Trait gstd::prelude::hash::Hash

1.0.0 · source ·
pub trait Hash {
    // Required method
    fn hash<H>(&self, state: &mut H)
       where H: Hasher;

    // Provided method
    fn hash_slice<H>(data: &[Self], state: &mut H)
       where H: Hasher,
             Self: Sized { ... }
}
Expand description

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)].

Violating this property is a logic error. The behavior resulting from a logic error is not specified, but users of the trait must ensure that such logic errors do not result in undefined behavior. This means that unsafe code must not rely on the correctness of these methods.

§Prefix collisions

Implementations of hash should ensure that the data they pass to the Hasher are prefix-free. That is, values which are not equal should cause two different sequences of values to be written, and neither of the two sequences should be a prefix of the other.

For example, the standard implementation of Hash for &str passes an extra 0xFF byte to the Hasher so that the values ("ab", "c") and ("a", "bc") hash differently.

§Portability

Due to differences in endianness and type sizes, data fed by Hash to a Hasher should not be considered portable across platforms. Additionally the data passed by most standard library types should not be considered stable between compiler versions.

This means tests shouldn’t probe hard-coded hash values or data fed to a Hasher and instead should check consistency with Eq.

Serialization formats intended to be portable between platforms or compiler versions should either avoid encoding hashes or only rely on Hash and Hasher implementations that provide additional guarantees.

Required Methods§

source

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

Feeds this value into the given Hasher.

§Examples
use std::hash::{DefaultHasher, Hash, Hasher};

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

Provided Methods§

1.3.0 · source

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

Feeds a slice of this type into the given Hasher.

This method is meant as a convenience, but its implementation is also explicitly left unspecified. It isn’t guaranteed to be equivalent to repeated calls of hash and implementations of Hash should keep that in mind and call hash themselves if the slice isn’t treated as a whole unit in the PartialEq implementation.

For example, a VecDeque implementation might naïvely call as_slices and then hash_slice on each slice, but this is wrong since the two slices can change with a call to make_contiguous without affecting the PartialEq result. Since these slices aren’t treated as singular units, and instead part of a larger deque, this method cannot be used.

§Examples
use std::hash::{DefaultHasher, 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());

Object Safety§

This trait is not object safe.

Implementors§

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impl Hash for ErrorReplyReason

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impl Hash for ExecutionError

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impl Hash for ExtError

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impl Hash for MemoryError

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impl Hash for MessageError

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impl Hash for ReplyCode

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impl Hash for ReservationError

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impl Hash for SignalCode

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impl Hash for SimpleExecutionError

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impl Hash for SimpleProgramCreationError

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impl Hash for SuccessReplyReason

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impl Hash for AsciiChar

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impl Hash for gstd::prelude::cmp::Ordering

1.44.0 · source§

impl Hash for Infallible

1.7.0 · source§

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 core::sync::atomic::Ordering

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impl Hash for ErrorKind

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impl Hash for bool

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impl Hash for char

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impl Hash for i8

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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 i128

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impl Hash for isize

1.29.0 · source§

impl Hash for !

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impl Hash for str

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impl Hash for u8

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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 u128

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impl Hash for ()

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impl Hash for usize

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impl Hash for gstd::ActorId

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impl Hash for gstd::CodeId

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impl Hash for gstd::MessageId

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impl Hash for Reservation

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impl Hash for gstd::ReservationId

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impl Hash for Reservations

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impl Hash for MetaType

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impl Hash for TypeId

1.64.0 · source§

impl Hash for CStr

1.64.0 · source§

impl Hash for CString

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impl Hash for Error

1.33.0 · source§

impl Hash for PhantomPinned

1.34.0 · source§

impl Hash for NonZeroI8

1.34.0 · source§

impl Hash for NonZeroI16

1.34.0 · source§

impl Hash for NonZeroI32

1.34.0 · source§

impl Hash for NonZeroI64

1.34.0 · source§

impl Hash for NonZeroI128

1.34.0 · source§

impl Hash for NonZeroIsize

1.28.0 · source§

impl Hash for NonZeroU8

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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 NonZeroU128

