102 lines
2.9 KiB
C++
102 lines
2.9 KiB
C++
// Copyright Vladimir Prus 2002-2004.
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// Distributed under the Boost Software License, Version 1.0.
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// (See accompanying file LICENSE_1_0.txt
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// or copy at http://www.boost.org/LICENSE_1_0.txt)
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// This example shows how a user-defined class can be parsed using
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// specific mechanism -- not the iostream operations used by default.
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//
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// A new class 'magic_number' is defined and the 'validate' method is overloaded
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// to validate the values of that class using Boost.Regex.
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// To test, run
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//
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// regex -m 123-456
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// regex -m 123-4567
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//
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// The first invocation should output:
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//
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// The magic is "456"
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//
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// and the second invocation should issue an error message.
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#include <boost/program_options.hpp>
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#include <boost/regex.hpp>
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using namespace boost;
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using namespace boost::program_options;
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#include <iostream>
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using namespace std;
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/* Define a completely non-sensical class. */
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struct magic_number {
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public:
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magic_number(int n) : n(n) {}
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int n;
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};
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/* Overload the 'validate' function for the user-defined class.
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It makes sure that value is of form XXX-XXX
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where X are digits and converts the second group to an integer.
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This has no practical meaning, meant only to show how
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regex can be used to validate values.
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*/
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void validate(boost::any& v,
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const std::vector<std::string>& values,
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magic_number*, int)
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{
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static regex r("\\d\\d\\d-(\\d\\d\\d)");
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using namespace boost::program_options;
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// Make sure no previous assignment to 'a' was made.
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validators::check_first_occurrence(v);
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// Extract the first string from 'values'. If there is more than
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// one string, it's an error, and exception will be thrown.
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const string& s = validators::get_single_string(values);
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// Do regex match and convert the interesting part to
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// int.
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smatch match;
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if (regex_match(s, match, r)) {
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v = any(magic_number(lexical_cast<int>(match[1])));
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} else {
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throw validation_error(validation_error::invalid_option_value);
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}
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}
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int main(int ac, char* av[])
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{
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try {
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options_description desc("Allowed options");
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desc.add_options()
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("help", "produce a help screen")
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("version,v", "print the version number")
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("magic,m", value<magic_number>(),
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"magic value (in NNN-NNN format)")
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;
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variables_map vm;
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store(parse_command_line(ac, av, desc), vm);
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if (vm.count("help")) {
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cout << "Usage: regex [options]\n";
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cout << desc;
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return 0;
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}
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if (vm.count("version")) {
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cout << "Version 1.\n";
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return 0;
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}
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if (vm.count("magic")) {
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cout << "The magic is \""
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<< vm["magic"].as<magic_number>().n << "\"\n";
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}
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}
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catch(std::exception& e)
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{
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cout << e.what() << "\n";
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}
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}
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