Trait cds::LengthType

source · [−]
pub trait LengthType: LengthTypeBase { }
Expand description

A trait of custom length types.

cds fixed capacity collections allow customization of the type used to track the collection length. This allows more compact representation of a collection type, especially when low capacity is required.

Every length-type having N bits in the underlying type supports collections with capacity of up to 2 ^ N - 1 elements.

Currently supported length types are: U8, U16, U32, U64 and Usize.

Examples

LengthType allows creation of very compact fixed-capacity collections:

use cds::{
    arrayvec::ArrayVec,
    defs::{Uninitialized, U8}
};
type A = ArrayVec<u8, U8, Uninitialized, 7>;
assert_eq!(core::mem::size_of::<A>(), 8); // 7 element bytes + 1 length byte

The requested capacity may not exceed the length-type’s maximal value:

ⓘ
use cds::{
    arrayvec::ArrayVec,
    defs::{Uninitialized, U8}
};
type A = ArrayVec<u8, U8, Uninitialized, 256>; // U8::MAX(255) < CAPACITY(256)
let a = A::new();   // <-- this panics

Implementors