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<?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' );
/**
* Allow processing shortcode contents.
*
* @module markdown
*
* @since 4.4.0
*
* @param boolean $preserve_shortcodes Defaults to $this->preserve_shortcodes.
*/
$this->preserve_shortcodes = apply_filters( 'jetpack_markdown_preserve_shortcodes', $this->preserve_shortcodes ) && function_exists( 'get_shortcode_regex' );
$this->preserve_latex = function_exists( 'latex_markup' );
$this->strip_paras = function_exists( 'wpautop' );
parent::__construct();
}
/**
* 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 );
}
// Do not process characters inside URLs.
$text = $this->urls_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 );
/**
* Allow third-party plugins to define custom patterns that won't be processed by Markdown.
*
* @module markdown
*
* @since 3.9.2
*
* @param array $custom_patterns Array of custom patterns to be ignored by Markdown.
*/
$custom_patterns = apply_filters( 'jetpack_markdown_preserve_pattern', array() );
if ( is_array( $custom_patterns ) && ! empty( $custom_patterns ) ) {
foreach ( $custom_patterns as $pattern ) {
$text = preg_replace_callback( $pattern, array( $this, '_doRemoveText'), $text );
}
}
// run through core Markdown
$text = parent::transform( $text );
// Occasionally Markdown Extra chokes on a para structure, producing odd paragraphs.
$text = str_replace( "<p><</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 );
$block = str_replace( '\\', '\\\\', $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;
}
/**
* Avoid characters inside URLs from being formatted by Markdown in any way.
*
* @param string $text Text in which to preserve URLs.
*
* @return string Text with URLs replaced by a hash that will be restored later.
*/
protected function urls_preserve( $text ) {
$text = preg_replace_callback(
'#(?<!<)(?:https?|ftp)://([^\s<>"\'\[\]()]+|\[(?1)*+\]|\((?1)*+\))+(?<![_*.?])#i',
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 ) {
// Reverse hashes to ensure nested blocks are restored.
$hashes = array_reverse( $this->preserve_text_hash, true );
foreach( $hashes 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>)?(#|\\\\#)/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";
}
}