Parsedown.php

<?php

/*
The MIT License (MIT)

Copyright (c) 2013-2018 Emanuil Rusev, erusev.com

Permission is hereby granted, free of charge, to any person obtaining a copy of
this software and associated documentation files (the "Software"), to deal in
the Software without restriction, including without limitation the rights to
use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
the Software, and to permit persons to whom the Software is furnished to do so,
subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/

#
#
# Parsedown
# http://parsedown.org
#
# (c) Emanuil Rusev
# http://erusev.com
#
# For the full license information, view the LICENSE file that was distributed
# with this source code.
#
#

class Parsedown
{
	# ~

	const version = '1.8.0-beta-7';

	# ~

	function text($text)
	{
		$Elements = $this->textElements($text);

		# convert to markup
		$markup = $this->elements($Elements);

		# trim line breaks
		$markup = trim($markup, "\n");

		return $markup;
	}

	protected function textElements($text)
	{
		# make sure no definitions are set
		$this->DefinitionData = array();

		# standardize line breaks
		$text = str_replace(array("\r\n", "\r"), "\n", $text);

		# remove surrounding line breaks
		$text = trim($text, "\n");

		# split text into lines
		$lines = explode("\n", $text);

		# iterate through lines to identify blocks
		return $this->linesElements($lines);
	}

	#
	# Setters
	#

	function setBreaksEnabled($breaksEnabled)
	{
		$this->breaksEnabled = $breaksEnabled;

		return $this;
	}

	protected $breaksEnabled;

	function setMarkupEscaped($markupEscaped)
	{
		$this->markupEscaped = $markupEscaped;

		return $this;
	}

	protected $markupEscaped;

	function setUrlsLinked($urlsLinked)
	{
		$this->urlsLinked = $urlsLinked;

		return $this;
	}

	protected $urlsLinked = true;

	function setSafeMode($safeMode)
	{
		$this->safeMode = (bool) $safeMode;

		return $this;
	}

	protected $safeMode;

	function setStrictMode($strictMode)
	{
		$this->strictMode = (bool) $strictMode;

		return $this;
	}

	protected $strictMode;

	protected $safeLinksWhitelist = array(
		'http://',
		'https://',
		'ftp://',
		'ftps://',
		'mailto:',
		'tel:',
		'data:image/png;base64,',
		'data:image/gif;base64,',
		'data:image/jpeg;base64,',
		'irc:',
		'ircs:',
		'git:',
		'ssh:',
		'news:',
		'steam:',
	);

	#
	# Lines
	#

	protected $BlockTypes = array(
		'#' => array('Header'),
		'*' => array('Rule', 'List'),
		'+' => array('List'),
		'-' => array('SetextHeader', 'Table', 'Rule', 'List'),
		'0' => array('List'),
		'1' => array('List'),
		'2' => array('List'),
		'3' => array('List'),
		'4' => array('List'),
		'5' => array('List'),
		'6' => array('List'),
		'7' => array('List'),
		'8' => array('List'),
		'9' => array('List'),
		':' => array('Table'),
		'<' => array('Comment', 'Markup'),
		'=' => array('SetextHeader'),
		'>' => array('Quote'),
		'[' => array('Reference'),
		'_' => array('Rule'),
		'`' => array('FencedCode'),
		'|' => array('Table'),
		'~' => array('FencedCode'),
	);

	# ~

	protected $unmarkedBlockTypes = array(
		'Code',
	);

	#
	# Blocks
	#

	protected function lines(array $lines)
	{
		return $this->elements($this->linesElements($lines));
	}

	protected function linesElements(array $lines)
	{
		$Elements = array();
		$CurrentBlock = null;

		foreach ($lines as $line)
		{
			if (chop($line) === '')
			{
				if (isset($CurrentBlock))
				{
					$CurrentBlock['interrupted'] = (isset($CurrentBlock['interrupted'])
						? $CurrentBlock['interrupted'] + 1 : 1
					);
				}

				continue;
			}

			while (($beforeTab = strstr($line, "\t", true)) !== false)
			{
				$shortage = 4 - mb_strlen($beforeTab, 'utf-8') % 4;

				$line = $beforeTab
					. str_repeat(' ', $shortage)
					. substr($line, strlen($beforeTab) + 1)
				;
			}

			$indent = strspn($line, ' ');

			$text = $indent > 0 ? substr($line, $indent) : $line;

			# ~

			$Line = array('body' => $line, 'indent' => $indent, 'text' => $text);

			# ~

			if (isset($CurrentBlock['continuable']))
			{
				$methodName = 'block' . $CurrentBlock['type'] . 'Continue';
				$Block = $this->$methodName($Line, $CurrentBlock);

				if (isset($Block))
				{
					$CurrentBlock = $Block;

					continue;
				}
				else
				{
					if ($this->isBlockCompletable($CurrentBlock['type']))
					{
						$methodName = 'block' . $CurrentBlock['type'] . 'Complete';
						$CurrentBlock = $this->$methodName($CurrentBlock);
					}
				}
			}

			# ~

			$marker = $text[0];

			# ~

			$blockTypes = $this->unmarkedBlockTypes;

			if (isset($this->BlockTypes[$marker]))
			{
				foreach ($this->BlockTypes[$marker] as $blockType)
				{
					$blockTypes []= $blockType;
				}
			}

			#
			# ~

			foreach ($blockTypes as $blockType)
			{
				$Block = $this->{"block$blockType"}($Line, $CurrentBlock);

				if (isset($Block))
				{
					$Block['type'] = $blockType;

					if ( ! isset($Block['identified']))
					{
						if (isset($CurrentBlock))
						{
							$Elements[] = $this->extractElement($CurrentBlock);
						}

						$Block['identified'] = true;
					}

					if ($this->isBlockContinuable($blockType))
					{
						$Block['continuable'] = true;
					}

