Crate generic_arrayvec

This crate provides interop between the arrayvec and generic_array crates, allowing you to use generic_array’s GenericArray as the backing storage for the data structures in arrayvec. This lets you have vector and string types that store their contents inline, with a capacity that can be referred to in generic code.

Usage

This crate exposes the type aliases GenericArrayVecs and GenericArrayString, which are aliases of datatypes in the arrayvec crate. See the ArrayVec and ArrayString docs to learn about their functionality. Each one also has a corresponding extension trait GenericArrayVecExt and GenericArrayStringExt that provide additional constructors and conversions.

Example

use generic_arrayvec::arrayvec::Array;
use generic_arrayvec::typenum::{Prod, U2, U4};
use generic_arrayvec::{ArrayvecStorage, Capacity, GenericArrayVec};
use std::ops::Mul;

fn main() {
    // Create a vector of `u8`s with a capacity of 4.
    let mut arr = GenericArrayVec::<u8, U4>::new();
    assert_eq!(arr.capacity(), 4);

    // Add some elements to it.
    arr.push(1);
    arr.push(2);
    arr.push(3);
    assert_eq!(&arr[..], &[1, 2, 3]);

    // To demonstrate generic bounds, we call our `double()` function, which is defined below.
    // This function returns a new vector with double the capacity of the input vector.
    // The new vector contains two copies of the input vector's items.
    let doubled = double(&arr);
    assert_eq!(&doubled[..], &[1, 2, 3, 1, 2, 3]);
    assert_eq!(doubled.capacity(), 8);
}

fn double<N>(original: &GenericArrayVec<u8, N>) -> GenericArrayVec<u8, Prod<N, U2>>
where
    // Boilerplate bounds for the input array.
    N: Capacity<u8>,
    ArrayvecStorage<u8, N>: Array<Item = u8>,

    // Boilerplate bounds for the output array. Note it's the same as above, but
    // `N` -> `Prod<N, U2>`.
    Prod<N, U2>: Capacity<u8>,
    ArrayvecStorage<u8, Prod<N, U2>>: Array<Item = u8>,

    N: Mul<U2>,
{
    let mut new = GenericArrayVec::<u8, Prod<N, U2>>::new();

    // These `unwrap()`s can never fail.
    new.try_extend_from_slice(original.as_slice()).unwrap();
    new.try_extend_from_slice(original.as_slice()).unwrap();

    new
}

where bound boilerplate

When working with a GenericArrayVec<T, N> where T and/or N are not concrete types, you will need to always include certain bounds in your where clauses, or you will get a compile error. This dummy function shows how to specify them:

use generic_arrayvec::arrayvec::Array;
use generic_arrayvec::{ArrayvecStorage, Capacity, GenericArrayVec};

fn f<T, N>(_arr: GenericArrayVec<T, N>)
where
    N: Capacity<T>,
    ArrayvecStorage<T, N>: Array<Item = T>,
{
}

And this is how you specify them for GenericArrayString<N>:

use generic_arrayvec::arrayvec::Array;
use generic_arrayvec::{ArrayvecStorage, Capacity, GenericArrayString};

fn f<N>(_arr: GenericArrayString<N>)
where
    N: Capacity<u8>,
    N::ArrayType: Copy,
    ArrayvecStorage<u8, N>: Array<Item = u8>,
{
}

Re-exports

pub use arrayvec;

pub use generic_array;

pub use generic_array::typenum;

Modules

plumbing

Low-level implementation details you shouldn’t need to touch.

Traits

Capacity

A trait implemented by typenum’s unsigned integers, which lets them be used to define the capacity of GenericArrayVec/GenericArrayString.

GenericArrayStringExt

Extension trait for GenericArrayString.

GenericArrayVecExt

Extension trait for GenericArrayVec.

Type Definitions

ArrayvecStorage

A wrapper around a GenericArray that implements the Array trait from the arrayvec crate, allowing it to be used as the backing store for ArrayVec and ArrayString.

GenericArrayString

A GenericArray-backed ArrayString.

GenericArrayVec

A GenericArray-backed ArrayVec.