Struct janetrs::allocator::Scratch

pub struct Scratch;

Memory allocator that will certainly be cleaned up in the next Janet Garbage Collection cycle.

If this crate are build with the nightly feature enabled, this type also implements the Allocator trait. That means that with the nightly feature set it’s possible to use this allocator with Rust types that uses allocator as parameter, like Box.

Implementations

impl Scratch

pub fn malloc(&self, layout: Layout) -> Option<NonNull<[u8]>>

Attempts to allocate a block of memory.

On success, returns a NonNull<[u8]> meeting the size and alignment guarantees of layout.

The returned block may have a larger size than specified by layout.size(), and may or may not have its contents initialized.

pub fn calloc(&self, layout: Layout) -> Option<NonNull<[u8]>>

Behaves like allocate, but also ensures that the returned memory is zero-initialized.

pub unsafe fn realloc( &self, ptr: NonNull<[u8]>, layout: Layout, new_size: usize ) -> Option<NonNull<[u8]>>

Shrink or grow a block of memory to the given new_size. The block is described by the given ptr pointer and layout.

Safety

This function is unsafe because undefined behavior can result if the caller does not ensure all of the following:

• ptr must be currently allocated via this allocator,
• layout must be the same layout that was used to allocate that block of memory,
• new_size must be greater than zero.
• new_size, when rounded up to the nearest multiple of layout.align(), must not overflow (i.e., the rounded value must be less than usize::MAX).

pub unsafe fn free(&self, ptr: NonNull<[u8]>)

Deallocates the memory referenced by ptr.

Safety

ptr must denote a block of memory currently allocated via this allocator.

Trait Implementations

impl Allocator for Scratch

Available on crate feature nightly only.

fn allocate(&self, layout: Layout) -> Result<NonNull<[u8]>, AllocError>

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

Attempts to allocate a block of memory.

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

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

Deallocates the memory referenced by ptr.

fn allocate_zeroed(&self, layout: Layout) -> Result<NonNull<[u8]>, AllocError>

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

Behaves like allocate, but also ensures that the returned memory is zero-initialized.

unsafe fn grow( &self, ptr: NonNull<u8>, old_layout: Layout, new_layout: Layout ) -> Result<NonNull<[u8]>, AllocError>

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

Attempts to extend the memory block.

unsafe fn grow_zeroed( &self, ptr: NonNull<u8>, old_layout: Layout, new_layout: Layout ) -> Result<NonNull<[u8]>, AllocError>

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

Behaves like grow, but also ensures that the new contents are set to zero before being returned.

unsafe fn shrink( &self, ptr: NonNull<u8>, old_layout: Layout, new_layout: Layout ) -> Result<NonNull<[u8]>, AllocError>

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

Attempts to shrink the memory block.

fn by_ref(&self) -> &Self

where Self: Sized,

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

Creates a “by reference” adapter for this instance of Allocator.

impl Clone for Scratch

fn clone(&self) -> Scratch

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for Scratch

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

Formats the value using the given formatter.

impl Default for Scratch

fn default() -> Scratch

Returns the “default value” for a type.

impl Copy for Scratch