/wp-content/plugins/jetpack/_inc/lib/markdown/gfm.php

<?php

/**

 * GitHub-Flavoured Markdown. Inspired by Evan's plugin, but modified.

 *

 * @author Evan Solomon

 * @author Matt Wiebe <wiebe@automattic.com>

 * @link https://github.com/evansolomon/wp-github-flavored-markdown-comments

 *

 * Add a few extras from GitHub's Markdown implementation. Must be used in a WordPress environment.

 */



class WPCom_GHF_Markdown_Parser extends MarkdownExtra_Parser {



	/**

	 * Hooray somewhat arbitrary numbers that are fearful of 1.0.x.

	 */

	const WPCOM_GHF_MARDOWN_VERSION = '0.9.0';



	/**

	 * Use a [code] shortcode when encountering a fenced code block

	 * @var boolean

	 */

	public $use_code_shortcode = true;



	/**

	 * Preserve shortcodes, untouched by Markdown.

	 * This requires use within a WordPress installation.

	 * @var boolean

	 */

	public $preserve_shortcodes = true;



	/**

	 * Preserve the legacy $latex your-latex-code-here$ style

	 * LaTeX markup

	 */

	public $preserve_latex = true;



	/**

	 * Preserve single-line <code> blocks.

	 * @var boolean

	 */

	public $preserve_inline_code_blocks = true;



	/**

	 * Strip paragraphs from the output. This is the right default for WordPress,

	 * which generally wants to create its own paragraphs with `wpautop`

	 * @var boolean

	 */

	public $strip_paras = true;



	// Will run through sprintf - you can supply your own syntax if you want

	public $shortcode_start = '[code lang=%s]';

	public $shortcode_end   = '[/code]';



	// Stores shortcodes we remove and then replace

	protected $preserve_text_hash = array();



	/**

	 * Set environment defaults based on presence of key functions/classes.

	 */

	public function __construct() {

		$this->use_code_shortcode  = class_exists( 'SyntaxHighlighter' );

		$this->preserve_shortcodes = function_exists( 'get_shortcode_regex' );

		$this->preserve_latex      = function_exists( 'latex_markup' );

		$this->strip_paras         = function_exists( 'wpautop' );



		parent::MarkdownExtra_Parser();

	}



	/**

	 * Overload to specify heading styles only if the hash has space(s) after it. This is actually in keeping with

	 * the documentation and eases the semantic overload of the hash character.

	 * #Will Not Produce a Heading 1

	 * # This Will Produce a Heading 1

	 *

	 * @param  string $text Markdown text

	 * @return string       HTML-transformed text

	 */

	public function transform( $text ) {

		// Preserve anything inside a single-line <code> element

		if ( $this->preserve_inline_code_blocks ) {

			$text = $this->single_line_code_preserve( $text );

		}

		// Remove all shortcodes so their interiors are left intact

		if ( $this->preserve_shortcodes ) {

			$text = $this->shortcode_preserve( $text );

		}

		// Remove legacy LaTeX so it's left intact

		if ( $this->preserve_latex ) {

			$text = $this->latex_preserve( $text );

		}



		// escape line-beginning # chars that do not have a space after them.

		$text = preg_replace_callback( '|^#{1,6}( )?|um', array( $this, '_doEscapeForHashWithoutSpacing' ), $text );



		// run through core Markdown

		$text = parent::transform( $text );



		// Occasionally Markdown Extra chokes on a para structure, producing odd paragraphs.

		$text = str_replace( "<p>&lt;</p>\n\n<p>p>", '<p>', $text );



		// put start-of-line # chars back in place

		$text = $this->restore_leading_hash( $text );



		// Strip paras if set

		if ( $this->strip_paras ) {

			$text = $this->unp( $text );

		}



		// Restore preserved things like shortcodes/LaTeX

		$text = $this->do_restore( $text );



		return $text;

	}



	/**

	 * Prevents blocks like <code>__this__</code> from turning into <code><strong>this</strong></code>

	 * @param  string $text Text that may need preserving

	 * @return string       Text that was preserved if needed

	 */

	public function single_line_code_preserve( $text ) {

		return preg_replace_callback( '|<code\b[^>]*>(.*?)</code>|', array( $this, 'do_single_line_code_preserve' ), $text );

	}



	/**

	 * Regex callback for inline code presevation

	 * @param  array $matches Regex matches

	 * @return string         Hashed content for later restoration

	 */

	public function do_single_line_code_preserve( $matches ) {

		return '<code>' . $this->hash_block( $matches[1] ) . '</code>';

	}



	/**

	 * Preserve code block contents by HTML encoding them. Useful before getting to KSES stripping.

