-<?php
-/**
- * Class HTML_To_Markdown
- *
- * A helper class to convert HTML to Markdown.
- *
- * @version 2.2.1
- * @author Nick Cernis <nick@cern.is>
- * @link https://github.com/nickcernis/html2markdown/ Latest version on GitHub.
- * @link http://twitter.com/nickcernis Nick on twitter.
- * @license http://www.opensource.org/licenses/mit-license.php MIT
- */
-class HTML_To_Markdown
-{
- /**
- * @var DOMDocument The root of the document tree that holds our HTML.
- */
- private $document;
-
- /**
- * @var string|boolean The Markdown version of the original HTML, or false if conversion failed
- */
- private $output;
-
- /**
- * @var array Class-wide options users can override.
- */
- private $options = array(
- 'header_style' => 'setext', // Set to "atx" to output H1 and H2 headers as # Header1 and ## Header2
- 'suppress_errors' => true, // Set to false to show warnings when loading malformed HTML
- 'strip_tags' => false, // Set to true to strip tags that don't have markdown equivalents. N.B. Strips tags, not their content. Useful to clean MS Word HTML output.
- 'bold_style' => '**', // Set to '__' if you prefer the underlined style
- 'italic_style' => '*', // Set to '_' if you prefer the underlined style
- 'remove_nodes' => '', // space-separated list of dom nodes that should be removed. example: "meta style script"
- );
-
-
- /**
- * Constructor
- *
- * Set up a new DOMDocument from the supplied HTML, convert it to Markdown, and store it in $this->$output.
- *
- * @param string $html The HTML to convert to Markdown.
- * @param array $overrides [optional] List of style and error display overrides.
- */
- public function __construct($html = null, $overrides = null)
- {
- if ($overrides)
- $this->options = array_merge($this->options, $overrides);
-
- if ($html)
- $this->convert($html);
- }
-
-
- /**
- * Setter for conversion options
- *
- * @param $name
- * @param $value
- */
- public function set_option($name, $value)
- {
- $this->options[$name] = $value;
- }
-
-
- /**
- * Convert
- *
- * Loads HTML and passes to get_markdown()
- *
- * @param $html
- * @return string The Markdown version of the html
- */
- public function convert($html)
- {
- $html = preg_replace('~>\s+<~', '><', $html); // Strip white space between tags to prevent creation of empty #text nodes
-
- $this->document = new DOMDocument();
-
- if ($this->options['suppress_errors'])
- libxml_use_internal_errors(true); // Suppress conversion errors (from http://bit.ly/pCCRSX )
-
- $this->document->loadHTML('<?xml encoding="UTF-8">' . $html); // Hack to load utf-8 HTML (from http://bit.ly/pVDyCt )
- $this->document->encoding = 'UTF-8';
-
- if ($this->options['suppress_errors'])
- libxml_clear_errors();
-
- return $this->get_markdown($html);
- }
-
-
- /**
- * Is Child Of?
- *
- * Is the node a child of the given parent tag?
- *
- * @param $parent_name string|array The name of the parent node(s) to search for e.g. 'code' or array('pre', 'code')
- * @param $node
- * @return bool
- */
- private static function is_child_of($parent_name, $node)
- {
- for ($p = $node->parentNode; $p != false; $p = $p->parentNode) {
- if (is_null($p))
- return false;
-
- if ( is_array($parent_name) && in_array($p->nodeName, $parent_name) )
- return true;
-
- if ($p->nodeName == $parent_name)
- return true;
- }
- return false;
- }
-
-
- /**
- * Convert Children
- *
- * Recursive function to drill into the DOM and convert each node into Markdown from the inside out.
- *
- * Finds children of each node and convert those to #text nodes containing their Markdown equivalent,
- * starting with the innermost element and working up to the outermost element.
