我正在使用 Boost program_options 以标准方式解析配置文件,如
program_options 的 multiple_sources.cpp 示例文件所示。
ifstream ini_file("config.ini");
po::store(po::parse_config_file(ini_file, desc, true), vm);
po::notify(vm);
然而,config.ini 文件有空的键=值对,例如:
key1=value1
key2=value2
key3=
key4=
key5=value5
尝试读取此文件会导致 Boost 错误:
boost::program_options::invalid_option_value
boost::program_options 中是否有任何机制来读取这些带有空整的配置文件?
任何帮助将非常感激。
我正在编辑此问题,因为问题尚未解决。我将仅引用 Boost (1.53) 中的示例。
这是完整的 multiple_sources.cpp 文件:
#include <boost/program_options.hpp>
namespace po = boost::program_options;
#include <iostream>
#include <fstream>
#include <iterator>
using namespace std;
// A helper function to simplify the main part.
template<class T>
ostream& operator<<(ostream& os, const vector<T>& v)
{
copy(v.begin(), v.end(), ostream_iterator<T>(os, " "));
return os;
}
int main(int ac, char* av[])
{
try {
int opt;
string config_file;
// Declare a group of options that will be
// allowed only on command line
po::options_description generic("Generic options");
generic.add_options()
("version,v", "print version string")
("help", "produce help message")
//("optimization","optimization level")
("config,c", po::value<string>(&config_file)->default_value("multiple_sources.cfg"),
"name of a file of a configuration.")
;
// Declare a group of options that will be
// allowed both on command line and in
// config file
po::options_description config("Configuration");
config.add_options()
("optimization", po::value<int>(&opt)->default_value(10),
"optimization level")
("include-path,I", po::value< vector<string> >()->composing(),
"include path")
;
// Hidden options, will be allowed both on command line and
// in config file, but will not be shown to the user.
po::options_description hidden("Hidden options");
hidden.add_options()
("input-file", po::value< vector<string> >(), "input file")
;
po::options_description cmdline_options;
cmdline_options.add(generic).add(config).add(hidden);
po::options_description config_file_options;
config_file_options.add(config).add(hidden);
po::options_description visible("Allowed options");
visible.add(generic).add(config);
po::positional_options_description p;
p.add("input-file", -1);
po::variables_map vm;
store(po::command_line_parser(ac, av).
options(cmdline_options).positional(p).run(), vm);
notify(vm);
ifstream ifs(config_file.c_str());
if (!ifs)
{
cout << "can not open config file: " << config_file << "\n";
return 0;
}
else
{
store(parse_config_file(ifs, config_file_options), vm);
notify(vm);
}
if (vm.count("help")) {
cout << visible << "\n";
return 0;
}
if (vm.count("version")) {
cout << "Multiple sources example, version 1.0\n";
return 0;
}
if (vm.count("include-path"))
{
cout << "Include paths are: "
<< vm["include-path"].as< vector<string> >() << "\n";
}
if (vm.count("input-file"))
{
cout << "Input files are: "
<< vm["input-file"].as< vector<string> >() << "\n";
}
cout << "Optimization level is " << opt << "\n";
}
catch(exception& e)
{
cout << e.what() << "\n";
return 1;
}
return 0;
}
而对应的配置文件(multiple_sources.cfg)为:
#
# Comment out this line to use hard-coded default value of 10
#
optimization = 1
include-path = /opt
如果现在将此文件修改为:
#
# Comment out this line to use hard-coded default value of 10
#
optimization =
include-path = /opt
抛出以下错误消息:
the argument for option 'optimization' is invalid
具有验证重载等的建议解决方案似乎不必要地复杂,特别是因为可能必须为每种数据类型编写验证函数,并结合识别“\ n”其他空白的可能性。
有什么建议么?感谢大家抽出宝贵的时间。
按照 Aditya 的建议,我替换了以下行:
("optimization", po::value<int>(&opt)->default_value(10),
"optimization level")
具有以下内容:
("optimization", po::value<int>(&opt)->zero_tokens(),
"optimization level")
和 :
("optimization", po::value<int>(&opt)->implicit_value(10),
"optimization level")
他们都没有阅读空白选项。Boost 示例程序“parser_test.cpp”通过将键值对读入向量中绕过了 zero_tokens() 或implicit_value() 的使用,如下所示:
void test_config_file(const char* config_file)
{
options_description desc;
desc.add_options()
("gv1", new untyped_value)
("gv2", new untyped_value)
("empty_value", new untyped_value)
("plug*", new untyped_value)
("m1.v1", new untyped_value)
("m1.v2", new untyped_value)
("b", bool_switch())
;
const char content1[] =
" gv1 = 0#asd\n"
"empty_value = \n"
"plug3 = 7\n"
"b = true\n"
"[m1]\n"
"v1 = 1\n"
"\n"
"v2 = 2\n"
;
vector<option> a2 = parse_config_file<char>(config_file, desc).options;
BOOST_REQUIRE(a2.size() == 6);
check_value(a2[0], "gv1", "0");
check_value(a2[1], "empty_value", "");
check_value(a2[2], "plug3", "7");
check_value(a2[3], "b", "true");
check_value(a2[4], "m1.v1", "1");
check_value(a2[5], "m1.v2", "2");
}