--------------------------------------------------------------------------------------------- */
		//e.g.	~~~>			or	~~~ PHP ~~~>		(with optional language)
		//	code goes here			code goes here
		//	<~~~				<~~~
		'PRE'	=> '/~~~(?: ([a-z]+) ~~~)?>\n((?>(?R)|(?>.))*?)\n(\t*) /  ----------------------------------------------------------------------------------- */
		//e.g.	Using `_emphasis_` will generate ``emphasis``.
		'CODE'	=> '/(``|(`))((?(2)(?:``|[^`]+)+?|.+?))\1(?!`)/',
		//HTML comments could contain ReMarkable syntax. the TOC marker is stored here as the “&” must not be
		//encoded by ReMarkable (allowing for the TOC marker in CODE/PRE) and musn’t be wrapped in `
`
		'#'	=> '/|&__TOC__;/s'
		
	) as $tag => $regx) if (!$offset=0) while (
		preg_match ($regx, $source_text, $m, PREG_OFFSET_CAPTURE, (int) $offset)
	) {
		switch ($tag) {
			case 'PRE':
				//if language paramter given, wrap in a code span too
				$text = (strlen ($m[1][0]) ? '
' : '
').
					//HTML-encode the preformatted block (HTML code examples, &c.)
					htmlspecialchars (
						//if the PRE block was indented (inside a list), unindent accordingly
						preg_replace ('/^\t{'.strlen ($m[3][0]).'}/m', '', $m[2][0]),
						ENT_NOQUOTES, 'UTF-8'
					).
					(strlen ($m[1][0]) ? '
' : '
')
				;
				break;
			case 'CODE':
				$text = (strlen ($m[2][0]) ? '' : '').
					htmlspecialchars ($m[3][0], ENT_NOQUOTES, 'UTF-8').
					(strlen ($m[2][0]) ? '' : '')
				;
				break;
			default:
				$text = $m[0][0];
		}
		
		//capture the element
		array_push ($placeholders[$tag], $text);
		//replace with placeholder tag
		$source_text = substr_replace ($source_text,
			//make the placeholder tag the same size of the content being replaced, for word wrapping to work
			"¡$tag".str_repeat ('%', max (0, strlen ($text) - (strlen ($tag) + 3)))."!",
			$m[0][1], strlen ($m[0][0])
		);
		//continue searching from after this placeholder
		$offset = $m[0][1] + strlen ($m[0][0]);
	}
	
	/* 2. hyperlinks
	   =============================================================================================================== */
	/* ReMarkable hyperlinks have to be processed before removing the remaining HTML tags because:
	   a. they look like HTML tags, and
	   b. accidental inline markup could break the URL. for example, two underscores in a URL would add ``s
	*/
	
