recap

C++ library for command line argument parsing.

How to build

Prerequisites

1. Project written in c++20, therefore GCC 10.2 or Clang 12.0.0 and libstdc++10 or libc++7 recommended.

Building project

1. Run makefile

   make

Installing

1. Install library

   make install

Running tests

1. Clone googletest into project root directory.

   git clone https://github.com/google/googletest.git

2. Run tests

   make test

Usage

Args

To use create an instance of Parser and add arg your app requires.

Parser parser = ParserBuilder("app_name").get();
parser.add_argument(ArgBuilder("cl_arg").get());

Parse command line arguments.

// ./app --cl_arg value
parser.parse(argc, argv);

Then you can access args value by its name.

auto res = parser.get("cl_arg");

Result is std::optional. Contains value only if supplied or default value was given at the creation.

std::cout << res.value_or("was not given any value");

Flags and positional args

Besides named args (i.e. options), flags and positional args are available.

parser.add_flag(FlagBuilder("flag").get());
parser.add_positional_argument(PositionalArgBuilder("pos_arg").get());

// ./app pos_value -f
parser.parse(argc, argv);
assert(true == parser.was_toggled("flag"));
assert(std::string{"pos_value"} == parser.get("pos_arg").value());

NOTE: While creating positional argument it can be assigned default (current highest + 1 starting at 0) or user defined order number using order() method. Order only refers to position according to other positional arguments.

NOTE: Additionally positional args may be marked as required with required() function. While it makes no sense for required args to follow not required (unless implicitly forcing them to be required as well) it is not validated in any way.

Conditions

Args can be supplied with conditions. Value will only be set if it meets all conditions.

auto is_whole_upper = [](const std::string& s) {
    return std::all_of(s.begin(), s.end(), [](unsigned char c){ 
        return !std::islower(c); 
    });
};
parser.add_argument(
    ArgBuilder("upper")
        .with_condition(Condition("IsWholeUpper", is_whole_upper))
        .get()
);
try {
    // ./app -u not_upper
    parser.parse(argc, argv);
    assert(false);
} catch(...) {}

More complex examples can be found in examples directory.