Struct Arena 

pub struct Arena<T, Options: ArenaOptions<T> = Options>(/* private fields */);

An arena that allocates items of type T in non-amortized O(1) (constant) time.

The arena allocates fixed-size chunks of memory, each able to hold up to Options::ChunkSize items. All items are allocated on the heap.

Panics

The arena may panic when created or used if mem::size_of::<T>() times Options::ChunkSize is greater than usize::MAX.

Implementations

impl<T, Options: ArenaOptions<T>> Arena<T, Options>

pub fn new() -> Self

Creates a new Arena.

pub fn len(&self) -> usize

Returns the total number of items that have been allocated.

pub fn is_empty(&self) -> bool

Checks whether the arena is empty.

pub fn alloc(&self, value: T) -> &mut T

where Options: ArenaOptions<T, Mutable = Bool<true>>,

Allocates a new item in the arena and initializes it with value. Returns a reference to the allocated item.

This method calls handle_alloc_error if memory allocation fails; for a version that returns None instead, see Self::try_alloc.

pub fn try_alloc(&self, value: T) -> Option<&mut T>

where Options: ArenaOptions<T, Mutable = Bool<true>>,

Like Self::alloc, but returns None if memory allocation fails.

pub fn alloc_shared(&self, value: T) -> &T

Allocates a new item in the arena and initializes it with value. Returns a shared/immutable reference to the allocated item.

This method calls handle_alloc_error if memory allocation fails; for a version that returns None instead, see Self::try_alloc.

pub fn try_alloc_shared(&self, value: T) -> Option<&T>

Like Self::alloc_shared, but returns None if memory allocation fails.

pub fn iter(&self) -> Iter<'_, T, Options>

where Options: ArenaOptions<T, Mutable = Bool<false>>,

Returns an iterator over the items in this arena.

pub unsafe fn iter_unchecked(&self) -> Iter<'_, T, Options>

Returns an iterator over the items in this arena.

Safety

There must be no mutable references (or references derived from mutable references) to items (or parts of items) in this arena or instances of IterMut for this arena.

pub fn iter_mut(&mut self) -> IterMut<'_, T, Options>

Returns a mutable iterator over the items in this arena.

impl<T, Options> Arena<T, Options>

where Options: ArenaOptions<T, SupportsPositions = Bool<true>>,

pub fn iter_at(&self, position: &Position) -> Iter<'_, T, Options>

where Options: ArenaOptions<T, Mutable = Bool<false>>,

Returns an iterator starting at the specified position.

Panics

May panic if position does not refer to a position in this arena.

pub unsafe fn iter_at_unchecked( &self, position: &Position, ) -> Iter<'_, T, Options>

Returns an iterator starting at the specified position.

Panics

May panic if position does not refer to a position in this arena.

Safety

Same requirements as Self::iter_unchecked.

pub fn iter_mut_at(&mut self, position: &Position) -> IterMut<'_, T, Options>

Returns a mutable iterator starting at the specified position.

Panics

May panic if position does not refer to a position in this arena.

Trait Implementations

impl<T, Options: ArenaOptions<T>> Default for Arena<T, Options>

fn default() -> Self

Returns the “default value” for a type.

impl<T, Options> Drop for Arena<T, Options>

where Options: ArenaOptions<T>,

fn drop(&mut self)

Executes the destructor for this type.

impl<'a, T, Options> IntoIterator for &'a Arena<T, Options>

where Options: ArenaOptions<T, Mutable = Bool<false>>,

type IntoIter = Iter<'a, T, Options>

Which kind of iterator are we turning this into?

type Item = &'a T

The type of the elements being iterated over.

fn into_iter(self) -> Self::IntoIter

Creates an iterator from a value.

impl<'a, T, Options> IntoIterator for &'a mut Arena<T, Options>

where Options: ArenaOptions<T>,

type IntoIter = IterMut<'a, T, Options>

Which kind of iterator are we turning this into?

type Item = &'a mut T

The type of the elements being iterated over.

fn into_iter(self) -> Self::IntoIter

Creates an iterator from a value.

impl<T, Options: ArenaOptions<T>> IntoIterator for Arena<T, Options>

type IntoIter = IntoIter<T, Options>

Which kind of iterator are we turning this into?

type Item = T

The type of the elements being iterated over.

fn into_iter(self) -> Self::IntoIter

Creates an iterator from a value.

impl<T, Options> Send for Arena<T, Options>

where T: Send, Options: ArenaOptions<T>,