Hanging punctuation class

<?php
/**
 * Класс для добавления весячей пунктуации
 */
class Hanging extends CApplicationComponent {
    // Константы классов
    const CLASS_QUOTE_LEFT = 1;
    const CLASS_QUOTE_RIGHT = 2;
    const CLASS_BKT_LEFT = 3;
    const CLASS_BKT_RIGHT = 4;

    // HTML-классы
    public $class_quote_left = 'punct-ql';
    public $class_quote_right = 'punct-qr';
    public $class_bkt_left = 'punct-ls';
    public $class_bkt_right = 'punct-rs';

    // Хэш классов
    protected $classes_array = array();

    /**
     * Выполняем обработку
     * @param string $text
     * @return string
     */
    public function process($text) {

        $this->classes_array = array(
            self::CLASS_QUOTE_LEFT => $this->class_quote_left,
            self::CLASS_QUOTE_RIGHT => $this->class_quote_right,
            self::CLASS_BKT_LEFT => $this->class_bkt_left,
            self::CLASS_BKT_RIGHT => $this->class_bkt_right,
        );

        $lines = explode(PHP_EOL, $text);

        $words = array();
        $classes = array();
        foreach ($lines as $num=>$line){
            $words[$num] = explode(' ', $line);
            $classes[$num] = array();
        }

        foreach ($words as $line_num => $line){
            foreach ($line as $word_num => $word){

                $first_letter = mb_substr($word, 0, 1, 'utf-8');
                if (!isset ($classes[$line_num][$word_num]))
                    $classes[$line_num][$word_num] = array();

                if (in_array($first_letter, array('&laquo;', '«', '('))){
                    $quote = in_array($first_letter, array('&laquo;', '«'));
                    $classes[$line_num][$word_num][] = $quote ? self::CLASS_QUOTE_LEFT : self::CLASS_BKT_LEFT;
                    if ($word_num){
                        $classes[$line_num][$word_num-1][] = $quote ? self::CLASS_QUOTE_RIGHT : self::CLASS_BKT_RIGHT;
                    }
                }
            }
        }

        $text = '';
        foreach ($words as $line_num => $line){
            foreach ($line as $word_num => $word){
                if (!empty($classes[$line_num][$word_num])){
                    $words[$line_num][$word_num] = $this->wrapWord($words[$line_num][$word_num], $classes[$line_num][$word_num]);
                }
            }
            $text .= implode(' ', $words[$line_num]);
        }
        return $text;
    }

    /**
     * Обварачиваем слова
     * @param string $word
     * @param array $classes
     * @return string
     */
    protected function wrapWord($word, Array $classes){
        $html = '<span class="';
        $cls = array();
        foreach ($classes as $class){
            $cls[] = $this->classes_array[$class];
        }
        $html = $html . implode(' ', $cls);
        $html = $html . '">' . $word . '</span>';
        return $html;
    }
}