[−][src]Struct slotmap::sparse_secondary::SparseSecondaryMap
Sparse secondary map, associate data with previously stored elements in a slot map.
A SparseSecondaryMap
allows you to efficiently store additional
information for each element in a slot map. You can have multiple secondary
maps per slot map, but not multiple slot maps per secondary map. It is safe
but unspecified behavior if you use keys from multiple different slot maps
in the same SparseSecondaryMap
.
A SparseSecondaryMap
does not leak memory even if you never remove
elements. In return, when you remove a key from the primary slot map, after
any insert the space associated with the removed element may be reclaimed.
Don't expect the values associated with a removed key to stick around after
an insertion has happened!
Unlike a SlotMap
, a SparseSecondaryMap
s elements do not need to be
Slottable
. This means that if you can't or don't want to use nightly
Rust, and your data is not Slottable
, you can store that data as
secondary data.
Unlike SecondaryMap
, the SparseSecondaryMap
is backed by a
HashMap
. This means its access times are higher, but it uses less memory
and iterates faster if there are only a few elements of the slot map in the
secondary map. If most or all of the elements in a slot map are also found
in the secondary map, use a SecondaryMap
instead.
Example usage:
// Nightly Rust needed to store String which is not Copy. let mut players: SlotMap<_, &'static str> = SlotMap::new(); // But not for secondary maps. let mut nicks: SparseSecondaryMap<_, String> = SparseSecondaryMap::new(); let mut health = SparseSecondaryMap::new(); let mut ammo = SparseSecondaryMap::new(); let alice = players.insert("alice"); nicks.insert(alice, "the_dragon1".to_string()); let bob = players.insert("bob"); nicks.insert(bob, "bobby_".to_string()); for p in players.keys() { health.insert(p, 100); ammo.insert(p, 30); } // Alice attacks Bob with all her ammo! health[bob] -= ammo[alice] * 3; ammo[alice] = 0;
Methods
impl<K: Key, V> SparseSecondaryMap<K, V, RandomState>
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pub fn new() -> Self
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Constructs a new, empty SparseSecondaryMap
.
Examples
let mut sec: SparseSecondaryMap<DefaultKey, i32> = SparseSecondaryMap::new();
pub fn with_capacity(capacity: usize) -> Self
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Creates an empty SparseSecondaryMap
with the given capacity of slots.
The secondary map will not reallocate until it holds at least capacity
slots.
Examples
let mut sm: SlotMap<_, i32> = SlotMap::with_capacity(10); let mut sec: SparseSecondaryMap<DefaultKey, i32> = SparseSecondaryMap::with_capacity(sm.capacity());
impl<K: Key, V, S: BuildHasher> SparseSecondaryMap<K, V, S>
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pub fn with_hasher(hash_builder: S) -> Self
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Creates an empty SparseSecondaryMap
which will use the given hash
builder to hash keys.
The secondary map will not reallocate until it holds at least capacity
slots.
Examples
let mut sm: SlotMap<_, i32> = SlotMap::with_capacity(10); let mut sec: SparseSecondaryMap<DefaultKey, i32, _> = SparseSecondaryMap::with_hasher(RandomState::new());
pub fn with_capacity_and_hasher(capacity: usize, hash_builder: S) -> Self
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Creates an empty SparseSecondaryMap
with the given capacity of slots,
using hash_builder
to hash the keys.
The secondary map will not reallocate until it holds at least capacity
slots.
Examples
let mut sm: SlotMap<_, i32> = SlotMap::with_capacity(10); let mut sec: SparseSecondaryMap<DefaultKey, i32, _> = SparseSecondaryMap::with_capacity_and_hasher(10, RandomState::new());
pub fn len(&self) -> usize
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Returns the number of elements in the secondary map.
Examples
let mut sm = SlotMap::new(); let k = sm.insert(4); let mut squared = SparseSecondaryMap::new(); assert_eq!(squared.len(), 0); squared.insert(k, 16); assert_eq!(squared.len(), 1);
pub fn is_empty(&self) -> bool
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Returns if the secondary map is empty.
Examples
let mut sec: SparseSecondaryMap<DefaultKey, i32> = SparseSecondaryMap::new(); assert!(sec.is_empty());
pub fn capacity(&self) -> usize
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Returns the number of elements the SparseSecondaryMap
can hold without
reallocating.
Examples
let mut sec: SparseSecondaryMap<DefaultKey, i32> = SparseSecondaryMap::with_capacity(10); assert!(sec.capacity() >= 10);
pub fn reserve(&mut self, additional: usize)
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Reserves capacity for at least additional
more slots in the
SparseSecondaryMap
. The collection may reserve more space to avoid
frequent reallocations.
