Boost Spirit Parser 使用三个字符串的向量编译成一个结构,适应不工作

Boost Spirit Parser with a vector of three strings compiling into a struct, adapt not working

我是一名学生,需要使用 Boost-Library 用 C++ 编写解析器。

因此我在 QI 中写了一个语法,因为我需要解析成一个结构。到目前为止,一切都很好。

我会给你一些示例代码。我认为这比写下整个程序要容易。

说明: 所以首先我们获取一个 txt 文件并读取它,然后解析器遍历它,说 "Parsing is ok!" 并解析到结构中。我们的输出是控制台中的结构。

效果很好,现在来一些代码示例。在这里可以看到Boost Spirit QI中的语法:

subject %= lexeme[lit("Fach: ") >> +(char_("a-zA-Z"))   >> lit("\n")]; //works!

        dozent %= lexeme[lit("Dozent: ") >> +(char_("a-zA-Z")) >> lit("\n")];

        date %= lexeme[lit("Datum: ") >> digit >> digit >> lit("-") >> digit >> digit >> lit("-") >> digit >> digit >> digit >> digit >> lit("\n")];

        count %= lexeme[lit("Anzahl: ") >> +digit >> lit("\n")];

        points %= lexeme[+digit >> lit("\t")];

        mark %= lexeme[digit >> lit("\n")];

        matnumber %= lexeme[(digit >> digit >> digit >> punct >> digit >> digit >> digit) >> lit("\t")];

        student %= matnumber >> points >> mark;

        start %=  subject >> dozent >> date >> count >> student;

这很好用,student 的规则带来了一个问题,即我们有一个包含三个部分的元素。 Matnumber、Points 和 mark。你可以想象我的意思,这里是我们尝试解析的 TXT 文件:

Subject: Physics
Dozent: Wayne
Datum: 20-10-2014
Anzahl: 20
729.888 33  5
185.363 35  5

最后两行是rule student。而在 txt 文件中,我们不止这两行。

我们可以把这些行当作 "student" 我们用 typedef 在我们的结构中写了一个向量:

typedef boost::fusion::vector<string, string, string> student_t;

然后我们将在我们的结构中使用它:

struct klausur
{
    string str_subject;
    string str_dozent;
    string str_date;
    string count;
    string matr_nr;
    string points;
    string mark;
    string ende;
    student_t student;

    void ToString()
    {
        cout << "Struct.Fach: " << str_subject << endl;
        cout << "Struct.Dozent: " << str_dozent << endl;
        cout << "Struct.Datum: " << str_date << endl;
        cout << "Struct.Anzahl: " << count << endl;
        cout << "Struct.Mat_Nr: " << matr_nr << endl;
        cout << "Struct.Punkte: " << points << endl;
        cout << "Struct.Note: " << mark << endl;
        cout << "Struct.Student<0>: " << vec::at_c<0>(student); 
        cout << "Struct.Student<1>: " << vec::at_c<1>(student);
        cout << "Struct.Student<2>: " << vec::at_c<2>(student);

    }
};

然后我们有这样的 BOOST_ADAPT_STRUCT:

BOOST_FUSION_ADAPT_STRUCT(
client::klausur,
(string, str_subject)
(string, str_dozent)
(string, str_date)
(string, count)
(string, matr_nr)
(string, points)
(string, mark)
(student_t, student)

)

你看我们下面有typedef。

然后我们在语法中有我们的规则。

    qi::rule<Iterator, string(), ascii::space_type> subject;
    qi::rule<Iterator, string(), ascii::space_type> dozent;
    qi::rule<Iterator, string(), ascii::space_type> date;
    qi::rule<Iterator, string(), ascii::space_type> count;
    qi::rule<Iterator, string(), ascii::space_type> matnumber;
    qi::rule<Iterator, string(), ascii::space_type> points;
    qi::rule<Iterator, string(), ascii::space_type> mark;
    qi::rule<Iterator, boost::fusion::vector<boost::fusion::vector<std::string, std::string, std::string> >()> student; 

还有我们项目的最终问题……

我们不知道 qi:rule 需要哪种数据类型 BOOST_ADAPT... 可以正常工作。所有其他点都是字符串,但不知道如何实现我们创建的自己的向量。

所有其他规则都工作正常,稍后在结构中,只是向量出了问题。

有人对此有想法吗?如果您需要,我可以上传更多文件和代码片段,但我仍然认为这可能只是我看不到的一个小问题。我四处寻找许多提升主题,但没有找到合适的东西。

我必须补充一点,我只是一个初学者,所以也许我没有正确解释所有内容......是的。希望你能理解。我的英语也不是最好的...

