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