Boost Spirit 嵌套组件

问题描述

我正在尝试使用 Spirit Qi 解析以下消息：

"A/B AND C/D","A/B","A/B AND C/D AND E/F"

我能够解析“A/B”，但无法获得其他字符串的正确结果。

我尝试了以下代码：

qi::rule<It,AstNodeVector()> entries;
qi::rule<It,AstNodeVector()> lists;
qi::rule<It,std::string()> element;

this->entries= *(this->lists % " AND ");
this->lists= this->element >> '/' >> this->element;
this->element = qi::char_("A-Z");

我的语法有什么问题？

解决方法

看来您没有跳过空格。也许这是一个概念上的问题（参见 Boost spirit skipper issues）。

无论如何，它确实解析：

Live On Coliru

#include <boost/spirit/include/qi.hpp>
#include <iomanip>
namespace qi = boost::spirit::qi;

using AstNodeVector = std::vector<std::string>;

template <typename It>
struct P : qi::grammar<It,AstNodeVector()> {
    P() : P::base_type(entries) {
        entries = *(lists % " AND ");
        lists   = element >> '/' >> element;
        element = qi::char_("A-Z");
    }
  private:
    qi::rule<It,AstNodeVector()> entries;
    qi::rule<It,AstNodeVector()> lists;
    qi::rule<It,std::string()> element;
};

int main() {
    using It = std::string::const_iterator;
    P<It> const p {};

    for (std::string const input: {
        "A/B AND C/D","A/B","A/B AND C/D AND E/F",})
    {
        It f = begin(input),l = end(input);
        AstNodeVector results;
        if (phrase_parse(f,l,p,qi::space,results)) {
            std::cout << "Success: " << std::quoted(input) << "\n";
            for (auto& el : results) {
                std::cout << " -- " << std::quoted(el) << "\n";
            }
        } else {
            std::cout << "FAIL: " << std::quoted(input) << "\n";
        }

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

印刷品

Success: "A/B AND C/D"
 -- "A"
 -- "B"
 -- "C"
 -- "D"
Success: "A/B"
 -- "A"
 -- "B"
Success: "A/B AND C/D AND E/F"
 -- "A"
 -- "B"
 -- "C"
 -- "D"
 -- "E"
 -- "F"

也许您应该包含自包含的代码，或者详细说明问题究竟出在哪里。