Struct IdxBox 

pub struct IdxBox<Idx> { /* private fields */ }

An allocation of bounded indices that can be retrieved with a bound.

The usefulness comes from the fact that there is not tag on the type but instead one is assigned when retrieving the contents. In particular you don’t need a unique type to construct this container.

Implementations

impl<I: HiddenMaxIndex> IdxBox<I>

pub fn new(indices: Box<[I]>) -> Result<Self, Box<[I]>>

Wrap an allocation of indices. This will fail if it not possible to express the lower bound of slices for which all indices are valid, as a usize. That is, if any of the indices references the element with index usize::MAX itself.

pub fn bound(&self) -> usize

Return the upper bound over all indices. This is not guaranteed to be the least upper bound.

pub fn ensure(&mut self, min: usize)

Ensure that the stored bound is at least min.

pub fn truncate(&mut self)

Set the bound to the least upper bound of all indices.

This always reduces the bound and there can not be any lower bound that is consistent with all indices stored in this IdxBox.

pub fn as_ref<T: Tag>(&self, size: Prefix<T>) -> Option<&[Idx<I, T>]>

Reinterpret the contents as indices of a given tag.

The given size must not be smaller than the bound of this allocated. This guarantees that all indices within the box are valid for the Tag. Since you can only view the indices, they will remain valid.

pub fn as_mut<T: Tag>(&mut self, size: ExactSize<T>) -> Option<&mut [Idx<I, T>]>

Reinterpret the contents as mutable indices of a given tag.

The given exact size must not be exactly the same as the bound of this allocated slice. This guarantees that all indices within the box are valid for the Tag, and that all stored indices will be valid for all future tags.