Struct MultiMap

pub struct MultiMap<K1, K2, V>
where
    K1: Eq + Hash,
    K2: Eq + Hash,
{ /* private fields */ }

Implementations

impl<K1, K2, V> MultiMap<K1, K2, V>

where K1: Eq + Hash + Clone, K2: Eq + Hash + Clone,

pub fn new() -> MultiMap<K1, K2, V>

Creates a new MultiMap. The primary key is of type K1 and the secondary key is of type K2. The value is of type V. This is as compared to a std::collections::HashMap which is typed on just K and V.

Internally, two HashMaps are created - a main one on <K1, (K2, V)> and a second one on <K2, K1>. The (K2, V) tuple is so that when an item is removed using the K1 key, the appropriate K2 value is available so the K2->K1 map can be removed from the second HashMap, to keep them in sync.

pub fn with_capacity(capacity: usize) -> MultiMap<K1, K2, V>

Creates an empty MultiMap with the specified capacity.

The multi map will be able to hold at least capacity elements without reallocating. If capacity is 0, the multi map will not allocate.

pub fn insert(&mut self, key_one: K1, key_two: K2, value: V)

Insert an item into the MultiMap. You must supply both keys to insert an item. The keys cannot be modified at a later date, so if you only have one key at this time, use a placeholder value for the second key (perhaps K2 is Option<...>) and remove then re-insert when the second key becomes available.

pub fn get(&self, key: &K1) -> Option<&V>

Obtain a reference to an item in the MultiMap using the primary key, just like a HashMap.

pub fn get_mut(&mut self, key: &K1) -> Option<&mut V>

Obtain a mutable reference to an item in the MultiMap using the primary key, just like a HashMap.

pub fn get_alt(&self, key: &K2) -> Option<&V>

Obtain a reference to an item in the MultiMap using the secondary key. Ordinary HashMaps can’t do this.

pub fn get_mut_alt(&mut self, key: &K2) -> Option<&mut V>

Obtain a mutable reference to an item in the MultiMap using the secondary key. Ordinary HashMaps can’t do this.

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

where K1: Borrow<Q>, Q: Hash + Eq + ?Sized,

Remove an item from the HashMap using the primary key. The value for the given key is returned (if it exists), just like a HashMap. This removes an item from the main HashMap, and the second <K2, K1> HashMap.

pub fn contains_key<Q>(&self, key: &Q) -> bool

where K1: Borrow<Q>, Q: Hash + Eq + ?Sized,

Returns true if the map contains a value for the specified key. The key may be any borrowed form of the map’s key type, but Hash and Eq on the borrowed form must match those for the key type

Example

#[macro_use]
extern crate multi_map;
use multi_map::MultiMap;
let map = multimap! {
    1, "One" => String::from("Eins"),
    2, "Two" => String::from("Zwei"),
    3, "Three" => String::from("Drei"),
};
assert!(map.contains_key(&1));
assert!(!map.contains_key(&4));

pub fn contains_key_alt<Q>(&self, key: &Q) -> bool

where K2: Borrow<Q>, Q: Hash + Eq + ?Sized,

Returns true if the map contains a value for the specified alternative key. The key may be any borrowed form of the map’s key type, but Hash and Eq on the borrowed form must match those for the key type

Example

#[macro_use]
extern crate multi_map;
use multi_map::MultiMap;
let map = multimap! {
    1, "One" => String::from("Eins"),
    2, "Two" => String::from("Zwei"),
    3, "Three" => String::from("Drei"),
};
assert!(map.contains_key_alt(&"One"));
assert!(!map.contains_key_alt(&"Four"));

pub fn remove_alt<Q>(&mut self, key: &Q) -> Option<V>

where K2: Borrow<Q>, Q: Hash + Eq + ?Sized,

Remove an item from the HashMap using the secondary key. The value for the given key is returned (if it exists). Ordinary HashMaps can’t do this. This removes an item from both the main HashMap and the second <K2, K1> HashMap.

pub fn iter(&self) -> Iter<'_, K1, (K2, V)>

Iterate through all the values in the MultiMap. Note that the values are (K2, V) tuples, not V, as you would get with a HashMap.

Trait Implementations

impl<K1, K2, V> Debug for MultiMap<K1, K2, V>

where K1: Eq + Hash + Debug, K2: Eq + Hash + Debug, V: Debug,

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl<K1, K2, V> PartialEq for MultiMap<K1, K2, V>

where K1: Eq + Hash, K2: Eq + Hash, V: Eq,

fn eq(&self, other: &MultiMap<K1, K2, V>) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<K1, K2, V> Eq for MultiMap<K1, K2, V>

where K1: Eq + Hash, K2: Eq + Hash, V: Eq,