c++ - 提神气递归

Question

我一定是错过了 boost::recursive_wrapper 的东西，我总是得到一个错误:

error: no matching function for call to 'boost::tuples::tuple, std::allocator >, client::compare_attr_op_t, std::basic_string, std::allocator >, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type, boost::tuples::null_type>::tuple(client::expression_value&)'

对于在语法中定义“表达式”的行:expression %= attribute_test | bool 表达式；

有什么想法吗？

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;
    };
}

Answer 1

我把所有的东西都扔了，从头开始，给了我这个很好的、有效的实现:

namespace client {

    enum compare_attr_op_t {
        cao_eq,
        cao_neq
    };

    enum boolean_op_t {
        bo_and,
        bo_or,
        bo_not
    };

    struct expression_value;
    struct or_op_value;
    struct and_expression_value;
    struct and_op_value;
    struct not_op_value;

    typedef boost::tuple<std::string, compare_attr_op_t, std::string> attribute_test_value;
    typedef boost::variant<attribute_test_value, boost::recursive_wrapper<expression_value>, boost::recursive_wrapper<not_op_value> > node_value;

    struct not_op_value {
        boolean_op_t operation;
        node_value rnode;
    };

    struct and_op_value {
        boolean_op_t operation;
        node_value rnode;
    };

    struct and_expression_value {
        node_value lnode;
        std::vector<and_op_value> ops;
    };

    struct or_op_value {
        boolean_op_t operation;
        and_expression_value rnode;
    };

    struct expression_value {
        and_expression_value lnode;
        std::vector<or_op_value> ops;
    };


}

BOOST_FUSION_ADAPT_STRUCT(
        client::not_op_value,
        (client::boolean_op_t, operation)
        (client::node_value, rnode)
)

BOOST_FUSION_ADAPT_STRUCT(
    client::and_expression_value,
    (client::node_value, lnode)
    (std::vector<client::and_op_value>, ops)
)

BOOST_FUSION_ADAPT_STRUCT(
    client::and_op_value,
    (client::boolean_op_t, operation)
    (client::node_value, rnode)
)

BOOST_FUSION_ADAPT_STRUCT(
    client::expression_value,
    (client::and_expression_value, lnode)
    (std::vector<client::or_op_value>, ops)
)

BOOST_FUSION_ADAPT_STRUCT(
    client::or_op_value,
    (client::boolean_op_t, operation)
    (client::and_expression_value, rnode)
)


namespace client {
    struct compare_attr_ : qi::symbols<char, compare_attr_op_t>
    {
        compare_attr_()
        {
            add
                ("="    , cao_eq)
                ("!="   , cao_neq)
            ;
        }

    } compare_attr;

    struct boolean_op_and_t : qi::symbols<char, boolean_op_t>
    {
        boolean_op_and_t()
        {
            add
                ("&"   , bo_and)
                ("and"   , bo_and)
            ;
        }

    } boolean_op_and;

    struct boolean_op_or_t : qi::symbols<char, boolean_op_t>
    {
        boolean_op_or_t()
        {
            add
                ("|"   , bo_or)
                ("or"   , bo_or)
            ;
        }

    } boolean_op_or;

    struct boolean_op_not_t : qi::symbols<char, boolean_op_t>
    {
        boolean_op_not_t()
        {
            add
                ("!"   , bo_not)
                ("not"   , bo_not)
            ;
        }

    } boolean_op_not;

    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;
            using ascii::no_case;

            expression %= and_expression >> *(no_case[boolean_op_or] >> and_expression);
            and_expression %= node >> *(no_case[boolean_op_and] >> node);
            node %= attribute_test | ('(' >> expression >> ')') | not_operation;
            not_operation %= no_case[boolean_op_not] >> node;
            attribute_test %= (attribute_name >> no_case[compare_attr] >> attribute_value);
            attribute_name %= alpha >> *char_("A-Za-z0-9_");
            attribute_value %= lexeme['"' > +(char_ - '"') > '"'];

        }

        qi::rule<Iterator, expression_value(), ascii::space_type> expression;
        qi::rule<Iterator, and_expression_value(), ascii::space_type> and_expression;
        qi::rule<Iterator, not_op_value(), ascii::space_type> not_operation;
        qi::rule<Iterator, node_value(), ascii::space_type> node;
        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;
    };
}