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https://github.com/renbaoshuo/S2OJ.git
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96d4a3ecf7
Due to historical reasons, the code is in subfolder "1". With SVN removal, we place the code back and remove the annoying "1" folder.
358 lines
12 KiB
PHP
358 lines
12 KiB
PHP
<?php
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/**
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* Forgivingly lexes HTML (SGML-style) markup into tokens.
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*
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* A lexer parses a string of SGML-style markup and converts them into
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* corresponding tokens. It doesn't check for well-formedness, although its
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* internal mechanism may make this automatic (such as the case of
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* HTMLPurifier_Lexer_DOMLex). There are several implementations to choose
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* from.
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*
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* A lexer is HTML-oriented: it might work with XML, but it's not
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* recommended, as we adhere to a subset of the specification for optimization
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* reasons. This might change in the future. Also, most tokenizers are not
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* expected to handle DTDs or PIs.
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*
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* This class should not be directly instantiated, but you may use create() to
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* retrieve a default copy of the lexer. Being a supertype, this class
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* does not actually define any implementation, but offers commonly used
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* convenience functions for subclasses.
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*
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* @note The unit tests will instantiate this class for testing purposes, as
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* many of the utility functions require a class to be instantiated.
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* This means that, even though this class is not runnable, it will
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* not be declared abstract.
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*
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* @par
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*
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* @note
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* We use tokens rather than create a DOM representation because DOM would:
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*
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* @par
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* -# Require more processing and memory to create,
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* -# Is not streamable, and
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* -# Has the entire document structure (html and body not needed).
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*
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* @par
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* However, DOM is helpful in that it makes it easy to move around nodes
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* without a lot of lookaheads to see when a tag is closed. This is a
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* limitation of the token system and some workarounds would be nice.
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*/
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class HTMLPurifier_Lexer
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{
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/**
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* Whether or not this lexer implements line-number/column-number tracking.
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* If it does, set to true.
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*/
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public $tracksLineNumbers = false;
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// -- STATIC ----------------------------------------------------------
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/**
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* Retrieves or sets the default Lexer as a Prototype Factory.
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*
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* By default HTMLPurifier_Lexer_DOMLex will be returned. There are
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* a few exceptions involving special features that only DirectLex
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* implements.
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*
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* @note The behavior of this class has changed, rather than accepting
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* a prototype object, it now accepts a configuration object.
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* To specify your own prototype, set %Core.LexerImpl to it.
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* This change in behavior de-singletonizes the lexer object.
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*
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* @param HTMLPurifier_Config $config
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* @return HTMLPurifier_Lexer
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* @throws HTMLPurifier_Exception
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*/
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public static function create($config)
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{
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if (!($config instanceof HTMLPurifier_Config)) {
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$lexer = $config;
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trigger_error(
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"Passing a prototype to
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HTMLPurifier_Lexer::create() is deprecated, please instead
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use %Core.LexerImpl",
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E_USER_WARNING
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);
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} else {
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$lexer = $config->get('Core.LexerImpl');
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}
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$needs_tracking =
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$config->get('Core.MaintainLineNumbers') ||
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$config->get('Core.CollectErrors');
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$inst = null;
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if (is_object($lexer)) {
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$inst = $lexer;
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} else {
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if (is_null($lexer)) {
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do {
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// auto-detection algorithm
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if ($needs_tracking) {
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$lexer = 'DirectLex';
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break;
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}
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if (class_exists('DOMDocument') &&
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method_exists('DOMDocument', 'loadHTML') &&
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!extension_loaded('domxml')
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) {
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// check for DOM support, because while it's part of the
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// core, it can be disabled compile time. Also, the PECL
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// domxml extension overrides the default DOM, and is evil
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// and nasty and we shan't bother to support it
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$lexer = 'DOMLex';
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} else {
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$lexer = 'DirectLex';
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}
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} while (0);
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} // do..while so we can break
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// instantiate recognized string names
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switch ($lexer) {
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case 'DOMLex':
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$inst = new HTMLPurifier_Lexer_DOMLex();
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break;
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case 'DirectLex':
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$inst = new HTMLPurifier_Lexer_DirectLex();
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break;
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case 'PH5P':
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$inst = new HTMLPurifier_Lexer_PH5P();
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break;
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default:
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throw new HTMLPurifier_Exception(
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"Cannot instantiate unrecognized Lexer type " .
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htmlspecialchars($lexer)
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);
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}
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}
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if (!$inst) {
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throw new HTMLPurifier_Exception('No lexer was instantiated');
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}
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// once PHP DOM implements native line numbers, or we
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// hack out something using XSLT, remove this stipulation
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if ($needs_tracking && !$inst->tracksLineNumbers) {
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throw new HTMLPurifier_Exception(
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'Cannot use lexer that does not support line numbers with ' .
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'Core.MaintainLineNumbers or Core.CollectErrors (use DirectLex instead)'
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);
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}
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return $inst;
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}
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// -- CONVENIENCE MEMBERS ---------------------------------------------
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public function __construct()
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{
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$this->_entity_parser = new HTMLPurifier_EntityParser();
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}
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/**
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* Most common entity to raw value conversion table for special entities.
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* @type array
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*/
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protected $_special_entity2str =
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array(
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'"' => '"',
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'&' => '&',
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'<' => '<',
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'>' => '>',
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''' => "'",
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''' => "'",
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''' => "'"
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);
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/**
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* Parses special entities into the proper characters.
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*
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* This string will translate escaped versions of the special characters
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* into the correct ones.
