<?php

#
#
# 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.
#
#

if (! class_exists( 'Redux_Parsedown' ) ) {
	class Redux_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',
		);
	}
}
