/includes/smarty/plugins/modifier.markdown.php

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<?php

#
# PHP Markdown Extra  -  A text-to-HTML conversion tool for web writers
#
# Copyright (c) 2004-2005 Michel Fortin  
# <http://www.michelf.com/projects/php-markdown/>
#
# Based on Markdown  
# Copyright (c) 2004-2005 John Gruber  
# <http://daringfireball.net/projects/markdown/>
#


global	$MarkdownPHPVersion, $MarkdownSyntaxVersion,
		$md_empty_element_suffix, $md_tab_width,
		$md_nested_brackets_depth, $md_nested_brackets, 
		$md_escape_table, $md_backslash_escape_table, 
		$md_list_level;

$MarkdownPHPVersion    = 'Extra 1.0'; # Mon 5 Sep 2005
$MarkdownSyntaxVersion = '1.0.1';  # Sun 12 Dec 2004


#
# Global default settings:
#
$md_empty_element_suffix = " />";     # Change to ">" for HTML output
$md_tab_width = 4;

#
# WordPress settings:
#
$md_wp_posts    = true;  # Set to false to remove Markdown from posts.
$md_wp_comments = true;  # Set to false to remove Markdown from comments.


# -- WordPress Plugin Interface -----------------------------------------------
/*
Plugin Name: PHP Markdown Extra
Plugin URI: http://www.michelf.com/projects/php-markdown/
Description: <a href="http://daringfireball.net/projects/markdown/syntax">Markdown syntax</a> allows you to write using an easy-to-read, easy-to-write plain text format. Based on the original Perl version by <a href="http://daringfireball.net/">John Gruber</a>. <a href="http://www.michelf.com/projects/php-markdown/">More...</a>
Version: Extra 1.0
Author: Michel Fortin
Author URI: http://www.michelf.com/
*/
if (isset($wp_version)) {
	# More details about how it works here:
	# <http://www.michelf.com/weblog/2005/wordpress-text-flow-vs-markdown/>
	
	# Post content and excerpts
	if ($md_wp_posts) {
		remove_filter('the_content',  'wpautop');
		remove_filter('the_excerpt',  'wpautop');
		add_filter('the_content',     'Markdown', 6);
		add_filter('get_the_excerpt', 'Markdown', 6);
		add_filter('get_the_excerpt', 'trim', 7);
		add_filter('the_excerpt',     'md_add_p');
		add_filter('the_excerpt_rss', 'md_strip_p');
		
		remove_filter('content_save_pre',  'balanceTags', 50);
		remove_filter('excerpt_save_pre',  'balanceTags', 50);
		add_filter('the_content',  	  'balanceTags', 50);
		add_filter('get_the_excerpt', 'balanceTags', 9);
		
		function md_add_p($text) {
			if (strlen($text) == 0) return;
			if (strcasecmp(substr($text, -3), '<p>') == 0) return $text;
			return '<p>'.$text.'</p>';
		}
		function md_strip_p($t) { return preg_replace('{</?[pP]>}', '', $t); }
	}
	
	# Comments
	if ($md_wp_comments) {
		remove_filter('comment_text', 'wpautop');
		remove_filter('comment_text', 'make_clickable');
		add_filter('pre_comment_content', 'Markdown', 6);
		add_filter('pre_comment_content', 'md_hide_tags', 8);
		add_filter('pre_comment_content', 'md_show_tags', 12);
		add_filter('get_comment_text',    'Markdown', 6);
		add_filter('get_comment_excerpt', 'Markdown', 6);
		add_filter('get_comment_excerpt', 'md_strip_p', 7);
	
		global $md_hidden_tags;
		$md_hidden_tags = array(
			'<p>'	=> md5('<p>'),		'</p>'	=> md5('</p>'),
			'<pre>'	=> md5('<pre>'),	'</pre>'=> md5('</pre>'),
			'<ol>'	=> md5('<ol>'),		'</ol>'	=> md5('</ol>'),
			'<ul>'	=> md5('<ul>'),		'</ul>'	=> md5('</ul>'),
			'<li>'	=> md5('<li>'),		'</li>'	=> md5('</li>'),
			);
		
		function md_hide_tags($text) {
			global $md_hidden_tags;
			return str_replace(array_keys($md_hidden_tags), 
								array_values($md_hidden_tags), $text);
		}
		function md_show_tags($text) {
			global $md_hidden_tags;
			return str_replace(array_values($md_hidden_tags), 
								array_keys($md_hidden_tags), $text);
		}
	}
}


# -- bBlog Plugin Info --------------------------------------------------------
function identify_modifier_markdown() {
	global $MarkdownPHPVersion;
	return array(
		'name'			=> 'markdown',
		'type'			=> 'modifier',
		'nicename'		=> 'PHP Markdown Extra',
		'description'	=> 'A text-to-HTML conversion tool for web writers',
		'authors'		=> 'Michel Fortin and John Gruber',
		'licence'		=> 'GPL',
		'version'		=> $MarkdownPHPVersion,
		'help'			=> '<a href="http://daringfireball.net/projects/markdown/syntax">Markdown syntax</a> allows you to write using an easy-to-read, easy-to-write plain text format. Based on the original Perl version by <a href="http://daringfireball.net/">John Gruber</a>. <a href="http://www.michelf.com/projects/php-markdown/">More...</a>'
	);
}

# -- Smarty Modifier Interface ------------------------------------------------
function smarty_modifier_markdown($text) {
	return Markdown($text);
}

# -- Textile Compatibility Mode -----------------------------------------------
# Rename this file to "classTextile.php" and it can replace Textile anywhere.
if (strcasecmp(substr(__FILE__, -16), "classTextile.php") == 0) {
	# Try to include PHP SmartyPants. Should be in the same directory.
	@include_once 'smartypants.php';
	# Fake Textile class. It calls Markdown instead.
	class Textile {
		function TextileThis($text, $lite='', $encode='', $noimage='', $strict='') {
			if ($lite == '' && $encode == '')   $text = Markdown($text);
			if (function_exists('SmartyPants')) $text = SmartyPants($text);
			return $text;
		}
	}
}



