enum_ordinalize/
traits.rs

1/// This trait provides an enum with the ability to not only obtain the ordinal values of its variants but also allows for the construction of enums from an ordinal value.
2///
3/// ```rust
4/// use enum_ordinalize::Ordinalize;
5///
6/// #[repr(u8)]
7/// enum E {
8///     A,
9///     B,
10/// }
11///
12/// impl Ordinalize for E {
13///     type VariantType = u8;
14///
15///     const VALUES: &'static [Self::VariantType] = &[0, 1];
16///     const VARIANTS: &'static [Self] = &[E::A, E::B];
17///     const VARIANT_COUNT: usize = 2;
18///
19///     #[inline]
20///     unsafe fn from_ordinal_unsafe(number: Self::VariantType) -> Self {
21///         ::core::mem::transmute(number)
22///     }
23///
24///     #[inline]
25///     fn from_ordinal(number: Self::VariantType) -> Option<Self> {
26///         match number {
27///             0 => Some(Self::A),
28///             1 => Some(Self::B),
29///             _ => None,
30///         }
31///     }
32///
33///     #[inline]
34///     fn ordinal(&self) -> Self::VariantType {
35///         match self {
36///             Self::A => 0,
37///             Self::B => 1,
38///         }
39///     }
40/// }
41/// ```
42pub trait Ordinalize: Sized + 'static {
43    /// The type of the values of the variants.
44    type VariantType;
45
46    /// The count of variants.
47    const VARIANT_COUNT: usize;
48
49    /// List of this enum's variants.
50    const VARIANTS: &'static [Self];
51
52    /// List of values for all variants of this enum.
53    const VALUES: &'static [Self::VariantType];
54
55    /// Obtain a variant based on an integer number.
56    ///
57    /// # Safety
58    /// You have to ensure that the input integer number can correspond to a variant on your own.
59    unsafe fn from_ordinal_unsafe(number: Self::VariantType) -> Self;
60
61    /// Obtain a variant based on an integer number.
62    fn from_ordinal(number: Self::VariantType) -> Option<Self>
63    where
64        Self: Sized;
65
66    /// Retrieve the integer number of this variant.
67    fn ordinal(&self) -> Self::VariantType;
68}
enum_ordinalize/traits.rs

enum_ordinalize/
traits.rs
