markdown/>
+#
+
+namespace Think\Parser\Driver;
+
+#
+# The following two constants are deprecated: avoid using them, they'll
+# disappear when the Lib branch becomes the only one to be updated.
+#
+# You can get the parser's version using the constant inside of the parser
+# class: \Michelf\Markdown::MARKDOWNLIB_VERSION.
+#
+
+const  MARKDOWN_VERSION  =  "1.0.1p";  # Sun 13 Jan 2013
+const  MARKDOWNEXTRA_VERSION  =  "1.2.6";  # Sun 13 Jan 2013
+
+#
+# Markdown Parser Class
+#
+
+class Markdown {
+
+	### Version ###
+
+	const MARKDOWNLIB_VERSION  =  "1.3-beta4";
+
+	### Simple Function Interface ###
+
+	public static function defaultTransform($text) {
+	#
+	# Initialize the parser and return the result of its transform method.
+	# This will work fine for derived classes too.
+	#
+		# 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 $parser->parse($text);
+	}
+
+	### Configuration Variables ###
+
+	# Change to ">" for HTML output.
+	public $empty_element_suffix = " />";
+	public $tab_width = 4;
+	
+	# Change to `true` to disallow markup or entities.
+	public $no_markup = false;
+	public $no_entities = false;
+	
+	# Predefined urls and titles for reference links and images.
+	public $predef_urls = array();
+	public $predef_titles = array();
+
+
+	### Parser Implementation ###
+
+	# Regex to match balanced [brackets].
+	# Needed to insert a maximum bracked depth while converting to PHP.
+	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:
+	protected $escape_chars = '\`*_{}[]()>#+-.!';
+	protected $escape_chars_re;
+
+
+	public function __construct() {
+	#
+	# Constructor function. Initialize appropriate member variables.
+	#
+		$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.
+	protected $urls = array();
+	protected $titles = array();
+	protected $html_hashes = array();
+	
+	# Status flag to avoid invalid nesting.
+	protected $in_anchor = false;
+	
+	
+	protected function setup() {
+	#
+	# Called before the transformation process starts to setup parser 
+	# states.
+	#
+		# Clear global hashes.
+		$this->urls = $this->predef_urls;
+		$this->titles = $this->predef_titles;
+		$this->html_hashes = array();
+		
+		$this->in_anchor = false;
+	}
+	
+	protected function teardown() {
+	#
+	# Called after the transformation process to clear any variable 
+	# which may be taking up memory unnecessarly.
+	#
+		$this->urls = array();
+		$this->titles = array();
+		$this->html_hashes = array();
+	}
+
+
+	public function parse($text) {
+	#
+	# Main function. Performs some preprocessing on the input text
+	# and pass it through the document gamut.
+	#
+		$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";
+	}
+	
+	protected $document_gamut = array(
+		# Strip link definitions, store in hashes.
+		"stripLinkDefinitions" => 20,
+		
+		"runBasicBlockGamut"   => 30,
+		);
+
+
+	protected function stripLinkDefinitions($text) {
+	#
+	# Strips link definitions from text, stores the URLs and titles in
+	# hash references.
+	#
+		$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 $text;
+	}
+	protected function _stripLinkDefinitions_callback($matches) {
+		$link_id = strtolower($matches[1]);
+		$url = $matches[2] == '' ? $matches[3] : $matches[2];
+		$this->urls[$link_id] = $url;
+		$this->titles[$link_id] =& $matches[4];
+		return ''; # String that will replace the block
+	}
+
+
+	protected function hashHTMLBlocks($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|form|fieldset|iframe|math|svg|'.
+						   'article|section|nav|aside|hgroup|header|footer|'.
+						   'figure';
+
+		# 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\n)		# Starting after a blank line
+				|				# or
+				\A\n?			# the 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 $text;
+	}
+	protected function _hashHTMLBlocks_callback($matches) {
+		$text = $matches[1];
+		$key  = $this->hashBlock($text);
+		return "\n\n$key\n\n";
+	}
+	
+	
+	protected function hashPart($text, $boundary = 'X') {
+	#
+	# 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.
+	#
+		# 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 $key; # String that will replace the tag.
+	}
+
+
+	protected function hashBlock($text) {
+	#
+	# Shortcut function for hashPart with block-level boundaries.
+	#
+		return $this->hashPart($text, 'B');
+	}
+
+
+	protected $block_gamut = array(
+	#
+	# These are all the transformations that form block-level
+	# tags like paragraphs, headers, and list items.