#
# Globals:
#

# Regex to match balanced [brackets].
# Needed to insert a maximum bracked depth while converting to PHP.
$md_nested_brackets_depth = 6;
$md_nested_brackets = 
	str_repeat('(?>[^\[\]]+|\[', $md_nested_brackets_depth).
	str_repeat('\])*', $md_nested_brackets_depth);

# Table of hash values for escaped characters:
$md_escape_table = array(
	"\\" => md5("\\"),
	"`" => md5("`"),
	"*" => md5("*"),
	"_" => md5("_"),
	"{" => md5("{"),
	"}" => md5("}"),
	"[" => md5("["),
	"]" => md5("]"),
	"(" => md5("("),
	")" => md5(")"),
	">" => md5(">"),
	"#" => md5("#"),
	"+" => md5("+"),
	"-" => md5("-"),
	"." => md5("."),
	"!" => md5("!"),
	":" => md5(":"),
	"|" => md5("|"),
);
# Create an identical table but for escaped characters.
$md_backslash_escape_table;
foreach ($md_escape_table as $key => $char)
	$md_backslash_escape_table["\\$key"] = $char;



function Markdown($text) {
#
# Main function. The order in which other subs are called here is
# essential. Link and image substitutions need to happen before
# _EscapeSpecialCharsWithinTagAttributes(), so that any *'s or _'s in the <a>
# and <img> tags get encoded.
#
	# Clear the global hashes. If we don't clear these, you get conflicts
	# from other articles when generating a page which contains more than
	# one article (e.g. an index page that shows the N most recent
	# articles):
	global $md_urls, $md_titles, $md_html_blocks, $md_html_hashes;
	$md_urls = array();
	$md_titles = array();
	$md_html_blocks = array();
	$md_html_hashes = array();

	# Standardize line endings:
	#   DOS to Unix and Mac to Unix
	$text = str_replace(array("\r\n", "\r"), "\n", $text);

	# Make sure $text ends with a couple of newlines:
	$text .= "\n\n";

	# Convert all tabs to spaces.
	$text = _Detab($text);

	# Turn block-level HTML blocks into hash entries
	$text = _HashHTMLBlocks($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 /[ \t]*\n+/ .
	$text = preg_replace('/^[ \t]+$/m', '', $text);

	# Strip link definitions, store in hashes.
	$text = _StripLinkDefinitions($text);

	$text = _RunBlockGamut($text, FALSE);

	$text = _UnescapeSpecialChars($text);

	return $text . "\n";
}


function _StripLinkDefinitions($text) {
#
# Strips link definitions from text, stores the URLs and titles in
# hash references.
#
	global $md_tab_width;
	$less_than_tab = $md_tab_width - 1;

	# Link defs are in the form: ^[id]: url "optional title"
	$text = preg_replace_callback('{
						^[ ]{0,'.$less_than_tab.'}\[(.+)\]:	# id = $1
						  [ \t]*
						  \n?				# maybe *one* newline
						  [ \t]*
						<?(\S+?)>?			# url = $2
						  [ \t]*
						  \n?				# maybe one newline
						  [ \t]*
						(?:
							(?<=\s)			# lookbehind for whitespace
							["(]
							(.+?)			# title = $3
							[")]
							[ \t]*
						)?	# title is optional
						(?:\n+|\Z)
		}xm',
		'_StripLinkDefinitions_callback',
		$text);
	return $text;
}
function _StripLinkDefinitions_callback($matches) {
	global $md_urls, $md_titles;
	$link_id = strtolower($matches[1]);
	$md_urls[$link_id] = _EncodeAmpsAndAngles($matches[2]);
	if (isset($matches[3]))
		$md_titles[$link_id] = str_replace('"', '&quot;', $matches[3]);
	return ''; # String that will replace the block
}


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 <p>s around
# "paragraphs" that are wrapped in non-block-level tags, such as anchors,
# phrase emphasis, and spans. The list of tags we're looking for is
# hard-coded.
#
# This works by calling _HashHTMLBlocks_InMarkdown, which then calls
# _HashHTMLBlocks_InHTML when it encounter block tags. When the markdown="1" 
# attribute is found whitin 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!
# 
	global	$block_tags, $context_block_tags, $contain_span_tags, 
			$clean_tags, $auto_close_tags;
	
	# Tags that are always treated as block tags:
	$block_tags = 'p|div|h[1-6]|blockquote|pre|table|dl|ol|ul|'.
					'form|fieldset|iframe|hr|legend';
	
	# Tags treated as block tags only if the opening tag is alone on it's line:
	$context_block_tags = 'script|noscript|math|ins|del';
	
	# Tags where markdown="1" default to span mode:
	$contain_span_tags = 'p|h[1-6]|li|dd|dt|td|th|legend';
	
	# Tags which must not have their contents modified, no matter where 
	# they appear:
	$clean_tags = 'script|math';
	
	# Tags that do not need to be closed.
	$auto_close_tags = 'hr|img';
	
	# Regex to match any tag.
	global $tag_match;
	$tag_match =
		'{
			(					# $2: Capture hole tag.
				</?					# Any opening or closing tag.
					[\w:$]+			# Tag name.
					\s*				# Whitespace.
					(?:
						".*?"		|	# Double quotes (can contain `>`)
						\'.*?\'   	|	# Single quotes (can contain `>`)
						.+?				# Anything but quotes and `>`.
					)*?
				>					# End of tag.
			|
				<!--    .*?     -->	# HTML Comment
			|
				<\?     .*?     \?>	# Processing instruction
			|
				<!\[CDATA\[.*?\]\]>	# CData Block
			)
		}xs';
	
	#
	# Call the HTML-in-Markdown hasher.
	#
	list($text, ) = _HashHTMLBlocks_InMarkdown($text);
	
	return $text;
}
function _HashHTMLBlocks_InMarkdown($text, $indent = 0, 
									$enclosing_tag = '', $md_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:
#
#     <div>
#         <div markdown="1">
#         Hello World.  <-- Is this a Markdown code block or text?
#         </div>  <-- Is this a Markdown code block or a real tag?
#     <div>
#
#     If you don't like this, just don't indent the tag on which
#     you apply the markdown="1" attribute.
#
# *   If $enclosing_tag is not empty, stops at the first unmatched closing 
#     tag with that name. Nested tags supported.
#
# *   If $md_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 )
#
	global	$block_tags, $context_block_tags, $clean_tags, $auto_close_tags,
			$tag_match;
	
	if ($text === '') return array('', '');

