Struct internment::ArenaIntern

pub struct ArenaIntern<'a, T: ?Sized> { /* private fields */ }

An interned object reference with the data stored in an Arena<T>.

Implementations

impl<'a, T: ?Sized> ArenaIntern<'a, T>

pub fn into_ref(self) -> &'a T

Get a reference to a value interned into an arena.

This function allows you to store values into a structure inline, without having to take a &'a reference to an ArenaIntern<'a, T>. This is required as using std::ops::Deref or std::convert::AsRef requires a &self receiver, but doing so, due to the bounds of these traits’ functions, would implicitly require that this reference lives for 'a.

Example

Consider the following structures.

struct Bar {
    baz: String,
}

struct Foo<'a>(ArenaIntern<'a, Bar>);

The following code does not compile.

impl<'a> Foo<'a> {
    pub fn get_baz(self) -> &'a str {
        &self.0.as_ref().baz
        // ^^^ ERROR: cannot return value referencing local data `self.0`
    }
}

This similar code, which uses into_ref, does compile.

impl<'a> Foo<'a> {
    pub fn get_baz(self) -> &'a str {
        &self.0.into_ref().baz
    }
}

Trait Implementations

impl<'a, T: ?Sized> AsRef<T> for ArenaIntern<'a, T>

fn as_ref(&self) -> &T

Converts this type into a shared reference of the (usually inferred) input type.

impl<'a, T: ?Sized> Clone for ArenaIntern<'a, T>

fn clone(&self) -> Self

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<'a, T: Debug + ?Sized> Debug for ArenaIntern<'a, T>

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

Formats the value using the given formatter.

impl<'a, T: ?Sized + DeepSizeOf> DeepSizeOf for ArenaIntern<'a, T>

fn deep_size_of_children(&self, _context: &mut Context) -> usize

Returns an estimation of the heap-managed storage of this object. This does not include the size of the object itself.

fn deep_size_of(&self) -> usize

Returns an estimation of a total size of memory owned by the object, including heap-managed storage.

impl<'a, T: ?Sized> Deref for ArenaIntern<'a, T>

type Target = T

The resulting type after dereferencing.

fn deref(&self) -> &Self::Target

Dereferences the value.

impl<'a, T: Display + ?Sized> Display for ArenaIntern<'a, T>

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

Formats the value using the given formatter.

impl<'a, T: ?Sized> Hash for ArenaIntern<'a, T>

The hash implementation returns the hash of the pointer value, not the hash of the value pointed to. This should be irrelevant, since there is a unique pointer for every value, but it is observable, since you could compare the hash of the pointer with hash of the data itself.

fn hash<H: Hasher>(&self, state: &mut H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl<'a, T: ?Sized> PartialEq for ArenaIntern<'a, T>

fn eq(&self, other: &Self) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<'a, T: ?Sized> Copy for ArenaIntern<'a, T>

impl<'a, T: ?Sized> Eq for ArenaIntern<'a, T>