code:
<?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 Michelf;

//

// Markdown Parser Class

//

class Markdown
{

    // Version ###

    const  MARKDOWNLIB_VERSION  =  "1.3";

    // 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 $parser->transform($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 transform($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
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.:

        //

        //

        // tags for inner block must be indented.

        //

        //

        //

        // 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
. 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 (<?php  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("
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("
empty_element_suffix\n");

    }

    protected function doAnchors($text)
    {

        //

        // Turn Markdown link shortcuts into XHTML  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);

            $result = "titles[$link_id]) ) {

                $title = $this->titles[$link_id];

                $title = $this->encodeAttribute($title);

                $result .=  " title=\"$title\"";

            }

            $link_text = $this->runSpanGamut($link_text);

            $result .= ">$link_text";

            $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);

        $result = "encodeAttribute($title);

            $result .=  " title=\"$title\"";

        }

        $link_text = $this->runSpanGamut($link_text);

        $result .= ">$link_text";

        return $this->hashPart($result);

    }

    protected function doImages($text)
    {

        //

        // Turn Markdown image shortcuts into  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]);

            $result = "titles[$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);

        $result = "encodeAttribute($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 "
" . $item . "
\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 = "
$codeblock\n
";

        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");

    }

    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);

                    $span = "$span";

                    $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);

                    $span = "$span";

                    $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);

                        $span = "$span";

                        $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
 content,

        // so we need to fix that:

        $bq = preg_replace_callback(
            '{(\s*
.+?
)}sx',
            array(&$this, '_doBlockQuotes_callback2'), $bq
        );

        return "\n". $this->hashBlock("
\n$bq\n
")."\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
 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
 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('/^([ ]*)/', "
", $value);

                $value .= "
";

                $grafs[$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 =
 tag

                //
]*

                //                      \b

                //                      markdown\s*=\s*  ([\'"])    #    $2 = attr quote char

                //                      1

                //                      \2

                //                      [^>]*

                //                      >

                //                    )

                //                    (                            # $3 = contents

                //                    .*

                //                    )

                //                    (
)                    # $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('"', '"', $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('&', '&', $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+);)/',
                '&', $text
            );;

        }

        // Encode remaining <'s

        $text = str_replace('<', '<', $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]);

        $link = "$url";

        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.:

        //

        //
foo@exampl

        // e.com

        //

        // 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:`

        $addr = "$text";

        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]];

    }

}

//

// Temporary Markdown Extra Parser Implementation Class

//

// NOTE: DON'T USE THIS CLASS

// Currently the implementation of of Extra resides here in this temporary class.

// This makes it easier to propagate the changes between the three different

// packaging styles of PHP Markdown. When this issue is resolved, this

// MarkdownExtra_TmpImpl class here will disappear and \Michelf\MarkdownExtra

// will contain the code. So please use \Michelf\MarkdownExtra and ignore this

// one.

//

class _MarkdownExtra_TmpImpl extends \Michelf\Markdown
{

    // Configuration Variables ###

    // Prefix for footnote ids.

    public $fn_id_prefix = "";

    // Optional title attribute for footnote links and backlinks.

    public $fn_link_title = "";

    public $fn_backlink_title = "";

    // Optional class attribute for footnote links and backlinks.

    public $fn_link_class = "footnote-ref";

    public $fn_backlink_class = "footnote-backref";

    // 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.

    public $table_align_class_tmpl = '';

    // Optional class prefix for fenced code block.

    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.

    public $code_attr_on_pre = false;

    // Predefined abbreviations.

    public $predef_abbr = array();

    // Parser Implementation ###

    public function __construct()
    {

        //

        // Constructor function. Initialize the parser object.

