kuri::option -- argument parsing

A simple library handling command line options. The purpose of this header only library is to handle the easiest and most common cases of command line arguments.

• Boolean and options with a string value
• Options taking values accepts --option value or --option=value
• Only one string per option
• Processing of options through callbacks
• Grouping of options
• Sub commands
• Helper function to parse number ranges (e.g. 1-3,5,7-)
• Min and max number of arguments after the options
• Conventional use of double hyphen (--) to signal end of options
• Builds the help and usage string automatically

Let's start with a basic example to illustrate some of the features: A program which takes two options, one boolean and one with a string value, followed by an arbitrary number of arguments.

The example is also available examples/basic.cc.

#include <string>
#include <iostream>
#include <iomanip>
#include <optional>
#include <option/Program.hh>

using namespace kuri;

int main(int argc, char** argv)
{
  try
  {
    // Collect the arguments from `argv` into a vector<string>.
    //
    option::args_t args{argv + 1, argv + argc};
    //
    // Define the variables which we will set when the options are processed.
    //
    auto verbose = false;
    std::optional<std::string> print;
    //
    // Create the `Program` object and add the options.  Finally we call the
    // `parse` member function to do the parsing.  The return value is a pair
    // of iterators in the original vector of arguments.
    //
    auto result = option::Program(option::basename(argv[0]))
      .optional("--verbose", [&]() { verbose = true; })
      .optional("--print", [&](const option::Option& o) {
        print = o.value;
      })
      .args()
      .parse(args.begin(), args.end());
    //
    // Now print the result of
    //
    std::cout << "verbose = " << std::boolalpha << verbose << '\n';
    if (print)
      std::cout << "print = " << *print << '\n';
    for(auto i = result; i != args.end(); ++i)
      std::cout << "arg = " << *i << '\n';
  }
  catch(const option::usage_error& e)
  {
    // In case of errors `Program` throws the exception `usage_error`.
    //
    std::cerr << e.what() << '\n';
  }
}

License

Copyright 2021 Krister Joas

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.