	# Regex to check for the presense of newlines around a block tag.
	$newline_match_before = "/(?:^\n?|\n\n) *$/";
	$newline_match_after = 
		'{
			^						# Start of text following the tag.
			(?:[ ]*<!--.*?-->)?		# Optional comment.
			[ ]*\n					# Must be followed by newline.
		}xs';
	
	# Regex to match any tag.
	$block_tag_match =
		'{
			(					# $2: Capture hole tag.
				</?					# Any opening or closing tag.
					(?:				# Tag name.
						'.$block_tags.'			|
						'.$context_block_tags.'	|
						'.$clean_tags.'        	|
						(?!\s)'.$enclosing_tag.'
					)
					\s*				# Whitespace.
					(?:
						".*?"		|	# Double quotes (can contain `>`)
						\'.*?\'   	|	# Single quotes (can contain `>`)
						.+?				# Anything but quotes and `>`.
					)*?
				>					# End of tag.
			|
				<!--    .*?     -->	# HTML Comment
			|
				<\?     .*?     \?>	# Processing instruction
			|
				<!\[CDATA\[.*?\]\]>	# CData Block
			)
		}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_match, $text, 2, 
							PREG_SPLIT_DELIM_CAPTURE);
		
		# If in Markdown span mode, replace any multiple newlines that would 
		# trigger a new paragraph.
		if ($md_span) {
			$parts[0] = preg_replace('/\n\n/', "\n", $parts[0]);
		}
		
		$parsed .= $parts[0]; # Text before current tag.
		
		# If end of $text has been reached. Stop loop.
		if (count($parts) < 3) {
			$text = "";
			break;
		}
		
		$tag  = $parts[1]; # Tag to handle.
		$text = $parts[2]; # Remaining text after current tag.
		
		#
		# Check for: Tag inside code block or span
		#
		if (# Find current paragraph
			preg_match('/(?>^\n?|\n\n)((?>.\n?)+?)$/', $parsed, $matches) &&
			(
			# Then match in it either a code block...
			preg_match('/^ {'.($indent+4).'}.*(?>\n {'.($indent+4).'}.*)*'.
						'(?!\n)$/', $matches[1], $x) ||
			# ...or unbalenced code span markers. (the regex matches balenced)
			!preg_match('/^(?>[^`]+|(`+)(?>[^`]+|(?!\1[^`])`)*?\1(?!`))*$/s',
						 $matches[1])
			))
		{
			# Tag is in code block or span and may not be a tag at all. So we
			# simply skip the first char (should be a `<`).
			$parsed .= $tag{0};
			$text = substr($tag, 1) . $text; # Put back $tag minus first char.
		}
		#
		# Check for: Opening Block level tag or
		#            Opening Content Block tag (like ins and del) 
		#               used as a block tag (tag is alone on it's line).
		#
		else if (preg_match("{^<(?:$block_tags)\b}", $tag) ||
			(	preg_match("{^<(?:$context_block_tags)\b}", $tag) &&
				preg_match($newline_match_before, $parsed) &&
				preg_match($newline_match_after, $text)	)
			)
		{
			# Need to parse tag and following text using the HTML parser.
			list($block_text, $text) = 
				_HashHTMLBlocks_InHTML($tag . $text,
									"_HashHTMLBlocks_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("{^<(?:$clean_tags)\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, $text) = 
				_HashHTMLBlocks_InHTML($tag . $text, 
									"_HashHTMLBlocks_HashClean", FALSE);
			
			$parsed .= $block_text;
		}
		#
		# Check for: Tag with same name as enclosing tag.
		#
		else if ($enclosing_tag !== '' &&
			# Same name as enclosing tag.
			preg_match("{^</?(?:$enclosing_tag)\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, $text);
}
function _HashHTMLBlocks_InHTML($text, $hash_function, $md_attr) {
#
# Parse HTML, calling _HashHTMLBlocks_InMarkdown for block tags.
#
# *   Calls $hash_function 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 )
#
	global $auto_close_tags, $contain_span_tags, $tag_match;
	
	if ($text === '') return array('', '');
	
	# Regex to match `markdown` attribute inside of a tag.
	$markdown_attr_match = '
		{
			\s*			# Eat whitespace before the `markdown` attribute
			markdown
			\s*=\s*
			(["\'])		# $1: quote delimiter		
			(.*?)		# $2: attribute value
			\1			# matching delimiter	
		}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.
	#
	if (preg_match("/^<([\w:$]*)\b/", $text, $matches))
		$base_tag_name = $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_match, $text, 2, PREG_SPLIT_DELIM_CAPTURE);
		
		if (count($parts) < 3) {
			#
			# End of $text reached with unbalenced tag(s).
			# In that case, we return original text unchanged and pass the
			# first character as filtered to prevent an infinite loop in the 
			# parent function.
			#
			return array($original_text{0}, substr($original_text, 1));
		}
		
		$block_text .= $parts[0]; # Text before current tag.
		$tag         = $parts[1]; # Tag to handle.
		$text        = $parts[2]; # Remaining text after current tag.
		
		#
		# Check for: Auto-close tag (like <hr/>)
		#			 Comments and Processing Instructions.
		#
		if (preg_match("{^</?(?:$auto_close_tags)\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\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_match, $tag, $attr_matches) &&
				preg_match('/^(?:1|block|span)$/', $attr_matches[2]))
			{
				# Remove `markdown` attribute from opening tag.
				$tag = preg_replace($markdown_attr_match, '', $tag);
				
				# Check if text inside this tag must be parsed in span mode.
				$md_mode = $attr_matches[2];
				$span_mode = $md_mode == 'span' || $md_mode != 'block' &&
							preg_match("{^<(?:$contain_span_tags)\b}", $tag);
				
				# Calculate indent before tag.
				preg_match('/(?:^|\n)( *?)(?! ).*?$/', $block_text, $matches);
				$indent = strlen($matches[1]);
				
