gethin

A small (400 sloc) cross-platform single-header c++11 CLI parser library

About

Ever being tired of not having a simple cross-platform getopts style CLI parser for your C++ projects? I have, so I wrote my own, gethin (and then I found out that other people also have ;-)). gethin supports shortopts, longopts and windows-style opts in a quite flexible way. Some examples:

app -o argument
app --option argument
app /o argument
app /option argument

app --option=argument
app --option="argument"
app --option:argument
app --option:"argument"

As this is a single-header library, you only need to include the the gethin.hpp header in the single_include folder. It is also available with the different classes in separate header files. The library in separated header files are available in the include folder. Using the library this way may decrease compilation times if some gethin classes are included in multiple source files.

Usage

There are three types of options you can parse: String, Flag and Set.

1. Create the options you need.
2. Create an OptionReader object. Supply the options to the constructor.
3. Call read() on the OptionReader object with argc and argv.
4. Call value() on the options to get the parsed arguments.

Example:

#include <iostream>
#include "gethin.hpp"

void drawRectangle(int width, int height);
void drawEllipse(int width, int height);

int main(int argc, char* argv[]) {
  gethin::String width = gethin::String()
                             .shortOpt('x')
                             .longOpt("width")
                             .mandatory()
                             .name("width")
                             .help("The width of the drawn shape.");

  gethin::String height = gethin::String()
                              .shortOpt('y')
                              .longOpt("height")
                              .mandatory()
                              .name("height")
                              .help("The height of the shape.");

  gethin::Flag color = gethin::Flag().shortOpt('c').longOpt("colors").help(
      "Draw the shape with colored output.");

  gethin::Set shape = gethin::Set()
                          .shortOpt('s')
                          .longOpt("shape")
                          .mandatory()
                          .alternatives({"rectangle", "ellipse"})
                          .help("Which shape to draw.");

  gethin::OptionReader optReader({&width, &height, &color, &shape});
  try {
    optReader.read(argc, argv);
  } catch (const std::invalid_argument& e) {
    std::cerr << e.what() << std::endl;
  } catch (...) {
    std::cerr << "Error during execution!" << std::endl;
  }

  if (shape.value() == "rectangle") {
    drawRectangle(std::stoi(width.value()), std::stoi(height.value()));
  } else if (shape.value() == "ellipse") {
    drawEllipse(std::stoi(width.value()), std::stoi(height.value()));
  }
}

Example

An example is included in the example folder. It is built with the make-target all. To build it, just run the command make. Execute the example by running ./drawshape.

Tests

The unit tests can be found in test/. The test framework Catch2 is used to write and execute the tests. Catch2 is included as a submodule in this repo. To be able to build the test, the Catch2 submodule must be present. Either clone the repo with the switch --recurse-submodules, or run the command git submodule init && git submodule update. The unit tests can be built and executed by running make test. They document the usage and the (few) caveats of this lib.

As we say in swedish, "Mycket nöje!"