        //

        // 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,

        );

        parent::__construct();

    }

    // Extra variables used during extra transformations.

    protected $footnotes = array();

    protected $footnotes_ordered = array();

    protected $footnotes_ref_count = array();

    protected $footnotes_numbers = array();

    protected $abbr_desciptions = array();

    protected $abbr_word_re = '';

    // Give the current footnote number.

    protected $footnote_counter = 1;

    protected function setup()
    {

        //

        // Setting up Extra-specific variables.

        //

        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;

        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);

        }

    }

    protected function teardown()
    {

        //

        // Clearing Extra-specific variables.

        //

        $this->footnotes = array();

        $this->footnotes_ordered = array();

        $this->footnotes_ref_count = array();

        $this->footnotes_numbers = array();

        $this->abbr_desciptions = array();

        $this->abbr_word_re = '';

        parent::teardown();

    }

    // Extra Attribute Parser ###

    // Expression to use to catch attributes (includes the braces)

    protected $id_class_attr_catch_re = '\{((?:[ ]*[#.][-_:a-zA-Z0-9]+){1,})[ ]*\}';

    // Expression to use when parsing in a context when no capture is desired

    protected $id_class_attr_nocatch_re = '\{(?:[ ]*[#.][-_:a-zA-Z0-9]+){1,}[ ]*\}';

    protected function doExtraAttributes($tag_name, $attr)
    {

        //

        // 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.

        //

        if (empty($attr)) { return "";
        }

        // Split on components

        preg_match_all('/[#.][-_:a-zA-Z0-9]+/', $attr, $matches);

        $elements = $matches[0];

        // handle classes and ids (only first id taken into account)

        $classes = 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);
                }

            }

        }

        // compose attributes as string

        $attr_str = "";

        if (!empty($id)) {

            $attr_str .= ' id="'.$id.'"';

        }

        if (!empty($classes)) {

            $attr_str .= ' class="'.implode(" ", $classes).'"';

        }

        return $attr_str;

    }

    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

					(?:[ ]* '.$this->id_class_attr_catch_re.' )?  # $5 = extra id & class attr

							(?:\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];

        $this->ref_attr[$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:

    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';

    // Tags treated as block tags only if the opening tag is alone on its line:

    protected $context_block_tags_re = 'script|noscript|ins|del|iframe|object|source|track|param|math|svg|canvas|audio|video';

    // Tags where markdown="1" default to span mode:

    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:

    protected $clean_tags_re = 'script|math|svg';

    // Tags that do not need to be closed.

    protected $auto_close_tags_re = 'hr|img|param|source|track';

    protected function hashHTMLBlocks($text)
    {

        //

        // 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
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!

        //

        if ($this->no_markup) {  return $text;
        }

        //

        // Call the HTML-in-Markdown hasher.

        //

        list($text, ) = $this->_hashHTMLBlocks_inMarkdown($text);

        return $text;

    }

    protected function _hashHTMLBlocks_inMarkdown($text, $indent = 0,
        $enclosing_tag_re = '', $span = false
    ) {

        //

        // 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:

        //

        //

        //

        // Hello World.  <-- Is this a Markdown code block or text?

        //
  <-- Is this a Markdown code block or a real tag?

        //

        //

        // 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 )

        //

        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

				|

					# Code span marker

					`+

				'. ( !$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,}

									[ ]*

					(?:

					\.?[-_:a-zA-Z0-9]+ # standalone class name

					|

						'.$this->id_class_attr_nocatch_re.' # extra attributes

					)?

					[ ]*

					\n

				' : '' ). ' # End (if not is span).

				)

			}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("", ':');

                $newline = "$void\n";

                $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.

            $tag_re = preg_quote($tag); // For use in a regular expression.

            //

            // Check for: Code span marker

            //

            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: Fenced code block marker.

            //

            else if (preg_match('{^\n?([ ]{0,'.($indent+3).'})(~+)}', $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: 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);

    }

    protected function _hashHTMLBlocks_inHTML($text, $hash_method, $md_attr)
    {

        //

        // 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 )

        //

        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.

        //

        // 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
)

            // 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.

