cliargs-rust

A library to parse command line arguments and print the help for Rust application.

This library provides the following functionalities:

• Supports POSIX & GNU like short and long options.
  • This library supports -- option.
  • This library doesn't support numeric short option.
  • This library supports not -ofoo but -o=foo as an alternative to -o foo for short option.
• Supports parsing with option configurations.
• Supports parsing with an object which stores option values and has annotations of fields. (To be added)
• Is able to parse command line arguments including sub commands. (To be added)
• Generates help text from option configurations. (To be added)

Install

In Cargo.toml, write this crate as a dependency.

[dependencies]
cliargs = "0.2.0"

Usage

This crate provides the Cmd struct to parse command line arguments. The usage of this Cmd struct is as follows:

Creates a Cmd instance

The Cmd::new function creates a Cmd instance with original command line arguments. This function uses std::env::args_os and OsString#into_string to read command line arguments in order to avoid panic! call that the user cannot control.

use cliargs::Cmd;
use cliargs::errors::InvalidOsArg;

let cmd = match Cmd::new() {
    Ok(cmd) => cmd,
    Err(InvalidOsArg::OsArgsContainInvalidUnicode { index, os_arg }) => {
        panic!("Invalid Unicode data: {:?} (index: {})", os_arg, index);
    }
};

Creates a Cmd instance with the specified String array

The Cmd::with_strings function creates a Cmd instance with the specified String array.

use cliargs::Cmd;
use std::env;

let cmd = Cmd::with_strings(env::args());

Creates a Cmd instance with the specified OsString array

The Cmd::with_os_strings function creates a Cmd instance with the specified OsString array.

use cliargs::Cmd;
use cliargs::errors::InvalidOsArg;
use std::env;

let cmd = match Cmd::with_os_strings(env::args_os()) {
    Ok(cmd) => cmd,
    Err(InvalidOsArg::OsArgsContainInvalidUnicode { index, os_arg }) => {
        panic!("Invalid Unicode data: {:?} (index: {})", os_arg, index);
    }
};

Parses without configurations

The Cmd struct has the method which parses command line arguments without configurations. This method automatically divides command line arguments to command arguments, options, and option arguments.

Command line arguments starts with - or -- are options, and others are command arguments. If you want to specify a value to an option, follows "=" and the value after the option, like foo=123.

All command line arguments after -- are command arguments, even they starts with - or --.

use cliargs::Cmd;
use cliargs::errors::InvalidOption;

let mut cmd = Cmd::with_strings(vec![ /* ... */ ]);
match cmd.parse() {
    Ok(_) => { /* ... */ },
    Err(InvalidOption::OptionContainsInvalidChar { option }) => {
        panic!("Option contains invalid character: {option}");
    },
    Err(err) => panic!("Invalid option: {}", err.option()),
}

Parses with configurations

The Cmd struct has the method parse_with which parses command line arguments with configurations. This method takes an array of option configurations: OptCfg, and divides command line arguments to options and command arguments according to this configurations..

An option configuration has fields: store_key, names, has_arg, is_array, defaults, desc, arg_in_help, and validator.

store_key field is specified the key name to store the option value to the option map in the Cmd instance. If this field is not specified, the first element of names field is used instead.

names field is a string array and specified the option names, that are both long options and short options. The order of elements in this field is used in a help text. If you want to prioritize the output of short option name first in the help text, like -f, --foo-bar, but use the long option name as the key in the option map, write store_key and names fields as follows: OptCfg::with(&[store_key("foo-bar"), names(&["f", "foo-bar"])]).

has_arg field indicates the option requires one or more values. is_array field indicates the option can have multiple values. defaults field is an array of string which is used as default one or more option arguments if the option is not specified. desc is a description of the option for help text. arg_n_help field is a text which is output after option name and aliases as an option value in help text.

validator field is to set a function pointer which validates an option argument. This crate provides the validator cliargs::validators::validate_number<T> which validates whether an option argument is valid format as a number.

use cliargs::{Cmd, OptCfg};
use cliargs::OptCfgParam::{names, has_arg, defaults, validator, desc, arg_in_help};
use cliargs::validators::validate_number;
use cliargs::errors::InvalidOption;

let mut cmd = Cmd::with_strings(vec![ /* ... */ ]);
let opt_cfgs = vec![
    OptCfg::with(&[
        names(&["foo-bar"]),
        desc("This is description of foo-bar."),
    ]),
    OptCfg::with(&[
        names(&["baz", "z"]),
        has_arg(true),
        defaults(&["1"]),
        desc("This is description of baz."),
        arg_in_help("<num>"),
        validator(validate_number::<u32>),
    ]),
];

match cmd.parse_with(&opt_cfgs) {
    Ok(_) => { /* ... */ },
    Err(InvalidOption::OptionContainsInvalidChar { option }) => { /* ... */ },
    Err(InvalidOption::UnconfiguredOption { option }) => { /* ... */ },
    Err(InvalidOption::OptionNeedsArg { option, .. }) => { /* ... */ },
    Err(InvalidOption::OptionTakesNoArg { option, .. }) => { /* ... */ },
    Err(InvalidOption::OptionIsNotArray { option, .. }) => { /* ... */ },
    Err(InvalidOption::OptionArgIsInvalid { option, opt_arg, details, .. }) => { /* ... */ },
    Err(err) => panic!("Invalid option: {}", err.option()),
}

Supporting Rust versions

This crate supports Rust 1.74.1 or later.

% cargo msrv --no-check-feedback
Fetching index
Determining the Minimum Supported Rust Version (MSRV) for toolchain x86_64-apple-darwin
Using check command cargo check
   Finished The MSRV is: 1.74.1   █████████████████████████████████████ 00:00:02

License

Copyright (C) 2024 Takayuki Sato

This program is free software under MIT License.
See the file LICENSE in this distribution for more details.