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https://github.com/ezyang/htmlpurifier.git
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5b3431d889
- Some Lexer things were moved around git-svn-id: http://htmlpurifier.org/svnroot/htmlpurifier/trunk@1469 48356398-32a2-884e-a903-53898d9a118a
360 lines
13 KiB
PHP
360 lines
13 KiB
PHP
<?php
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require_once 'HTMLPurifier/Token.php';
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require_once 'HTMLPurifier/Encoder.php';
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require_once 'HTMLPurifier/EntityParser.php';
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// implementations
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require_once 'HTMLPurifier/Lexer/DirectLex.php';
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if (version_compare(PHP_VERSION, "5", ">=")) {
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// You can remove the if statement if you are running PHP 5 only.
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// We ought to get the strict version to follow those rules.
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require_once 'HTMLPurifier/Lexer/DOMLex.php';
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}
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HTMLPurifier_ConfigSchema::define(
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'Core', 'ConvertDocumentToFragment', true, 'bool', '
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This parameter determines whether or not the filter should convert
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input that is a full document with html and body tags to a fragment
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of just the contents of a body tag. This parameter is simply something
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HTML Purifier can do during an edge-case: for most inputs, this
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processing is not necessary.
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');
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HTMLPurifier_ConfigSchema::defineAlias('Core', 'AcceptFullDocuments', 'Core', 'ConvertDocumentToFragment');
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HTMLPurifier_ConfigSchema::define(
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'Core', 'LexerImpl', null, 'mixed/null', '
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<p>
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This parameter determines what lexer implementation can be used. The
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valid values are:
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</p>
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<dl>
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<dt><em>null</em></dt>
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<dd>
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Recommended, the lexer implementation will be auto-detected based on
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your PHP-version and configuration.
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</dd>
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<dt><em>string</em> lexer identifier</dt>
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<dd>
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This is a slim way of manually overridding the implementation.
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Currently recognized values are: DOMLex (the default PHP5 implementation)
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and DirectLex (the default PHP4 implementation). Only use this if
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you know what you are doing: usually, the auto-detection will
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manage things for cases you aren\'t even aware of.
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</dd>
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<dt><em>object</em> lexer instance</dt>
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<dd>
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Super-advanced: you can specify your own, custom, implementation that
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implements the interface defined by <code>HTMLPurifier_Lexer</code>.
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I may remove this option simply because I don\'t expect anyone
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to use it.
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</dd>
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</dl>
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<p>
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This directive has been available since 2.0.0.
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</p>
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'
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);
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HTMLPurifier_ConfigSchema::define(
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'Core', 'MaintainLineNumbers', null, 'bool/null', '
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<p>
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If true, HTML Purifier will add line number information to all tokens.
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This is useful when error reporting is turned on, but can result in
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significant performance degradation and should not be used when
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unnecessary. This directive must be used with the DirectLex lexer,
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as the DOMLex lexer does not (yet) support this functionality.
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If the value is null, an appropriate value will be selected based
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on other configuration. This directive has been available since 2.0.0.
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</p>
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');
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HTMLPurifier_ConfigSchema::define(
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'Core', 'AggressivelyFixLt', false, 'bool', '
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This directive enables aggressive pre-filter fixes HTML Purifier can
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perform in order to ensure that open angled-brackets do not get killed
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during parsing stage. Enabling this will result in two preg_replace_callback
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calls and one preg_replace call for every bit of HTML passed through here.
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It is not necessary and will have no effect for PHP 4.
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This directive has been available since 2.1.0.
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');
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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.
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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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* Be careful when porting this class to PHP 5.
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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 power to create,
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* -# Require recursion to iterate,
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* -# Must be compatible with PHP 5's DOM (otherwise duplication),
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* -# Has the entire document structure (html and body not needed), and
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* -# Has unknown readability improvement.
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*
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* @par
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* What the last item means is that the functions for manipulating tokens are
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* already fairly compact, and when well-commented, more abstraction may not
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* be needed.
