mirror of
https://github.com/ezyang/htmlpurifier.git
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5ce0ae7056
git-svn-id: http://htmlpurifier.org/svnroot/htmlpurifier/trunk@105 48356398-32a2-884e-a903-53898d9a118a
152 lines
5.2 KiB
PHP
152 lines
5.2 KiB
PHP
<?php
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require_once 'HTMLPurifier/Token.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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* The 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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* The 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 cannot be directly instantiated, but you may use create() to
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* retrieve a default copy of the lexer.
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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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* @note
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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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* @note
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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) {
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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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* 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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// 1. hex 2. dec 3. string
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'/&[#](?:x([a-fA-F0-9]+)|0*(\d+)|([A-Za-z]+));?/';
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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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$this->_substituteEntitiesRegex,
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array('HTMLPurifier_Lexer_DirectLex', 'nonSpecialEntityCallback'),
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$string);
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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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* @param $matches PCRE-style matches array, with 0 the entire match, and
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* either index 1, 2 or 3 set with a hex value, dec value,
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* or string (respectively).
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* @returns Replacement string.
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* @todo Implement string translations
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*/
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function nonSpecialEntityCallback($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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$int = $is_hex ? hexdec($matches[1]) : (int) $matches[2];
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if (isset($this->_special_dec2str[$int])) return $entity;
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return chr($int);
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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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$this->_entity_lookup = EntityLookup::instance();
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}
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if (isset($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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var $_entity_lookup;
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}
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?>
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