				# End preceding block with this tag.
				$block_text .= $tag;
				$parsed .= $hash_function($block_text, $span_mode);
				
				# Get enclosing tag name for the ParseMarkdown function.
				preg_match('/^<([\w:$]*)\b/', $tag, $matches);
				$tag_name = $matches[1];
				
				# Parse the content using the HTML-in-Markdown parser.
				list ($block_text, $text)
					= _HashHTMLBlocks_InMarkdown($text, $indent, 
													$tag_name, $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 a new block.
				$block_text = "";
			}
			else $block_text .= $tag;
		}
		
	} while ($depth > 0);
	
	#
	# Hash last block text that wasn't processed inside the loop.
	#
	$parsed .= $hash_function($block_text);
	
	return array($parsed, $text);
}
function _HashHTMLBlocks_HashBlock($text) {
	global $md_html_hashes, $md_html_blocks;
	$key = md5($text);
	$md_html_hashes[$key] = $text;
	$md_html_blocks[$key] = $text;
	return $key; # String that will replace the tag.
}
function _HashHTMLBlocks_HashClean($text) {
	global $md_html_hashes;
	$key = md5($text);
	$md_html_hashes[$key] = $text;
	return $key; # String that will replace the clean tag.
}


function _HashBlock($text) {
#
# Called whenever a tag must be hashed. When a function insert a block-level 
# tag in $text, it pass through this function and is automaticaly escaped, 
# which remove the need to call _HashHTMLBlocks at every step.
#
	# Swap back any tag hash found in $text so we do not have to _UnhashTags
	# multiple times at the end. Must do this because of 
	$text = _UnhashTags($text);
	
	# Then hash the block as normal.
	return _HashHTMLBlocks_HashBlock($text);
}


function _RunBlockGamut($text, $hash_html_blocks = TRUE) {
#
# These are all the transformations that form block-level
# tags like paragraphs, headers, and list items.
#
	if ($hash_html_blocks) {
		# 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
		# a list item and could have been indented. Indented blocks would have 
		# been seen as a code block in previous pass of _HashHTMLBlocks.
		$text = _HashHTMLBlocks($text);
	}

	$text = _DoHeaders($text);
	$text = _DoTables($text);

	# Do Horizontal Rules:
	global $md_empty_element_suffix;
	$text = preg_replace(
		array('{^[ ]{0,2}([ ]?\*[ ]?){3,}[ \t]*$}emx',
			  '{^[ ]{0,2}([ ]? -[ ]?){3,}[ \t]*$}emx',
			  '{^[ ]{0,2}([ ]? _[ ]?){3,}[ \t]*$}emx'),
		"_HashBlock('\n<hr$md_empty_element_suffix\n')", 
		$text);

	$text = _DoLists($text);
	$text = _DoDefLists($text);
	$text = _DoCodeBlocks($text);
	$text = _DoBlockQuotes($text);
	$text = _FormParagraphs($text);

	return $text;
}


function _RunSpanGamut($text) {
#
# These are all the transformations that occur *within* block-level
# tags like paragraphs, headers, and list items.
#
	global $md_empty_element_suffix;

	$text = _DoCodeSpans($text);

	$text = _EscapeSpecialChars($text);

	# Process anchor and image tags. Images must come first,
	# because ![foo][f] looks like an anchor.
	$text = _DoImages($text);
	$text = _DoAnchors($text);

	# 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>).
	$text = _DoAutoLinks($text);
	$text = _EncodeAmpsAndAngles($text);
	$text = _DoItalicsAndBold($text);

	# Do hard breaks:
	$text = preg_replace('/ {2,}\n/', "<br$md_empty_element_suffix\n", $text);

	return $text;
}


function _EscapeSpecialChars($text) {
	global $md_escape_table;
	$tokens = _TokenizeHTML($text);

	$text = '';   # rebuild $text from the tokens
#	$in_pre = 0;  # Keep track of when we're inside <pre> or <code> tags.
#	$tags_to_skip = "!<(/?)(?:pre|code|kbd|script|math)[\s>]!";

	foreach ($tokens as $cur_token) {
		if ($cur_token[0] == 'tag') {
			# Within tags, encode * and _ so they don't conflict
			# with their use in Markdown for italics and strong.
			# We're replacing each such character with its
			# corresponding MD5 checksum value; this is likely
			# overkill, but it should prevent us from colliding
			# with the escape values by accident.
			$cur_token[1] = str_replace(array('*', '_'),
				array($md_escape_table['*'], $md_escape_table['_']),
				$cur_token[1]);
			$text .= $cur_token[1];
		} else {
			$t = $cur_token[1];
			$t = _EncodeBackslashEscapes($t);
			$text .= $t;
		}
	}
	return $text;
}


function _DoAnchors($text) {
#
# Turn Markdown link shortcuts into XHTML <a> tags.
#
	global $md_nested_brackets;
	#
	# First, handle reference-style links: [link text] [id]
	#
	$text = preg_replace_callback("{
		(					# wrap whole match in $1
		  \\[
			($md_nested_brackets)	# link text = $2
		  \\]

		  [ ]?				# one optional space
		  (?:\\n[ ]*)?		# one optional newline followed by spaces

		  \\[
			(.*?)		# id = $3
		  \\]
		)
		}xs",
		'_DoAnchors_reference_callback', $text);

	#
	# Next, inline-style links: [link text](url "optional title")
	#
	$text = preg_replace_callback("{
		(				# wrap whole match in $1
		  \\[
			($md_nested_brackets)	# link text = $2
		  \\]
		  \\(			# literal paren
			[ \\t]*
			<?(.*?)>?	# href = $3
			[ \\t]*
			(			# $4
			  (['\"])	# quote char = $5
			  (.*?)		# Title = $6
			  \\5		# matching quote
			)?			# title is optional
		  \\)
		)
		}xs",
		'_DoAnchors_inline_callback', $text);

	return $text;
}
function _DoAnchors_reference_callback($matches) {
	global $md_urls, $md_titles, $md_escape_table;
	$whole_match = $matches[1];
	$link_text   = $matches[2];
	$link_id     = strtolower($matches[3]);

	if ($link_id == "") {
		$link_id = strtolower($link_text); # for shortcut links like [this][].
	}

	if (isset($md_urls[$link_id])) {
		$url = $md_urls[$link_id];
		# We've got to encode these to avoid conflicting with italics/bold.
		$url = str_replace(array('*', '_'),
						   array($md_escape_table['*'], $md_escape_table['_']),
						   $url);
		$result = "<a href=\"$url\"";
		if ( isset( $md_titles[$link_id] ) ) {
			$title = $md_titles[$link_id];
			$title = str_replace(array('*',     '_'),
								 array($md_escape_table['*'], 
									   $md_escape_table['_']), $title);
			$result .=  " title=\"$title\"";
		}
		$result .= ">$link_text</a>";
	}
	else {
		$result = $whole_match;
	}
	return $result;
}
function _DoAnchors_inline_callback($matches) {
	global $md_escape_table;
	$whole_match	= $matches[1];
	$link_text		= $matches[2];
	$url			= $matches[3];
	$title			=& $matches[6];

