num_enum 0.7.6

Procedural macros to make inter-operation between primitives and enums easier.
Documentation 
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use ::num_enum::FromPrimitive;

// Guard against https://github.com/illicitonion/num_enum/issues/27
mod alloc {}
mod core {}
mod num_enum {}
mod std {}

macro_rules! has_from_primitive_number {
    ( $type:ty ) => {
        paste::paste! {
            #[test]
            fn [<has_from_primitive_number_ $type>]() {
                #[derive(Debug, Eq, PartialEq, FromPrimitive)]
                #[repr($type)]
                enum Enum {
                    Zero = 0,
                    #[num_enum(default)]
                    NonZero = 1,
                }

                let zero = Enum::from_primitive(0 as $type);
                assert_eq!(zero, Enum::Zero);

                let one = Enum::from_primitive(1 as $type);
                assert_eq!(one, Enum::NonZero);

                let two = Enum::from_primitive(2 as $type);
                assert_eq!(two, Enum::NonZero);
            }
        }
    };
}

has_from_primitive_number!(u8);
has_from_primitive_number!(u16);
has_from_primitive_number!(u32);
has_from_primitive_number!(u64);
has_from_primitive_number!(usize);
has_from_primitive_number!(i8);
has_from_primitive_number!(i16);
has_from_primitive_number!(i32);
has_from_primitive_number!(i64);
has_from_primitive_number!(isize);
// repr with 128-bit type is unstable
// has_from_primitive_number!(u128);
// has_from_primitive_number!(i128);

#[test]
fn has_from_primitive_number_standard_default_attribute() {
    #[derive(Debug, Eq, PartialEq, FromPrimitive)]
    #[repr(u8)]
    enum Enum {
        Zero = 0,
        #[default]
        NonZero = 1,
    }

    let zero = Enum::from_primitive(0_u8);
    assert_eq!(zero, Enum::Zero);

    let one = Enum::from_primitive(1_u8);
    assert_eq!(one, Enum::NonZero);

    let two = Enum::from_primitive(2_u8);
    assert_eq!(two, Enum::NonZero);
}

#[test]
fn from_primitive_number() {
    #[derive(Debug, Eq, PartialEq, FromPrimitive)]
    #[repr(u8)]
    enum Enum {
        #[num_enum(default)]
        Whatever = 0,
    }

    // #[derive(FromPrimitive)] generates implementations for the following traits:
    //
    // - `FromPrimitive<T>`
    // - `From<T>`
    // - `TryFromPrimitive<T>`
    // - `TryFrom<T>`
    let from_primitive = Enum::from_primitive(0_u8);
    assert_eq!(from_primitive, Enum::Whatever);

    let from = Enum::from(0_u8);
    assert_eq!(from, Enum::Whatever);

    let from_primitive = Enum::from_primitive(1_u8);
    assert_eq!(from_primitive, Enum::Whatever);

    let from = Enum::from(1_u8);
    assert_eq!(from, Enum::Whatever);
}

#[test]
fn from_primitive_number_catch_all() {
    #[derive(Debug, Eq, PartialEq, FromPrimitive)]
    #[repr(u8)]
    enum Enum {
        Zero = 0,
        #[num_enum(catch_all)]
        NonZero(u8),
    }

    let zero = Enum::from_primitive(0_u8);
    assert_eq!(zero, Enum::Zero);

    let one = Enum::from_primitive(1_u8);
    assert_eq!(one, Enum::NonZero(1_u8));

    let two = Enum::from_primitive(2_u8);
    assert_eq!(two, Enum::NonZero(2_u8));
}

#[test]
fn from_primitive_number_catch_all_in_middle() {
    #[derive(Debug, PartialEq, Eq, FromPrimitive)]
    #[repr(u8)]
    enum Enum {
        Zero = 0,
        #[num_enum(catch_all)]
        Else(u8) = 2,
        One = 1,
    }

    let zero = Enum::from_primitive(0_u8);
    assert_eq!(zero, Enum::Zero);

    let one = Enum::from_primitive(1_u8);
    assert_eq!(one, Enum::One);

    let two = Enum::from_primitive(2_u8);
    assert_eq!(two, Enum::Else(2_u8));

    let three = Enum::from_primitive(3_u8);
    assert_eq!(three, Enum::Else(3_u8));
}

#[cfg(feature = "complex-expressions")]
#[test]
fn from_primitive_number_with_inclusive_range() {
    #[derive(Debug, Eq, PartialEq, FromPrimitive)]
    #[repr(u8)]
    enum Enum {
        Zero = 0,
        #[num_enum(alternatives = [2..=255])]
        NonZero,
    }

    let zero = Enum::from_primitive(0_u8);
    assert_eq!(zero, Enum::Zero);

    let one = Enum::from_primitive(1_u8);
    assert_eq!(one, Enum::NonZero);

    let two = Enum::from_primitive(2_u8);
    assert_eq!(two, Enum::NonZero);

    let three = Enum::from_primitive(3_u8);
    assert_eq!(three, Enum::NonZero);

    let twofivefive = Enum::from_primitive(255_u8);
    assert_eq!(twofivefive, Enum::NonZero);
}