std::hash::Hash - Rust
Description: API documentation for the Rust `Hash` trait in crate `std`.
Keywords: rust, rustlang, rust-lang, Hash

# Trait std::hash::Hash 1.0.0 [−] [src]

    pub trait Hash {
        fn hash<H>(&self, state: &mut H)
        where
            H: Hasher;

        fn hash_slice<H>(data: &[Self], state: &mut H)
        where
            H: Hasher,
        { ... }
    }

A hashable type.

Types implementing `Hash` are able to be `hash`ed with an instance of `Hasher`.

## Implementing `Hash`

You can derive `Hash` with `#[derive(Hash)]` if all fields implement `Hash`. The resulting hash will be the combination of the values from calling `hash` on each field.

    #[derive(Hash)]
    struct Rustacean {
        name: String,
        country: String,
    }Run

If you need more control over how a value is hashed, you can of course implement the `Hash` trait yourself:

    use std::hash::{Hash, Hasher};

    struct Person {
        id: u32,
        name: String,
        phone: u64,
    }

    impl Hash for Person {
        fn hash<H: Hasher>(&self, state: &mut H) {
            self.id.hash(state);
            self.phone.hash(state);
        }
    }Run

## `Hash` and `Eq`

When implementing both `Hash` and `Eq`, it is important that the following property holds:

    k1 == k2 -> hash(k1) == hash(k2)

In other words, if two keys are equal, their hashes must also be equal. `HashMap` and `HashSet` both rely on this behavior.

Thankfully, you won't need to worry about upholding this property when deriving both `Eq` and `Hash` with `#[derive(PartialEq, Eq, Hash)]`.

## Required Methods

### `fn hash<H>(&self, state: &mut H) where
H: Hasher,`

Feeds this value into the given `Hasher`.

# Examples

    use std::collections::hash_map::DefaultHasher;
    use std::hash::{Hash, Hasher};

    let mut hasher = DefaultHasher::new();
    7920.hash(&mut hasher);
    println!("Hash is {:x}!", hasher.finish());Run

## Provided Methods

### `fn hash_slice<H>(data: &[Self], state: &mut H) where
H: Hasher,`
1.3.0

Feeds a slice of this type into the given `Hasher`.

# Examples

    use std::collections::hash_map::DefaultHasher;
    use std::hash::{Hash, Hasher};

    let mut hasher = DefaultHasher::new();
    let numbers = [6, 28, 496, 8128];
    Hash::hash_slice(&numbers, &mut hasher);
    println!("Hash is {:x}!", hasher.finish());Run