	//list of mime-types for hyperlinks pointing directly to a file:
	//--------------------------------------------------------------
	//note: this is absolutely not supposed to be a comprehensive list; quite the opposite in fact. this list is just
	//my idea of the most important files that are directly hyperlinked to in articles--that user’s may want to be
	//warned about beforehand via CSS mime-type icons &c.
	$link_mimes = array (
		//images
		'jpg'     => 'image/jpeg',			'jpeg' => 'image/jpeg',
		'png'     => 'image/png',			'gif'  => 'image/gif',
		'psd'     => 'image/vnd.adobe.photoshop',
		'ai'      => 'application/postscript',		'eps'  => 'application/postscript',
		'svg'     => 'image/svg+xml',			'svgz' => 'image/svg+xml',
		//documents
		'txt'     => 'text/plain',			'pdf'  => 'application/pdf',
		'doc'     => 'application/msword',		'odt'  => 'application/vnd.oasis.opendocument.text',
		'xls'     => 'application/vnd.ms-excel',	'ods'  => 'application/vnd.oasis.opendocument.spreadsheet',
		'ppt'     => 'application/vnd.ms-powerpoint',	'odp'  => 'application/vnd.oasis.opendocument.presentation',
		'csv'     => 'text/csv',
		//code
		'css'     => 'text/css',
		'js'      => 'application/javascript',
		//downloads
		'exe'     => 'application/octet-stream',
		'dmg'     => 'application/octet-stream',	'iso'  => 'application/octet-stream',
		'rar'     => 'application/x-rar-compressed',	'zip'  => 'application/zip',
		'tar'     => 'application/x-tar',		'gz'   => 'application/x-gzip',
		'torrent' => 'application/x-bittorrent',
		//audio
		'oga'     => 'audo/ogg',			'wav'  => 'audio/wav',
		'mp3'     => 'audio/mpeg',			'm4a'  => 'audio/mp4a-latm',
		'midi'    => 'audio/midi',
		//video
		'mp4'     => 'video/mp4',			'm4v'  => 'video/mp4',
		'mpeg'    => 'video/mpeg',			'mpg'  => 'video/mpeg',
		'mov'     => 'video/quicktime',			'avi'  => 'video/x-msvideo',
		'ogv'     => 'video/ogg'
	);
	//regular expression to identify the various forms of a ReMarkable hyperlink:
	$regx =
	//e.g.	Click 	(with description)
	//	Click .		(relative, with description)
	//	Visit 			(without description. protocol is optional in this style)
	'/<(?:([^<>]+?)[ ]\()?						# $1 = optional description
	(\^)?								# $2 = optional no-follow marker
	(								# $3 = whole URL
		((?:[a-z]{3,10}:)?\/{0,3})?				# $4 = protocol
		(?:www\.)?						# ignore www
		(							# $5 = friendly URL (no protocol)
			([a-z0-9._%+-]+@[a-z0-9.-]+)?			# $6 = email address
			(?(4)[a-z0-9\.-]{2,}(?:\.[a-z]{2,4})+   |	# domain name (mandatory if protocol given)
			 (?(1)|[a-z0-9\.-]{2,}(?:\.[a-z]{2,4})+))	# domain name (mandatory if no description)
			(						# $7 = folders and filename, relative URL
				(?(4)\/|(?(1)|\/))			# slash required after full domain
				[\/a-z0-9_!~\*\'\(\)\.;\?:@&=\+\$,%-]*	# folders and filename
			)?			
			(?(7)(?:\#[a-z0-9_\.-]+)?)			# #bookmark
		)
	)
	(?(1)\))>/xi';							# closing ) if description present
	
	//step through each hyperlink found…
	while (preg_match ($regx, $source_text, $m)) $source_text = preg_replace ($regx,
		''.
			//link text: either the description, or the friendly URL
			(strlen ($m[1]) ? $m[1] : $m[5]).
		'',
		//replace only one link so that the loop steps through one link at a time (for `$m` in `preg_match`)
		$source_text, 1
	);
	
	
	/* 3. images
	   =============================================================================================================== */
	/* --- inline images --------------------------------------------------------------------------------------------- */
	//e.g.	<"alt text" /url/to/image.png>				with alt-text
	//	<"alt text" /url/to/image.png "optional title">		-or- with alt-text and title
	$regx = '/<("[^"]*")(?: |\n\s*)(\S+?\.(?:png|gif|jpe?g|svgz?))(?:(?: |\n\s*)("[^"]+"))?>/i';
	while (preg_match ($regx, $source_text, $m)) {
		//get the image size
		$info = getimagesize ($base_path.$m[2]);
		//construct the img tag
		$source_text = preg_replace ($regx,
			'',
		$source_text, 1);
	}
	
	
	/* 4. remove HTML tags
	   =============================================================================================================== */
	//the negative before and after avoids accidentally detecting inline quotes `<>`
	while (preg_match ('/(?|(?: [^>]+)?>(?!>))/', $source_text, $m, PREG_OFFSET_CAPTURE)) {
		//get the placeholder name
		$tag = strtoupper ($m[2][0]);
		//if this type of tag has not yet been recoreded, add a slot for it
		if (!isset ($placeholders[$tag])) $placeholders[$tag] = array ();
		//capture the tag
		array_push ($placeholders[$tag], $m[0][0]);
		//replace with placeholder tag
		$source_text = substr_replace ($source_text,
			//make the placeholder tag the same size of the content being replaced for word wrapping to work
			"¡$tag".str_repeat('%', max (0, strlen ($m[0][0]) - (strlen ($tag) + 3))).'!',
			$m[0][1], strlen ($m[0][0])
		);
	}
	