                    $this->mode = $attr_m[2] . $attr_m[3];

                    $span_mode = $this->mode == 'span' || $this->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 {                $parsed .= "$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);

    }

    protected function hashClean($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.

        //

        return $this->hashPart($text, 'C');

    }

    protected function doAnchors($text)
    {

        //

        // Turn Markdown link shortcuts into XHTML  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

			  \)

			  (?:[ ]? '.$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;

    }

    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);

            $result = "titles[$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";

            $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];

        $attr  = $this->doExtraAttributes("a", $dummy = & $matches[8]);

        $url = $this->encodeAttribute($url);

        $result = "encodeAttribute($title);

            $result .=  " title=\"$title\"";

        }

        $result .= $attr;

        $link_text = $this->runSpanGamut($link_text);

        $result .= ">$link_text";

        return $this->hashPart($result);

    }

    protected function doImages($text)
    {

        //

        // Turn Markdown image shortcuts into  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

			  \)

			  (?:[ ]? '.$this->id_class_attr_catch_re.' )?	 # $8 = id/class attributes

			)

			}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]);

            $result = "titles[$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;

    }

    protected function _doImages_inline_callback($matches)
    {

        $whole_match    = $matches[1];

        $alt_text        = $matches[2];

        $url            = $matches[3] == '' ? $matches[4] : $matches[3];

        $title            =& $matches[7];

        $attr  = $this->doExtraAttributes("img", $dummy = & $matches[8]);

        $alt_text = $this->encodeAttribute($alt_text);

        $url = $this->encodeAttribute($url);

        $result = "encodeAttribute($title);

            $result .=  " title=\"$title\""; // $title already quoted

        }

        $result .= $attr;

        $result .= $this->empty_element_suffix;

        return $this->hashPart($result);

    }

    protected function doHeaders($text)
    {

        //

        // Redefined to add id and class attribute support.

        //

        // 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

				[ ]*

				(.+?)		# $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;

    }

    protected function _doHeaders_callback_setext($matches)
    {

        if ($matches[3] == '-' && preg_match('{^- }', $matches[1])) {

            return $matches[0];
        }

        $level = $matches[3]{0} == '=' ? 1 : 2;

        $attr  = $this->doExtraAttributes("h$level", $dummy = & $matches[2]);

        $block = "<h$level$attr>".$this->runSpanGamut($matches[1])."</h$level>";

        return "\n" . $this->hashBlock($block) . "\n\n";

    }

    protected function _doHeaders_callback_atx($matches)
    {

        $level = strlen($matches[1]);

        $attr  = $this->doExtraAttributes("h$level", $dummy = & $matches[3]);

        $block = "<h$level$attr>".$this->runSpanGamut($matches[2])."</h$level>";

        return "\n" . $this->hashBlock($block) . "\n\n";

    }

    protected function doTables($text)
    {

        //

        // Form HTML tables.

        //

        $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;

    }

    protected function _doTable_leadingPipe_callback($matches)
    {

        $head        = $matches[1];

        $underline    = $matches[2];

        $content    = $matches[3];

        // Remove leading pipe for each row.

        $content    = preg_replace('/^ *[|]/m', '', $content);

        return $this->_doTable_callback(array($matches[0], $head, $underline, $content));

    }

    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\"";

    }

    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 = "
\n";

        $text .= "
\n";

        $text .= "
\n";

        foreach ($headers as $n => $header) {

            $text .= "  ".$this->runSpanGamut(trim($header))."	\n";
        }

        $text .= "
\n";

        $text .= "
\n";

        // Split content by row.

        $rows = explode("\n", trim($content, "\n"));

        $text .= "
\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 .= "
\n";

            foreach ($row_cells as $n => $cell) {

                $text .= "  ".$this->runSpanGamut(trim($cell))."	\n";
            }

            $text .= "
\n";

        }

        $text .= "
\n";

        $text .= "
";

        return $this->hashBlock($text) . "\n";

    }

    protected function doDefLists($text)
    {

        //

        // Form HTML definition lists.

