feat: add conversion methods

This commit is contained in:
Leonora Tindall 2021-11-07 12:53:43 -06:00
parent 50bca2ae86
commit f6d43cd200
Signed by: nora
GPG Key ID: 7A8B52EC67E09AAF
1 changed files with 77 additions and 5 deletions

View File

@ -19,6 +19,16 @@ use std::slice;
/// `MinSlice` is merely a way of reinterpreting an existing slice
/// (`&[T]` or `&mut [T]`), and it is exactly the same size as a slice:
/// one pointer and one `usize`.
///
/// # Example
///
/// ```
/// # use nslice::MinSlice;
/// let slice: &[u8] = b"Hello, world";
/// let minslice = MinSlice::<u8, 12>::from_slice(slice).unwrap();
/// let value: u8 = minslice.head[6];
/// assert_eq!(value, b' ')
/// ```
pub struct MinSlice<T, const N: usize> {
/// The bounded region of memory. Exactly `N` `T`s.
pub head: [T; N],
@ -47,7 +57,7 @@ impl<T, const N: usize> MinSlice<T, N> {
None
}
}
/// Produce a `&mut MinSlice` from a mutable slice of `T`s.
/// Returns `None` if there are not enough elements in `slice`.
pub fn from_mut(slice: &mut [T]) -> Option<&mut MinSlice<T, N>> {
@ -57,6 +67,56 @@ impl<T, const N: usize> MinSlice<T, N> {
None
}
}
}
impl<T, const N: usize> MinSlice<T, N> {
/// Returns a slice over the memory referred to by the `MinSlice`.
/// Its length is guaranteed to be no less than `N`.
pub fn as_slice(&self) -> &[T] {
unsafe { slice::from_raw_parts(self.head.as_ptr(), N + self.tail.len()) }
}
/// Returns a mutable slice over the memory referred to by the `MinSlice`.
/// Its length is guaranteed to be no less than `N`.
pub fn as_mut_slice(&mut self) -> &mut [T] {
unsafe { slice::from_raw_parts_mut(self.head.as_mut_ptr(), N + self.tail.len()) }
}
/// Resize the `MinSlice`, returning a new `Some(&MinSlice<T, M>)`
/// if there are at least `M` `T`s in `self`.
pub fn resize<const M: usize>(&self) -> Option<&MinSlice<T, M>> {
MinSlice::<T, M>::from_slice(self.as_slice())
}
/// Resize the `MinSlice`, returning a new `Some(&mut MinSlice<T, M>)`
/// if there are at least `M` `T`s in `self`.
pub fn resize_mut<const M: usize>(&mut self) -> Option<&mut MinSlice<T, M>> {
MinSlice::<T, M>::from_mut(self.as_mut_slice())
}
/// Get a reference to a value from the `MinSlice` by index.
///
/// Return `Some(&T)` for the `T` at index `i` if `i < (N + self.tail.len)`,
/// or `None` otherwise.
pub fn get(&self, i: usize) -> Option<&T> {
if i < N {
Some(&self.head[i])
} else {
self.tail.get(i)
}
}
/// Get a mutable reference to a value from the `MinSlice` by index.
///
/// Return `Some(&mut T)` for the `T` at index `i` if `i < (N + self.tail.len)`,
/// or `None` otherwise.
pub fn get_mut(&mut self, i: usize) -> Option<&mut T> {
if i < N {
Some(&mut self.head[i])
} else {
self.tail.get_mut(i)
}
}
/// Produce a `&MinSlice` from a slice of `T`s without checking its length.
///
@ -112,14 +172,26 @@ impl<T, const N: usize> ExactSlice<T, N> {
}
}
/// Returns a slice over the memory referred to by the `ExactSlice`.
/// Its length is guaranteed to be exactly `N`.
pub fn as_slice(&self) -> &[T] {
unsafe { slice::from_raw_parts(self.head.as_ptr(), N) }
}
/// Returns a mutable slice over the memory referred to by the `ExactSlice`.
/// Its length is guaranteed to be exactly `N`.
pub fn as_mut_slice(&mut self) -> &mut [T] {
unsafe { slice::from_raw_parts_mut(self.head.as_mut_ptr(), N) }
}
/// Produce a `&MinSlice` from this `&ExactSlice`. Its `tail` will be empty.
pub fn as_min_slice(&self) -> Option<&MinSlice<T, N>> {
MinSlice::from_slice(&self.head[..])
pub fn as_min_slice(&self) -> &MinSlice<T, N> {
unsafe { MinSlice::from_slice_unchecked(&self.head[..]) }
}
/// Produce a `&mut MinSlice` from this `&min ExactSlice`. Its `tail` will be empty.
pub fn as_mut_min_slice(&mut self) -> Option<&mut MinSlice<T, N>> {
MinSlice::from_mut(&mut self.head[..])
pub fn as_mut_min_slice(&mut self) -> &mut MinSlice<T, N> {
unsafe { MinSlice::from_mut_unchecked(&mut self.head[..]) }
}
/// Produce an `&ExactSlice` from a slice of `T`s without checking its length.