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phorge-phorge/externals/porter-stemmer/src/Porter.php
epriestley db6b4ca480 Update deprecated array access syntax in Porter stemmer
Summary: Fixes T13472. This library uses `$a{0}`, but this is deprecated in favor of `$a[0]`.

Test Plan:
Ran `bin/search index Txxx --force` on a task with "filing" in the title (this term reaches the "m" rule of the stemmer).

(I'm not on new enough PHP for this to actually raise an error, but I'll follow up with the reporting user.)

Maniphest Tasks: T13472

Differential Revision: https://secure.phabricator.com/D20941
2020-01-14 12:11:39 -08:00

426 lines
12 KiB
PHP

<?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';
}
}