c++ - 无法使用 boost spirit 将值添加到 vector

Question

我想使用 boost spirit 解析以下字符串:

"{"DeliverNr":7424,"fruits":[["apple","banana","orange", "raspberry"]]}"

但我只想将三个初熟的果实放入 vector 中。

我有以下输出:

it: { , dist: 0

谁能告诉我我做错了什么？

#define BOOST_SPIRIT_USE_PHOENIX_V3

#include <boost/spirit/include/phoenix_core.hpp>
#include <boost/spirit/include/phoenix_operator.hpp>
#include <boost/spirit/include/qi.hpp>
#include <boost/config/warning_disable.hpp>
#include <boost/spirit/include/qi.hpp>
#include <boost/spirit/include/phoenix_core.hpp>
#include <boost/spirit/include/phoenix_operator.hpp>
#include <boost/spirit/include/phoenix_fusion.hpp>
#include <boost/spirit/include/phoenix_stl.hpp>
#include <boost/fusion/include/adapt_struct.hpp>
#include <boost/variant/recursive_variant.hpp>
#include <boost/foreach.hpp>
#include <iostream>
#include <vector>

struct SomeStructF
{
    std::string str1, str2, str3;
};

    using namespace boost::spirit;

    qi::rule<std::string::iterator> startRule;
    qi::rule<std::string::iterator> endRule;
    qi::rule<std::string::iterator, std::string()> stringRule;
    qi::rule<std::string::iterator, SomeStructF()> valueRule;
    qi::rule<std::string::iterator, std::vector<SomeStructF>()> valuesRule;
    char const QUOTATION_MARK{ '"' };
    char const OPEN_SQUARE_BRACKET{ '[' };

    startRule =
            +(qi::char_ - qi::char_(OPEN_SQUARE_BRACKET))
        >> qi::char_(OPEN_SQUARE_BRACKET);

    endRule = +qi::char_;

    stringRule =
            QUOTATION_MARK
        >> *(qi::char_ - QUOTATION_MARK)
        >> QUOTATION_MARK;

    valueRule =
            OPEN_SQUARE_BRACKET
        >> stringRule
        >> stringRule
        >> stringRule;

    valuesRule %=
            startRule
        >> valueRule
        >> endRule;

    std::vector<SomeStructF> res;
    auto it = data.begin();

    if (qi::parse(it, data.end(), valuesRule, res))
    {
        std::cout << "PARSE succeded" << std::endl;
    }
    std::cout << "it: " << *it << " , dist: " <<  std::distance(data.begin(), it) << std::endl;

    std::cout << "res size " << res.size() << std::endl;

BOOST_FUSION_ADAPT_STRUCT(
        parsers::SomeStructF,
        (std::string, str1)
        (std::string, str2)
        (std::string, str3)
)

Answer 1

我不是特别清楚你在问什么。正如您所指出的，在我看来很容易考虑逗号:

Live On Coliru

#define BOOST_SPIRIT_DEBUG
#include <iostream>
#include <vector>
#include <string>
#include <iterator>
#include <iomanip>
#include <boost/spirit/include/qi.hpp>
#include <boost/fusion/include/adapt_struct.hpp>

namespace qi = boost::spirit::qi;

struct SomeStructF {
    std::string str1, str2, str3;
};

BOOST_FUSION_ADAPT_STRUCT(
        SomeStructF,
        (std::string, str1)
        (std::string, str2)
        (std::string, str3)
)

int main()
{
    qi::rule<std::string::iterator> startRule;
    qi::rule<std::string::iterator> endRule;
    qi::rule<std::string::iterator, std::string()> stringRule;
    qi::rule<std::string::iterator, SomeStructF()> valueRule;
    qi::rule<std::string::iterator, SomeStructF()> valuesRule;
    char const QUOTATION_MARK{ '"' };
    char const OPEN_SQUARE_BRACKET{ '[' };

    startRule =
            +(qi::char_ - qi::char_(OPEN_SQUARE_BRACKET))
        >> qi::char_(OPEN_SQUARE_BRACKET);

    endRule = +qi::char_;

    stringRule =
            QUOTATION_MARK
        >> *(qi::char_ - QUOTATION_MARK)
        >> QUOTATION_MARK;

    valueRule =
            OPEN_SQUARE_BRACKET
        >> stringRule >> ','
        >> stringRule >> ','
        >> stringRule;

    valuesRule %=
            startRule
        >> valueRule
        >> endRule;
    BOOST_SPIRIT_DEBUG_NODES((startRule)(endRule)(stringRule)(valueRule)(valuesRule));

    std::string data = R"({"DeliverNr":7424,"fruits":
[["apple","banana","orange","raspberry"]]})";

    std::vector<SomeStructF> res;
    auto it = data.begin();

    if (qi::parse(it, data.end(), valuesRule, res))
    {
        std::cout << "PARSE succeded" << std::endl;
        std::cout << "res size " << res.size() << std::endl;

        for (auto& el : res) {
            std::cout << "el: {" << std::quoted(el.str1) << ","
                                 << std::quoted(el.str2) << ","
                                 << std::quoted(el.str3) << "}\n";
        }
    }
    else
    {
        std::cout << "Parse did not succeed\n";
    }

    if (it != data.end())
        std::cout << "Remaining unparsed: '" << std::string(it, data.end()) << "'\n";

}

打印

PARSE succeded
res size 1
el: {"apple","banana","orange"}

你的语法(也不是你的问题)显示了你想如何检测多个 SomeStructF 所以我真的不知道你想要什么。也许您想简化:

Live On Coliru

using It = std::string::const_iterator;
qi::rule<It, std::string()> quoted_ = '"' >> *~qi::char_('"') >> '"';
qi::rule<It, SomeStructF()/*, qi::space_type*/> value_ = quoted_ >> ',' >> quoted_ >> ',' >> quoted_;
using boost::spirit::repository::qi::seek;
BOOST_SPIRIT_DEBUG_NODES((quoted_)(value_));

std::string const data = R"({"DeliverNr":7424,"fruits":[["apple","banana","orange","raspberry"]]}
{"DeliverNr":7435,"botanics":[["pine","maple","oak","pernambucco"]]})";

std::vector<SomeStructF> res;
It it = data.begin();

if (qi::phrase_parse(it, data.end(), *seek["[[" >> value_], qi::space, res)) {
    for (auto& el : res) {
        std::cout << "el: {" << std::quoted(el.str1) << ","
                             << std::quoted(el.str2) << ","
                             << std::quoted(el.str3) << "}\n";
    }
} else {
    std::cout << "Parse did not succeed\n";
}

哪个打印

el: {"apple","banana","orange"}
el: {"pine","maple","oak"}
Remaining unparsed: ',"pernambucco"]]}'