## Implementors

- `impl<Ret, A, B> Hash for unsafe extern "C" fn(A, B) -> Ret`
- `impl<T> Hash for [T; 15] where
  T: Hash,`
- `impl<Ret, A, B, C, D, E, F, G, H, I, J, K, L> Hash for unsafe extern "C" fn(A, B, C, D, E, F, G, H, I, J, K, L) -> Ret`
- `impl<Idx> Hash for RangeFrom<Idx> where
  Idx: Hash,`
- `impl<Ret, A, B, C, D, E, F, G, H> Hash for fn(A, B, C, D, E, F, G, H) -> Ret`
- `impl<T> Hash for [T; 0] where
  T: Hash,`
- `impl Hash for i128`
- `impl<Ret, A, B, C, D, E, F, G, H> Hash for extern "C" fn(A, B, C, D, E, F, G, H) -> Ret`
- `impl<T> Hash for [T; 19] where
  T: Hash,`
- `impl<T> Hash for [T; 22] where
  T: Hash,`
- `impl<Ret, A, B, C, D, E, F, G, H, I, J> Hash for unsafe extern "C" fn(A, B, C, D, E, F, G, H, I, J, ...) -> Ret`
- `impl<T> Hash for [T; 21] where
  T: Hash,`
- `impl<T> Hash for [T; 3] where
  T: Hash,`
- `impl<Ret, A, B, C, D, E, F, G, H, I, J> Hash for extern "C" fn(A, B, C, D, E, F, G, H, I, J) -> Ret`
- `impl<T> Hash for [T; 12] where
  T: Hash,`
- `impl<T> Hash for [T; 16] where
  T: Hash,`
- `impl<T> Hash for [T; 27] where
  T: Hash,`
- `impl<Ret, A, B, C, D, E, F, G, H, I> Hash for extern "C" fn(A, B, C, D, E, F, G, H, I, ...) -> Ret`
- `impl Hash for i32`
- `impl<Ret, A, B, C, D, E> Hash for unsafe extern "C" fn(A, B, C, D, E, ...) -> Ret`
- `impl<Ret, A, B, C, D, E> Hash for unsafe fn(A, B, C, D, E) -> Ret`
- `impl<T> Hash for *mut T`
- `impl Hash for i64`
- `impl<Ret, A, B, C, D, E, F, G, H> Hash for unsafe extern "C" fn(A, B, C, D, E, F, G, H, ...) -> Ret`
- `impl<Ret, A, B, C> Hash for extern "C" fn(A, B, C) -> Ret`
- `impl Hash for Error`
- `impl<T> Hash for [T; 9] where
  T: Hash,`
- `impl Hash for str`
- `impl<Ret, A, B, C, D, E, F, G, H, I, J, K, L> Hash for extern "C" fn(A, B, C, D, E, F, G, H, I, J, K, L) -> Ret`
- `impl<Idx> Hash for RangeTo<Idx> where
  Idx: Hash,`
- `impl<T> Hash for [T; 6] where
  T: Hash,`
- `impl<A, B, C, D, E, F> Hash for (A, B, C, D, E, F) where
  A: Hash,
  B: Hash,
  C: Hash,
  D: Hash,
  E: Hash,
  F: Hash + ?Sized,`
- `impl Hash for ()`
- `impl<Ret, A, B, C, D, E, F> Hash for extern "C" fn(A, B, C, D, E, F) -> Ret`
- `impl<Ret, A, B, C, D, E, F, G, H, I> Hash for extern "C" fn(A, B, C, D, E, F, G, H, I) -> Ret`
- `impl<Ret, A, B, C, D, E, F, G, H, I, J, K> Hash for unsafe extern "C" fn(A, B, C, D, E, F, G, H, I, J, K, ...) -> Ret`
- `impl<T> Hash for [T; 10] where
  T: Hash,`
- `impl<A, B, C> Hash for (A, B, C) where
  A: Hash,
  B: Hash,
  C: Hash + ?Sized,`
- `impl<A, B, C, D, E, F, G> Hash for (A, B, C, D, E, F, G) where
  A: Hash,
  B: Hash,
  C: Hash,
  D: Hash,
  E: Hash,
  F: Hash,
  G: Hash + ?Sized,`
- `impl<T> Hash for [T; 13] where
  T: Hash,`
- `impl<T> Hash for [T; 24] where
  T: Hash,`
- `impl<Ret, A, B, C, D, E, F, G> Hash for unsafe fn(A, B, C, D, E, F, G) -> Ret`
- `impl Hash for RangeFull`
- `impl<T> Hash for Discriminant<T>`
- `impl<Ret, A> Hash for unsafe fn(A) -> Ret`
- `impl<Ret, A, B, C, D, E, F, G> Hash for unsafe extern "C" fn(A, B, C, D, E, F, G, ...) -> Ret`
