<?php
/**
* Singularize a string.
* Converts a word to english singular form.
*
* Usage example:
* {singularize "people"} # person
*/
function singularize ($params)
{
    if (is_string($params))
    {
        $word = $params;
    } else if (!$word = $params['word']) {
        return false;
    }

    $singular = array (
        '/(quiz)zes$/i' => '\\1',
        '/(matr)ices$/i' => '\\1ix',
        '/(vert|ind)ices$/i' => '\\1ex',
        '/^(ox)en/i' => '\\1',
        '/(alias|status)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',
        '/([^f])ves$/i' => '\\1fe',
        '/(^analy)ses$/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$/i' => '\\1ews',
        '/s$/i' => ''
    );

    $irregular = array(
        'person' => 'people',
        'man' => 'men',
        'child' => 'children',
        'sex' => 'sexes',
        'move' => 'moves'
    );	

    $ignore = array(
        'equipment',
        'information',
        'rice',
        'money',
        'species',
        'series',
        'fish',
        'sheep',
        'press',
        'sms',
    );

    $lower_word = strtolower($word);
    foreach ($ignore as $ignore_word)
    {
        if (substr($lower_word, (-1 * strlen($ignore_word))) == $ignore_word)
        {
            return $word;
        }
    }

    foreach ($irregular as $singular_word => $plural_word)
    {
        if (preg_match('/('.$plural_word.')$/i', $word, $arr))
        {
            return preg_replace('/('.$plural_word.')$/i', substr($arr[0],0,1).substr($singular_word,1), $word);
        }
    }

    foreach ($singular as $rule => $replacement)
    {
        if (preg_match($rule, $word))
        {
            return preg_replace($rule, $replacement, $word);
        }
    }

    return $word;
}