提前感谢您的帮助。

威廉

Spirit 是一个解析器生成器。你似乎并没有真正解析任何东西(你只是 "extract" 字符序列,这更像是标记化)。

我会这样做:

  • 使用正确的数据类型
  • 使用blank跳过(不包括eol
  • eol 期望放在正确的位置
  • 把词位放在正确的位置
  • 使date_t成为自己的类型
  • 使student_t成为自己的类型
  • FIX 使用 std::vector<student_t>() 而不是 ~ fusion::vector<student_t>() 的规则(这是一个错误)
  • 使用operator<<打印
  • 使用repeat(n) [ student >> eol ]解析期望的学生行数
  • 使用qi::locals实际将预期的学生人数传递给repeat()

Live On Coliru

#define BOOST_SPIRIT_DEBUG
#include <boost/spirit/include/qi.hpp>
#include <boost/spirit/include/phoenix.hpp>
#include <boost/fusion/adapted/struct.hpp>
#include <iostream>
#include <iomanip>

namespace qi = boost::spirit::qi;
namespace vec = boost::fusion;

struct student_t {
    std::string matr_nr;
    unsigned    points;
    int         mark;
};

struct date_t {
    unsigned dd, mm, yyyy;

    friend std::ostream& operator<<(std::ostream& os, date_t const& d) {
        std::ostream local(os.rdbuf());
        local << std::setw(2) << std::setfill('0') << d.dd <<
            "-" << std::setw(2) << std::setfill('0') << d.mm <<
            "-" << std::setw(4) << std::setfill('0') << d.yyyy;
        return os;
    }
};

BOOST_FUSION_ADAPT_STRUCT(student_t,
        (std::string,matr_nr)(unsigned,points)(int,mark))
BOOST_FUSION_ADAPT_STRUCT(date_t,
        (unsigned,dd)(unsigned,mm)(unsigned,yyyy))

struct klausur {
    std::string str_subject;
    std::string str_dozent;
    date_t date;

    unsigned count;
    std::vector<student_t>   students;

    friend std::ostream& operator<<(std::ostream& os, klausur const& k)
    {
        os << "Fach: "   << k.str_subject << '\n';
        os << "Dozent: " << k.str_dozent  << '\n';
        os << "Datum: "  << k.date        << '\n';
        os << "Anzahl: " << k.count       << '\n';
        for (auto& s : k.students) {
            os << "Mat_Nr: " << s.matr_nr << '\n';
            os << "Punkte: " << s.points  << '\n';
            os << "Note: "   << s.mark    << '\n';
        }
        return os;
    }
};

BOOST_FUSION_ADAPT_STRUCT(klausur,
        (std::string                     , str_subject)
        (std::string                     , str_dozent)
        (date_t                          , date)
        (unsigned                        , count)
        (std::vector<student_t>          , students)
    )

template <typename Iterator, typename Skipper = qi::ascii::blank_type>
struct grammar : qi::grammar<Iterator, klausur(), Skipper> {
    grammar() : grammar::base_type(start) {
        using namespace qi;
        subject   = "Fach:"   >> lexeme [ +~char_('\n') ] >> eol;
        dozent    = "Dozent:" >> lexeme [ +~char_('\n') ] >> eol;
        date      = "Datum:"  >> lexeme [uint_ >> '-' >> uint_ >> '-' >> uint_] >> eol;
        count     = "Anzahl:" >> uint_ >> eol;
        points    = uint_;
        mark      = int_parser<int, 10, 1, 1>(); // single base-10 digit

        // no clue about this format; what is it? Just a real number?
        matnumber = lexeme[digit >> digit >> digit >> punct >> digit >> digit >> digit];

        student   = matnumber >> points >> mark;

        _a_type expected;
        klausur_ %= subject
                 >> dozent
                 >> date
                 >> count            [ expected = _1 ]
                 >> repeat(expected) [ student >> (eol|eoi) ]
                 ;

        start     = klausur_;

