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:
magic_numbermagic_number34 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 */
validate(boost::any & v,const std::vector<std::string> & values,magic_number *,int)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
main(int ac,char * av[])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 }
102