miniarg

A minimal argument parser, with support for no-std and no-alloc

It mostly supports cmdlines in the form of program -foo value -bar value. That means:

• values are strings
• keys start with a single dash
• keys can occur multiple times

The last parameter can also be just a key without a value. (This can be useful for -help.)

Usage

Add this to your Cargo.toml:

[dependencies]
miniarg = "0.5"

The feature std is enabled by default and alloc and derive are optional.

Examples

A minimal example looks like this:

let cmdline = "executable -key value";
let mut args = miniarg::parse(&cmdline, &["key"]);
assert_eq!(args.next(), Some(Ok((&"key", "value"))));
assert_eq!(args.next(), None);

If you don't want to pass a cmdline, you can use an iterator instead:

let iter = vec!["executable", "-key", "value"].into_iter();
let mut args = miniarg::parse_from_iter(iter, &["key"]);
assert_eq!(args.next(), Some(Ok((&"key", "value"))));
assert_eq!(args.next(), None);

You can use collect::<Result<Vec<_>, _>>() to get a Vec:

let cmdline = "executable -key value";
let args = miniarg::parse(&cmdline, &["key"]).collect::<Result<Vec<_>, _>>()?;
assert_eq!(args, vec![(&"key", "value")]);

If you compile with std or alloc, it also supports passing ToString instead of strings, for example your own enum:

#[derive(Debug, PartialEq)]
enum MyKeys {
    Foo,
    Bar,
}
impl std::fmt::Display for MyKeys {
    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
        std::fmt::Debug::fmt(self, f)
    }
}
let cmdline = "executable -foo value -bar value";
let args = miniarg::parse(&cmdline, &[MyKeys::Foo, MyKeys::Bar])
.collect::<Result<Vec<_>, _>>()?;
assert_eq!(args, vec![(&MyKeys::Foo, "value"), (&MyKeys::Bar, "value")]);

As you can see, the first character of the enum kinds is converted to lowercase.

If you compile with derive, you can use a custom derive instead:

#[derive(Debug, Key, PartialEq)]
enum MyKeys {
    Foo,
    Bar,
}
let cmdline = "executable -foo value -bar value";
let args = MyKeys::parse(&cmdline).collect::<Result<Vec<_>, _>>()?;
assert_eq!(args, vec![(&MyKeys::Foo, "value"), (&MyKeys::Bar, "value")]);

In this case a help text is generated from the documentation comments on your enum kinds, help_text() retrieves it.

The code never panics, but the returned iterator will contain ParseErrors if anything goes wrong.

You might also want to take a look at the split_args module for lower level access.

License: MPL-2.0