Trait BackingMap 

pub trait BackingMap<K, V>: Sized {
    // Required methods
    fn new() -> Self;
    fn insert(&mut self, key: K, value: V) -> Option<V>;
    fn get(&self, key: &K) -> Option<&V>;
    fn get_mut(&mut self, key: &K) -> Option<&mut V>;
    fn remove(&mut self, key: &K) -> Option<V>;
    fn len(&self) -> usize;
    fn is_empty(&self) -> bool;

    // Provided method
    fn with_capacity(capacity: usize) -> Self { ... }
}

Trait for types that can back a structible struct.

This trait defines the operations required for a map type to be used as the backing storage for a structible struct. It is implemented for HashMap and BTreeMap from the standard library.

Users can implement this trait for custom map types to use them as backing storage.

Required Methods

fn new() -> Self

Creates a new, empty map.

fn insert(&mut self, key: K, value: V) -> Option<V>

Inserts a key-value pair into the map, returning the previous value if present.

fn get(&self, key: &K) -> Option<&V>

Returns a reference to the value for the given key.

fn get_mut(&mut self, key: &K) -> Option<&mut V>

Returns a mutable reference to the value for the given key.

fn remove(&mut self, key: &K) -> Option<V>

Removes a key from the map, returning the value if present.

fn len(&self) -> usize

Returns the number of entries in the map.

fn is_empty(&self) -> bool

Returns true if the map contains no entries.

Provided Methods

fn with_capacity(capacity: usize) -> Self

Creates a new, empty map with capacity for at least capacity elements.

Map types that don’t support pre-allocation (like BTreeMap) can ignore the capacity hint and just call new().

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<K, V> BackingMap<K, V> for BTreeMap<K, V>

where K: Ord,

fn new() -> Self

fn insert(&mut self, key: K, value: V) -> Option<V>

fn get(&self, key: &K) -> Option<&V>

fn get_mut(&mut self, key: &K) -> Option<&mut V>

fn remove(&mut self, key: &K) -> Option<V>

fn len(&self) -> usize

fn is_empty(&self) -> bool

impl<K, V> BackingMap<K, V> for HashMap<K, V>

where K: Eq + Hash,

fn new() -> Self

fn with_capacity(capacity: usize) -> Self

fn insert(&mut self, key: K, value: V) -> Option<V>

fn get(&self, key: &K) -> Option<&V>

fn get_mut(&mut self, key: &K) -> Option<&mut V>

fn remove(&mut self, key: &K) -> Option<V>

fn len(&self) -> usize

fn is_empty(&self) -> bool

Implementors