	# We've got to encode these to avoid conflicting with italics/bold.
	$url = str_replace(array('*', '_'),
					   array($md_escape_table['*'], $md_escape_table['_']), 
					   $url);
	$result = "<a href=\"$url\"";
	if (isset($title)) {
		$title = str_replace('"', '&quot;', $title);
		$title = str_replace(array('*', '_'),
							 array($md_escape_table['*'], $md_escape_table['_']),
							 $title);
		$result .=  " title=\"$title\"";
	}
	
	$result .= ">$link_text</a>";

	return $result;
}


function _DoImages($text) {
#
# Turn Markdown image shortcuts into <img> tags.
#
	global $md_nested_brackets;

	#
	# First, handle reference-style labeled images: ![alt text][id]
	#
	$text = preg_replace_callback('{
		(				# wrap whole match in $1
		  !\[
			('.$md_nested_brackets.')		# alt text = $2
		  \]

		  [ ]?				# one optional space
		  (?:\n[ ]*)?		# one optional newline followed by spaces

		  \[
			(.*?)		# id = $3
		  \]

		)
		}xs', 
		'_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
		  !\[
			('.$md_nested_brackets.')		# alt text = $2
		  \]
		  \(			# literal paren
			[ \t]*
			<?(\S+?)>?	# src url = $3
			[ \t]*
			(			# $4
			  ([\'"])	# quote char = $5
			  (.*?)		# title = $6
			  \5		# matching quote
			  [ \t]*
			)?			# title is optional
		  \)
		)
		}xs',
		'_DoImages_inline_callback', $text);

	return $text;
}
function _DoImages_reference_callback($matches) {
	global $md_urls, $md_titles, $md_empty_element_suffix, $md_escape_table;
	$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 = str_replace('"', '&quot;', $alt_text);
	if (isset($md_urls[$link_id])) {
		$url = $md_urls[$link_id];
		# We've got to encode these to avoid conflicting with italics/bold.
		$url = str_replace(array('*', '_'),
						   array($md_escape_table['*'], $md_escape_table['_']),
						   $url);
		$result = "<img src=\"$url\" alt=\"$alt_text\"";
		if (isset($md_titles[$link_id])) {
			$title = $md_titles[$link_id];
			$title = str_replace(array('*', '_'),
								 array($md_escape_table['*'], 
									   $md_escape_table['_']), $title);
			$result .=  " title=\"$title\"";
		}
		$result .= $md_empty_element_suffix;
	}
	else {
		# If there's no such link ID, leave intact:
		$result = $whole_match;
	}

	return $result;
}
function _DoImages_inline_callback($matches) {
	global $md_empty_element_suffix, $md_escape_table;
	$whole_match	= $matches[1];
	$alt_text		= $matches[2];
	$url			= $matches[3];
	$title			= '';
	if (isset($matches[6])) {
		$title		= $matches[6];
	}

	$alt_text = str_replace('"', '&quot;', $alt_text);
	$title    = str_replace('"', '&quot;', $title);
	# We've got to encode these to avoid conflicting with italics/bold.
	$url = str_replace(array('*', '_'),
					   array($md_escape_table['*'], $md_escape_table['_']),
					   $url);
	$result = "<img src=\"$url\" alt=\"$alt_text\"";
	if (isset($title)) {
		$title = str_replace(array('*', '_'),
							 array($md_escape_table['*'], $md_escape_table['_']),
							 $title);
		$result .=  " title=\"$title\""; # $title already quoted
	}
	$result .= $md_empty_element_suffix;

	return $result;
}


function _DoHeaders($text) {
	# Setext-style headers:
	#	  Header 1
	#	  ========
	#  
	#	  Header 2
	#	  --------
	#
	$text = preg_replace(
		array('{ (^.+?) (?:[ ]+\{\#([-_:a-zA-Z0-9]+)\})? [ \t]*\n=+[ \t]*\n+ }emx',
			  '{ (^.+?) (?:[ ]+\{\#([-_:a-zA-Z0-9]+)\})? [ \t]*\n-+[ \t]*\n+ }emx'),
		array("_HashBlock('<h1'. ('\\2'? ' id=\"'._UnslashQuotes('\\2').'\"':'').
				'>'._RunSpanGamut(_UnslashQuotes('\\1')).'</h1>'
			  ) . '\n\n'",
			  "_HashBlock('<h2'. ('\\2'? ' id=\"'._UnslashQuotes('\\2').'\"':'').
				'>'._RunSpanGamut(_UnslashQuotes('\\1')).'</h2>'
			  ) . '\n\n'"),
		$text);

	# atx-style headers:
	#	# Header 1
	#	## Header 2
	#	## Header 2 with closing hashes ##
	#	...
	#	###### Header 6
	#
	$text = preg_replace('{
			^(\#{1,6})	# $1 = string of #\'s
			[ \t]*
			(.+?)		# $2 = Header text
			[ \t]*
			\#*			# optional closing #\'s (not counted)
			(?:[ ]+\{\#([-_:a-zA-Z0-9]+)\}[ ]*)? # id attribute
			\n+
		}xme',
		"_HashBlock(
			'<h'.strlen('\\1'). ('\\3'? ' id=\"'._UnslashQuotes('\\3').'\"':'').'>'.
			_RunSpanGamut(_UnslashQuotes('\\2')).
			'</h'.strlen('\\1').'>'
		) . '\n\n'",
		$text);

	return $text;
}


function _DoTables($text) {
#
# Form HTML tables.
#
	global $md_tab_width;
	$less_than_tab = $md_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',
		'_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',
		'_DoTable_callback', $text);

	return $text;
}
function _DoTable_LeadingPipe_callback($matches) {
	$head		= $matches[1];
	$underline	= $matches[2];
	$content	= $matches[3];
	
