mirror of
https://github.com/ezyang/htmlpurifier.git
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2fa1161d3d
- Optimized and documented DirectLex. - Rearranged test cases. git-svn-id: http://htmlpurifier.org/svnroot/htmlpurifier/trunk@100 48356398-32a2-884e-a903-53898d9a118a
458 lines
16 KiB
PHP
458 lines
16 KiB
PHP
<?php
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require_once 'HTMLPurifier/Lexer.php';
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/**
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* Our in-house implementation of a parser.
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*
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* A pure PHP parser, DirectLex has absolutely no dependencies, making
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* it a reasonably good default for PHP4. Written with efficiency in mind,
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* it can be four times faster than HTMLPurifier_Lexer_PEARSax3, although it
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* pales in comparison to HTMLPurifier_Lexer_DOMLex. It will support UTF-8
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* completely eventually.
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*
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* @todo Implement non-special string entity conversion.
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* @todo Reread XML spec and document differences.
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* @todo Add support for CDATA sections.
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* @todo Determine correct behavior in outputting comment data. (preserve dashes?)
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* @todo Optimize main function tokenizeHTML().
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*/
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class HTMLPurifier_Lexer_DirectLex extends HTMLPurifier_Lexer
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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 $string String character data to be parsed.
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* @returns Parsed character data.
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*/
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function parseData($string) {
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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 = $this->substituteSpecialEntities($string);
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return $string;
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}
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/**
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* Whitespace characters for str(c)spn.
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* @protected
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*/
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var $_whitespace = "\x20\x09\x0D\x0A";
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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 = array(
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34 => '"', // quote
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38 => '&', // ampersand
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39 => "'", // apostrophe
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60 => '<', // less than sign
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62 => '>' // greater than sign
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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 = 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 = 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 $_substituteEntitiesRegex =
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// 1. hex 2. dec 3. string
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'/&[#](?:x([a-fA-F0-9]+)|0*(\d+)|([A-Za-z]+));?/';
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/**
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* Substitutes non-special entities with their parsed equivalents.
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*/
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function substituteNonSpecialEntities($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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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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// translate $matches[3]
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}
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}
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/**
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* Substitutes only special entities with their parsed equivalents.
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*
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* We try to avoid calling this function because otherwise, it would have
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* to be called a lot (for every parsed section).
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*/
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function substituteSpecialEntities($string) {
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return preg_replace_callback(
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$this->_substituteEntitiesRegex,
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array('HTMLPurifier_Lexer_DirectLex', 'specialEntityCallback'),
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$string);
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}
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/**
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* Callback function for substituteSpecialEntities() that does the work.
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*
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* This callback is very similar to nonSpecialEntityCallback().
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*/
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function specialEntityCallback($matches) {
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$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) $matches[2];
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return isset($this->_special_dec2str[$int]) ?
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$this->_special_dec2str[$int] :
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$entity;
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} else {
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return isset($this->_special_ent2dec[$matches[3]]) ?
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$this->_special_ent2dec[$matches[3]] :
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$entity;
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}
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}
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function tokenizeHTML($string) {
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// some quick checking (if empty, return empty)
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$string = @ (string) $string;
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if ($string == '') return array();
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$cursor = 0; // our location in the text
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$inside_tag = false; // whether or not we're parsing the inside of a tag
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$array = array(); // result array
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// expand entities THAT AREN'T THE BIG FIVE
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$string = $this->substituteNonSpecialEntities($string);
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// infinite loop protection
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// has to be pretty big, since html docs can be big
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// we're allow two hundred thousand tags... more than enough?
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$loops = 0;
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while(true) {
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// infinite loop protection
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if (++$loops > 200000) return array();
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$position_next_lt = strpos($string, '<', $cursor);
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$position_next_gt = strpos($string, '>', $cursor);
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// triggers on "<b>asdf</b>" but not "asdf <b></b>"
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if ($position_next_lt === $cursor) {
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$inside_tag = true;
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$cursor++;
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}
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if (!$inside_tag && $position_next_lt !== false) {
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// We are not inside tag and there still is another tag to parse
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$array[] = new
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HTMLPurifier_Token_Text(
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$this->parseData(
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substr(
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$string, $cursor, $position_next_lt - $cursor
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)
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)
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);
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$cursor = $position_next_lt + 1;
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$inside_tag = true;
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continue;
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} elseif (!$inside_tag) {
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// We are not inside tag but there are no more tags
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// If we're already at the end, break
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if ($cursor === strlen($string)) break;
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// Create Text of rest of string
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$array[] = new
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HTMLPurifier_Token_Text(
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$this->parseData(
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substr(
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$string, $cursor
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)
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)
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);
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break;
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} elseif ($inside_tag && $position_next_gt !== false) {
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// We are in tag and it is well formed
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// Grab the internals of the tag
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$strlen_segment = $position_next_gt - $cursor;
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$segment = substr($string, $cursor, $strlen_segment);
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// Check if it's a comment
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if (
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substr($segment, 0, 3) == '!--' &&
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substr($segment, $strlen_segment-2, 2) == '--'
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) {
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$array[] = new
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HTMLPurifier_Token_Comment(
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substr(
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$segment, 3, $strlen_segment - 5
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)
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);
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$inside_tag = false;
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$cursor = $position_next_gt + 1;
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continue;
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}
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// Check if it's an end tag
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$is_end_tag = (strpos($segment,'/') === 0);
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if ($is_end_tag) {
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$type = substr($segment, 1);
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$array[] = new HTMLPurifier_Token_End($type);
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$inside_tag = false;
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$cursor = $position_next_gt + 1;
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continue;
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}
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// Check if it is explicitly self closing, if so, remove
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// trailing slash. Remember, we could have a tag like <br>, so
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// any later token processing scripts must convert improperly
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// classified EmptyTags from StartTags.