+	#
+		"doHeaders"         => 10,
+		"doHorizontalRules" => 20,
+		
+		"doLists"           => 40,
+		"doCodeBlocks"      => 50,
+		"doBlockQuotes"     => 60,
+		);
+
+	protected function runBlockGamut($text) {
+	#
+	# 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.
+		$text = $this->hashHTMLBlocks($text);
+		
+		return $this->runBasicBlockGamut($text);
+	}
+	
+	protected function runBasicBlockGamut($text) {
+	#
+	# Run block gamut tranformations, without hashing HTML blocks. This is 
+	# useful when HTML blocks are known to be already hashed, like in the first
+	# whole-document pass.
+	#
+		foreach ($this->block_gamut as $method => $priority) {
+			$text = $this->$method($text);
+		}
+		
+		# Finally form paragraph and restore hashed blocks.
+		$text = $this->formParagraphs($text);
+
+		return $text;
+	}
+	
+	
+	protected function doHorizontalRules($text) {
+		# Do Horizontal Rules:
+		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);
+	}
+
+
+	protected $span_gamut = array(
+	#
+	# These are all the transformations that occur *within* block-level
+	# tags like paragraphs, headers, and list items.
+	#
+		# Process character escapes, code spans, and inline HTML
+		# in one shot.
+		"parseSpan"           => -30,
+
+		# Process anchor and image tags. Images must come first,
+		# because ![foo][f] looks like an anchor.
+		"doImages"            =>  10,
+		"doAnchors"           =>  20,
+		
+		# Make links out of things like `<http://example.com/>`
+		# Must come after doAnchors, because you can use < and >
+		# delimiters in inline links like [this](<url>).
+		"doAutoLinks"         =>  30,
+		"encodeAmpsAndAngles" =>  40,
+
+		"doItalicsAndBold"    =>  50,
+		"doHardBreaks"        =>  60,
+		);
+
+	protected function runSpanGamut($text) {
+	#
+	# Run span gamut tranformations.
+	#
+		foreach ($this->span_gamut as $method => $priority) {
+			$text = $this->$method($text);
+		}
+
+		return $text;
+	}
+	
+	
+	protected function doHardBreaks($text) {
+		# Do hard breaks:
+		return preg_replace_callback('/ {2,}\n/', 
+			array(&$this, '_doHardBreaks_callback'), $text);
+	}
+	protected function _doHardBreaks_callback($matches) {
+		return $this->hashPart("<br$this->empty_element_suffix\n");
+	}
+
+
+	protected function doAnchors($text) {
+	#
+	# Turn Markdown link shortcuts into XHTML <a> tags.
+	#
+		if ($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 $text;
+	}
+	protected function _doAnchors_reference_callback($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 = $this->encodeAttribute($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 $result;
+	}
+	protected function _doAnchors_inline_callback($matches) {
+		$whole_match	=  $matches[1];
+		$link_text		=  $this->runSpanGamut($matches[2]);
+		$url			=  $matches[3] == '' ? $matches[4] : $matches[3];
+		$title			=& $matches[7];
+
+		$url = $this->encodeAttribute($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);
+	}
+
+
+	protected function doImages($text) {
+	#
+	# Turn Markdown image shortcuts into <img> tags.
+	#
+		#
+		# 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 $text;
+	}
+	protected function _doImages_reference_callback($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 = $this->encodeAttribute($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 $result;
+	}
+	protected function _doImages_inline_callback($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 = $this->encodeAttribute($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);
+	}
+
+
+	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 $text;
+	}
+	protected function _doHeaders_callback_setext($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;
+		$block = "<h$level>".$this->runSpanGamut($matches[1])."</h$level>";
+		return "\n" . $this->hashBlock($block) . "\n\n";
+	}
+	protected function _doHeaders_callback_atx($matches) {
+		$level = strlen($matches[1]);
+		$block = "<h$level>".$this->runSpanGamut($matches[2])."</h$level>";
+		return "\n" . $this->hashBlock($block) . "\n\n";
+	}
+
+
+	protected function doLists($text) {
+	#
+	# Form HTML ordered (numbered) and unordered (bulleted) lists.
