Struct idcontain::Id

pub struct Id<T> { /* fields omitted */ }

The Id of an element of type T as returned by IdSlab insertions.

Id-s are opaque, but Copy, comparable and hashable. Think of an Id as a safe *const T which you can dereference if you have a reference to the originating IdSlab.

Implementation

Internally an Id is implemented as an (index, tag) pair. The index points to a slot in the IdSlab, while the tag allows disambiguating between values when a slot gets reused (a matching tag is stored in the slot and is incremented every time a value is removed from that slot).

Methods

impl<T> Id<T>

pub fn invalid() -> Self

Returns an invalid Id (which will never be returned by a container).

Panics

None.

Example

let id_slab: IdSlab<&'static str> = IdSlab::new();
assert!(!id_slab.contains(Id::invalid()));

pub fn cast<U>(self) -> Id<U>

Casts the Id to an Id of a different type.

This is handy when using IdSlab to generate proxy Id-s for an IdMap.

Panics

None.

Example

let mut id_slab: IdSlab<()> = IdSlab::new();
let id: Id<u32> = id_slab.insert(()).cast();

Trait Implementations

impl<T> Debug for Id<T>

fn fmt(&self, formatter: &mut Formatter) -> FmtResult

Formats the value using the given formatter.

impl<T> Hash for Id<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,

Feeds a slice of this type into the given [Hasher].

impl<T> PartialOrd for Id<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

This method tests less than (for self and other) and is used by the < operator.

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

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

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

This method tests greater than (for self and other) and is used by the > operator.

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

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

impl<T> PartialEq for Id<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 !=.

impl<T> Ord for Id<T>

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

This method returns an Ordering between self and other.

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

Compares and returns the maximum of two values.

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

Compares and returns the minimum of two values.

impl<T> Clone for Id<T>

fn clone(&self) -> Self

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<T> Copy for Id<T>

impl<T> Eq for Id<T>

impl<T> Default for Id<T>

fn default() -> Self

Returns the "default value" for a type.

impl<T> Index<Id<T>> for IdSlab<T>

type Output = T

The returned type after indexing.

fn index(&self, id: Id<T>) -> &Self::Output

Performs the indexing (container[index]) operation.

impl<T> IndexMut<Id<T>> for IdSlab<T>

fn index_mut(&mut self, id: Id<T>) -> &mut Self::Output

Performs the mutable indexing (container[index]) operation.