        //

        $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;

    }

    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 = "
\n" . $result . "\n
";

        return $this->hashBlock($result) . "\n\n";

    }

    protected function processDefListItems($list_str)
    {

        //

        // Process the contents of a single definition list, splitting it

        // into individual term and definition list items.

        //

        $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.'} \:[ ]	|

 | \z

				)

			)

			}xm',
            array(&$this, '_processDefListItems_callback_dd'), $list_str
        );

        return $list_str;

    }

    protected function _processDefListItems_callback_dt($matches)
    {

        $terms = explode("\n", trim($matches[1]));

        $text = '';

        foreach ($terms as $term) {

            $term = $this->runSpanGamut(trim($term));

            $text .= "\n
" . $term . "
";

        }

        return $text . "\n";

    }

    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
" . $def . "
\n";

    }

    protected function doFencedCodeBlocks($text)
    {

        //

        // Adding the fenced code block syntax to regular Markdown:

        //

        // ~~~

        // Code block

        // ~~~

        //

        $less_than_tab = $this->tab_width;

        $text = preg_replace_callback(
            '{

				(?:\n|\A)

				# 1: Opening marker

				(

					~{3,} # Marker: three tilde or more.

				)

				[ ]*

				(?:

					\.?([-_: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;

    }

    protected function _doFencedCodeBlocks_callback($matches)
    {

        $classname =& $matches[2];

        $attrs     =& $matches[3];

        $codeblock = $matches[4];

        $codeblock = htmlspecialchars($codeblock, ENT_NOQUOTES);

        $codeblock = preg_replace_callback(
            '/^\n+/',
            array(&$this, '_doFencedCodeBlocks_newlines'), $codeblock
        );

        if ($classname != "") {

            if ($classname{0} == '.') {

                $classname = substr($classname, 1);
            }

            $attr_str = ' class="'.$this->code_class_prefix.$classname.'"';

        } else {

            $attr_str = $this->doExtraAttributes($this->code_attr_on_pre ? "pre" : "code", $attrs);

        }

        $pre_attr_str  = $this->code_attr_on_pre ? $attr_str : '';

        $code_attr_str = $this->code_attr_on_pre ? '' : $attr_str;

        $codeblock  = "
$codeblock
";

        return "\n\n".$this->hashBlock($codeblock)."\n\n";

    }

    protected function _doFencedCodeBlocks_newlines($matches)
    {

        return str_repeat(
            "
empty_element_suffix",
            strlen($matches[0])
        );

    }

    //

    // Redefining emphasis markers so that emphasis by underscore does not

    // work in the middle of a word.

    //

    protected $em_relist = array(

    ''  => '(?:(?<!\*)\*(?!\*)|(?<![a-zA-Z0-9_])_(?!_))(?=\S|$)(?![\.,:;]\s)',

    '*' => '(?<=\S|^)(?<!\*)\*(?!\*)',

    '_' => '(?<=\S|^)(?<!_)_(?![a-zA-Z0-9_])',

    );

    protected $strong_relist = array(

    ''   => '(?:(?<!\*)\*\*(?!\*)|(?<![a-zA-Z0-9_])__(?!_))(?=\S|$)(?![\.,:;]\s)',

    '**' => '(?<=\S|^)(?<!\*)\*\*(?!\*)',

    '__' => '(?<=\S|^)(?<!_)__(?![a-zA-Z0-9_])',

    );

    protected $em_strong_relist = array(

    ''    => '(?:(?<!\*)\*\*\*(?!\*)|(?<![a-zA-Z0-9_])___(?!_))(?=\S|$)(?![\.,:;]\s)',

    '***' => '(?<=\S|^)(?<!\*)\*\*\*(?!\*)',

    '___' => '(?<=\S|^)(?<!_)___(?![a-zA-Z0-9_])',

    );

    protected function formParagraphs($text)
    {

        //

        // Params:

        // $text - string to process with html
 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
 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.

