Struct ordermap::OrderMap

pub struct OrderMap<K, V, S = RandomState> { /* fields omitted */ }

A hash map with consistent order of the key-value pairs.

Order

The key-value pairs have a consistent order that is determined by the sequence of insertion and removal calls on the map. The order does not depend on the keys or the hash function at all.

All iterators traverse the map in the order.

Mutable Keys

Some methods expose &mut K, mutable references to the key as it is stored in the map. The key is allowed to be modified, but only in a way that preserves its hash and equality (it is only useful for composite key structs).

This is sound (memory safe) but a logical error hazard (just like implementing PartialEq, Eq, or Hash incorrectly would be).

Examples

use ordermap::OrderMap;

// count the frequency of each letter in a sentence.
let mut letters = OrderMap::new();
for ch in "a short treatise on fungi".chars() {
    *letters.entry(ch).or_insert(0) += 1;
}
 
assert_eq!(letters[&'s'], 2);
assert_eq!(letters[&'t'], 3);
assert_eq!(letters[&'u'], 1);
assert_eq!(letters.get(&'y'), None);

Methods

impl<K, V> OrderMap<K, V>

pub fn new() -> Self

Create a new map. (Does not allocate.)

pub fn with_capacity(n: usize) -> Self

Create a new map with capacity for n key-value pairs. (Does not allocate if n is zero.)

Computes in O(n) time.

impl<K, V, S> OrderMap<K, V, S>

pub fn with_capacity_and_hasher(n: usize, hash_builder: S) -> Self where     S: BuildHasher,

Create a new map with capacity for n key-value pairs. (Does not allocate if n is zero.)

Computes in O(n) time.

pub fn len(&self) -> usize

Return the number of key-value pairs in the map.

Computes in O(1) time.

pub fn is_empty(&self) -> bool

Returns true if the map contains no elements.

Computes in O(1) time.

pub fn with_hasher(hash_builder: S) -> Self where     S: BuildHasher,

Create a new map with hash_builder

pub fn hasher(&self) -> &S where     S: BuildHasher,

Return a reference to the map's BuildHasher.

pub fn capacity(&self) -> usize

Computes in O(1) time.

impl<K, V, S> OrderMap<K, V, S> where     K: Hash + Eq,     S: BuildHasher,

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

Get the given key’s corresponding entry in the map for in-place manipulation.

Computes in O(1) time (amortized average).

pub fn clear(&mut self)

Remove all key-value pairs in the map, while preserving its capacity.

Computes in O(n) time.

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

FIXME Not implemented fully yet

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

Insert they key-value pair into the map.

If a value already existed for key, that old value is returned in Some; otherwise, return None.

Computes in O(1) time (amortized average).

Important traits for Iter<'a, K, V>

impl<'a, K, V> Iterator for Iter<'a, K, V> type Item = (&'a K, &'a V);

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

Return an iterator over the key-value pairs of the map, in their order

Important traits for IterMut<'a, K, V>

impl<'a, K, V> Iterator for IterMut<'a, K, V> type Item = (&'a K, &'a mut V);

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

Return an iterator over the key-value pairs of the map, in their order

Important traits for Keys<'a, K, V>

impl<'a, K, V> Iterator for Keys<'a, K, V> type Item = &'a K;

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

Return an iterator over the keys of the map, in their order

Important traits for Values<'a, K, V>

impl<'a, K, V> Iterator for Values<'a, K, V> type Item = &'a V;

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

Return an iterator over the values of the map, in their order

Important traits for ValuesMut<'a, K, V>

impl<'a, K, V> Iterator for ValuesMut<'a, K, V> type Item = &'a mut V;

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

Return an iterator over mutable references to the the values of the map, in their order

pub fn contains_key<Q: ?Sized>(&self, key: &Q) -> bool where     K: Borrow<Q>,     Q: Eq + Hash,

Return true if and equivalent to key exists in the map.

Computes in O(1) time (average).

pub fn get<Q: ?Sized>(&self, key: &Q) -> Option<&V> where     K: Borrow<Q>,     Q: Eq + Hash,

Return a reference to the value stored for key, if it is present, else None.

Computes in O(1) time (average).

pub fn get_pair<Q: ?Sized>(&self, key: &Q) -> Option<(&K, &V)> where     K: Borrow<Q>,     Q: Eq + Hash,

pub fn get_pair_index<Q: ?Sized>(&self, key: &Q) -> Option<(usize, &K, &V)> where     K: Borrow<Q>,     Q: Eq + Hash,

Return item index, key and value

pub fn get_mut<Q: ?Sized>(&mut self, key: &Q) -> Option<&mut V> where     K: Borrow<Q>,     Q: Eq + Hash,

pub fn get_pair_mut<Q: ?Sized>(&mut self, key: &Q) -> Option<(&mut K, &mut V)> where     K: Borrow<Q>,     Q: Eq + Hash,

pub fn get_pair_index_mut<Q: ?Sized>(     &mut self,     key: &Q ) -> Option<(usize, &mut K, &mut V)> where     K: Borrow<Q>,     Q: Eq + Hash,

pub fn swap_remove<Q: ?Sized>(&mut self, key: &Q) -> Option<V> where     K: Borrow<Q>,     Q: Eq + Hash,

Remove the key-value pair equivalent to key and return its value.

