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

#[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);

Associated Types

type Output: ?Sized

The returned type after indexing.

Loading content...

Required methods

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

Performs the indexing (container[index]) operation.

Loading content...

Implementations on Foreign Types

impl Index<RangeFull> for CString

type Output = CStr

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

impl Index<RangeFull> for OsString

type Output = OsStr

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

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

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

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

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

impl<'t> Index<usize> for Captures<'t>

Get a group by index.

't is the lifetime of the matched text.

The text can't outlive the Captures object if this method is used, because of how Index is defined (normally a[i] is part of a and can't outlive it); to do that, use get() instead.

Panics

If there is no group at the given index.

type Output = str

fn index(&self, i: usize) -> &str

impl<'t, 'i> Index<&'i str> for Captures<'t>

Get a group by name.

't is the lifetime of the matched text and 'i is the lifetime of the group name (the index).

The text can't outlive the Captures object if this method is used, because of how Index is defined (normally a[i] is part of a and can't outlive it); to do that, use name instead.

Panics

If there is no group named by the given value.

type Output = str

fn index(&'a self, name: &'i str) -> &'a str

impl<'t, 'i> Index<&'i str> for Captures<'t>

Get a group by name.

't is the lifetime of the matched text and 'i is the lifetime of the group name (the index).

The text can't outlive the Captures object if this method is used, because of how Index is defined (normally a[i] is part of a and can't outlive it); to do that, use name instead.

Panics

If there is no group named by the given value.

type Output = [u8]

Important traits for &'_ [u8]

impl<'_> Read for &'_ [u8]impl<'_> Write for &'_ mut [u8]

fn index(&'a self, name: &'i str) -> &'a [u8]

impl<'t> Index<usize> for Captures<'t>

Get a group by index.

't is the lifetime of the matched text.

The text can't outlive the Captures object if this method is used, because of how Index is defined (normally a[i] is part of a and can't outlive it); to do that, use get() instead.

Panics

If there is no group at the given index.

type Output = [u8]

Important traits for &'_ [u8]

impl<'_> Read for &'_ [u8]impl<'_> Write for &'_ mut [u8]

fn index(&self, i: usize) -> &[u8]

Loading content...

Implementors

impl Index<Range<usize>> for String

type Output = str

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

impl Index<RangeFrom<usize>> for String

type Output = str

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

impl Index<RangeFull> for String

type Output = str

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

impl Index<RangeInclusive<usize>> for String

type Output = str

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

impl Index<RangeTo<usize>> for String

type Output = str

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

impl Index<RangeToInclusive<usize>> for String

type Output = str

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

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

type Output = V

Important traits for &'_ mut I

impl<'_, I> Iterator for &'_ mut I where
    I: Iterator + ?Sized,  type Item = <I as Iterator>::Item;

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.

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

type Output = V

Important traits for &'_ mut I

impl<'_, I> Iterator for &'_ mut I where
    I: Iterator + ?Sized,  type Item = <I as Iterator>::Item;

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.

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

type Output = A

Important traits for &'_ mut I

impl<'_, I> Iterator for &'_ mut I where
    I: Iterator + ?Sized,  type Item = <I as Iterator>::Item;

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

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

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

Important traits for Vec<u8>

impl Write for Vec<u8>

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

Loading content...