1.28.0 · source§

impl Hash for NonZeroUsize

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impl Hash for RangeFull

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impl Hash for Alignment

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impl Hash for String

1.3.0 · source§

impl Hash for Duration

1.28.0 · source§

impl Hash for Layout

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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 OsStr

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impl Hash for OsString

1.1.0 · source§

impl Hash for FileType

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impl Hash for UCred

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impl Hash for Path

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impl Hash for PathBuf

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impl Hash for PrefixComponent<'_>

1.19.0 · source§

impl Hash for ThreadId

1.8.0 · source§

impl Hash for Instant

1.8.0 · source§

impl Hash for SystemTime

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impl Hash for ActorId

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impl Hash for BigEndian

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impl Hash for Bytes

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impl Hash for BytesMut

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impl Hash for CodeId

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impl Hash for Const

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impl Hash for Dl_info

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impl Hash for Elf32_Chdr

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impl Hash for Elf32_Ehdr

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impl Hash for Elf32_Phdr

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impl Hash for Elf32_Shdr

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impl Hash for Elf32_Sym

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impl Hash for Elf64_Chdr

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impl Hash for Elf64_Ehdr

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impl Hash for Elf64_Phdr

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impl Hash for Elf64_Shdr

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impl Hash for Elf64_Sym

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impl Hash for FromStrRadixErrKind

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impl Hash for H128

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impl Hash for H160

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impl Hash for H256

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impl Hash for H384

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impl Hash for H512

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impl Hash for H768

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impl Hash for LittleEndian

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impl Hash for Lsb0

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impl Hash for MessageId

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impl Hash for Msb0

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impl Hash for Mut

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impl Hash for NullPtrError

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impl Hash for PollNext

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impl Hash for ReservationId

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impl Hash for U128

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impl Hash for U256

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impl Hash for U512

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impl Hash for __c_anonymous_ifru_map

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impl Hash for __c_anonymous_ptrace_syscall_info_data

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impl Hash for __c_anonymous_ptrace_syscall_info_entry

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impl Hash for __c_anonymous_ptrace_syscall_info_exit

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impl Hash for __c_anonymous_ptrace_syscall_info_seccomp

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impl Hash for __c_anonymous_sockaddr_can_j1939

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impl Hash for __c_anonymous_sockaddr_can_tp

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impl Hash for __exit_status

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impl Hash for __timeval

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impl Hash for _libc_fpstate

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impl Hash for _libc_fpxreg

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impl Hash for _libc_xmmreg

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impl Hash for addrinfo

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impl Hash for af_alg_iv

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impl Hash for aiocb

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impl Hash for arpd_request

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impl Hash for arphdr

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impl Hash for arpreq

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impl Hash for arpreq_old

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impl Hash for can_filter

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impl Hash for clone_args

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impl Hash for cmsghdr

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impl Hash for cpu_set_t

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impl Hash for dirent

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impl Hash for dirent64

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impl Hash for dl_phdr_info

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impl Hash for dqblk

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impl Hash for epoll_event

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impl Hash for fanotify_event_metadata

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impl Hash for fanotify_response

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impl Hash for fd_set

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impl Hash for ff_condition_effect

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impl Hash for ff_constant_effect

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impl Hash for ff_effect

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impl Hash for ff_envelope

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impl Hash for ff_periodic_effect

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impl Hash for ff_ramp_effect

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impl Hash for ff_replay

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impl Hash for ff_rumble_effect

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impl Hash for ff_trigger

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impl Hash for file_clone_range

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impl Hash for flock

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impl Hash for flock64

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impl Hash for fsid_t

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impl Hash for genlmsghdr

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impl Hash for glob64_t

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impl Hash for glob_t

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impl Hash for group

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impl Hash for hostent

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impl Hash for hwtstamp_config

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impl Hash for if_nameindex

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impl Hash for ifaddrs

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impl Hash for in6_addr

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impl Hash for in6_ifreq

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impl Hash for in6_pktinfo

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impl Hash for in6_rtmsg

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impl Hash for in_addr

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impl Hash for in_pktinfo

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impl Hash for inotify_event

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impl Hash for input_absinfo

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impl Hash for input_event

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impl Hash for input_id

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impl Hash for input_keymap_entry