+	#
+		$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+[\.]';
+		$marker_any_re = "(?:$marker_ul_re|$marker_ol_re)";
+
+		$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 $text;
+	}
+	protected function _doLists_callback($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)";
+		
+		$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);
+		
+		$result = $this->hashBlock("<$list_type>\n" . $result . "</$list_type>");
+		return "\n". $result ."\n\n";
+	}
+
+	protected $list_level = 0;
+
+	protected function processListItems($list_str, $marker_any_re) {
+	#
+	#	Process the contents of a single ordered or unordered list, splitting it
+	#	into individual list items.
+	#
+		# 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 $list_str;
+	}
+	protected function _processListItems_callback($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));
+			$item = preg_replace('/\n+$/', '', $item);
+			$item = $this->runSpanGamut($item);
+		}
+
+		return "<li>" . $item . "</li>\n";
+	}
+
+
+	protected function doCodeBlocks($text) {
+	#
+	#	Process Markdown `<pre><code>` blocks.
+	#
+		$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 $text;
+	}
+	protected function _doCodeBlocks_callback($matches) {
+		$codeblock = $matches[1];
+
+		$codeblock = $this->outdent($codeblock);
+		$codeblock = htmlspecialchars($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";
+	}
+
+
+	protected function makeCodeSpan($code) {
+	#
+	# Create a code span markup for $code. Called from handleSpanToken.
+	#
+		$code = htmlspecialchars(trim($code), ENT_NOQUOTES);
+		return $this->hashPart("<code>$code</code>");
+	}
+
+
+	protected $em_relist = array(
+		''  => '(?:(?<!\*)\*(?!\*)|(?<!_)_(?!_))(?=\S|$)(?![\.,:;]\s)',
+		'*' => '(?<=\S|^)(?<!\*)\*(?!\*)',
+		'_' => '(?<=\S|^)(?<!_)_(?!_)',
+		);
+	protected $strong_relist = array(
+		''   => '(?:(?<!\*)\*\*(?!\*)|(?<!_)__(?!_))(?=\S|$)(?![\.,:;]\s)',
+		'**' => '(?<=\S|^)(?<!\*)\*\*(?!\*)',
+		'__' => '(?<=\S|^)(?<!_)__(?!_)',
+		);
+	protected $em_strong_relist = array(
+		''    => '(?:(?<!\*)\*\*\*(?!\*)|(?<!_)___(?!_))(?=\S|$)(?![\.,:;]\s)',
+		'***' => '(?<=\S|^)(?<!\*)\*\*\*(?!\*)',
+		'___' => '(?<=\S|^)(?<!_)___(?!_)',
+		);
+	protected $em_strong_prepared_relist;
+	
+	protected function prepareItalicsAndBold() {
+	#
+	# Prepare regular expressions for searching emphasis tokens in any
+	# context.
+	#
+		foreach ($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"] = $token_re;
+			}
+		}
+	}
+	
+	protected function doItalicsAndBold($text) {
+		$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);
+					}
+					# 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;
+				}
+			}
+		}
+		return $text_stack[0];
+	}
+
+
+	protected function doBlockQuotes($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 $text;
+	}
+	protected function _doBlockQuotes_callback($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";
+	}
+	protected function _doBlockQuotes_callback2($matches) {
+		$pre = $matches[1];
+		$pre = preg_replace('/^  /m', '', $pre);
+		return $pre;
+	}
+
+
+	protected function formParagraphs($text) {
+	#
+	#	Params:
+	#		$text - string to process with html <p> tags
+	#
+		# 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);
+				$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", $grafs);
+	}
+
+
+	protected function encodeAttribute($text) {
+	#
+	# Encode text for a double-quoted HTML attribute. This function
+	# is *not* suitable for attributes enclosed in single quotes.
+	#
+		$text = $this->encodeAmpsAndAngles($text);
+		$text = str_replace('"', '&quot;', $text);
+		return $text;
+	}
+	
+	
+	protected function encodeAmpsAndAngles($text) {
+	#
+	# 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.
