1.0.0[][src]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,
}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

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

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 Hash for Ordering
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impl Hash for ErrorKind
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impl Hash for IpAddr
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impl Hash for Ipv6MulticastScope
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impl Hash for SocketAddr
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impl Hash for bool
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impl Hash for char
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impl Hash for i128
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impl Hash for i16
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impl Hash for i32
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impl Hash for i64
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impl Hash for i8
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impl Hash for isize
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impl Hash for !
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impl Hash for str
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impl Hash for u128
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impl Hash for u16
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impl Hash for u32
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impl Hash for u64
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impl Hash for u8
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impl Hash for ()
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impl Hash for usize
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impl Hash for TypeId
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impl Hash for CStr
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impl Hash for CString
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impl Hash for OsStr
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impl Hash for OsString
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impl Hash for Error
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impl Hash for FileType
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impl Hash for PhantomPinned
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impl Hash for Ipv4Addr
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impl Hash for Ipv6Addr
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impl Hash for SocketAddrV4
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impl Hash for SocketAddrV6
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impl Hash for NonZeroU128
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impl Hash for NonZeroU16
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impl Hash for NonZeroU32
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impl Hash for NonZeroU64
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impl Hash for NonZeroU8
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impl Hash for NonZeroUsize
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impl Hash for RangeFull
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impl Hash for NoneError
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impl Hash for Path
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impl Hash for PathBuf
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impl Hash for String
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impl Hash for ThreadId
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impl Hash for Duration
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impl Hash for Instant
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impl Hash for SystemTime
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impl<'_, T> Hash for &'_ T where
    T: Hash + ?Sized
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impl<'_, T> Hash for &'_ mut T where
    T: Hash + ?Sized
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impl<'a> Hash for Component<'a>
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impl<'a> Hash for Prefix<'a>
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impl<'a> Hash for PrefixComponent<'a>
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impl<'a, B> Hash for Cow<'a, B> where
    B: Hash + ToOwned + ?Sized
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impl<A> Hash for (A,) where
    A: Hash + ?Sized
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impl<A> Hash for VecDeque<A> where
    A: Hash
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impl<A, B> Hash for (A, B) where
    A: Hash,
    B: Hash + ?Sized
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impl<A, B, C> Hash for (A, B, C) where
    A: Hash,
    B: Hash,
    C: Hash + ?Sized
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impl<A, B, C, D> Hash for (A, B, C, D) where
    A: Hash,
    B: Hash,
    C: Hash,
    D: Hash + ?Sized
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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
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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
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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
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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
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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
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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
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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
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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
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impl<Idx> Hash for Range<Idx> where
    Idx: Hash
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impl<Idx> Hash for RangeFrom<Idx> where
