class Selector

class Selector {
    
    /**
     * Selector groups
     *
     * @var Group[]
     */
    protected $groups = array();
    
    /**
     * Adds a new group
     *
     * @param Group $group Group
     *
     * @return $this
     */
    public function addGroup(Group $group) {
        $this->groups[] = $group;
        return $this;
    }
    
    /**
     * Executes the current selector on the given matches
     *
     * @param Matches $matches Matches
     *
     * @return Matches
     */
    public function exec(Matches $matches) {
        $retMatches = array();
        foreach ($this->groups as $group) {
            $clonedMatches = $matches->createClone();
            $group->exec($clonedMatches);
            $retMatches[] = $clonedMatches;
        }
        if (count($retMatches) > 1) {
            $retMatches[0]->merge(array_slice($retMatches, 1));
        }
        return $retMatches[0];
    }

}