Panics
Panics if the new allocation size overflows usize
.
Examples
let mut sec: SparseSecondaryMap<DefaultKey, i32> = SparseSecondaryMap::new(); sec.reserve(10); assert!(sec.capacity() >= 10);
pub fn contains_key(&self, key: K) -> bool
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Returns true
if the secondary map contains key
.
Examples
let mut sm = SlotMap::new(); let k = sm.insert(4); let mut squared = SparseSecondaryMap::new(); assert!(!squared.contains_key(k)); squared.insert(k, 16); assert!(squared.contains_key(k));
pub fn insert(&mut self, key: K, value: V) -> Option<V>
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Inserts a value into the secondary map at the given key
. Can silently
fail if key
was removed from the originating slot map.
Returns None
if this key was not present in the map, the old value
otherwise.
Examples
let mut sm = SlotMap::new(); let k = sm.insert(4); let mut squared = SparseSecondaryMap::new(); assert_eq!(squared.insert(k, 0), None); assert_eq!(squared.insert(k, 4), Some(0)); // You don't have to use insert if the key is already in the secondary map. squared[k] *= squared[k]; assert_eq!(squared[k], 16);
pub fn remove(&mut self, key: K) -> Option<V>
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Removes a key from the secondary map, returning the value at the key if
the key was not previously removed. If key
was removed from the
originating slot map, its corresponding entry in the secondary map may
or may not already be removed.
Examples
let mut sm = SlotMap::new(); let mut squared = SparseSecondaryMap::new(); let k = sm.insert(4); squared.insert(k, 16); squared.remove(k); assert!(!squared.contains_key(k)); // It's not necessary to remove keys deleted from the primary slot map, they // get deleted automatically when their slots are reused on a subsequent insert. squared.insert(k, 16); sm.remove(k); // Remove k from the slot map, making an empty slot. let new_k = sm.insert(2); // Since sm only has one empty slot, this reuses it. assert!(!squared.contains_key(new_k)); // Space reuse does not mean equal keys. assert!(squared.contains_key(k)); // Slot has not been reused in squared yet. squared.insert(new_k, 4); assert!(!squared.contains_key(k)); // Old key is no longer available.
pub fn retain<F>(&mut self, f: F) where
F: FnMut(K, &mut V) -> bool,
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F: FnMut(K, &mut V) -> bool,
Retains only the elements specified by the predicate.
In other words, remove all key-value pairs (k, v)
such that
f(k, &mut v)
returns false. This method invalidates any removed keys.
Examples
let mut sm = SlotMap::new(); let mut sec = SparseSecondaryMap::new(); let k1 = sm.insert(0); sec.insert(k1, 10); let k2 = sm.insert(1); sec.insert(k2, 11); let k3 = sm.insert(2); sec.insert(k3, 12); sec.retain(|key, val| key == k1 || *val == 11); assert!(sec.contains_key(k1)); assert!(sec.contains_key(k2)); assert!(!sec.contains_key(k3)); assert_eq!(2, sec.len());
pub fn clear(&mut self)
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Clears the secondary map. Keeps the allocated memory for reuse.
Examples
let mut sm = SlotMap::new(); let mut sec = SparseSecondaryMap::new(); for i in 0..10 { sec.insert(sm.insert(i), i); } assert_eq!(sec.len(), 10); sec.clear(); assert_eq!(sec.len(), 0);
ⓘImportant traits for Drain<'a, K, V>pub fn drain(&mut self) -> Drain<K, V>
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Clears the slot map, returning all key-value pairs in arbitrary order as an iterator. Keeps the allocated memory for reuse.
Examples
let mut sm = SlotMap::new(); let k = sm.insert(0); let mut sec = SparseSecondaryMap::new(); sec.insert(k, 1); let v: Vec<_> = sec.drain().collect(); assert_eq!(sec.len(), 0); assert_eq!(v, vec![(k, 1)]);
pub fn get(&self, key: K) -> Option<&V>
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Returns a reference to the value corresponding to the key.
Examples
let mut sm = SlotMap::new(); let key = sm.insert("foo"); let mut sec = SparseSecondaryMap::new(); sec.insert(key, "bar"); assert_eq!(sec.get(key), Some(&"bar")); sec.remove(key); assert_eq!(sec.get(key), None);
pub fn get_mut(&mut self, key: K) -> Option<&mut V>
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Returns a mutable reference to the value corresponding to the key.