+	#
+		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 $text;
+	}
+
+
+	protected function doAutoLinks($text) {
+		$text = preg_replace_callback('{<((https?|ftp|dict):[^\'">\s]+)>}i', 
+			array(&$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 $text;
+	}
+	protected function _doAutoLinks_url_callback($matches) {
+		$url = $this->encodeAttribute($matches[1]);
+		$link = "<a href=\"$url\">$url</a>";
+		return $this->hashPart($link);
+	}
+	protected function _doAutoLinks_email_callback($matches) {
+		$address = $matches[1];
+		$link = $this->encodeEmailAddress($address);
+		return $this->hashPart($link);
+	}
+
+
+	protected function encodeEmailAddress($addr) {
+	#
+	#	Input: an email address, e.g. "foo@example.com"
+	#
+	#	Output: the email address as a mailto link, with each character
+	#		of the address encoded as either a decimal or hex entity, in
+	#		the hopes of foiling most address harvesting spam bots. E.g.:
+	#
+	#	  <p><a href="&#109;&#x61;&#105;&#x6c;&#116;&#x6f;&#58;&#x66;o&#111;
+	#        &#x40;&#101;&#x78;&#97;&#x6d;&#112;&#x6c;&#101;&#46;&#x63;&#111;
+	#        &#x6d;">&#x66;o&#111;&#x40;&#101;&#x78;&#97;&#x6d;&#112;&#x6c;
+	#        &#101;&#46;&#x63;&#111;&#x6d;</a></p>
+	#
+	#	Based by a filter by Matthew Wickline, posted to BBEdit-Talk.
+	#   With some optimizations by Milian Wolff.
+	#
+		$addr = "mailto:" . $addr;
+		$chars = preg_split('/(?<!^)(?!$)/', $addr);
+		$seed = (int)abs(crc32($addr) / strlen($addr)); # Deterministic seed.
+		
+		foreach ($chars as $key => $char) {
+			$ord = ord($char);
+			# Ignore non-ascii chars.
+			if ($ord < 128) {
+				$r = ($seed * (1 + $key)) % 100; # Pseudo-random function.
+				# roughly 10% raw, 45% hex, 45% dec
+				# '@' *must* be encoded. I insist.
+				if ($r > 90 && $char != '@') /* do nothing */;
+				else if ($r < 45) $chars[$key] = '&#x'.dechex($ord).';';
+				else              $chars[$key] = '&#'.$ord.';';
+			}
+		}
+		
+		$addr = implode('', $chars);
+		$text = implode('', array_slice($chars, 7)); # text without `mailto:`
+		$addr = "<a href=\"$addr\">$text</a>";
+
+		return $addr;
+	}
+
+
+	protected function parseSpan($str) {
+	#
+	# Take the string $str and parse it into tokens, hashing embeded HTML,
+	# escaped characters and handling code spans.
+	#
+		$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 $output;
+	}
+	
+	
+	protected function handleSpanToken($token, &$str) {
+	#
+	# Handle $token provided by parseSpan by determining its nature and 
+	# returning the corresponding value that should replace it.
+	#
+		switch ($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);
+		}
+	}
+
+
+	protected function outdent($text) {
+	#
+	# Remove one level of line-leading tabs or spaces
+	#
+		return preg_replace('/^(\t|[ ]{1,'.$this->tab_width.'})/m', '', $text);
+	}
+
+
+	# String length function for detab. `_initDetab` will create a function to 
+	# hanlde UTF-8 if the default function does not exist.
+	protected $utf8_strlen = 'mb_strlen';
+	
+	protected function detab($text) {
+	#
+	# Replace tabs with the appropriate amount of space.
+	#
+		# 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.
+		
+		$text = preg_replace_callback('/^.*\t.*$/m',
+			array(&$this, '_detab_callback'), $text);
+
+		return $text;
+	}
+	protected function _detab_callback($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 $line;
+	}
+	protected function _initDetab() {
+	#
+	# Check for the availability of the function in the `utf8_strlen` property
+	# (initially `mb_strlen`). If the function is not available, create a 
+	# function that will loosely count the number of UTF-8 characters with a
+	# regular expression.
+	#
+		if (function_exists($this->utf8_strlen)) return;
+		$this->utf8_strlen = create_function('$text', 'return preg_match_all(
+			"/[\\\\x00-\\\\xBF]|[\\\\xC0-\\\\xFF][\\\\x80-\\\\xBF]*/", 
+			$text, $m);');
+	}
+
+
+	protected function unhash($text) {
+	#
+	# Swap back in all the tags hashed by _HashHTMLBlocks.
+	#
+		return preg_replace_callback('/(.)\x1A[0-9]+\1/', 
+			array(&$this, '_unhash_callback'), $text);
+	}
+	protected function _unhash_callback($matches) {
+		return $this->html_hashes[$matches[0]];
+	}
+
+}
diff --git a/Think/Parser/Driver/Ubb.php b/Think/Parser/Driver/Ubb.php
new file mode 100644
index 00000000..667a4456
--- /dev/null
+++ b/Think/Parser/Driver/Ubb.php
@@ -0,0 +1,291 @@
+<?php
+// +----------------------------------------------------------------------
+// | TOPThink [ WE CAN DO IT JUST THINK ]
+// +----------------------------------------------------------------------
+// | Copyright (c) 2010 http://topthink.com All rights reserved.
