ASP: Index table singular and plural keyword conversion

functions.php

<?php
// ---- !!! 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 -----
// --------------------------------------------------------------------------------