            $is_p = !preg_match('/^B\x1A[0-9]+B|^C\x1A[0-9]+C$/', $value);

            if ($is_p) {

                $value = "
$value
";

            }

            $grafs[$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

    protected function stripFootnotes($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.'}\[\^(.+?)\][ ]?:	# note_id = $1

			  [ ]*

			  \n?					# maybe *one* newline

			(						# text = $2 (no blank lines allowed)

				(?:

					.+				# actual text

				|

					\n				# newlines but

					(?!\[\^.+?\]:\s)# negative lookahead for footnote marker.

					(?!\n+[ ]{0,3}\S)# ensure line is not blank and followed

									# by non-indented content

				)*

			)

			}xm',
            array(&$this, '_stripFootnotes_callback'),
            $text
        );

        return $text;

    }

    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

    }

    protected function doFootnotes($text)
    {

        //

        // Replace footnote references in $text [^id] with a special text-token

        // which will be replaced by the actual footnote marker in appendFootnotes.

        //

        if (!$this->in_anchor) {

            $text = preg_replace('{\[\^(.+?)\]}', "F\x1Afn:\\1\x1A:", $text);

        }

        return $text;

    }

    protected function appendFootnotes($text)
    {

        //

        // Append footnote list to text.

        //

        $text = preg_replace_callback(
            '{F\x1Afn:(.*?)\x1A:}',
            array(&$this, '_appendFootnotes_callback'), $text
        );

        if (!empty($this->footnotes_ordered)) {

            $text .= "\n\n";

            $text .= "
\n";

            $text .= "
empty_element_suffix ."\n";

            $text .= "
\n\n";

            $attr = " rev=\"footnote\"";

            if ($this->fn_backlink_class != "") {

                $class = $this->fn_backlink_class;

                $class = $this->encodeAttribute($class);

                $attr .= " class=\"$class\"";

            }

            if ($this->fn_backlink_title != "") {

                $title = $this->fn_backlink_title;

                $title = $this->encodeAttribute($title);

                $attr .= " title=\"$title\"";

            }

            $num = 0;

            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
                );

                $attr = str_replace("%%", ++$num, $attr);

                $note_id = $this->encodeAttribute($note_id);

                // Prepare backlink, multiple backlinks if multiple references

                $backlink = "↩";

                for ($ref_num = 2; $ref_num <= $ref_count; ++$ref_num) {

                    $backlink .= " ↩";

                }

                // Add backlink to last paragraph; create new paragraph if needed.

                if (preg_match('{
$}', $footnote)) {

                    $footnote = substr($footnote, 0, -4) . " $backlink
";

                } else {

                    $footnote .= "\n\n
$backlink
";

                }

                $text .= "
\n";

                $text .= $footnote . "\n";

                $text .= "
\n\n";

            }

            $text .= "
\n";

            $text .= "
";

        }

        return $text;

    }

    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 = str_replace("%%", $num, $attr);

            $node_id = $this->encodeAttribute($node_id);

            return

            "".

            "$num".

            "";

        }

        return "[^".$matches[1]."]";

    }

    // Abbreviations ###

    protected function stripAbbreviations($text)
    {

        //

        // Strips abbreviations from text, stores 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.'}\*\[(.+?)\][ ]?:	# abbr_id = $1

			(.*)					# text = $2 (no blank lines allowed)

			}xm',
            array(&$this, '_stripAbbreviations_callback'),
            $text
        );

        return $text;

    }

    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

    }

    protected function doAbbreviations($text)
    {

        //

        // Find defined abbreviations in text and wrap them in  elements.

        //

        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;

    }

    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");

            } else {

                $desc = $this->encodeAttribute($desc);

                return $this->hashPart("$abbr");

            }

        } else {

            return $matches[0];

        }

    }

}

?>