Derive Macro InsertOnlySet

#[derive(InsertOnlySet)]

A procedural macro to generate an insert-only set for any enum.

This macro generates a struct with insert, contains, and iter methods for an enum. The struct uses OnceLock for thread-safe, one-time insertion of enum variants.

Examples

use insert_only_set::InsertOnlySet;

#[derive(InsertOnlySet, Debug, PartialEq)]
pub enum Type {
    Customer,
    Employee,
}

fn main() {
    let set = Type::InsertOnlySet();

    assert!(!set.contains(Type::Customer));
    assert!(!set.contains(Type::Employee));

    set.insert(Type::Customer);
    assert!(set.contains(Type::Customer));
    assert!(!set.contains(Type::Employee));

    set.insert(Type::Employee);
    assert!(set.contains(Type::Customer));
    assert!(set.contains(Type::Employee));

    for variant in set.iter() {
        println!("{:?}", variant);
    }
}