Struct ordermap::OrderMap
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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>
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fn new() -> Self
Create a new map. (Does not allocate.)
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>
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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.
fn len(&self) -> usize
Return the number of key-value pairs in the map.
Computes in O(1) time.
fn capacity(&self) -> usize
Computes in O(1) time.
impl<K, V, S> OrderMap<K, V, S> where K: Hash + Eq, S: BuildHasher
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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).
fn clear(&mut self)
Remove all key-value pairs in the map, while preserving its capacity.
Computes in O(n) time.
fn reserve(&mut self, additional: usize)
FIXME Not implemented fully yet
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).
fn iter(&self) -> Iter<K, V>
Return an iterator over the key-value pairs of the map, in their order
fn iter_mut(&mut self) -> IterMut<K, V>
Return an iterator over the key-value pairs of the map, in their order
fn keys(&self) -> Keys<K, V>
Return an iterator over the keys of the map, in their order
fn values(&self) -> Values<K, V>
Return an iterator over the values of the map, in their order
fn values_mut(&mut self) -> ValuesMut<K, V>
Return an iterator over mutable references to the the values of the map, in their order
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).
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).
fn get_pair<Q: ?Sized>(&self, key: &Q) -> Option<(&K, &V)> where K: Borrow<Q>, Q: Eq + Hash
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
fn get_mut<Q: ?Sized>(&mut self, key: &Q) -> Option<&mut V> where K: Borrow<Q>, Q: Eq + Hash
fn get_pair_mut<Q: ?Sized>(&mut self, key: &Q) -> Option<(&mut K, &mut V)> where K: Borrow<Q>, Q: Eq + Hash
fn get_pair_index_mut<Q: ?Sized>(&mut self,
key: &Q)
-> Option<(usize, &mut K, &mut V)> where K: Borrow<Q>, Q: Eq + Hash
key: &Q)
-> Option<(usize, &mut K, &mut V)> where K: Borrow<Q>, Q: Eq + Hash
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).
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).
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.
fn pop(&mut self) -> Option<(K, V)>
Remove the last key-value pair
Computes in O(1) time (average).
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).
impl<K, V, S> OrderMap<K, V, S>
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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.
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.
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>
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fn clone(&self) -> OrderMap<K, V, S>
Returns a copy of the value. Read more
fn clone_from(&mut self, source: &Self)
1.0.0
Performs copy-assignment from source
. Read more
impl<K, V, S> Debug for OrderMap<K, V, S> where K: Debug + Hash + Eq,
V: Debug,
S: BuildHasher
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V: Debug,
S: BuildHasher
impl<'a, K, V, S> IntoIterator for &'a OrderMap<K, V, S> where K: Hash + Eq,
S: BuildHasher
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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. Read more
impl<'a, K, V, S> IntoIterator for &'a mut OrderMap<K, V, S> where K: Hash + Eq,
S: BuildHasher
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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. Read more
impl<K, V, S> IntoIterator for OrderMap<K, V, S> where K: Hash + Eq,
S: BuildHasher
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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. Read more
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
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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
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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
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S: BuildHasher + Default
fn from_iter<I: IntoIterator<Item=(K, V)>>(iterable: I) -> Self
Creates a value from an iterator. Read more
impl<K, V, S> Extend<(K, V)> for OrderMap<K, V, S> where K: Hash + Eq,
S: BuildHasher
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S: BuildHasher
fn extend<I: IntoIterator<Item=(K, V)>>(&mut self, iterable: I)
Extends a collection with the contents of an iterator. Read more