Struct alloc_compose::NullAlloc

pub struct NullAlloc;

An emphatically empty implementation of AllocRef.

Although it has no direct use, it is useful as a "terminator" in composite allocators.

Examples

The NullAlloc will always return Err:

#![feature(allocator_api)]

use alloc_compose::NullAlloc;
use std::alloc::{AllocInit, AllocRef, Global, Layout};

let memory = NullAlloc.alloc(Layout::new::<u32>(), AllocInit::Uninitialized);
assert!(memory.is_err())

Even if a zero-sized allocation is requested:

#![feature(allocator_api)]

use alloc_compose::NullAlloc;
use std::alloc::{AllocInit, AllocRef, Global, Layout};

let memory = NullAlloc.alloc(Layout::new::<()>(), AllocInit::Uninitialized);
assert!(memory.is_err())

Trait Implementations

impl AllocRef for NullAlloc

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

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

Will always return Err(AllocErr).

unsafe fn dealloc(&mut self, _ptr: NonNull<u8>, _layout: Layout)

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

Must not be called, as alloc always fails.

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)

Must not be called, as alloc always fails.

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)

Must not be called, as alloc always fails.

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 Clone for NullAlloc

fn clone(&self) -> NullAlloc

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for NullAlloc

impl Debug for NullAlloc

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

Formats the value using the given formatter.

impl Owns for NullAlloc

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

Will always return `false.