Struct LinearMap

pub struct LinearMap<K, V>(/* private fields */);

A linear key-value map backed by a Vec.

This map performs O(n) lookups and inserts. It is suitable only for small sets of keys which must implement Eq.

Internally stores key-value pairs in insertion order. Duplicate key inserts overwrite the previous value.

Performance

Avoid using this for more than a few keys. All core operations are linear.

Implementations

impl<K: Eq, V> LinearMap<K, V>

pub fn new() -> Self

Creates a new empty LinearMap.

pub fn with_capacity(capacity: usize) -> Self

Creates a new empty LinearMap with a pre-allocated capacity.

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

Gets a reference to the value associated with the key, if it exists.

Returns Some(&V) if found, or None if not present.

This is an O(n) operation.

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

Gets a mutable reference to the value associated with the key, if it exists.

Returns Some(&mut V) if found, or None otherwise.

This is an O(n) operation.

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

Inserts a key-value pair into the map.

If the key exists, swaps the old value with the new one and returns the old value. Otherwise, appends the new pair and returns None.

This is an O(n) operation due to the linear search.

pub fn get_or_insert_with(&mut self, k: K, f: impl FnOnce() -> V) -> &mut V

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

If the key exists, returns a mutable reference to the value. Otherwise, inserts a new value created by the provided closure and returns a reference to it.

This is an O(n) operation due to the key search.

pub fn values(&self) -> impl Iterator<Item = &V>

Returns an iterator over the values in the map.

Values are yielded in insertion order.

pub fn keys(&self) -> impl Iterator<Item = &K>

Returns an iterator over the keys in the map.

Keys are yielded in insertion order.

pub fn iter(&self) -> impl Iterator<Item = &(K, V)>

Returns an iterator over all key-value pairs in the map.

Items are yielded in insertion order.

Trait Implementations

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

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

Formats the value using the given formatter.

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

fn default() -> Self

Returns the “default value” for a type.

impl<K: Eq, V> FromIterator<(K, V)> for LinearMap<K, V>

fn from_iter<T: IntoIterator<Item = (K, V)>>(iter: T) -> Self

Builds a LinearMap from an iterator of key-value pairs.

Later duplicates overwrite earlier entries.

This calls insert in a loop, so is O(n^2)!!

impl<K: Eq, V> Index<&K> for LinearMap<K, V>

type Output = V

The returned type after indexing.

fn index(&self, index: &K) -> &Self::Output

Performs the indexing (container[index]) operation.

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

type Item = &'a (K, V)

The type of the elements being iterated over.

type IntoIter = <&'a Vec<(K, V)> as IntoIterator>::IntoIter

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 LinearMap<K, V>

type Item = (K, V)

The type of the elements being iterated over.

type IntoIter = <Vec<(K, V)> as IntoIterator>::IntoIter

Which kind of iterator are we turning this into?

fn into_iter(self) -> Self::IntoIter

Creates an iterator from a value.