Examples
let mut sm = SlotMap::new(); let key = sm.insert("test"); let mut sec = SparseSecondaryMap::new(); sec.insert(key, 3.5); if let Some(x) = sec.get_mut(key) { *x += 3.0; } assert_eq!(sec[key], 6.5);
ⓘImportant traits for Iter<'a, K, V>pub fn iter(&self) -> Iter<K, V>
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An iterator visiting all key-value pairs in arbitrary order. The
iterator element type is (K, &'a V)
.
This function must iterate over all slots, empty or not. In the face of many deleted elements it can be inefficient.
Examples
let mut sm = SlotMap::new(); let mut sec = SparseSecondaryMap::new(); let k0 = sm.insert(0); sec.insert(k0, 10); let k1 = sm.insert(1); sec.insert(k1, 11); let k2 = sm.insert(2); sec.insert(k2, 12); for (k, v) in sec.iter() { println!("key: {:?}, val: {}", k, v); }
ⓘImportant traits for IterMut<'a, K, V>pub fn iter_mut(&mut self) -> IterMut<K, V>
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An iterator visiting all key-value pairs in arbitrary order, with
mutable references to the values. The iterator element type is
(K, &'a mut V)
.
This function must iterate over all slots, empty or not. In the face of many deleted elements it can be inefficient.
Examples
let mut sm = SlotMap::new(); let mut sec = SparseSecondaryMap::new(); let k0 = sm.insert(1); sec.insert(k0, 10); let k1 = sm.insert(2); sec.insert(k1, 20); let k2 = sm.insert(3); sec.insert(k2, 30); for (k, v) in sec.iter_mut() { if k != k1 { *v *= -1; } } assert_eq!(sec[k0], -10); assert_eq!(sec[k1], 20); assert_eq!(sec[k2], -30);
ⓘImportant traits for Keys<'a, K, V>pub fn keys(&self) -> Keys<K, V>
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An iterator visiting all keys in arbitrary order. The iterator element
type is K
.
This function must iterate over all slots, empty or not. In the face of many deleted elements it can be inefficient.
Examples
let mut sm = SlotMap::new(); let mut sec = SparseSecondaryMap::new(); let k0 = sm.insert(1); sec.insert(k0, 10); let k1 = sm.insert(2); sec.insert(k1, 20); let k2 = sm.insert(3); sec.insert(k2, 30); let keys: HashSet<_> = sec.keys().collect(); let check: HashSet<_> = vec![k0, k1, k2].into_iter().collect(); assert_eq!(keys, check);
ⓘImportant traits for Values<'a, K, V>pub fn values(&self) -> Values<K, V>
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An iterator visiting all values in arbitrary order. The iterator element
type is &'a V
.
This function must iterate over all slots, empty or not. In the face of many deleted elements it can be inefficient.
Examples
let mut sm = SlotMap::new(); let mut sec = SparseSecondaryMap::new(); let k0 = sm.insert(1); sec.insert(k0, 10); let k1 = sm.insert(2); sec.insert(k1, 20); let k2 = sm.insert(3); sec.insert(k2, 30); let values: HashSet<_> = sec.values().collect(); let check: HashSet<_> = vec![&10, &20, &30].into_iter().collect(); assert_eq!(values, check);
ⓘImportant traits for ValuesMut<'a, K, V>pub fn values_mut(&mut self) -> ValuesMut<K, V>
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An iterator visiting all values mutably in arbitrary order. The iterator
element type is &'a mut V
.
This function must iterate over all slots, empty or not. In the face of many deleted elements it can be inefficient.
Examples
let mut sm = SlotMap::new(); let mut sec = SparseSecondaryMap::new(); sec.insert(sm.insert(1), 10); sec.insert(sm.insert(2), 20); sec.insert(sm.insert(3), 30); sec.values_mut().for_each(|n| { *n *= 3 }); let values: HashSet<_> = sec.into_iter().map(|(_k, v)| v).collect(); let check: HashSet<_> = vec![30, 60, 90].into_iter().collect(); assert_eq!(values, check);
Trait Implementations
impl<K, V, S> PartialEq<SparseSecondaryMap<K, V, S>> for SparseSecondaryMap<K, V, S> where
K: Key,
V: PartialEq,
S: BuildHasher,
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K: Key,
V: PartialEq,
S: BuildHasher,
fn eq(&self, other: &Self) -> bool
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#[must_use]
fn ne(&self, other: &Rhs) -> bool
1.0.0[src]
This method tests for !=
.
