docopt2ragel makes command line interface parsing easy!

docopt2ragel parses docopt USAGE text and outputs a Ragel finite state machine for parsing the CLI.

You can then use Ragel to output the finite state machine into C source code.

Create a USAGE file using docopt's declarative format. See below for example contents:

dq - a command line tool for duraqueue the dead simple queue

Usage:
  dq info <queue_file>
  dq --help

Options:
  -h --help  Prints a short usage summary.

Convert the USAGE file into a Ragel file:

docopt2ragel.py USAGE > usage.rl 

Convert the Ragel file into a C file:

ragel usage.rl 

Import the generated file into your source:

#include "usage.c"

int main(int argc, char **argv)
{
    int e;
    options_t opts;

    e = parse_options(argc, argv, &opts);
    if (-1 == e)
    {
        exit(-1);
    }

    void *qu = NULL;

    if (opts.help)
    {
        show_usage();
        exit(0);
    }
    else if (opts.info)
    {
        qu = dqueuer_open(opts.queue_file);
    }

    if (qu)
        printf("Item count: %d\n", dqueue_count(qu));

    return 1;
}

For real life examples see:

• https://github.com/willemt/duraqueue
• https://github.com/willemt/peardb