	# Remove leading pipe for each row.
	$content	= preg_replace('/^ *[|]/m', '', $content);
	
	return _DoTable_callback(array($matches[0], $head, $underline, $content));
}
function _DoTable_callback($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] = ' align="right"';
		else if (preg_match('/^ *:-+: *$/', $s))$attr[$n] = ' align="center"';
		else if (preg_match('/^ *:-+ *$/', $s))	$attr[$n] = ' align="left"';
		else									$attr[$n] = '';
	}
	
	# Creating code spans before splitting the row is an easy way to 
	# handle a code span containg pipes.
	$head	= _DoCodeSpans($head);
	$headers	= preg_split('/ *[|] */', $head);
	$col_count	= count($headers);
	
	# Write column headers.
	$text = "<table>\n";
	$text .= "<thead>\n";
	$text .= "<tr>\n";
	foreach ($headers as $n => $header)
		$text .= "  <th$attr[$n]>"._RunSpanGamut(trim($header))."</th>\n";
	$text .= "</tr>\n";
	$text .= "</thead>\n";
	
	# Split content by row.
	$rows = explode("\n", trim($content, "\n"));
	
	$text .= "<tbody>\n";
	foreach ($rows as $row) {
		# Creating code spans before splitting the row is an easy way to 
		# handle a code span containg pipes.
		$row = _DoCodeSpans($row);
		
		# Split row by cell.
		$row_cells = preg_split('/ *[|] */', $row, $col_count);
		$row_cells = array_pad($row_cells, $col_count, '');
		
		$text .= "<tr>\n";
		foreach ($row_cells as $n => $cell)
			$text .= "  <td$attr[$n]>"._RunSpanGamut(trim($cell))."</td>\n";
		$text .= "</tr>\n";
	}
	$text .= "</tbody>\n";
	$text .= "</table>";
	
	return _HashBlock($text) . "\n";
}


function _DoLists($text) {
#
# Form HTML ordered (numbered) and unordered (bulleted) lists.
#
	global $md_tab_width, $md_list_level;
	$less_than_tab = $md_tab_width - 1;

	# Re-usable patterns to match list item bullets and number markers:
	$marker_ul  = '[*+-]';
	$marker_ol  = '\d+[.]';
	$marker_any = "(?:$marker_ul|$marker_ol)";

	$markers = array($marker_ul, $marker_ol);

	foreach ($markers as $marker) {
		# Re-usable pattern to match any entirel ul or ol list:
		$whole_list = '
			(								# $1 = whole list
			  (								# $2
				[ ]{0,'.$less_than_tab.'}
				('.$marker.')				# $3 = first list item marker
				[ \t]+
			  )
			  (?s:.+?)
			  (								# $4
				  \z
				|
				  \n{2,}
				  (?=\S)
				  (?!						# Negative lookahead for another list item marker
					[ \t]*
					'.$marker.'[ \t]+
				  )
			  )
			)
		'; // mx
		
		# We use a different prefix before nested lists than top-level lists.
		# See extended comment in _ProcessListItems().
	
		if ($md_list_level) {
			$text = preg_replace_callback('{
					^
					'.$whole_list.'
				}mx',
				'_DoLists_callback', $text);
		}
		else {
			$text = preg_replace_callback('{
					(?:(?<=\n\n)|\A\n?)
					'.$whole_list.'
				}mx',
				'_DoLists_callback', $text);
		}
	}

	return $text;
}
function _DoLists_callback($matches) {
	# Re-usable patterns to match list item bullets and number markers:
	$marker_ul  = '[*+-]';
	$marker_ol  = '\d+[.]';
	$marker_any = "(?:$marker_ul|$marker_ol)";
	
	$list = $matches[1];
	$list_type = preg_match("/$marker_ul/", $matches[3]) ? "ul" : "ol";
	
	$marker_any = ( $list_type == "ul" ? $marker_ul : $marker_ol );
	
	# Turn double returns into triple returns, so that we can make a
	# paragraph for the last item in a list, if necessary:
	$list = preg_replace("/\n{2,}/", "\n\n\n", $list);
	$result = _ProcessListItems($list, $marker_any);
	$result = "<$list_type>\n" . $result . "</$list_type>";
	return "\n" . _HashBlock($result) . "\n\n";
}


function _ProcessListItems($list_str, $marker_any) {
#
#	Process the contents of a single ordered or unordered list, splitting it
#	into individual list items.
#
	global $md_list_level;
	
	# The $md_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.".
	
	$md_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
		(^[ \t]*)						# leading whitespace = $2
		('.$marker_any.') [ \t]+		# list marker = $3
		((?s:.+?)						# list item text   = $4
		(\n{1,2}))
		(?= \n* (\z | \2 ('.$marker_any.') [ \t]+))
		}xm',
		'_ProcessListItems_callback', $list_str);

	$md_list_level--;
	return $list_str;
}
function _ProcessListItems_callback($matches) {
	$item = $matches[4];
	$leading_line =& $matches[1];
	$leading_space =& $matches[2];

	if ($leading_line || preg_match('/\n{2,}/', $item)) {
		$item = _RunBlockGamut(_Outdent($item));
	}
	else {
		# Recursion for sub-lists:
		$item = _DoLists(_Outdent($item));
		$item = preg_replace('/\n+$/', '', $item);
		$item = _RunSpanGamut($item);
	}

	return "<li>" . $item . "</li>\n";
}


function _DoDefLists($text) {
#
# Form HTML definition lists.
#
	global $md_tab_width;
	$less_than_tab = $md_tab_width - 1;

	# Re-usable patterns to match list item bullets and number markers:

	# Re-usable pattern to match any entire dl list:
	$whole_list = '
		(								# $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

