Struct Key 

pub struct Key<T> { /* private fields */ }

A handle into an Arena<T>.

Phantom-typed, so a Key<Face> cannot be used to index an Arena<Edge>. The marker is fn() -> T so the key stays Copy, Send and Sync regardless of T.

Implementations

impl<T> Key<T>

pub const fn scope(self) -> u32

Which arena issued this key.

UNSCOPED for a key that has not been bound to one.

pub const fn with_scope(self, scope: u32) -> Self

This key, bound to the arena with the given identifier.

For a deserializer, which rebuilds handles before it has an arena to bind them to. Nothing else should need it: a key that came from an arena already names the right one, and moving a key between arenas is the mistake the scope exists to catch.

pub const fn index(self) -> u32

Position of the slot this key refers to.

pub const fn generation(self) -> u32

Generation stamp, used to detect a key outliving its slot.

pub const fn from_parts(index: u32, generation: u32) -> Self

A key naming a given slot, for reading a document back from a file.

Deliberately narrow. Forging a handle is precisely what generations exist to prevent, and Arena::insert is what issues one within a process. But a file records the handles a document was written with, and a reader that could not rebuild them would have to renumber everything, which is to say, hand back a different document.

A key made this way is not trusted: it resolves through Arena::get like any other, so a stale or out-of-range one comes back None rather than aliasing whatever sits at that index.

Trait Implementations

impl<T> Clone for Key<T>

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<T> Copy for Key<T>

impl<T> Debug for Key<T>

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

Formats the value using the given formatter.

impl<T> Eq for Key<T>

impl<T> Hash for Key<T>

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<T> Index<Key<T>> for Arena<T>

fn index(&self, key: Key<T>) -> &T

Panics

If the key is stale. Use Arena::get where that is a possibility.

type Output = T

The returned type after indexing.

impl<T> IndexMut<Key<T>> for Arena<T>

fn index_mut(&mut self, key: Key<T>) -> &mut T

Panics

If the key is stale. Use Arena::get_mut where that is a possibility.

impl<T> Ord for Key<T>

fn cmp(&self, other: &Self) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

where Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized,

Restrict a value to a certain interval.

impl<T> PartialEq for Key<T>

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

Tests for self and other values to be equal, and is used by ==.

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

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

impl<T> PartialOrd for Key<T>

fn partial_cmp(&self, other: &Self) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

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

Tests less than (for self and other) and is used by the < operator.

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

Tests less than or equal to (for self and other) and is used by the <= operator.

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

Tests greater than (for self and other) and is used by the > operator.

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

Tests greater than or equal to (for self and other) and is used by the >= operator.