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*
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* @see HTMLPurifier_Token
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*/
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class HTMLPurifier_Lexer
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{
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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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* Depending on what PHP version you are running, the abstract base
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* Lexer class will determine which concrete Lexer is best for you:
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* HTMLPurifier_Lexer_DirectLex for PHP 4, and HTMLPurifier_Lexer_DOMLex
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* for PHP 5 and beyond. This general rule has a few exceptions to it
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* involving special features that only DirectLex 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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* @note In PHP4, it is possible to call this factory method from
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* subclasses, such usage is not recommended and not
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* forwards-compatible.
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*
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* @param $prototype Optional prototype lexer or configuration object
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* @return Concrete lexer.
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*/
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public static function create($config) {
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if (!($config instanceof HTMLPurifier_Config)) {
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$lexer = $config;
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trigger_error("Passing a prototype to
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HTMLPurifier_Lexer::create() is deprecated, please instead
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use %Core.LexerImpl", E_USER_WARNING);
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} else {
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$lexer = $config->get('Core', 'LexerImpl');
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}
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if (is_object($lexer)) {
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return $lexer;
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}
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if (is_null($lexer)) { do {
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// auto-detection algorithm
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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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$line_numbers = $config->get('Core', 'MaintainLineNumbers');
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if (
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$line_numbers === true ||
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($line_numbers === null && $config->get('Core', 'CollectErrors'))
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) {
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$lexer = 'DirectLex';
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break;
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}
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if (version_compare(PHP_VERSION, "5", ">=") && // check for PHP5
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class_exists('DOMDocument')) { // check for DOM support
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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); } // do..while so we can break
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// instantiate recognized string names
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switch ($lexer) {
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case 'DOMLex':
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return new HTMLPurifier_Lexer_DOMLex();
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case 'DirectLex':
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return new HTMLPurifier_Lexer_DirectLex();
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case 'PH5P':
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// experimental Lexer that must be manually included
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return new HTMLPurifier_Lexer_PH5P();
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default:
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trigger_error("Cannot instantiate unrecognized Lexer type " . htmlspecialchars($lexer), E_USER_ERROR);
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}
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}
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// -- CONVENIENCE MEMBERS ---------------------------------------------
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public function __construct() {
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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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*/
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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 $string String character data to be parsed.
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* @returns Parsed character data.
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*/
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public function parseData($string) {
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// following functions require at least one character
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if ($string === '') return '';
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// subtracts amps that cannot possibly be escaped
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$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) return $string; // abort if no entities
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$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) return $string;
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// hmm... now we have some uncommon entities. Use the callback.
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$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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*
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* @param $string String HTML.
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* @return HTMLPurifier_Token array representation of HTML.
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*/
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public function tokenizeHTML($string, $config, &$context) {
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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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*
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* @param $string HTML string to process.
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* @returns HTML with CDATA sections escaped.
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*/
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protected static function escapeCDATA($string) {
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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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$string
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);
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}
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/**
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* Special CDATA case that is especially convoluted for <script>
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*/
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protected static function escapeCommentedCDATA($string) {
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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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* 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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* @params $matches PCRE matches array, with index 0 the entire match
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* and 1 the inside of the CDATA section.
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* @returns Escaped internals of the CDATA section.
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*/
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protected static function CDATACallback($matches) {
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// not exactly sure why the character set is needed, but whatever
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return htmlspecialchars($matches[1], ENT_COMPAT, 'UTF-8');
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}
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/**
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* Takes a piece of HTML and normalizes it by converting entities, fixing
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* encoding, extracting bits, and other good stuff.
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* @todo Consider making protected
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*/
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public function normalize($html, $config, &$context) {
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// extract body from document if applicable
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if ($config->get('Core', 'ConvertDocumentToFragment')) {
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$html = $this->extractBody($html);
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}
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// normalize newlines to \n
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$html = str_replace("\r\n", "\n", $html);
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$html = str_replace("\r", "\n", $html);
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if ($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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// 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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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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$matches = array();
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$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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