- *
- * @param $node
- */
- private function convert_children($node)
- {
- // Don't convert HTML code inside <code> and <pre> blocks to Markdown - that should stay as HTML
- if (self::is_child_of(array('pre', 'code'), $node))
- return;
-
- // If the node has children, convert those to Markdown first
- if ($node->hasChildNodes()) {
- $length = $node->childNodes->length;
-
- for ($i = 0; $i < $length; $i++) {
- $child = $node->childNodes->item($i);
- $this->convert_children($child);
- }
- }
-
- // Now that child nodes have been converted, convert the original node
- $markdown = $this->convert_to_markdown($node);
-
- // Create a DOM text node containing the Markdown equivalent of the original node
- $markdown_node = $this->document->createTextNode($markdown);
-
- // Replace the old $node e.g. "<h3>Title</h3>" with the new $markdown_node e.g. "### Title"
- $node->parentNode->replaceChild($markdown_node, $node);
- }
-
-
- /**
- * Get Markdown
- *
- * Sends the body node to convert_children() to change inner nodes to Markdown #text nodes, then saves and
- * returns the resulting converted document as a string in Markdown format.
- *
- * @return string|boolean The converted HTML as Markdown, or false if conversion failed
- */
- private function get_markdown()
- {
- // Work on the entire DOM tree (including head and body)
- $input = $this->document->getElementsByTagName("html")->item(0);
-
- if (!$input)
- return false;
-
- // Convert all children of this root element. The DOMDocument stored in $this->doc will
- // then consist of #text nodes, each containing a Markdown version of the original node
- // that it replaced.
- $this->convert_children($input);
-
- // Sanitize and return the body contents as a string.
- $markdown = $this->document->saveHTML(); // stores the DOMDocument as a string
- $markdown = html_entity_decode($markdown, ENT_QUOTES, 'UTF-8');
- $markdown = html_entity_decode($markdown, ENT_QUOTES, 'UTF-8'); // Double decode to cover cases like &nbsp; http://www.php.net/manual/en/function.htmlentities.php#99984
- $markdown = preg_replace("/<!DOCTYPE [^>]+>/", "", $markdown); // Strip doctype declaration
- $unwanted = array('<html>', '</html>', '<body>', '</body>', '<head>', '</head>', '<?xml encoding="UTF-8">', '
');
- $markdown = str_replace($unwanted, '', $markdown); // Strip unwanted tags
- $markdown = trim($markdown, "\n\r\0\x0B");
-
- $this->output = $markdown;
-
- return $markdown;
- }
-
-
- /**
- * Convert to Markdown
- *
- * Converts an individual node into a #text node containing a string of its Markdown equivalent.
- *
- * Example: An <h3> node with text content of "Title" becomes a text node with content of "### Title"
- *
- * @param $node
- * @return string The converted HTML as Markdown
- */
- private function convert_to_markdown($node)
- {
- $tag = $node->nodeName; // the type of element, e.g. h1
- $value = $node->nodeValue; // the value of that element, e.g. The Title
-
- // Strip nodes named in remove_nodes
- $tags_to_remove = explode(' ', $this->options['remove_nodes']);
- if ( in_array($tag, $tags_to_remove) )
- return false;
-
- switch ($tag) {
- case "p":
- $markdown = (trim($value)) ? rtrim($value) . PHP_EOL . PHP_EOL : '';
- break;
- case "pre":
- $markdown = PHP_EOL . $this->convert_code($node) . PHP_EOL;
- break;
- case "h1":
- case "h2":
- $markdown = $this->convert_header($tag, $node);
- break;
- case "h3":
- $markdown = "### " . $value . PHP_EOL . PHP_EOL;
- break;
- case "h4":
- $markdown = "#### " . $value . PHP_EOL . PHP_EOL;
- break;
- case "h5":
- $markdown = "##### " . $value . PHP_EOL . PHP_EOL;
- break;
- case "h6":
- $markdown = "###### " . $value . PHP_EOL . PHP_EOL;
- break;
- case "em":
- case "i":
- case "strong":
- case "b":
- $markdown = $this->convert_emphasis($tag, $value);
- break;
- case "hr":
- $markdown = "- - - - - -" . PHP_EOL . PHP_EOL;
- break;
- case "br":
- $markdown = " " . PHP_EOL;
- break;
- case "blockquote":
- $markdown = $this->convert_blockquote($node);
- break;
- case "code":
- $markdown = $this->convert_code($node);
- break;
- case "ol":
- case "ul":
- $markdown = $value . PHP_EOL;
- break;
- case "li":
- $markdown = $this->convert_list($node);
- break;
- case "img":
- $markdown = $this->convert_image($node);
- break;
- case "a":
- $markdown = $this->convert_anchor($node);
- break;
- case "#text":
- $markdown = preg_replace('~\s+~', ' ', $value);
- $markdown = preg_replace('~^#~', '\\\\#', $markdown);
- break;
- case "#comment":
- $markdown = '';
- break;
- case "div":
- $markdown = ($this->options['strip_tags']) ? $value . PHP_EOL . PHP_EOL : html_entity_decode($node->C14N());
- break;
- default:
- // If strip_tags is false (the default), preserve tags that don't have Markdown equivalents,
- // such as <span> nodes on their own. C14N() canonicalizes the node to a string.