	//encode essential HTML entities not already encoded (`&`, `<`, `>`),
	//we do not double encode, so that entities that you’ve already written in the source text are kept
	$source_text = htmlspecialchars ($source_text, ENT_NOQUOTES, 'UTF-8', false);
	
	
	/* 5. auto-correction: replace some ASCII conventions with unicode / HTML
	   =============================================================================================================== */
	foreach (array (
		//prime: 5′ (ft)				//double prime: 15″ (in)
		'/(\d)\'/'			=> '$1′',	'/([\d½¼])"/u'			=> '$1″',
		//smart single quotes: ‘ ’			//smart double quotes: “ ”
		'/(\B)\'(.*?)\'(\B)/'		=> '$1‘$2’$3',	'/(\B)"(.*?)"(\B)/'		=> '$1“$2”$3',
		//apostrophes: “won’t can’t” and “’till the ’90s” &c.
		'/(\B(?:\w+)?)\'(\w+\b)/'	=> '$1’$2',
		//em-dash: “--”					//en-dash “-to-” (don’t allow inside H* id)
		'/(? '—',		'/-to-(?!\S+\)\n[=-])/'		=> '–',
		//copyright: “(C)”				//all rights reserved: “(R)”
		'/\(C\)/i'			=> '©',		'/\(R\)/'			=> '®',
		//trademark: “^tm”
		'/\^tm/i'			=> '™',
		//ordinals / superscript
		'/(\d)(st|nd|rd|th)/'		=> '$1$2',
		'/([\w])\^([\w]+)/u'		=> '$1$2',
		//multiplication (use `x` to avoid)
		'/([\d ])x([\d ])?\b/'		=> '$1×$2',
		//fractions
		'/ 1\/2/'			=> '½',		'/ 1\/4/'			=> '¼',
		//plus-minus: “+/-” -> "±"			//“:therefore:”
		'/\+\/-/'			=> '±',		'/:therefore:|:ergo:/'		=> '∴'
		
	) as $regx => $replace) $source_text = preg_replace ($regx, $replace, $source_text);
	
	
	/* 6. process main markup
	   =============================================================================================================== */
	//I hope you’re fluent in regex
	$source_text = preg_replace (array (
		/* --- 
 -------------------------------------------------------------------------------------------- */
		//e.g.	The quick brown fox _
		//	jumps over¬the lazy dog
		'/¬| _(?=$)/m',
		/* --- 
 -------------------------------------------------------------------------------------------- */
		//i.e.	* * *
		'/^\s*\* \* \*$/m',
		/* ---  /  ----------------------------------------------------------------------------------- */
		//e.g.	I’m _emphasising_ this point *strongly*.
		'/(?:^|\b)_(.+?)_(?:\b|$)/',				'/\*(?!\t)(.+?)\*(?!\*)/',
		/* ---  /  ------------------------------------------------------------------------------------- */
		//e.g.	---This statement is false --- [This statement is true].
		'/\[(.+?)\]/',						'/---(?!-+)(.+?)(? -------------------------------------------------------------------------------------------- */
		//e.g.	I’ve finished reading ~The Lion, the Witch and the Wardrobe~.
		'/~(.+?)~/',
		/* ---  ----------------------------------------------------------------------------------------------- */
		//e.g.	He said «turn left here», but she said <>.
		'/(?:(\xAB)|(?:<){2})(.*?)(?(1)\xBB|(?:>){2})/u',
		/* ---  -------------------------------------------------------------------------------------------- */
		//e.g.	My {CSS|style sheet} is tweaked almost daily.	(with title)
		//	The {FBI} are like the British {MI5}.		(without title)
		'/\{([^\|}]+)(?:\|([^}]+))?}/e',
		/* ---  ------------------------------------------------------------------------------------------- */
		//e.g.	((legalese goes here))				(inline, block version handled later on)
		'/\({2}(.*?)\){2}(?!\))/'
	), array (
		/*
*/	'
',		/*
*/	"\n
",
		/**/	'$1',		/**/	'$1',
		/**/	'$1',	/**/	'$1',
		/**/	'$1', 	/**/		'$2',
		/**/	'"".stripslashes("$1").""',
		/**/	'$1'
		
