Trait IdHashItem 

pub trait IdHashItem {
    type Key<'a>: Eq + Hash
       where Self: 'a;

    // Required methods
    fn key(&self) -> Self::Key<'_>;
    fn upcast_key<'short, 'long: 'short>(
        long: Self::Key<'long>,
    ) -> Self::Key<'short>;
}

An element stored in an IdHashMap.

This trait is used to define the key type for the map.

Examples

use iddqd::{IdHashItem, IdHashMap, id_upcast};

// Define a struct with a key.
#[derive(Debug, PartialEq, Eq, Hash)]
struct MyItem {
    id: String,
    value: u32,
}

// Implement IdHashItem for the struct.
impl IdHashItem for MyItem {
    // Keys can borrow from the item.
    type Key<'a> = &'a str;

    fn key(&self) -> Self::Key<'_> {
        &self.id
    }

    id_upcast!();
}

// Create an IdHashMap and insert items.
let mut map = IdHashMap::new();
map.insert_unique(MyItem { id: "foo".to_string(), value: 42 }).unwrap();
map.insert_unique(MyItem { id: "bar".to_string(), value: 20 }).unwrap();

Required Associated Types

type Key<'a>: Eq + Hash where Self: 'a

The key type.

Required Methods

fn key(&self) -> Self::Key<'_>

Retrieves the key.

fn upcast_key<'short, 'long: 'short>( long: Self::Key<'long>, ) -> Self::Key<'short>

Upcasts the key to a shorter lifetime, in effect asserting that the lifetime 'a on IdHashItem::Key is covariant.

Typically implemented via the id_upcast macro.

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementations on Foreign Types

impl<'b, T: 'b + ?Sized + IdHashItem> IdHashItem for &'b T

type Key<'a> = <T as IdHashItem>::Key<'a> where Self: 'a

fn key(&self) -> Self::Key<'_>

fn upcast_key<'short, 'long: 'short>( long: Self::Key<'long>, ) -> Self::Key<'short>

where Self: 'long,

impl<'b, T: 'b + ?Sized + IdHashItem> IdHashItem for &'b mut T

type Key<'a> = <T as IdHashItem>::Key<'a> where Self: 'a

fn key(&self) -> Self::Key<'_>

fn upcast_key<'short, 'long: 'short>( long: Self::Key<'long>, ) -> Self::Key<'short>

where Self: 'long,

impl<T: ?Sized + IdHashItem> IdHashItem for Box<T>

type Key<'a> = <T as IdHashItem>::Key<'a> where Self: 'a

fn key(&self) -> Self::Key<'_>

fn upcast_key<'short, 'long: 'short>( long: Self::Key<'long>, ) -> Self::Key<'short>

impl<T: ?Sized + IdHashItem> IdHashItem for Rc<T>

type Key<'a> = <T as IdHashItem>::Key<'a> where Self: 'a

fn key(&self) -> Self::Key<'_>

fn upcast_key<'short, 'long: 'short>( long: Self::Key<'long>, ) -> Self::Key<'short>

impl<T: ?Sized + IdHashItem> IdHashItem for Arc<T>

type Key<'a> = <T as IdHashItem>::Key<'a> where Self: 'a

fn key(&self) -> Self::Key<'_>

fn upcast_key<'short, 'long: 'short>( long: Self::Key<'long>, ) -> Self::Key<'short>

Implementors