					$CurrentBlock = $Block;

					continue 2;
				}
			}

			# ~

			if (isset($CurrentBlock) and $CurrentBlock['type'] === 'Paragraph')
			{
				$Block = $this->paragraphContinue($Line, $CurrentBlock);
			}

			if (isset($Block))
			{
				$CurrentBlock = $Block;
			}
			else
			{
				if (isset($CurrentBlock))
				{
					$Elements[] = $this->extractElement($CurrentBlock);
				}

				$CurrentBlock = $this->paragraph($Line);

				$CurrentBlock['identified'] = true;
			}
		}

		# ~

		if (isset($CurrentBlock['continuable']) and $this->isBlockCompletable($CurrentBlock['type']))
		{
			$methodName = 'block' . $CurrentBlock['type'] . 'Complete';
			$CurrentBlock = $this->$methodName($CurrentBlock);
		}

		# ~

		if (isset($CurrentBlock))
		{
			$Elements[] = $this->extractElement($CurrentBlock);
		}

		# ~

		return $Elements;
	}

	protected function extractElement(array $Component)
	{
		if ( ! isset($Component['element']))
		{
			if (isset($Component['markup']))
			{
				$Component['element'] = array('rawHtml' => $Component['markup']);
			}
			elseif (isset($Component['hidden']))
			{
				$Component['element'] = array();
			}
		}

		return $Component['element'];
	}

	protected function isBlockContinuable($Type)
	{
		return method_exists($this, 'block' . $Type . 'Continue');
	}

	protected function isBlockCompletable($Type)
	{
		return method_exists($this, 'block' . $Type . 'Complete');
	}

	#
	# Code

	protected function blockCode($Line, $Block = null)
	{
		if (isset($Block) and $Block['type'] === 'Paragraph' and ! isset($Block['interrupted']))
		{
			return;
		}

		if ($Line['indent'] >= 4)
		{
			$text = substr($Line['body'], 4);

			$Block = array(
				'element' => array(
					'name' => 'pre',
					'element' => array(
						'name' => 'code',
						'text' => $text,
					),
				),
			);

			return $Block;
		}
	}

	protected function blockCodeContinue($Line, $Block)
	{
		if ($Line['indent'] >= 4)
		{
			if (isset($Block['interrupted']))
			{
				$Block['element']['element']['text'] .= str_repeat("\n", $Block['interrupted']);

				unset($Block['interrupted']);
			}

			$Block['element']['element']['text'] .= "\n";

			$text = substr($Line['body'], 4);

			$Block['element']['element']['text'] .= $text;

			return $Block;
		}
	}

	protected function blockCodeComplete($Block)
	{
		return $Block;
	}

	#
	# Comment

	protected function blockComment($Line)
	{
		if ($this->markupEscaped or $this->safeMode)
		{
			return;
		}

		if (strpos($Line['text'], '<!--') === 0)
		{
			$Block = array(
				'element' => array(
					'rawHtml' => $Line['body'],
					'autobreak' => true,
				),
			);

			if (strpos($Line['text'], '-->') !== false)
			{
				$Block['closed'] = true;
			}

			return $Block;
		}
	}

	protected function blockCommentContinue($Line, array $Block)
	{
		if (isset($Block['closed']))
		{
			return;
		}

		$Block['element']['rawHtml'] .= "\n" . $Line['body'];

		if (strpos($Line['text'], '-->') !== false)
		{
			$Block['closed'] = true;
		}

		return $Block;
	}

	#
	# Fenced Code

	protected function blockFencedCode($Line)
	{
		$marker = $Line['text'][0];

		$openerLength = strspn($Line['text'], $marker);

		if ($openerLength < 3)
		{
			return;
		}

		$infostring = trim(substr($Line['text'], $openerLength), "\t ");

		if (strpos($infostring, '`') !== false)
		{
			return;
		}

		$Element = array(
			'name' => 'code',
			'text' => '',
		);

		if ($infostring !== '')
		{
			/**
			 * https://www.w3.org/TR/2011/WD-html5-20110525/elements.html#classes
			 * Every HTML element may have a class attribute specified.
			 * The attribute, if specified, must have a value that is a set
			 * of space-separated tokens representing the various classes
			 * that the element belongs to.
			 * [...]
			 * The space characters, for the purposes of this specification,
			 * are U+0020 SPACE, U+0009 CHARACTER TABULATION (tab),
			 * U+000A LINE FEED (LF), U+000C FORM FEED (FF), and
			 * U+000D CARRIAGE RETURN (CR).
			 */
			$language = substr($infostring, 0, strcspn($infostring, " \t\n\f\r"));

			$Element['attributes'] = array('class' => "language-$language");
		}

		$Block = array(
			'char' => $marker,
			'openerLength' => $openerLength,
			'element' => array(
				'name' => 'pre',
				'element' => $Element,
			),
		);

		return $Block;
	}

	protected function blockFencedCodeContinue($Line, $Block)
	{
		if (isset($Block['complete']))
		{
			return;
		}

		if (isset($Block['interrupted']))
		{
			$Block['element']['element']['text'] .= str_repeat("\n", $Block['interrupted']);

			unset($Block['interrupted']);
		}

		if (($len = strspn($Line['text'], $Block['char'])) >= $Block['openerLength']
			and chop(substr($Line['text'], $len), ' ') === ''
		) {
			$Block['element']['element']['text'] = substr($Block['element']['element']['text'], 1);

			$Block['complete'] = true;

			return $Block;
		}

		$Block['element']['element']['text'] .= "\n" . $Line['body'];

		return $Block;
	}

	protected function blockFencedCodeComplete($Block)
	{
		return $Block;
	}

	#
	# Header

	protected function blockHeader($Line)
	{
		$level = strspn($Line['text'], '#');

		if ($level > 6)
		{
			return;
		}

		$text = trim($Line['text'], '#');

		if ($this->strictMode and isset($text[0]) and $text[0] !== ' ')
		{
			return;
		}

