c++ - 如何使用 boost::progam_option 和 boost::command_line_Parser 验证文件扩展名

Question

我正在编写一个使用 Boost 的程序选项库的程序，我无法使用 boost::program 选项验证文件扩展名:

 po::options_description desc("Allowed options");
    desc.add_options()
        ("help", "produce help message")
        ("diff,d", po::value< std::string >(),"Specify the .xyz file, name of the .xyz to create")**.xyz file I want to validate,while givin input as comman line **
    ;

    po::variables_map vm;
    po::store(po::parse_command_line(ac, av, desc), vm);
    po::notify(vm);

Answer 1

好的，你需要实现validate

您可以使用标签类型，这样您就可以通过Argument Dependent Lookup 关联您的validate :

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#include <boost/program_options.hpp>
#include <boost/algorithm/string.hpp>
#include <vector>
#include <iostream>

namespace tag {
    struct xyz_file {};

    bool validate(boost::any& v, std::vector<std::string> const& ss, xyz_file*, int) {
        if (ss.size() == 1 && boost::algorithm::iends_with(ss.front(), ".xyz"))
        {
            v = ss.front();
            return true;
        }
        return false;
    }
}

namespace po = boost::program_options;

int main(int ac, char** av) {
    po::options_description desc("Allowed options");
    desc.add_options()
        ("diff,d", po::value<tag::xyz_file>(), "xyz files only")
        ;

    po::variables_map vm;

    po::store(po::parse_command_line(ac, av, desc), vm);
    po::notify(vm);

    if (!vm["diff"].empty())
        std::cout << "Parsed: " << vm["diff"].as<std::string>() << "\n";
    else
        std::cout << desc;
}