389 lines
12 KiB
PHP
389 lines
12 KiB
PHP
<?php
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/**
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* GitHub-Flavoured Markdown. Inspired by Evan's plugin, but modified.
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*
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* @author Evan Solomon
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* @author Matt Wiebe <wiebe@automattic.com>
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* @link https://github.com/evansolomon/wp-github-flavored-markdown-comments
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*
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* Add a few extras from GitHub's Markdown implementation. Must be used in a WordPress environment.
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*/
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class WPCom_GHF_Markdown_Parser extends MarkdownExtra_Parser {
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/**
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* Hooray somewhat arbitrary numbers that are fearful of 1.0.x.
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*/
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const WPCOM_GHF_MARDOWN_VERSION = '0.9.0';
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/**
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* Use a [code] shortcode when encountering a fenced code block
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* @var boolean
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*/
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public $use_code_shortcode = true;
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/**
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* Preserve shortcodes, untouched by Markdown.
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* This requires use within a WordPress installation.
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* @var boolean
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*/
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public $preserve_shortcodes = true;
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/**
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* Preserve the legacy $latex your-latex-code-here$ style
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* LaTeX markup
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*/
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public $preserve_latex = true;
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/**
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* Preserve single-line <code> blocks.
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* @var boolean
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*/
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public $preserve_inline_code_blocks = true;
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/**
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* Strip paragraphs from the output. This is the right default for WordPress,
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* which generally wants to create its own paragraphs with `wpautop`
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* @var boolean
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*/
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public $strip_paras = true;
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// Will run through sprintf - you can supply your own syntax if you want
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public $shortcode_start = '[code lang=%s]';
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public $shortcode_end = '[/code]';
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// Stores shortcodes we remove and then replace
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protected $preserve_text_hash = array();
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/**
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* Set environment defaults based on presence of key functions/classes.
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*/
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public function __construct() {
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$this->use_code_shortcode = class_exists( 'SyntaxHighlighter' );
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$this->preserve_shortcodes = function_exists( 'get_shortcode_regex' );
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$this->preserve_latex = function_exists( 'latex_markup' );
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$this->strip_paras = function_exists( 'wpautop' );
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parent::__construct();
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}
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/**
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* Overload to specify heading styles only if the hash has space(s) after it. This is actually in keeping with
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* the documentation and eases the semantic overload of the hash character.
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* #Will Not Produce a Heading 1
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* # This Will Produce a Heading 1
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*
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* @param string $text Markdown text
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* @return string HTML-transformed text
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*/
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public function transform( $text ) {
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// Preserve anything inside a single-line <code> element
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if ( $this->preserve_inline_code_blocks ) {
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$text = $this->single_line_code_preserve( $text );
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}
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// Remove all shortcodes so their interiors are left intact
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if ( $this->preserve_shortcodes ) {
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$text = $this->shortcode_preserve( $text );
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}
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// Remove legacy LaTeX so it's left intact
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if ( $this->preserve_latex ) {
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$text = $this->latex_preserve( $text );
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}
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// escape line-beginning # chars that do not have a space after them.
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$text = preg_replace_callback( '|^#{1,6}( )?|um', array( $this, '_doEscapeForHashWithoutSpacing' ), $text );
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/**
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* Allow third-party plugins to define custom patterns that won't be processed by Markdown.
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*
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* @module markdown
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*
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* @since 3.9.2
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*
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* @param array $custom_patterns Array of custom patterns to be ignored by Markdown.
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*/
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$custom_patterns = apply_filters( 'jetpack_markdown_preserve_pattern', array() );
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if ( is_array( $custom_patterns ) && ! empty( $custom_patterns ) ) {
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foreach ( $custom_patterns as $pattern ) {
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$text = preg_replace_callback( $pattern, array( $this, '_doRemoveText'), $text );
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}
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}
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// run through core Markdown
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$text = parent::transform( $text );
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// Occasionally Markdown Extra chokes on a para structure, producing odd paragraphs.
