Trait nom::lib::std::ops::Index

#[lang = "index"]
pub trait Index<Idx> where
    Idx: ?Sized, {
    type Output: ?Sized;
    pub 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

type Output: ?Sized[−]

The returned type after indexing.

Required methods

pub fn index(&self, index: Idx) -> &Self::Output[−]

Performs the indexing (container[index]) operation.

Implementors

impl<I> Index<I> for str where
    I: SliceIndex<str>, [+]

[+] Show hidden undocumented items

type Output = <I as SliceIndex<str>>::Output

pub fn index(&self, index: I) -> &<I as SliceIndex<str>>::Output

impl<T, I> Index<I> for [T] where
    I: SliceIndex<[T]>, [+]

[+] Show hidden undocumented items

type Output = <I as SliceIndex<[T]>>::Output

pub fn index(&self, index: I) -> &<I as SliceIndex<[T]>>::Output

impl<T, I, const N: usize> Index<I> for [T; N] where
    [T]: Index<I>, [+]

[+] Show hidden undocumented items

type Output = <[T] as Index<I>>::Output

pub fn index(&self, index: I) -> &<[T; N] as Index<I>>::Output

impl<Buffer> Index<(u8, u32, u32)> for FlatSamples<Buffer> where     Buffer: Index<usize>,

impl<P, Container> Index<(u32, u32)> for ImageBuffer<P, Container> where     P: Pixel + 'static,     P::Subpixel: 'static,     Container: Deref<Target = [P::Subpixel]>,

impl<T: Primitive> Index<usize> for Rgb<T>

impl<T: Primitive> Index<usize> for Bgr<T>

impl<T: Primitive> Index<usize> for Luma<T>

impl<T: Primitive> Index<usize> for Rgba<T>

impl<T: Primitive> Index<usize> for Bgra<T>

impl<T: Primitive> Index<usize> for LumaA<T>

impl<T> Index<usize> for Slab<T>

impl<A: Array, I: SliceIndex<[A::Item]>> Index<I> for SmallVec<A>

impl<T, P> Index<usize> for Punctuated<T, P>

impl Index<usize> for Cursor