Like Vec::swap_remove, the pair is removed by swapping it with the last element of the map and popping it off. This perturbs the postion of what used to be the last element!

Return None if key is not in map.

Computes in O(1) time (average).

pub fn remove<Q: ?Sized>(&mut self, key: &Q) -> Option<V> where     K: Borrow<Q>,     Q: Eq + Hash,

FIXME Same as .swap_remove

Computes in O(1) time (average).

pub fn swap_remove_pair<Q: ?Sized>(&mut self, key: &Q) -> Option<(K, V)> where     K: Borrow<Q>,     Q: Eq + Hash,

Remove the key-value pair equivalent to key and return it.

Like Vec::swap_remove, the pair is removed by swapping it with the last element of the map and popping it off. This perturbs the postion of what used to be the last element!

Return None if key is not in map.

pub fn pop(&mut self) -> Option<(K, V)>

Remove the last key-value pair

Computes in O(1) time (average).

pub fn retain<F>(&mut self, keep: F) where     F: FnMut(&mut K, &mut V) -> bool,

Scan through each key-value pair in the map and keep those where the closure keep returns true.

The order the elements are visited is not specified.

Computes in O(n) time (average).

Important traits for IntoIter<K, V>

impl<K, V> Iterator for IntoIter<K, V> type Item = (K, V);

pub fn sorted_by<F>(self, cmp: F) -> IntoIter<K, V> where     F: FnMut(&K, &V, &K, &V) -> Ordering,

Sort the key-value pairs of the map and return a by value iterator of the key-value pairs with the result.

The sort is stable.

Important traits for Drain<'a, K, V>

impl<'a, K, V> Iterator for Drain<'a, K, V> type Item = (K, V);

pub fn drain(&mut self, range: RangeFull) -> Drain<K, V>

Clears the OrderMap, returning all key-value pairs as a drain iterator. Keeps the allocated memory for reuse.

impl<K, V, S> OrderMap<K, V, S>

pub fn get_index(&self, index: usize) -> Option<(&K, &V)>

Get a key-value pair by index

Valid indices are 0 <= index < self.len()

Computes in O(1) time.

pub fn get_index_mut(&mut self, index: usize) -> Option<(&mut K, &mut V)>

Get a key-value pair by index

Valid indices are 0 <= index < self.len()

Computes in O(1) time.

pub fn swap_remove_index(&mut self, index: usize) -> Option<(K, V)>

Remove the key-value pair by index

Valid indices are 0 <= index < self.len()

Computes in O(1) time (average).

Trait Implementations

impl<K: Clone, V: Clone, S: Clone> Clone for OrderMap<K, V, S>

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

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<K, V, S> Debug for OrderMap<K, V, S> where     K: Debug + Hash + Eq,     V: Debug,     S: BuildHasher,

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

Formats the value using the given formatter.

impl<'a, K, V, S> IntoIterator for &'a OrderMap<K, V, S> where     K: Hash + Eq,     S: BuildHasher,

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, V, S> IntoIterator for &'a mut OrderMap<K, V, S> where     K: Hash + Eq,     S: BuildHasher,

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, S> IntoIterator for OrderMap<K, V, S> where     K: Hash + Eq,     S: BuildHasher,

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<'a, K, V, Q: ?Sized, S> Index<&'a Q> for OrderMap<K, V, S> where     K: Eq + Hash,     K: Borrow<Q>,     Q: Eq + Hash,     S: BuildHasher,

type Output = V

The returned type after indexing.

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

Panics if key is not present in the map.

impl<'a, K, V, Q: ?Sized, S> IndexMut<&'a Q> for OrderMap<K, V, S> where     K: Eq + Hash,     K: Borrow<Q>,     Q: Eq + Hash,     S: BuildHasher,

Mutable indexing allows changing / updating values of key-value pairs that are already present.

You can not insert new pairs with index syntax, use .insert().

fn index_mut(&mut self, key: &'a Q) -> &mut V

Panics if key is not present in the map.

impl<K, V, S> FromIterator<(K, V)> for OrderMap<K, V, S> where     K: Hash + Eq,     S: BuildHasher + Default,

fn from_iter<I: IntoIterator<Item = (K, V)>>(iterable: I) -> Self

Creates a value from an iterator.

impl<K, V, S> Extend<(K, V)> for OrderMap<K, V, S> where     K: Hash + Eq,     S: BuildHasher,

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

Extends a collection with the contents of an iterator.

impl<K, V, S> Default for OrderMap<K, V, S> where     S: BuildHasher + Default,

fn default() -> Self

Returns the "default value" for a type.

impl<K, V1, S1, V2, S2> PartialEq<OrderMap<K, V2, S2>> for OrderMap<K, V1, S1> where     K: Hash + Eq,     V1: PartialEq<V2>,     S1: BuildHasher,     S2: BuildHasher,

fn eq(&self, other: &OrderMap<K, V2, S2>) -> bool

This method tests for self and other values to be equal, and is used by ==.

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

This method tests for !=.

impl<K, V, S> Eq for OrderMap<K, V, S> where     K: Eq + Hash,     V: Eq,     S: BuildHasher,