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$text = str_replace( "<p><</p>\n\n<p>p>", '<p>', $text );
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// put start-of-line # chars back in place
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$text = $this->restore_leading_hash( $text );
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// Strip paras if set
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if ( $this->strip_paras ) {
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$text = $this->unp( $text );
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}
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// Restore preserved things like shortcodes/LaTeX
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$text = $this->do_restore( $text );
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return $text;
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}
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/**
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* Prevents blocks like <code>__this__</code> from turning into <code><strong>this</strong></code>
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* @param string $text Text that may need preserving
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* @return string Text that was preserved if needed
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*/
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public function single_line_code_preserve( $text ) {
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return preg_replace_callback( '|<code\b[^>]*>(.*?)</code>|', array( $this, 'do_single_line_code_preserve' ), $text );
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}
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/**
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* Regex callback for inline code presevation
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* @param array $matches Regex matches
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* @return string Hashed content for later restoration
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*/
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public function do_single_line_code_preserve( $matches ) {
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return '<code>' . $this->hash_block( $matches[1] ) . '</code>';
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}
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/**
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* Preserve code block contents by HTML encoding them. Useful before getting to KSES stripping.
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* @param string $text Markdown/HTML content
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* @return string Markdown/HTML content with escaped code blocks
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*/
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public function codeblock_preserve( $text ) {
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return preg_replace_callback( "/^([`~]{3})([^`\n]+)?\n([^`~]+)(\\1)/m", array( $this, 'do_codeblock_preserve' ), $text );
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}
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/**
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* Regex callback for code block preservation.
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* @param array $matches Regex matches
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* @return string Codeblock with escaped interior
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*/
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public function do_codeblock_preserve( $matches ) {
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$block = stripslashes( $matches[3] );
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$block = esc_html( $block );
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$block = str_replace( '\\', '\\\\', $block );
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$open = $matches[1] . $matches[2] . "\n";
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return $open . $block . $matches[4];
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}
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/**
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* Restore previously preserved (i.e. escaped) code block contents.
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* @param string $text Markdown/HTML content with escaped code blocks
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* @return string Markdown/HTML content
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*/
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public function codeblock_restore( $text ) {
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return preg_replace_callback( "/^([`~]{3})([^`\n]+)?\n([^`~]+)(\\1)/m", array( $this, 'do_codeblock_restore' ), $text );
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}
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/**
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* Regex callback for code block restoration (unescaping).
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* @param array $matches Regex matches
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* @return string Codeblock with unescaped interior
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*/
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public function do_codeblock_restore( $matches ) {
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$block = html_entity_decode( $matches[3], ENT_QUOTES );
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$open = $matches[1] . $matches[2] . "\n";
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return $open . $block . $matches[4];
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}
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/**
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* Called to preserve legacy LaTeX like $latex some-latex-text $
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* @param string $text Text in which to preserve LaTeX
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* @return string Text with LaTeX replaced by a hash that will be restored later
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*/
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protected function latex_preserve( $text ) {
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// regex from latex_remove()
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$regex = '%
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\$latex(?:=\s*|\s+)
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((?:
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[^$]+ # Not a dollar
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(?<=(?<!\\\\)\\\\)\$ # Dollar preceded by exactly one slash
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)+)
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(?<!\\\\)\$ # Dollar preceded by zero slashes
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%ix';
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$text = preg_replace_callback( $regex, array( $this, '_doRemoveText'), $text );
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return $text;
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}
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/**
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* Called to preserve WP shortcodes from being formatted by Markdown in any way.
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* @param string $text Text in which to preserve shortcodes
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* @return string Text with shortcodes replaced by a hash that will be restored later
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*/
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protected function shortcode_preserve( $text ) {
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$text = preg_replace_callback( $this->get_shortcode_regex(), array( $this, '_doRemoveText' ), $text );
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return $text;
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}
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/**
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* Restores any text preserved by $this->hash_block()
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* @param string $text Text that may have hashed preservation placeholders
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* @return string Text with hashed preseravtion placeholders replaced by original text
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*/
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protected function do_restore( $text ) {
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foreach( $this->preserve_text_hash as $hash => $value ) {
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$placeholder = $this->hash_maker( $hash );
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$text = str_replace( $placeholder, $value, $text );
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}
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// reset the hash
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$this->preserve_text_hash = array();
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return $text;
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}
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/**
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* Regex callback for text preservation
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* @param array $m Regex $matches array
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* @return string A placeholder that will later be replaced by the original text
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*/
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protected function _doRemoveText( $m ) {
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return $this->hash_block( $m[0] );
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}
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/**
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* Call this to store a text block for later restoration.
