protected function getEvaluatorByMatchType($matchType)
    {
        $evaluatorsByMatchType = array();
        $evaluatorsByMatchType[self::EXACT_MATCH_TYPE] = 'exactEvaluator';
        $evaluatorsByMatchType[self::EXISTS_MATCH_TYPE] = 'existsEvaluator';
        $evaluatorsByMatchType[self::GREATER_THAN_MATCH_TYPE] = 'greaterThanEvaluator';
        $evaluatorsByMatchType[self::LESS_THAN_MATCH_TYPE] = 'lessThanEvaluator';
        $evaluatorsByMatchType[self::SUBSTRING_MATCH_TYPE] = 'substringEvaluator';

        return $evaluatorsByMatchType[$matchType];
    }