Trait std::ops::Index

pub trait Index<Idx> where Idx: ?Sized {
    type Output: ?Sized;
    fn index(&self, index: Idx) -> &Self::Output;
}

The Index trait is used to specify the functionality of indexing operations like arr[idx] when used in an immutable context.

Examples

A trivial implementation of Index. When Foo[Bar] happens, it ends up calling index, and therefore, main prints Indexing!.

use std::ops::Index;

#[derive(Copy, Clone)]
struct Foo;
struct Bar;

impl Index<Bar> for Foo {
    type Output = Foo;

    fn index<'a>(&'a self, _index: Bar) -> &'a Foo {
        println!("Indexing!");
        self
    }
}

fn main() {
    Foo[Bar];
}

Associated Types

type Output: ?Sized

The returned type after indexing

Required Methods

fn index(&self, index: Idx) -> &Self::Output

The method for the indexing (Foo[Bar]) operation

Implementors

• impl<T> Index<usize> for [T]
• impl<T> Index<Range<usize>> for [T]
• impl<T> Index<RangeTo<usize>> for [T]
• impl<T> Index<RangeFrom<usize>> for [T]
• impl<T> Index<RangeFull> for [T]
• impl Index<Range<usize>> for str
• impl Index<RangeTo<usize>> for str
• impl Index<RangeFrom<usize>> for str
• impl Index<RangeFull> for str
• impl<'a, K, Q, V> Index<&'a Q> for BTreeMap<K, V> where K: Ord + Borrow<Q>, Q: Ord + ?Sized
• impl Index<Range<usize>> for String
• impl Index<RangeTo<usize>> for String
• impl Index<RangeFrom<usize>> for String
• impl Index<RangeFull> for String
• impl<T> Index<usize> for Vec<T>
• impl<T> Index<Range<usize>> for Vec<T>
• impl<T> Index<RangeTo<usize>> for Vec<T>
• impl<T> Index<RangeFrom<usize>> for Vec<T>
• impl<T> Index<RangeFull> for Vec<T>
• impl<A> Index<usize> for VecDeque<A>
• impl<'a, K, Q: ?Sized, V, S> Index<&'a Q> for HashMap<K, V, S> where K: Eq + Hash + Borrow<Q>, Q: Eq + Hash, S: HashState