English stemmer

gistfile1.php

class StemmerEnglish{

  function pluralize($word) {
		$pos    = strlen($word)-1;
		// Check last letter
		switch ($word{$pos}) {
			case 's':     // Maby already plural
			if ($word{$pos-1} == 's')
			return $word.'es';
			else
			return $word;
			case 'o':    // Check for exceptions
			if ($word == 'kilo' || $word == 'photo' || $word == 'piano' || $word == 'soprano')
			break;
			return $word.'es';
			case 'h':    // Check letter before lat
			$letter = $word{$pos-1};
			if ($letter == 's' || $letter == 'c')
			return $word.'es';
			break;
			case 'e':    // Check previous letter
			if ($word{strlen($word)-2} != 'f') {
				// Check for exceptions
				switch ($word) {
					case 'mouse':    return 'mice';
					case 'goose':    return 'geese';
					case 'louse':    return 'lice';
				}
				break;
			}
			$word = substr($word, 0, $pos);
			case 'f':    $word = substr($word, 0, strlen($word)-1).'v';
			return $word.'es';
			case 'x':    // Check for exception
			if ($word == 'ox')
			return 'oxen';
			return $word.'es';
			case 'y':    // Check before last letter
			switch ($word{$pos-1}) {
				case 'a':
				case 'e':
				case 'i':
				case 'o':
				case 'u':
				case 'y':    break;
				default:    return substr($word, 0, $pos).'ies';
			}
			break;
			default:    // Check for exceptions
			switch ($word) {
				case 'foot':    return 'feet';
				case 'tooth':    return 'teeth';
				case 'man':    return 'men';
				case 'woman':    return 'women';
				case 'child':    return 'children';
				case 'sheep':
				case 'deer':    return $word;
			}
		}
		return $word.'s';
	}

	function singularize($word) {
		$pos = strlen($word)-1;
		// Check is word can be in plural form
		if ($word{$pos} != 's')
		// Check for exception word
		switch ($word) {
			case 'mice':    return 'mouse';
			case 'geese':    return 'goose';
			case 'lise':    return 'louse';
			case 'feet':    return 'foot';
			case 'teeth':    return 'tooth';
			case 'men':    return 'man';
			case 'women':    return 'woman';
			case 'children':return 'child';
			case 'oxen':    return 'ox';
			default:    return $word;
		}
		// Check letter before last
		switch ($word{$pos-1}) {
			// Already singular form
			case 's':    return $word;
			case 'e':    // Additinal checking. Needed to find correct forms
			switch ($word{$pos-2}) {
				case 'h':    // Check additional rules
				if ($word{$pos-3} != 's' && $word{$pos-3} != 'c')
				break;
				return substr($word, 0, $pos-1);
				case 'i':    // Remplace 'i' with 'y' and remove last two chars
				return substr($word, 0, $pos-2).'y';
				case 'v':    // Replace 'v' with 'f'
				$word{$pos-2} = 'f';
				if ($word == 'knifes' || $word == 'wifes' || $word == 'lifes')
				break;
				case 'o':    // Need to remove last two chars
				case 'x':    // Remove last two chars
				return substr($word, 0, $pos-1);
				case 's':    // Check for letter before s
				if ($word{$pos-3} == 's')
				return substr($word, 0, $pos-1);
			}
		}
		// Usual way - remove last 's' letter
		return substr($word, 0, $pos);
	}
}