	), $source_text);
	
	
	/* 7. headings
	   =============================================================================================================== */
	//capture the headings in the source text
	while (preg_match (
		//e.g.	### title ### (#id)	(atx-style, `# h1 #`, `## h2 ##`…, id is optional)
		//or-	Title (#id)		(H2, id is optional)
		//	===========
		//	Title (#id)		(H3, id is optional)
		//	-----------
		'/^(#{1,6})?(?(1) )(.*?)(?(1) \1)(?: \(#([0-9a-z_-]+)\))?(?(1)|\n([=-]+))(?:\n|$)/mi',
		$source_text, $m1, PREG_OFFSET_CAPTURE
	)) {
		//detect heading level (number of #’s or ‘=’ bar for H2 / ‘-’ bar for H3)
		$h = strlen ($m1[1][0]) ? strlen ($m1[1][0]) : (substr ($m1[4][0], 0, 1) == "=" ? 2 : 3);
		$title = &$m1[2][0]; $hid = &$m1[3][0];
		
		/* title case the heading:
		   ------------------------------------------------------------------------------------------------------- */
		/* original Title Case script © John Gruber 
		   javascript port © David Gouch 
		*/
		//remove HTML, storing it for later
		//       placeholders    | tags     | entities
		$regx = '/\xA1[@#A-Z]+%*!|<\/?[^>]+>|&\S+;/u';
		preg_match_all ($regx, $title, $html, PREG_OFFSET_CAPTURE);
		$title = preg_replace ($regx, '', $title);
		
		//find each word (including punctuation attached)
		preg_match_all ('/[\w&`\'‘’"“\.@:\/\{\(\[<>_]+-? */u', $title, $m2, PREG_OFFSET_CAPTURE);
		foreach ($m2[0] as $m3) {
			//shorthand these- "match" and "index"
			list ($m, $i) = $m3;
			
			//correct offsets for multi-byte characters (`PREG_OFFSET_CAPTURE` returns *byte*-offset)
			//we fix this by recounting the text before the offset using multi-byte aware `strlen`
			$i = mb_strlen (substr ($title, 0, $i), 'UTF-8');
			
			//find words that should always be lowercase…
			//(never on the first word, and never if preceded by a colon)
			$m = $i>0 && mb_substr ($title, max (0, $i-2), 1, 'UTF-8') !== ':' && preg_match (
				'/^(a(nd?|s|t)?|b(ut|y)|en|for|i[fn]|o[fnr]|t(he|o)|vs?\.?|via)[ \-]/i', $m
			) ?	//…and convert them to lowercase
				mb_strtolower ($m, 'UTF-8')
				
			//else:	brackets and other wrappers
			: (	preg_match ('/[\'"_{(\[‘“]/u', mb_substr ($title, max (0, $i-1), 3, 'UTF-8'))
			?	//convert first letter within wrapper to uppercase
				mb_substr ($m, 0, 1, 'UTF-8').
				mb_strtoupper (mb_substr ($m, 1, 1, 'UTF-8'), 'UTF-8').
				mb_substr ($m, 2, mb_strlen ($m, 'UTF-8')-2, 'UTF-8')
				
			//else:	do not uppercase these cases
			: (	preg_match ('/[\])}]/', mb_substr ($title, max (0, $i-1), 3, 'UTF-8')) ||
				preg_match ('/[A-Z]+|&|\w+[._]\w+/u', mb_substr ($m, 1, mb_strlen ($m, 'UTF-8')-1, 'UTF-8'))
			?	$m
				//if all else fails, then no more fringe-cases; uppercase the word
			:	mb_strtoupper (mb_substr ($m, 0, 1, 'UTF-8'), 'UTF-8').
				mb_substr ($m, 1, mb_strlen ($m, 'UTF-8'), 'UTF-8')
			));
			