	$text = preg_replace_callback('{
			(?:(?<=\n\n)|\A\n?)
			'.$whole_list.'
		}mx',
		'_DoDefLists_callback', $text);

	return $text;
}
function _DoDefLists_callback($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:
	$result = trim(_ProcessDefListItems($list));
	$result = "<dl>\n" . $result . "\n</dl>";
	return _HashBlock($result) . "\n\n";
}


function _ProcessDefListItems($list_str) {
#
#	Process the contents of a single ordered or unordered list, splitting it
#	into individual list items.
#
	global $md_tab_width;
	$less_than_tab = $md_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('{
		(?:\n\n+|\A\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',
		'_ProcessDefListItems_callback_dt', $list_str);

	# Process actual definitions.
	$list_str = preg_replace_callback('{
		\n(\n+)?						# leading line = $1
		[ ]{0,'.$less_than_tab.'}		# whitespace before colon
		[:][ ]+							# definition mark (colon)
		((?s:.+?))						# definition text = $2
		(?= \n+ 						# stop at next definition mark,
			(?:							# next term or end of text
				[ ]{0,'.$less_than_tab.'} [:][ ]	|
				<dt> | \z
			)						
		)					
		}xm',
		'_ProcessDefListItems_callback_dd', $list_str);

	return $list_str;
}
function _ProcessDefListItems_callback_dt($matches) {
	$terms = explode("\n", trim($matches[1]));
	$text = '';
	foreach ($terms as $term) {
		$term = _RunSpanGamut(trim($term));
		$text .= "\n<dt>" . $term . "</dt>";
	}
	return $text . "\n";
}
function _ProcessDefListItems_callback_dd($matches) {
	$leading_line	= $matches[1];
	$def			= $matches[2];

	if ($leading_line || preg_match('/\n{2,}/', $def)) {
		$def = _RunBlockGamut(_Outdent($def . "\n\n"));
		$def = "\n". $def ."\n";
	}
	else {
		$def = rtrim($def);
		$def = _RunSpanGamut(_Outdent($def));
	}

	return "\n<dd>" . $def . "</dd>\n";
}


function _DoCodeBlocks($text) {
#
#	Process Markdown `<pre><code>` blocks.
#
	global $md_tab_width;
	$text = preg_replace_callback("{
			(?:\\n\\n|\\A)
			(	            # $1 = the code block -- one or more lines, starting with a space/tab
			  (?:
				(?:[ ]\{$md_tab_width} | \\t)  # Lines must start with a tab or a tab-width of spaces
				.*\\n+
			  )+
			)
			((?=^[ ]{0,$md_tab_width}\\S)|\\Z)	# Lookahead for non-space at line-start, or end of doc
		}xm",
		'_DoCodeBlocks_callback', $text);

	return $text;
}
function _DoCodeBlocks_callback($matches) {
	$codeblock = $matches[1];

	$codeblock = _EncodeCode(_Outdent($codeblock));
//	$codeblock = _Detab($codeblock);
	# trim leading newlines and trailing whitespace
	$codeblock = preg_replace(array('/\A\n+/', '/\s+\z/'), '', $codeblock);

	$result = "<pre><code>" . $codeblock . "\n</code></pre>";

	return "\n\n" . _HashBlock($result) . "\n\n";
}


function _DoCodeSpans($text) {
#
# 	*	Backtick quotes are used for <code></code> spans.
#
# 	*	You can use multiple backticks as the delimiters if you want to
# 		include literal backticks in the code span. So, this input:
#
#		  Just type ``foo `bar` baz`` at the prompt.
#
#	  	Will translate to:
#
#		  <p>Just type <code>foo `bar` baz</code> at the prompt.</p>
#
#		There's no arbitrary limit to the number of backticks you
#		can use as delimters. If you need three consecutive backticks
#		in your code, use four for delimiters, etc.
#
#	*	You can use spaces to get literal backticks at the edges:
#
#		  ... type `` `bar` `` ...
#
#	  	Turns to:
#
#		  ... type <code>`bar`</code> ...
#
	$text = preg_replace_callback('@
			(?<!\\\)	# Character before opening ` can\'t be a backslash
			(`+)		# $1 = Opening run of `
			(.+?)		# $2 = The code block
			(?<!`)
			\1			# Matching closer
			(?!`)
		@xs',
		'_DoCodeSpans_callback', $text);

	return $text;
}
function _DoCodeSpans_callback($matches) {
	$c = $matches[2];
	$c = preg_replace('/^[ \t]*/', '', $c); # leading whitespace
	$c = preg_replace('/[ \t]*$/', '', $c); # trailing whitespace
	$c = _EncodeCode($c);
	return "<code>$c</code>";
}


function _EncodeCode($_) {
#
# Encode/escape certain characters inside Markdown code runs.
# The point is that in code, these characters are literals,
# and lose their special Markdown meanings.
#
	global $md_escape_table;

	# Encode all ampersands; HTML entities are not
	# entities within a Markdown code span.
	$_ = str_replace('&', '&amp;', $_);

	# Do the angle bracket song and dance:
	$_ = str_replace(array('<',    '>'), 
					 array('&lt;', '&gt;'), $_);

	# Now, escape characters that are magic in Markdown:
	$_ = str_replace(array_keys($md_escape_table), 
					 array_values($md_escape_table), $_);

	return $_;
}


function _DoItalicsAndBold($text) {
	# <strong> must go first:
	$text = preg_replace(array(
		'{
			( (?<!\w) __ )			# $1: Marker (not preceded by alphanum)
			(?=\S) 					# Not followed by whitespace 
			(?!__)					#   or two others marker chars.
			(						# $2: Content
				(?>
					[^_]+?			# Anthing not em markers.
				|
									# Balence any regular _ emphasis inside.
					(?<![a-zA-Z0-9])_ (?=\S) (?! _) (.+?) 
					(?<=\S) _ (?![a-zA-Z0-9])
				)+?
			)
			(?<=\S) __				# End mark not preceded by whitespace.
			(?!\w)					# Not followed by alphanum.
		}sx',
		'{
			( (?<!\*\*) \*\* )		# $1: Marker (not preceded by two *)
			(?=\S) 					# Not followed by whitespace 
			(?!\1)					#   or two others marker chars.
			(						# $2: Content
				(?>
					[^*]+?			# Anthing not em markers.
				|
									# Balence any regular * emphasis inside.
					\* (?=\S) (?! \*) (.+?) (?<=\S) \*
				)+?
			)
			(?<=\S) \*\*			# End mark not preceded by whitespace.
		}sx',
		),
		'<strong>\2</strong>', $text);
	# Then <em>:
	$text = preg_replace(array(
		'{ ( (?<!\w) _ ) (?=\S) (?! _)  (.+?) (?<=\S) _ (?!\w) }sx',
		'{ ( (?<!\*)\* ) (?=\S) (?! \*) (.+?) (?<=\S) \* }sx',
		),
		'<em>\2</em>', $text);

