Question

我有一个有公共ctor和一些add（）方法的类：

class object
{
    object() {}
    template <typename>
    void add(T&& val) { // some adding here}
}

我面临的主要问题是如何采用spirit.x3列表解析器来使用object :: add（）方法而不是std :: vector＆lt;＆gt; :: push_back？

我很容易通过简单的

实现我所需要的

x3 :: int_％＆＃39;，＆＃39;

解析器（live demo）使用以下代码：

#include <boost/spirit/home/x3.hpp>
#include <iostream>
#include <vector>

namespace x3 = boost::spirit::x3;

namespace parse_to_object
{
    struct object
    {
        using value_type = int;

        object() { std::cout << "object::object() - invoked" << std::endl; }
        void add(value_type val) { _data.push_back(val); }

        std::vector<value_type> _data;
    };

    const x3::rule<struct Test, object> r_ints("r_ints");
    const auto r_ints_def = x3::int_  % ',';
    BOOST_SPIRIT_DEFINE(r_ints);
}

namespace boost { namespace spirit { namespace x3 { namespace traits {        
template<>
struct push_back_container<parse_to_object::object>
{
    template<typename T>
    static bool call(parse_to_object::object& obj, T&& val)
    {
        obj.add(std::move(val));
        return true;
    }
};
}}}}

int main()
{
    const std::string text("1,2,3,4");

    auto begin = std::begin(text);
    const auto end = std::end(text);

    parse_to_object::object result;
    const auto ok = x3::phrase_parse(begin, end, parse_to_object::r_ints,    x3::space, result);

    std::cout << "ok = " << std::boolalpha << (ok && begin == end) << std::endl;
    std::copy(result._data.begin(), result._data.end(), std::ostream_iterator<int>(std::cout, " "));
    return 0;
}

但不幸的是，当我尝试更多的编译示例时，如

＆＃39; {＆＃39; ＆GT;＆GT; x3 :: int_＆gt;＆gt; ＆＃39;：＆＃39; ＆GT;＆GT; x3 :: int_＆gt;＆gt; ＆＃39;}＆＃39;）％＆＃39;，＆＃39;

我收到编译错误（live demo）：

/opt/wandbox/boost-1.67.0/clang-head/include/boost/spirit/home/x3/support/traits/container_traits.hpp:102:45：错误：没有命名的类型＆＃39; iterator＆＃39; in＆＃39; parse_to_object :: object＆＃39; ：mpl :: identity {};

有人可以协助使用spirit.x3特性，并举例说明如何使用自定义类代替std :: vector＆lt;＆gt;列表解析器？

Answer 1

最后，它失踪了包括：

<?php

$travels = array(
          '0' => array('Départ ' =>'Paris', 'Arrivée ' => 'Nantes', 'Heure de départ ' => '11:00', 'Heure d\'arrivée ' => '12:34', 'Chauffeur ' => 'Thomas'),
          '1' => array('Départ ' =>'Orléans', 'Arrivée ' => 'Nantes', 'Heure de départ ' =>'05:15', 'Heure d\'arrivée ' => '09:32', 'Chauffeur ' =>'Mathieu'),
          '2' => array('Départ ' =>'Dublin', 'Arrivée ' => 'Tours', 'Heure de départ ' =>'07:23', 'Heure d\'arrivée ' => '08:50', 'Chauffeur ' =>'Nathanaël'),
          '3' => array('Départ ' =>'Paris', 'Arrivée ' => 'Orléans', 'Heure de départ ' =>'03:00', 'Heure d\'arrivée ' => '05:26', 'Chauffeur ' => 'Clément'),
          '4' => array('Départ ' =>'Paris', 'Arrivée ' => 'Nice', 'Heure de départ ' => '10:00', 'Heure d\'arrivée ' => '12:09', 'Chauffeur ' => 'Audrey'),
          '5' => array('Départ ' =>'Nice', 'Arrivée ' => 'Nantes', 'Heure de départ ' => '10:40', 'Heure d\'arrivée ' =>'13:00', 'Chauffeur ' =>'Pollux'),
          '6' => array('Départ ' =>'Nice', 'Arrivée ' => 'Tours', 'Heure de départ ' => '11:00', 'Heure d\'arrivée ' => '16:10', 'Chauffeur ' =>'Edouard'),
          '7' => array('Départ ' =>'Tours', 'Arrivée ' => 'Amboise', 'Heure de départ ' => '16:00', 'Heure d\'arrivée ' => '18:40', 'Chauffeur ' =>'Priscilla'),
          '8' => array('Départ ' =>'Nice', 'Arrivée ' => 'Nantes', 'Heure de départ ' => '12:00', 'Heure d\'arrivée ' =>'16:00', 'Chauffeur ' =>'Charlotte')
          );

$selected = 'Paris';

function get_destination($travel) {
    global $selected;

    return $travel["Départ "] === $selected;
}

print_r(array_filter($travels, 'get_destination'));

#include <boost/fusion/adapted/std_pair.hpp>默认情况下不适用。

附注：std::pair应为std::move，其中包含＆＃34;通用引用＆＃34; （或完美转发）

<强> Live On Coliru

std::forward<T>

打印

#define BOOST_SPIRIT_X3_DEBUG

#include <boost/fusion/adapted/std_pair.hpp>
#include <boost/spirit/home/x3.hpp>
#include <iostream>
#include <vector>

namespace x3 = boost::spirit::x3;

namespace parse_to_object
{
    struct object
    {
        using value_type = std::pair<int,int>;

        object() { std::cout << "object::object() - invoked" << std::endl; }
        void add(value_type val) { _data.push_back(std::move(val)); }

        std::vector<std::pair<int,int>> _data;
    };

    const x3::rule<struct Test, object> r_ints("r_ints");
    const auto r_ints_def = ('{' >> x3::int_ >> ':' >> x3::int_ >> '}') % ',';
    BOOST_SPIRIT_DEFINE(r_ints)
}

namespace boost { namespace spirit { namespace x3 { namespace traits {

    template<> struct push_back_container<parse_to_object::object>
    {
        template<typename T>
        static bool call(parse_to_object::object& obj, T&& val)
        {
            obj.add(std::forward<T>(val));
            return true;
        }
    };

}}}}

int main()
{
    const std::string text("{1:2},{3:4}");

    auto begin = std::begin(text), end = std::end(text);

    parse_to_object::object result;
    auto ok = phrase_parse(begin, end, parse_to_object::r_ints >> x3::eoi, x3::space, result);

    std::cout << "ok = " << std::boolalpha << ok << "\n";
    for (auto& p : result._data)
        std::cout << "{" << p.first << ", " << p.second << "} ";
    std::cout << "\n";
}

Spirit.X3：使用带有列表解析器的push_back_container特征

1 个答案: