Struct BumpAlloc

pub struct BumpAlloc<T> { /* private fields */ }

A bump allocator for type T.

Example

use rust_dsa::BumpAlloc;

// First, we create a new bump allocator.
let mut arena: BumpAlloc<i32> = BumpAlloc::new(3);

// We can allocate pointers.
let ptr1 = arena.alloc().unwrap();
let ptr2 = arena.alloc().unwrap();
let ptr3 = arena.alloc().unwrap();

// Eventually, we run out of room.
assert_eq!(arena.alloc(), None);
assert_eq!(arena.available_slots(), 0);

// We can free allocations to make more room.
arena.free(ptr1);
arena.free(ptr2);
arena.free(ptr3);
assert!(arena.can_alloc());
assert!(arena.alloc().is_some());
assert!(arena.alloc().is_some());

// We can iterate over existing allocations.
assert_eq!(arena.allocations().count(), 2);

// Finally, we can free everything.
arena.free_all();

Implementations

impl<T> BumpAlloc<T>

pub fn new(n: usize) -> BumpAlloc<T>

Creates a new allocator.

Panics

Panics if the allocation fails or if size_of::<T>() is zero.

pub fn alloc(&mut self) -> Option<NonNull<T>>

Allocates a slot, if one is available.

Example

use rust_dsa::BumpAlloc;

let mut arena: BumpAlloc<char> = BumpAlloc::new(3);

assert!(arena.alloc().is_some());
assert!(arena.alloc().is_some());
assert!(arena.alloc().is_some());
assert!(arena.alloc().is_none());

pub fn free(&mut self, ptr: NonNull<T>)

Frees a slot.

Panics

Panics if the pointer was not allocated by this BumpAlloc struct.

Example

use rust_dsa::BumpAlloc;

let mut arena: BumpAlloc<String> = BumpAlloc::new(10);

let ptr = arena.alloc().unwrap();
assert_eq!(arena.available_slots(), 9);

arena.free(ptr);

assert_eq!(arena.available_slots(), 10);

pub fn allocations(&self) -> Allocations<'_, T>

Returns an interator over the currently allocated pointers.

Example

use rust_dsa::BumpAlloc;

let mut arena: BumpAlloc<u8> = BumpAlloc::new(100);
arena.alloc();
arena.alloc();
arena.alloc();
assert_eq!(arena.available_slots(), 97);

let allocations: Vec<_> = arena.allocations().collect();
for ptr in allocations {
    arena.free(ptr);
}

assert_eq!(arena.available_slots(), 100);

pub fn free_all(&mut self)

Frees all the currently allocated pointers.

Example

use rust_dsa::BumpAlloc;

let mut arena: BumpAlloc<i32> = BumpAlloc::new(10);
arena.alloc();
arena.alloc();
arena.alloc();
assert_eq!(arena.available_slots(), 7);

arena.free_all();

assert_eq!(arena.available_slots(), 10);

pub fn available_slots(&self) -> usize

Returns the number of available slots that can be allocated.

Example

use rust_dsa::BumpAlloc;

let mut arena: BumpAlloc<i32> = BumpAlloc::new(10);
assert_eq!(arena.available_slots(), 10);

arena.alloc();
arena.alloc();
arena.alloc();
assert_eq!(arena.available_slots(), 7);

pub fn can_alloc(&self) -> bool

Returns true if BumpAlloc::alloc will return Some.

Example

use rust_dsa::BumpAlloc;

let mut arena: BumpAlloc<bool> = BumpAlloc::new(1);
assert!(arena.can_alloc());

arena.alloc();

assert!(!arena.can_alloc());

Trait Implementations

impl<T> Drop for BumpAlloc<T>

fn drop(&mut self)

Executes the destructor for this type.