- `impl<Ret, A, B, C, D, E, F, G, H, I, J> Hash for unsafe extern "C" fn(A, B, C, D, E, F, G, H, I, J) -> Ret`
- `impl<Ret, A, B, C, D, E, F, G> Hash for fn(A, B, C, D, E, F, G) -> Ret`
- `impl<Ret, A, B, C, D, E, F> Hash for unsafe fn(A, B, C, D, E, F) -> Ret`
- `impl<T> Hash for [T] where
  T: Hash,`
- `impl<'a, T> Hash for &'a mut T where
  T: Hash + ?Sized,`
- `impl<Ret, A, B, C, D, E, F, G, H, I, J, K, L> Hash for extern "C" fn(A, B, C, D, E, F, G, H, I, J, K, L, ...) -> Ret`
- `impl<A, B, C, D, E, F, G, H, I, J> Hash for (A, B, C, D, E, F, G, H, I, J) where
  A: Hash,
  B: Hash,
  C: Hash,
  D: Hash,
  E: Hash,
  F: Hash,
  G: Hash,
  H: Hash,
  I: Hash,
  J: Hash + ?Sized,`
- `impl<Ret, A, B, C, D, E, F, G, H, I, J, K> Hash for extern "C" fn(A, B, C, D, E, F, G, H, I, J, K, ...) -> Ret`
- `impl<Idx> Hash for Range<Idx> where
  Idx: Hash,`
- `impl<Ret, A, B, C, D, E, F, G> Hash for extern "C" fn(A, B, C, D, E, F, G) -> Ret`
- `impl<Ret, A, B, C, D, E, F> Hash for fn(A, B, C, D, E, F) -> Ret`
- `impl<Ret, A> Hash for extern "C" fn(A) -> Ret`
- `impl<Ret, A, B, C, D, E, F, G, H, I> Hash for fn(A, B, C, D, E, F, G, H, I) -> Ret`
- `impl<Idx> Hash for RangeInclusive<Idx> where
  Idx: Hash,`
- `impl<Ret, A, B, C, D> Hash for extern "C" fn(A, B, C, D, ...) -> Ret`
- `impl Hash for i8`
- `impl<Ret, A, B> Hash for unsafe fn(A, B) -> Ret`
- `impl<Ret, A, B, C, D, E, F, G, H> Hash for extern "C" fn(A, B, C, D, E, F, G, H, ...) -> Ret`
- `impl<A, B, C, D, E> Hash for (A, B, C, D, E) where
  A: Hash,
  B: Hash,
  C: Hash,
  D: Hash,
  E: Hash + ?Sized,`
- `impl<A, B, C, D> Hash for (A, B, C, D) where
  A: Hash,
  B: Hash,
  C: Hash,
  D: Hash + ?Sized,`
- `impl<Ret, A, B, C, D, E, F> Hash for extern "C" fn(A, B, C, D, E, F, ...) -> Ret`
- `impl Hash for i16`
- `impl<T> Hash for NonZero<T> where
  T: Zeroable + Hash,`
- `impl<Ret> Hash for unsafe fn() -> Ret`
- `impl<A> Hash for (A,) where
  A: Hash + ?Sized,`
- `impl<T> Hash for [T; 5] where
  T: Hash,`
- `impl<Ret, A, B, C, D> Hash for extern "C" fn(A, B, C, D) -> Ret`
- `impl Hash for u64`
- `impl<T> Hash for [T; 14] where
  T: Hash,`
- `impl<Ret, A, B> Hash for extern "C" fn(A, B) -> Ret`
- `impl<Ret, A, B, C, D, E, F, G, H, I, J, K, L> Hash for unsafe extern "C" fn(A, B, C, D, E, F, G, H, I, J, K, L, ...) -> Ret`
- `impl<T> Hash for [T; 26] where
  T: Hash,`
- `impl<Ret, A, B, C> Hash for unsafe extern "C" fn(A, B, C, ...) -> Ret`
- `impl<Ret, A, B, C, D> Hash for fn(A, B, C, D) -> Ret`
- `impl<Idx> Hash for RangeToInclusive<Idx> where
  Idx: Hash,`
- `impl<Ret, A, B, C, D, E, F, G, H, I, J> Hash for fn(A, B, C, D, E, F, G, H, I, J) -> Ret`
- `impl<T> Hash for [T; 29] where
  T: Hash,`
- `impl<Ret, A> Hash for extern "C" fn(A, ...) -> Ret`
- `impl<T> Hash for [T; 32] where
  T: Hash,`
- `impl<Ret, A, B, C, D, E, F, G, H> Hash for unsafe fn(A, B, C, D, E, F, G, H) -> Ret`
- `impl<Ret, A> Hash for unsafe extern "C" fn(A) -> Ret`
- `impl<Ret, A, B, C, D, E, F, G, H> Hash for unsafe extern "C" fn(A, B, C, D, E, F, G, H) -> Ret`
