<?php
/**
* Part of the Joomla Framework Language Package
*
* @copyright Copyright (C) 2005 - 2020 Open Source Matters, Inc. All rights reserved.
* @copyright Copyright (C) 2005 Richard Heyes (http://www.phpguru.org/). All rights reserved.
* @license GNU General Public License version 2 or later; see LICENSE
*/
namespace Joomla\Language\Stemmer;
use Joomla\Language\StemmerInterface;
/**
* Porter English stemmer class.
*
* This class was adapted from one written by Richard Heyes.
* See copyright and link information above.
*
* @since 1.0
*/
class Porteren implements StemmerInterface
{
/**
* An internal cache of stemmed tokens.
*
* @var array
* @since 1.0
*/
protected $cache = [];
/**
* Regex for matching a consonant.
*
* @var string
* @since 1.4.0
*/
private $regexConsonant = '(?:[bcdfghjklmnpqrstvwxz]|(?<=[aeiou])y|^y)';
/**
* Regex for matching a vowel
*
* @var string
* @since 1.4.0
*/
private $regexVowel = '(?:[aeiou]|(?<![aeiou])y)';
/**
* Method to stem a token and return the root.
*
* @param string $token The token to stem.
* @param string $lang The language of the token.
*
* @return string The root token.
*
* @since 1.0
*/
public function stem($token, $lang)
{
// Check if the token is long enough to merit stemming.
if (\strlen($token) <= 2) {
return $token;
}
// Check if the language is English or All.
if ($lang !== 'en') {
return $token;
}
// Stem the token if it is not in the cache.
if (!isset($this->cache[$lang][$token])) {
// Stem the token.
$result = $token;
$result = $this->step1ab($result);
$result = $this->step1c($result);
$result = $this->step2($result);
$result = $this->step3($result);
$result = $this->step4($result);
$result = $this->step5($result);
// Add the token to the cache.
$this->cache[$lang][$token] = $result;
}
return $this->cache[$lang][$token];
}
/**
* Step 1
*
* @param string $word The token to stem.
*
* @return string
*
* @since 1.0
*/
private function step1ab($word)
{
// Part a
if (substr($word, -1) == 's') {
$this->replace($word, 'sses', 'ss')
|| $this->replace($word, 'ies', 'i')
|| $this->replace($word, 'ss', 'ss')
|| $this->replace($word, 's', '');
}
// Part b
if (substr($word, -2, 1) != 'e' || !$this->replace($word, 'eed', 'ee', 0)) {
// First rule
$v = $this->regexVowel;
// Check ing and ed
// Note use of && and OR, for precedence reasons
if (
preg_match("#$v+#", substr($word, 0, -3)) && $this->replace($word, 'ing', '')
|| preg_match("#$v+#", substr($word, 0, -2)) && $this->replace($word, 'ed', '')
) {
// If one of above two test successful
if (!$this->replace($word, 'at', 'ate') && !$this->replace($word, 'bl', 'ble') && !$this->replace($word, 'iz', 'ize')) {
// Double consonant ending
if ($this->doubleConsonant($word) && substr($word, -2) != 'll' && substr($word, -2) != 'ss' && substr($word, -2) != 'zz') {
$word = substr($word, 0, -1);
} elseif ($this->m($word) == 1 && $this->cvc($word)) {
$word .= 'e';
}
}
}
}
return $word;
}
/**
* Step 1c
*
* @param string $word The token to stem.
*
* @return string
*
* @since 1.0
*/
private function step1c($word)
{
$v = $this->regexVowel;
if (substr($word, -1) == 'y' && preg_match("#$v+#", substr($word, 0, -1))) {
$this->replace($word, 'y', 'i');
}
return $word;
}
/**
* Step 2
*
* @param string $word The token to stem.
*
* @return string
*
* @since 1.0
*/
private function step2($word)
{
switch (substr($word, -2, 1)) {
case 'a':
$this->replace($word, 'ational', 'ate', 0)
|| $this->replace($word, 'tional', 'tion', 0);
break;
case 'c':
$this->replace($word, 'enci', 'ence', 0)
|| $this->replace($word, 'anci', 'ance', 0);
break;
case 'e':
$this->replace($word, 'izer', 'ize', 0);
break;
case 'g':
$this->replace($word, 'logi', 'log', 0);
break;
case 'l':
$this->replace($word, 'entli', 'ent', 0)
|| $this->replace($word, 'ousli', 'ous', 0)
|| $this->replace($word, 'alli', 'al', 0)
|| $this->replace($word, 'bli', 'ble', 0)
|| $this->replace($word, 'eli', 'e', 0);
break;
case 'o':
$this->replace($word, 'ization', 'ize', 0)
|| $this->replace($word, 'ation', 'ate', 0)
|| $this->replace($word, 'ator', 'ate', 0);
break;
case 's':
$this->replace($word, 'iveness', 'ive', 0)
|| $this->replace($word, 'fulness', 'ful', 0)
|| $this->replace($word, 'ousness', 'ous', 0)
|| $this->replace($word, 'alism', 'al', 0);
break;
case 't':
$this->replace($word, 'biliti', 'ble', 0)
|| $this->replace($word, 'aliti', 'al', 0)
|| $this->replace($word, 'iviti', 'ive', 0);
break;
}
return $word;
}
/**
* Step 3
*
* @param string $word The token to stem.
