std::hash::Hash

Trait std::hash::Hash

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 hashed 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,
}

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);
    }
}

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

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());

Provided Methods

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());

Implementors

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