ceph/src/boost/libs/program_options/example/regex.cpp

   1 // Copyright Vladimir Prus 2002-2004.
   2 // Distributed under the Boost Software License, Version 1.0.
   3 // (See accompanying file LICENSE_1_0.txt
   4 // or copy at http://www.boost.org/LICENSE_1_0.txt)
   5
   6 // This example shows how a user-defined class can be parsed using
   7 // specific mechanism -- not the iostream operations used by default.
   8 //
   9 // A new class 'magic_number' is defined and the 'validate' method is overloaded
  10 // to validate the values of that class using Boost.Regex.
  11 // To test, run
  12 //
  13 //    regex -m 123-456
  14 //    regex -m 123-4567
  15 //
  16 // The first invocation should output:
  17 //
  18 //   The magic is "456"
  19 //
  20 // and the second invocation should issue an error message.
  21
  22 #include <boost/program_options.hpp>
  23 #include <boost/regex.hpp>
  24
  25 using namespace boost;
  26 using namespace boost::program_options;
  27
  28 #include <iostream>
  29 using namespace std;
  30
  31 /* Define a completely non-sensical class. */
  32 struct magic_number {
  33 public:
  34     magic_number(int n) : n(n) {}
  35     int n;
  36 };
  37
  38 /* Overload the 'validate' function for the user-defined class.
  39    It makes sure that value is of form XXX-XXX
  40    where X are digits and converts the second group to an integer.
  41    This has no practical meaning, meant only to show how
  42    regex can be used to validate values.
  43 */
  44 void validate(boost::any& v,
  45               const std::vector<std::string>& values,
  46               magic_number*, int)
  47 {
  48     static regex r("\\d\\d\\d-(\\d\\d\\d)");
  49
  50     using namespace boost::program_options;
  51
  52     // Make sure no previous assignment to 'a' was made.
  53     validators::check_first_occurrence(v);
  54     // Extract the first string from 'values'. If there is more than
  55     // one string, it's an error, and exception will be thrown.
  56     const string& s = validators::get_single_string(values);
  57
  58     // Do regex match and convert the interesting part to
  59     // int.
  60     smatch match;
  61     if (regex_match(s, match, r)) {
  62         v = any(magic_number(lexical_cast<int>(match[1])));
  63     } else {
  64         throw validation_error(validation_error::invalid_option_value);
  65     }
  66 }
  67
  68
  69 int main(int ac, char* av[])
  70 {
  71     try {
  72         options_description desc("Allowed options");
  73         desc.add_options()
  74             ("help", "produce a help screen")
  75             ("version,v", "print the version number")
  76             ("magic,m", value<magic_number>(),
  77                  "magic value (in NNN-NNN format)")
  78             ;
  79
  80         variables_map vm;
  81         store(parse_command_line(ac, av, desc), vm);
  82
  83         if (vm.count("help")) {
  84             cout << "Usage: regex [options]\n";
  85             cout << desc;
  86             return 0;
  87         }
  88         if (vm.count("version")) {
  89             cout << "Version 1.\n";
  90             return 0;
  91         }
  92         if (vm.count("magic")) {
  93             cout << "The magic is \""
  94                  << vm["magic"].as<magic_number>().n << "\"\n";
  95         }
  96     }
  97     catch(std::exception& e)
  98     {
  99         cout << e.what() << "\n";
 100     }
 101 }