+// +----------------------------------------------------------------------
+// | Licensed ( http://www.apache.org/licenses/LICENSE-2.0 )
+// +----------------------------------------------------------------------
+// | Author: 麦当苗儿 <zuojiazi.cn@gmail.com> <http://www.zjzit.cn>
+// +----------------------------------------------------------------------
+// | Ubb.php 2013-04-03
+// +----------------------------------------------------------------------
+
+namespace Think\Parser\Driver;
+
+class Ubb{
+	/**
+	 * UBB标签匹配规则
+	 * @var array
+	 */
+	private $ubb = [
+		['table'  , '\[table(?:=([\d%]*))?\]', '\[\/table\]', 'width'],
+		['tr'     , '\[tr\]', '\[\/tr\]', 'tag'],
+		['th'     , '\[th(?:=([\d%]*)(?:,([\d%]*))?)?\]', '\[\/th\]', 'widthAndHeight'],
+		['td'     , '\[td(?:=([\d%]*)(?:,([\d%]*))?)?\]', '\[\/td\]', 'widthAndHeight'],
+		['img'    , '\[img(?:=([\d%]*)(?:,([\d%]*))?)?\]', '\[\/img\]', 'imgWidthAndHeight'],
+		['img'    , '\[img=(.*?)(?:,([\d%]*)(?:,([\d%]*))?)?\/\]', 'img'],
+		['a'      , '\[url(?:=(.*?)(?:,([\w\-]*))?)?\]', '\[\/url\]', 'urlClass'],
+		['a'      , '\[a(?:=(.*?)(?:,([\w\-]*))?)?\]', '\[\/a\]', 'urlClass'],
+		['a'      , '\[url=(.*?)(?:,([\w\-]*))?\/\]', 'url'],
+		['a'      , '\[a=(.*?)(?:,([\w\-]*))?\/\]', 'url'],
+		['a'      , '\[email(?:=([\w\-]*))?\]', '\[\/email\]', 'emailClass'],
+		['ul'     , '\[ul(?:=([\w\-]*))?\]', '\[\/ul\]', 'class'],
+		['ol'     , '\[ol(?:=([\w\-]*))?\]', '\[\/ol\]', 'class'],
+		['li'     , '\[li(?:=([\w\-]*))?\]', '\[\/li\]', 'class'],
+		['span'   , '\[span(?:=([\w\-]*))?\]', '\[\/span\]', 'class'],
+		['div'    , '\[div(?:=([\w\-]*))?\]', '\[\/div\]', 'class'],
+		['p'      , '\[p(?:=([\w\-]*))?\]', '\[\/p\]', 'class'],
+		['strong' , '\[b\]', '\[\/b\]', 'tag'],
+		['strong' , '\[strong\]', '\[\/strong\]', 'tag'],
+		['i'      , '\[i\]', '\[\/i\]', 'tag'],
+		['em'     , '\[em\]', '\[\/em\]', 'tag'],
+		['sub'    , '\[sub\]', '\[\/sub\]', 'tag'],
+		['sup'    , '\[sup\]', '\[\/sup\]', 'tag'],
+		['pre'    , '\[code(?:=([a-z#\+\/]*))?\]', '\[\/code\]', 'code'],
+		['code'   , '\[line(?:=([a-z#\+\/]*))?\]', '\[\/line\]', 'code'],
+	];
+
+	/**
+	 * 解析UBB代码为HTML
+	 * @param  string $content 要解析的UBB代码
+	 * @return string          解析后的HTML代码
+	 */
+	public function parse($content = ''){
+		if(empty($content)) return '';
+
+		for($i = 0, $count = count($this->ubb); $i < $count; $i++){
+			if(count($this->ubb[$i]) == 4){ //解析闭合标签
+				$content = $this->closeTag($content, $this->ubb[$i]);
+			} else {
+				$content = $this->onceTag($content, $this->ubb[$i]);
+			}
+		}
+
+		return nl2br($content);
+	}
+
+	/**
+	 * 解析闭合标签，支持嵌套
+	 * @param  string $data 要解析的数据
+	 * @param  array  $rule 解析规则
+	 * @return string       解析后的内容
+	 */
+	private function closeTag($data, $rule = ''){
+		static $tag, $reg, $func, $count = 0;
+		if(is_string($data)){
+			list($tag, $reg[0], $reg[1], $func) = $rule;
+			do{
+				$data  = preg_replace_callback("/({$reg[0]})(.*?)({$reg[1]})/is", 
