Trait beef::Beef

pub unsafe trait Beef: ToOwned {
    fn capacity(owned: &Self::Owned) -> Option<NonZeroUsize>;
    unsafe fn owned_ptr(owned: &mut Self::Owned) -> NonNull<Self>;
    unsafe fn rebuild(ptr: NonNull<Self>, capacity: usize) -> Self::Owned;
}

Helper trait required by Cow<T> to extract capacity of owned variant of T, and manage conversions.

This can be only implemented on types that match requirements:

• T::Owned has a capacity, which is an extra word that is absent in T.
• T::Owned with capacity of 0 does not allocate memory.
• T::Owned can be reconstructed from *mut T borrowed out of it, plus capacity.

Required methods

fn capacity(owned: &Self::Owned) -> Option<NonZeroUsize>

Get capacity of owned variant of T. Return None for 0. Returning invalid capacity will lead to undefined behavior.

unsafe fn owned_ptr(owned: &mut Self::Owned) -> NonNull<Self>

Convert &mut T::Owned to *mut T, stripping capacity.

unsafe fn rebuild(ptr: NonNull<Self>, capacity: usize) -> Self::Owned

Rebuild T::Owned from NonNull<T> and capacity. This can be done by the likes of Vec::from_raw_parts.

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Implementors

impl Beef for str

fn capacity(owned: &String) -> Option<NonZeroUsize>

unsafe fn owned_ptr(owned: &mut String) -> NonNull<str>

unsafe fn rebuild(ptr: NonNull<Self>, capacity: usize) -> String

impl<T: Clone> Beef for [T]

fn capacity(owned: &Vec<T>) -> Option<NonZeroUsize>

unsafe fn owned_ptr(owned: &mut Vec<T>) -> NonNull<[T]>

unsafe fn rebuild(ptr: NonNull<Self>, capacity: usize) -> Vec<T>

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