Struct alloc_compose::Region

pub struct Region<'a> { /* fields omitted */ }

Allocator over an user-defined region of memory.

Examples

#![feature(allocator_api)]

use alloc_compose::{Owns, Region};
use core::alloc::{AllocInit, AllocRef, Layout};

let mut data = [0; 64];
let mut region = Region::new(&mut data);

let memory = region.alloc(Layout::new::<u32>(), AllocInit::Uninitialized)?;
assert!(region.owns(memory));

It's possible to deallocate the latest memory block allocated:

unsafe { region.dealloc(memory.ptr, Layout::new::<u32>()) };
assert!(!region.owns(memory));

Methods

impl<'a> Region<'a>

pub fn new(data: &'a mut [u8]) -> Self

pub const fn capacity(&self) -> usize

Returns the total capacity available in this allocator.

pub fn capacity_left(&self) -> usize

Returns the free capacity left for allocating.

pub fn reset(&mut self)

Resets the allocator.

This implies, that capacity() and capacity_left() are equal afterwards.

pub fn is_last_block(&self, memory: MemoryBlock) -> bool

Checks if memory is the latest block, which was allocated. For those blocks, it's possible to deallocate them or to grow or shrink them in place.

Trait Implementations

impl<'_> AllocRef for Region<'_>

fn alloc(
    &mut self,
    layout: Layout,
    init: AllocInit
) -> Result<MemoryBlock, AllocErr>

🔬 This is a nightly-only experimental API. (allocator_api)

Attempts to allocate a block of memory.

unsafe fn dealloc(&mut self, ptr: NonNull<u8>, layout: Layout)

🔬 This is a nightly-only experimental API. (allocator_api)

Deallocates the memory referenced by ptr.

unsafe fn grow(
    &mut self,
    ptr: NonNull<u8>,
    layout: Layout,
    new_size: usize,
    placement: ReallocPlacement,
    init: AllocInit
) -> Result<MemoryBlock, AllocErr>

🔬 This is a nightly-only experimental API. (allocator_api)

Attempts to extend the memory block.

unsafe fn shrink(
    &mut self,
    ptr: NonNull<u8>,
    layout: Layout,
    new_size: usize,
    placement: ReallocPlacement
) -> Result<MemoryBlock, AllocErr>

🔬 This is a nightly-only experimental API. (allocator_api)

Attempts to shrink the memory block.

fn by_ref(&mut self) -> &mut Self

🔬 This is a nightly-only experimental API. (allocator_api)

Creates a "by reference" adaptor for this instance of AllocRef.

impl<'_> Debug for Region<'_>

fn fmt(&self, f: &mut Formatter) -> Result

Formats the value using the given formatter.

impl<'_> Owns for Region<'_>

fn owns(&self, memory: MemoryBlock) -> bool

Returns if the allocator owns the passed MemoryBlock.