core::hash::BuildHasherDefault - Rust
Description: API documentation for the Rust `BuildHasherDefault` struct in crate `core`.
Keywords: rust, rustlang, rust-lang, BuildHasherDefault

# Struct core::hash::BuildHasherDefault 1.7.0 [−] [src]

    pub struct BuildHasherDefault<H>(_);

The `BuildHasherDefault` structure is used in scenarios where one has a type that implements `Hasher` and `Default`, but needs that type to implement `BuildHasher`.

This structure is zero-sized and does not need construction.

# Examples

Using `BuildHasherDefault` to specify a custom `BuildHasher` for [`HashMap`]:

    use std::collections::HashMap;
    use std::hash::{BuildHasherDefault, Hasher};

    #[derive(Default)]
    struct MyHasher;

    impl Hasher for MyHasher {
        fn write(&mut self, bytes: &[u8]) {
            // Your hashing algorithm goes here!
           unimplemented!()
        }

        fn finish(&self) -> u64 {
            // Your hashing algorithm goes here!
            unimplemented!()
        }
    }

    type MyBuildHasher = BuildHasherDefault<MyHasher>;

    let hash_map = HashMap::<u32, u32, MyBuildHasher>::default();Run

## Trait Implementations

### `impl<H> Debug for BuildHasherDefault<H>`
1.9.0
[src]

#### `fn fmt(&self, f: &mut Formatter) -> Result`

Formats the value using the given formatter.

### `impl<H: Default + Hasher> BuildHasher for BuildHasherDefault<H>`
[src]

#### `type Hasher = H`

Type of the hasher that will be created.

#### `fn build_hasher(&self) -> H`

Creates a new hasher. Read more

### `impl<H> Clone for BuildHasherDefault<H>`
[src]

#### `fn clone(&self) -> BuildHasherDefault<H>`

Returns a copy of the value. Read more

#### `fn clone_from(&mut self, source: &Self)`
1.0.0

Performs copy-assignment from `source`. Read more

### `impl<H> Default for BuildHasherDefault<H>`
[src]

#### `fn default() -> BuildHasherDefault<H>`

Returns the "default value" for a type. Read more

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