{

boost::char_separator<char> s(" ,()\t\n\r");

//boost::escaped_list_separator<char> s;

token_parser parser

( boost::make_token_iterator<std::string>(text.begin(), text.end(), s)

, boost::make_token_iterator<std::string>(text.end() , text.end(), s) );

while (parser.has_more_tokens())

{

// read function name

std::string func_name = parser.get<std::string>();

// look up function

dictionary::const_iterator entry = map_invokers.find( func_name );

if (entry == map_invokers.end())

//throw std::runtime_error("unknown function: " + func_name);

throw NotAFunction(func_name);

// call the invoker which controls argument parsing

entry->second(parser);

}