- // See: http://www.php.net/manual/en/domnode.c14n.php
- $markdown = ($this->options['strip_tags']) ? $value : html_entity_decode($node->C14N());
- }
-
- return $markdown;
- }
-
-
- /**
- * Convert Header
- *
- * Converts h1 and h2 headers to Markdown-style headers in setext style,
- * matching the number of underscores with the length of the title.
- *
- * e.g. Header 1 Header Two
- * ======== ----------
- *
- * Returns atx headers instead if $this->options['header_style'] is "atx"
- *
- * e.g. # Header 1 ## Header Two
- *
- * @param string $level The header level, including the "h". e.g. h1
- * @param string $node The node to convert.
- * @return string The Markdown version of the header.
- */
- private function convert_header($level, $node)
- {
- $content = $node->nodeValue;
-
- if (!$this->is_child_of('blockquote', $node) && $this->options['header_style'] == "setext") {
- $length = (function_exists('mb_strlen')) ? mb_strlen($content, 'utf-8') : strlen($content);
- $underline = ($level == "h1") ? "=" : "-";
- $markdown = $content . PHP_EOL . str_repeat($underline, $length) . PHP_EOL . PHP_EOL; // setext style
- } else {
- $prefix = ($level == "h1") ? "# " : "## ";
- $markdown = $prefix . $content . PHP_EOL . PHP_EOL; // atx style
- }
-
- return $markdown;
- }
-
-
- /**
- * Converts inline styles
- * This function is used to render strong and em tags
- *
- * eg <strong>bold text</strong> becomes **bold text** or __bold text__
- *
- * @param string $tag
- * @param string $value
- * @return string
- */
- private function convert_emphasis($tag, $value)
- {
- if ($tag == 'i' || $tag == 'em') {
- $markdown = $this->options['italic_style'] . $value . $this->options['italic_style'];
- } else {
- $markdown = $this->options['bold_style'] . $value . $this->options['bold_style'];
- }
-
- return $markdown;
- }
-
-
- /**
- * Convert Image
- *
- * Converts <img /> tags to Markdown.
- *
- * e.g. <img src="/path/img.jpg" alt="alt text" title="Title" />
- * becomes ![alt text](/path/img.jpg "Title")
- *
- * @param $node
- * @return string
- */
- private function convert_image($node)
- {
- $src = $node->getAttribute('src');
- $alt = $node->getAttribute('alt');
- $title = $node->getAttribute('title');
-
- if ($title != "") {
- $markdown = '![' . $alt . '](' . $src . ' "' . $title . '")'; // No newlines added. <img> should be in a block-level element.
- } else {
- $markdown = '![' . $alt . '](' . $src . ')';
- }
-
- return $markdown;
- }
-
-
- /**
- * Convert Anchor
- *
- * Converts <a> tags to Markdown.
- *
- * e.g. <a href="http://modernnerd.net" title="Title">Modern Nerd</a>
- * becomes [Modern Nerd](http://modernnerd.net "Title")
- *
- * @param $node
- * @return string
- */
- private function convert_anchor($node)
- {
- $href = $node->getAttribute('href');
- $title = $node->getAttribute('title');
- $text = $node->nodeValue;
-
- if ($title != "") {
- $markdown = '[' . $text . '](' . $href . ' "' . $title . '")';
- } else {
- $markdown = '[' . $text . '](' . $href . ')';
- }
-
- if (! $href)
- $markdown = html_entity_decode($node->C14N());
-
- // Append a space if the node after this one is also an anchor
- $next_node_name = $this->get_next_node_name($node);
-
- if ($next_node_name == 'a')
- $markdown = $markdown . ' ';
-
- return $markdown;
- }
-
-
- /**
- * Convert List
- *
- * Converts <ul> and <ol> lists to Markdown.
