Trait wasmer_types::lib::std::ops::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<'_, K, Q, V, S> Index<&'_ Q> for HashMap<K, V, S> where
    K: Eq + Hash + Borrow<Q>,
    S: BuildHasher,
    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 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<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> 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<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<'_, 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<A> Index<usize> for VecDeque<A>

type Output = A

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

impl<K, V, S> Index<usize> for IndexMap<K, V, S>

Access IndexMap values at indexed positions.

Examples

use indexmap::IndexMap;

let mut map = IndexMap::new();
for word in "Lorem ipsum dolor sit amet".split_whitespace() {
    map.insert(word.to_lowercase(), word.to_uppercase());
}
assert_eq!(map[0], "LOREM");
assert_eq!(map[1], "IPSUM");
map.reverse();
assert_eq!(map[0], "AMET");
assert_eq!(map[1], "SIT");
map.sort_keys();
assert_eq!(map[0], "AMET");
assert_eq!(map[1], "DOLOR");

use indexmap::IndexMap;

let mut map = IndexMap::new();
map.insert("foo", 1);
println!("{:?}", map[10]); // panics!

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

Returns a reference to the value at the supplied index.

Panics if index is out of bounds.

type Output = V

impl<T, S> Index<usize> for IndexSet<T, S>

Access IndexSet values at indexed positions.

Examples

use indexmap::IndexSet;

let mut set = IndexSet::new();
for word in "Lorem ipsum dolor sit amet".split_whitespace() {
    set.insert(word.to_string());
}
assert_eq!(set[0], "Lorem");
assert_eq!(set[1], "ipsum");
set.reverse();
assert_eq!(set[0], "amet");
assert_eq!(set[1], "sit");
set.sort();
assert_eq!(set[0], "Lorem");
assert_eq!(set[1], "amet");

use indexmap::IndexSet;

let mut set = IndexSet::new();
set.insert("foo");
println!("{:?}", set[10]); // panics!

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

Returns a reference to the value at the supplied index.

Panics if index is out of bounds.

type Output = T

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

Access IndexMap values corresponding to a key.

Examples

use indexmap::IndexMap;

let mut map = IndexMap::new();
for word in "Lorem ipsum dolor sit amet".split_whitespace() {
    map.insert(word.to_lowercase(), word.to_uppercase());
}
assert_eq!(map["lorem"], "LOREM");
assert_eq!(map["ipsum"], "IPSUM");

use indexmap::IndexMap;

let mut map = IndexMap::new();
map.insert("foo", 1);
println!("{:?}", map["bar"]); // panics!

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

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

Panics if key is not present in the map.

type Output = V

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

type Output = V

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

impl<I> Index<I> for AlignedVec where
    I: SliceIndex<[u8]>, 

type Output = <I as SliceIndex<[u8]>>::Output

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

Implementors

impl Index<Range<usize>> for String

type Output = str

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

impl Index<RangeFrom<usize>> for String

type Output = str

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

impl Index<RangeFull> for String

type Output = str

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

impl Index<RangeInclusive<usize>> for String

type Output = str

pub fn index(&self, index: RangeInclusive<usize>) -> &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<K, V> Index<K> for BoxedSlice<K, V> where
    K: EntityRef, 

Immutable indexing into a BoxedSlice. The indexed value must be in the map.

type Output = V

fn index(&self, k: K) -> &V

impl<K, V> Index<K> for PrimaryMap<K, V> where
    K: EntityRef, 

Immutable indexing into an PrimaryMap. The indexed value must be in the map.

type Output = V

fn index(&self, k: K) -> &V

impl<K, V> Index<K> for SecondaryMap<K, V> where
    K: EntityRef,
    V: Clone, 

Immutable indexing into an SecondaryMap.

All keys are permitted. Untouched entries have the default value.

type Output = V

fn index(&self, k: K) -> &V

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

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

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