mirror of
https://github.com/ezyang/htmlpurifier.git
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7588068b7b
git-svn-id: http://htmlpurifier.org/svnroot/htmlpurifier/trunk@328 48356398-32a2-884e-a903-53898d9a118a
474 lines
18 KiB
PHP
474 lines
18 KiB
PHP
<?php
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require_once 'HTMLPurifier/Token.php';
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HTMLPurifier_ConfigDef::define(
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'Core', 'AcceptFullDocuments', true, 'bool',
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'This parameter determines whether or not the filter should accept full '.
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'HTML documents, not just HTML fragments. When on, it will '.
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'drop all sections except the content between body. Depending on '.
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'the implementation in use, this may speed up document parse times.'
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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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/**
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* Lexes an HTML string into tokens.
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*
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* @param $string String HTML.
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* @return HTMLPurifier_Token array representation of HTML.
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*/
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function tokenizeHTML($string, $config = null) {
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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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* 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.
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*
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* Passing the optional prototype lexer parameter will override the
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* default with your own implementation. A copy/reference of the prototype
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* lexer will now be returned when you request a new lexer.
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*
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* @note
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* Though it is possible to call this factory method from subclasses,
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* such usage is not recommended.
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*
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* @param $prototype Optional prototype lexer.
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* @return Concrete lexer.
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*/
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function create($prototype = null) {
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// we don't really care if it's a reference or a copy
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static $lexer = null;
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if ($prototype) {
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$lexer = $prototype;
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}
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if (empty($lexer)) {
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if (version_compare(PHP_VERSION, '5', '>=')) {
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require_once 'HTMLPurifier/Lexer/DOMLex.php';
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$lexer = new HTMLPurifier_Lexer_DOMLex();
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} else {
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require_once 'HTMLPurifier/Lexer/DirectLex.php';
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$lexer = new HTMLPurifier_Lexer_DirectLex();
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}
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}
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return $lexer;
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}
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/**
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* Decimal to parsed string conversion table for special entities.
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* @protected
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*/
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var $_special_dec2str =
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array(
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34 => '"',
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38 => '&',
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39 => "'",
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60 => '<',
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62 => '>'
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);
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/**
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* Stripped entity names to decimal conversion table for special entities.
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* @protected
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*/
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var $_special_ent2dec =
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array(
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'quot' => 34,
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'amp' => 38,
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'lt' => 60,
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'gt' => 62
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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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* @protected
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*/
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var $_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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* Callback regex string for parsing entities.
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* @protected
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*/
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var $_substituteEntitiesRegex =
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'/&(?:[#]x([a-fA-F0-9]+)|[#]0*(\d+)|([A-Za-z]+));?/';
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// 1. hex 2. dec 3. string
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/**
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* Substitutes non-special entities with their parsed equivalents. Since
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* running this whenever you have parsed character is t3h 5uck, we run
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* it before everything else.
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*
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* @protected
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* @param $string String to have non-special entities parsed.
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* @returns Parsed string.
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*/
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function substituteNonSpecialEntities($string) {
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// it will try to detect missing semicolons, but don't rely on it
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return preg_replace_callback(
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$this->_substituteEntitiesRegex,
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array($this, 'nonSpecialEntityCallback'),
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$string
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);
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}
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/**
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* Callback function for substituteNonSpecialEntities() 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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* @note Based on Feyd's function at
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* <http://forums.devnetwork.net/viewtopic.php?p=191404#191404>,
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* which is in public domain.
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* @note While we're going to do code point parsing anyway, a good
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* optimization would be to refuse to translate code points that
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* are non-SGML characters. However, this could lead to duplication.
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* @param $matches PCRE matches array, with 0 the entire match, and
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* either index 1, 2 or 3 set with a hex value, dec value,
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* or string (respectively).
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* @returns Replacement string.
