我一定错过了 boost::recursive_wrapper 的东西,我总是得到一个错误:
错误:没有匹配函数调用'boost::tuples::tuple, std::allocator >, client::compare_attr_op_t, std::basic_string, std::allocator >, boost::tuples::null_type, boost::元组::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type>::tuple(client ::表达式值&)'
对于在语法中定义“表达式”的行:expression %= attribute_test | boolean_expression;
任何想法?
namespace client {
enum compare_attr_op_t {
cao_eq,
cao_neq
};
enum boolean_op_t {
bo_and,
bo_or,
bo_not
};
struct expression_value;
typedef boost::tuple<std::string, compare_attr_op_t, std::string> attribute_test_value;
typedef boost::tuple< expression_value, boolean_op_t, expression_value > boolean_expression_value;
typedef boost::variant< attribute_test_value, boost::recursive_wrapper<boolean_expression_value> > sub_expression_value;
struct expression_value {
sub_expression_value value;
};
}
BOOST_FUSION_ADAPT_STRUCT(
client::expression_value,
(client::sub_expression_value, value)
)
namespace client {
struct compare_attr_ : qi::symbols<char, compare_attr_op_t>
{
compare_attr_()
{
add
("=" , cao_eq)
("!=" , cao_neq)
;
}
} compare_attr;
struct boolean_op_ : qi::symbols<char, boolean_op_t>
{
boolean_op_()
{
add
("&" , bo_and)
("|" , bo_or)
;
}
} boolean_op;
template <typename Iterator>
struct attribute_conditions : qi::grammar<Iterator, expression_value(), ascii::space_type>
{
attribute_conditions() : attribute_conditions::base_type(expression)
{
using qi::eps;
using qi::lit;
using qi::_val;
using qi::lexeme;
using qi::_1;
using qi::_2;
using qi::_3;
using ascii::char_;
using ascii::alnum;
using ascii::alpha;
expression %= attribute_test | boolean_expression;
boolean_expression %= expression >> boolean_op >> expression;
attribute_test %= (attribute_name >> compare_attr >> attribute_value)[std::cout << _1 << ' ' << _2 << ' ' << _3];
attribute_name %= alpha >> *alnum;
attribute_value %= lexeme['"' > +(char_ - '"') > '"'];
}
qi::rule<Iterator, expression_value(), ascii::space_type> expression;
qi::rule<Iterator, boolean_expression_value(), ascii::space_type> boolean_expression;
qi::rule<Iterator, attribute_test_value(), ascii::space_type> attribute_test;
qi::rule<Iterator, std::string(), ascii::space_type> attribute_name;
qi::rule<Iterator, std::string(), ascii::space_type> attribute_value;
};
}