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|
<?php
/**
* Proof-of-concept lexer that uses the PEAR package XML_HTMLSax3 to parse HTML.
*
* PEAR, not suprisingly, also has a SAX parser for HTML. I don't know
* very much about implementation, but it's fairly well written. However, that
* abstraction comes at a price: performance. You need to have it installed,
* and if the API changes, it might break our adapter. Not sure whether or not
* it's UTF-8 aware, but it has some entity parsing trouble (in all areas,
* text and attributes).
*
* Quite personally, I don't recommend using the PEAR class, and the defaults
* don't use it. The unit tests do perform the tests on the SAX parser too, but
* whatever it does for poorly formed HTML is up to it.
*
* @todo Generalize so that XML_HTMLSax is also supported.
*
* @warning Entity-resolution inside attributes is broken.
*/
class HTMLPurifier_Lexer_PEARSax3 extends HTMLPurifier_Lexer
{
/**
* Internal accumulator array for SAX parsers.
*/
protected $tokens = array();
protected $last_token_was_empty;
private $parent_handler;
private $stack = array();
public function tokenizeHTML($string, $config, $context) {
$this->tokens = array();
$this->last_token_was_empty = false;
$string = $this->normalize($string, $config, $context);
$this->parent_handler = set_error_handler(array($this, 'muteStrictErrorHandler'));
$parser = new XML_HTMLSax3();
$parser->set_object($this);
$parser->set_element_handler('openHandler','closeHandler');
$parser->set_data_handler('dataHandler');
$parser->set_escape_handler('escapeHandler');
// doesn't seem to work correctly for attributes
$parser->set_option('XML_OPTION_ENTITIES_PARSED', 1);
$parser->parse($string);
restore_error_handler();
return $this->tokens;
}
/**
* Open tag event handler, interface is defined by PEAR package.
*/
public function openHandler(&$parser, $name, $attrs, $closed) {
// entities are not resolved in attrs
foreach ($attrs as $key => $attr) {
$attrs[$key] = $this->parseData($attr);
}
if ($closed) {
$this->tokens[] = new HTMLPurifier_Token_Empty($name, $attrs);
$this->last_token_was_empty = true;
} else {
$this->tokens[] = new HTMLPurifier_Token_Start($name, $attrs);
}
$this->stack[] = $name;
return true;
}
/**
* Close tag event handler, interface is defined by PEAR package.
*/
public function closeHandler(&$parser, $name) {
// HTMLSax3 seems to always send empty tags an extra close tag
// check and ignore if you see it:
// [TESTME] to make sure it doesn't overreach
if ($this->last_token_was_empty) {
$this->last_token_was_empty = false;
return true;
}
$this->tokens[] = new HTMLPurifier_Token_End($name);
if (!empty($this->stack)) array_pop($this->stack);
return true;
}
/**
* Data event handler, interface is defined by PEAR package.
*/
public function dataHandler(&$parser, $data) {
$this->last_token_was_empty = false;
$this->tokens[] = new HTMLPurifier_Token_Text($data);
return true;
}
/**
* Escaped text handler, interface is defined by PEAR package.
*/
public function escapeHandler(&$parser, $data) {
if (strpos($data, '--') === 0) {
// remove trailing and leading double-dashes
$data = substr($data, 2);
if (strlen($data) >= 2 && substr($data, -2) == "--") {
$data = substr($data, 0, -2);
}
if (isset($this->stack[sizeof($this->stack) - 1]) &&
$this->stack[sizeof($this->stack) - 1] == "style") {
$this->tokens[] = new HTMLPurifier_Token_Text($data);
} else {
$this->tokens[] = new HTMLPurifier_Token_Comment($data);
}
$this->last_token_was_empty = false;
}
// CDATA is handled elsewhere, but if it was handled here:
//if (strpos($data, '[CDATA[') === 0) {
// $this->tokens[] = new HTMLPurifier_Token_Text(
// substr($data, 7, strlen($data) - 9) );
//}
return true;
}
/**
* An error handler that mutes strict errors
*/
public function muteStrictErrorHandler($errno, $errstr, $errfile=null, $errline=null, $errcontext=null) {
if ($errno == E_STRICT) return;
return call_user_func($this->parent_handler, $errno, $errstr, $errfile, $errline, $errcontext);
}
}
// vim: et sw=4 sts=4
|
