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/// 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.
///
/// ```rust
/// use enum_ordinalize::Ordinalize;
///
/// #[repr(u8)]
/// enum E {
/// A,
/// B,
/// }
///
/// impl Ordinalize for E {
/// type VariantType = u8;
///
/// const VALUES: &'static [Self::VariantType] = &[0, 1];
/// const VARIANTS: &'static [Self] = &[E::A, E::B];
/// const VARIANT_COUNT: usize = 2;
///
/// #[inline]
/// unsafe fn from_ordinal_unsafe(number: Self::VariantType) -> Self {
/// ::core::mem::transmute(number)
/// }
///
/// #[inline]
/// fn from_ordinal(number: Self::VariantType) -> Option<Self> {
/// match number {
/// 0 => Some(Self::A),
/// 1 => Some(Self::B),
/// _ => None,
/// }
/// }
///
/// #[inline]
/// fn ordinal(&self) -> Self::VariantType {
/// match self {
/// Self::A => 0,
/// Self::B => 1,
/// }
/// }
/// }
/// ```
pub trait Ordinalize: Sized + 'static {
/// The type of the values of the variants.
type VariantType;
/// The count of variants.
const VARIANT_COUNT: usize;
/// List of this enum's variants.
const VARIANTS: &'static [Self];
/// List of values for all variants of this enum.
const VALUES: &'static [Self::VariantType];
/// Obtain a variant based on an integer number.
///
/// # Safety
/// You have to ensure that the input integer number can correspond to a variant on your own.
unsafe fn from_ordinal_unsafe(number: Self::VariantType) -> Self;
/// Obtain a variant based on an integer number.
fn from_ordinal(number: Self::VariantType) -> Option<Self>
where
Self: Sized;
/// Retrieve the integer number of this variant.
fn ordinal(&self) -> Self::VariantType;
}
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