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* @param string $text Text to preserve for later
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* @return string Placeholder that will be swapped out later for the original text
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*/
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protected function hash_block( $text ) {
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$hash = md5( $text );
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$this->preserve_text_hash[ $hash ] = $text;
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$placeholder = $this->hash_maker( $hash );
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return $placeholder;
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}
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/**
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* Less glamorous than the Keymaker
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* @param string $hash An md5 hash
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* @return string A placeholder hash
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*/
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protected function hash_maker( $hash ) {
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return 'MARKDOWN_HASH' . $hash . 'MARKDOWN_HASH';
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}
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/**
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* Remove bare <p> elements. <p>s with attributes will be preserved.
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* @param string $text HTML content
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* @return string <p>-less content
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*/
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public function unp( $text ) {
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return preg_replace( "#<p>(.*?)</p>(\n|$)#ums", '$1$2', $text );
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}
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/**
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* A regex of all shortcodes currently registered by the current
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* WordPress installation
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* @uses get_shortcode_regex()
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* @return string A regex for grabbing shortcodes.
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*/
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protected function get_shortcode_regex() {
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$pattern = get_shortcode_regex();
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// don't match markdown link anchors that could be mistaken for shortcodes.
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$pattern .= '(?!\()';
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return "/$pattern/s";
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}
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/**
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* Since we escape unspaced #Headings, put things back later.
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* @param string $text text with a leading escaped hash
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* @return string text with leading hashes unescaped
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*/
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protected function restore_leading_hash( $text ) {
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return preg_replace( "/^(<p>)?(#|\\\\#)/um", "$1#", $text );
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}
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/**
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* Overload to support ```-fenced code blocks for pre-Markdown Extra 1.2.8
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* https://help.github.com/articles/github-flavored-markdown#fenced-code-blocks
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*/
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public function doFencedCodeBlocks( $text ) {
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// If we're at least at 1.2.8, native fenced code blocks are in.
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// Below is just copied from it in case we somehow got loaded on
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// top of someone else's Markdown Extra
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if ( version_compare( MARKDOWNEXTRA_VERSION, '1.2.8', '>=' ) )
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return parent::doFencedCodeBlocks( $text );
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#
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# Adding the fenced code block syntax to regular Markdown:
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#
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# ~~~
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# Code block
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# ~~~
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#
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$less_than_tab = $this->tab_width;
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$text = preg_replace_callback('{
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(?:\n|\A)
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# 1: Opening marker
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(
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(?:~{3,}|`{3,}) # 3 or more tildes/backticks.
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)
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[ ]*
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(?:
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\.?([-_:a-zA-Z0-9]+) # 2: standalone class name
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'.$this->id_class_attr_catch_re.' # 3: Extra attributes
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)?
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[ ]* \n # Whitespace and newline following marker.
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# 4: Content
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(
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(?>
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(?!\1 [ ]* \n) # Not a closing marker.
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.*\n+
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)+
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)
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# Closing marker.
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\1 [ ]* (?= \n )
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}xm',
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array($this, '_doFencedCodeBlocks_callback'), $text);
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return $text;
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}
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/**
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* Callback for pre-processing start of line hashes to slyly escape headings that don't
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* have a leading space
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* @param array $m preg_match matches
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* @return string possibly escaped start of line hash
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*/
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public function _doEscapeForHashWithoutSpacing( $m ) {
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if ( ! isset( $m[1] ) )
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$m[0] = '\\' . $m[0];
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return $m[0];
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}
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/**
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* Overload to support Viper's [code] shortcode. Because awesome.
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*/
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public function _doFencedCodeBlocks_callback( $matches ) {
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// in case we have some escaped leading hashes right at the start of the block
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$matches[4] = $this->restore_leading_hash( $matches[4] );
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// just MarkdownExtra_Parser if we're not going ultra-deluxe
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if ( ! $this->use_code_shortcode ) {
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return parent::_doFencedCodeBlocks_callback( $matches );
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}
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// default to a "text" class if one wasn't passed. Helps with encoding issues later.
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if ( empty( $matches[2] ) ) {
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$matches[2] = 'text';
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}
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$classname =& $matches[2];
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$codeblock = preg_replace_callback('/^\n+/', array( $this, '_doFencedCodeBlocks_newlines' ), $matches[4] );
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if ( $classname{0} == '.' )
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$classname = substr( $classname, 1 );
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$codeblock = esc_html( $codeblock );
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$codeblock = sprintf( $this->shortcode_start, $classname ) . "\n{$codeblock}" . $this->shortcode_end;
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return "\n\n" . $this->hashBlock( $codeblock ). "\n\n";
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}
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}
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