Question

我尝试过使用boost语义动作。就我而言，boost::bind是最简单的解决方案。第一个例子运作良好;在这里，我在语义行为中只使用了一个参数。

#include <boost/config/warning_disable.hpp>
#include <boost/spirit/include/qi.hpp>
#include <boost/bind.hpp>
#include <iostream>
namespace qi = boost::spirit::qi;

// A plain function
void print(int const& i)
{
    std::cout << i << std::endl;
}

int main()
{
    using boost::spirit::qi::int_;
    using boost::spirit::qi::parse;

    char const *first = "{44}", *last = first + std::strlen(first);
    parse(first, last, '{' >> int_[boost::bind(&print, _1)] >> '}');

    return 0;
}

我试图扩展我的代码。在第二种情况下，我想将两个参数传递给bound函数，但编译器不会编译此代码。什么失败了？我没有找到任何例子。第二个代码在这里：

#include <boost/config/warning_disable.hpp>
#include <boost/spirit/include/qi.hpp>
#include <boost/bind.hpp>
#include <iostream>
namespace qi = boost::spirit::qi;

// A plain function
void print(int const& i1, int const& i2)
{
    std::cout << i1 << "," << i2 << std::endl;
}

int main()
{
    using boost::spirit::qi::int_;
    using boost::spirit::qi::parse;

    char const *first = "{44,55}", *last = first + std::strlen(first);
    parse(first, last, '{' >> (int_ >> "," >> int_)[boost::bind(&print, _1,_2)] >> '}');

    return 0;
}

Answer 1

您无法编译此代码，因为只有一个输入参数 - boost :: fusion :: vector＆lt; int，int＆gt; - 由（int_＆gt;＆gt;“，”＆gt;＆gt; int_）序列组成。试试这个

#include <boost/config/warning_disable.hpp>
#include <boost/spirit/include/qi.hpp>
#include <boost/bind.hpp>
#include <iostream>
namespace qi = boost::spirit::qi;

// A plain function
void print(boost::fusion::vector < int, int > arg_)
{
    std::cout << boost::fusion::at_c < 0 > (arg_) << "," << boost::fusion::at_c < 1 > (arg_) << std::endl;
}

int _tmain(int argc, _TCHAR* argv[])
{
    using boost::spirit::qi::int_;
    using boost::spirit::qi::parse;

    char const *first = "{44,55}", *last = first + std::strlen(first);
    parse(first, last, '{' >> (int_ >> "," >> int_)[boost::bind(&print, _1)] >> '}');

    return 0;
}

当我使用boost :: bind时，为什么不使用boost :: spirit :: qi语义动作使用两个参数？

1 个答案: