pub trait Index<Idx> where
Idx: ?Sized, {
type Output: ?Sized;
fn index(&self, index: Idx) -> &Self::Output;
}Expand description
Used for indexing operations (container[index]) in immutable contexts.
container[index] is actually syntactic sugar for *container.index(index),
but only when used as an immutable value. If a mutable value is requested,
IndexMut is used instead. This allows nice things such as
let value = v[index] if the type of value implements Copy.
Examples
The following example implements Index on a read-only NucleotideCount
container, enabling individual counts to be retrieved with index syntax.
use std::ops::Index;
enum Nucleotide {
A,
C,
G,
T,
}
struct NucleotideCount {
a: usize,
c: usize,
g: usize,
t: usize,
}
impl Index<Nucleotide> for NucleotideCount {
type Output = usize;
fn index(&self, nucleotide: Nucleotide) -> &Self::Output {
match nucleotide {
Nucleotide::A => &self.a,
Nucleotide::C => &self.c,
Nucleotide::G => &self.g,
Nucleotide::T => &self.t,
}
}
}
let nucleotide_count = NucleotideCount {a: 14, c: 9, g: 10, t: 12};
assert_eq!(nucleotide_count[Nucleotide::A], 14);
assert_eq!(nucleotide_count[Nucleotide::C], 9);
assert_eq!(nucleotide_count[Nucleotide::G], 10);
assert_eq!(nucleotide_count[Nucleotide::T], 12);Associated Types
Required methods
Implementations on Foreign Types
type Output = <I as SliceIndex<str>>::Output
impl<I, T, const LANES: usize> Index<I> for Simd<T, LANES> where
T: SimdElement,
I: SliceIndex<[T]>,
LaneCount<LANES>: SupportedLaneCount,
impl<I, T, const LANES: usize> Index<I> for Simd<T, LANES> where
T: SimdElement,
I: SliceIndex<[T]>,
LaneCount<LANES>: SupportedLaneCount,
Looks up a single bit by semantic index.
Examples
use bitvec::prelude::*;
let bits = bits![Msb0, u8; 0, 1, 0];
assert!(!bits[0]); // -----^ | |
assert!( bits[1]); // --------^ |
assert!(!bits[2]); // -----------^If the index is greater than or equal to the length, indexing will panic.
The below test will panic when accessing index 1, as only index 0 is valid.
ⓘ
use bitvec::prelude::*;
let bits = bits![0, ];
bits[1]; // --------^