解析Boost program_options中配置文件的未注册选项? [英] Parsing unregistered options for config files in Boost program_options?

问题描述

使用命令行选项，我可以执行以下操作:

With command line options, I can do the following:

po::variables_map vm;
auto parsedOptions = po::command_line_parser(argc, argv).options(optionsDescription1).allow_unregistered().run();
po::store(parsedOptions, vm);
po::notify(vm);

auto unregistered = po::collect_unrecognized(parsedOptions.options, po::include_positional);
po::variables_map vm2;
auto parsedOptions2 = po::command_line_parser(unregistered).options(optionsDescription2).run();
po::store(parsedOptions2, vm2);
po::notify(vm2);

这很好用，因为collect_unregistered()收集的命令行标记与在命令行中显示的完全相同.但是，它不适用于配置文件.我可以解析一个允许未注册选项的配置文件，但是当我收集未注册选项时，会得到无法使用的结果.

This works fine, because collect_unregistered() collects the command line tokens exactly as it appeared in the command line. However, it doesn't work for config files. I can parse a config file allowing unregistered options, but when I collect the unregistered options, I get a result that I cannot use.

po::variables_map vm;
auto parsedOptions = po::parse_config_file<char>(filename, optionsDescription1, true);
po::store(parsedOptions, vm);
po::notify(vm);
auto unregistered = po::collect_unrecognized(parsedOptions.options, po::include_positional);

在这种情况下，我得到列出的选项的名称和值.例如，如果配置文件包含以下选项:

In this case I get the names and values of the options listed. For example, if the config file contained the following options:

unregistered_option1=value1
unregistered_option2=value2

然后我在字符串向量unregistered中获得值unregistered_option1，value1，unregistered_option2，value2. Boost的解析器无法对此格式做任何有用的事情.有什么方法可以解析此列表(即使用不同的options_description解析第一个options_description无法识别的所有选项)?当然，我可以使用设置了allow_unregistered的第二个options_description再次解析该文件，但是然后我无法检查两个描述都不知道的选项.

Then I get the values unregistered_option1, value1, unregistered_option2, value2 in the string vector unregistered. Boost's parser cannot do anything useful with this format. Is there any way to parse this list (i.e. parse all the options that were unrecognized by the first options_description with a different options_description)? Of course I can just parse the file again with the second options_description with allow_unregistered set, but then I can't check for options unknown to both descriptions.

推荐答案

您不必依赖collect_unrecognized()返回值的不完善之处，因此，您始终可以自己检测，处理和重构选项. parse_config_file()保持与未知选项的观察关系:

You don't have to rely on the imperfections of collect_unrecognized() return value, you can always detect, handle and reconstruct the options yourself, as the result of parse_config_file() keeps the observed relationship for the unknown options:

auto parsed_options = parse_config_file(ifs, config_file_options, true);
store(parsed_options, vm);
...
for (const auto& o : parsed_options.options) {
    if (vm.find(o.string_key) == vm.end()) {
        // an unknown option
        cout << o.string_key << "=" << o.value << "\n";
    }
}

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