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$is_self_closing= (strpos($segment,'/') === $strlen_segment-1);
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if ($is_self_closing) {
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$strlen_segment--;
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$segment = substr($segment, 0, $strlen_segment);
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}
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// Check if there are any attributes
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$position_first_space = strcspn($segment, $this->_whitespace);
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if ($position_first_space >= $strlen_segment) {
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if ($is_self_closing) {
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$array[] = new HTMLPurifier_Token_Empty($segment);
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} else {
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$array[] = new HTMLPurifier_Token_Start($segment);
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}
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$inside_tag = false;
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$cursor = $position_next_gt + 1;
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continue;
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}
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// Grab out all the data
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$type = substr($segment, 0, $position_first_space);
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$attribute_string =
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trim(
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substr(
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$segment, $position_first_space
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)
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);
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if ($attribute_string) {
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$attributes = $this->parseAttributeString(
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$attribute_string
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);
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} else {
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$attributes = array();
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}
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if ($is_self_closing) {
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$array[] = new HTMLPurifier_Token_Empty($type, $attributes);
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} else {
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$array[] = new HTMLPurifier_Token_Start($type, $attributes);
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}
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$cursor = $position_next_gt + 1;
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$inside_tag = false;
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continue;
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} else {
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$array[] = new
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HTMLPurifier_Token_Text(
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'<' .
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$this->parseData(
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substr($string, $cursor)
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)
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);
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break;
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}
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break;
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}
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return $array;
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}
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/**
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* Takes the inside of an HTML tag and makes an assoc array of attributes.
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*
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* @param $string Inside of tag excluding name.
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* @return Assoc array of attributes.
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*/
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function parseAttributeString($string) {
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$string = (string) $string; // quick typecast
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if ($string == '') return array(); // no attributes
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// let's see if we can abort as quickly as possible
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// one equal sign, no spaces => one attribute
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$num_equal = substr_count($string, '=');
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$has_space = strpos($string, ' ');
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if ($num_equal === 0 && !$has_space) {
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// bool attribute
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return array($string => $string);
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} elseif ($num_equal === 1 && !$has_space) {
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// only one attribute
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list($key, $quoted_value) = explode('=', $string);
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$quoted_value = trim($quoted_value);
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if (!$key) return array();
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if (!$quoted_value) return array($key => '');
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$first_char = @$quoted_value[0];
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$last_char = @$quoted_value[strlen($quoted_value)-1];
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$same_quote = ($first_char == $last_char);
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$open_quote = ($first_char == '"' || $first_char == "'");
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if ( $same_quote && $open_quote) {
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// well behaved
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$value = substr($quoted_value, 1, strlen($quoted_value) - 2);
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} else {
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// not well behaved
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if ($open_quote) {
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$value = substr($quoted_value, 1);
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} else {
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$value = $quoted_value;
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}
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}
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return array($key => $value);
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}
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// setup loop environment
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$array = array(); // return assoc array of attributes
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$cursor = 0; // current position in string (moves forward)
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$size = strlen($string); // size of the string (stays the same)
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// if we have unquoted attributes, the parser expects a terminating
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// space, so let's guarantee that there's always a terminating space.
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$string .= ' ';
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// infinite loop protection
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$loops = 0;
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while(true) {
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// infinite loop protection
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if (++$loops > 1000) return array();
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if ($cursor >= $size) {
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break;
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}
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$cursor += ($value = strspn($string, $this->_whitespace, $cursor));
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// grab the key
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$key_begin = $cursor; //we're currently at the start of the key
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// scroll past all characters that are the key (not whitespace or =)
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$cursor += strcspn($string, $this->_whitespace . '=', $cursor);
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$key_end = $cursor; // now at the end of the key
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$key = substr($string, $key_begin, $key_end - $key_begin);
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if (!$key) continue; // empty key
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// scroll past all whitespace
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$cursor += strspn($string, $this->_whitespace, $cursor);
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if ($cursor >= $size) {
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$array[$key] = $key;
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break;
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}
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// if the next character is an equal sign, we've got a regular
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// pair, otherwise, it's a bool attribute
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$first_char = @$string[$cursor];
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if ($first_char == '=') {
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// key="value"
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$cursor++;
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$cursor += strspn($string, $this->_whitespace, $cursor);
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// we might be in front of a quote right now
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$char = @$string[$cursor];
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if ($char == '"' || $char == "'") {
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// it's quoted, end bound is $char
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$cursor++;
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$value_begin = $cursor;
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$cursor = strpos($string, $char, $cursor);
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$value_end = $cursor;
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} else {
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// it's not quoted, end bound is whitespace
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$value_begin = $cursor;
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$cursor += strcspn($string, $this->_whitespace, $cursor);
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$value_end = $cursor;
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}
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$value = substr($string, $value_begin, $value_end - $value_begin);
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$array[$key] = $this->parseData($value);
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$cursor++;
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} else {
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// boolattr
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if ($key !== '') {
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$array[$key] = $key;
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}
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}
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}
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return $array;
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}
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}
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?>
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