		$text = trim($text, ' ');

		$Block = array(
			'element' => array(
				'name' => 'h' . $level,
				'handler' => array(
					'function' => 'lineElements',
					'argument' => $text,
					'destination' => 'elements',
				)
			),
		);

		return $Block;
	}

	#
	# List

	protected function blockList($Line, array $CurrentBlock = null)
	{
		list($name, $pattern) = $Line['text'][0] <= '-' ? array('ul', '[*+-]') : array('ol', '[0-9]{1,9}+[.\)]');

		if (preg_match('/^('.$pattern.'([ ]++|$))(.*+)/', $Line['text'], $matches))
		{
			$contentIndent = strlen($matches[2]);

			if ($contentIndent >= 5)
			{
				$contentIndent -= 1;
				$matches[1] = substr($matches[1], 0, -$contentIndent);
				$matches[3] = str_repeat(' ', $contentIndent) . $matches[3];
			}
			elseif ($contentIndent === 0)
			{
				$matches[1] .= ' ';
			}

			$markerWithoutWhitespace = strstr($matches[1], ' ', true);

			$Block = array(
				'indent' => $Line['indent'],
				'pattern' => $pattern,
				'data' => array(
					'type' => $name,
					'marker' => $matches[1],
					'markerType' => ($name === 'ul' ? $markerWithoutWhitespace : substr($markerWithoutWhitespace, -1)),
				),
				'element' => array(
					'name' => $name,
					'elements' => array(),
				),
			);
			$Block['data']['markerTypeRegex'] = preg_quote($Block['data']['markerType'], '/');

			if ($name === 'ol')
			{
				$listStart = ltrim(strstr($matches[1], $Block['data']['markerType'], true), '0') ?: '0';

				if ($listStart !== '1')
				{
					if (
						isset($CurrentBlock)
						and $CurrentBlock['type'] === 'Paragraph'
						and ! isset($CurrentBlock['interrupted'])
					) {
						return;
					}

					$Block['element']['attributes'] = array('start' => $listStart);
				}
			}

			$Block['li'] = array(
				'name' => 'li',
				'handler' => array(
					'function' => 'li',
					'argument' => !empty($matches[3]) ? array($matches[3]) : array(),
					'destination' => 'elements'
				)
			);

			$Block['element']['elements'] []= & $Block['li'];

			return $Block;
		}
	}

	protected function blockListContinue($Line, array $Block)
	{
		if (isset($Block['interrupted']) and empty($Block['li']['handler']['argument']))
		{
			return null;
		}

		$requiredIndent = ($Block['indent'] + strlen($Block['data']['marker']));

		if ($Line['indent'] < $requiredIndent
			and (
				(
					$Block['data']['type'] === 'ol'
					and preg_match('/^[0-9]++'.$Block['data']['markerTypeRegex'].'(?:[ ]++(.*)|$)/', $Line['text'], $matches)
				) or (
					$Block['data']['type'] === 'ul'
					and preg_match('/^'.$Block['data']['markerTypeRegex'].'(?:[ ]++(.*)|$)/', $Line['text'], $matches)
				)
			)
		) {
			if (isset($Block['interrupted']))
			{
				$Block['li']['handler']['argument'] []= '';

				$Block['loose'] = true;

				unset($Block['interrupted']);
			}

			unset($Block['li']);

			$text = isset($matches[1]) ? $matches[1] : '';

			$Block['indent'] = $Line['indent'];

			$Block['li'] = array(
				'name' => 'li',
				'handler' => array(
					'function' => 'li',
					'argument' => array($text),
					'destination' => 'elements'
				)
			);

			$Block['element']['elements'] []= & $Block['li'];

			return $Block;
		}
		elseif ($Line['indent'] < $requiredIndent and $this->blockList($Line))
		{
			return null;
		}

		if ($Line['text'][0] === '[' and $this->blockReference($Line))
		{
			return $Block;
		}

		if ($Line['indent'] >= $requiredIndent)
		{
			if (isset($Block['interrupted']))
			{
				$Block['li']['handler']['argument'] []= '';

				$Block['loose'] = true;

				unset($Block['interrupted']);
			}

			$text = substr($Line['body'], $requiredIndent);

			$Block['li']['handler']['argument'] []= $text;

			return $Block;
		}

		if ( ! isset($Block['interrupted']))
		{
			$text = preg_replace('/^[ ]{0,'.$requiredIndent.'}+/', '', $Line['body']);

			$Block['li']['handler']['argument'] []= $text;

			return $Block;
		}
	}

	protected function blockListComplete(array $Block)
	{
		if (isset($Block['loose']))
		{
			foreach ($Block['element']['elements'] as &$li)
			{
				if (end($li['handler']['argument']) !== '')
				{
					$li['handler']['argument'] []= '';
				}
			}
		}

		return $Block;
	}

	#
	# Quote

	protected function blockQuote($Line)
	{
		if (preg_match('/^>[ ]?+(.*+)/', $Line['text'], $matches))
		{
			$Block = array(
				'element' => array(
					'name' => 'blockquote',
					'handler' => array(
						'function' => 'linesElements',
						'argument' => (array) $matches[1],
						'destination' => 'elements',
					)
				),
			);

			return $Block;
		}
	}

	protected function blockQuoteContinue($Line, array $Block)
	{
		if (isset($Block['interrupted']))
		{
			return;
		}

		if ($Line['text'][0] === '>' and preg_match('/^>[ ]?+(.*+)/', $Line['text'], $matches))
		{
			$Block['element']['handler']['argument'] []= $matches[1];