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impl Hash for input_mask

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impl Hash for iocb

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impl Hash for iovec

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impl Hash for ip_mreq

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impl Hash for ip_mreq_source

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impl Hash for ip_mreqn

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impl Hash for ipc_perm

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impl Hash for ipv6_mreq

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impl Hash for itimerspec

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impl Hash for itimerval

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impl Hash for j1939_filter

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impl Hash for lconv

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impl Hash for linger

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impl Hash for mallinfo

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impl Hash for mallinfo2

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impl Hash for mcontext_t

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impl Hash for mmsghdr

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impl Hash for mntent

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impl Hash for mq_attr

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impl Hash for msghdr

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impl Hash for msginfo

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impl Hash for msqid_ds

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impl Hash for nl_mmap_hdr

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impl Hash for nl_mmap_req

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impl Hash for nl_pktinfo

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impl Hash for nlattr

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impl Hash for nlmsgerr

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impl Hash for nlmsghdr

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impl Hash for ntptimeval

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impl Hash for open_how

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impl Hash for option

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impl Hash for packet_mreq

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impl Hash for passwd

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impl Hash for pollfd

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impl Hash for posix_spawn_file_actions_t

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impl Hash for posix_spawnattr_t

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impl Hash for protoent

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impl Hash for pthread_attr_t

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impl Hash for pthread_barrier_t

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impl Hash for pthread_barrierattr_t

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impl Hash for pthread_cond_t

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impl Hash for pthread_condattr_t

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impl Hash for pthread_mutex_t

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impl Hash for pthread_mutexattr_t

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impl Hash for pthread_rwlock_t

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impl Hash for pthread_rwlockattr_t

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impl Hash for ptrace_peeksiginfo_args

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impl Hash for ptrace_rseq_configuration

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impl Hash for ptrace_syscall_info

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impl Hash for regex_t

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impl Hash for regmatch_t

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impl Hash for rlimit

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impl Hash for rlimit64

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impl Hash for rtentry

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impl Hash for rusage

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impl Hash for sched_attr

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impl Hash for sched_param

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impl Hash for sctp_authinfo

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impl Hash for sctp_initmsg

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impl Hash for sctp_nxtinfo

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impl Hash for sctp_prinfo

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impl Hash for sctp_rcvinfo

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impl Hash for sctp_sndinfo

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impl Hash for sctp_sndrcvinfo

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impl Hash for seccomp_data

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impl Hash for seccomp_notif

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impl Hash for seccomp_notif_addfd

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impl Hash for seccomp_notif_resp

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impl Hash for seccomp_notif_sizes

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impl Hash for sem_t

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impl Hash for sembuf

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impl Hash for semid_ds

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impl Hash for seminfo

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impl Hash for servent

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impl Hash for shmid_ds

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impl Hash for sigaction

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impl Hash for sigevent

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impl Hash for siginfo_t

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impl Hash for signalfd_siginfo

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impl Hash for sigset_t

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impl Hash for sigval

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impl Hash for sock_extended_err

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impl Hash for sock_filter

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impl Hash for sock_fprog

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impl Hash for sockaddr

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impl Hash for sockaddr_alg

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impl Hash for sockaddr_in

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impl Hash for sockaddr_in6

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impl Hash for sockaddr_ll

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impl Hash for sockaddr_nl

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impl Hash for sockaddr_storage

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impl Hash for sockaddr_un

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impl Hash for sockaddr_vm

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impl Hash for sockaddr_xdp

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impl Hash for spwd

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impl Hash for stack_t

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impl Hash for stat

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impl Hash for stat64

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impl Hash for statfs

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impl Hash for statfs64

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impl Hash for statvfs

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impl Hash for statvfs64

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impl Hash for statx

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impl Hash for statx_timestamp

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impl Hash for sysinfo

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impl Hash for termios

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impl Hash for termios2

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impl Hash for timespec

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impl Hash for timeval

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impl Hash for timex

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impl Hash for tls12_crypto_info_aes_gcm_128

