Struct vec_arena::Arena [−][src]
pub struct Arena<T> { /* fields omitted */ }
This crate is now deprecated in favor of slab.
An object arena.
Arena<T>
holds an array of slots for storing objects.
Every slot is always in one of two states: occupied or vacant.
Essentially, this is equivalent to Vec<Option<T>>
.
Insert and remove
When inserting a new object into arena, a vacant slot is found and then the object is placed
into the slot. If there are no vacant slots, the array is reallocated with bigger capacity.
The cost of insertion is amortized O(1)
.
When removing an object, the slot containing it is marked as vacant and the object is returned.
The cost of removal is O(1)
.
use vec_arena::Arena; let mut arena = Arena::new(); let a = arena.insert(10); let b = arena.insert(20); assert_eq!(a, 0); // 10 was placed at index 0 assert_eq!(b, 1); // 20 was placed at index 1 assert_eq!(arena.remove(a), Some(10)); assert_eq!(arena.get(a), None); // slot at index 0 is now vacant assert_eq!(arena.insert(30), 0); // slot at index 0 is reused
Indexing
You can also access objects in an arena by index, just like you would in a Vec
.
However, accessing a vacant slot by index or using an out-of-bounds index will result in panic.
use vec_arena::Arena; let mut arena = Arena::new(); let a = arena.insert(10); let b = arena.insert(20); assert_eq!(arena[a], 10); assert_eq!(arena[b], 20); arena[a] += arena[b]; assert_eq!(arena[a], 30);
To access slots without fear of panicking, use get()
and
get_mut()
, which return Option
s.
Implementations
impl<T> Arena<T>
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impl<T> Arena<T>
[src]pub fn new() -> Self
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👎 Deprecated since 1.2.0: This crate is now deprecated in favor of slab.
pub fn new() -> Self
[src]This crate is now deprecated in favor of slab.
Constructs a new, empty arena.
The arena will not allocate until objects are inserted into it.
Examples
use vec_arena::Arena; let mut arena: Arena<i32> = Arena::new();
pub fn with_capacity(cap: usize) -> Self
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👎 Deprecated since 1.2.0: This crate is now deprecated in favor of slab.
pub fn with_capacity(cap: usize) -> Self
[src]This crate is now deprecated in favor of slab.
Constructs a new, empty arena with the specified capacity (number of slots).
The arena will be able to hold exactly cap
objects without reallocating.
If cap
is 0, the arena will not allocate.
Examples
use vec_arena::Arena; let mut arena = Arena::with_capacity(10); assert_eq!(arena.len(), 0); assert_eq!(arena.capacity(), 10); // These inserts are done without reallocating... for i in 0..10 { arena.insert(i); } assert_eq!(arena.capacity(), 10); // ... but this one will reallocate. arena.insert(11); assert!(arena.capacity() > 10);
pub fn capacity(&self) -> usize
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👎 Deprecated since 1.2.0: This crate is now deprecated in favor of slab.
pub fn capacity(&self) -> usize
[src]This crate is now deprecated in favor of slab.
Returns the number of slots in the arena.
Examples
use vec_arena::Arena; let arena: Arena<i32> = Arena::with_capacity(10); assert_eq!(arena.capacity(), 10);
pub fn len(&self) -> usize
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👎 Deprecated since 1.2.0: This crate is now deprecated in favor of slab.
pub fn len(&self) -> usize
[src]This crate is now deprecated in favor of slab.
Returns the number of occupied slots in the arena.
Examples
use vec_arena::Arena; let mut arena = Arena::new(); assert_eq!(arena.len(), 0); for i in 0..10 { arena.insert(()); assert_eq!(arena.len(), i + 1); }
pub fn is_empty(&self) -> bool
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👎 Deprecated since 1.2.0: This crate is now deprecated in favor of slab.
pub fn is_empty(&self) -> bool
[src]This crate is now deprecated in favor of slab.
Returns true
if all slots are vacant.
Examples
use vec_arena::Arena; let mut arena = Arena::new(); assert!(arena.is_empty()); arena.insert(1); assert!(!arena.is_empty());
pub fn next_vacant(&self) -> usize
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👎 Deprecated since 1.2.0: This crate is now deprecated in favor of slab.
pub fn next_vacant(&self) -> usize
[src]This crate is now deprecated in favor of slab.
Returns the index of the slot that next insert
will use if no
mutating calls take place in between.
Examples
use vec_arena::Arena; let mut arena = Arena::new(); let a = arena.next_vacant(); let b = arena.insert(1); assert_eq!(a, b); let c = arena.next_vacant(); let d = arena.insert(2); assert_eq!(c, d);
pub fn insert(&mut self, object: T) -> usize
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👎 Deprecated since 1.2.0: This crate is now deprecated in favor of slab.
pub fn insert(&mut self, object: T) -> usize
[src]This crate is now deprecated in favor of slab.
