Boost.PFR

这是一个 C++14 库，用于非常基础的反射，它允许您通过索引访问结构体元素，并为用户定义的类型提供其他类似 std::tuple 的方法，而无需任何宏或样板代码。

Boost.PFR 是 Boost C++ Libraries 的一部分。但是，Boost.PFR 是一个纯头文件库，不依赖于 Boost。您可以直接将 GitHub 中“include”文件夹的内容复制到您的项目中，该库就可以正常工作。

有关不带 boost:: 命名空间版本的库，请参阅 PFR。

测试结果

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最新的开发者文档

激励示例 #0

#include <iostream>
#include <fstream>
#include <string>

#include "boost/pfr.hpp"

struct some_person {
  std::string name;
  unsigned birth_year;
};

int main(int argc, const char* argv[]) {
  some_person val{"Edgar Allan Poe", 1809};

  std::cout << boost::pfr::get<0>(val)                // No macro!
      << " was born in " << boost::pfr::get<1>(val);  // Works with any aggregate initializables!

  if (argc > 1) {
    std::ofstream ofs(argv[1]);
    ofs << boost::pfr::io(val);                       // File now contains: {"Edgar Allan Poe", 1809}
  }
}

输出

Edgar Allan Poe was born in 1809

运行上述示例

激励示例 #1

#include <iostream>
#include "boost/pfr.hpp"

struct my_struct { // no ostream operator defined!
    int i;
    char c;
    double d;
};

int main() {
    my_struct s{100, 'H', 3.141593};
    std::cout << "my_struct has " << boost::pfr::tuple_size<my_struct>::value
        << " fields: " << boost::pfr::io(s) << "\n";
}

输出

my_struct has 3 fields: {100, H, 3.14159}

激励示例 #2

#include <iostream>
#include "boost/pfr.hpp"

struct my_struct { // no ostream operator defined!
    std::string s;
    int i;
};

int main() {
    my_struct s{{"Das ist fantastisch!"}, 100};
    std::cout << "my_struct has " << boost::pfr::tuple_size<my_struct>::value
        << " fields: " << boost::pfr::io(s) << "\n";
}

输出

my_struct has 2 fields: {"Das ist fantastisch!", 100}

激励示例 #3

#include <iostream>
#include <string>

#include <boost/config/warning_disable.hpp>
#include <boost/spirit/home/x3.hpp>
#include <boost/fusion/include/adapt_boost_pfr.hpp>

#include "boost/pfr/io.hpp"

namespace x3 = boost::spirit::x3;

struct ast_employee { // No BOOST_FUSION_ADAPT_STRUCT defined
    int age;
    std::string forename;
    std::string surname;
    double salary;
};

auto const quoted_string = x3::lexeme['"' >> +(x3::ascii::char_ - '"') >> '"'];

x3::rule<class employee, ast_employee> const employee = "employee";
auto const employee_def =
    x3::lit("employee")
    >> '{'
    >>  x3::int_ >> ','
    >>  quoted_string >> ','
    >>  quoted_string >> ','
    >>  x3::double_
    >>  '}'
    ;
BOOST_SPIRIT_DEFINE(employee);

int main() {
    std::string str = R"(employee{34, "Chip", "Douglas", 2500.00})";
    ast_employee emp;
    x3::phrase_parse(str.begin(),
                     str.end(),
                     employee,
                     x3::ascii::space,
                     emp);
    std::cout << boost::pfr::io(emp) << std::endl;
}

输出

(34 Chip Douglas 2500)

要求和限制

请参阅文档.

License

根据 Boost Software License, Version 1.0 分发。