Struct Map

pub struct Map<K, V> { /* private fields */ }

A default key-value mapping.

Provides an API compatible with both HashMap and BTreeMap.

Implementations

impl<K, V> Map<K, V>

pub fn new() -> Self

Creates a new empty Map.

pub fn clear(&mut self)

Clears the Map, removing all elements.

pub fn len(&self) -> usize

Returns the number of elements in the Map.

pub fn is_empty(&self) -> bool

Returns true if the Map contains no elements.

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

Returns an iterator that yields the items in the Map.

pub fn iter_mut(&mut self) -> IterMut<'_, K, V>

Returns a mutable iterator that yields the items in the Map.

pub fn keys(&self) -> Keys<'_, K, V>

Returns an iterator that yields the keys in the Map.

pub fn into_keys(self) -> IntoKeys<K, V>

Creates a consuming iterator visiting all the keys in arbitrary order.

The Map cannot be used after calling this. The iterator element type is K.

pub fn values(&self) -> Values<'_, K, V>

Returns an iterator that yields the values in the Map.

pub fn into_values(self) -> IntoValues<K, V>

Creates a consuming iterator visiting all the values in arbitrary order.

The Map cannot be used after calling this. The iterator element type is V.

pub fn values_mut(&mut self) -> ValuesMut<'_, K, V>

Returns a mutable iterator that yields the values in the Map.

impl<K, V> Map<K, V>

where K: Hash + Eq + Ord,

pub fn reserve(&mut self, additional: usize)

Reserves capacity for at least additional more elements to be inserted in the Map.

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

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

Returns true if key is contains in the Map.

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

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

Returns a reference to the value corresponding to the key.

pub fn get_key_value<Q>(&self, key: &Q) -> Option<(&K, &V)>

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

Returns the key-value pair corresponding to the supplied key.

The supplied key may be any borrowed form of the map’s key type, but the ordering on the borrowed form must match the ordering on the key type.

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

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

Returns a mutable reference to the value corresponding to the key.

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

Inserts a key-value pair into the Map.

If the map did not have this key present, None is returned.

If the map did have this key present, the value is updated, and the old value is returned. The key is not updated, though; this matters for types that can be == without being identical.

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

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

Removes a key from the Map, returning the value at the key if the key was previously in the map.

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

where K: Borrow<Q>, Q: ?Sized + Hash + Ord,

Removes a key from the Map, returning the stored key and value if the key was previously in the map.

The key may be any borrowed form of the map’s key type, but the ordering on the borrowed form must match the ordering on the key type.

pub fn entry(&mut self, key: K) -> Entry<'_, K, V>

Gets the given key’s corresponding entry in the Map for in-place manipulation.

pub fn retain<F>(&mut self, f: F)

where F: FnMut(&K, &mut V) -> bool,

Retains only the elements specified by the predicate.

In other words, remove all pairs (k, v) for which f(&k, &mut v) returns false. The elements are visited in ascending key order.

Trait Implementations

impl<K: Clone, V: Clone> Clone for Map<K, V>

fn clone(&self) -> Map<K, V>

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<K: Debug, V: Debug> Debug for Map<K, V>

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

Formats the value using the given formatter.

impl<K, V> Default for Map<K, V>

fn default() -> Self

Returns the “default value” for a type.

impl<'a, K, V> Extend<(&'a K, &'a V)> for Map<K, V>

where K: Eq + Hash + Ord + Copy, V: Copy,

fn extend<Iter: IntoIterator<Item = (&'a K, &'a V)>>(&mut self, iter: Iter)

Extends a collection with the contents of an iterator.

fn extend_one(&mut self, item: A)

🔬This is a nightly-only experimental API. (extend_one)

Extends a collection with exactly one element.

fn extend_reserve(&mut self, additional: usize)

🔬This is a nightly-only experimental API. (extend_one)

Reserves capacity in a collection for the given number of additional elements.

impl<K, V> Extend<(K, V)> for Map<K, V>

where K: Eq + Hash + Ord,

fn extend<Iter: IntoIterator<Item = (K, V)>>(&mut self, iter: Iter)

Extends a collection with the contents of an iterator.

fn extend_one(&mut self, item: A)

🔬This is a nightly-only experimental API. (extend_one)

Extends a collection with exactly one element.

fn extend_reserve(&mut self, additional: usize)

🔬This is a nightly-only experimental API. (extend_one)

Reserves capacity in a collection for the given number of additional elements.

impl<K, V> FromIterator<(K, V)> for Map<K, V>

where K: Hash + Eq + Ord,

fn from_iter<I>(iter: I) -> Self

where I: IntoIterator<Item = (K, V)>,

Creates a value from an iterator.

impl<K, Q, V> Index<&Q> for Map<K, V>

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

type Output = V

The returned type after indexing.

fn index(&self, key: &Q) -> &V

Performs the indexing (container[index]) operation.

impl<'a, K, V> IntoIterator for &'a Map<K, V>

type Item = (&'a K, &'a V)

The type of the elements being iterated over.

type IntoIter = Iter<'a, K, V>

Which kind of iterator are we turning this into?

fn into_iter(self) -> Self::IntoIter

Creates an iterator from a value.

impl<'a, K: 'a, V: 'a> IntoIterator for &'a mut Map<K, V>

type Item = (&'a K, &'a mut V)

The type of the elements being iterated over.

type IntoIter = IterMut<'a, K, V>

Which kind of iterator are we turning this into?

fn into_iter(self) -> Self::IntoIter

Creates an iterator from a value.

impl<K, V> IntoIterator for Map<K, V>

type Item = (K, V)

The type of the elements being iterated over.

type IntoIter = IntoIter<K, V>

Which kind of iterator are we turning this into?

fn into_iter(self) -> Self::IntoIter

Creates an iterator from a value.

impl<K, V> PartialEq for Map<K, V>

where K: Eq + Hash, V: Eq,

fn eq(&self, other: &Self) -> 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<K, V> Eq for Map<K, V>

where K: Eq + Hash, V: Eq,