Inserts an object into the arena and returns the slot index it was stored in.
The arena will reallocate if it’s full.
Examples
use vec_arena::Arena; let mut arena = Arena::new(); let a = arena.insert(1); let b = arena.insert(2); assert!(a != b);
pub fn remove(&mut self, index: usize) -> Option<T>
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👎 Deprecated since 1.2.0: This crate is now deprecated in favor of slab.
pub fn remove(&mut self, index: usize) -> Option<T>
[src]This crate is now deprecated in favor of slab.
Removes the object stored at index
from the arena and returns it.
If the slot is vacant or index
is out of bounds, None
will be returned.
Examples
use vec_arena::Arena; let mut arena = Arena::new(); let a = arena.insert("hello"); assert_eq!(arena.len(), 1); assert_eq!(arena.remove(a), Some("hello")); assert_eq!(arena.len(), 0); assert_eq!(arena.remove(a), None);
pub fn retain<F>(&mut self, f: F) where
F: FnMut(usize, &mut T) -> bool,
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👎 Deprecated since 1.2.0: This crate is now deprecated in favor of slab.
pub fn retain<F>(&mut self, f: F) where
F: FnMut(usize, &mut T) -> bool,
[src]This crate is now deprecated in favor of slab.
Retains objects for which the closure returns true
.
All other objects will be removed from the arena.
Examples
use vec_arena::Arena; let mut arena = Arena::new(); let a = arena.insert(0); let b = arena.insert(1); let c = arena.insert(2); arena.retain(|k, v| k == a || *v == 1); assert!(arena.get(a).is_some()); assert!(arena.get(b).is_some()); assert!(arena.get(c).is_none());
pub fn clear(&mut self)
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👎 Deprecated since 1.2.0: This crate is now deprecated in favor of slab.
pub fn clear(&mut self)
[src]This crate is now deprecated in favor of slab.
Clears the arena, removing and dropping all objects it holds.
Keeps the allocated memory for reuse.
Examples
use vec_arena::Arena; let mut arena = Arena::new(); for i in 0..10 { arena.insert(i); } assert_eq!(arena.len(), 10); arena.clear(); assert_eq!(arena.len(), 0);
pub fn get(&self, index: usize) -> Option<&T>
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👎 Deprecated since 1.2.0: This crate is now deprecated in favor of slab.
pub fn get(&self, index: usize) -> Option<&T>
[src]This crate is now deprecated in favor of slab.
Returns a reference to the object stored at index
.
If the slot is vacant or index
is out of bounds, None
will be returned.
Examples
use vec_arena::Arena; let mut arena = Arena::new(); let index = arena.insert("hello"); assert_eq!(arena.get(index), Some(&"hello")); arena.remove(index); assert_eq!(arena.get(index), None);
pub fn get_mut(&mut self, index: usize) -> Option<&mut T>
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👎 Deprecated since 1.2.0: This crate is now deprecated in favor of slab.
pub fn get_mut(&mut self, index: usize) -> Option<&mut T>
[src]This crate is now deprecated in favor of slab.
Returns a mutable reference to the object stored at index
.
If the slot is vacant or index
is out of bounds, None
will be returned.
Examples
use vec_arena::Arena; let mut arena = Arena::new(); let index = arena.insert(7); assert_eq!(arena.get_mut(index), Some(&mut 7)); *arena.get_mut(index).unwrap() *= 10; assert_eq!(arena.get_mut(index), Some(&mut 70));
pub fn swap(&mut self, a: usize, b: usize)
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👎 Deprecated since 1.2.0: This crate is now deprecated in favor of slab.
pub fn swap(&mut self, a: usize, b: usize)
[src]This crate is now deprecated in favor of slab.
Swaps two objects in the arena.
The two indices are a
and b
.
Panics
Panics if any of the indices is out of bounds or any of the slots is vacant.
Examples
use vec_arena::Arena; let mut arena = Arena::new(); let a = arena.insert(7); let b = arena.insert(8); arena.swap(a, b); assert_eq!(arena.get(a), Some(&8)); assert_eq!(arena.get(b), Some(&7));
pub fn reserve(&mut self, additional: usize)
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👎 Deprecated since 1.2.0: This crate is now deprecated in favor of slab.
pub fn reserve(&mut self, additional: usize)
[src]This crate is now deprecated in favor of slab.
Reserves capacity for at least additional
more objects to be inserted.
The arena may reserve more space to avoid frequent reallocations.
Panics
Panics if the new capacity overflows usize
.