			//resplice the title with the change (`substr_replace` is not multi-byte aware)
			$title = mb_substr ($title, 0, $i, 'UTF-8').$m.
				 mb_substr ($title, $i+mb_strlen ($m, 'UTF-8'), mb_strlen ($title, 'UTF-8'), 'UTF-8')
			;
		}
		//restore the HTML
		foreach ($html[0] as &$tag) $title = substr_replace ($title, $tag[0], $tag[1], 0);
		/* ------------------------------------------------------------------------------------------------------- */
		
		//replace heading with HTML
		$source_text = substr_replace ($source_text,
			"$title\n\n",
			$m1[0][1], strlen ($m1[0][0])
		);
	}
	
	
	/* 8. blocks - lists / blockquotes
	   =============================================================================================================== */
	//see documentation (or read regex) for full list of supported bullet types. note that this has a capturing group
	$bullet = '(?:([\x{2022}*+-])|(?:[a-zA-Z]\.|#|(?:\d+\.){1,6}))';
	
	//capture, convert and unindent lists and blockquotes, recursively:
	do $source_text = preg_replace (array (
		/* --- «whitespace» -------------------------------------------------------------------------------------- */
		//remove white space on empty lines - simplifies regexes dealing with multiple lines
		'/^\s+\n/m',
		/* ---  ------------------------------------------------------------------------------------------- */
		//e.g.	((
		//		small used as a paragraph
		//	))
		'/^\({2}\n((?:.*\n)+?)\){2}/me',
		/* --- 
 -------------------------------------------------------------------------------------- */
		//e.g.	|	blockquote text
		'/^(?:\|(?:\t.*?)?\n)+\n/me',
		/* --- 
 / 
 --------------------------------------------------------------------------------------- */
		//i.e.	a number of li’s, see below
		"/^((?:$bullet(?:\\t+.*\\n{1,2})+)+)/emu",
		/* --- 
 ---------------------------------------------------------------------------------------------- */
		//e.g.	•	text
		"/(?:(?<=(?)(\n\n)))?^$bullet((?:\\t+.*(\n))+|(?:\\t+.*(?:\n|(\n\n)))+)(?=$bullet|\n<\/[uo]l>)/emu",
		/* --- 
 ---------------------------------------------------------------------------------------------- */
		'/^(:: .*\n{1,2}(?:(?:\t+.*\n{1,2})+)?)+/me',
		/* -- 
 / 
 ---------------------------------------------------------------------------------------- */
		//e.g.	:: definition term
		//		description…
		'/^:: (.*)\n?((?:\t+.*\n)+|(?:\t+.*(?:\n|(\n)\n)?)+)?\n(?=\n::|<\/dl>)/me'
	), array (
		/*«whitespace»*/"\n",
		/**/	'"\n".preg_replace("/^\\t/m","",trim(stripslashes("$1")))."\n\n"',
		/*
*/'"\n
\n\n".preg_replace("/^\|\\t?/m","",stripslashes("$0"))."
\n\n"',
		/*
/
*/	'"\n<".("$2"?"u":"o")."l>\n\n".trim(stripslashes("$1"))."\n\n\n\n"',
		/*
*/	'"
$1$4$5".preg_replace("/^\\t/m","",trim(stripslashes("$3")))."$1$4$5
\n\n"',
		/*
*/	'"
\n\n".trim(stripslashes("$0"))."\n
\n\n"',
		/*
/
*/	'"
".stripslashes("$1")."
\n\n".'.'("$2"?"
\n".stripslashes("$3").'.
				'(preg_replace("/^\\t/m","",stripslashes("$2"))).stripslashes("$3")."\n
\n\n":"")'
		
	), $source_text, -1, $continue);
	//because a list can contain another list / blockquote, once one is converted we loop again to catch the next level
	while ($continue);
	
	/* 9. indent and word-wrap
	   =============================================================================================================== */
	//start indenting at the base level for the whole document
	$depth = $indent;
	