	return $text;
}


function _DoBlockQuotes($text) {
	$text = preg_replace_callback('/
		  (								# Wrap whole match in $1
			(
			  ^[ \t]*>[ \t]?			# ">" at the start of a line
				.+\n					# rest of the first line
			  (.+\n)*					# subsequent consecutive lines
			  \n*						# blanks
			)+
		  )
		/xm',
		'_DoBlockQuotes_callback', $text);

	return $text;
}
function _DoBlockQuotes_callback($matches) {
	$bq = $matches[1];
	# trim one level of quoting - trim whitespace-only lines
	$bq = preg_replace(array('/^[ \t]*>[ \t]?/m', '/^[ \t]+$/m'), '', $bq);
	$bq = _RunBlockGamut($bq);		# recurse

	$bq = preg_replace('/^/m', "  ", $bq);
	# These leading spaces screw with <pre> content, so we need to fix that:
	$bq = preg_replace_callback('{(\s*<pre>.+?</pre>)}sx', 
								'_DoBlockQuotes_callback2', $bq);

	return _HashBlock("<blockquote>\n$bq\n</blockquote>") . "\n\n";
}
function _DoBlockQuotes_callback2($matches) {
	$pre = $matches[1];
	$pre = preg_replace('/^  /m', '', $pre);
	return $pre;
}


function _FormParagraphs($text) {
#
#	Params:
#		$text - string to process with html <p> tags
#
	global $md_html_blocks, $md_html_hashes;

	# Strip leading and trailing lines:
	$text = preg_replace(array('/\A\n+/', '/\n+\z/'), '', $text);
	
	$grafs = preg_split('/\n{2,}/', $text, -1, PREG_SPLIT_NO_EMPTY);

	#
	# Wrap <p> tags and unhashify HTML blocks
	#
	foreach ($grafs as $key => $value) {
		$value = trim(_RunSpanGamut($value));
		
		# Check if this should be enclosed in a paragraph.
		# Text equaling to a clean tag hash are not enclosed.
		# Text starting with a block tag hash are not either.
		$clean_key = $value;
		$block_key = substr($value, 0, 32);
		
		$is_p = (!isset($md_html_blocks[$block_key]) && 
				 !isset($md_html_hashes[$clean_key]));
		
		if ($is_p) {
			$value = "<p>$value</p>";
		}
		$grafs[$key] = $value;
	}
	
	# Join grafs in one text, then unhash HTML tags. 
	$text = implode("\n\n", $grafs);
	
	# Finish by removing any tag hashes still present in $text.
	$text = _UnhashTags($text);
	
	return $text;
}


function _EncodeAmpsAndAngles($text) {
# Smart processing for ampersands and angle brackets that need to be encoded.

	# Ampersand-encoding based entirely on Nat Irons's Amputator MT plugin:
	#   http://bumppo.net/projects/amputator/
	$text = preg_replace('/&(?!#?[xX]?(?:[0-9a-fA-F]+|\w+);)/', 
						 '&amp;', $text);;

	# Encode naked <'s
	$text = preg_replace('{<(?![a-z/?\$!])}i', '&lt;', $text);

	return $text;
}


function _EncodeBackslashEscapes($text) {
#
#	Parameter:  String.
#	Returns:    The string, with after processing the following backslash
#				escape sequences.
#
	global $md_escape_table, $md_backslash_escape_table;
	# Must process escaped backslashes first.
	return str_replace(array_keys($md_backslash_escape_table),
					   array_values($md_backslash_escape_table), $text);
}


function _DoAutoLinks($text) {
	$text = preg_replace("!<((https?|ftp):[^'\">\\s]+)>!", 
						 '<a href="\1">\1</a>', $text);

	# Email addresses: <address@domain.foo>
	$text = preg_replace('{
		<
        (?:mailto:)?
		(
			[-.\w]+
			\@
			[-a-z0-9]+(\.[-a-z0-9]+)*\.[a-z]+
		)
		>
		}exi',
		"_EncodeEmailAddress(_UnescapeSpecialChars(_UnslashQuotes('\\1')))",
		$text);

	return $text;
}


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.:
#
#	  <a href="&#x6D;&#97;&#105;&#108;&#x74;&#111;:&#102;&#111;&#111;&#64;&#101;
#		x&#x61;&#109;&#x70;&#108;&#x65;&#x2E;&#99;&#111;&#109;">&#102;&#111;&#111;
#		&#64;&#101;x&#x61;&#109;&#x70;&#108;&#x65;&#x2E;&#99;&#111;&#109;</a>
#
#	Based by a filter by Matthew Wickline, posted to the BBEdit-Talk
#	mailing list: <http://tinyurl.com/yu7ue>
#
	$addr = "mailto:" . $addr;
	$length = strlen($addr);

	# leave ':' alone (to spot mailto: later)
	$addr = preg_replace_callback('/([^\:])/', 
								  '_EncodeEmailAddress_callback', $addr);

	$addr = "<a href=\"$addr\">$addr</a>";
	# strip the mailto: from the visible part
	$addr = preg_replace('/">.+?:/', '">', $addr);

	return $addr;
}
function _EncodeEmailAddress_callback($matches) {
	$char = $matches[1];
	$r = rand(0, 100);
	# roughly 10% raw, 45% hex, 45% dec
	# '@' *must* be encoded. I insist.
	if ($r > 90 && $char != '@') return $char;
	if ($r < 45) return '&#x'.dechex(ord($char)).';';
	return '&#'.ord($char).';';
}


function _UnescapeSpecialChars($text) {
#
# Swap back in all the spe…