Examples
use vec_arena::Arena; let mut arena = Arena::new(); arena.insert("hello"); arena.reserve(10); assert!(arena.capacity() >= 11);
pub fn reserve_exact(&mut self, additional: usize)
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👎 Deprecated since 1.2.0: This crate is now deprecated in favor of slab.
pub fn reserve_exact(&mut self, additional: usize)
[src]This crate is now deprecated in favor of slab.
Reserves the minimum capacity for exactly additional
more objects to be inserted.
Note that the allocator may give the arena more space than it requests.
Panics
Panics if the new capacity overflows usize
.
Examples
use vec_arena::Arena; let mut arena = Arena::new(); arena.insert("hello"); arena.reserve_exact(10); assert!(arena.capacity() >= 11);
pub fn iter(&self) -> Iter<'_, T>ⓘ
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👎 Deprecated since 1.2.0: This crate is now deprecated in favor of slab.
pub fn iter(&self) -> Iter<'_, T>ⓘ
[src]This crate is now deprecated in favor of slab.
Returns an iterator over occupied slots.
Examples
use vec_arena::Arena; let mut arena = Arena::new(); arena.insert(1); arena.insert(2); arena.insert(4); let mut iterator = arena.iter(); assert_eq!(iterator.next(), Some((0, &1))); assert_eq!(iterator.next(), Some((1, &2))); assert_eq!(iterator.next(), Some((2, &4)));
pub fn iter_mut(&mut self) -> IterMut<'_, T>ⓘ
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👎 Deprecated since 1.2.0: This crate is now deprecated in favor of slab.
pub fn iter_mut(&mut self) -> IterMut<'_, T>ⓘ
[src]This crate is now deprecated in favor of slab.
Returns an iterator that returns mutable references to objects.
Examples
use vec_arena::Arena; let mut arena = Arena::new(); arena.insert("zero".to_string()); arena.insert("one".to_string()); arena.insert("two".to_string()); for (index, object) in arena.iter_mut() { *object = index.to_string() + " " + object; } let mut iterator = arena.iter(); assert_eq!(iterator.next(), Some((0, &"0 zero".to_string()))); assert_eq!(iterator.next(), Some((1, &"1 one".to_string()))); assert_eq!(iterator.next(), Some((2, &"2 two".to_string())));
pub fn shrink_to_fit(&mut self)
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👎 Deprecated since 1.2.0: This crate is now deprecated in favor of slab.
pub fn shrink_to_fit(&mut self)
[src]This crate is now deprecated in favor of slab.
Shrinks the capacity of the arena as much as possible.
It will drop down as close as possible to the length but the allocator may still inform the arena that there is space for a few more elements.
Examples
use vec_arena::Arena; let mut arena = Arena::with_capacity(10); arena.insert("first".to_string()); arena.insert("second".to_string()); arena.insert("third".to_string()); assert_eq!(arena.capacity(), 10); arena.shrink_to_fit(); assert!(arena.capacity() >= 3);
Trait Implementations
impl<T> FromIterator<T> for Arena<T>
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impl<T> FromIterator<T> for Arena<T>
[src]fn from_iter<U: IntoIterator<Item = T>>(iter: U) -> Arena<T>
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fn from_iter<U: IntoIterator<Item = T>>(iter: U) -> Arena<T>
[src]Creates a value from an iterator. Read more
impl<T> IntoIterator for Arena<T>
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impl<T> IntoIterator for Arena<T>
[src]impl<'a, T> IntoIterator for &'a Arena<T>
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impl<'a, T> IntoIterator for &'a Arena<T>
[src]Auto Trait Implementations
impl<T> Send for Arena<T> where
T: Send,
T: Send,
impl<T> Sync for Arena<T> where
T: Sync,
T: Sync,
impl<T> Unpin for Arena<T> where
T: Unpin,
T: Unpin,
Blanket Implementations
impl<T> BorrowMut<T> for T where
T: ?Sized,
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impl<T> BorrowMut<T> for T where
T: ?Sized,
[src]pub fn borrow_mut(&mut self) -> &mut T
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pub fn borrow_mut(&mut self) -> &mut T
[src]Mutably borrows from an owned value. Read more
impl<T> ToOwned for T where
T: Clone,
[src]
impl<T> ToOwned for T where
T: Clone,
[src]type Owned = T
type Owned = T
The resulting type after obtaining ownership.
pub fn to_owned(&self) -> T
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pub fn to_owned(&self) -> T
[src]Creates owned data from borrowed data, usually by cloning. Read more
pub fn clone_into(&self, target: &mut T)
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pub fn clone_into(&self, target: &mut T)
[src]🔬 This is a nightly-only experimental API. (toowned_clone_into
)
recently added
Uses borrowed data to replace owned data, usually by cloning. Read more