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impl Hash for tls12_crypto_info_aes_gcm_256

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impl Hash for tls12_crypto_info_chacha20_poly1305

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impl Hash for tls_crypto_info

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impl Hash for tm

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impl Hash for tms

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impl Hash for ucontext_t

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impl Hash for ucred

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impl Hash for uinput_abs_setup

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impl Hash for uinput_ff_erase

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impl Hash for uinput_ff_upload

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impl Hash for uinput_setup

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impl Hash for uinput_user_dev

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impl Hash for user

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impl Hash for user_fpregs_struct

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impl Hash for user_regs_struct

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impl Hash for utimbuf

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impl Hash for utmpx

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impl Hash for utsname

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impl Hash for winsize

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impl Hash for xdp_desc

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impl Hash for xdp_mmap_offsets

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impl Hash for xdp_mmap_offsets_v1

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impl Hash for xdp_options

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impl Hash for xdp_ring_offset

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impl Hash for xdp_ring_offset_v1

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impl Hash for xdp_statistics

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impl Hash for xdp_statistics_v1

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impl Hash for xdp_umem_reg

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impl Hash for xdp_umem_reg_v1

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impl<'a> Hash for Component<'a>

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impl<'a> Hash for Prefix<'a>

1.10.0 · source§

impl<'a> Hash for Location<'a>

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impl<'a, M, T, O> Hash for PartialElement<'a, M, T, O>
where M: Mutability, T: 'a + BitStore, O: BitOrder,

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impl<A, O> Hash for BitArray<A, O>
where A: BitViewSized, O: BitOrder,

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impl<B> Hash for Cow<'_, B>
where B: Hash + ToOwned + ?Sized,

1.55.0 · source§

impl<B, C> Hash for ControlFlow<B, C>
where B: Hash, C: Hash,

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impl<Dyn> Hash for DynMetadata<Dyn>
where Dyn: ?Sized,

1.4.0 · source§

impl<F> Hash for F
where F: FnPtr,

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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,

1.26.0 · source§

impl<Idx> Hash for RangeInclusive<Idx>
where Idx: Hash,

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impl<Idx> Hash for RangeTo<Idx>
where Idx: Hash,

1.26.0 · source§

impl<Idx> Hash for RangeToInclusive<Idx>
where Idx: Hash,

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impl<Inner> Hash for Frozen<Inner>
where Inner: Hash + Mutability,

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impl<K, V, A> Hash for BTreeMap<K, V, A>
where K: Hash, V: Hash, A: Allocator + Clone,

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impl<M, T> Hash for Address<M, T>
where M: Mutability, T: ?Sized,

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impl<M, T, O> Hash for BitPtr<M, T, O>
where M: Mutability, T: BitStore, O: BitOrder,

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impl<M, T, O> Hash for BitPtrRange<M, T, O>
where M: Mutability, T: BitStore, O: BitOrder,

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impl<M, T, O> Hash for BitRef<'_, M, T, O>
where M: Mutability, T: BitStore, O: BitOrder,

1.41.0 · source§

impl<Ptr> Hash for Pin<Ptr>
where Ptr: Deref, <Ptr as Deref>::Target: Hash,

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impl<R> Hash for BitEnd<R>
where R: Hash + BitRegister,

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impl<R> Hash for BitIdx<R>
where R: Hash + BitRegister,

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impl<R> Hash for BitIdxError<R>
where R: Hash + BitRegister,

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impl<R> Hash for BitMask<R>
where R: Hash + BitRegister,

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impl<R> Hash for BitPos<R>
where R: Hash + BitRegister,

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impl<R> Hash for BitSel<R>
where R: Hash + BitRegister,

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impl<T> Hash for Option<T>
where T: Hash,

1.17.0 · source§

impl<T> Hash for Bound<T>
where T: Hash,

1.36.0 · source§

impl<T> Hash for Poll<T>
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 + ?Sized,

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impl<T> Hash for &mut T
where T: Hash + ?Sized,

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impl<T> Hash for [T]
where T: Hash,

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impl<T> Hash for (T₁, T₂, …, Tₙ)
where T: Hash + ?Sized,

This trait is implemented for tuples up to twelve items long.