			return $Block;
		}

		if ( ! isset($Block['interrupted']))
		{
			$Block['element']['handler']['argument'] []= $Line['text'];

			return $Block;
		}
	}

	#
	# Rule

	protected function blockRule($Line)
	{
		$marker = $Line['text'][0];

		if (substr_count($Line['text'], $marker) >= 3 and chop($Line['text'], " $marker") === '')
		{
			$Block = array(
				'element' => array(
					'name' => 'hr',
				),
			);

			return $Block;
		}
	}

	#
	# Setext

	protected function blockSetextHeader($Line, array $Block = null)
	{
		if ( ! isset($Block) or $Block['type'] !== 'Paragraph' or isset($Block['interrupted']))
		{
			return;
		}

		if ($Line['indent'] < 4 and chop(chop($Line['text'], ' '), $Line['text'][0]) === '')
		{
			$Block['element']['name'] = $Line['text'][0] === '=' ? 'h1' : 'h2';

			return $Block;
		}
	}

	#
	# Markup

	protected function blockMarkup($Line)
	{
		if ($this->markupEscaped or $this->safeMode)
		{
			return;
		}

		if (preg_match('/^<[\/]?+(\w*)(?:[ ]*+'.$this->regexHtmlAttribute.')*+[ ]*+(\/)?>/', $Line['text'], $matches))
		{
			$element = strtolower($matches[1]);

			if (in_array($element, $this->textLevelElements))
			{
				return;
			}

			$Block = array(
				'name' => $matches[1],
				'element' => array(
					'rawHtml' => $Line['text'],
					'autobreak' => true,
				),
			);

			return $Block;
		}
	}

	protected function blockMarkupContinue($Line, array $Block)
	{
		if (isset($Block['closed']) or isset($Block['interrupted']))
		{
			return;
		}

		$Block['element']['rawHtml'] .= "\n" . $Line['body'];

		return $Block;
	}

	#
	# Reference

	protected function blockReference($Line)
	{
		if (strpos($Line['text'], ']') !== false
			and preg_match('/^\[(.+?)\]:[ ]*+<?(\S+?)>?(?:[ ]+["\'(](.+)["\')])?[ ]*+$/', $Line['text'], $matches)
		) {
			$id = strtolower($matches[1]);

			$Data = array(
				'url' => $matches[2],
				'title' => isset($matches[3]) ? $matches[3] : null,
			);

			$this->DefinitionData['Reference'][$id] = $Data;

			$Block = array(
				'element' => array(),
			);

			return $Block;
		}
	}

	#
	# Table

	protected function blockTable($Line, array $Block = null)
	{
		if ( ! isset($Block) or $Block['type'] !== 'Paragraph' or isset($Block['interrupted']))
		{
			return;
		}

		if (
			strpos($Block['element']['handler']['argument'], '|') === false
			and strpos($Line['text'], '|') === false
			and strpos($Line['text'], ':') === false
			or strpos($Block['element']['handler']['argument'], "\n") !== false
		) {
			return;
		}

		if (chop($Line['text'], ' -:|') !== '')
		{
			return;
		}

		$alignments = array();

		$divider = $Line['text'];

		$divider = trim($divider);
		$divider = trim($divider, '|');

		$dividerCells = explode('|', $divider);

		foreach ($dividerCells as $dividerCell)
		{
			$dividerCell = trim($dividerCell);

			if ($dividerCell === '')
			{
				return;
			}

			$alignment = null;

			if ($dividerCell[0] === ':')
			{
				$alignment = 'left';
			}

			if (substr($dividerCell, - 1) === ':')
			{
				$alignment = $alignment === 'left' ? 'center' : 'right';
			}

			$alignments []= $alignment;
		}

		# ~

		$HeaderElements = array();

		$header = $Block['element']['handler']['argument'];

		$header = trim($header);
		$header = trim($header, '|');

		$headerCells = explode('|', $header);

		if (count($headerCells) !== count($alignments))
		{
			return;
		}

		foreach ($headerCells as $index => $headerCell)
		{
			$headerCell = trim($headerCell);

			$HeaderElement = array(
				'name' => 'th',
				'handler' => array(
					'function' => 'lineElements',
					'argument' => $headerCell,
					'destination' => 'elements',
				)
			);

			if (isset($alignments[$index]))
			{
				$alignment = $alignments[$index];

				$HeaderElement['attributes'] = array(
					'style' => "text-align: $alignment;",
				);
			}

			$HeaderElements []= $HeaderElement;
		}

		# ~

		$Block = array(
			'alignments' => $alignments,
			'identified' => true,
			'element' => array(
				'name' => 'table',
				'elements' => array(),
			),
		);

		$Block['element']['elements'] []= array(
			'name' => 'thead',
		);

		$Block['element']['elements'] []= array(
			'name' => 'tbody',
			'elements' => array(),
		);

		$Block['element']['elements'][0]['elements'] []= array(
			'name' => 'tr',
			'elements' => $HeaderElements,
		);

		return $Block;
	}

	protected function blockTableContinue($Line, array $Block)
	{
		if (isset($Block['interrupted']))
		{
			return;
		}

		if (count($Block['alignments']) === 1 or $Line['text'][0] === '|' or strpos($Line['text'], '|'))
		{
			$Elements = array();

			$row = $Line['text'];

			$row = trim($row);
			$row = trim($row, '|');

			preg_match_all('/(?:(\\\\[|])|[^|`]|`[^`]++`|`)++/', $row, $matches);

			$cells = array_slice($matches[0], 0, count($Block['alignments']));

			foreach ($cells as $index => $cell)
			{
				$cell = trim($cell);

				$Element = array(
					'name' => 'td',
					'handler' => array(
						'function' => 'lineElements',
						'argument' => $cell,
						'destination' => 'elements',
					)
				);

				if (isset($Block['alignments'][$index]))
				{
					$Element['attributes'] = array(
						'style' => 'text-align: ' . $Block['alignments'][$index] . ';',
					);
				}

