<?php
/**
* Parser that uses PHP 5's DOM extension (part of the core).
*
* In PHP 5, the DOM XML extension was revamped into DOM and added to the core.
* It gives us a forgiving HTML parser, which we use to transform the HTML
* into a DOM, and then into the tokens. It is blazingly fast (for large
* documents, it performs twenty times faster than
* HTMLPurifier_Lexer_DirectLex,and is the default choice for PHP 5.
*
* @note Any empty elements will have empty tokens associated with them, even if
* this is prohibited by the spec. This is cannot be fixed until the spec
* comes into play.
*
* @note PHP's DOM extension does not actually parse any entities, we use
* our own function to do that.
*
* @warning DOM tends to drop whitespace, which may wreak havoc on indenting.
* If this is a huge problem, due to the fact that HTML is hand
* edited and you are unable to get a parser cache that caches the
* the output of HTML Purifier while keeping the original HTML lying
* around, you may want to run Tidy on the resulting output or use
* HTMLPurifier_DirectLex
*/
class HTMLPurifier_Lexer_DOMLex extends HTMLPurifier_Lexer
{
private $factory;
public function __construct() {
// setup the factory
parent::__construct();
$this->factory = new HTMLPurifier_TokenFactory();
}
public function tokenizeHTML($html, $config, $context) {
$html = $this->normalize($html, $config, $context);
// attempt to armor stray angled brackets that cannot possibly
// form tags and thus are probably being used as emoticons
if ($config->get('Core.AggressivelyFixLt')) {
$char = '[^a-z!\/]';
$comment = "/<!--(.*?)(-->|\z)/is";
$html = preg_replace_callback($comment, array($this, 'callbackArmorCommentEntities'), $html);
do {
$old = $html;
$html = preg_replace("/<($char)/i", '<\\1', $html);
} while ($html !== $old);
$html = preg_replace_callback($comment, array($this, 'callbackUndoCommentSubst'), $html); // fix comments
}
// preprocess html, essential for UTF-8
$html = $this->wrapHTML($html, $config, $context);
$doc = new DOMDocument();
$doc->encoding = 'UTF-8'; // theoretically, the above has this covered
set_error_handler(array($this, 'muteErrorHandler'));
$doc->loadHTML($html);
restore_error_handler();
$tokens = array();
$this->tokenizeDOM(
$doc->getElementsByTagName('html')->item(0)-> // <html>
getElementsByTagName('body')->item(0)-> // <body>
getElementsByTagName('div')->item(0) // <div>
, $tokens);
return $tokens;
}
/**
* Recursive function that tokenizes a node, putting it into an accumulator.
*
* @param $node DOMNode to be tokenized.
* @param $tokens Array-list of already tokenized tokens.
* @param $collect Says whether or start and close are collected, set to
* false at first recursion because it's the implicit DIV
* tag you're dealing with.
* @returns Tokens of node appended to previously passed tokens.
*/
protected function tokenizeDOM($node, &$tokens, $collect = false) {
// intercept non element nodes. WE MUST catch all of them,
// but we're not getting the character reference nodes because
// those should have been preprocessed
if ($node->nodeType === XML_TEXT_NODE) {
$tokens[] = $this->factory->createText($node->data);
return;
} elseif ($node->nodeType === XML_CDATA_SECTION_NODE) {
// undo libxml's special treatment of <script> and <style> tags
$last = end($tokens);
$data = $node->data;
// (note $node->tagname is already normalized)
if ($last instanceof HTMLPurifier_Token_Start && ($last->name == 'script' || $last->name == 'style')) {
$new_data = trim($data);
if (substr($new_data, 0, 4) === '<!--') {
$data = substr($new_data, 4);
if (substr($data, -3) === '-->') {
$data = substr($data, 0, -3);
} else {
// Highly suspicious! Not sure what to do...
}
}
}
$tokens[] = $this->factory->createText($this->parseData($data));
return;
} elseif ($node->nodeType === XML_COMMENT_NODE) {
// this is code is only invoked for comments in script/style in versions
// of libxml pre-2.6.28 (regular comments, of course, are still
// handled regularly)
$tokens[] = $this->factory->createComment($node->data);
return;
} elseif (
// not-well tested: there may be other nodes we have to grab
$node->nodeType !== XML_ELEMENT_NODE
) {
return;
}
$attr = $node->hasAttributes() ?
$this->transformAttrToAssoc($node->attributes) :
array();
// We still have to make sure that the element actually IS empty
if (!$node->childNodes->length) {
if ($collect) {
$tokens[] = $this->factory->createEmpty($node->tagName, $attr);
}
} else {
if ($collect) { // don't wrap on first iteration
$tokens[] = $this->factory->createStart(
$tag_name = $node->tagName, // somehow, it get's dropped
$attr
);
}
foreach ($node->childNodes as $node) {
// remember, it's an accumulator. Otherwise, we'd have
// to use array_merge
$this->tokenizeDOM($node, $tokens, true);
}
if ($collect) {
$tokens[] = $this->factory->createEnd($tag_name);
}
}
}
/**
* Converts a DOMNamedNodeMap of DOMAttr objects into an assoc array.
*
* @param $attribute_list DOMNamedNodeMap of DOMAttr objects.
* @returns Associative array of attributes.
*/
protected function transformAttrToAssoc($node_map) {
// NamedNodeMap is documented very well, so we're using undocumented
// features, namely, the fact that it implements Iterator and
// has a ->length attribute
if ($node_map->length === 0) return array();
$array = array();
foreach ($node_map as $attr) {
$array[$attr->name] = $attr->value;
}
return $array;
}
/**
* An error handler that mutes all errors
*/
public function muteErrorHandler($errno, $errstr) {}
/**
* Callback function for undoing escaping of stray angled brackets
* in comments
*/
public function callbackUndoCommentSubst($matches) {
return '<!--' . strtr($matches[1], array('&'=>'&','<'=>'<')) . $matches[2];
}
/**
* Callback function that entity-izes ampersands in comments so that
* callbackUndoCommentSubst doesn't clobber them
*/
public function callbackArmorCommentEntities($matches) {
return '<!--' . str_replace('&', '&', $matches[1]) . $matches[2];
}
/**
* Wraps an HTML fragment in the necessary HTML
*/
protected function wrapHTML($html, $config, $context) {
$def = $config->getDefinition('HTML');
$ret = '';
if (!empty($def->doctype->dtdPublic) || !empty($def->doctype->dtdSystem)) {
$ret .= '<!DOCTYPE html ';
if (!empty($def->doctype->dtdPublic)) $ret .= 'PUBLIC "' . $def->doctype->dtdPublic . '" ';
if (!empty($def->doctype->dtdSystem)) $ret .= '"' . $def->doctype->dtdSystem . '" ';
$ret .= '>';
}
$ret .= '<html><head>';
$ret .= '<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />';
// No protection if $html contains a stray </div>!
$ret .= '</head><body><div>'.$html.'</div></body></html>';
return $ret;
}
}
// vim: et sw=4 sts=4