        BOOST_SPIRIT_DEBUG_NODES((start)(klausur_)(student)(matnumber)(mark)(points)(count)(date)(dozent)(subject))
    }

  private:
    qi::rule<Iterator, klausur(), Skipper> start;
    qi::rule<Iterator, klausur(), Skipper, qi::locals<unsigned> > klausur_;

    qi::rule<Iterator, std::string()    , Skipper> subject;
    qi::rule<Iterator, std::string()    , Skipper> dozent;
    qi::rule<Iterator, date_t(),          Skipper> date;
    qi::rule<Iterator, unsigned()       , Skipper> count;
    qi::rule<Iterator, std::string()    , Skipper> matnumber;
    qi::rule<Iterator, unsigned()       , Skipper> points;
    qi::rule<Iterator, int()            , Skipper> mark;
    qi::rule<Iterator, student_t()      , Skipper> student;
};

int main() {
    using It = std::string::const_iterator;
    std::string const input =
R"(Fach: Physics
Dozent: Wayne
Datum: 20-10-2014
Anzahl: 2
729.888 33  5
185.363 35  5)";

    It f = input.begin(), l = input.end();

    grammar<It> g;
    klausur k;
    bool ok = qi::phrase_parse(f, l, g, qi::ascii::blank, k);

    if (ok) {
        std::cout << "Parse success\n";
        std::cout << k;
    } else {
        std::cout << "Parse failed\n";
    }

    if (f!=l) {
        std::cout << "Remaining input: '" << std::string(f,l) << "'\n";
    }
}

输出:

Parse success
Fach: Physics
Dozent: Wayne
Datum: 20-10-2014
Anzahl: 2
Mat_Nr: 729.888
Punkte: 33
Note: 5
Mat_Nr: 185.363
Punkte: 35
Note: 5

以及72行调试输出:

<start>
  <try>Fach: Physics\nDozent</try>
  <klausur_>
    <try>Fach: Physics\nDozent</try>
    <subject>
      <try>Fach: Physics\nDozent</try>
      <success>Dozent: Wayne\nDatum:</success>
      <attributes>[[P, h, y, s, i, c, s]]</attributes>
    </subject>
    <dozent>
      <try>Dozent: Wayne\nDatum:</try>
      <success>Datum: 20-10-2014\nAn</success>
      <attributes>[[W, a, y, n, e]]</attributes>
    </dozent>
    <date>
      <try>Datum: 20-10-2014\nAn</try>
      <success>Anzahl: 2\n729.888 33</success>
      <attributes>[[20, 10, 2014]]</attributes>
    </date>
    <count>
      <try>Anzahl: 2\n729.888 33</try>
      <success>729.888 33  5\n185.36</success>
      <attributes>[2]</attributes>
    </count>
    <student>
      <try>729.888 33  5\n185.36</try>
      <matnumber>
        <try>729.888 33  5\n185.36</try>
        <success> 33  5\n185.363 35  5</success>
        <attributes>[[7, 2, 9, ., 8, 8, 8]]</attributes>
      </matnumber>
      <points>
        <try> 33  5\n185.363 35  5</try>
        <success>  5\n185.363 35  5</success>
        <attributes>[33]</attributes>
      </points>
      <mark>
        <try>  5\n185.363 35  5</try>
        <success>\n185.363 35  5</success>
        <attributes>[5]</attributes>
      </mark>
      <success>\n185.363 35  5</success>
      <attributes>[[[7, 2, 9, ., 8, 8, 8], 33, 5]]</attributes>
    </student>
    <student>
      <try>185.363 35  5</try>
      <matnumber>
        <try>185.363 35  5</try>
        <success> 35  5</success>
        <attributes>[[1, 8, 5, ., 3, 6, 3]]</attributes>
      </matnumber>
      <points>
        <try> 35  5</try>
        <success>  5</success>
        <attributes>[35]</attributes>
      </points>
      <mark>
        <try>  5</try>
        <success></success>
        <attributes>[5]</attributes>
      </mark>
      <success></success>
      <attributes>[[[1, 8, 5, ., 3, 6, 3], 35, 5]]</attributes>
    </student>
    <success></success>
    <attributes>[[[P, h, y, s, i, c, s], [W, a, y, n, e], [20, 10, 2014], 2, [[[7, 2, 9, ., 8, 8, 8], 33, 5], [[1, 8, 5, ., 3, 6, 3], 35, 5]]]]</attributes><locals>(2)</locals>
  </klausur_>
  <success></success>
  <attributes>[[[P, h, y, s, i, c, s], [W, a, y, n, e], [20, 10, 2014], 2, [[[7, 2, 9, ., 8, 8, 8], 33, 5], [[1, 8, 5, ., 3, 6, 3], 35, 5]]]]</attributes>
</start>