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* @todo Implement string translations
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*/
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// +----------+----------+----------+----------+
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// | 33222222 | 22221111 | 111111 | |
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// | 10987654 | 32109876 | 54321098 | 76543210 | bit
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// +----------+----------+----------+----------+
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// | | | | 0xxxxxxx | 1 byte 0x00000000..0x0000007F
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// | | | 110yyyyy | 10xxxxxx | 2 byte 0x00000080..0x000007FF
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// | | 1110zzzz | 10yyyyyy | 10xxxxxx | 3 byte 0x00000800..0x0000FFFF
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// | 11110www | 10wwzzzz | 10yyyyyy | 10xxxxxx | 4 byte 0x00010000..0x0010FFFF
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// +----------+----------+----------+----------+
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// | 00000000 | 00011111 | 11111111 | 11111111 | Theoretical upper limit of legal scalars: 2097151 (0x001FFFFF)
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// | 00000000 | 00010000 | 11111111 | 11111111 | Defined upper limit of legal scalar codes
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// +----------+----------+----------+----------+
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function nonSpecialEntityCallback($matches) {
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// replaces all but big five
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$entity = $matches[0];
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$is_num = (@$matches[0][1] === '#');
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if ($is_num) {
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$is_hex = (@$entity[2] === 'x');
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$code = $is_hex ? hexdec($matches[1]) : (int) $matches[2];
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// abort for special characters
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if (isset($this->_special_dec2str[$code])) return $entity;
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if($code > 1114111 or $code < 0 or
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($code >= 55296 and $code <= 57343) ) {
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// bits are set outside the "valid" range as defined
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// by UNICODE 4.1.0
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return '';
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}
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$x = $y = $z = $w = 0;
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if ($code < 128) {
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// regular ASCII character
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$x = $code;
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} else {
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// set up bits for UTF-8
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$x = ($code & 63) | 128;
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if ($code < 2048) {
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$y = (($code & 2047) >> 6) | 192;
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} else {
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$y = (($code & 4032) >> 6) | 128;
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if($code < 65536) {
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$z = (($code >> 12) & 15) | 224;
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} else {
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$z = (($code >> 12) & 63) | 128;
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$w = (($code >> 18) & 7) | 240;
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}
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}
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}
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// set up the actual character
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$ret = '';
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if($w) $ret .= chr($w);
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if($z) $ret .= chr($z);
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if($y) $ret .= chr($y);
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$ret .= chr($x);
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return $ret;
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} else {
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if (isset($this->_special_ent2dec[$matches[3]])) return $entity;
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if (!$this->_entity_lookup) {
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require_once 'HTMLPurifier/EntityLookup.php';
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$this->_entity_lookup = HTMLPurifier_EntityLookup::instance();
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}
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if (isset($this->_entity_lookup->table[$matches[3]])) {
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return $this->_entity_lookup->table[$matches[3]];
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} else {
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return $entity;
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}
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}
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}
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/**
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* Contains a copy of the EntityLookup table.
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* @protected
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*/
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var $_entity_lookup;
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/**
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* Translates CDATA sections into regular sections (through escaping).
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*
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* @protected
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* @param $string HTML string to process.
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* @returns HTML with CDATA sections escaped.
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*/
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function escapeCDATA($string) {
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return preg_replace_callback(
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'/<!\[CDATA\[(.+?)\]\]>/',
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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 $matches PCRE matches array, with index 0 the entire match
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* and 1 the inside of the CDATA section.
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* @returns Escaped internals of the CDATA section.
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*/
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function CDATACallback($matches) {
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// not exactly sure why the character set is needed, but whatever
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return htmlspecialchars($matches[1], ENT_COMPAT, 'UTF-8');
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}
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/**
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* Takes a string of HTML (fragment or document) and returns the content
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*/
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function extractBody($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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* Cleans a UTF-8 string for well-formedness and SGML validity
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*
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* It will parse according to UTF-8 and return a valid UTF8 string, with
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* non-SGML codepoints excluded.
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*
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* @warning This function can find a lot of use, so we may be moving
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* it to a dedicated class.
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*
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* @note Just for reference, the non-SGML code points are 0 to 31 and
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* 127 to 159, inclusive. However, we allow code points 9, 10
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* and 13, which are the tab, line feed and carriage return
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* respectively. 128 and above the code points map to multibyte
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* UTF-8 representations.
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*
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* @note The functionality provided by the original function could be
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* implemented with iconv using 'UTF-8//IGNORE', mbstring, or
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* even the PCRE modifier 'u', these do not allow us to strip
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* control characters or disallowed code points, and the latter
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* does not allow invalid UTF8 characters to be ignored.
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*
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* @note Decomposing the string into Unicode code points is necessary
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* because SGML disallows the use of specific code points, not
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* necessarily bytes. A naive implementation that simply strtr
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* disallowed code points as bytes will break other Unicode
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* characters in which using such bytes is valid.
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*
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* @note Code adapted from utf8ToUnicode by Henri Sivonen and
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* hsivonen@iki.fi at <http://iki.fi/hsivonen/php-utf8/> under the
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* LGPL license. Notes on what changed are inside.
