mirror of https://github.com/friendica/friendica
293 lines
9.8 KiB
PHP
293 lines
9.8 KiB
PHP
<?php
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/*! @mainpage
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*
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* HTML Purifier is an HTML filter that will take an arbitrary snippet of
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* HTML and rigorously test, validate and filter it into a version that
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* is safe for output onto webpages. It achieves this by:
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*
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* -# Lexing (parsing into tokens) the document,
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* -# Executing various strategies on the tokens:
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* -# Removing all elements not in the whitelist,
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* -# Making the tokens well-formed,
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* -# Fixing the nesting of the nodes, and
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* -# Validating attributes of the nodes; and
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* -# Generating HTML from the purified tokens.
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*
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* However, most users will only need to interface with the HTMLPurifier
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* and HTMLPurifier_Config.
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*/
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/*
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HTML Purifier 4.7.0 - Standards Compliant HTML Filtering
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Copyright (C) 2006-2008 Edward Z. Yang
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This library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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This library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with this library; if not, write to the Free Software
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Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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/**
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* Facade that coordinates HTML Purifier's subsystems in order to purify HTML.
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*
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* @note There are several points in which configuration can be specified
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* for HTML Purifier. The precedence of these (from lowest to
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* highest) is as follows:
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* -# Instance: new HTMLPurifier($config)
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* -# Invocation: purify($html, $config)
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* These configurations are entirely independent of each other and
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* are *not* merged (this behavior may change in the future).
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*
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* @todo We need an easier way to inject strategies using the configuration
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* object.
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*/
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class HTMLPurifier
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{
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/**
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* Version of HTML Purifier.
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* @type string
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*/
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public $version = '4.7.0';
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/**
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* Constant with version of HTML Purifier.
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*/
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const VERSION = '4.7.0';
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/**
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* Global configuration object.
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* @type HTMLPurifier_Config
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*/
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public $config;
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/**
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* Array of extra filter objects to run on HTML,
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* for backwards compatibility.
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* @type HTMLPurifier_Filter[]
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*/
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private $filters = array();
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/**
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* Single instance of HTML Purifier.
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* @type HTMLPurifier
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*/
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private static $instance;
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/**
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* @type HTMLPurifier_Strategy_Core
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*/
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protected $strategy;
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/**
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* @type HTMLPurifier_Generator
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*/
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protected $generator;
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/**
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* Resultant context of last run purification.
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* Is an array of contexts if the last called method was purifyArray().
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* @type HTMLPurifier_Context
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*/
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public $context;
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/**
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* Initializes the purifier.
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*
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* @param HTMLPurifier_Config $config Optional HTMLPurifier_Config object
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* for all instances of the purifier, if omitted, a default
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* configuration is supplied (which can be overridden on a
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* per-use basis).
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* The parameter can also be any type that
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* HTMLPurifier_Config::create() supports.
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*/
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public function __construct($config = null)
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{
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$this->config = HTMLPurifier_Config::create($config);
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$this->strategy = new HTMLPurifier_Strategy_Core();
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}
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/**
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* Adds a filter to process the output. First come first serve
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*
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* @param HTMLPurifier_Filter $filter HTMLPurifier_Filter object
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*/
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public function addFilter($filter)
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{
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trigger_error(
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'HTMLPurifier->addFilter() is deprecated, use configuration directives' .
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' in the Filter namespace or Filter.Custom',
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E_USER_WARNING
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);
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$this->filters[] = $filter;
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}
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/**
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* Filters an HTML snippet/document to be XSS-free and standards-compliant.
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*
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* @param string $html String of HTML to purify
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* @param HTMLPurifier_Config $config Config object for this operation,
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* if omitted, defaults to the config object specified during this
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* object's construction. The parameter can also be any type
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* that HTMLPurifier_Config::create() supports.