	//the regex section above places blank lines either side of paragraphs in lists and either side of any tag that
	//begins / ends an indent. this section steps through these blank lines assessing the content inbetween:
	foreach (preg_split ('/\n{2,}/', $source_text, -1, PREG_SPLIT_NO_EMPTY) as $chunk) {
		//indent according to the current level
		if ($depth) $chunk = preg_replace ('/^/m', str_repeat ("\t", $depth), $chunk);
		
		//check each condition…
		foreach (array (
			//PRE blocks (will always have no indent regardless if they are inside an indented block)
			'pre'	=> '/^\s*(\xA1PRE%*!)/u',
			//list item without paragraphs
			'li'	=> '/^(\s*)
\n\1(?P
.*)\n\1<\/li>/s',
			//`
` without any paragraphs
			'dd'	=> '/^(\s*)
\n(?P
(?:\t+.*\n?)+)\1<\/dd>/m',
			//`` block paragraph
			'small'	=> '/^(\s*)\n(?P
(?:.*\n)+)\1<\/small>/m',
			//opening indent
			'open'	=> '/(.*?)^(\s*)<([uo]l|li|d[ld]|blockquote)>$(?P
.*)/ms',
			//closing indent
			'close'	=> '/(.*?)^(\s*?)\t<(\/)([uo]l|li|d[ld]|blockquote)>$(?P
.*)/ms',
			//block level elements that should not be wrapped in P tags
			'p'	=> '/^\s*(?:<\/?|(\xA1))(?:
				# tags alone on the line that should not be wrapped
				(img|small)
			|	# elements that start a line that should not be wrapped
				(?:article|aside|audio|blockquote|canvas|caption|col|colgroup|dialog|div|d[ltd]|embed
				  |fieldset|figure|footer|form|h[1-6r]|header|input|label|legend|li|nav|noscript|object|[ou]l
				  |optgroup|option|p|param|pre|script|section|select|source|table|t(?:body|foot|head)|t[dhr]
				  |textarea|video
				# don’t wrap HTML comments or TOC markers
				  |\#
				)
			)(?(1)%*!|[^>]*>)(?(2)(?:$|\n))/xui'
			
		) as $tag => $regx) if (
			//once a match is found, capture the regex results in `$m` and stop searching
			preg_match ($regx, $chunk, $m)
		) break;
		
		//note: ReMarkable does not wrap paragraphs around block elements. the “p” condition therefore works in
		//reverse and we know that an actual paragraph is matched when the regex doesn’t match and drops out of the
		//list of conditions -- leaving `$m` as empty
		
		//the “li”, “dd”, “small” and not “p” conditions contain a paragraph of text that has to be word-wrapped.
		//this text is stored in the regex named capture group “p” -> `$m['p']`. if no match is made `(!$m)` then
		//the whole chunk is a paragraph to be wrapped
		$p = rtrim (!$m ? $chunk : @$m['p']);
		
		//as explained above, word-wrap these conditions:
		if (($tag == 'li' || $tag == 'dd' || $tag == 'small' || !$m) && $margin>0) {
			//collapse whitespace in paragraphs. this removes HTML newlines (except before or after a `
`)
			//so that the paragraph can be wrapped cleanly by ReMarkable
			$p = rtrim (preg_replace ('/(?)\n\t*+(?!
)/', ' ', $p));
			