+					[$this, 'closeTag'], $data);
+			} while ($count && $count--); //递归解析，直到嵌套解析完毕
+			return $data;
+		} elseif(is_array($data)){
+			$num = count($data);
+			if(preg_match("/{$reg[0]}/is", $data[$num-2])){ //存在嵌套，进一步解析
+				$count = 1;
+				$data[$num-2] = preg_replace_callback("/({$reg[0]})(.*?)({$reg[1]})/is", 
+					[$this, 'closeTag'], $data[$num-2] . $data[$num-1]);
+				return $data[1] . $data[$num-2];
+			} else { //不存在嵌套，直接解析内容
+				$parse = '_' . $func;
+				$data[$num-2] = trim($data[$num-2], "\r\n"); //去掉标签内容两端的空格
+				return $this->$parse($tag, $data);
+			}
+		}
+	}
+
+	/**
+	 * 解析单标签
+	 * @param  string $data 要解析的数据
+	 * @param  array  $rule 解析规则
+	 * @return string       解析后的内容
+	 */
+	private function onceTag($data, $rule = ''){
+		list($tag, $reg, $func) = $rule;
+		return preg_replace_callback("/{$reg}/is", [$this, '_' . $func], $data);
+	}
+
+	/**
+	 * 解析img单标签
+	 * @param  array $data 解析数据
+	 * @return string      解析后的标签
+	 */
+	private function _img($data){
+		$data[4] = $data[1];
+		return $this->_imgWidthAndHeight('', $data);
+	}
+
+	/**
+	 * 解析url单标签
+	 * @param  array $data 解析数据
+	 * @return string      解析后的标签
+	 */
+	private function _url($data){
+		$data[3] = $data[2];
+		$data[4] = $data[2] = $data[1];
+		return $this->_urlClass('', $data);
+	}
+
+	/**
+	 * 解析没有属性的标签
+	 * @param  string $name 标签名
+	 * @param  array  $data 解析数据 [2] - 标签内容
+	 * @return string       解析后的标签
+	 */
+	private function _tag($name, $data){
+		return "<{$name}>{$data[2]}</{$name}>";
+	}
+
+	/**
+	 * 解析代码
+	 * @param  string $name 标签名
+	 * @param  array  $data 解析数据 [2] - 语言类型，[3] - 代码内容
+	 * @return string       解析后的标签
+	 */
+	private function _code($name, $data){
+		$fix = ($name == 'pre') ? ['<pre>', '</pre>'] : ['', ''];
+		if(empty($data[2])){
+			$data = "{$fix[0]}<code>{$data[3]}</code>{$fix[1]}";
+		} else {
+			$data = "{$fix[0]}<code data-lang=\"{$data[2]}\">{$data[3]}</code>{$fix[1]}";
+		}
+		return $data;
+	}
+
+	/**
+	 * 解析含有width属性的标签
+	 * @param  string $name 标签名
+	 * @param  array  $data 解析数据 [2] - width, [3] - 标签内容
+	 * @return string       解析后的标签
+	 */
+	private function _width($name, $data){
+		if(empty($data[2])){
+			$data = "<{$name}>{$data[3]}</{$name}>";
+		} else {
+			$data = "<{$name} width=\"{$data[2]}\">{$data[3]}</{$name}>";
+		}
+		return $data;
+	}
+
+	/**
+	 * 解析含有width和height属性的标签
+	 * @param  string $name 标签名
+	 * @param  array  $data 解析数据 [2] - width, [3] - height, [4] - 标签内容
+	 * @return string       解析后的标签
+	 */
+	private function _widthAndHeight($name, $data){
+		if(empty($data[2]) && empty($data[3])){
+			$data = "<{$name}>{$data[4]}</{$name}>";
+		} elseif(!empty($data[2]) && empty($data[3])) {
+			$data = "<{$name} width=\"{$data[2]}\">{$data[4]}</{$name}>";
+		} elseif(empty($data[2]) && !empty($data[3])) {
+			$data = "<{$name} height=\"{$data[3]}\">{$data[4]}</{$name}>";
+		} else {
+			$data = "<{$name} width=\"{$data[2]}\" height=\"{$data[3]}\">{$data[4]}</{$name}>";
+		}
+		return $data;
+	}
+
+	/**
