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externals/porter-stemmer/src/Porter.php
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| <?php | |||||
| # vim: set expandtab tabstop=4 shiftwidth=4 softtabstop=4: | |||||
| /** | |||||
| * Copyright (c) 2005-2016 Richard Heyes (http://www.phpguru.org/) | |||||
| * | |||||
| * Portions Copyright 2003-2007 Jon Abernathy <jon@chuggnutt.com> | |||||
| * | |||||
| * Originally available under the GPL 2 or greater. Relicensed with permission | |||||
| * of original authors under the MIT License in 2016. | |||||
| * | |||||
| * All rights reserved. | |||||
| * | |||||
| * @package PorterStemmer | |||||
| * @author Richard Heyes | |||||
| * @author Jon Abernathy <jon@chuggnutt.com> | |||||
| * @copyright 2005-2016 Richard Heyes (http://www.phpguru.org/) | |||||
| * @license http://www.opensource.org/licenses/mit-license.html MIT License | |||||
| */ | |||||
| /** | |||||
| * PHP 5 Implementation of the Porter Stemmer algorithm. Certain elements | |||||
| * were borrowed from the (broken) implementation by Jon Abernathy. | |||||
| * | |||||
| * See http://tartarus.org/~martin/PorterStemmer/ for a description of the | |||||
| * algorithm. | |||||
| * | |||||
| * Usage: | |||||
| * | |||||
| * $stem = PorterStemmer::Stem($word); | |||||
| * | |||||
| * How easy is that? | |||||
| * | |||||
| * @package PorterStemmer | |||||
| * @author Richard Heyes | |||||
| * @author Jon Abernathy <jon@chuggnutt.com> | |||||
| * @copyright 2005-2016 Richard Heyes (http://www.phpguru.org/) | |||||
| * @license http://www.opensource.org/licenses/mit-license.html MIT License | |||||
| */ | |||||
| class Porter | |||||
| { | |||||
| /** | |||||
| * Regex for matching a consonant | |||||
| * | |||||
| * @var string | |||||
| */ | |||||
| private static $regex_consonant = '(?:[bcdfghjklmnpqrstvwxz]|(?<=[aeiou])y|^y)'; | |||||
| /** | |||||
| * Regex for matching a vowel | |||||
| * | |||||
| * @var string | |||||
| */ | |||||
| private static $regex_vowel = '(?:[aeiou]|(?<![aeiou])y)'; | |||||
| /** | |||||
| * Stems a word. Simple huh? | |||||
| * | |||||
| * @param string $word Word to stem | |||||
| * | |||||
| * @return string Stemmed word | |||||
| */ | |||||
| public static function Stem($word) | |||||
| { | |||||
| if (strlen($word) <= 2) { | |||||
| return $word; | |||||
| } | |||||
| $word = self::step1ab($word); | |||||
| $word = self::step1c($word); | |||||
| $word = self::step2($word); | |||||
| $word = self::step3($word); | |||||
| $word = self::step4($word); | |||||
| $word = self::step5($word); | |||||
| return $word; | |||||
| } | |||||
| /** | |||||
| * Step 1 | |||||
| */ | |||||
| private static function step1ab($word) | |||||
| { | |||||
| // Part a | |||||
| if (substr($word, -1) == 's') { | |||||
| self::replace($word, 'sses', 'ss') | |||||
| OR self::replace($word, 'ies', 'i') | |||||
| OR self::replace($word, 'ss', 'ss') | |||||
| OR self::replace($word, 's', ''); | |||||
| } | |||||
| // Part b | |||||
| if (substr($word, -2, 1) != 'e' OR !self::replace($word, 'eed', 'ee', 0)) { // First rule | |||||
| $v = self::$regex_vowel; | |||||
| // ing and ed | |||||
| if ( preg_match("#$v+#", substr($word, 0, -3)) && self::replace($word, 'ing', '') | |||||
| OR preg_match("#$v+#", substr($word, 0, -2)) && self::replace($word, 'ed', '')) { // Note use of && and OR, for precedence reasons | |||||
| // If one of above two test successful | |||||
| if ( !self::replace($word, 'at', 'ate') | |||||
| AND !self::replace($word, 'bl', 'ble') | |||||
| AND !self::replace($word, 'iz', 'ize')) { | |||||
| // Double consonant ending | |||||
| if ( self::doubleConsonant($word) | |||||
| AND substr($word, -2) != 'll' | |||||
| AND substr($word, -2) != 'ss' | |||||
| AND substr($word, -2) != 'zz') { | |||||
| $word = substr($word, 0, -1); | |||||
| } elseif (self::m($word) == 1 AND self::cvc($word)) { | |||||
| $word .= 'e'; | |||||
| } | |||||
| } | |||||
| } | |||||
| } | |||||
| return $word; | |||||
| } | |||||
| /** | |||||
| * Step 1c | |||||
| * | |||||