    Idx: Hash
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impl<Idx> Hash for RangeInclusive<Idx> where
    Idx: Hash
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impl<Idx> Hash for RangeTo<Idx> where
    Idx: Hash
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impl<Idx> Hash for RangeToInclusive<Idx> where
    Idx: Hash
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impl<K, V> Hash for BTreeMap<K, V> where
    K: Hash,
    V: Hash
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impl<P> Hash for Pin<P> where
    P: Hash
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impl<Ret> Hash for fn() -> Ret
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impl<Ret> Hash for extern "C" fn() -> Ret
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impl<Ret> Hash for unsafe fn() -> Ret
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impl<Ret> Hash for unsafe extern "C" fn() -> Ret
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impl<Ret, A> Hash for fn(A) -> Ret
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impl<Ret, A> Hash for extern "C" fn(A) -> Ret
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impl<Ret, A> Hash for extern "C" fn(A, ...) -> Ret
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impl<Ret, A> Hash for unsafe fn(A) -> Ret
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impl<Ret, A> Hash for unsafe extern "C" fn(A) -> Ret
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impl<Ret, A> Hash for unsafe extern "C" fn(A, ...) -> Ret
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impl<Ret, A, B> Hash for fn(A, B) -> Ret
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impl<Ret, A, B> Hash for extern "C" fn(A, B) -> Ret
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impl<Ret, A, B> Hash for extern "C" fn(A, B, ...) -> Ret
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impl<Ret, A, B> Hash for unsafe fn(A, B) -> Ret
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impl<Ret, A, B> Hash for unsafe extern "C" fn(A, B) -> Ret
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impl<Ret, A, B> Hash for unsafe extern "C" fn(A, B, ...) -> Ret
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impl<Ret, A, B, C> Hash for fn(A, B, C) -> Ret
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impl<Ret, A, B, C> Hash for extern "C" fn(A, B, C) -> Ret
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impl<Ret, A, B, C> Hash for extern "C" fn(A, B, C, ...) -> Ret
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impl<Ret, A, B, C> Hash for unsafe fn(A, B, C) -> Ret
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impl<Ret, A, B, C> Hash for unsafe extern "C" fn(A, B, C) -> Ret
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impl<Ret, A, B, C> Hash for unsafe extern "C" fn(A, B, C, ...) -> Ret
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impl<Ret, A, B, C, D> Hash for fn(A, B, C, D) -> Ret
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impl<Ret, A, B, C, D> Hash for extern "C" fn(A, B, C, D) -> Ret
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impl<Ret, A, B, C, D> Hash for extern "C" fn(A, B, C, D, ...) -> Ret
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impl<Ret, A, B, C, D> Hash for unsafe fn(A, B, C, D) -> Ret
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impl<Ret, A, B, C, D> Hash for unsafe extern "C" fn(A, B, C, D) -> Ret
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impl<Ret, A, B, C, D> Hash for unsafe extern "C" fn(A, B, C, D, ...) -> Ret
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impl<Ret, A, B, C, D, E> Hash for fn(A, B, C, D, E) -> Ret
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impl<Ret, A, B, C, D, E> Hash for extern "C" fn(A, B, C, D, E) -> Ret
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impl<Ret, A, B, C, D, E> Hash for extern "C" fn(A, B, C, D, E, ...) -> Ret
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impl<Ret, A, B, C, D, E> Hash for unsafe fn(A, B, C, D, E) -> Ret
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impl<Ret, A, B, C, D, E> Hash for unsafe extern "C" fn(A, B, C, D, E) -> Ret
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impl<Ret, A, B, C, D, E> Hash for unsafe extern "C" fn(A, B, C, D, E, ...) -> Ret
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impl<Ret, A, B, C, D, E, F> Hash for fn(A, B, C, D, E, F) -> Ret
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impl<Ret, A, B, C, D, E, F> Hash for extern "C" fn(A, B, C, D, E, F) -> Ret
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impl<Ret, A, B, C, D, E, F> Hash for extern "C" fn(A, B, C, D, E, F, ...) -> Ret
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impl<Ret, A, B, C, D, E, F> Hash for unsafe fn(A, B, C, D, E, F) -> Ret
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impl<Ret, A, B, C, D, E, F> Hash for unsafe extern "C" fn(A, B, C, D, E, F) -> Ret
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impl<Ret, A, B, C, D, E, F> Hash for unsafe extern "C" fn(A, B, C, D, E, F, ...) -> Ret
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impl<Ret, A, B, C, D, E, F, G> Hash for fn(A, B, C, D, E, F, G) -> Ret
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impl<Ret, A, B, C, D, E, F, G> Hash for extern "C" fn(A, B, C, D, E, F, G) -> Ret
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impl<Ret, A, B, C, D, E, F, G> Hash for extern "C" fn(A, B, C, D, E, F, G, ...) -> Ret
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impl<Ret, A, B, C, D, E, F, G> Hash for unsafe fn(A, B, C, D, E, F, G) -> Ret
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impl<Ret, A, B, C, D, E, F, G> Hash for unsafe extern "C" fn(A, B, C, D, E, F, G) -> Ret
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impl<Ret, A, B, C, D, E, F, G> Hash for unsafe extern "C" fn(A, B, C, D, E, F, G, ...) -> Ret
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impl<Ret, A, B, C, D, E, F, G, H> Hash for fn(A, B, C, D, E, F, G, H) -> Ret
