A trait for indexing operations (container[index]) where the input type is not modified. container[index] is syntactic sugar for container.index(index).

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Signature

pub trait IndexView

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Examples

The following example implements IndexView on a NucleotideCount container, which can be indexed without modifying the input, enabling individual counts to be retrieved with index syntax. 
use core::ops::IndexView;

#[derive(Copy, Drop)]
enum Nucleotide {
     A,
     C,
     G,
     T,
 }

#[derive(Copy, Drop)]
struct NucleotideCount {
     a: usize,
     c: usize,
     g: usize,
     t: usize,
 }

impl NucleotideIndex of IndexView {
     type Target = usize;

     fn index(self: @NucleotideCount, index: Nucleotide) -> Self::Target {
         match index {
             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!(nucleotide_count[Nucleotide::A] == 14);
assert!(nucleotide_count[Nucleotide::C] == 9);
assert!(nucleotide_count[Nucleotide::G] == 10);
assert!(nucleotide_count[Nucleotide::T] == 12);

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Trait functions

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index

Performs the indexing (container[index]) operation.

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Panics

May panic if the index is out of bounds.

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Signature

fn index(self: @C, index: I) -> IndexViewTarget

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Trait types

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Target

The returned type after indexing.

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Signature

type Target;