				$Elements []= $Element;
			}

			$Element = array(
				'name' => 'tr',
				'elements' => $Elements,
			);

			$Block['element']['elements'][1]['elements'] []= $Element;

			return $Block;
		}
	}

	#
	# ~
	#

	protected function paragraph($Line)
	{
		return array(
			'type' => 'Paragraph',
			'element' => array(
				'name' => 'p',
				'handler' => array(
					'function' => 'lineElements',
					'argument' => $Line['text'],
					'destination' => 'elements',
				),
			),
		);
	}

	protected function paragraphContinue($Line, array $Block)
	{
		if (isset($Block['interrupted']))
		{
			return;
		}

		$Block['element']['handler']['argument'] .= "\n".$Line['text'];

		return $Block;
	}

	#
	# Inline Elements
	#

	protected $InlineTypes = array(
		'!' => array('Image'),
		'&' => array('SpecialCharacter'),
		'*' => array('Emphasis'),
		':' => array('Url'),
		'<' => array('UrlTag', 'EmailTag', 'Markup'),
		'[' => array('Link'),
		'_' => array('Emphasis'),
		'`' => array('Code'),
		'~' => array('Strikethrough'),
		'\\' => array('EscapeSequence'),
	);

	# ~

	protected $inlineMarkerList = '!*_&[:<`~\\';

	#
	# ~
	#

	public function line($text, $nonNestables = array())
	{
		return $this->elements($this->lineElements($text, $nonNestables));
	}

	protected function lineElements($text, $nonNestables = array())
	{
		# standardize line breaks
		$text = str_replace(array("\r\n", "\r"), "\n", $text);

		$Elements = array();

		$nonNestables = (empty($nonNestables)
			? array()
			: array_combine($nonNestables, $nonNestables)
		);

		# $excerpt is based on the first occurrence of a marker

		while ($excerpt = strpbrk($text, $this->inlineMarkerList))
		{
			$marker = $excerpt[0];

			$markerPosition = strlen($text) - strlen($excerpt);

			$Excerpt = array('text' => $excerpt, 'context' => $text);

			foreach ($this->InlineTypes[$marker] as $inlineType)
			{
				# check to see if the current inline type is nestable in the current context

				if (isset($nonNestables[$inlineType]))
				{
					continue;
				}

				$Inline = $this->{"inline$inlineType"}($Excerpt);

				if ( ! isset($Inline))
				{
					continue;
				}

				# makes sure that the inline belongs to "our" marker

				if (isset($Inline['position']) and $Inline['position'] > $markerPosition)
				{
					continue;
				}

				# sets a default inline position

				if ( ! isset($Inline['position']))
				{
					$Inline['position'] = $markerPosition;
				}

				# cause the new element to 'inherit' our non nestables


				$Inline['element']['nonNestables'] = isset($Inline['element']['nonNestables'])
					? array_merge($Inline['element']['nonNestables'], $nonNestables)
					: $nonNestables
				;

				# the text that comes before the inline
				$unmarkedText = substr($text, 0, $Inline['position']);

				# compile the unmarked text
				$InlineText = $this->inlineText($unmarkedText);
				$Elements[] = $InlineText['element'];

				# compile the inline
				$Elements[] = $this->extractElement($Inline);

				# remove the examined text
				$text = substr($text, $Inline['position'] + $Inline['extent']);

				continue 2;
			}

			# the marker does not belong to an inline

			$unmarkedText = substr($text, 0, $markerPosition + 1);

			$InlineText = $this->inlineText($unmarkedText);
			$Elements[] = $InlineText['element'];

			$text = substr($text, $markerPosition + 1);
		}

		$InlineText = $this->inlineText($text);
		$Elements[] = $InlineText['element'];

		foreach ($Elements as &$Element)
		{
			if ( ! isset($Element['autobreak']))
			{
				$Element['autobreak'] = false;
			}
		}

		return $Elements;
	}

	#
	# ~
	#

	protected function inlineText($text)
	{
		$Inline = array(
			'extent' => strlen($text),
			'element' => array(),
		);

		$Inline['element']['elements'] = self::pregReplaceElements(
			$this->breaksEnabled ? '/[ ]*+\n/' : '/(?:[ ]*+\\\\|[ ]{2,}+)\n/',
			array(
				array('name' => 'br'),
				array('text' => "\n"),
			),
			$text
		);

		return $Inline;
	}

	protected function inlineCode($Excerpt)
	{
		$marker = $Excerpt['text'][0];

		if (preg_match('/^(['.$marker.']++)[ ]*+(.+?)[ ]*+(?<!['.$marker.'])\1(?!'.$marker.')/s', $Excerpt['text'], $matches))
		{
			$text = $matches[2];
			$text = preg_replace('/[ ]*+\n/', ' ', $text);

			return array(
				'extent' => strlen($matches[0]),
				'element' => array(
					'name' => 'code',
					'text' => $text,
				),
			);
		}
	}

	protected function inlineEmailTag($Excerpt)
	{
		$hostnameLabel = '[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?';

		$commonMarkEmail = '[a-zA-Z0-9.!#$%&\'*+\/=?^_`{|}~-]++@'
			. $hostnameLabel . '(?:\.' . $hostnameLabel . ')*';

		if (strpos($Excerpt['text'], '>') !== false
			and preg_match("/^<((mailto:)?$commonMarkEmail)>/i", $Excerpt['text'], $matches)
		){
			$url = $matches[1];

			if ( ! isset($matches[2]))
			{
				$url = "mailto:$url";
			}

			return array(
				'extent' => strlen($matches[0]),
				'element' => array(
					'name' => 'a',
					'text' => $matches[1],
					'attributes' => array(
						'href' => $url,
					),
				),
			);
		}
	}

	protected function inlineEmphasis($Excerpt)
	{
		if ( ! isset($Excerpt['text'][1]))
		{
			return;
		}