- `impl Hash for usize`
- `impl Hash for u8`
- `impl<Ret, A, B, C, D, E, F, G, H, I> Hash for unsafe fn(A, B, C, D, E, F, G, H, I) -> Ret`
- `impl<T> Hash for [T; 8] where
  T: Hash,`
- `impl<Ret, A, B, C, D, E, F, G, H, I, J, K> Hash for extern "C" fn(A, B, C, D, E, F, G, H, I, J, K) -> Ret`
- `impl<Ret, A, B, C, D, E, F> Hash for unsafe extern "C" fn(A, B, C, D, E, F, ...) -> Ret`
- `impl Hash for bool`
- `impl Hash for char`
- `impl<T> Hash for Option<T> where
  T: Hash,`
- `impl<A, B, C, D, E, F, G, H, I, J, K> Hash for (A, B, C, D, E, F, G, H, I, J, K) where
  A: Hash,
  B: Hash,
  C: Hash,
  D: Hash,
  E: Hash,
  F: Hash,
  G: Hash,
  H: Hash,
  I: Hash,
  J: Hash,
  K: Hash + ?Sized,`
- `impl<A, B, C, D, E, F, G, H, I> Hash for (A, B, C, D, E, F, G, H, I) where
  A: Hash,
  B: Hash,
  C: Hash,
  D: Hash,
  E: Hash,
  F: Hash,
  G: Hash,
  H: Hash,
  I: Hash + ?Sized,`
- `impl<Ret> Hash for unsafe extern "C" fn() -> Ret`
- `impl<Ret, A, B, C, D, E, F, G, H, I, J, K, L> Hash for unsafe fn(A, B, C, D, E, F, G, H, I, J, K, L) -> Ret`
- `impl<T> Hash for [T; 18] where
  T: Hash,`
- `impl<Ret, A, B, C, D, E, F, G> Hash for unsafe extern "C" fn(A, B, C, D, E, F, G) -> Ret`
- `impl Hash for TypeId`
- `impl<T> Hash for [T; 7] where
  T: Hash,`
- `impl<Ret, A, B, C, D, E, F> Hash for unsafe extern "C" fn(A, B, C, D, E, F) -> Ret`
- `impl<A, B> Hash for (A, B) where
  A: Hash,
  B: Hash + ?Sized,`
- `impl<Ret, A, B, C, D, E, F, G, H, I, J, K> Hash for fn(A, B, C, D, E, F, G, H, I, J, K) -> Ret`
- `impl Hash for Ordering`
- `impl<Ret, A, B, C, D, E> Hash for fn(A, B, C, D, E) -> Ret`
- `impl<A, B, C, D, E, F, G, H, I, J, K, L> Hash for (A, B, C, D, E, F, G, H, I, J, K, L) where
  A: Hash,
  B: Hash,
  C: Hash,
  D: Hash,
  E: Hash,
  F: Hash,
  G: Hash,
  H: Hash,
  I: Hash,
  J: Hash,
  K: Hash,
  L: Hash + ?Sized,`
- `impl<T> Hash for [T; 1] where
  T: Hash,`
- `impl<Ret, A> Hash for fn(A) -> Ret`
- `impl<Ret, A, B> Hash for unsafe extern "C" fn(A, B, ...) -> Ret`
- `impl Hash for u128`
- `impl<T, E> Hash for Result<T, E> where
  E: Hash,
  T: Hash,`
- `impl<Ret, A, B> Hash for fn(A, B) -> Ret`
- `impl<T> Hash for [T; 30] where
  T: Hash,`
- `impl<Ret, A> Hash for unsafe extern "C" fn(A, ...) -> Ret`
- `impl<Ret, A, B, C, D> Hash for unsafe extern "C" fn(A, B, C, D) -> Ret`
- `impl<T> Hash for *const T`
- `impl<T> Hash for PhantomData<T> where
  T: ?Sized,`
- `impl<T> Hash for [T; 20] where
  T: Hash,`
- `impl<Ret, A, B, C, D, E, F, G, H, I> Hash for unsafe extern "C" fn(A, B, C, D, E, F, G, H, I) -> Ret`
- `impl<Ret, A, B, C, D> Hash for unsafe extern "C" fn(A, B, C, D, ...) -> Ret`
- `impl<Ret, A, B, C, D, E> Hash for extern "C" fn(A, B, C, D, E, ...) -> Ret`
- `impl<Ret, A, B, C, D, E, F, G, H, I, J> Hash for unsafe fn(A, B, C, D, E, F, G, H, I, J) -> Ret`
- `impl<T> Hash for [T; 28] where
  T: Hash,`
- `impl Hash for isize`
- `impl<Ret, A, B> Hash for extern "C" fn(A, B, ...) -> Ret`
