Trait core::ops::IndexUnstable

pub trait Index<Index: ?Sized> {
    type Output: ?Sized;

    fn index<'a>(&'a self, index: &Index) -> &'a Output;
}

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

Example

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

#![feature(associated_types)] use std::ops::Index; #[derive(Copy)] struct Foo; impl Index<Foo> for Foo { type Output = Foo; fn index<'a>(&'a self, _index: &Foo) -> &'a Foo { println!("Indexing!"); self } } fn main() { Foo[Foo]; }

#![feature(associated_types)]

use std::ops::Index;

#[derive(Copy)]
struct Foo;

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

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

fn main() {
    Foo[Foo];
}

Associated Types

type Output: ?Sized

Required Methods

fn index<'a>(&'a self, index: &Index) -> &'a 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<FullRange> for [T]
• impl<'a, T> Index<Range<usize>> for Iter<'a, T>
• impl<'a, T> Index<RangeTo<usize>> for Iter<'a, T>
• impl<'a, T> Index<RangeFrom<usize>> for Iter<'a, T>
• impl<'a, T> Index<FullRange> for Iter<'a, T>
• impl<'a, T> Index<Range<usize>> for IterMut<'a, T>
• impl<'a, T> Index<RangeTo<usize>> for IterMut<'a, T>
• impl<'a, T> Index<RangeFrom<usize>> for IterMut<'a, T>
• impl<'a, T> Index<FullRange> for IterMut<'a, T>
• impl Index<Range<usize>> for str
• impl Index<RangeTo<usize>> for str
• impl Index<RangeFrom<usize>> for str
• impl Index<FullRange> for str