449 lines
9.9 KiB
PHP
449 lines
9.9 KiB
PHP
<?php
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/**
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* @package Joomla.Platform
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* @subpackage Language
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*
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* @copyright Copyright (C) 2005 - 2013 Open Source Matters, Inc. All rights reserved.
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* @copyright Copyright (C) 2005 Richard Heyes (http://www.phpguru.org/). All rights reserved.
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* @license GNU General Public License version 2 or later; see LICENSE
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*/
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defined('JPATH_PLATFORM') or die;
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/**
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* Porter English stemmer class.
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*
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* This class was adapted from one written by Richard Heyes.
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* See copyright and link information above.
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*
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* @package Joomla.Platform
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* @subpackage Language
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* @since 12.1
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*/
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class JLanguageStemmerPorteren extends JLanguageStemmer
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{
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/**
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* Regex for matching a consonant.
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*
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* @var string
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* @since 12.1
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*/
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private static $_regex_consonant = '(?:[bcdfghjklmnpqrstvwxz]|(?<=[aeiou])y|^y)';
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/**
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* Regex for matching a vowel
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* @var string
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* @since 12.1
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*/
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private static $_regex_vowel = '(?:[aeiou]|(?<![aeiou])y)';
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/**
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* Method to stem a token and return the root.
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*
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* @param string $token The token to stem.
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* @param string $lang The language of the token.
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*
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* @return string The root token.
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*
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* @since 12.1
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*/
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public function stem($token, $lang)
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{
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// Check if the token is long enough to merit stemming.
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if (strlen($token) <= 2)
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{
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return $token;
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}
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// Check if the language is English or All.
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if ($lang !== 'en')
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{
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return $token;
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}
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// Stem the token if it is not in the cache.
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if (!isset($this->cache[$lang][$token]))
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{
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// Stem the token.
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$result = $token;
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$result = self::_step1ab($result);
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$result = self::_step1c($result);
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$result = self::_step2($result);
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$result = self::_step3($result);
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$result = self::_step4($result);
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$result = self::_step5($result);
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// Add the token to the cache.
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$this->cache[$lang][$token] = $result;
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}
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return $this->cache[$lang][$token];
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}
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/**
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* Step 1
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*
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* @param string $word The token to stem.
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*
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* @return string
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*
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* @since 12.1
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*/
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private static function _step1ab($word)
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{
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// Part a
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if (substr($word, -1) == 's')
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{
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self::_replace($word, 'sses', 'ss')
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or self::_replace($word, 'ies', 'i')
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or self::_replace($word, 'ss', 'ss')
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or self::_replace($word, 's', '');
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}
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// Part b
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if (substr($word, -2, 1) != 'e' or !self::_replace($word, 'eed', 'ee', 0))
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{
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// First rule
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$v = self::$_regex_vowel;
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// Check ing and ed
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// Note use of && and OR, for precedence reasons
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if (preg_match("#$v+#", substr($word, 0, -3)) && self::_replace($word, 'ing', '')
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or preg_match("#$v+#", substr($word, 0, -2)) && self::_replace($word, 'ed', ''))
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{
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// If one of above two test successful
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if (!self::_replace($word, 'at', 'ate') and !self::_replace($word, 'bl', 'ble') and !self::_replace($word, 'iz', 'ize'))
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{
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// Double consonant ending
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if (self::_doubleConsonant($word) and substr($word, -2) != 'll' and substr($word, -2) != 'ss' and substr($word, -2) != 'zz')
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{
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$word = substr($word, 0, -1);
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}
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elseif (self::_m($word) == 1 and self::_cvc($word))
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{
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$word .= 'e';
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}
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}
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}
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}
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return $word;
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}
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/**
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* Step 1c
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*
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* @param string $word The token to stem.
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*
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* @return string
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*
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* @since 12.1
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*/
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private static function _step1c($word)
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{
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$v = self::$_regex_vowel;
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if (substr($word, -1) == 'y' && preg_match("#$v+#", substr($word, 0, -1)))
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{
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self::_replace($word, 'y', 'i');
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}
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return $word;
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}
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/**
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* Step 2
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*
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* @param string $word The token to stem.
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*
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* @return string
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*
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* @since 12.1
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*/
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private static function _step2($word)
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{
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switch (substr($word, -2, 1))
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{
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case 'a':
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self::_replace($word, 'ational', 'ate', 0)
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or self::_replace($word, 'tional', 'tion', 0);
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break;
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case 'c':
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self::_replace($word, 'enci', 'ence', 0)
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or self::_replace($word, 'anci', 'ance', 0);
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break;
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case 'e':
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self::_replace($word, 'izer', 'ize', 0);
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break;
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case 'g':
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self::_replace($word, 'logi', 'log', 0);
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break;
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case 'l':
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self::_replace($word, 'entli', 'ent', 0)
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or self::_replace($word, 'ousli', 'ous', 0)
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or self::_replace($word, 'alli', 'al', 0)
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or self::_replace($word, 'bli', 'ble', 0)
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or self::_replace($word, 'eli', 'e', 0);
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break;
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case 'o':
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self::_replace($word, 'ization', 'ize', 0)
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or self::_replace($word, 'ation', 'ate', 0)
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or self::_replace($word, 'ator', 'ate', 0);
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break;
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case 's':
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self::_replace($word, 'iveness', 'ive', 0)
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or self::_replace($word, 'fulness', 'ful', 0)
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or self::_replace($word, 'ousness', 'ous', 0)
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or self::_replace($word, 'alism', 'al', 0);
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break;
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case 't':
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self::_replace($word, 'biliti', 'ble', 0)
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or self::_replace($word, 'aliti', 'al', 0)
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or self::_replace($word, 'iviti', 'ive', 0);
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break;
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}
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return $word;
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}
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/**
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* Step 3
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*
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* @param string $word The token to stem.