	 * @param  string $text Markdown/HTML content

	 * @return string       Markdown/HTML content with escaped code blocks

	 */

	public function codeblock_preserve( $text ) {

		return preg_replace_callback( "/^([`~]{3})([^`\n]+)?\n([^`~]+)(\\1)/m", array( $this, 'do_codeblock_preserve' ), $text );

	}



	/**

	 * Regex callback for code block preservation.

	 * @param  array $matches Regex matches

	 * @return string         Codeblock with escaped interior

	 */

	public function do_codeblock_preserve( $matches ) {

		$block = stripslashes( $matches[3] );

		$block = esc_html( $block );

		$open = $matches[1] . $matches[2] . "\n";

		return $open . $block . $matches[4];

	}



	/**

	 * Restore previously preserved (i.e. escaped) code block contents.

	 * @param  string $text Markdown/HTML content with escaped code blocks

	 * @return string       Markdown/HTML content

	 */

	public function codeblock_restore( $text ) {

		return preg_replace_callback( "/^([`~]{3})([^`\n]+)?\n([^`~]+)(\\1)/m", array( $this, 'do_codeblock_restore' ), $text );

	}



	/**

	 * Regex callback for code block restoration (unescaping).

	 * @param  array $matches Regex matches

	 * @return string         Codeblock with unescaped interior

	 */

	public function do_codeblock_restore( $matches ) {

		$block = html_entity_decode( $matches[3], ENT_QUOTES );

		$open = $matches[1] . $matches[2] . "\n";

		return $open . $block . $matches[4];

	}



	/**

	 * Called to preserve legacy LaTeX like $latex some-latex-text $

	 * @param  string $text Text in which to preserve LaTeX

	 * @return string       Text with LaTeX replaced by a hash that will be restored later

	 */

	protected function latex_preserve( $text ) {

		// regex from latex_remove()

		$regex = '%

			\$latex(?:=\s*|\s+)

			((?:

				[^$]+ # Not a dollar

			|

				(?<=(?<!\\\\)\\\\)\$ # Dollar preceded by exactly one slash

			)+)

			(?<!\\\\)\$ # Dollar preceded by zero slashes

		%ix';

		$text = preg_replace_callback( $regex, array( $this, '_doRemoveText'), $text );

		return $text;

	}



	/**

	 * Called to preserve WP shortcodes from being formatted by Markdown in any way.

	 * @param  string $text Text in which to preserve shortcodes

	 * @return string       Text with shortcodes replaced by a hash that will be restored later

	 */

	protected function shortcode_preserve( $text ) {

		$text = preg_replace_callback( $this->get_shortcode_regex(), array( $this, '_doRemoveText' ), $text );

		return $text;

	}



	/**

	 * Restores any text preserved by $this->hash_block()

	 * @param  string $text Text that may have hashed preservation placeholders

	 * @return string       Text with hashed preseravtion placeholders replaced by original text

	 */

	protected function do_restore( $text ) {

		foreach( $this->preserve_text_hash as $hash => $value ) {

			$placeholder = $this->hash_maker( $hash );

			$text = str_replace( $placeholder, $value, $text );

		}

		// reset the hash

		$this->preserve_text_hash = array();

		return $text;

	}



	/**

	 * Regex callback for text preservation

	 * @param  array $m  Regex $matches array

	 * @return string    A placeholder that will later be replaced by the original text

	 */

	protected function _doRemoveText( $m ) {

		return $this->hash_block( $m[0] );

	}



	/**

	 * Call this to store a text block for later restoration.

	 * @param  string $text Text to preserve for later

	 * @return string       Placeholder that will be swapped out later for the original text

	 */

	protected function hash_block( $text ) {

		$hash = md5( $text );

		$this->preserve_text_hash[ $hash ] = $text;

		$placeholder = $this->hash_maker( $hash );

		return $placeholder;

	}



	/**

	 * Less glamorous than the Keymaker

	 * @param  string $hash An md5 hash

	 * @return string       A placeholder hash

	 */

	protected function hash_maker( $hash ) {

		return 'MARKDOWN_HASH' . $hash . 'MARKDOWN_HASH';

	}



	/**

	 * Remove bare <p> elements. <p>s with attributes will be preserved.