- *
- * @param $node
- * @return string
- */
- private function convert_list($node)
- {
- // If parent is an ol, use numbers, otherwise, use dashes
- $list_type = $node->parentNode->nodeName;
- $value = $node->nodeValue;
-
- if ($list_type == "ul") {
- $markdown = "- " . trim($value) . PHP_EOL;
- } else {
- $number = $this->get_position($node);
- $markdown = $number . ". " . trim($value) . PHP_EOL;
- }
-
- return $markdown;
- }
-
-
- /**
- * Convert Code
- *
- * Convert code tags by indenting blocks of code and wrapping single lines in backticks.
- *
- * @param DOMNode $node
- * @return string
- */
- private function convert_code($node)
- {
- // Store the content of the code block in an array, one entry for each line
-
- $markdown = '';
-
- $code_content = html_entity_decode($node->C14N());
- $code_content = str_replace(array("<code>", "</code>"), "", $code_content);
- $code_content = str_replace(array("<pre>", "</pre>"), "", $code_content);
-
- $lines = preg_split('/\r\n|\r|\n/', $code_content);
- $total = count($lines);
-
- // If there's more than one line of code, prepend each line with four spaces and no backticks.
- if ($total > 1 || $node->nodeName === 'pre') {
-
- // Remove the first and last line if they're empty
- $first_line = trim($lines[0]);
- $last_line = trim($lines[$total - 1]);
- $first_line = trim($first_line, "
"); //trim XML style carriage returns too
- $last_line = trim($last_line, "
");
-
- if (empty($first_line))
- array_shift($lines);
-
- if (empty($last_line))
- array_pop($lines);
-
- $count = 1;
- foreach ($lines as $line) {
- $line = str_replace('
', '', $line);
- $markdown .= " " . $line;
- // Add newlines, except final line of the code
- if ($count != $total)
- $markdown .= PHP_EOL;
- $count++;
- }
- $markdown .= PHP_EOL;
-
- } else { // There's only one line of code. It's a code span, not a block. Just wrap it with backticks.
-
- $markdown .= "`" . $lines[0] . "`";
-
- }
-
- return $markdown;
- }
-
-
- /**
- * Convert blockquote
- *
- * Prepend blockquotes with > chars.
- *
- * @param $node
- * @return string
- */
- private function convert_blockquote($node)
- {
- // Contents should have already been converted to Markdown by this point,
- // so we just need to add ">" symbols to each line.
-
- $markdown = '';
-
- $quote_content = trim($node->nodeValue);
-
- $lines = preg_split('/\r\n|\r|\n/', $quote_content);
-
- $total_lines = count($lines);
-
- foreach ($lines as $i => $line) {
- $markdown .= "> " . $line . PHP_EOL;
- if ($i + 1 == $total_lines)
- $markdown .= PHP_EOL;
- }
-
- return $markdown;
- }
-
-
- /**
- * Get Position
- *
- * Returns the numbered position of a node inside its parent
- *
- * @param $node
- * @return int The numbered position of the node, starting at 1.
- */
- private function get_position($node)
- {
- // Get all of the nodes inside the parent
- $list_nodes = $node->parentNode->childNodes;
- $total_nodes = $list_nodes->length;
-
- $position = 1;
-
- // Loop through all nodes and find the given $node
- for ($a = 0; $a < $total_nodes; $a++) {
- $current_node = $list_nodes->item($a);
-
- if ($current_node->isSameNode($node))
- $position = $a + 1;
- }
-
- return $position;
- }
-
-
- /**
- * Get Next Node Name
- *
- * Return the name of the node immediately after the passed one.
- *
- * @param $node
- * @return string|null The node name (e.g. 'h1') or null.
- */
- private function get_next_node_name($node)
- {
- $next_node_name = null;
-
- $current_position = $this->get_position($node);
- $next_node = $node->parentNode->childNodes->item($current_position);
-
- if ($next_node)
- $next_node_name = $next_node->nodeName;
-
- return $next_node_name;
- }
-
-
- /**
- * To String
- *
- * Magic method to return Markdown output when HTML_To_Markdown instance is treated as a string.
- *
- * @return string
- */
- public function __toString()
- {
- return $this->output();
- }
-
-
- /**
- * Output
- *
- * Getter for the converted Markdown contents stored in $this->output
- *
- * @return string
- */
- public function output()
- {
- if (!$this->output) {
- return '';
- } else {
- return $this->output;
- }
- }
-}