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impl<Ret, A, B, C, D, E, F, G, H> Hash for extern "C" fn(A, B, C, D, E, F, G, H) -> Ret
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impl<Ret, A, B, C, D, E, F, G, H> Hash for extern "C" fn(A, B, C, D, E, F, G, H, ...) -> Ret
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impl<Ret, A, B, C, D, E, F, G, H> Hash for unsafe fn(A, B, C, D, E, F, G, H) -> Ret
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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
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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
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impl<Ret, A, B, C, D, E, F, G, H, I> Hash for fn(A, B, C, D, E, F, G, H, I) -> Ret
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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impl<T> Hash for Bound<T> where
    T: Hash
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impl<T> Hash for Option<T> where
    T: Hash
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impl<T> Hash for Poll<T> where
    T: Hash
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impl<T> Hash for [T; 0] where
    T: Hash
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impl<T> Hash for [T; 1] where
    T: Hash
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impl<T> Hash for [T; 2] where
    T: Hash
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impl<T> Hash for [T; 3] where
    T: Hash
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impl<T> Hash for [T; 4] where
    T: Hash
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impl<T> Hash for [T; 5] where
    T: Hash
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impl<T> Hash for [T; 6] where
    T: Hash
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impl<T> Hash for [T; 7] where
    T: Hash
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impl<T> Hash for [T; 8] where
    T: Hash
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impl<T> Hash for [T; 9] where
    T: Hash
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impl<T> Hash for [T; 10] where
    T: Hash
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impl<T> Hash for [T; 11] where
    T: Hash
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impl<T> Hash for [T; 12] where
    T: Hash
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impl<T> Hash for [T; 13] where
    T: Hash
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impl<T> Hash for [T; 14] where
    T: Hash
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impl<T> Hash for [T; 15] where
    T: Hash
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impl<T> Hash for [T; 16] where
    T: Hash
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impl<T> Hash for [T; 17] where
    T: Hash
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impl<T> Hash for [T; 18] where
    T: Hash
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impl<T> Hash for [T; 19] where
    T: Hash
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impl<T> Hash for [T; 20] where
    T: Hash
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impl<T> Hash for [T; 21] where
    T: Hash
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impl<T> Hash for [T; 22] where
    T: Hash
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impl<T> Hash for [T; 23] where
    T: Hash
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impl<T> Hash for [T; 24] where
    T: Hash
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impl<T> Hash for [T; 25] where
    T: Hash
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impl<T> Hash for [T; 26] where
    T: Hash
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impl<T> Hash for [T; 27] where
    T: Hash
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impl<T> Hash for [T; 28] where
    T: Hash
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impl<T> Hash for [T; 29] where
    T: Hash
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impl<T> Hash for [T; 30] where
    T: Hash
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impl<T> Hash for [T; 31] where
    T: Hash
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impl<T> Hash for [T; 32] where
    T: Hash
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impl<T> Hash for *const T where
    T: ?Sized
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impl<T> Hash for *mut T where
    T: ?Sized
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impl<T> Hash for [T] where
    T: Hash
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impl<T> Hash for Box<T> where
    T: Hash + ?Sized
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impl<T> Hash for Reverse<T> where
    T: Hash
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impl<T> Hash for BTreeSet<T> where
    T: Hash
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impl<T> Hash for LinkedList<T> where
    T: Hash
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impl<T> Hash for PhantomData<T> where
    T: ?Sized
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impl<T> Hash for Discriminant<T>
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impl<T> Hash for ManuallyDrop<T> where
    T: Hash + ?Sized
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impl<T> Hash for Wrapping<T> where
    T: Hash
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impl<T> Hash for NonNull<T> where
    T: ?Sized
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impl<T> Hash for Rc<T> where
    T: Hash + ?Sized
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impl<T> Hash for Arc<T> where
    T: Hash + ?Sized
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impl<T> Hash for Vec<T> where
    T: Hash
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impl<T, E> Hash for Result<T, E> where
    E: Hash,
    T: Hash
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impl<Y, R> Hash for GeneratorState<Y, R> where
    R: Hash,
    Y: Hash
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