Struct forma::buffer::layout::SliceCache

pub struct SliceCache { /* private fields */ }

A cache of non-overlapping mutable sub-slices of that enforces lifetimes dynamically.

This type is useful when you have to give up on the mutable reference to a slice but need a way to cache mutable sub-slices deriving from it.

Examples

let mut array = [1, 2, 3];

let mut cache = SliceCache::new(3, |span| {
    let (left, right) = span.split_at(1);
    Box::new([left, right])
});

for slice in cache.access(&mut array).unwrap().iter_mut() {
    for val in slice.iter_mut() {
        *val += 1;
    }
}

assert_eq!(array, [2, 3, 4]);

Implementations

impl SliceCache

pub fn new<F>(len: usize, f: F) -> SliceCache

where F: Fn(Span<'_>) -> Box<[Span<'_>]> + 'static,

Creates a new slice cache by storing sub-spans created from a root passed to the closure f. len is the minimum slice length that can then be passed to access.

Examples

let mut cache = SliceCache::new(3, |span| {
    let (left, right) = span.split_at(1);
    // All returned sub-spans stem from the span passed above.
    Box::new([left, right])
});

pub fn access<'c, 's, T>( &'c mut self, slice: &'s mut [T] ) -> Option<Ref<'c, [Slice<'s, T>]>>

Accesses the slice by returning all the sub-slices equivalent to the previously created spans in the closure passed to new.

If the slice does not have a length at least as large as the one passed to new, this function returns None.

Note: this method should not be called concurrently with any other access calls since it will wait for the previously returned Ref to be dropped.

Examples

let mut array = [1, 2, 3];

let mut cache = SliceCache::new(3, |span| {
    let (left, right) = span.split_at(1);
    Box::new([left, right])
});

let mut copy = array;
let skipped_one = cache.access(&mut array).unwrap();

assert_eq!(&*skipped_one[1], &copy[1..]);

Trait Implementations

impl Debug for SliceCache

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.