- `impl<A, B, C, D, E, F, G, H> Hash for (A, B, C, D, E, F, G, H) where
  A: Hash,
  B: Hash,
  C: Hash,
  D: Hash,
  E: Hash,
  F: Hash,
  G: Hash,
  H: Hash + ?Sized,`
- `impl<T> Hash for Wrapping<T> where
  T: Hash,`
- `impl<Ret, A, B, C, D, E, F, G, H, I, J> Hash for extern "C" fn(A, B, C, D, E, F, G, H, I, J, ...) -> Ret`
- `impl<Ret, A, B, C, D, E, F, G> Hash for extern "C" fn(A, B, C, D, E, F, G, ...) -> Ret`
- `impl<Ret, A, B, C> Hash for unsafe extern "C" fn(A, B, C) -> Ret`
- `impl<T> Hash for [T; 25] where
  T: Hash,`
- `impl<Ret, A, B, C, D, E, F, G, H, I, J, K> Hash for unsafe extern "C" fn(A, B, C, D, E, F, G, H, I, J, K) -> Ret`
- `impl<Ret, A, B, C> Hash for unsafe fn(A, B, C) -> Ret`
- `impl<Ret> Hash for fn() -> Ret`
- `impl<T> Hash for [T; 2] where
  T: Hash,`
- `impl<T> Hash for [T; 17] where
  T: Hash,`
- `impl<T> Hash for [T; 31] where
  T: Hash,`
- `impl<T> Hash for [T; 23] where
  T: Hash,`
- `impl<T> Hash for [T; 4] where
  T: Hash,`
- `impl<'a, T> Hash for &'a T where
  T: Hash + ?Sized,`
- `impl Hash for u32`
- `impl<Ret, A, B, C, D, E> Hash for unsafe extern "C" fn(A, B, C, D, E) -> Ret`
- `impl Hash for u16`
- `impl<Ret, A, B, C, D, E> Hash for extern "C" fn(A, B, C, D, E) -> Ret`
- `impl<Ret, A, B, C> Hash for extern "C" fn(A, B, C, ...) -> Ret`
- `impl<Ret, A, B, C, D, E, F, G, H, I, J, K, L> Hash for fn(A, B, C, D, E, F, G, H, I, J, K, L) -> Ret`
- `impl<Ret, A, B, C> Hash for fn(A, B, C) -> Ret`
- `impl<Ret, A, B, C, D, E, F, G, H, I, J, K> Hash for unsafe fn(A, B, C, D, E, F, G, H, I, J, K) -> Ret`
- `impl<Ret, A, B, C, D> Hash for unsafe fn(A, B, C, D) -> Ret`
- `impl<T> Hash for [T; 11] where
  T: Hash,`
- `impl<Ret, A, B, C, D, E, F, G, H, I> Hash for unsafe extern "C" fn(A, B, C, D, E, F, G, H, I, ...) -> Ret`
- `impl<Ret> Hash for extern "C" fn() -> Ret`
- `impl<T> Hash for Rc<T> where
  T: Hash + ?Sized,`
- `impl<T> Hash for Bound<T> where
  T: Hash,`
- `impl<A> Hash for VecDeque<A> where
  A: Hash,`
- `impl<K, V> Hash for BTreeMap<K, V> where
  K: Hash,
  V: Hash,`
- `impl<'a, B> Hash for Cow<'a, B> where
  B: Hash + ToOwned + ?Sized,`
- `impl<T> Hash for LinkedList<T> where
  T: Hash,`
- `impl<T> Hash for BTreeSet<T> where
  T: Hash,`
- `impl<T> Hash for Arc<T> where
  T: Hash + ?Sized,`
- `impl Hash for String`
- `impl<T> Hash for Vec<T> where
  T: Hash,`
- `impl<T> Hash for Box<T> where
  T: Hash + ?Sized,`
- `impl Hash for ThreadId`
- `impl Hash for CString`
- `impl Hash for CStr`
- `impl Hash for OsString`
- `impl Hash for OsStr`
- `impl Hash for FileType`
- `impl Hash for ErrorKind`
- `impl Hash for IpAddr`
- `impl Hash for Ipv6MulticastScope`
- `impl Hash for Ipv4Addr`
- `impl Hash for Ipv6Addr`
- `impl Hash for SocketAddr`
- `impl Hash for SocketAddrV4`
- `impl Hash for SocketAddrV6`
- `impl<'a> Hash for Prefix<'a>`
- `impl<'a> Hash for PrefixComponent<'a>`
- `impl<'a> Hash for Component<'a>`
- `impl Hash for PathBuf`
- `impl Hash for Path`
- `impl Hash for Duration`

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