*
* @return string
*
* @since 1.0
*/
private function step3($word)
{
switch (substr($word, -2, 1)) {
case 'a':
$this->replace($word, 'ical', 'ic', 0);
break;
case 's':
$this->replace($word, 'ness', '', 0);
break;
case 't':
$this->replace($word, 'icate', 'ic', 0)
|| $this->replace($word, 'iciti', 'ic', 0);
break;
case 'u':
$this->replace($word, 'ful', '', 0);
break;
case 'v':
$this->replace($word, 'ative', '', 0);
break;
case 'z':
$this->replace($word, 'alize', 'al', 0);
break;
}
return $word;
}
/**
* Step 4
*
* @param string $word The token to stem.
*
* @return string
*
* @since 1.0
*/
private function step4($word)
{
switch (substr($word, -2, 1)) {
case 'a':
$this->replace($word, 'al', '', 1);
break;
case 'c':
$this->replace($word, 'ance', '', 1)
|| $this->replace($word, 'ence', '', 1);
break;
case 'e':
$this->replace($word, 'er', '', 1);
break;
case 'i':
$this->replace($word, 'ic', '', 1);
break;
case 'l':
$this->replace($word, 'able', '', 1)
|| $this->replace($word, 'ible', '', 1);
break;
case 'n':
$this->replace($word, 'ant', '', 1)
|| $this->replace($word, 'ement', '', 1)
|| $this->replace($word, 'ment', '', 1)
|| $this->replace($word, 'ent', '', 1);
break;
case 'o':
if (substr($word, -4) == 'tion' || substr($word, -4) == 'sion') {
$this->replace($word, 'ion', '', 1);
} else {
$this->replace($word, 'ou', '', 1);
}
break;
case 's':
$this->replace($word, 'ism', '', 1);
break;
case 't':
$this->replace($word, 'ate', '', 1)
|| $this->replace($word, 'iti', '', 1);
break;
case 'u':
$this->replace($word, 'ous', '', 1);
break;
case 'v':
$this->replace($word, 'ive', '', 1);
break;
case 'z':
$this->replace($word, 'ize', '', 1);
break;
}
return $word;
}
/**
* Step 5
*
* @param string $word The token to stem.
*
* @return string
*
* @since 1.0
*/
private function step5($word)
{
// Part a
if (substr($word, -1) == 'e') {
if ($this->m(substr($word, 0, -1)) > 1) {
$this->replace($word, 'e', '');
} elseif ($this->m(substr($word, 0, -1)) == 1) {
if (!$this->cvc(substr($word, 0, -1))) {
$this->replace($word, 'e', '');
}
}
}
// Part b
if ($this->m($word) > 1 && $this->doubleConsonant($word) && 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 integer $m Optional minimum number of m() to meet
*
* @return boolean Whether the $check string was at the end
* of the $str string. True does not necessarily mean
* that it was replaced.
*
* @since 1.0
*/
private function replace(&$str, $check, $repl, $m = null)
{
$len = 0 - \strlen($check);
if (substr($str, $len) == $check) {
$substr = substr($str, 0, $len);
if ($m === null || $this->m($substr) > $m) {
$str = $substr . $repl;
}
return true;
}
return false;
}
/**
* 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 $str The string to return the m count for
*
* @return integer The m count
*
* @since 1.0
*/
private function m($str)
{
$c = $this->regexConsonant;
$v = $this->regexVowel;
$str = preg_replace("#^$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 $str String to check
*
* @return boolean Result
*
* @since 1.0
*/
private function doubleConsonant($str)
{
$c = $this->regexConsonant;
return preg_match("#$c{2}$#", $str, $matches) && $matches[0][0] === $matches[0][1];
}
/**
* Checks for ending CVC sequence where second C is not W, X or Y
*
* @param string $str String to check
*
* @return boolean Result
*
* @since 1.0
*/
private function cvc($str)
{
$c = $this->regexConsonant;
$v = $this->regexVowel;
return preg_match("#($c$v$c)$#", $str, $matches)
&& \strlen($matches[1]) === 3
&& $matches[1][2] !== 'w'
&& $matches[1][2] !== 'x'
&& $matches[1][2] !== 'y';
}
}