impl<K, V, S> Default for SparseSecondaryMap<K, V, S> where
K: Key,
S: BuildHasher + Default,
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K: Key,
S: BuildHasher + Default,
impl<'a, K, V, S> IntoIterator for &'a SparseSecondaryMap<K, V, S> where
K: Key,
S: BuildHasher,
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K: Key,
S: BuildHasher,
type Item = (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
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impl<'a, K, V, S> IntoIterator for &'a mut SparseSecondaryMap<K, V, S> where
K: Key,
S: BuildHasher,
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K: Key,
S: BuildHasher,
type Item = (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
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impl<K, V, S> IntoIterator for SparseSecondaryMap<K, V, S> where
K: Key,
S: BuildHasher,
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K: Key,
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
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impl<K, V, S> Extend<(K, V)> for SparseSecondaryMap<K, V, S> where
K: Key,
S: BuildHasher,
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K: Key,
S: BuildHasher,
fn extend<I: IntoIterator<Item = (K, V)>>(&mut self, iter: I)
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impl<'a, K, V, S> Extend<(K, &'a V)> for SparseSecondaryMap<K, V, S> where
K: Key,
V: 'a + Copy,
S: BuildHasher,
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K: Key,
V: 'a + Copy,
S: BuildHasher,
impl<K: Clone + Key, V: Clone, S: Clone + BuildHasher> Clone for SparseSecondaryMap<K, V, S>
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fn clone(&self) -> SparseSecondaryMap<K, V, S>
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fn clone_from(&mut self, source: &Self)
1.0.0[src]
Performs copy-assignment from source
. Read more
impl<K, V, S> Eq for SparseSecondaryMap<K, V, S> where
K: Key,
V: Eq,
S: BuildHasher,
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K: Key,
V: Eq,
S: BuildHasher,
impl<K: Debug + Key, V: Debug, S: Debug + BuildHasher> Debug for SparseSecondaryMap<K, V, S>
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impl<K, V, S> Index<K> for SparseSecondaryMap<K, V, S> where
K: Key,
S: BuildHasher,
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K: Key,
S: BuildHasher,
impl<K, V, S> IndexMut<K> for SparseSecondaryMap<K, V, S> where
K: Key,
S: BuildHasher,
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K: Key,
S: BuildHasher,
impl<K, V, S> FromIterator<(K, V)> for SparseSecondaryMap<K, V, S> where
K: Key,
S: BuildHasher + Default,
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K: Key,
S: BuildHasher + Default,
fn from_iter<I: IntoIterator<Item = (K, V)>>(iter: I) -> Self
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Auto Trait Implementations
impl<K, V, S> Send for SparseSecondaryMap<K, V, S> where
S: Send,
V: Send,
S: Send,
V: Send,
impl<K, V, S> Unpin for SparseSecondaryMap<K, V, S> where
S: Unpin,
V: Unpin,
S: Unpin,
V: Unpin,
impl<K, V, S> Sync for SparseSecondaryMap<K, V, S> where
S: Sync,
V: Sync,
S: Sync,
V: Sync,
impl<K, V, S> UnwindSafe for SparseSecondaryMap<K, V, S> where
S: UnwindSafe,
V: UnwindSafe,
S: UnwindSafe,
V: UnwindSafe,
impl<K, V, S> RefUnwindSafe for SparseSecondaryMap<K, V, S> where
S: RefUnwindSafe,
V: RefUnwindSafe,
S: RefUnwindSafe,
V: RefUnwindSafe,
Blanket Implementations
impl<T> From<T> for T
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impl<T, U> Into<U> for T where
U: From<T>,
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U: From<T>,
impl<I> IntoIterator for I where
I: Iterator,
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I: Iterator,
type Item = <I as Iterator>::Item
The type of the elements being iterated over.
type IntoIter = I
Which kind of iterator are we turning this into?
fn into_iter(self) -> I
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impl<T> ToOwned for T where
T: Clone,
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T: Clone,
type Owned = T
The resulting type after obtaining ownership.
fn to_owned(&self) -> T
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fn clone_into(&self, target: &mut T)
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impl<T, U> TryFrom<U> for T where
U: Into<T>,
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U: Into<T>,
type Error = Infallible
The type returned in the event of a conversion error.
fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>
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impl<T, U> TryInto<U> for T where
U: TryFrom<T>,
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U: TryFrom<T>,
type Error = <U as TryFrom<T>>::Error
The type returned in the event of a conversion error.
fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>
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impl<T> Borrow<T> for T where
T: ?Sized,
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T: ?Sized,
impl<T> BorrowMut<T> for T where
T: ?Sized,
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T: ?Sized,
fn borrow_mut(&mut self) -> &mut T
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impl<T> Any for T where
T: 'static + ?Sized,
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T: 'static + ?Sized,