Trait enso_prelude::Index

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

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

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

Performs the indexing (container[index]) operation.

Panics

May panic if the index is out of bounds.

Implementations on Foreign Types

impl Index<RangeFull> for OsString

type Output = OsStr

pub fn index(&self, _index: RangeFull) -> &OsStr

impl Index<RangeFull> for CString

type Output = CStr

pub fn index(&self, _index: RangeFull) -> &CStr

impl Index<RangeFrom<usize>> for CStr

type Output = CStr

pub fn index(&self, index: RangeFrom<usize>) -> &CStr

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

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

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

impl<I> Index<I> for str where
    I: SliceIndex<str>, 

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

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

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

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

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

impl Index<RangeFrom<usize>> for String

type Output = str

pub fn index(&self, index: RangeFrom<usize>) -> &str

impl Index<RangeInclusive<usize>> for String

type Output = str

pub fn index(&self, index: RangeInclusive<usize>) -> &str

impl Index<RangeFull> for String

type Output = str

pub fn index(&self, _index: RangeFull) -> &str

impl Index<RangeTo<usize>> for String

type Output = str

pub fn index(&self, index: RangeTo<usize>) -> &str

impl Index<RangeToInclusive<usize>> for String

type Output = str

pub fn index(&self, index: RangeToInclusive<usize>) -> &str

impl Index<Range<usize>> for String

type Output = str

pub fn index(&self, index: Range<usize>) -> &str

impl<T, I, A> Index<I> for Vec<T, A> where
    I: SliceIndex<[T]>,
    A: Allocator, 

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

pub fn index(&self, index: I) -> &<Vec<T, A> as Index<I>>::Output

impl<A> Index<usize> for VecDeque<A>

type Output = A

pub fn index(&self, index: usize) -> &A

impl<'input, Endian> Index<RangeFrom<usize>> for EndianSlice<'input, Endian> where
    Endian: Endianity, 

type Output = [u8]

pub fn index(
    &self,
    idx: RangeFrom<usize>
) -> &<EndianSlice<'input, Endian> as Index<RangeFrom<usize>>>::Output

impl<'input, Endian> Index<usize> for EndianSlice<'input, Endian> where
    Endian: Endianity, 

type Output = u8

pub fn index(
    &self,
    idx: usize
) -> &<EndianSlice<'input, Endian> as Index<usize>>::Output

impl<'a, K, V, S> Index<&'a <K as WeakElement>::Strong> for PtrWeakKeyHashMap<K, V, S> where
    S: BuildHasher,
    K: WeakElement,
    <K as WeakElement>::Strong: Deref, 

type Output = V

pub fn index(
    &self,
    index: &'a <K as WeakElement>::Strong
) -> &<PtrWeakKeyHashMap<K, V, S> as Index<&'a <K as WeakElement>::Strong>>::Output

impl<T, R, C, S> Index<usize> for Matrix<T, R, C, S> where
    C: Dim,
    T: Scalar,
    R: Dim,
    S: Storage<T, R, C>, 

type Output = T

pub fn index(&self, i: usize) -> &<Matrix<T, R, C, S> as Index<usize>>::Output

impl<T> Index<usize> for DualQuaternion<T> where
    T: SimdRealField, 

type Output = T

pub fn index(&self, i: usize) -> &<DualQuaternion<T> as Index<usize>>::Output

impl<T, const D: usize> Index<usize> for Point<T, D> where
    T: Scalar, 

type Output = T

pub fn index(&self, i: usize) -> &<Point<T, D> as Index<usize>>::Output

impl<T, const D: usize> Index<(usize, usize)> for Rotation<T, D> where
    T: Scalar, 

type Output = T

pub fn index(&self, row_col: (usize, usize)) -> &T

impl<T, R, C, S> Index<(usize, usize)> for Matrix<T, R, C, S> where
    C: Dim,
    T: Scalar,
    R: Dim,
    S: Storage<T, R, C>, 

type Output = T

pub fn index(
    &self,
    ij: (usize, usize)
) -> &<Matrix<T, R, C, S> as Index<(usize, usize)>>::Output

impl<T, C, const D: usize> Index<(usize, usize)> for Transform<T, C, D> where
    C: TCategory,
    T: RealField,
    Const<D>: DimNameAdd<Const<1_usize>>,
    DefaultAllocator: Allocator<T, <Const<D> as DimNameAdd<Const<1_usize>>>::Output, <Const<D> as DimNameAdd<Const<1_usize>>>::Output>, 

type Output = T

pub fn index(&self, ij: (usize, usize)) -> &T

impl<T> Index<usize> for Quaternion<T> where
    T: Scalar, 

type Output = T

pub fn index(&self, i: usize) -> &<Quaternion<T> as Index<usize>>::Output

Implementors

impl<'_, K, Q, V> Index<&'_ Q> for BTreeMap<K, V> where
    K: Borrow<Q> + Ord,
    Q: Ord + ?Sized, 

pub fn index(&self, key: &Q) -> &V

Returns a reference to the value corresponding to the supplied key.

Panics

Panics if the key is not present in the BTreeMap.

type Output = V

impl<'_, K, Q, V, S> Index<&'_ Q> for HashMap<K, V, S> where
    S: BuildHasher,
    K: Eq + Hash + Borrow<Q>,
    Q: Eq + Hash + ?Sized, 

pub fn index(&self, key: &Q) -> &V

Returns a reference to the value corresponding to the supplied key.

Panics

Panics if the key is not present in the HashMap.

type Output = V

impl<'a, K, V, S, Q> Index<&'a Q> for WeakKeyHashMap<K, V, S> where
    S: BuildHasher,
    K: WeakKey,
    Q: Eq + Hash + ?Sized,
    <K as WeakKey>::Key: Borrow<Q>, 

type Output = V

pub fn index(
    &self,
    index: &'a Q
) -> &<WeakKeyHashMap<K, V, S> as Index<&'a Q>>::Output

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

type Output = <I as SliceIndex<[<A as Array>::Item]>>::Output

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