| * @param string $word Word to stem | |||||
| */ | |||||
| private static function step1c($word) | |||||
| { | |||||
| $v = self::$regex_vowel; | |||||
| if (substr($word, -1) == 'y' && preg_match("#$v+#", substr($word, 0, -1))) { | |||||
| self::replace($word, 'y', 'i'); | |||||
| } | |||||
| return $word; | |||||
| } | |||||
| /** | |||||
| * Step 2 | |||||
| * | |||||
| * @param string $word Word to stem | |||||
| */ | |||||
| private static function step2($word) | |||||
| { | |||||
| switch (substr($word, -2, 1)) { | |||||
| case 'a': | |||||
| self::replace($word, 'ational', 'ate', 0) | |||||
| OR self::replace($word, 'tional', 'tion', 0); | |||||
| break; | |||||
| case 'c': | |||||
| self::replace($word, 'enci', 'ence', 0) | |||||
| OR self::replace($word, 'anci', 'ance', 0); | |||||
| break; | |||||
| case 'e': | |||||
| self::replace($word, 'izer', 'ize', 0); | |||||
| break; | |||||
| case 'g': | |||||
| self::replace($word, 'logi', 'log', 0); | |||||
| break; | |||||
| case 'l': | |||||
| self::replace($word, 'entli', 'ent', 0) | |||||
| OR self::replace($word, 'ousli', 'ous', 0) | |||||
| OR self::replace($word, 'alli', 'al', 0) | |||||
| OR self::replace($word, 'bli', 'ble', 0) | |||||
| OR self::replace($word, 'eli', 'e', 0); | |||||
| break; | |||||
| case 'o': | |||||
| self::replace($word, 'ization', 'ize', 0) | |||||
| OR self::replace($word, 'ation', 'ate', 0) | |||||
| OR self::replace($word, 'ator', 'ate', 0); | |||||
| break; | |||||
| case 's': | |||||
| self::replace($word, 'iveness', 'ive', 0) | |||||
| OR self::replace($word, 'fulness', 'ful', 0) | |||||
| OR self::replace($word, 'ousness', 'ous', 0) | |||||
| OR self::replace($word, 'alism', 'al', 0); | |||||
| break; | |||||
| case 't': | |||||
| self::replace($word, 'biliti', 'ble', 0) | |||||
| OR self::replace($word, 'aliti', 'al', 0) | |||||
| OR self::replace($word, 'iviti', 'ive', 0); | |||||
| break; | |||||
| } | |||||
| return $word; | |||||
| } | |||||
| /** | |||||
| * Step 3 | |||||
| * | |||||
| * @param string $word String to stem | |||||
| */ | |||||
| private static function step3($word) | |||||
| { | |||||
| switch (substr($word, -2, 1)) { | |||||
| case 'a': | |||||
| self::replace($word, 'ical', 'ic', 0); | |||||
| break; | |||||
| case 's': | |||||
| self::replace($word, 'ness', '', 0); | |||||
| break; | |||||
| case 't': | |||||
| self::replace($word, 'icate', 'ic', 0) | |||||
| OR self::replace($word, 'iciti', 'ic', 0); | |||||
| break; | |||||
| case 'u': | |||||
| self::replace($word, 'ful', '', 0); | |||||
| break; | |||||
| case 'v': | |||||
| self::replace($word, 'ative', '', 0); | |||||
| break; | |||||
| case 'z': | |||||
| self::replace($word, 'alize', 'al', 0); | |||||
| break; | |||||
| } | |||||
| return $word; | |||||
| } | |||||
| /** | |||||
| * Step 4 | |||||
| * | |||||
| * @param string $word Word to stem | |||||
| */ | |||||
| private static function step4($word) | |||||
| { | |||||
| switch (substr($word, -2, 1)) { | |||||
| case 'a': | |||||
| self::replace($word, 'al', '', 1); | |||||
| break; | |||||
| case 'c': | |||||
| self::replace($word, 'ance', '', 1) | |||||
| OR self::replace($word, 'ence', '', 1); | |||||
| break; | |||||
| case 'e': | |||||
| self::replace($word, 'er', '', 1); | |||||
| break; | |||||
| case 'i': | |||||
| self::replace($word, 'ic', '', 1); | |||||
| break; | |||||
| case 'l': | |||||
| self::replace($word, 'able', '', 1) | |||||
| OR self::replace($word, 'ible', '', 1); | |||||
| break; | |||||
| case 'n': | |||||
| self::replace($word, 'ant', '', 1) | |||||
| OR self::replace($word, 'ement', '', 1) | |||||
| OR self::replace($word, 'ment', '', 1) | |||||
| OR self::replace($word, 'ent', '', 1); | |||||
| break; | |||||
| case 'o': | |||||
| if (substr($word, -4) == 'tion' OR substr($word, -4) == 'sion') { | |||||
| self::replace($word, 'ion', '', 1); | |||||
| } else { | |||||
| self::replace($word, 'ou', '', 1); | |||||
| } | |||||
| break; | |||||
| case 's': | |||||
| self::replace($word, 'ism', '', 1); | |||||
| break; | |||||
| case 't': | |||||