		$marker = $Excerpt['text'][0];

		if ($Excerpt['text'][1] === $marker and preg_match($this->StrongRegex[$marker], $Excerpt['text'], $matches))
		{
			$emphasis = 'strong';
		}
		elseif (preg_match($this->EmRegex[$marker], $Excerpt['text'], $matches))
		{
			$emphasis = 'em';
		}
		else
		{
			return;
		}

		return array(
			'extent' => strlen($matches[0]),
			'element' => array(
				'name' => $emphasis,
				'handler' => array(
					'function' => 'lineElements',
					'argument' => $matches[1],
					'destination' => 'elements',
				)
			),
		);
	}

	protected function inlineEscapeSequence($Excerpt)
	{
		if (isset($Excerpt['text'][1]) and in_array($Excerpt['text'][1], $this->specialCharacters))
		{
			return array(
				'element' => array('rawHtml' => $Excerpt['text'][1]),
				'extent' => 2,
			);
		}
	}

	protected function inlineImage($Excerpt)
	{
		if ( ! isset($Excerpt['text'][1]) or $Excerpt['text'][1] !== '[')
		{
			return;
		}

		$Excerpt['text']= substr($Excerpt['text'], 1);

		$Link = $this->inlineLink($Excerpt);

		if ($Link === null)
		{
			return;
		}

		$Inline = array(
			'extent' => $Link['extent'] + 1,
			'element' => array(
				'name' => 'img',
				'attributes' => array(
					'src' => $Link['element']['attributes']['href'],
					'alt' => $Link['element']['handler']['argument'],
				),
				'autobreak' => true,
			),
		);

		$Inline['element']['attributes'] += $Link['element']['attributes'];

		unset($Inline['element']['attributes']['href']);

		return $Inline;
	}

	protected function inlineLink($Excerpt)
	{
		$Element = array(
			'name' => 'a',
			'handler' => array(
				'function' => 'lineElements',
				'argument' => null,
				'destination' => 'elements',
			),
			'nonNestables' => array('Url', 'Link'),
			'attributes' => array(
				'href' => null,
				'title' => null,
			),
		);

		$extent = 0;

		$remainder = $Excerpt['text'];

		if (preg_match('/\[((?:[^][]++|(?R))*+)\]/', $remainder, $matches))
		{
			$Element['handler']['argument'] = $matches[1];

			$extent += strlen($matches[0]);

			$remainder = substr($remainder, $extent);
		}
		else
		{
			return;
		}

		if (preg_match('/^[(]\s*+((?:[^ ()]++|[(][^ )]+[)])++)(?:[ ]+("[^"]*+"|\'[^\']*+\'))?\s*+[)]/', $remainder, $matches))
		{
			$Element['attributes']['href'] = $matches[1];

			if (isset($matches[2]))
			{
				$Element['attributes']['title'] = substr($matches[2], 1, - 1);
			}

			$extent += strlen($matches[0]);
		}
		else
		{
			if (preg_match('/^\s*\[(.*?)\]/', $remainder, $matches))
			{
				$definition = strlen($matches[1]) ? $matches[1] : $Element['handler']['argument'];
				$definition = strtolower($definition);

				$extent += strlen($matches[0]);
			}
			else
			{
				$definition = strtolower($Element['handler']['argument']);
			}

			if ( ! isset($this->DefinitionData['Reference'][$definition]))
			{
				return;
			}

			$Definition = $this->DefinitionData['Reference'][$definition];

			$Element['attributes']['href'] = $Definition['url'];
			$Element['attributes']['title'] = $Definition['title'];
		}

		return array(
			'extent' => $extent,
			'element' => $Element,
		);
	}

	protected function inlineMarkup($Excerpt)
	{
		if ($this->markupEscaped or $this->safeMode or strpos($Excerpt['text'], '>') === false)
		{
			return;
		}

		if ($Excerpt['text'][1] === '/' and preg_match('/^<\/\w[\w-]*+[ ]*+>/s', $Excerpt['text'], $matches))
		{
			return array(
				'element' => array('rawHtml' => $matches[0]),
				'extent' => strlen($matches[0]),
			);
		}

		if ($Excerpt['text'][1] === '!' and preg_match('/^<!---?[^>-](?:-?+[^-])*-->/s', $Excerpt['text'], $matches))
		{
			return array(
				'element' => array('rawHtml' => $matches[0]),
				'extent' => strlen($matches[0]),
			);
		}

		if ($Excerpt['text'][1] !== ' ' and preg_match('/^<\w[\w-]*+(?:[ ]*+'.$this->regexHtmlAttribute.')*+[ ]*+\/?>/s', $Excerpt['text'], $matches))
		{
			return array(
				'element' => array('rawHtml' => $matches[0]),
				'extent' => strlen($matches[0]),
			);
		}
	}

	protected function inlineSpecialCharacter($Excerpt)
	{
		if (substr($Excerpt['text'], 1, 1) !== ' ' and strpos($Excerpt['text'], ';') !== false
			and preg_match('/^&(#?+[0-9a-zA-Z]++);/', $Excerpt['text'], $matches)
		) {
			return array(
				'element' => array('rawHtml' => '&' . $matches[1] . ';'),
				'extent' => strlen($matches[0]),
			);
		}

		return;
	}

	protected function inlineStrikethrough($Excerpt)
	{
		if ( ! isset($Excerpt['text'][1]))
		{
			return;
		}

		if ($Excerpt['text'][1] === '~' and preg_match('/^~~(?=\S)(.+?)(?<=\S)~~/', $Excerpt['text'], $matches))
		{
			return array(
				'extent' => strlen($matches[0]),
				'element' => array(
					'name' => 'del',
					'handler' => array(
						'function' => 'lineElements',
						'argument' => $matches[1],
						'destination' => 'elements',
					)
				),
			);
		}
	}

	protected function inlineUrl($Excerpt)
	{
		if ($this->urlsLinked !== true or ! isset($Excerpt['text'][2]) or $Excerpt['text'][2] !== '/')
		{
			return;
		}

		if (strpos($Excerpt['context'], 'http') !== false
			and preg_match('/\bhttps?+:[\/]{2}[^\s<]+\b\/*+/ui', $Excerpt['context'], $matches, PREG_OFFSET_CAPTURE)
		) {
			$url = $matches[0][0];