+	 * 解析含有width和height属性的图片标签
+	 * @param  string $name 标签名
+	 * @param  array  $data 解析数据 [2] - width, [3] - height, [4] - 图片URL
+	 * @return string       解析后的标签
+	 */
+	private function _imgWidthAndHeight($name, $data){
+		if(empty($data[2]) && empty($data[3])){
+			$data = "<img src=\"{$data[4]}\" />";
+		} elseif(!empty($data[2]) && empty($data[3])) {
+			$data = "<img width=\"{$data[2]}\" src=\"{$data[4]}\" />";
+		} elseif(empty($data[2]) && !empty($data[3])) {
+			$data = "<img height=\"{$data[3]}\" src=\"{$data[4]}\" />";
+		} else {
+			$data = "<img width=\"{$data[2]}\" height=\"{$data[3]}\" src=\"{$data[4]}\" />";
+		}
+		return $data;
+	}
+
+	/**
+	 * 解析含有class属性的标签
+	 * @param  string $name 标签名
+	 * @param  array  $data 解析数据 [2] - class, [3] - 标签内容
+	 * @return string       解析后的标签
+	 */
+	private function _class($name, $data){
+		if(empty($data[2])){
+			$data = "<{$name}>{$data[3]}</{$name}>";
+		} else {
+			$data = "<{$name} class=\"{$data[2]}\">{$data[3]}</{$name}>";
+		}
+		return $data;
+	}
+
+	/**
+	 * 解析含有class属性的url标签
+	 * @param  string $name 标签名
+	 * @param  array  $data 解析数据 [2] - url, [3] - text
+	 * @return string       解析后的标签
+	 */
+	private function _urlClass($name, $data){
+		empty($data[2]) && $data[2] = $data[4];
+		if(empty($data[3])){
+			$data = "<a href=\"{$data[2]}\">{$data[4]}</a>";
+		} else {
+			$data = "<a href=\"{$data[2]}\" class=\"{$data[3]}\">{$data[4]}</a>";
+		}
+		return $data;
+	}
+
+	/**
+	 * 解析含有class属性的email标签
+	 * @param  string $name 标签名
+	 * @param  array  $data 解析数据 [2] - class, [3] - email地址
+	 * @return string       解析后的标签
+	 */
+	private function _emailClass($name, $data){
+		//不是正确的EMAIL则不解析
+		if(preg_match('/^\w+([-+.]\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*$/', $data[3])) 
+			return $data[0];
+
+		//编码email地址，防治被采集
+		$email = $this->encodeEmailAddress($data[3]);
+		
+		if(empty($data[2])){
+			$data = "<a href=\"{$email[0]}\">{$email[1]}</a>";
+		} else {
+			$data = "<a href=\"{$email[0]}\" class=\"{$data[2]}\">{$email[1]}</a>";
+		}
+		return $data;
+	}
+
+	/**
+	 * 编码EMAIL地址，可以防治部分采集软件
+	 * @param  string $addr EMAIL地址
+	 * @return array        编码后的EMAIL地址 [0] - 带mailto, [1] - 不带mailto
+	 */
+	private function encodeEmailAddress($addr) {
+		$addr = "mailto:" . $addr;
+		$chars = preg_split('/(?<!^)(?!$)/', $addr);
+		$seed = (int)abs(crc32($addr) / strlen($addr)); # Deterministic seed.
+		
+		foreach ($chars as $key => $char) {
+			$ord = ord($char);
+			# Ignore non-ascii chars.
+			if ($ord < 128) {
+				$r = ($seed * (1 + $key)) % 100; # Pseudo-random function.
+				# roughly 10% raw, 45% hex, 45% dec
+				# '@' *must* be encoded. I insist.
+				if ($r > 90 && $char != '@') /* do nothing */;
+				else if ($r < 45) $chars[$key] = '&#x'.dechex($ord).';';
+				else              $chars[$key] = '&#'.$ord.';';
+			}
+		}
+		
+		$addr = implode('', $chars);
+		$text = implode('', array_slice($chars, 7)); # text without `mailto:`
+
+		return [$addr, $text];
+	}
+
+}