Crate generic_array

This crate implements a structure that can be used as a generic array type.

**Requires minimum Rust version of 1.83.0

Documentation on GH Pages may be required to view certain types on foreign crates.

Before Rust 1.51, arrays [T; N] were problematic in that they couldn’t be generic with respect to the length N, so this wouldn’t work:

struct Foo<N> {
    data: [i32; N],
}

Since 1.51, the below syntax is valid:

struct Foo<const N: usize> {
    data: [i32; N],
}

However, the const-generics we have as of writing this are still the minimum-viable product (min_const_generics), so many situations still result in errors, such as this example:

trait Bar {
    const LEN: usize;

    // Error: cannot perform const operation using `Self`
    fn bar(&self) -> Foo<{ Self::LEN }>;
}

generic-array defines a new trait ArrayLength and a struct GenericArray<T, N: ArrayLength>, which lets the above be implemented as:

use generic_array::{GenericArray, ArrayLength};

struct Foo<N: ArrayLength> {
    data: GenericArray<i32, N>
}

trait Bar {
    type LEN: ArrayLength;
    fn bar(&self) -> Foo<Self::LEN>;
}

The ArrayLength trait is implemented for unsigned integer types from typenum. For example, GenericArray<T, U5> would work almost like [T; 5]:

use generic_array::typenum::U5;

struct Foo<T, N: ArrayLength> {
    data: GenericArray<T, N>
}

let foo = Foo::<i32, U5> { data: GenericArray::default() };

The arr! macro is provided to allow easier creation of literal arrays, as shown below:

let array = arr![1, 2, 3];
//  array: GenericArray<i32, typenum::U3>
assert_eq!(array[2], 3);

Feature flags

[dependencies.generic-array]
features = [
    "serde",         # Serialize/Deserialize implementation
    "zeroize",       # Zeroize implementation for setting array elements to zero
    "const-default", # Compile-time const default value support via trait
    "alloc",         # Enables From/TryFrom implementations between GenericArray and Vec<T>/Box<[T]>
    "faster-hex"     # Enables internal use of the `faster-hex` crate for faster hex encoding via SIMD
]

Re-exports

pub extern crate typenum;

Modules

functional

Functional programming with generic sequences

sequence

Useful traits for manipulating sequences of data stored in GenericArrays

Macros

arr

Macro allowing for easy construction of Generic Arrays.

Structs

GenericArray

Struct representing a generic array - GenericArray<T, N> works like [T; N]

GenericArrayIter

An iterator that moves out of a GenericArray

LengthError

Error for TryFrom and try_from_iter

Traits

ArrayLength

Trait used to define the number of elements in a GenericArray.

IntoArrayLength

Implemented for types which can have an associated ArrayLength, such as Const<N> for use with const-generics.

Type Aliases

ConstArrayLength

Associated ArrayLength for one Const<N>