14 releases
new 0.2.10 | Nov 10, 2024 |
---|---|
0.2.9 | Nov 10, 2024 |
0.2.8 | Oct 3, 2024 |
0.2.7 | Sep 15, 2024 |
0.1.3 | Sep 7, 2024 |
#389 in Data structures
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70KB
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SLoC
This crate can split Vec in half, with the front part being &mut [T]
,
and the back part being able to perform push
, pop
etc
Examples
use tailvec::{TailVec, SplitTail};
let mut vec = vec![1, 2, 3, 4];
vec.reserve_exact(3);
assert_eq!(vec.capacity(), 7);
let (left, mut rest) = vec.split_tail(2);
assert_eq!(left, &mut [1, 2]);
assert_eq!(rest, &mut [3, 4]);
assert_eq!(rest.push(5), Ok(()));
assert_eq!(rest, &mut [3, 4, 5]);
assert_eq!(rest.push(6), Ok(()));
assert_eq!(rest, &mut [3, 4, 5, 6]);
assert_eq!(rest.push(7), Ok(()));
assert_eq!(rest, &mut [3, 4, 5, 6, 7]);
assert_eq!(rest.push(8), Err(8)); // overflow of capacity
assert_eq!(rest, &mut [3, 4, 5, 6, 7]);
assert_eq!(rest.pop(), Some(7));
assert_eq!(rest, &mut [3, 4, 5, 6]);
drop(rest); // drop guard
assert_eq!(vec, [1, 2, 3, 4, 5, 6]);
By using this crate, you can avoid the alloc costs caused by code similar to the following
let mut vec = vec![1, 2, 3, 4];
vec.reserve_exact(3);
assert_eq!(vec.capacity(), 7);
let a = vec.as_ptr();
let mut rest = vec.split_off(2);
assert_eq!(vec, &[1, 2]);
assert_eq!(rest, &[3, 4]);
rest.push(5);
rest.push(6);
rest.push(7);
rest.pop();
assert_eq!(rest, [3, 4, 5, 6]);
assert!(rest.as_ptr() >= a.wrapping_add(vec.capacity()) ||
rest.as_ptr() < a); // allocated a new vec
assert_eq!(vec, [1, 2]);
vec.extend(rest);
assert_eq!(vec, [1, 2, 3, 4, 5, 6]);
assert!(core::ptr::eq(vec.as_ptr(), a));
Safety
- miri has passed