			$Inline = array(
				'extent' => strlen($matches[0][0]),
				'position' => $matches[0][1],
				'element' => array(
					'name' => 'a',
					'text' => $url,
					'attributes' => array(
						'href' => $url,
					),
				),
			);

			return $Inline;
		}
	}

	protected function inlineUrlTag($Excerpt)
	{
		if (strpos($Excerpt['text'], '>') !== false and preg_match('/^<(\w++:\/{2}[^ >]++)>/i', $Excerpt['text'], $matches))
		{
			$url = $matches[1];

			return array(
				'extent' => strlen($matches[0]),
				'element' => array(
					'name' => 'a',
					'text' => $url,
					'attributes' => array(
						'href' => $url,
					),
				),
			);
		}
	}

	# ~

	protected function unmarkedText($text)
	{
		$Inline = $this->inlineText($text);
		return $this->element($Inline['element']);
	}

	#
	# Handlers
	#

	protected function handle(array $Element)
	{
		if (isset($Element['handler']))
		{
			if (!isset($Element['nonNestables']))
			{
				$Element['nonNestables'] = array();
			}

			if (is_string($Element['handler']))
			{
				$function = $Element['handler'];
				$argument = $Element['text'];
				unset($Element['text']);
				$destination = 'rawHtml';
			}
			else
			{
				$function = $Element['handler']['function'];
				$argument = $Element['handler']['argument'];
				$destination = $Element['handler']['destination'];
			}

			$Element[$destination] = $this->{$function}($argument, $Element['nonNestables']);

			if ($destination === 'handler')
			{
				$Element = $this->handle($Element);
			}

			unset($Element['handler']);
		}

		return $Element;
	}

	protected function handleElementRecursive(array $Element)
	{
		return $this->elementApplyRecursive(array($this, 'handle'), $Element);
	}

	protected function handleElementsRecursive(array $Elements)
	{
		return $this->elementsApplyRecursive(array($this, 'handle'), $Elements);
	}

	protected function elementApplyRecursive($closure, array $Element)
	{
		$Element = call_user_func($closure, $Element);

		if (isset($Element['elements']))
		{
			$Element['elements'] = $this->elementsApplyRecursive($closure, $Element['elements']);
		}
		elseif (isset($Element['element']))
		{
			$Element['element'] = $this->elementApplyRecursive($closure, $Element['element']);
		}

		return $Element;
	}

	protected function elementApplyRecursiveDepthFirst($closure, array $Element)
	{
		if (isset($Element['elements']))
		{
			$Element['elements'] = $this->elementsApplyRecursiveDepthFirst($closure, $Element['elements']);
		}
		elseif (isset($Element['element']))
		{
			$Element['element'] = $this->elementsApplyRecursiveDepthFirst($closure, $Element['element']);
		}

		$Element = call_user_func($closure, $Element);

		return $Element;
	}

	protected function elementsApplyRecursive($closure, array $Elements)
	{
		foreach ($Elements as &$Element)
		{
			$Element = $this->elementApplyRecursive($closure, $Element);
		}

		return $Elements;
	}

	protected function elementsApplyRecursiveDepthFirst($closure, array $Elements)
	{
		foreach ($Elements as &$Element)
		{
			$Element = $this->elementApplyRecursiveDepthFirst($closure, $Element);
		}

		return $Elements;
	}

	protected function element(array $Element)
	{
		if ($this->safeMode)
		{
			$Element = $this->sanitiseElement($Element);
		}

		# identity map if element has no handler
		$Element = $this->handle($Element);

		$hasName = isset($Element['name']);

		$markup = '';

		if ($hasName)
		{
			$markup .= '<' . $Element['name'];

			if (isset($Element['attributes']))
			{
				foreach ($Element['attributes'] as $name => $value)
				{
					if ($value === null)
					{
						continue;
					}

					$markup .= " $name=\"".self::escape($value).'"';
				}
			}
		}

		$permitRawHtml = false;

		if (isset($Element['text']))
		{
			$text = $Element['text'];
		}
		// very strongly consider an alternative if you're writing an
		// extension
		elseif (isset($Element['rawHtml']))
		{
			$text = $Element['rawHtml'];

			$allowRawHtmlInSafeMode = isset($Element['allowRawHtmlInSafeMode']) && $Element['allowRawHtmlInSafeMode'];
			$permitRawHtml = !$this->safeMode || $allowRawHtmlInSafeMode;
		}

		$hasContent = isset($text) || isset($Element['element']) || isset($Element['elements']);

		if ($hasContent)
		{
			$markup .= $hasName ? '>' : '';

			if (isset($Element['elements']))
			{
				$markup .= $this->elements($Element['elements']);
			}
			elseif (isset($Element['element']))
			{
				$markup .= $this->element($Element['element']);
			}
			else
			{
				if (!$permitRawHtml)
				{
					$markup .= self::escape($text, true);
				}
				else
				{
					$markup .= $text;
				}
			}

			$markup .= $hasName ? '</' . $Element['name'] . '>' : '';
		}
		elseif ($hasName)
		{
			$markup .= ' />';
		}

		return $markup;
	}

	protected function elements(array $Elements)
	{
		$markup = '';