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*
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* @warning
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* You should be able to treat the output of this function as
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* completely parsed, but that's only because all other entities should
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* have been handled previously in substituteNonSpecialEntities()
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*
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* @param string $string String character data to be parsed.
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* @return string Parsed character data.
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*/
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public function parseData($string)
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{
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// following functions require at least one character
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if ($string === '') {
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return '';
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}
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// subtracts amps that cannot possibly be escaped
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$num_amp = substr_count($string, '&') - substr_count($string, '& ') -
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($string[strlen($string) - 1] === '&' ? 1 : 0);
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if (!$num_amp) {
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return $string;
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} // abort if no entities
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$num_esc_amp = substr_count($string, '&');
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$string = strtr($string, $this->_special_entity2str);
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// code duplication for sake of optimization, see above
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$num_amp_2 = substr_count($string, '&') - substr_count($string, '& ') -
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($string[strlen($string) - 1] === '&' ? 1 : 0);
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if ($num_amp_2 <= $num_esc_amp) {
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return $string;
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}
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// hmm... now we have some uncommon entities. Use the callback.
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$string = $this->_entity_parser->substituteSpecialEntities($string);
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return $string;
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}
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/**
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* Lexes an HTML string into tokens.
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* @param $string String HTML.
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* @param HTMLPurifier_Config $config
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* @param HTMLPurifier_Context $context
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* @return HTMLPurifier_Token[] array representation of HTML.
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*/
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public function tokenizeHTML($string, $config, $context)
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{
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trigger_error('Call to abstract class', E_USER_ERROR);
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}
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/**
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* Translates CDATA sections into regular sections (through escaping).
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* @param string $string HTML string to process.
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* @return string HTML with CDATA sections escaped.
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*/
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protected static function escapeCDATA($string)
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{
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return preg_replace_callback(
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'/<!\[CDATA\[(.+?)\]\]>/s',
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array('HTMLPurifier_Lexer', 'CDATACallback'),
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$string
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);
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}
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/**
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* Special CDATA case that is especially convoluted for <script>
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* @param string $string HTML string to process.
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* @return string HTML with CDATA sections escaped.
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*/
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protected static function escapeCommentedCDATA($string)
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{
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return preg_replace_callback(
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'#<!--//--><!\[CDATA\[//><!--(.+?)//--><!\]\]>#s',
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array('HTMLPurifier_Lexer', 'CDATACallback'),
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$string
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);
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}
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/**
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* Special Internet Explorer conditional comments should be removed.
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* @param string $string HTML string to process.
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* @return string HTML with conditional comments removed.
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*/
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protected static function removeIEConditional($string)
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{
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return preg_replace(
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'#<!--\[if [^>]+\]>.*?<!\[endif\]-->#si', // probably should generalize for all strings
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'',
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$string
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);
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}
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/**
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* Callback function for escapeCDATA() that does the work.
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*
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* @warning Though this is public in order to let the callback happen,
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* calling it directly is not recommended.
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* @param array $matches PCRE matches array, with index 0 the entire match
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* and 1 the inside of the CDATA section.
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* @return string Escaped internals of the CDATA section.
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*/
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protected static function CDATACallback($matches)
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{
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// not exactly sure why the character set is needed, but whatever
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return htmlspecialchars($matches[1], ENT_COMPAT, 'UTF-8');
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}
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/**
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* Takes a piece of HTML and normalizes it by converting entities, fixing
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* encoding, extracting bits, and other good stuff.
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* @param string $html HTML.
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* @param HTMLPurifier_Config $config
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* @param HTMLPurifier_Context $context
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* @return string
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* @todo Consider making protected
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*/
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public function normalize($html, $config, $context)
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{
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// normalize newlines to \n
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if ($config->get('Core.NormalizeNewlines')) {
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$html = str_replace("\r\n", "\n", $html);
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$html = str_replace("\r", "\n", $html);
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}
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if ($config->get('HTML.Trusted')) {
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// escape convoluted CDATA
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$html = $this->escapeCommentedCDATA($html);
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}
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// escape CDATA
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$html = $this->escapeCDATA($html);
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$html = $this->removeIEConditional($html);
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// extract body from document if applicable
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if ($config->get('Core.ConvertDocumentToFragment')) {
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$e = false;
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if ($config->get('Core.CollectErrors')) {
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$e =& $context->get('ErrorCollector');
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}
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$new_html = $this->extractBody($html);
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if ($e && $new_html != $html) {
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$e->send(E_WARNING, 'Lexer: Extracted body');
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}
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$html = $new_html;
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}
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// expand entities that aren't the big five
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$html = $this->_entity_parser->substituteNonSpecialEntities($html);
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// clean into wellformed UTF-8 string for an SGML context: this has
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// to be done after entity expansion because the entities sometimes
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// represent non-SGML characters (horror, horror!)
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$html = HTMLPurifier_Encoder::cleanUTF8($html);
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// if processing instructions are to removed, remove them now
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if ($config->get('Core.RemoveProcessingInstructions')) {
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$html = preg_replace('#<\?.+?\?>#s', '', $html);
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}
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return $html;
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}
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/**
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* Takes a string of HTML (fragment or document) and returns the content
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* @todo Consider making protected
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*/
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public function extractBody($html)
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{
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$matches = array();
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$result = preg_match('!<body[^>]*>(.*)</body>!is', $html, $matches);
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if ($result) {
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return $matches[1];
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} else {
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return $html;
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}
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}
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}
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// vim: et sw=4 sts=4
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