Singular and Plural keywords index

Automatic singularization and pluralization of English keywords

Use the custom code snippet below to automatically singularize and pluralize English keywords when using the Index Table engine. This algorightm is efficient, but of course not a 100% accurate.

After adding the code a new index must be generated

What is this, and where do I put this custom code?

// ---- !!! ONLY COPY PASTE CODE BELOW THIS LINE to the functions.php in your theme directory !!! ----// ---- AJAX SEARCH PRO: BEGIN SEMI-AUTOMATIC PLURALIZATION OF ENGLISH KEYWORDS -----
class Inflect
{
    static $plural = array(
        '/(quiz)$/i'               => "$1zes",
        '/^(ox)$/i'                => "$1en",
        '/([m|l])ouse$/i'          => "$1ice",
        '/(matr|vert|ind)ix|ex$/i' => "$1ices",
        '/(x|ch|ss|sh)$/i'         => "$1es",
        '/([^aeiouy]|qu)y$/i'      => "$1ies",
        '/(hive)$/i'               => "$1s",
        '/(?:([^f])fe|([lr])f)$/i' => "$1$2ves",
        '/(shea|lea|loa|thie)f$/i' => "$1ves",
        '/sis$/i'                  => "ses",
        '/([ti])um$/i'             => "$1a",
        '/(tomat|potat|ech|her|vet)o$/i'=> "$1oes",
        '/(bu)s$/i'                => "$1ses",
        '/(alias)$/i'              => "$1es",
        '/(octop)us$/i'            => "$1i",
        '/(ax|test)is$/i'          => "$1es",
        '/(us)$/i'                 => "$1es",
        '/s$/i'                    => "s",
        '/$/'                      => "s"
    );
    
    static $singular = array(
        '/(quiz)zes$/i'             => "$1",
        '/(matr)ices$/i'            => "$1ix",
        '/(vert|ind)ices$/i'        => "$1ex",
        '/^(ox)en$/i'               => "$1",
        '/(alias)es$/i'             => "$1",
        '/(octop|vir)i$/i'          => "$1us",
        '/(cris|ax|test)es$/i'      => "$1is",
        '/(shoe)s$/i'               => "$1",
        '/(o)es$/i'                 => "$1",
        '/(bus)es$/i'               => "$1",
        '/([m|l])ice$/i'            => "$1ouse",
        '/(x|ch|ss|sh)es$/i'        => "$1",
        '/(m)ovies$/i'              => "$1ovie",
        '/(s)eries$/i'              => "$1eries",
        '/([^aeiouy]|qu)ies$/i'     => "$1y",
        '/([lr])ves$/i'             => "$1f",
        '/(tive)s$/i'               => "$1",
        '/(hive)s$/i'               => "$1",
        '/(li|wi|kni)ves$/i'        => "$1fe",
        '/(shea|loa|lea|thie)ves$/i'=> "$1f",
        '/(^analy)ses$/i'           => "$1sis",
        '/((a)naly|(b)a|(d)iagno|(p)arenthe|(p)rogno|(s)ynop|(t)he)ses$/i'  => "$1$2sis",        
        '/([ti])a$/i'               => "$1um",
        '/(n)ews$/i'                => "$1ews",
        '/(h|bl)ouses$/i'           => "$1ouse",
        '/(corpse)s$/i'             => "$1",
        '/(us)es$/i'                => "$1",
        '/s$/i'                     => ""
    );
    
    static $irregular = array(
        'move'   => 'moves',
        'foot'   => 'feet',
        'goose'  => 'geese',
        'sex'    => 'sexes',
        'child'  => 'children',
        'man'    => 'men',
        'tooth'  => 'teeth',
        'person' => 'people'
    );
    
    static $uncountable = array( 
        'sheep', 
        'fish',
        'deer',
        'series',
        'species',
        'money',
        'rice',
        'information',
        'equipment'
    );
    
    public static function pluralize( $string ) 
    {
        // save some time in the case that singular and plural are the same
        if ( in_array( strtolower( $string ), self::$uncountable ) )
            return $string;
            
    
        // check for irregular singular forms
        foreach ( self::$irregular as $pattern => $result )
        {
            $pattern = '/' . $pattern . '$/i';
            
            if ( preg_match( $pattern, $string ) )
                return preg_replace( $pattern, $result, $string);
        }
        
        // check for matches using regular expressions
        foreach ( self::$plural as $pattern => $result )
        {
            if ( preg_match( $pattern, $string ) )
                return preg_replace( $pattern, $result, $string );
        }
        
        return $string;
    }
    
    public static function singularize( $string )
    {
        // save some time in the case that singular and plural are the same
        if ( in_array( strtolower( $string ), self::$uncountable ) )
            return $string;

        // check for irregular plural forms
        foreach ( self::$irregular as $result => $pattern )
        {
            $pattern = '/' . $pattern . '$/i';
            
            if ( preg_match( $pattern, $string ) )
                return preg_replace( $pattern, $result, $string);
        }
        
        // check for matches using regular expressions
        foreach ( self::$singular as $pattern => $result )
        {
            if ( preg_match( $pattern, $string ) )
                return preg_replace( $pattern, $result, $string );
        }
        
        return $string;
    }
    
    public static function pluralize_if($count, $string)
    {
        if ($count == 1)
            return "1 $string";
        else
            return $count . " " . self::pluralize($string);
    }
}

add_filter( 'asp_indexing_string_post_process', 'asp_index_add_singular_plural', 10, 1 );
function asp_index_add_singular_plural($s) {
    $final = array();
	$words = explode(' ', $s);
	
    foreach ($words as $word) {
        $singular = Inflect::singularize($word);
        $plural = Inflect::pluralize($word);

        $final[] = $word;

        if ($singular != $word)
            $final[] = $singular;

        if ($plural != $word)
            $final[] = $plural;
    }
	
    return implode(' ', $final);
}
// ---- AJAX SEARCH PRO: END SEMI-AUTOMATIC PLURALIZATION OF ENGLISH KEYWORDS -----
// --------------------------------------------------------------------------------