Trait std::ops::Index 1.0.0
[−]
[src]
#[lang = "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) -> &usize { 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);Run
Associated Types
Required Methods
Implementors
impl Index<RangeInclusive<usize>> for str type Output = str;
impl Index<Range<usize>> for str type Output = str;
impl<T, I> Index<I> for [T] where
I: SliceIndex<[T]>, type Output = <I as SliceIndex<[T]>>::Output;impl Index<RangeTo<usize>> for str type Output = str;
impl Index<RangeFull> for str type Output = str;
impl Index<RangeToInclusive<usize>> for str type Output = str;
impl Index<RangeFrom<usize>> for str type Output = str;
impl<T> Index<RangeTo<usize>> for Vec<T> type Output = [T];
impl Index<RangeInclusive<usize>> for String type Output = str;
impl<T> Index<usize> for Vec<T> type Output = T;
impl<T> Index<RangeFull> for Vec<T> type Output = [T];
impl<A> Index<usize> for VecDeque<A> type Output = A;
impl<T> Index<RangeToInclusive<usize>> for Vec<T> type Output = [T];
impl<'a, K, Q, V> Index<&'a Q> for BTreeMap<K, V> where
K: Ord + Borrow<Q>,
Q: Ord + ?Sized, type Output = V;impl Index<Range<usize>> for String type Output = str;
impl<T> Index<Range<usize>> for Vec<T> type Output = [T];
impl<T> Index<RangeInclusive<usize>> for Vec<T> type Output = [T];
impl Index<RangeTo<usize>> for String type Output = str;
impl Index<RangeFull> for String type Output = str;
impl Index<RangeFrom<usize>> for String type Output = str;
impl<T> Index<RangeFrom<usize>> for Vec<T> type Output = [T];
impl Index<RangeToInclusive<usize>> for String type Output = str;
impl<'a, K, Q: ?Sized, V, S> Index<&'a Q> for HashMap<K, V, S> where
K: Eq + Hash + Borrow<Q>,
Q: Eq + Hash,
S: BuildHasher, type Output = V;impl Index<RangeFull> for CString type Output = CStr;
impl Index<RangeFull> for OsString type Output = OsStr;