| self::replace($word, 'ate', '', 1) | |||||
| OR self::replace($word, 'iti', '', 1); | |||||
| break; | |||||
| case 'u': | |||||
| self::replace($word, 'ous', '', 1); | |||||
| break; | |||||
| case 'v': | |||||
| self::replace($word, 'ive', '', 1); | |||||
| break; | |||||
| case 'z': | |||||
| self::replace($word, 'ize', '', 1); | |||||
| break; | |||||
| } | |||||
| return $word; | |||||
| } | |||||
| /** | |||||
| * Step 5 | |||||
| * | |||||
| * @param string $word Word to stem | |||||
| */ | |||||
| private static function step5($word) | |||||
| { | |||||
| // Part a | |||||
| if (substr($word, -1) == 'e') { | |||||
| if (self::m(substr($word, 0, -1)) > 1) { | |||||
| self::replace($word, 'e', ''); | |||||
| } elseif (self::m(substr($word, 0, -1)) == 1) { | |||||
| if (!self::cvc(substr($word, 0, -1))) { | |||||
| self::replace($word, 'e', ''); | |||||
| } | |||||
| } | |||||
| } | |||||
| // Part b | |||||
| if (self::m($word) > 1 AND self::doubleConsonant($word) AND substr($word, -1) == 'l') { | |||||
| $word = substr($word, 0, -1); | |||||
| } | |||||
| return $word; | |||||
| } | |||||
| /** | |||||
| * Replaces the first string with the second, at the end of the string | |||||
| * | |||||
| * If third arg is given, then the preceding string must match that m | |||||
| * count at least. | |||||
| * | |||||
| * @param string $str String to check | |||||
| * @param string $check Ending to check for | |||||
| * @param string $repl Replacement string | |||||
| * @param int $m Optional minimum number of m() to meet | |||||
| * | |||||
| * @return bool Whether the $check string was at the end of the $str | |||||
| * string. True does not necessarily mean that it was | |||||
| * replaced. | |||||
| */ | |||||
| private static function replace(&$str, $check, $repl, $m = null) | |||||
| { | |||||
| $len = 0 - strlen($check); | |||||
| if (substr($str, $len) == $check) { | |||||
| $substr = substr($str, 0, $len); | |||||
| if (is_null($m) OR self::m($substr) > $m) { | |||||
| $str = $substr . $repl; | |||||
| } | |||||
| return true; | |||||
| } | |||||
| return false; | |||||
| } | |||||
| /** | |||||
| * What, you mean it's not obvious from the name? | |||||
| * | |||||
| * m() measures the number of consonant sequences in $str. if c is | |||||
| * a consonant sequence and v a vowel sequence, and <..> indicates arbitrary | |||||
| * presence, | |||||
| * | |||||
| * <c><v> gives 0 | |||||
| * <c>vc<v> gives 1 | |||||
| * <c>vcvc<v> gives 2 | |||||
| * <c>vcvcvc<v> gives 3 | |||||
| * | |||||
| * @param string $str The string to return the m count for | |||||
| * | |||||
| * @return int The m count | |||||
| */ | |||||
| private static function m($str) | |||||
| { | |||||
| $c = self::$regex_consonant; | |||||
| $v = self::$regex_vowel; | |||||
| $str = preg_replace("#^$c+#", '', $str); | |||||
| $str = preg_replace("#$v+$#", '', $str); | |||||
| preg_match_all("#($v+$c+)#", $str, $matches); | |||||
| return count($matches[1]); | |||||
| } | |||||
| /** | |||||
| * Returns true/false as to whether the given string contains two | |||||
| * of the same consonant next to each other at the end of the string. | |||||
| * | |||||
| * @param string $str String to check | |||||
| * | |||||
| * @return bool Result | |||||
| */ | |||||
| private static function doubleConsonant($str) | |||||
| { | |||||
| $c = self::$regex_consonant; | |||||
| return preg_match("#$c{2}$#", $str, $matches) AND $matches[0]{0} == $matches[0]{1}; | |||||
| } | |||||
| /** | |||||
| * Checks for ending CVC sequence where second C is not W, X or Y | |||||
| * | |||||
| * @param string $str String to check | |||||
| * | |||||
| * @return bool Result | |||||
| */ | |||||
| private static function cvc($str) | |||||
| { | |||||
| $c = self::$regex_consonant; | |||||
| $v = self::$regex_vowel; | |||||
| return preg_match("#($c$v$c)$#", $str, $matches) | |||||
| AND strlen($matches[1]) == 3 | |||||
| AND $matches[1]{2} != 'w' | |||||
| AND $matches[1]{2} != 'x' | |||||
| AND $matches[1]{2} != 'y'; | |||||
| } | |||||
| } | |||||