	 * @param  string $text HTML content

	 * @return string       <p>-less content

	 */

	public function unp( $text ) {

		return preg_replace( "#<p>(.*?)</p>(\n|$)#ums", '$1$2', $text );

	}



	/**

	 * A regex of all shortcodes currently registered by the current

	 * WordPress installation

	 * @uses   get_shortcode_regex()

	 * @return string A regex for grabbing shortcodes.

	 */

	protected function get_shortcode_regex() {

		$pattern = get_shortcode_regex();

		

		// don't match markdown link anchors that could be mistaken for shortcodes.

		$pattern .= '(?!\()'; 

		

		return "/$pattern/s";

	}



	/**

	 * Since we escape unspaced #Headings, put things back later.

	 * @param  string $text text with a leading escaped hash

	 * @return string       text with leading hashes unescaped

	 */

	protected function restore_leading_hash( $text ) {

		return preg_replace( "/^(<p>)?(&#35;|\\\\#)/um", "$1#", $text );

	}



	/**

	 * Overload to support ```-fenced code blocks for pre-Markdown Extra 1.2.8

	 * https://help.github.com/articles/github-flavored-markdown#fenced-code-blocks

	 */

	public function doFencedCodeBlocks( $text ) {

		// If we're at least at 1.2.8, native fenced code blocks are in.

		// Below is just copied from it in case we somehow got loaded on

		// top of someone else's Markdown Extra

		if ( version_compare( MARKDOWNEXTRA_VERSION, '1.2.8', '>=' ) )

			return parent::doFencedCodeBlocks( $text );



		#

		# Adding the fenced code block syntax to regular Markdown:

		#

		# ~~~

		# Code block

		# ~~~

		#

		$less_than_tab = $this->tab_width;



		$text = preg_replace_callback('{

				(?:\n|\A)

				# 1: Opening marker

				(

					(?:~{3,}|`{3,}) # 3 or more tildes/backticks.

				)

				[ ]*

				(?:

					\.?([-_:a-zA-Z0-9]+) # 2: standalone class name

				|

					'.$this->id_class_attr_catch_re.' # 3: Extra attributes

				)?

				[ ]* \n # Whitespace and newline following marker.



				# 4: Content

				(

					(?>

						(?!\1 [ ]* \n)	# Not a closing marker.

						.*\n+

					)+

				)



				# Closing marker.

				\1 [ ]* (?= \n )

			}xm',

			array($this, '_doFencedCodeBlocks_callback'), $text);



		return $text;

	}



	/**

	 * Callback for pre-processing start of line hashes to slyly escape headings that don't

	 * have a leading space

	 * @param  array $m  preg_match matches

	 * @return string    possibly escaped start of line hash

	 */

	public function _doEscapeForHashWithoutSpacing( $m ) {

		if ( ! isset( $m[1] ) )

			$m[0] = '\\' . $m[0];

		return $m[0];

	}



	/**

	 * Overload to support Viper's [code] shortcode. Because awesome.

	 */

	public function _doFencedCodeBlocks_callback( $matches ) {

		// in case we have some escaped leading hashes right at the start of the block

		$matches[4] = $this->restore_leading_hash( $matches[4] );

		// just MarkdownExtra_Parser if we're not going ultra-deluxe

		if ( ! $this->use_code_shortcode ) {

			return parent::_doFencedCodeBlocks_callback( $matches );

		}



		// default to a "text" class if one wasn't passed. Helps with encoding issues later.

		if ( empty( $matches[2] ) ) {

			$matches[2] = 'text';

		}



		$classname =& $matches[2];

		$codeblock = preg_replace_callback('/^\n+/', array( $this, '_doFencedCodeBlocks_newlines' ), $matches[4] );



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

			$classname = substr( $classname, 1 );



		$codeblock = esc_html( $codeblock );

		$codeblock = sprintf( $this->shortcode_start, $classname ) . "\n{$codeblock}" . $this->shortcode_end;

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

	}



}