1.19.0 · source§

impl<T> Hash for Reverse<T>
where T: Hash,

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impl<T> Hash for PhantomData<T>
where T: ?Sized,

1.21.0 · source§

impl<T> Hash for Discriminant<T>

1.20.0 · source§

impl<T> Hash for ManuallyDrop<T>
where T: Hash + ?Sized,

1.74.0 · source§

impl<T> Hash for Saturating<T>
where T: Hash,

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impl<T> Hash for Wrapping<T>
where T: Hash,

1.25.0 · source§

impl<T> Hash for NonNull<T>
where T: ?Sized,

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impl<T> Hash for AllowStdIo<T>
where T: Hash,

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impl<T> Hash for BitPtrError<T>
where T: Hash + BitStore,

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impl<T> Hash for BitSpanError<T>
where T: Hash + BitStore,

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impl<T> Hash for MisalignError<T>
where T: Hash,

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impl<T> Hash for Unalign<T>
where T: Unaligned + Hash,

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impl<T, A> Hash for BTreeSet<T, A>
where T: Hash, A: Allocator + Clone,

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impl<T, A> Hash for LinkedList<T, A>
where T: Hash, A: Allocator,

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impl<T, A> Hash for VecDeque<T, A>
where T: Hash, A: Allocator,

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impl<T, A> Hash for Rc<T, A>
where T: Hash + ?Sized, A: Allocator,

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impl<T, A> Hash for gstd::prelude::Box<T, A>
where T: Hash + ?Sized, A: Allocator,

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impl<T, A> Hash for gstd::prelude::Vec<T, A>
where T: Hash, A: Allocator,

The hash of a vector is the same as that of the corresponding slice, as required by the core::borrow::Borrow implementation.

use std::hash::BuildHasher;

let b = std::hash::RandomState::new();
let v: Vec<u8> = vec![0xa8, 0x3c, 0x09];
let s: &[u8] = &[0xa8, 0x3c, 0x09];
assert_eq!(b.hash_one(v), b.hash_one(s));
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impl<T, A> Hash for Arc<T, A>
where T: Hash + ?Sized, A: Allocator,

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impl<T, A> Hash for Box<T, A>
where T: Hash + ?Sized, A: Allocator,

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impl<T, A> Hash for Vec<T, A>
where T: Hash, A: Allocator,

The hash of a vector is the same as that of the corresponding slice, as required by the core::borrow::Borrow implementation.

#![feature(build_hasher_simple_hash_one)]
use std::hash::BuildHasher;

let b = std::collections::hash_map::RandomState::new();
let v: Vec<u8> = vec![0xa8, 0x3c, 0x09];
let s: &[u8] = &[0xa8, 0x3c, 0x09];
assert_eq!(b.hash_one(v), b.hash_one(s));
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impl<T, E> Hash for Result<T, E>
where T: Hash, E: Hash,

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impl<T, O> Hash for BitBox<T, O>
where T: BitStore, O: BitOrder,

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impl<T, O> Hash for BitSlice<T, O>
where T: BitStore, O: BitOrder,

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impl<T, O> Hash for BitVec<T, O>
where T: BitStore, O: BitOrder,

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impl<T, const CAP: usize> Hash for ArrayVec<T, CAP>
where T: Hash,

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impl<T, const N: usize> Hash for [T; N]
where T: Hash,

The hash of an array is the same as that of the corresponding slice, as required by the Borrow implementation.

use std::hash::BuildHasher;

let b = std::hash::RandomState::new();
let a: [u8; 3] = [0xa8, 0x3c, 0x09];
let s: &[u8] = &[0xa8, 0x3c, 0x09];
assert_eq!(b.hash_one(a), b.hash_one(s));
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impl<T, const N: usize> Hash for Simd<T, N>

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impl<Y, R> Hash for CoroutineState<Y, R>
where Y: Hash, R: Hash,

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impl<const CAP: usize> Hash for ArrayString<CAP>