slic

Simple C++20 command line argument parser.

Features

• Single header file
• Zero allocations
• No dependencies
• Compile-time configuration and validation
• Supports positional and named arguments
• Variadic arguments support
• Type-safe parsing of arguments
• Help message generation
• Error handling

Usage

Here's a simple example of how to use slic to parse command line arguments:

#include <slic.hpp>

// Define your argument struct
struct MyArgs {
    std::string_view input;
    std::string_view output;
    std::string_view test;
    int number = 0;
    bool version = false;
    slic::ArgSpan args;

    static constexpr std::string_view Description = "My awesome CLI tool";
    static constexpr std::tuple Options = {
        slic::Option{"--number", "-n", &MyArgs::number, "Some number"},
        slic::Option{"--version", "-v", &MyArgs::version, "Show version"},
        slic::Option{"--test", "-t", &MyArgs::test, "Test argument"},
        slic::Arg{"INPUT", &MyArgs::input, "Input file"},
        slic::Arg{"OUTPUT", &MyArgs::output, "Output file"},
        slic::VarArgs{"Extra files", &MyArgs::args}
    };
};

int main(int argc, char** argv) {
    // Create the parser
    slic::ArgParser<MyArgs> parser(argc, argv);
    
    // Parse the arguments and handle errors
    auto result = parser.parse();
    if (!result) {
        result.print();
        // you can also print help message if needed
        parser.printHelp();
        return 1;
    }
    
    MyArgs const& args = parser.result(); // parser holds your struct
    
    // access members directly
    if (args.version) {
        std::cout << "My CLI Tool version 1.0.0\n";
        return 0;
    }
    
    // access variadic arguments
    for (std::string_view arg : args.args) {
        std::cout << "Extra arg: " << arg << "\n";
    }
    
    return 0;
}

Help message output for the above example:

My awesome CLI tool

Usage: my_program [OPTIONS] <INPUT> <OUTPUT> [...]

Arguments:
  INPUT: Input file
  OUTPUT: Output file
  [...]: Extra files

Options:
  -n, --number <value>: Some number
  -v, --version: Show version
  -t, --test <value>: Test argument

Benchmarks

Some benchmarks comparing slic with other popular C++ command line parsers:

• CLI11 (v2.6.1)
• cxxopts (v3.3.1)
• argparse (v3.2)

Benchmarks were run on an AMD Ryzen 7 7730U using Google Benchmark library in Release mode with -O3 optimizations.

1. Simple case

program -v --count 42 myfile.txt

Library	Time (ns)	CPU (ns)	Iterations
slic	51.8	51.6	13126669
CLI11	5752	5749	117156
cxxopts	7951	7951	71121
argparse	3531	3531	200750

2. Medium case

program -v --count 42 --name test --level 3 --output out.txt input.txt

Library	Time (ns)	CPU (ns)	Iterations
slic	135	135	5237956
CLI11	12998	12995	54427
cxxopts	15516	15510	43210
argparse	6582	6577	114666

3. Complex case

program -v --count 42 --name test --level 3 --output out.txt --debug --threads 8 --timeout 1000 --retry 3 input1.txt input2.txt

Library	Time (ns)	CPU (ns)	Iterations
slic	412	412	2178409
CLI11	28640	28623	25571
cxxopts	36981	36940	22162
argparse	11283	11278	59623

4. Flags only

program -a -b -c -d -e -f -g -h

Library	Time (ns)	CPU (ns)	Iterations
slic	358	358	2089557
CLI11	12266	12259	57548
cxxopts	17721	17711	55006
argparse	5063	5061	135891

License

This project is licensed under the MIT License. See the LICENSE file for details.