			//word-wrap:
			//calculate the current loss of margin due to the indent level
			$width = $margin - (8 * ($depth+1));
			//keep finding oversized lines until none are left…
			do $p = preg_replace (
				//find i. any line that’s longer than the margin cut-off point
				//    ii. the last space before the margin, as long as it’s not within an HTML tag -or-
				//   iii. the first space after the margin (for lines with very long URLs for example)
				'/^(?=.{'.($width+4).',})(.{1,'.$width.'}|.{'.$width.',}?) (?![^<]*?>)/m',
				//and chop
				"$1\n".str_repeat ("\t", $depth), $p, -1, $continue
			);
			while ($continue);
		}
		//reconstruct the chunk
		switch ($tag) {
			case 'pre'   : $chunk = $m[1];								       break;
			case 'li'    : $chunk = $m[1]."
$p
";						       break;
			case 'dd'    : $chunk = $m[1]."
\n".preg_replace ('/^/m', "\t", $p."\n").$m[1]."
";     break;
			case 'small' : $chunk = $m[1]."\n".preg_replace ('/^/m',"\t",$p."\n").$m[1].""; break;
			case 'open'  : $chunk = $m[1].$m[2]."<${m[3]}>".preg_replace ('/\n/', "\n\t", $p);   $depth++; break;
			case 'close' : $chunk = $m[1].$m[2]."<${m[3]}${m[4]}>".$p;			     $depth--; break;
			default:
				//wrap paragraph
				if (!$m) $chunk = str_repeat ("\t", $depth)."
\n".
						  preg_replace ('/^/m', "\t", $p)."\n".
						  str_repeat ("\t", $depth)."
"
				;
		}
		$source_text = @$result .= "\n$chunk";
	};
	
	/* 10. finalise
	   =============================================================================================================== */
	//tidy up the HTML
	foreach (array (
		//pair `
` tags together
		'/<\/p>\n\t*
/'					=> '
',
		//flatten a single line paragraph in a `
` -> `
...
`
		'/
\n(\t*)\t
\n\t+(.*)\n\t+<\/p>\n\t+<\/li>/'	=> "
\n$1\t
$2
\n$1
",
		//pair `
` tags together (except single-line ones)
		'/\n(\t*)<\/li>\n\t*
\n/'				=> "\n$1
\n",
		//add double blank lines above H2,3 (easy to see headings when scrolling)
		'/^(\t*)(]*>.*)$/m'				=> "$1\n$1\n$1$2",
		//but not when one immediately proceeds another
		'/(<\/h[23]>)(?:\n(\t*)){3}(]*>)/'		=> "$1\n$2$3",
		//blank line either side of `
`
		'/^(\t*)
/ms'					=> "$1\n$0\n$1",
		//blank line either side of PRE blocks (have no indent themselves, so it has to be borrowed)
		'/^\xA1PRE%*!\n(\t*)/mu'				=> "$1\n$1$0\n$1",
		//remove tripple blank lines caused by combinations of the above
		'/^(?:(\t*)\n){3}/m'					=> "$1\n$1\n"
		
	) as $regx => $replace) $source_text = preg_replace ($regx, $replace, $source_text);
	
	/* restore placeholders
	   --------------------------------------------------------------------------------------------------------------- */
	//restore in reverse order so that pre and code spans that contain placeholders [documentation] don’t conflict
	$placeholders = array_reverse ($placeholders, true);
	//restore each saved chunk of HTML, for each type of tag
	foreach ($placeholders as $tag => &$tags) foreach ($tags as &$html) if (
		preg_match ("/\\xA1$tag%*!/u", $source_text, $m, PREG_OFFSET_CAPTURE)
	) $source_text = substr_replace ($source_text, $html, $m[0][1], strlen ($m[0][0]));
	
	/* auto table of contents
	   --------------------------------------------------------------------------------------------------------------- */
	//creates a table of contents from headings with IDs. this has to be done last because `` spans in headings
	//would be duplicated in the TOC and the HTML would not be restored correctly above. the offset is captured so that
	//only headings *after* the TOC marker are included in the table of contents
	if (preg_match ('/^(\t*)&__TOC__;/m', $source_text, $i, PREG_OFFSET_CAPTURE)) {
		preg_match_all ('/(.*?)<\/h\1>/i', $source_text, $h, PREG_SET_ORDER, $i[0][1]);
		//the simplest way to create a nested list is to let ReMarkable do it!
		foreach ($h as &$m) $toc .= str_repeat ("\t", (int) $m[1]-2)."#\t${m[3]}\n";
		$source_text = str_replace ('&__TOC__;', reMarkable ($toc, strlen ($i[1][0]), $margin), $source_text);
	}
	
	//a trailing line break is never given so that ReMarkable can be used for short inline strings in your HTML
	return trim ($source_text, "\n");
}
/* ==================================================================================================== code is art === */ ?>