Type Alias gear_lazy_pages::PageSizes

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pub type PageSizes = [NonZeroU32; 2];

Implementations§

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impl<T, const N: usize> [T; N]

1.55.0 · source

pub fn map<F, U>(self, f: F) -> [U; N]where F: FnMut(T) -> U,

Returns an array of the same size as self, with function f applied to each element in order.

If you don’t necessarily need a new fixed-size array, consider using Iterator::map instead.

Note on performance and stack usage

Unfortunately, usages of this method are currently not always optimized as well as they could be. This mainly concerns large arrays, as mapping over small arrays seem to be optimized just fine. Also note that in debug mode (i.e. without any optimizations), this method can use a lot of stack space (a few times the size of the array or more).

Therefore, in performance-critical code, try to avoid using this method on large arrays or check the emitted code. Also try to avoid chained maps (e.g. arr.map(...).map(...)).

In many cases, you can instead use Iterator::map by calling .iter() or .into_iter() on your array. [T; N]::map is only necessary if you really need a new array of the same size as the result. Rust’s lazy iterators tend to get optimized very well.

Examples

let x = [1, 2, 3];
let y = x.map(|v| v + 1);
assert_eq!(y, [2, 3, 4]);

let x = [1, 2, 3];
let mut temp = 0;
let y = x.map(|v| { temp += 1; v * temp });
assert_eq!(y, [1, 4, 9]);

let x = ["Ferris", "Bueller's", "Day", "Off"];
let y = x.map(|v| v.len());
assert_eq!(y, [6, 9, 3, 3]);

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pub fn try_map<F, R>( self, f: F ) -> <<R as Try>::Residual as Residual<[<R as Try>::Output; N]>>::TryTypewhere F: FnMut(T) -> R, R: Try, <R as Try>::Residual: Residual<[<R as Try>::Output; N]>,

🔬This is a nightly-only experimental API. (array_try_map)

A fallible function f applied to each element on array self in order to return an array the same size as self or the first error encountered.

The return type of this function depends on the return type of the closure. If you return Result<T, E> from the closure, you’ll get a Result<[T; N], E>. If you return Option<T> from the closure, you’ll get an Option<[T; N]>.

Examples

#![feature(array_try_map)]
let a = ["1", "2", "3"];
let b = a.try_map(|v| v.parse::<u32>()).unwrap().map(|v| v + 1);
assert_eq!(b, [2, 3, 4]);

let a = ["1", "2a", "3"];
let b = a.try_map(|v| v.parse::<u32>());
assert!(b.is_err());

use std::num::NonZeroU32;
let z = [1, 2, 0, 3, 4];
assert_eq!(z.try_map(NonZeroU32::new), None);
let a = [1, 2, 3];
let b = a.try_map(NonZeroU32::new);
let c = b.map(|x| x.map(NonZeroU32::get));
assert_eq!(c, Some(a));

1.57.0 (const: 1.57.0) · source

pub const fn as_slice(&self) -> &[T]

Returns a slice containing the entire array. Equivalent to &s[..].

1.57.0 · source

pub fn as_mut_slice(&mut self) -> &mut [T]

Returns a mutable slice containing the entire array. Equivalent to &mut s[..].

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pub fn each_ref(&self) -> [&T; N]

🔬This is a nightly-only experimental API. (array_methods)

Borrows each element and returns an array of references with the same size as self.

Example

#![feature(array_methods)]

let floats = [3.1, 2.7, -1.0];
let float_refs: [&f64; 3] = floats.each_ref();
assert_eq!(float_refs, [&3.1, &2.7, &-1.0]);

This method is particularly useful if combined with other methods, like map. This way, you can avoid moving the original array if its elements are not Copy.

#![feature(array_methods)]

let strings = ["Ferris".to_string(), "♥".to_string(), "Rust".to_string()];
let is_ascii = strings.each_ref().map(|s| s.is_ascii());
assert_eq!(is_ascii, [true, false, true]);

// We can still access the original array: it has not been moved.
assert_eq!(strings.len(), 3);

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pub fn each_mut(&mut self) -> [&mut T; N]

🔬This is a nightly-only experimental API. (array_methods)

Borrows each element mutably and returns an array of mutable references with the same size as self.

Example

#![feature(array_methods)]

let mut floats = [3.1, 2.7, -1.0];
let float_refs: [&mut f64; 3] = floats.each_mut();
*float_refs[0] = 0.0;
assert_eq!(float_refs, [&mut 0.0, &mut 2.7, &mut -1.0]);
assert_eq!(floats, [0.0, 2.7, -1.0]);

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pub fn split_array_ref<const M: usize>(&self) -> (&[T; M], &[T])

🔬This is a nightly-only experimental API. (split_array)

Divides one array reference into two at an index.

The first will contain all indices from [0, M) (excluding the index M itself) and the second will contain all indices from [M, N) (excluding the index N itself).

Panics

Panics if M > N.

Examples

#![feature(split_array)]

let v = [1, 2, 3, 4, 5, 6];

{
   let (left, right) = v.split_array_ref::<0>();
   assert_eq!(left, &[]);
   assert_eq!(right, &[1, 2, 3, 4, 5, 6]);
}

{
    let (left, right) = v.split_array_ref::<2>();
    assert_eq!(left, &[1, 2]);
    assert_eq!(right, &[3, 4, 5, 6]);
}

{
    let (left, right) = v.split_array_ref::<6>();
    assert_eq!(left, &[1, 2, 3, 4, 5, 6]);
    assert_eq!(right, &[]);
}

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pub fn split_array_mut<const M: usize>(&mut self) -> (&mut [T; M], &mut [T])

🔬This is a nightly-only experimental API. (split_array)

Divides one mutable array reference into two at an index.

The first will contain all indices from [0, M) (excluding the index M itself) and the second will contain all indices from [M, N) (excluding the index N itself).

Panics

Panics if M > N.

Examples

#![feature(split_array)]

let mut v = [1, 0, 3, 0, 5, 6];
let (left, right) = v.split_array_mut::<2>();
assert_eq!(left, &mut [1, 0][..]);
assert_eq!(right, &mut [3, 0, 5, 6]);
left[1] = 2;
right[1] = 4;
assert_eq!(v, [1, 2, 3, 4, 5, 6]);

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pub fn rsplit_array_ref<const M: usize>(&self) -> (&[T], &[T; M])

🔬This is a nightly-only experimental API. (split_array)

Divides one array reference into two at an index from the end.

The first will contain all indices from [0, N - M) (excluding the index N - M itself) and the second will contain all indices from [N - M, N) (excluding the index N itself).

Panics

Panics if M > N.

Examples

#![feature(split_array)]

let v = [1, 2, 3, 4, 5, 6];

{
   let (left, right) = v.rsplit_array_ref::<0>();
   assert_eq!(left, &[1, 2, 3, 4, 5, 6]);
   assert_eq!(right, &[]);
}

{
    let (left, right) = v.rsplit_array_ref::<2>();
    assert_eq!(left, &[1, 2, 3, 4]);
    assert_eq!(right, &[5, 6]);
}

{
    let (left, right) = v.rsplit_array_ref::<6>();
    assert_eq!(left, &[]);
    assert_eq!(right, &[1, 2, 3, 4, 5, 6]);
}