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*/
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function cleanUTF8($str) {
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$mState = 0; // cached expected number of octets after the current octet
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// until the beginning of the next UTF8 character sequence
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$mUcs4 = 0; // cached Unicode character
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$mBytes = 1; // cached expected number of octets in the current sequence
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// original code involved an $out that was an array of Unicode
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// codepoints. Instead of having to convert back into UTF-8, we've
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// decided to directly append valid UTF-8 characters onto a string
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// $out once they're done. $char accumulates raw bytes, while $mUcs4
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// turns into the Unicode code point, so there's some redundancy.
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$out = '';
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$char = '';
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$len = strlen($str);
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for($i = 0; $i < $len; $i++) {
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$in = ord($str{$i});
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$char .= $str[$i]; // append byte to char
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if (0 == $mState) {
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// When mState is zero we expect either a US-ASCII character
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// or a multi-octet sequence.
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if (0 == (0x80 & ($in))) {
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// US-ASCII, pass straight through.
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if (($in <= 31 || $in == 127) &&
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!($in == 9 || $in == 13 || $in == 10) // save \r\t\n
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) {
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// control characters, remove
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} else {
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$out .= $char;
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}
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// reset
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$char = '';
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$mBytes = 1;
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} elseif (0xC0 == (0xE0 & ($in))) {
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// First octet of 2 octet sequence
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$mUcs4 = ($in);
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$mUcs4 = ($mUcs4 & 0x1F) << 6;
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$mState = 1;
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$mBytes = 2;
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} elseif (0xE0 == (0xF0 & ($in))) {
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// First octet of 3 octet sequence
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$mUcs4 = ($in);
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$mUcs4 = ($mUcs4 & 0x0F) << 12;
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$mState = 2;
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$mBytes = 3;
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} elseif (0xF0 == (0xF8 & ($in))) {
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// First octet of 4 octet sequence
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$mUcs4 = ($in);
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$mUcs4 = ($mUcs4 & 0x07) << 18;
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$mState = 3;
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$mBytes = 4;
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} elseif (0xF8 == (0xFC & ($in))) {
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// First octet of 5 octet sequence.
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//
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// This is illegal because the encoded codepoint must be
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// either:
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// (a) not the shortest form or
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// (b) outside the Unicode range of 0-0x10FFFF.
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// Rather than trying to resynchronize, we will carry on
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// until the end of the sequence and let the later error
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// handling code catch it.
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$mUcs4 = ($in);
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$mUcs4 = ($mUcs4 & 0x03) << 24;
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$mState = 4;
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$mBytes = 5;
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} elseif (0xFC == (0xFE & ($in))) {
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// First octet of 6 octet sequence, see comments for 5
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// octet sequence.
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$mUcs4 = ($in);
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$mUcs4 = ($mUcs4 & 1) << 30;
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$mState = 5;
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$mBytes = 6;
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} else {
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// Current octet is neither in the US-ASCII range nor a
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// legal first octet of a multi-octet sequence.
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$mState = 0;
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$mUcs4 = 0;
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$mBytes = 1;
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$char = '';
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}
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} else {
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// When mState is non-zero, we expect a continuation of the
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// multi-octet sequence
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if (0x80 == (0xC0 & ($in))) {
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// Legal continuation.
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$shift = ($mState - 1) * 6;
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$tmp = $in;
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$tmp = ($tmp & 0x0000003F) << $shift;
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$mUcs4 |= $tmp;
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if (0 == --$mState) {
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// End of the multi-octet sequence. mUcs4 now contains
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// the final Unicode codepoint to be output
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// Check for illegal sequences and codepoints.
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// From Unicode 3.1, non-shortest form is illegal
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if (((2 == $mBytes) && ($mUcs4 < 0x0080)) ||
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((3 == $mBytes) && ($mUcs4 < 0x0800)) ||
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((4 == $mBytes) && ($mUcs4 < 0x10000)) ||
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(4 < $mBytes) ||
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// From Unicode 3.2, surrogate characters = illegal
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(($mUcs4 & 0xFFFFF800) == 0xD800) ||
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// Codepoints outside the Unicode range are illegal
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($mUcs4 > 0x10FFFF)
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) {
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} elseif (0xFEFF != $mUcs4 && // omit BOM
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!($mUcs4 >= 128 && $mUcs4 <= 159) // omit non-SGML
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) {
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$out .= $char;
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}
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// initialize UTF8 cache (reset)
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$mState = 0;
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$mUcs4 = 0;
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$mBytes = 1;
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$char = '';
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}
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} else {
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// ((0xC0 & (*in) != 0x80) && (mState != 0))
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// Incomplete multi-octet sequence.
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// used to result in complete fail, but we'll reset
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$mState = 0;
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$mUcs4 = 0;
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$mBytes = 1;
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$char ='';
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}
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}
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}
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return $out;
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}
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}
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?>
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