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*
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* @return string
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*
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* @since 12.1
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*/
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private static function _step3($word)
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{
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switch (substr($word, -2, 1))
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{
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case 'a':
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self::_replace($word, 'ical', 'ic', 0);
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break;
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case 's':
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self::_replace($word, 'ness', '', 0);
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break;
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case 't':
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self::_replace($word, 'icate', 'ic', 0)
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or self::_replace($word, 'iciti', 'ic', 0);
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break;
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case 'u':
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self::_replace($word, 'ful', '', 0);
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break;
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case 'v':
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self::_replace($word, 'ative', '', 0);
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break;
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case 'z':
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self::_replace($word, 'alize', 'al', 0);
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break;
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}
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return $word;
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}
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/**
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* Step 4
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*
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* @param string $word The token to stem.
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*
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* @return string
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*
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* @since 12.1
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*/
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private static function _step4($word)
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{
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switch (substr($word, -2, 1))
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{
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case 'a':
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self::_replace($word, 'al', '', 1);
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break;
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case 'c':
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self::_replace($word, 'ance', '', 1)
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or self::_replace($word, 'ence', '', 1);
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break;
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case 'e':
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self::_replace($word, 'er', '', 1);
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break;
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case 'i':
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self::_replace($word, 'ic', '', 1);
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break;
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case 'l':
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self::_replace($word, 'able', '', 1)
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or self::_replace($word, 'ible', '', 1);
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break;
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case 'n':
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self::_replace($word, 'ant', '', 1)
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or self::_replace($word, 'ement', '', 1)
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or self::_replace($word, 'ment', '', 1)
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or self::_replace($word, 'ent', '', 1);
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break;
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case 'o':
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if (substr($word, -4) == 'tion' or substr($word, -4) == 'sion')
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{
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self::_replace($word, 'ion', '', 1);
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}
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else
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{
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self::_replace($word, 'ou', '', 1);
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}
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break;
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case 's':
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self::_replace($word, 'ism', '', 1);
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break;
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case 't':
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self::_replace($word, 'ate', '', 1)
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or self::_replace($word, 'iti', '', 1);
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break;
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case 'u':
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self::_replace($word, 'ous', '', 1);
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break;
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case 'v':
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self::_replace($word, 'ive', '', 1);
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break;
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case 'z':
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self::_replace($word, 'ize', '', 1);
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break;
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}
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return $word;
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}
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/**
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* Step 5
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*
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* @param string $word The token to stem.
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*
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* @return string
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*
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* @since 12.1
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*/
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private static function _step5($word)
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{
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// Part a
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if (substr($word, -1) == 'e')
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{
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if (self::_m(substr($word, 0, -1)) > 1)
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{
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self::_replace($word, 'e', '');
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}
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elseif (self::_m(substr($word, 0, -1)) == 1)
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{
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if (!self::_cvc(substr($word, 0, -1)))
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{
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self::_replace($word, 'e', '');
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}
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}
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}
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// Part b
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if (self::_m($word) > 1 and self::_doubleConsonant($word) and substr($word, -1) == 'l')
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{
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$word = substr($word, 0, -1);
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}
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return $word;
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}
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/**
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* Replaces the first string with the second, at the end of the string. If third
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* arg is given, then the preceding string must match that m count at least.
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*
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* @param string &$str String to check
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* @param string $check Ending to check for
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* @param string $repl Replacement string
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* @param integer $m Optional minimum number of m() to meet
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*
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* @return boolean Whether the $check string was at the end
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* of the $str string. True does not necessarily mean
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* that it was replaced.
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*
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* @since 12.1
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*/
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private static function _replace(&$str, $check, $repl, $m = null)
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{
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$len = 0 - strlen($check);
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if (substr($str, $len) == $check)
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{
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$substr = substr($str, 0, $len);
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if (is_null($m) or self::_m($substr) > $m)
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{
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$str = $substr . $repl;
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}
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return true;
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}
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return false;
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}
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/**
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* m() measures the number of consonant sequences in $str. if c is
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* a consonant sequence and v a vowel sequence, and <..> indicates arbitrary
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* presence,
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*
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* <c><v> gives 0
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* <c>vc<v> gives 1
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* <c>vcvc<v> gives 2
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* <c>vcvcvc<v> gives 3
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*
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* @param string $str The string to return the m count for
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*
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* @return integer The m count
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*
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* @since 12.1
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*/
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private static function _m($str)
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{
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$c = self::$_regex_consonant;
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$v = self::$_regex_vowel;
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$str = preg_replace("#^$c+#", '', $str);
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$str = preg_replace("#$v+$#", '', $str);
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preg_match_all("#($v+$c+)#", $str, $matches);
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return count($matches[1]);
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}
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/**
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* Returns true/false as to whether the given string contains two
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* of the same consonant next to each other at the end of the string.
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*
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* @param string $str String to check
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*
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* @return boolean Result
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*
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* @since 12.1
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*/
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private static function _doubleConsonant($str)
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{
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$c = self::$_regex_consonant;
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return preg_match("#$c{2}$#", $str, $matches) and $matches[0]{0} == $matches[0]{1};
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}
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/**
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* Checks for ending CVC sequence where second C is not W, X or Y
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*
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* @param string $str String to check
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*
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* @return boolean Result
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*
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* @since 12.1
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*/
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private static function _cvc($str)
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{
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$c = self::$_regex_consonant;
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$v = self::$_regex_vowel;
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$result = preg_match("#($c$v$c)$#", $str, $matches)
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and strlen($matches[1]) == 3
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and $matches[1]{2} != 'w'
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and $matches[1]{2} != 'x'
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and $matches[1]{2} != 'y';
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return $result;
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}
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}
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