		$autoBreak = true;

		foreach ($Elements as $Element)
		{
			if (empty($Element))
			{
				continue;
			}

			$autoBreakNext = (isset($Element['autobreak'])
				? $Element['autobreak'] : isset($Element['name'])
			);
			// (autobreak === false) covers both sides of an element
			$autoBreak = !$autoBreak ? $autoBreak : $autoBreakNext;

			$markup .= ($autoBreak ? "\n" : '') . $this->element($Element);
			$autoBreak = $autoBreakNext;
		}

		$markup .= $autoBreak ? "\n" : '';

		return $markup;
	}

	# ~

	protected function li($lines)
	{
		$Elements = $this->linesElements($lines);

		if ( ! in_array('', $lines)
			and isset($Elements[0]) and isset($Elements[0]['name'])
			and $Elements[0]['name'] === 'p'
		) {
			unset($Elements[0]['name']);
		}

		return $Elements;
	}

	#
	# AST Convenience
	#

	/**
	 * Replace occurrences $regexp with $Elements in $text. Return an array of
	 * elements representing the replacement.
	 */
	protected static function pregReplaceElements($regexp, $Elements, $text)
	{
		$newElements = array();

		while (preg_match($regexp, $text, $matches, PREG_OFFSET_CAPTURE))
		{
			$offset = $matches[0][1];
			$before = substr($text, 0, $offset);
			$after = substr($text, $offset + strlen($matches[0][0]));

			$newElements[] = array('text' => $before);

			foreach ($Elements as $Element)
			{
				$newElements[] = $Element;
			}

			$text = $after;
		}

		$newElements[] = array('text' => $text);

		return $newElements;
	}

	#
	# Deprecated Methods
	#

	function parse($text)
	{
		$markup = $this->text($text);

		return $markup;
	}

	protected function sanitiseElement(array $Element)
	{
		static $goodAttribute = '/^[a-zA-Z0-9][a-zA-Z0-9-_]*+$/';
		static $safeUrlNameToAtt  = array(
			'a'   => 'href',
			'img' => 'src',
		);

		if ( ! isset($Element['name']))
		{
			unset($Element['attributes']);
			return $Element;
		}

		if (isset($safeUrlNameToAtt[$Element['name']]))
		{
			$Element = $this->filterUnsafeUrlInAttribute($Element, $safeUrlNameToAtt[$Element['name']]);
		}

		if ( ! empty($Element['attributes']))
		{
			foreach ($Element['attributes'] as $att => $val)
			{
				# filter out badly parsed attribute
				if ( ! preg_match($goodAttribute, $att))
				{
					unset($Element['attributes'][$att]);
				}
				# dump onevent attribute
				elseif (self::striAtStart($att, 'on'))
				{
					unset($Element['attributes'][$att]);
				}
			}
		}

		return $Element;
	}

	protected function filterUnsafeUrlInAttribute(array $Element, $attribute)
	{
		foreach ($this->safeLinksWhitelist as $scheme)
		{
			if (self::striAtStart($Element['attributes'][$attribute], $scheme))
			{
				return $Element;
			}
		}

		$Element['attributes'][$attribute] = str_replace(':', '%3A', $Element['attributes'][$attribute]);

		return $Element;
	}

	#
	# Static Methods
	#

	protected static function escape($text, $allowQuotes = false)
	{
		return htmlspecialchars($text, $allowQuotes ? ENT_NOQUOTES : ENT_QUOTES, 'UTF-8');
	}

	protected static function striAtStart($string, $needle)
	{
		$len = strlen($needle);

		if ($len > strlen($string))
		{
			return false;
		}
		else
		{
			return strtolower(substr($string, 0, $len)) === strtolower($needle);
		}
	}

	static function instance($name = 'default')
	{
		if (isset(self::$instances[$name]))
		{
			return self::$instances[$name];
		}

		$instance = new static();

		self::$instances[$name] = $instance;

		return $instance;
	}

	private static $instances = array();

	#
	# Fields
	#

	protected $DefinitionData;

	#
	# Read-Only

	protected $specialCharacters = array(
		'\\', '`', '*', '_', '{', '}', '[', ']', '(', ')', '>', '#', '+', '-', '.', '!', '|', '~'
	);

	protected $StrongRegex = array(
		'*' => '/^[*]{2}((?:\\\\\*|[^*]|[*][^*]*+[*])+?)[*]{2}(?![*])/s',
		'_' => '/^__((?:\\\\_|[^_]|_[^_]*+_)+?)__(?!_)/us',
	);

	protected $EmRegex = array(
		'*' => '/^[*]((?:\\\\\*|[^*]|[*][*][^*]+?[*][*])+?)[*](?![*])/s',
		'_' => '/^_((?:\\\\_|[^_]|__[^_]*__)+?)_(?!_)\b/us',
	);

	protected $regexHtmlAttribute = '[a-zA-Z_:][\w:.-]*+(?:\s*+=\s*+(?:[^"\'=<>`\s]+|"[^"]*+"|\'[^\']*+\'))?+';

	protected $voidElements = array(
		'area', 'base', 'br', 'col', 'command', 'embed', 'hr', 'img', 'input', 'link', 'meta', 'param', 'source',
	);

	protected $textLevelElements = array(
		'a', 'br', 'bdo', 'abbr', 'blink', 'nextid', 'acronym', 'basefont',
		'b', 'em', 'big', 'cite', 'small', 'spacer', 'listing',
		'i', 'rp', 'del', 'code',          'strike', 'marquee',
		'q', 'rt', 'ins', 'font',          'strong',
		's', 'tt', 'kbd', 'mark',
		'u', 'xm', 'sub', 'nobr',
				   'sup', 'ruby',
				   'var', 'span',
				   'wbr', 'time',
	);
}