Trait Indexing

Source

pub trait Indexing<T, E> {
    // Required methods
    fn get_at<'a>(&self, root: &'a T, idx: usize) -> &'a E;
    fn get_mut_at<'a>(&self, root: &'a mut T, idx: usize) -> &'a mut E;
    fn set_at(&self, root: &mut T, idx: usize, value: E);
    fn set_mut_at(&self, root: &mut T, idx: usize, f: impl FnOnce(&mut E));
    fn set_clone_at(&self, root: &mut T, idx: usize, value: &E)
       where E: Clone;
}

Expand description

Indexing operations for accessors that focus Vec<E>.

Provided as a blanket impl for Accessor<T, Vec<E>>.

Required Methods§

Source

fn get_at<'a>(&self, root: &'a T, idx: usize) -> &'a E

Borrow the element at idx immutably.

use pathmod_core::{Accessor, Indexing};
#[derive(Debug)]
struct Bag { items: Vec<i32> }
fn acc_items() -> Accessor<Bag, Vec<i32>> {
    fn gr(b: &Bag) -> &Vec<i32> { &b.items }
    fn gm(b: &mut Bag) -> &mut Vec<i32> { &mut b.items }
    Accessor::from_fns(gr, gm)
}
let b = Bag { items: vec![1,2,3] };
let acc = acc_items();
assert_eq!(*acc.get_at(&b, 1), 2);