Trait len_trait::len::LenMut [−] [src]

pub trait LenMut: Default + Clear {
    fn truncate(&mut self, len: usize);

    fn split_off(&mut self, index: usize) -> Self;
}

A trait for modifying the length of a collection.

These methods must take at most a linear amount of time and space with respect to the number of elements which are moved or dropped.

Required Methods

Truncates the collection to be no greater than len long, dropping elements as needed.

If the collection is less than len long, do nothing.

Panics

Panics if len is not valid according to the collection. For example, the implementation for String will panic if len does not lie on a character boundary.

Examples

use len_trait::LenMut;

fn check_truncate<C: LenMut>(mut collection: C) {
    let old_len = collection.len();
    collection.truncate(5);
    if old_len >= 5 {
        assert_eq!(collection.len(), 5);
    } else {
        assert_eq!(collection.len(), old_len);
    }
}

check_truncate("Hello, world!".to_string());
check_truncate(vec![1, 2, 3]);

Splits off the collection at the given index, returning the data past the index.

Panics

Panics if index > len.

Examples

use len_trait::LenMut;

fn check_split_off<C: LenMut>(mut collection: C) {
    let old_len = collection.len();
    let split = collection.split_off(5);
    assert_eq!(collection.len(), 5);
    assert_eq!(split.len(), old_len - 5);
}

check_split_off("Hello, world!".to_string());
check_split_off(vec![1, 2, 3, 4, 5, 6, 7, 8, 9]);

Implementors