Struct Arena

pub(crate) struct Arena {
    start: Cell<*mut MaybeUninit<u8>>,
    end: Cell<*mut MaybeUninit<u8>>,
    chunks: RefCell<Vec<Box<[MaybeUninit<u8>]>>>,
}

🔬This is a nightly-only experimental API. (proc_macro_internals #27812)

A minimal arena allocator inspired by rustc_arena::DroplessArena.

This is unfortunately a complete re-implementation rather than a dependency as it is difficult to depend on crates from within proc_macro, due to it being built at the same time as std.

This arena doesn’t have support for allocating anything other than byte slices, as that is all that is necessary.

Fields

start: Cell<*mut MaybeUninit<u8>>

🔬This is a nightly-only experimental API. (proc_macro_internals #27812)

end: Cell<*mut MaybeUninit<u8>>

🔬This is a nightly-only experimental API. (proc_macro_internals #27812)

chunks: RefCell<Vec<Box<[MaybeUninit<u8>]>>>

🔬This is a nightly-only experimental API. (proc_macro_internals #27812)

Implementations

impl Arena

pub(crate) fn new() -> Self

🔬This is a nightly-only experimental API. (proc_macro_internals #27812)

fn grow(&self, additional: usize)

🔬This is a nightly-only experimental API. (proc_macro_internals #27812)

Add a new chunk with at least additional free bytes.

fn alloc_raw_without_grow(&self, bytes: usize) -> Option<&mut [MaybeUninit<u8>]>

🔬This is a nightly-only experimental API. (proc_macro_internals #27812)

Allocates a byte slice with specified size from the current memory chunk. Returns None if there is no free space left to satisfy the request.

fn alloc_raw(&self, bytes: usize) -> &mut [MaybeUninit<u8>]

🔬This is a nightly-only experimental API. (proc_macro_internals #27812)

pub(crate) fn alloc_str<'a>(&'a self, string: &str) -> &'a mut str

🔬This is a nightly-only experimental API. (proc_macro_internals #27812)