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*
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* @return string Purified HTML
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*/
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public function purify($html, $config = null)
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{
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// :TODO: make the config merge in, instead of replace
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$config = $config ? HTMLPurifier_Config::create($config) : $this->config;
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// implementation is partially environment dependant, partially
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// configuration dependant
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$lexer = HTMLPurifier_Lexer::create($config);
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$context = new HTMLPurifier_Context();
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// setup HTML generator
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$this->generator = new HTMLPurifier_Generator($config, $context);
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$context->register('Generator', $this->generator);
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// set up global context variables
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if ($config->get('Core.CollectErrors')) {
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// may get moved out if other facilities use it
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$language_factory = HTMLPurifier_LanguageFactory::instance();
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$language = $language_factory->create($config, $context);
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$context->register('Locale', $language);
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$error_collector = new HTMLPurifier_ErrorCollector($context);
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$context->register('ErrorCollector', $error_collector);
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}
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// setup id_accumulator context, necessary due to the fact that
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// AttrValidator can be called from many places
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$id_accumulator = HTMLPurifier_IDAccumulator::build($config, $context);
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$context->register('IDAccumulator', $id_accumulator);
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$html = HTMLPurifier_Encoder::convertToUTF8($html, $config, $context);
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// setup filters
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$filter_flags = $config->getBatch('Filter');
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$custom_filters = $filter_flags['Custom'];
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unset($filter_flags['Custom']);
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$filters = array();
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foreach ($filter_flags as $filter => $flag) {
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if (!$flag) {
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continue;
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}
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if (strpos($filter, '.') !== false) {
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continue;
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}
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$class = "HTMLPurifier_Filter_$filter";
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$filters[] = new $class;
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}
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foreach ($custom_filters as $filter) {
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// maybe "HTMLPurifier_Filter_$filter", but be consistent with AutoFormat
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$filters[] = $filter;
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}
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$filters = array_merge($filters, $this->filters);
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// maybe prepare(), but later
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for ($i = 0, $filter_size = count($filters); $i < $filter_size; $i++) {
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$html = $filters[$i]->preFilter($html, $config, $context);
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}
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// purified HTML
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$html =
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$this->generator->generateFromTokens(
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// list of tokens
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$this->strategy->execute(
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// list of un-purified tokens
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$lexer->tokenizeHTML(
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// un-purified HTML
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$html,
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$config,
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$context
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),
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$config,
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$context
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)
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);
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for ($i = $filter_size - 1; $i >= 0; $i--) {
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$html = $filters[$i]->postFilter($html, $config, $context);
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}
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$html = HTMLPurifier_Encoder::convertFromUTF8($html, $config, $context);
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$this->context =& $context;
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return $html;
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}
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/**
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* Filters an array of HTML snippets
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*
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* @param string[] $array_of_html Array of html snippets
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* @param HTMLPurifier_Config $config Optional config object for this operation.
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* See HTMLPurifier::purify() for more details.
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*
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* @return string[] Array of purified HTML
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*/
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public function purifyArray($array_of_html, $config = null)
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{
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$context_array = array();
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foreach ($array_of_html as $key => $html) {
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$array_of_html[$key] = $this->purify($html, $config);
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$context_array[$key] = $this->context;
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}
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$this->context = $context_array;
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return $array_of_html;
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}
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/**
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* Singleton for enforcing just one HTML Purifier in your system
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*
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* @param HTMLPurifier|HTMLPurifier_Config $prototype Optional prototype
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* HTMLPurifier instance to overload singleton with,
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* or HTMLPurifier_Config instance to configure the
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* generated version with.
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*
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* @return HTMLPurifier
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*/
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public static function instance($prototype = null)
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{
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if (!self::$instance || $prototype) {
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if ($prototype instanceof HTMLPurifier) {
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self::$instance = $prototype;
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} elseif ($prototype) {
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self::$instance = new HTMLPurifier($prototype);
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} else {
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self::$instance = new HTMLPurifier();
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}
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}
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return self::$instance;
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}
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/**
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* Singleton for enforcing just one HTML Purifier in your system
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*
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* @param HTMLPurifier|HTMLPurifier_Config $prototype Optional prototype
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* HTMLPurifier instance to overload singleton with,
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* or HTMLPurifier_Config instance to configure the
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* generated version with.
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*
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* @return HTMLPurifier
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* @note Backwards compatibility, see instance()
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*/
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public static function getInstance($prototype = null)
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{
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return HTMLPurifier::instance($prototype);
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}
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}
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// vim: et sw=4 sts=4
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