TypedArena in rustc_arena - Rust
Description: An arena that can hold objects of only one type.

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## TypedArena

# Struct TypedArena

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    pub struct TypedArena<T> {
        pub(crate) ptr: Cell<*mut T>,
        pub(crate) end: Cell<*mut T>,
        pub(crate) chunks: RefCell<Vec<ArenaChunk<T>>>,
        pub(crate) _own: PhantomData<T>,
    }

Expand description

An arena that can hold objects of only one type.

## Fields§

§`ptr: Cell<*mut T>`

A pointer to the next object to be allocated.

§`end: Cell<*mut T>`

A pointer to the end of the allocated area. When this pointer is reached, a new chunk is allocated.

§`chunks: RefCell<Vec<ArenaChunk<T>>>`

A vector of arena chunks.

§`_own: PhantomData<T>`

Marker indicating that dropping the arena causes its owned instances of `T` to be dropped.

## Implementations§

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### impl<T> TypedArena<T>

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#### pub fn alloc(&self, object: T) -> &mut T

Allocates an object in the `TypedArena`, returning a reference to it.

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#### pub(crate) fn can_allocate(&self, additional: usize) -> bool

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#### pub(crate) unsafe fn alloc_raw_slice(&self, len: usize) -> *mut T

Allocates storage for `len >= 1` values in this arena, and returns a raw pointer to the first value’s storage.

##### §Safety

Caller must initialize each of the `len` slots to a droppable value before the arena is dropped.

In practice, this typically means that the caller must be able to raw-copy `len` already-initialized values into the slice without any possibility of panicking.

FIXME(Zalathar): This is very fragile; perhaps we need a different approach to arena-allocating slices of droppable values.

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#### pub fn alloc_from_iter<I: IntoIterator<Item = T>>(&self, iter: I) -> &mut [T]

Allocates the elements of this iterator into a contiguous slice in the `TypedArena`.

Note: for reasons of reentrancy and panic safety we collect into a `SmallVec<[_; 8]>` before storing the elements in the arena.

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#### pub fn try_alloc_from_iter<E>( &self, iter: impl IntoIterator<Item = Result<T, E>>, ) -> Result<&mut [T], E>

Allocates the elements of this iterator into a contiguous slice in the `TypedArena`.

Note: for reasons of reentrancy and panic safety we collect into a `SmallVec<[_; 8]>` before storing the elements in the arena.

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#### pub(crate) fn grow(&self, additional: usize)

Grows the arena.

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#### pub(crate) fn clear_last_chunk(&self, last_chunk: &mut ArenaChunk<T>)

## Trait Implementations§

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### impl<T> Default for TypedArena<T>

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#### fn default() -> TypedArena<T>

Creates a new `TypedArena`.

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### impl<T> Drop for TypedArena<T>

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#### fn drop(&mut self)

Executes the destructor for this type. Read more
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### impl<T: Send> Send for TypedArena<T>

## Auto Trait Implementations§

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### impl<T> !Freeze for TypedArena<T>

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### impl<T> !RefUnwindSafe for TypedArena<T>

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### impl<T> !Sync for TypedArena<T>

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### impl<T> Unpin for TypedArena<T>
where T: Unpin,

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### impl<T> UnsafeUnpin for TypedArena<T>

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### impl<T> UnwindSafe for TypedArena<T>
where T: UnwindSafe + RefUnwindSafe,

## Blanket Implementations§

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### impl<T> Any for T
where T: 'static + ?Sized,

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#### fn type_id(&self) -> TypeId

Gets the `TypeId` of `self`. Read more
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### impl<T> Borrow<T> for T
where T: ?Sized,

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#### fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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### impl<T> BorrowMut<T> for T
where T: ?Sized,

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#### fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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### impl<T> From<T> for T

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#### fn from(t: T) -> T

Returns the argument unchanged.

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### impl<T, U> Into<U> for T
where U: From<T>,

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#### fn into(self) -> U

Calls `U::from(self)`.

That is, this conversion is whatever the implementation of `From<T> for U` chooses to do.

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### impl<T, U> TryFrom<U> for T
where U: Into<T>,

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#### type Error = Infallible

The type returned in the event of a conversion error.
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#### fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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### impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

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#### type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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#### fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.

## Layout§

Note: Most layout information is completely unstable and may even differ between compilations. The only exception is types with certain `repr(...)` attributes. Please see the Rust Reference's “Type Layout” chapter for details on type layout guarantees.

Size: 48 bytes