public function buildProximityMatch($operator, $operands, &$params)
    {
        if (!isset($operands[0], $operands[1], $operands[2])) {
            throw new InvalidParamException("Operator '$operator' requires three operands.");
        }

        list($column, $value, $proximity) = $operands;

        return $this->buildMatchColumn($column) . ' ' . $this->buildMatchValue($value, $params) . '~' . (int) $proximity;
    }